AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with hig...AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with high myopia(-6.00 to-8.75 D)with(up to-3.00 D)or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran.One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser.One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront(OWF)and corneal wave-front(CWF)higher order aberrations(HOA),contrast sensitivity(CS),and postoperative haze were assessed.RESULTS:After the surgery,both photopic and mesopic CSs significantly improved(both P〈0.001).We detected significant induction of OWF coma and trefoil(P〈0.001 for both)HOAs;CWF coma(P=0.002),spherical(P〈0.001),and tetrafoil(P=0.003)HOAs in 6 mm analysis diameter;and CWF trefoil(P=0.04)HOA in 4 mm analysis diameter.The range of mean induction observed for various HOAs was0.005-0.11μm.The 86.7%of eyes reached an uncorrected distance visual acuity of 20/20 or better;96.7%of eyes were within±0.5 D of targeted spherical refraction.In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22.By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines.We detected no corneal haze greater than 1~+throughout the follow-up.CONCLUSION:Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes.It also improves refraction and visual acuity.展开更多
The human eye is an asymmetric optical system and the real cornea is not a rotationally symmetrical volume.Each optical element in the eye has its own optical and neural axes.Defining the optimum center for laser abla...The human eye is an asymmetric optical system and the real cornea is not a rotationally symmetrical volume.Each optical element in the eye has its own optical and neural axes.Defining the optimum center for laser ablation is difficult with many available approaches.We explain the various centration approaches(based on these reference axes)in refractive surgery and review their clinical outcomes.The line-of-sight(LOS)(the line joining the entrance pupil center with the fixation point)is often the recommended reference axis for representing wavefront aberrations of the whole eye(derived from the definition of chief ray in geometrical optics);however pupil centration can be unstable and change with the pupil size.The corneal vertex(CV)represents a stable preferable morphologic reference which is the best approximate for alignment to the visual axis.However,the corneal light reflex can be considered as non-constant,but dependent on the direction of gaze of the eye with respect to the light source.A compromise between the pupil and CV centered ablations is seen in the form of an asymmetric offset where the manifest refraction is referenced to the CV while the higher order aberrations are referenced to the pupil center.There is a need for a flexible choice of centration in excimer laser systems to design customized and non-customized treatments optimally.展开更多
Purpose:The aim of this systematic review was to synthesize and appraise the evidence of the benefits of presbyopic correction on the cornea for visual function.Summary:Comprehensive search was conducted in MEDLINE us...Purpose:The aim of this systematic review was to synthesize and appraise the evidence of the benefits of presbyopic correction on the cornea for visual function.Summary:Comprehensive search was conducted in MEDLINE using keywords like“presbylasik”,“presbyopic refractive surgery”,“corneal pseudoaccommodation”and“corneal multifocality”.We reviewed corrected and uncorrected visual acuities for distance and near(uncorrected distance visual acuity(UDVA),uncorrected near visual acuity(UNVA),corrected distance visual acuity(CDVA),distance corrected near visual acuity(DCNVA),corrected near visual acuity(CNVA)),along with the refractive outcomes in spherical equivalent(SE)and astigmatism comparing the differences observed between preoperative myopic and hyperopic patients,as well as among techniques.Thirty-one studies met the inclusion and quality criteria.Monovision provides excellent distance and near uncorrected acuities,but with a 17%retreatment and a 5%reversal rate.Initial multifocal ablations result in 12%loss of 2 or more lines of CDVA,and a 21%retreatment rate.Laser Blended Vision provides excellent UDVA,but with a 19%retreatment rate.Initial experiences with Supracor show moderate predictability and a 22%retreatment rate.Intracor results in 9%loss of 2 or more lines of CDVA.KAMRA provides excellent UDVA,with only a 1%retreatment rate,but a 6%reversal rate.Initial experiences with PresbyMAX provided excellent UNVA and DCNVA,showing excellent predictability and a 1%reversal rate.Conclusions:The findings have implications for clinicians and policymakers in the health-care industry and emphasize the need for additional trials examining this important and widely performed clinical procedure.展开更多
