Scanning tunneling microscope (STM) is used to investigate the optical disc.The areas with and without data stampers are all observed carefully. Three-dimensional images of the disc surface clearly demonstrate the per...Scanning tunneling microscope (STM) is used to investigate the optical disc.The areas with and without data stampers are all observed carefully. Three-dimensional images of the disc surface clearly demonstrate the period, depth of the grooves and the shape of data stampers. Some phenomena of STM imaging are also discussed.展开更多
AIM:To evaluate the therapeutic effects of ranibizumab on optic disc and macular microvascular perfusion in central retinal vein occlusion(CRVO)with macular edema(ME).METHODS:Optical coherence tomography angiology(OCT...AIM:To evaluate the therapeutic effects of ranibizumab on optic disc and macular microvascular perfusion in central retinal vein occlusion(CRVO)with macular edema(ME).METHODS:Optical coherence tomography angiology(OCTA)parameters,including optic disc vessel density(VD;including whole-disc VD,intra-disc VD,and peripapillary VD),superficial/deep capillary plexus(SCP/DCP)VD,and central macular thickness(CMT)were analyzed.Additional assessments included best-corrected visual acuity(BCVA)via Early Treatment Diabetic Retinopathy Study(ETDRS)chart and hemorheological profiling.CRVO patients received monthly intravitreal ranibizumab injections for three consecutive months.Pre-and post-treatment parameters were statistically compared.RESULTS:The study comprised 60 CRVO-ME patients(28 males;32 females),aged 50-78y(mean 63.3±7.6y)and 60 age-/sex-matched healthy controls.As compared with participants exhibiting normal funduscopic findings,CRVO patients demonstrated significantly elevated levels of low-shear-rate whole blood viscosity(LSR-WBV),high-shearrate whole blood viscosity(HSR-WBV),and aggregation index(AI,all P<0.05).In CRVO-affected eyes,vertical cupto-disc(C/D)ratio and optic cup volume were significantly smaller,whereas retinal nerve fiber layer(RNFL)thickness was significantly greater,compared to both unaffected contralateral eyes and normal control eyes(all P<0.05).Following treatment,VD of the entire optic disc(P<0.05),intra-disc VD(P<0.05),and peripapillary VD(P<0.05)all increased significantly relative to baseline.CMT decreased significantly(P<0.05),whereas macular SCP-VD and macular DCP-VD showed non-significant slight reductions(P>0.05).At baseline,BCVA of CRVO eyes correlated with whole-disc VD(r=-0.276,P=0.033),intra-disc VD(r=-0.342,P=0.009),and peripapillary VD(r=-0.335,P=0.007),with intra-disc VD demonstrating the strongest association.Besides,BCVA improvement,after the treatment,correlated positively with whole-disc VD(r=0.342,P=0.008)and intradisc VD(r=0.396,P=0.002).CONCLUSION:Optic disc blood perfusion is more closely associated with visual acuity than macular perfusion,suggesting intra-disc VD may serve as a potential biomarker for monitoring visual acuity changes in CRVO.Multiple ranibizumab injections significantly improve optic disc perfusion but may have exerted detrimental effects on the macula.CRVO patients shows higher hemorheological parameters than those with normal fundi.Reduced vertical C/D ratio and optic cup volume may be linked to CRVO incidence,potentially acting as susceptibility factors.展开更多
AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control...AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.展开更多
AIM:To compare the cup-to-disc ratio(CDR)and optic disc morphology between eyes with congenital cataract and eyes without cataract in children under 3 years old.METHODS:This study included 63 patients with bilateral c...AIM:To compare the cup-to-disc ratio(CDR)and optic disc morphology between eyes with congenital cataract and eyes without cataract in children under 3 years old.METHODS:This study included 63 patients with bilateral congenital cataract(mean age of 55.72±46.50wk,44 were male),33 patients with unilateral cataract(mean age of 56.63±33.23wk,16 were male),and 31 age-matched healthy children(mean age of 55.80±29.29wk,17 were male).Fundus photographs were taken with the RetCam 3 system.The horizontal-to-vertical disc diameter ratio(HVDR)was used as an index to describe the oval form of the optic disc.RESULTS:The horizontal cup-to-disc ratio(HCDR),vertical cup-to-disc ratio(VCDR)and HVDR of cataract eyes in unilateral groups were significantly smaller than those of the normal eyes(P<0.05).In the unilateral group,the HCDR,VCDR and HVDR of cataract eyes were significantly smaller than those in fellow eyes(P<0.05).The HVDR of eyes in the bilateral group was significantly smaller than those in the age-matched normal eyes(P<0.001).The form of optic disc of the cataract eyes in both the bilateral and unilateral groups was more vertical-oral than the normal eyes in the unilateral and the age-matched groups(P<0.05).CONCLUSION:Our results show that eyes with congenital cataract has a smaller HVDR and the form of the optic disc tended to be vertical-oval in young children.展开更多
The paper presents second approximation model for optical head in super high-density storage technology firstly and it is an important part for three grades approximate model of ultra-small-size quantum well corn-shap...The paper presents second approximation model for optical head in super high-density storage technology firstly and it is an important part for three grades approximate model of ultra-small-size quantum well corn-shaped laser and simulative calculations. It supplies the important and useful results for the NFOD optical head design with ultra thin active layer and ultra small spot laser.展开更多
AIM:To explore changes in the optic disc and peripapillary atrophy(PPA)in school-age children with ametropia using color fundus photography combined with artificial intelligence(AI)technology.METHODS:Based on the retr...AIM:To explore changes in the optic disc and peripapillary atrophy(PPA)in school-age children with ametropia using color fundus photography combined with artificial intelligence(AI)technology.METHODS:Based on the retrospective case-controlled study,226 eyes of 113 children aged aged 6–12y were enrolled from October 2021 to May 2022.According to the results of spherical equivalent(SE),the children were divided into four groups:low myopia group(66 eyes),moderate myopia group(60 eyes),high myopia group(50 eyes)and emmetropia control group(50 eyes).All subjects underwent un-aided visual acuity,dilated pupil optometry,best-corrected visual acuity(BCVA),intraocular pressure,ocular axis measurement and color fundus photography.RESULTS:The width of PPA,horizontal diameter ratio of PPA to the optic disc and area ratio of PPA to the optic disc were significantly different among the four groups(P<0.05).The width of the nasal and temporal neuroretinal rim,the roundness of the optic disc,the height of PPA,the vertical diameter ratio of PPA to the optic disc,and the average density of PPA in the high myopia group were significantly different compared with the other three groups(P<0.05).There were strong negative correlations between SE and area ratio of PPA to the optic disc(r=-0.812,P<0.001)and strong positive correlation between axial length(AL)and area ratio of PPA to the optic disc(r=0.736,P<0.001).CONCLUSION:In school-age children with high myopia,the nasal and temporal neuroretinal rims are narrowed and even lost,which have high sensitivity.The area ratio of the PPA to the optic disc could be used as an early predictor of myopia progression,which is of great significance for the development prevention and management of myopia.展开更多
