Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retin...Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retinopathy has traditionally been considered as damage to the retinal microvasculature.However,growing evidence suggests that diabetic retinopathy is a complex neurovascular disorder resulting from dysfunction of the neurovascular unit,which includes both the retinal vascular structures and neural tissues.Diabetic retinopathy is one of the leading causes of blindness and is frequently screened for as part of diabetic ocular screening.However,diabetic corneal neuropathy is commonly overlooked and underdiagnosed,leading to severe ocular surface impairment.Several studies have found that these two conditions tend to occur together,and they share similarities in their pathogenesis pathways,being triggered by a status of chronic hyperglycemia.This review aims to discuss the interconnection between diabetic corneal neuropathy and diabetic retinopathy,whether diabetic corneal neuropathy precedes diabetic retinopathy,as well as the relation between the stage of diabetic retinopathy and the severity of corneal neuropathy.We also endeavor to explore the relevance of a corneal screening in diabetic eyes and the possibility of using corneal nerve measurements to monitor the progression of diabetic retinopathy.展开更多
The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal ...The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal limbus between cornea and scleral,are believed to be crucial for the continuous turnover of the corneal epithelium.The proliferation,migration,and differentiation of the LESCs are modulated by unique physical and chemical futures contained within the microenvironment known as the limbal niche.This niche,composed of nerve terminals,cells,extracellular matrix,vasculature,and signaling molecules,is the home for processes such as proliferation,migration and differentiation.Corneal nerve terminals possess special anatomical structures in the limbal region and basal epithelial cells,and they demonstrate pivotal biological effects in the regulation of the LESC function and corneal epithelium homeostasis.Biological molecules such as neuropeptides,neurotransmitters,and neurotrophic factors play a crucial role in modulating the LESCs phenotype responsible for corneal epithelium homeostasis.This paper will review recent studies on how these nerve derived molecules function in this process and provide clear orientations for future research.展开更多
Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to ass...Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to assess the effect of the widely used fluorescein dye on human corneal endothelial cells(HCEnCs)in vitro at different concentrations and exposure times.Methods:B4G12,an immortalized human corneal endothelium cell line was cultured on pre-coated tissue culture flask with human endothelial-serum free medium(SFM)supplemented with 10 ng/mL basic fibroblast growth factor(bFGF).The fully confluent B4G12 cell monolayers in 96 well plates were treated with water as control,or fluorescein at various concentrations and exposure times.Cell viability was assessed using two techniques:Alamar Blue assay and cell morphology assessment with an inverted phase-contrast microscopy.Results:Short-term exposure to fluorescein(0.01-0.2%)for up to 30 minutes did not affect cell viability.Continuous fluorescein exposure however significantly reduced the viability of the cells with a notable reduction in cell metabolic activity with fluorescein treatments of 0.001%,0.01% and 0.05% for 1 day(and up to 4 days).Conclusions:Short-term exposure to fluorescein for up to 30 minutes in concentrations commonly used in clinical practice did not affect HCEnC viability.However,fluorescein exposure for longer durations can be detrimental to corneal endothelial cell health.Future studies should evaluate the effects of longer-term fluorescein exposure on endothelial function especially in susceptible patients including the elderly and patients with epithelial defects that enable diffusion of fluorescein towards the endothelium.展开更多
AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospec...AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospective study was designed to evaluate 82 eyes from 82 patients,all of whom had a pre-planned RST of 280 to 300μm and normal corneal topography prior to undergoing SMILE surgery.The mean preoperative spherical equivalent(SE)was-4.82±1.30 D.A standard follow-up protocol was conducted between 1 to 6mo postoperatively.Visual outcomes were recorded using uncorrected visual acuity(UCVA)and subjective refraction.The curvature of the anterior and posterior corneal surfaces,as well as the posterior elevation at the thinnest point(PTE)were derived from the Pentacam system.RESULTS:At the final follow-up,the efficacy index was 1.14±0.15,the safety index was 1.20±0.13.The mean preoperative UDVA was 0.78±0.16 logMAR,which improved significantly to-0.07±0.06 logMAR postoperatively(P<0.001).The preoperative mean SE was-4.82±1.30 D,which decreased to-0.14±0.30 D by the last visit.The curvature of the anterior cornea at the flat meridian(AK1)were 42.62±1.02 D preoperatively,38.56±1.37 D and 38.59±1.39 D at 1 and 6mo after operation,respectively.Corresponding measurements at the steep meridian(AK2)were 43.55±1.14 D preoperatively,39.18±1.46 D and 39.22±1.50 D at 1 and 6mo after operation,respectively.Both AK1 and AK2 remained stable at 1 and 6-mo postoperative intervals(P=0.126 and 0.082,respectively).There were no observed changes in the curvature of the posterior cornea at the flat meridian or at the steep meridian,or the PTE before and after surgery.CONCLUSION:SMILE represents a safe and effective procedure for the correction of myopia and astigmatism in eyes featuring a pre-planned RST ranging from 280 to 300μm accompanied by normal corneal topography,on the premise of strict control of surgical indications.展开更多
AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retr...AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retrospective study was conducted on 30 phakic eyes from patients diagnosed with FECD but without clinical edema,and 59 phakic eyes from a control group without corneal alterations.Comprehensive ophthalmic examinations were conducted,including slitlamp biomicroscopy,corneal specular microscopy(CSM),and Scheimpflug tomography.RESULTS:The study encompassed 30 phakic eyes with FECD(mean age 59.8±13.1y)and 59 control eyes(mean age 61.3±7.7y).The best-corrected visual acuity was higher in the control group compared to the FECD group[0(0,0.08)vs 0.05(0,0.15)logMAR;P=0.042].CSM revealed significant differences between the FECD and control groups in several parameters:number of analyzed cells(26±13 vs 135±42,P<0.001),cell density(2049±376 vs 2479±225 cells/mm2,P<0.001),mean cell area[463(434,544)vs 397(383,431)μm2;P<0.001],coefficient of variation(54.8%±18.7%vs 41.0%±7.2%,P<0.001),and hexagonal cells[0(0,47%)vs 47%(40%,53%),P<0.001].Although often used as a clinical parameter for detecting edema,central corneal thickness measured by CSM showed no significant difference between the FECD and control groups(530±57 vs 546±30μm,P=0.179).Significant differences were noted in various Pentacam measurements between the groups.Specifically,parameters like loss of parallel isopachs(13 vs 0 eyes,P<0.001),displacement of the thinnest point(11 vs 0 eyes,P<0.001),posterior focal depression(25 vs 7 eyes,P<0.001),and increased light scatter[21.4(17.6;23.9)vs 18.0(16.8,21.8),P=0.01]were significantly more prevalent in FECD eyes,reflecting the presence of subclinical edema and loss of corneal transparency.CONCLUSION:Scheimpflug tomography allows for an objective assessment of FECD,offering the capability to detect subclinical edema at an early stage,monitor disease progression,and serve as a predictor of corneal decompensation following cataract surgery.展开更多
AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective st...AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective study included patients with thin corneas(preoperative thinnest corneal thickness ranging from 480 to 520μm)who underwent SMILE for myopia or myopic astigmatism.Corneal topography and posterior corneal elevation were assessed using Pentacam HR at three time points:preoperatively,1mo,and 6mo postoperatively.The measured parameters included thinnest point elevation(PTE),posterior maximal elevation(PME),posterior central elevation(PCE),and 24 additional reference points.RESULTS:A total of 106 eyes from 106 patients(age range:18-34)were included in the study.Uncorrected distance visual acuity(UDVA)improved significantly,with a mean logMAR value of-0.07±0.06 at the final follow-up visit.Measurements of posterior corneal elevation showed no significant changes in most points,hemispheres,and meridians at 6mo postoperatively.Notably,only two points,ΔE_(2mm-45°)andΔE_(2mm-90°),exhibited statistically significant elevation changes:the elevation ofΔE_(2mm-45°)increased from-2.3±4.99 to-1.0±5.9μm(P=0.0037),and that ofΔE_(2mm-90°)increased from-16±7.53 to-15±7.4μm(P=0.016).However,these changes were within the measurement error range of the Pentacam HR(±5μm in a 5 mm area).CONCLUSION:SMILE surgery is a safe and stable procedure for correcting myopia or myopic astigmatism in patients with thin corneas,as evidenced by the stability of posterior corneal elevation.展开更多
Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to b...Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.展开更多
巩膜接触镜通常称为巩膜镜,是一种新型的大直径高透氧性硬性眼表接触镜,能够覆盖角膜、角膜缘及部分巩膜。与传统的角膜接触镜(rigid gas permeable,RGP)相比,巩膜镜具有广泛的适应症,能有效减轻疼痛和刺激、维持眼表湿润、促进角膜上...巩膜接触镜通常称为巩膜镜,是一种新型的大直径高透氧性硬性眼表接触镜,能够覆盖角膜、角膜缘及部分巩膜。与传统的角膜接触镜(rigid gas permeable,RGP)相比,巩膜镜具有广泛的适应症,能有效减轻疼痛和刺激、维持眼表湿润、促进角膜上皮修复、并延长药物作用时间。这些特性使其在治疗圆锥角膜、干眼症、角膜移植后散光、屈光不正、角膜退化或营养不良以及角膜外伤等眼表疾病方面展示出显著的临床疗效,解决了传统RGP难以克服的问题。本文主要对巩膜镜在眼表疾病治疗中的治疗原理、有效性、安全性以及临床治疗中的优势与局限进行了详细总结,旨在更全面地发挥其在临床上的治疗价值。展开更多
文摘Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retinopathy has traditionally been considered as damage to the retinal microvasculature.However,growing evidence suggests that diabetic retinopathy is a complex neurovascular disorder resulting from dysfunction of the neurovascular unit,which includes both the retinal vascular structures and neural tissues.Diabetic retinopathy is one of the leading causes of blindness and is frequently screened for as part of diabetic ocular screening.However,diabetic corneal neuropathy is commonly overlooked and underdiagnosed,leading to severe ocular surface impairment.Several studies have found that these two conditions tend to occur together,and they share similarities in their pathogenesis pathways,being triggered by a status of chronic hyperglycemia.This review aims to discuss the interconnection between diabetic corneal neuropathy and diabetic retinopathy,whether diabetic corneal neuropathy precedes diabetic retinopathy,as well as the relation between the stage of diabetic retinopathy and the severity of corneal neuropathy.We also endeavor to explore the relevance of a corneal screening in diabetic eyes and the possibility of using corneal nerve measurements to monitor the progression of diabetic retinopathy.