Background:To retrospectively analyse strategies for adjusting refractive surgery plans with reference to the preoperative manifest refraction.Methods:We constructed seven nomograms based on the refractive outcomes(sp...Background:To retrospectively analyse strategies for adjusting refractive surgery plans with reference to the preoperative manifest refraction.Methods:We constructed seven nomograms based on the refractive outcomes(sphere,cylinder,axis[SCA])of 150 consecutive eyes treated with laser in situ keratomileusis for myopic astigmatism.We limited the initial data to the SCA of the manifest refraction.All nomograms were based on the strategy:if for x diopters(D)of attempted metric,y D is achieved;we can reverse this sentence and state for achieving y D of change in the metric,x D will be planned.The effects of the use of plus or minus astigmatism notation,spherical equivalent,sphere,principal meridians notation,cardinal and oblique astigmatism,and astigmatic axis were incorporated.Results:All nomograms detected subtle differences in the spherical component(p<0.0001).Nomograms 5 and 7(using power vectors)and 6(considering axis shifts)detected significant astigmatic differences(nomogram 5,p<0.001;nomogram 6,p<0.05;nomogram 7,p<0.005 for cardinal astigmatism,p=0.1 for oblique astigmatism).We observed mild clinically relevant differences(~0.5 D)in sphere or astigmatism among the nomograms;differences of~0.25 D in the proposals for sphere or cylinder were not uncommon.All nomograms suggested minor improvements versus actual observed outcomes,with no clinically relevant differences among them.Conclusions:All nomograms anticipated minor improvements versus actual observed outcomes without clinically relevant differences among them.The minimal uncertainties in determining the manifest refraction(~0.6 D)are the major limitation to improving the accuracy of refractive surgery nomograms.展开更多
Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven nor...Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven normal subjects(with no ocular pathology)who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen(Germany).In all cases,standard examinations and corneal wavefront topography(OPTIKON Scout)were performed.The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations,and FOZ-values were evaluated from the Root-Mean-Square(RMS)of High-Order Wavefront-Aberration(HOWAb).Moreover,correlations of FOZ,spherical equivalent(SE),astigmatism power,and cardinal and oblique astigmatism for binocular vs.monocular,and binocular vs.intercorneal differences were analyzed.Results:Mean FOZ was 6.56±1.13 mm monocularly,6.97±1.34 mm binocularly,and 7.64±1.30 mm intercorneal difference,with all strongly positively correlated,showing that the diameter of glare-free vision is larger in binocular than monocular conditions.Mean SE was 0.78±1.30 D,and the mean astigmatism power(magnitude)was 0.46±0.52 D binocularly.The corresponding monocular values for these metrics were 0.78±1.30 D and 0.53±0.53 D respectively.SE,astigmatism magnitude,cardinal astigmatism component,and FOZ showed a strong correlation and even symmetry;and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.Conclusions:These results confirm OD-vs.-OS bilateral symmetry(which influences binocular summation)of HOWAb,FOZ,defocus,astigmatism power,and cardinal and oblique astigmatism.Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.展开更多
文摘AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with high myopia(-6.00 to-8.75 D)with(up to-3.00 D)or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran.One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser.One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront(OWF)and corneal wave-front(CWF)higher order aberrations(HOA),contrast sensitivity(CS),and postoperative haze were assessed.RESULTS:After the surgery,both photopic and mesopic CSs significantly improved(both P〈0.001).We detected significant induction of OWF coma and trefoil(P〈0.001 for both)HOAs;CWF coma(P=0.002),spherical(P〈0.001),and tetrafoil(P=0.003)HOAs in 6 mm analysis diameter;and CWF trefoil(P=0.04)HOA in 4 mm analysis diameter.The range of mean induction observed for various HOAs was0.005-0.11μm.The 86.7%of eyes reached an uncorrected distance visual acuity of 20/20 or better;96.7%of eyes were within±0.5 D of targeted spherical refraction.In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22.By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines.We detected no corneal haze greater than 1~+throughout the follow-up.CONCLUSION:Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes.It also improves refraction and visual acuity.
文摘The human eye is an asymmetric optical system and the real cornea is not a rotationally symmetrical volume.Each optical element in the eye has its own optical and neural axes.Defining the optimum center for laser ablation is difficult with many available approaches.We explain the various centration approaches(based on these reference axes)in refractive surgery and review their clinical outcomes.The line-of-sight(LOS)(the line joining the entrance pupil center with the fixation point)is often the recommended reference axis for representing wavefront aberrations of the whole eye(derived from the definition of chief ray in geometrical optics);however pupil centration can be unstable and change with the pupil size.The corneal vertex(CV)represents a stable preferable morphologic reference which is the best approximate for alignment to the visual axis.However,the corneal light reflex can be considered as non-constant,but dependent on the direction of gaze of the eye with respect to the light source.A compromise between the pupil and CV centered ablations is seen in the form of an asymmetric offset where the manifest refraction is referenced to the CV while the higher order aberrations are referenced to the pupil center.There is a need for a flexible choice of centration in excimer laser systems to design customized and non-customized treatments optimally.