Myopia,a worldwide condition,is a multifactorial disease resulting in many ocular complications.Early onset of myopia has a great tendency to develop high myopia and pathological myopia later in life.The pathophysiolo...Myopia,a worldwide condition,is a multifactorial disease resulting in many ocular complications.Early onset of myopia has a great tendency to develop high myopia and pathological myopia later in life.The pathophysiology and progression of myopia is still unclear.Owing to its involving in visual function,optic disc and peripapillary change in high myopia can＇t be neglected,and it may help in better understanding of the pathophysiology or mechanism of myopia progression.Recently,advanced imaging techniques have been developed,such as optical coherence tomography（OCT）,allowing for better detecting of optic disc and peripapillary change.OCT is a highresolution and noninvasive measurement for detection of ocular structure.Herein,we provide an updated review of optic disc and peripapillary change in OCT image,including its characteristics and clinical significance.We also propose some problems needed further investigation.展开更多
In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR i...In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR is a reliable measure for the early diagnosis of Glaucoma.In this study,we developed a lightweight DNN model for OC and OD segmentation in retinal fundus images.Our DNN model is based on modifications to Anam-Net,incorporating an anamorphic depth embedding block.To reduce computational complexity,we employ a fixed filter size for all convolution layers in the encoder and decoder stages as the network deepens.This modification significantly reduces the number of trainable parameters,making the model lightweight and suitable for resource-constrained applications.We evaluate the performance of the developed model using two publicly available retinal image databases,namely RIM-ONE and Drishti-GS.The results demonstrate promising OC segmentation performance across most standard evaluation metrics while achieving analogous results for OD segmentation.We used two retinal fundus image databases named RIM-ONE and Drishti-GS that contained 159 images and 101 retinal images,respectively.For OD segmentation using the RIM-ONE we obtain an f1-score(F1),Jaccard coefficient(JC),and overlapping error(OE)of 0.950,0.9219,and 0.0781,respectively.Similarly,for OC segmentation using the same databases,we achieve scores of 0.8481(F1),0.7428(JC),and 0.2572(OE).Based on these experimental results and the significantly lower number of trainable parameters,we conclude that the developed model is highly suitable for the early diagnosis of glaucoma by accurately estimating the CDR.展开更多
Glaucoma is an eye disease that usually occurs with the increased Intra-Ocular Pressure(IOP),which damages the vision of eyes.So,detecting and classifying Glaucoma is an important and demanding task in recent days.For...Glaucoma is an eye disease that usually occurs with the increased Intra-Ocular Pressure(IOP),which damages the vision of eyes.So,detecting and classifying Glaucoma is an important and demanding task in recent days.For this purpose,some of the clustering and segmentation techniques are proposed in the existing works.But,it has some drawbacks that include ineficient,inaccurate and estimates only the affected area.In order to solve these issues,a Neighboring Differential Clustering(NDC)-Intensity V ariation Making(IVM)are proposed in this paper.The main intention of this work is to extract and diagnose the abnormal retinal image by identifying the optic disc.This work includes three stages such as,preprocessing,clustering and segmentation.At first,the given retinal image is preprocessed by using the Gaussian Mask Updated(GMU)model for eliminating the noise and improving the quality of the image.Then,the cluster is formed by extracting the threshold and patterns with the help of NDC technique.In the segmentation stage,the weight is calculated for pixel matching and ROI extraction by using the proposed IVM method.Here,the novelty is presented in the clustering and segmentation processes by developing NDC and IVM algorithms for accurate Glaucoma identification.In experiments,the results of both existing and proposed techniques are evaluated in terms of sensitivity,specificity,accuracy,Hausdorff distance,Jaccard and dice metrics.展开更多
Glaucoma disease causes irreversible damage to the optical nerve and it has the potential to cause permanent loss of vision.Glaucoma ranks as the second most prevalent cause of permanent blindness.Traditional glaucoma...Glaucoma disease causes irreversible damage to the optical nerve and it has the potential to cause permanent loss of vision.Glaucoma ranks as the second most prevalent cause of permanent blindness.Traditional glaucoma diagnosis requires a highly experienced specialist,costly equipment,and a lengthy wait time.For automatic glaucoma detection,state-of-the-art glaucoma detection methods include a segmentation-based method to calculate the cup-to-disc ratio.Other methods include multi-label segmentation networks and learning-based methods and rely on hand-crafted features.Localizing the optic disc(OD)is one of the key features in retinal images for detecting retinal diseases,especially for glaucoma disease detection.The approach presented in this study is based on deep classifiers for OD segmentation and glaucoma detection.First,the optic disc detection process is based on object detection using a Mask Region-Based Convolutional Neural Network(Mask-RCNN).The OD detection task was validated using the Dice score,intersection over union,and accuracy metrics.The OD region is then fed into the second stage for glaucoma detection.Therefore,considering only the OD area for glaucoma detection will reduce the number of classification artifacts by limiting the assessment to the optic disc area.For this task,VGG-16(Visual Geometry Group),Resnet-18(Residual Network),and Inception-v3 were pre-trained and fine-tuned.We also used the Support Vector Machine Classifier.The feature-based method uses region content features obtained by Histogram of Oriented Gradients(HOG)and Gabor Filters.The final decision is based on weighted fusion.A comparison of the obtained results from all classification approaches is provided.Classification metrics including accuracy and ROC curve are compared for each classification method.The novelty of this research project is the integration of automatic OD detection and glaucoma diagnosis in a global method.Moreover,the fusion-based decision system uses the glaucoma detection result obtained using several convolutional deep neural networks and the support vector machine classifier.These classification methods contribute to producing robust classification results.This method was evaluated using well-known retinal images available for research work and a combined dataset including retinal images with and without pathology.The performance of the models was tested on two public datasets and a combined dataset and was compared to similar research.The research findings show the potential of this methodology in the early detection of glaucoma,which will reduce diagnosis time and increase detection efficiency.The glaucoma assessment achieves about 98%accuracy in the classification rate,which is close to and even higher than that of state-of-the-art methods.The designed detection model may be used in telemedicine,healthcare,and computer-aided diagnosis systems.展开更多