文摘The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal limbus between cornea and scleral,are believed to be crucial for the continuous turnover of the corneal epithelium.The proliferation,migration,and differentiation of the LESCs are modulated by unique physical and chemical futures contained within the microenvironment known as the limbal niche.This niche,composed of nerve terminals,cells,extracellular matrix,vasculature,and signaling molecules,is the home for processes such as proliferation,migration and differentiation.Corneal nerve terminals possess special anatomical structures in the limbal region and basal epithelial cells,and they demonstrate pivotal biological effects in the regulation of the LESC function and corneal epithelium homeostasis.Biological molecules such as neuropeptides,neurotransmitters,and neurotrophic factors play a crucial role in modulating the LESCs phenotype responsible for corneal epithelium homeostasis.This paper will review recent studies on how these nerve derived molecules function in this process and provide clear orientations for future research.
文摘Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to assess the effect of the widely used fluorescein dye on human corneal endothelial cells(HCEnCs)in vitro at different concentrations and exposure times.Methods:B4G12,an immortalized human corneal endothelium cell line was cultured on pre-coated tissue culture flask with human endothelial-serum free medium(SFM)supplemented with 10 ng/mL basic fibroblast growth factor(bFGF).The fully confluent B4G12 cell monolayers in 96 well plates were treated with water as control,or fluorescein at various concentrations and exposure times.Cell viability was assessed using two techniques:Alamar Blue assay and cell morphology assessment with an inverted phase-contrast microscopy.Results:Short-term exposure to fluorescein(0.01-0.2%)for up to 30 minutes did not affect cell viability.Continuous fluorescein exposure however significantly reduced the viability of the cells with a notable reduction in cell metabolic activity with fluorescein treatments of 0.001%,0.01% and 0.05% for 1 day(and up to 4 days).Conclusions:Short-term exposure to fluorescein for up to 30 minutes in concentrations commonly used in clinical practice did not affect HCEnC viability.However,fluorescein exposure for longer durations can be detrimental to corneal endothelial cell health.Future studies should evaluate the effects of longer-term fluorescein exposure on endothelial function especially in susceptible patients including the elderly and patients with epithelial defects that enable diffusion of fluorescein towards the endothelium.
文摘AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospective study was designed to evaluate 82 eyes from 82 patients,all of whom had a pre-planned RST of 280 to 300μm and normal corneal topography prior to undergoing SMILE surgery.The mean preoperative spherical equivalent(SE)was-4.82±1.30 D.A standard follow-up protocol was conducted between 1 to 6mo postoperatively.Visual outcomes were recorded using uncorrected visual acuity(UCVA)and subjective refraction.The curvature of the anterior and posterior corneal surfaces,as well as the posterior elevation at the thinnest point(PTE)were derived from the Pentacam system.RESULTS:At the final follow-up,the efficacy index was 1.14±0.15,the safety index was 1.20±0.13.The mean preoperative UDVA was 0.78±0.16 logMAR,which improved significantly to-0.07±0.06 logMAR postoperatively(P<0.001).The preoperative mean SE was-4.82±1.30 D,which decreased to-0.14±0.30 D by the last visit.The curvature of the anterior cornea at the flat meridian(AK1)were 42.62±1.02 D preoperatively,38.56±1.37 D and 38.59±1.39 D at 1 and 6mo after operation,respectively.Corresponding measurements at the steep meridian(AK2)were 43.55±1.14 D preoperatively,39.18±1.46 D and 39.22±1.50 D at 1 and 6mo after operation,respectively.Both AK1 and AK2 remained stable at 1 and 6-mo postoperative intervals(P=0.126 and 0.082,respectively).There were no observed changes in the curvature of the posterior cornea at the flat meridian or at the steep meridian,or the PTE before and after surgery.CONCLUSION:SMILE represents a safe and effective procedure for the correction of myopia and astigmatism in eyes featuring a pre-planned RST ranging from 280 to 300μm accompanied by normal corneal topography,on the premise of strict control of surgical indications.