文摘Purpose:The aim of this systematic review was to synthesize and appraise the evidence of the benefits of presbyopic correction on the cornea for visual function.Summary:Comprehensive search was conducted in MEDLINE using keywords like“presbylasik”,“presbyopic refractive surgery”,“corneal pseudoaccommodation”and“corneal multifocality”.We reviewed corrected and uncorrected visual acuities for distance and near(uncorrected distance visual acuity(UDVA),uncorrected near visual acuity(UNVA),corrected distance visual acuity(CDVA),distance corrected near visual acuity(DCNVA),corrected near visual acuity(CNVA)),along with the refractive outcomes in spherical equivalent(SE)and astigmatism comparing the differences observed between preoperative myopic and hyperopic patients,as well as among techniques.Thirty-one studies met the inclusion and quality criteria.Monovision provides excellent distance and near uncorrected acuities,but with a 17%retreatment and a 5%reversal rate.Initial multifocal ablations result in 12%loss of 2 or more lines of CDVA,and a 21%retreatment rate.Laser Blended Vision provides excellent UDVA,but with a 19%retreatment rate.Initial experiences with Supracor show moderate predictability and a 22%retreatment rate.Intracor results in 9%loss of 2 or more lines of CDVA.KAMRA provides excellent UDVA,with only a 1%retreatment rate,but a 6%reversal rate.Initial experiences with PresbyMAX provided excellent UNVA and DCNVA,showing excellent predictability and a 1%reversal rate.Conclusions:The findings have implications for clinicians and policymakers in the health-care industry and emphasize the need for additional trials examining this important and widely performed clinical procedure.
文摘Background:To retrospectively analyse strategies for adjusting refractive surgery plans with reference to the preoperative manifest refraction.Methods:We constructed seven nomograms based on the refractive outcomes(sphere,cylinder,axis[SCA])of 150 consecutive eyes treated with laser in situ keratomileusis for myopic astigmatism.We limited the initial data to the SCA of the manifest refraction.All nomograms were based on the strategy:if for x diopters(D)of attempted metric,y D is achieved;we can reverse this sentence and state for achieving y D of change in the metric,x D will be planned.The effects of the use of plus or minus astigmatism notation,spherical equivalent,sphere,principal meridians notation,cardinal and oblique astigmatism,and astigmatic axis were incorporated.Results:All nomograms detected subtle differences in the spherical component(p<0.0001).Nomograms 5 and 7(using power vectors)and 6(considering axis shifts)detected significant astigmatic differences(nomogram 5,p<0.001;nomogram 6,p<0.05;nomogram 7,p<0.005 for cardinal astigmatism,p=0.1 for oblique astigmatism).We observed mild clinically relevant differences(~0.5 D)in sphere or astigmatism among the nomograms;differences of~0.25 D in the proposals for sphere or cylinder were not uncommon.All nomograms suggested minor improvements versus actual observed outcomes,with no clinically relevant differences among them.Conclusions:All nomograms anticipated minor improvements versus actual observed outcomes without clinically relevant differences among them.The minimal uncertainties in determining the manifest refraction(~0.6 D)are the major limitation to improving the accuracy of refractive surgery nomograms.
文摘Background:In this retrospective randomized case series,we compared bilateral symmetry between OD and OS eyes,intercorneal differences and Functional Optical Zone(FOZ)of the corneal aberrations.Methods:Sixty-seven normal subjects(with no ocular pathology)who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen(Germany).In all cases,standard examinations and corneal wavefront topography(OPTIKON Scout)were performed.The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations,and FOZ-values were evaluated from the Root-Mean-Square(RMS)of High-Order Wavefront-Aberration(HOWAb).Moreover,correlations of FOZ,spherical equivalent(SE),astigmatism power,and cardinal and oblique astigmatism for binocular vs.monocular,and binocular vs.intercorneal differences were analyzed.Results:Mean FOZ was 6.56±1.13 mm monocularly,6.97±1.34 mm binocularly,and 7.64±1.30 mm intercorneal difference,with all strongly positively correlated,showing that the diameter of glare-free vision is larger in binocular than monocular conditions.Mean SE was 0.78±1.30 D,and the mean astigmatism power(magnitude)was 0.46±0.52 D binocularly.The corresponding monocular values for these metrics were 0.78±1.30 D and 0.53±0.53 D respectively.SE,astigmatism magnitude,cardinal astigmatism component,and FOZ showed a strong correlation and even symmetry;and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye.Conclusions:These results confirm OD-vs.-OS bilateral symmetry(which influences binocular summation)of HOWAb,FOZ,defocus,astigmatism power,and cardinal and oblique astigmatism.Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.