AIMTo evaluate the possible relationship of optic disc area with retina nerve fiber layer in different glaucoma subtypes.METHODSOne eye each was chosen from 45 patients with ocular hypertension, 45 patients with prima...AIMTo evaluate the possible relationship of optic disc area with retina nerve fiber layer in different glaucoma subtypes.METHODSOne eye each was chosen from 45 patients with ocular hypertension, 45 patients with primary open angle glaucoma, 45 patients with pseudoexfoliation glaucoma and 45 healthy controls followed in our hospital. The records of the patients were reviewed retrospectively. Optic disc area and circumpapillary retina nerve fiber layer measurements were obtained using optical coherence tomography. Central corneal thickness was measured by ultrasound pachymetry.RESULTSThe median disc area in the patients with primary open angle glaucoma was significantly higher than the patients with ocular hypertension (2.19 vs 1.90 mm<sup>2</sup>, P=0.030). The median retina nerve fiber layer was thinner in the patients with primary open angle glaucoma and pseudoexfoliation glaucoma than the patients with ocular hypertension for superior, inferior and temporal quadrants. After adjustment for age, no difference in central corneal thickness was found between the groups. Greater disc area was associated with thicker retinal nerve fiber layer for superior, inferior and nasal quadrants in the patients with primary open angle glaucoma. There was no correlation between disc area and central corneal thickness measurements of the groups.CONCLUSIONDisc size affects the retinal nerve fiber layer thickness in eyes with primary open angle glaucoma and is a possible risk factor for glaucomatous optic nerve damage.展开更多
Dear Editor,We present the first reported case of nasal optic disc pit resulting in serous detachment of the macula. Optic disc pit is a rare congenital anomaly occurring in one out of 11 000 people. The appearance is...Dear Editor,We present the first reported case of nasal optic disc pit resulting in serous detachment of the macula. Optic disc pit is a rare congenital anomaly occurring in one out of 11 000 people. The appearance is a localized round or oval depression in that is grey, yellow or black in colour depending on the amount of glial tissue present.展开更多
Optical coherence tomography(OCT)is an ocular imaging technique that can complement the neuro-ophthalmic assessment,and inform our understanding regarding functional consequences of neuroaxonal injury in the afferent ...Optical coherence tomography(OCT)is an ocular imaging technique that can complement the neuro-ophthalmic assessment,and inform our understanding regarding functional consequences of neuroaxonal injury in the afferent visual pathway.Indeed,OCT has emerged as a surrogate end-point in the diagnosis and follow up of several demyelinating syndromes of the central nervous system(CNS),including optic neuritis(ON)associated with:multiple sclerosis(MS),neuromyelitis optica spectrum disorder(NMOSD),and anti-myelin oligodendrocyte glycoprotein(MOG)antibodies.Recent advancements in enhanced depth imaging(EDI)OCT have distinguished this technique as a new gold standard in the diagnosis of optic disc drusen(ODD).Moreover,OCT may enhance our ability to distinguish cases of papilledema from pseudopapilledema caused by ODD.In the setting of idiopathic intracranial hypertension(IIH),OCT has shown benefit in tracking responses to treatment,with respect to reduced retinal nerve fiber layer(RNFL)measures and morphological changes in the angling of Bruch’s membrane.Longitudinal follow up of OCT measured ganglion cell-inner plexiform layer thickness may be of particular value in managing IIH patients who have secondary optic atrophy.Causes of compressive optic neuropathies may be readily diagnosed with OCT,even in the absence of overt visual field defects.Furthermore,OCT values may offer some prognostic value in predicting post-operative outcomes in these patients.Finally,OCT can be indispensable in differentiating optic neuropathies from retinal diseases in patients presenting with vision loss,and an unrevealing fundus examination.In this review,our over-arching goal is to highlight the potential role of OCT,as an ancillary investigation,in the diagnosis and management of various optic nerve disorders.展开更多
AIM: To assess the association between buried optic disc drusen(BODD) location using spectral-domain optical coherence tomography(SD-OCT) and the location of associated visual field defects(VFD) using the Garway-Heath...AIM: To assess the association between buried optic disc drusen(BODD) location using spectral-domain optical coherence tomography(SD-OCT) and the location of associated visual field defects(VFD) using the Garway-Heath mapping.METHODS: This monocentric retrospective crosssectional study was led at the authors’ institution. Adult patients diagnosed with BODD who had complete records with a reliable Humphrey? 24-2 visual field, macular, and papillary OCT were enrolled. Fisher’s exact test was used to measure the association between BODD location and VFD distribution according to Garway-Heath’s mapping.RESULTS: Totally 20 eyes of 15 patients were included(60% females). The median age(interquartile range) was 63(43)y and the median best corrected visual acuity(BCVA) was-0.08(0.08) log MAR. BODD were mostly located in zones A, E, and F. The minimal rim width(MRW) was globally preserved. The retinal nerve fiber layer(RNFL) was predominantly altered in zones D, E, and F. There was a significant correlation between BODD location and that of RNFL alterations in zones D(P=0.03) and E(P=0.025);Moreover, the presence of BODD in the E zone was significantly related to damaged RNFL in the neighbouring sectors D and F(P=0.012;P=0.02 respectively). Sixty-three percent(12/19) of visual fields were abnormal and there was a significant match(Phi=0.7, P=0.009) between drusen location and VFD only in zone D.CONCLUSION: BODD do not only affect young patients and can be more harmful than usually expected, as we found VFD in 63% of cases. There is a correspondence between BODD location, RNFL damage, and VFD distributions. The presence of BODD induces the overestimation of MRW,thereby disrupting its sensitivity as an early indicator of ganglion fibers damage.展开更多