文摘AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retrospective study was conducted on 30 phakic eyes from patients diagnosed with FECD but without clinical edema,and 59 phakic eyes from a control group without corneal alterations.Comprehensive ophthalmic examinations were conducted,including slitlamp biomicroscopy,corneal specular microscopy(CSM),and Scheimpflug tomography.RESULTS:The study encompassed 30 phakic eyes with FECD(mean age 59.8±13.1y)and 59 control eyes(mean age 61.3±7.7y).The best-corrected visual acuity was higher in the control group compared to the FECD group[0(0,0.08)vs 0.05(0,0.15)logMAR;P=0.042].CSM revealed significant differences between the FECD and control groups in several parameters:number of analyzed cells(26±13 vs 135±42,P<0.001),cell density(2049±376 vs 2479±225 cells/mm2,P<0.001),mean cell area[463(434,544)vs 397(383,431)μm2;P<0.001],coefficient of variation(54.8%±18.7%vs 41.0%±7.2%,P<0.001),and hexagonal cells[0(0,47%)vs 47%(40%,53%),P<0.001].Although often used as a clinical parameter for detecting edema,central corneal thickness measured by CSM showed no significant difference between the FECD and control groups(530±57 vs 546±30μm,P=0.179).Significant differences were noted in various Pentacam measurements between the groups.Specifically,parameters like loss of parallel isopachs(13 vs 0 eyes,P<0.001),displacement of the thinnest point(11 vs 0 eyes,P<0.001),posterior focal depression(25 vs 7 eyes,P<0.001),and increased light scatter[21.4(17.6;23.9)vs 18.0(16.8,21.8),P=0.01]were significantly more prevalent in FECD eyes,reflecting the presence of subclinical edema and loss of corneal transparency.CONCLUSION:Scheimpflug tomography allows for an objective assessment of FECD,offering the capability to detect subclinical edema at an early stage,monitor disease progression,and serve as a predictor of corneal decompensation following cataract surgery.
文摘AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective study included patients with thin corneas(preoperative thinnest corneal thickness ranging from 480 to 520μm)who underwent SMILE for myopia or myopic astigmatism.Corneal topography and posterior corneal elevation were assessed using Pentacam HR at three time points:preoperatively,1mo,and 6mo postoperatively.The measured parameters included thinnest point elevation(PTE),posterior maximal elevation(PME),posterior central elevation(PCE),and 24 additional reference points.RESULTS:A total of 106 eyes from 106 patients(age range:18-34)were included in the study.Uncorrected distance visual acuity(UDVA)improved significantly,with a mean logMAR value of-0.07±0.06 at the final follow-up visit.Measurements of posterior corneal elevation showed no significant changes in most points,hemispheres,and meridians at 6mo postoperatively.Notably,only two points,ΔE_(2mm-45°)andΔE_(2mm-90°),exhibited statistically significant elevation changes:the elevation ofΔE_(2mm-45°)increased from-2.3±4.99 to-1.0±5.9μm(P=0.0037),and that ofΔE_(2mm-90°)increased from-16±7.53 to-15±7.4μm(P=0.016).However,these changes were within the measurement error range of the Pentacam HR(±5μm in a 5 mm area).CONCLUSION:SMILE surgery is a safe and stable procedure for correcting myopia or myopic astigmatism in patients with thin corneas,as evidenced by the stability of posterior corneal elevation.
文摘Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.
文摘巩膜接触镜通常称为巩膜镜,是一种新型的大直径高透氧性硬性眼表接触镜,能够覆盖角膜、角膜缘及部分巩膜。与传统的角膜接触镜(rigid gas permeable,RGP)相比,巩膜镜具有广泛的适应症,能有效减轻疼痛和刺激、维持眼表湿润、促进角膜上皮修复、并延长药物作用时间。这些特性使其在治疗圆锥角膜、干眼症、角膜移植后散光、屈光不正、角膜退化或营养不良以及角膜外伤等眼表疾病方面展示出显著的临床疗效,解决了传统RGP难以克服的问题。本文主要对巩膜镜在眼表疾病治疗中的治疗原理、有效性、安全性以及临床治疗中的优势与局限进行了详细总结,旨在更全面地发挥其在临床上的治疗价值。