AIM:To evaluate concordance between the clinical assessment of glaucomatous progression of the optic disc photography and progression identified by Heidelberg Retina Tomograph(HRT)in patients with suspected primary ju...AIM:To evaluate concordance between the clinical assessment of glaucomatous progression of the optic disc photography and progression identified by Heidelberg Retina Tomograph(HRT)in patients with suspected primary juvenile open angle glaucoma(JOAG).METHODS:Optic disc photographs and corresponding HRTⅡseries were reviewed.Optic disc changes between first and final photographs were noted as well as progression identified by HRT topographic change analysis(TCA)and rim area regression line(RARL)Agreement between progression indentified by photography and HRT methods was assessed.Progression,determined from optic disc photographs by consensus assessment was used as the reference standard.RESULTS:A total of 31 patients(59 eyes)with suspected JOAG were studied.Agreement for progression/no progression between TCA and photography was obtained in 4 progressing eyes and 38stable eyes(71.19%,k=0.11).Agreement for progression/no progression between RARL and photography was detected in 5 progressing eyes and in 34 stable eyes(66.10%,k=0.15).The number of HRT per patient was statistically higher in the progressing group(P=0.034).CONCLUSION:Agreement for detection of longitudinal changes between photography and HRT analysis was poor.One way to improve the chance of discovery of the progression could be increasing the number of HRT examinations.展开更多
We present, to the authors＇ knowledge, the first reported case of an optic disc pit （ODP） and retinal cavernous hemangioma （RCH） in the same eye in addition to a review of both clinical entities. An ODP is a rare...We present, to the authors＇ knowledge, the first reported case of an optic disc pit （ODP） and retinal cavernous hemangioma （RCH） in the same eye in addition to a review of both clinical entities. An ODP is a rare congenital or acquired cavitary defect in the optic nerve head.展开更多
Dear Editor,We present the first reported case of unilateral optic disc swelling with subsequent persistent loss of vision triggered by ecstasy consumption in the case of a young man.Ecstasy is one of the most commonl...Dear Editor,We present the first reported case of unilateral optic disc swelling with subsequent persistent loss of vision triggered by ecstasy consumption in the case of a young man.Ecstasy is one of the most commonly consumed recreational drugs among young adults.Its main constituent and active substance is 3,4-methylenedioxymethamphetamine(MDMA).展开更多
BACKGROUND To report an unusual case of bilateral optic disc coloboma associated with macular retinoschisis in the left eye.CASE SUMMARY A 37-year-old woman presented with complaints of blurred and distorted vision in...BACKGROUND To report an unusual case of bilateral optic disc coloboma associated with macular retinoschisis in the left eye.CASE SUMMARY A 37-year-old woman presented with complaints of blurred and distorted vision in her left eye for more than 1 year.Fundus examination demonstrated choroidal atrophy around the optic disc in both eyes,with a cup-to-disc ratio of 0.9.Serous retinal detachment in the macular area of the left eye.Left eye macular blood flow imaging optical coherence tomography(Angio-OCT)showed macular retinal serous cleavage.En-face OCT showed that the canal gully-like structure formed by the defect of the optic disc nerve fiber layer between the optic disc and macula,serous detachment area was connected with the enlarged optic disc coloboma through the canal gully-like structure,and the fluid leaked from the enlarged and thinned optic disc coloboma into the retinal layer of the macular area.Patients with optic disc abnormalities and macular degeneration must be monitored appropriately.During the follow-up period,the use of optic disc stereography and 3D-OCT,en-face,and Angio-OCT imaging can clarify the correlation between macular retinoschisis and optic disc coloboma.CONCLUSION Macular retinoschisis may be owing to the combined force of disc edge loss,enlarged optic disc coloboma,the canal gully-like structure formed by the defect of the nerve fiber layer around the optic disc,and the traction of the posterior vitreous cortex.展开更多
In recent days,detecting Optic Disc(OD)in retinal images has been challenging and very important to the early diagnosis of eye diseases.The process of detecting the OD is challenging due to the diversity of color,inte...In recent days,detecting Optic Disc(OD)in retinal images has been challenging and very important to the early diagnosis of eye diseases.The process of detecting the OD is challenging due to the diversity of color,intensity,brightness and shape of the OD.Moreover,the color similarities of the neighboring organs of the OD create difficulties during OD detection.In the proposed Fuzzy K‒Means Threshold(FKMT)and Morphological Operation with Pixel Density Feature(MOPDF),the input retinal images are coarsely segmented by fuzzy K‒means clustering and thresholding,in which the OD is classified from its neighboring organs with intensity similarities.Then,the segmented images are given as the input to morphological operation with pixel density feature calculations,which reduce the false detection in the small pixel of the OD.Finally,the OD area is detected by applying the Sobel edge detection method,which accurately detects the OD from the retinal images.After detection optimization,the proposed method achieved Sensitivity(SEN),Specificity(SPEC)and Accuracy(ACC),with 96.74%,96.78%and 96.92%in DiaretDB0(Standard Diabetic Retinopathy Database Calibration level 0),97.12%,97.10%and 97.75%in DiaretDB1(Standard Diabetic Retinopathy Database Calibration level 1)and 97.19%,97.47%and 97.43%in STARE(Structured Analysis of the Retina)dataset respectively.The experimental results demonstrated the proposed method’s efficiency for segmenting and detecting OD areas.展开更多
Optical coherence tomography(OCT)is a widely used non-invasive medical imaging technology that has revolutionized clinical care in ophthalmology.New developments,such as OCT angiography(OCTA)are expected to contribute...Optical coherence tomography(OCT)is a widely used non-invasive medical imaging technology that has revolutionized clinical care in ophthalmology.New developments,such as OCT angiography(OCTA)are expected to contribute even further to the widespread use of OCT-based imaging devices in the diagnosis and monitoring of patients with ophthalmic diseases.In recent years,many of the disadvantages such as limited field of view and imaging artefacts have been substantially reduced.Similar to the progress achieved in the assessment of retinal disorders,OCT is expected to change the approach to patients seen in the neuro-ophthalmology clinic.In this article,we review the technical features of OCT and OCT-based imaging techniques,highlighting the specific factors that should be taken into account when interpreting OCT in the field of neuro-ophthalmology.展开更多
文摘Scanning tunneling microscope (STM) is used to investigate the optical disc.The areas with and without data stampers are all observed carefully. Three-dimensional images of the disc surface clearly demonstrate the period, depth of the grooves and the shape of data stampers. Some phenomena of STM imaging are also discussed.
基金Central High-Level Traditional Chinese Medicine Hospital Project of Eye Hospital China Academy of Chinese Medical Science(No.GSP5-83,No.GSP4-02No.GSP5-06)+1 种基金Supported by National Natural Science Foundation of China(General ProgramNo.82474582).
文摘AIM:To evaluate the therapeutic effects of ranibizumab on optic disc and macular microvascular perfusion in central retinal vein occlusion(CRVO)with macular edema(ME).METHODS:Optical coherence tomography angiology(OCTA)parameters,including optic disc vessel density(VD;including whole-disc VD,intra-disc VD,and peripapillary VD),superficial/deep capillary plexus(SCP/DCP)VD,and central macular thickness(CMT)were analyzed.Additional assessments included best-corrected visual acuity(BCVA)via Early Treatment Diabetic Retinopathy Study(ETDRS)chart and hemorheological profiling.CRVO patients received monthly intravitreal ranibizumab injections for three consecutive months.Pre-and post-treatment parameters were statistically compared.RESULTS:The study comprised 60 CRVO-ME patients(28 males;32 females),aged 50-78y(mean 63.3±7.6y)and 60 age-/sex-matched healthy controls.As compared with participants exhibiting normal funduscopic findings,CRVO patients demonstrated significantly elevated levels of low-shear-rate whole blood viscosity(LSR-WBV),high-shearrate whole blood viscosity(HSR-WBV),and aggregation index(AI,all P<0.05).In CRVO-affected eyes,vertical cupto-disc(C/D)ratio and optic cup volume were significantly smaller,whereas retinal nerve fiber layer(RNFL)thickness was significantly greater,compared to both unaffected contralateral eyes and normal control eyes(all P<0.05).Following treatment,VD of the entire optic disc(P<0.05),intra-disc VD(P<0.05),and peripapillary VD(P<0.05)all increased significantly relative to baseline.CMT decreased significantly(P<0.05),whereas macular SCP-VD and macular DCP-VD showed non-significant slight reductions(P>0.05).At baseline,BCVA of CRVO eyes correlated with whole-disc VD(r=-0.276,P=0.033),intra-disc VD(r=-0.342,P=0.009),and peripapillary VD(r=-0.335,P=0.007),with intra-disc VD demonstrating the strongest association.Besides,BCVA improvement,after the treatment,correlated positively with whole-disc VD(r=0.342,P=0.008)and intradisc VD(r=0.396,P=0.002).CONCLUSION:Optic disc blood perfusion is more closely associated with visual acuity than macular perfusion,suggesting intra-disc VD may serve as a potential biomarker for monitoring visual acuity changes in CRVO.Multiple ranibizumab injections significantly improve optic disc perfusion but may have exerted detrimental effects on the macula.CRVO patients shows higher hemorheological parameters than those with normal fundi.Reduced vertical C/D ratio and optic cup volume may be linked to CRVO incidence,potentially acting as susceptibility factors.
文摘AIM:To compare superficial and deep vascular properties of optic discs between crowded discs and controls using optical coherence tomography angiography(OCT-A).METHODS:Thirty patients with crowded discs,and 47 control subjects were enrolled in the study.One eye of each individual was included and OCT-A scans of optic discs were obtained in a 4.5×4.5 mm^(2) rectangular area.Radial peripapillary capillary(RPC)density,peripapillary retinal nerve fiber layer(pRNFL)thickness,cup volume,rim area,disc area,cup-to-disc(c/d)area ratio,and vertical c/d ratio were obtained automatically using device software.Automated parapapillary choroidal microvasculature(PPCMv)density was calculated using MATLAB software.When the vertical c/d ratio of the optic disc was absent or small cup,it was considered as a crowded disc.RESULTS:The mean signal strength index of OCT-A images was similar between the crowded discs and control eyes(P=0.740).There was no difference in pRNFL between the two groups(P=0.102).There were no differences in RPC density in whole image(P=0.826)and peripapillary region(P=0.923),but inside disc RPC density was higher in crowded optic discs(P=0.003).The PPCMv density in the inner-hemisuperior region was also lower in crowded discs(P=0.026).The pRNFL thickness was positively correlated with peripapillary RPC density(r=0.498,P<0.001).The inside disc RPC density was negatively correlated with c/d area ratio(r=-0.341,P=0.002).CONCLUSION:The higher inside disc RPC density and lower inner-hemisuperior PPCMv density are found in eyes with crowded optic discs.
文摘AIM:To compare the cup-to-disc ratio(CDR)and optic disc morphology between eyes with congenital cataract and eyes without cataract in children under 3 years old.METHODS:This study included 63 patients with bilateral congenital cataract(mean age of 55.72±46.50wk,44 were male),33 patients with unilateral cataract(mean age of 56.63±33.23wk,16 were male),and 31 age-matched healthy children(mean age of 55.80±29.29wk,17 were male).Fundus photographs were taken with the RetCam 3 system.The horizontal-to-vertical disc diameter ratio(HVDR)was used as an index to describe the oval form of the optic disc.RESULTS:The horizontal cup-to-disc ratio(HCDR),vertical cup-to-disc ratio(VCDR)and HVDR of cataract eyes in unilateral groups were significantly smaller than those of the normal eyes(P<0.05).In the unilateral group,the HCDR,VCDR and HVDR of cataract eyes were significantly smaller than those in fellow eyes(P<0.05).The HVDR of eyes in the bilateral group was significantly smaller than those in the age-matched normal eyes(P<0.001).The form of optic disc of the cataract eyes in both the bilateral and unilateral groups was more vertical-oral than the normal eyes in the unilateral and the age-matched groups(P<0.05).CONCLUSION:Our results show that eyes with congenital cataract has a smaller HVDR and the form of the optic disc tended to be vertical-oval in young children.
基金Supported by the National Natural Science Foundation of China and Doctor Foundation of China
文摘The paper presents second approximation model for optical head in super high-density storage technology firstly and it is an important part for three grades approximate model of ultra-small-size quantum well corn-shaped laser and simulative calculations. It supplies the important and useful results for the NFOD optical head design with ultra thin active layer and ultra small spot laser.
文摘AIM:To explore changes in the optic disc and peripapillary atrophy(PPA)in school-age children with ametropia using color fundus photography combined with artificial intelligence(AI)technology.METHODS:Based on the retrospective case-controlled study,226 eyes of 113 children aged aged 6–12y were enrolled from October 2021 to May 2022.According to the results of spherical equivalent(SE),the children were divided into four groups:low myopia group(66 eyes),moderate myopia group(60 eyes),high myopia group(50 eyes)and emmetropia control group(50 eyes).All subjects underwent un-aided visual acuity,dilated pupil optometry,best-corrected visual acuity(BCVA),intraocular pressure,ocular axis measurement and color fundus photography.RESULTS:The width of PPA,horizontal diameter ratio of PPA to the optic disc and area ratio of PPA to the optic disc were significantly different among the four groups(P<0.05).The width of the nasal and temporal neuroretinal rim,the roundness of the optic disc,the height of PPA,the vertical diameter ratio of PPA to the optic disc,and the average density of PPA in the high myopia group were significantly different compared with the other three groups(P<0.05).There were strong negative correlations between SE and area ratio of PPA to the optic disc(r=-0.812,P<0.001)and strong positive correlation between axial length(AL)and area ratio of PPA to the optic disc(r=0.736,P<0.001).CONCLUSION:In school-age children with high myopia,the nasal and temporal neuroretinal rims are narrowed and even lost,which have high sensitivity.The area ratio of the PPA to the optic disc could be used as an early predictor of myopia progression,which is of great significance for the development prevention and management of myopia.
基金Supported by the National Key Project of Research and Development Plan(No.2017YFA0104101)
文摘Myopia,a worldwide condition,is a multifactorial disease resulting in many ocular complications.Early onset of myopia has a great tendency to develop high myopia and pathological myopia later in life.The pathophysiology and progression of myopia is still unclear.Owing to its involving in visual function,optic disc and peripapillary change in high myopia can＇t be neglected,and it may help in better understanding of the pathophysiology or mechanism of myopia progression.Recently,advanced imaging techniques have been developed,such as optical coherence tomography（OCT）,allowing for better detecting of optic disc and peripapillary change.OCT is a highresolution and noninvasive measurement for detection of ocular structure.Herein,we provide an updated review of optic disc and peripapillary change in OCT image,including its characteristics and clinical significance.We also propose some problems needed further investigation.
基金funded byResearchers Supporting Project Number(RSPD2024R 553),King Saud University,Riyadh,Saudi Arabia.
文摘In this work,we aim to introduce some modifications to the Anam-Net deep neural network(DNN)model for segmenting optic cup(OC)and optic disc(OD)in retinal fundus images to estimate the cup-to-disc ratio(CDR).The CDR is a reliable measure for the early diagnosis of Glaucoma.In this study,we developed a lightweight DNN model for OC and OD segmentation in retinal fundus images.Our DNN model is based on modifications to Anam-Net,incorporating an anamorphic depth embedding block.To reduce computational complexity,we employ a fixed filter size for all convolution layers in the encoder and decoder stages as the network deepens.This modification significantly reduces the number of trainable parameters,making the model lightweight and suitable for resource-constrained applications.We evaluate the performance of the developed model using two publicly available retinal image databases,namely RIM-ONE and Drishti-GS.The results demonstrate promising OC segmentation performance across most standard evaluation metrics while achieving analogous results for OD segmentation.We used two retinal fundus image databases named RIM-ONE and Drishti-GS that contained 159 images and 101 retinal images,respectively.For OD segmentation using the RIM-ONE we obtain an f1-score(F1),Jaccard coefficient(JC),and overlapping error(OE)of 0.950,0.9219,and 0.0781,respectively.Similarly,for OC segmentation using the same databases,we achieve scores of 0.8481(F1),0.7428(JC),and 0.2572(OE).Based on these experimental results and the significantly lower number of trainable parameters,we conclude that the developed model is highly suitable for the early diagnosis of glaucoma by accurately estimating the CDR.
文摘Glaucoma is an eye disease that usually occurs with the increased Intra-Ocular Pressure(IOP),which damages the vision of eyes.So,detecting and classifying Glaucoma is an important and demanding task in recent days.For this purpose,some of the clustering and segmentation techniques are proposed in the existing works.But,it has some drawbacks that include ineficient,inaccurate and estimates only the affected area.In order to solve these issues,a Neighboring Differential Clustering(NDC)-Intensity V ariation Making(IVM)are proposed in this paper.The main intention of this work is to extract and diagnose the abnormal retinal image by identifying the optic disc.This work includes three stages such as,preprocessing,clustering and segmentation.At first,the given retinal image is preprocessed by using the Gaussian Mask Updated(GMU)model for eliminating the noise and improving the quality of the image.Then,the cluster is formed by extracting the threshold and patterns with the help of NDC technique.In the segmentation stage,the weight is calculated for pixel matching and ROI extraction by using the proposed IVM method.Here,the novelty is presented in the clustering and segmentation processes by developing NDC and IVM algorithms for accurate Glaucoma identification.In experiments,the results of both existing and proposed techniques are evaluated in terms of sensitivity,specificity,accuracy,Hausdorff distance,Jaccard and dice metrics.
基金Deanship of Scientific Research,Princess Nourah bint Abdulrahman University,through the Program of Research Project Funding after Publication,Grant No(43-PRFA-P-31).
文摘Glaucoma disease causes irreversible damage to the optical nerve and it has the potential to cause permanent loss of vision.Glaucoma ranks as the second most prevalent cause of permanent blindness.Traditional glaucoma diagnosis requires a highly experienced specialist,costly equipment,and a lengthy wait time.For automatic glaucoma detection,state-of-the-art glaucoma detection methods include a segmentation-based method to calculate the cup-to-disc ratio.Other methods include multi-label segmentation networks and learning-based methods and rely on hand-crafted features.Localizing the optic disc(OD)is one of the key features in retinal images for detecting retinal diseases,especially for glaucoma disease detection.The approach presented in this study is based on deep classifiers for OD segmentation and glaucoma detection.First,the optic disc detection process is based on object detection using a Mask Region-Based Convolutional Neural Network(Mask-RCNN).The OD detection task was validated using the Dice score,intersection over union,and accuracy metrics.The OD region is then fed into the second stage for glaucoma detection.Therefore,considering only the OD area for glaucoma detection will reduce the number of classification artifacts by limiting the assessment to the optic disc area.For this task,VGG-16(Visual Geometry Group),Resnet-18(Residual Network),and Inception-v3 were pre-trained and fine-tuned.We also used the Support Vector Machine Classifier.The feature-based method uses region content features obtained by Histogram of Oriented Gradients(HOG)and Gabor Filters.The final decision is based on weighted fusion.A comparison of the obtained results from all classification approaches is provided.Classification metrics including accuracy and ROC curve are compared for each classification method.The novelty of this research project is the integration of automatic OD detection and glaucoma diagnosis in a global method.Moreover,the fusion-based decision system uses the glaucoma detection result obtained using several convolutional deep neural networks and the support vector machine classifier.These classification methods contribute to producing robust classification results.This method was evaluated using well-known retinal images available for research work and a combined dataset including retinal images with and without pathology.The performance of the models was tested on two public datasets and a combined dataset and was compared to similar research.The research findings show the potential of this methodology in the early detection of glaucoma,which will reduce diagnosis time and increase detection efficiency.The glaucoma assessment achieves about 98%accuracy in the classification rate,which is close to and even higher than that of state-of-the-art methods.The designed detection model may be used in telemedicine,healthcare,and computer-aided diagnosis systems.
文摘AIMTo evaluate the possible relationship of optic disc area with retina nerve fiber layer in different glaucoma subtypes.METHODSOne eye each was chosen from 45 patients with ocular hypertension, 45 patients with primary open angle glaucoma, 45 patients with pseudoexfoliation glaucoma and 45 healthy controls followed in our hospital. The records of the patients were reviewed retrospectively. Optic disc area and circumpapillary retina nerve fiber layer measurements were obtained using optical coherence tomography. Central corneal thickness was measured by ultrasound pachymetry.RESULTSThe median disc area in the patients with primary open angle glaucoma was significantly higher than the patients with ocular hypertension (2.19 vs 1.90 mm<sup>2</sup>, P=0.030). The median retina nerve fiber layer was thinner in the patients with primary open angle glaucoma and pseudoexfoliation glaucoma than the patients with ocular hypertension for superior, inferior and temporal quadrants. After adjustment for age, no difference in central corneal thickness was found between the groups. Greater disc area was associated with thicker retinal nerve fiber layer for superior, inferior and nasal quadrants in the patients with primary open angle glaucoma. There was no correlation between disc area and central corneal thickness measurements of the groups.CONCLUSIONDisc size affects the retinal nerve fiber layer thickness in eyes with primary open angle glaucoma and is a possible risk factor for glaucomatous optic nerve damage.
文摘Dear Editor,We present the first reported case of nasal optic disc pit resulting in serous detachment of the macula. Optic disc pit is a rare congenital anomaly occurring in one out of 11 000 people. The appearance is a localized round or oval depression in that is grey, yellow or black in colour depending on the amount of glial tissue present.
文摘Optical coherence tomography(OCT)is an ocular imaging technique that can complement the neuro-ophthalmic assessment,and inform our understanding regarding functional consequences of neuroaxonal injury in the afferent visual pathway.Indeed,OCT has emerged as a surrogate end-point in the diagnosis and follow up of several demyelinating syndromes of the central nervous system(CNS),including optic neuritis(ON)associated with:multiple sclerosis(MS),neuromyelitis optica spectrum disorder(NMOSD),and anti-myelin oligodendrocyte glycoprotein(MOG)antibodies.Recent advancements in enhanced depth imaging(EDI)OCT have distinguished this technique as a new gold standard in the diagnosis of optic disc drusen(ODD).Moreover,OCT may enhance our ability to distinguish cases of papilledema from pseudopapilledema caused by ODD.In the setting of idiopathic intracranial hypertension(IIH),OCT has shown benefit in tracking responses to treatment,with respect to reduced retinal nerve fiber layer(RNFL)measures and morphological changes in the angling of Bruch’s membrane.Longitudinal follow up of OCT measured ganglion cell-inner plexiform layer thickness may be of particular value in managing IIH patients who have secondary optic atrophy.Causes of compressive optic neuropathies may be readily diagnosed with OCT,even in the absence of overt visual field defects.Furthermore,OCT values may offer some prognostic value in predicting post-operative outcomes in these patients.Finally,OCT can be indispensable in differentiating optic neuropathies from retinal diseases in patients presenting with vision loss,and an unrevealing fundus examination.In this review,our over-arching goal is to highlight the potential role of OCT,as an ancillary investigation,in the diagnosis and management of various optic nerve disorders.
文摘AIM: To assess the association between buried optic disc drusen(BODD) location using spectral-domain optical coherence tomography(SD-OCT) and the location of associated visual field defects(VFD) using the Garway-Heath mapping.METHODS: This monocentric retrospective crosssectional study was led at the authors’ institution. Adult patients diagnosed with BODD who had complete records with a reliable Humphrey? 24-2 visual field, macular, and papillary OCT were enrolled. Fisher’s exact test was used to measure the association between BODD location and VFD distribution according to Garway-Heath’s mapping.RESULTS: Totally 20 eyes of 15 patients were included(60% females). The median age(interquartile range) was 63(43)y and the median best corrected visual acuity(BCVA) was-0.08(0.08) log MAR. BODD were mostly located in zones A, E, and F. The minimal rim width(MRW) was globally preserved. The retinal nerve fiber layer(RNFL) was predominantly altered in zones D, E, and F. There was a significant correlation between BODD location and that of RNFL alterations in zones D(P=0.03) and E(P=0.025);Moreover, the presence of BODD in the E zone was significantly related to damaged RNFL in the neighbouring sectors D and F(P=0.012;P=0.02 respectively). Sixty-three percent(12/19) of visual fields were abnormal and there was a significant match(Phi=0.7, P=0.009) between drusen location and VFD only in zone D.CONCLUSION: BODD do not only affect young patients and can be more harmful than usually expected, as we found VFD in 63% of cases. There is a correspondence between BODD location, RNFL damage, and VFD distributions. The presence of BODD induces the overestimation of MRW,thereby disrupting its sensitivity as an early indicator of ganglion fibers damage.
文摘AIM:To evaluate concordance between the clinical assessment of glaucomatous progression of the optic disc photography and progression identified by Heidelberg Retina Tomograph(HRT)in patients with suspected primary juvenile open angle glaucoma(JOAG).METHODS:Optic disc photographs and corresponding HRTⅡseries were reviewed.Optic disc changes between first and final photographs were noted as well as progression identified by HRT topographic change analysis(TCA)and rim area regression line(RARL)Agreement between progression indentified by photography and HRT methods was assessed.Progression,determined from optic disc photographs by consensus assessment was used as the reference standard.RESULTS:A total of 31 patients(59 eyes)with suspected JOAG were studied.Agreement for progression/no progression between TCA and photography was obtained in 4 progressing eyes and 38stable eyes(71.19%,k=0.11).Agreement for progression/no progression between RARL and photography was detected in 5 progressing eyes and in 34 stable eyes(66.10%,k=0.15).The number of HRT per patient was statistically higher in the progressing group(P=0.034).CONCLUSION:Agreement for detection of longitudinal changes between photography and HRT analysis was poor.One way to improve the chance of discovery of the progression could be increasing the number of HRT examinations.
文摘We present, to the authors＇ knowledge, the first reported case of an optic disc pit （ODP） and retinal cavernous hemangioma （RCH） in the same eye in addition to a review of both clinical entities. An ODP is a rare congenital or acquired cavitary defect in the optic nerve head.
文摘Dear Editor,We present the first reported case of unilateral optic disc swelling with subsequent persistent loss of vision triggered by ecstasy consumption in the case of a young man.Ecstasy is one of the most commonly consumed recreational drugs among young adults.Its main constituent and active substance is 3,4-methylenedioxymethamphetamine(MDMA).
文摘BACKGROUND To report an unusual case of bilateral optic disc coloboma associated with macular retinoschisis in the left eye.CASE SUMMARY A 37-year-old woman presented with complaints of blurred and distorted vision in her left eye for more than 1 year.Fundus examination demonstrated choroidal atrophy around the optic disc in both eyes,with a cup-to-disc ratio of 0.9.Serous retinal detachment in the macular area of the left eye.Left eye macular blood flow imaging optical coherence tomography(Angio-OCT)showed macular retinal serous cleavage.En-face OCT showed that the canal gully-like structure formed by the defect of the optic disc nerve fiber layer between the optic disc and macula,serous detachment area was connected with the enlarged optic disc coloboma through the canal gully-like structure,and the fluid leaked from the enlarged and thinned optic disc coloboma into the retinal layer of the macular area.Patients with optic disc abnormalities and macular degeneration must be monitored appropriately.During the follow-up period,the use of optic disc stereography and 3D-OCT,en-face,and Angio-OCT imaging can clarify the correlation between macular retinoschisis and optic disc coloboma.CONCLUSION Macular retinoschisis may be owing to the combined force of disc edge loss,enlarged optic disc coloboma,the canal gully-like structure formed by the defect of the nerve fiber layer around the optic disc,and the traction of the posterior vitreous cortex.
文摘In recent days,detecting Optic Disc(OD)in retinal images has been challenging and very important to the early diagnosis of eye diseases.The process of detecting the OD is challenging due to the diversity of color,intensity,brightness and shape of the OD.Moreover,the color similarities of the neighboring organs of the OD create difficulties during OD detection.In the proposed Fuzzy K‒Means Threshold(FKMT)and Morphological Operation with Pixel Density Feature(MOPDF),the input retinal images are coarsely segmented by fuzzy K‒means clustering and thresholding,in which the OD is classified from its neighboring organs with intensity similarities.Then,the segmented images are given as the input to morphological operation with pixel density feature calculations,which reduce the false detection in the small pixel of the OD.Finally,the OD area is detected by applying the Sobel edge detection method,which accurately detects the OD from the retinal images.After detection optimization,the proposed method achieved Sensitivity(SEN),Specificity(SPEC)and Accuracy(ACC),with 96.74%,96.78%and 96.92%in DiaretDB0(Standard Diabetic Retinopathy Database Calibration level 0),97.12%,97.10%and 97.75%in DiaretDB1(Standard Diabetic Retinopathy Database Calibration level 1)and 97.19%,97.47%and 97.43%in STARE(Structured Analysis of the Retina)dataset respectively.The experimental results demonstrated the proposed method’s efficiency for segmenting and detecting OD areas.
文摘Optical coherence tomography(OCT)is a widely used non-invasive medical imaging technology that has revolutionized clinical care in ophthalmology.New developments,such as OCT angiography(OCTA)are expected to contribute even further to the widespread use of OCT-based imaging devices in the diagnosis and monitoring of patients with ophthalmic diseases.In recent years,many of the disadvantages such as limited field of view and imaging artefacts have been substantially reduced.Similar to the progress achieved in the assessment of retinal disorders,OCT is expected to change the approach to patients seen in the neuro-ophthalmology clinic.In this article,we review the technical features of OCT and OCT-based imaging techniques,highlighting the specific factors that should be taken into account when interpreting OCT in the field of neuro-ophthalmology.
