Changes in corneal high-order aberrations and their influencing factors in early stages following orthokeratology contact lens wear / 中华实验眼科杂志

Objective To evaluate changes in corneal high-order aberrations after the wearing of orthokeratology contact lenses and to study the factors influencing those changes.Methods A series of case-observational method was used.Data on 46 right myopic eyes of 46 children fitted for orthokeratology were continuously collected from January to April 2018.The corneal morphology,the e values of the anterior and posterior corneal surface in the nasal,temporal,superior and inferior zones within 6 mm were measured with Pentacam Anterion Segment Analysis System before and one month after the wearing of orthokeratology contact lens.Zernike Analysis System was used to calculate the values of Z33,Z3-3,Z31,Z3-1,and Z40 on the anterior and posterior surfaces and on the total cornea within a diameter of 6 mm.This study conformed to the tenets of the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baoding Yinghua Eye Hospital (No.YKLL-2018-1-01).Written informed consent was obtained from each child and their guardians prior to entering the study cohort.Results Compared to the values recorded prior to orthokeratology contact lens wear,the horizontal coma,vertical coma,and spherical aberration of the total cornea and anterior corneal surface were drifted positively after lens wear;the horizontal coma and spherical aberration of the posterior corneal surface were drifted negatively after lens wear;and the differences were statistically significant (all at P＜0.05).Before wearing orthokeratology contact lenses,eNf,eTf,eIf,eSf and eMf values were 0.580(0.450,0.670),0.455 (0.378,0.513),0.485 (0.268,0.553),0.665(0.578,0.740) and 0.505±0.015,respectively,and after wearing orthokeratology contact lenses,eNf,eTf,eIr,eSf and eMf values were 0.285(-0.635,0.665),-0.605 (-0.813,-0.335),-0.545 (-0.765,0.305),-0.335 (-0.705,0.423) and -0.247±0.058,respectively.Compared with the conditions prior to wearing orthokeratology contact lens,the anterior corneal surface in all parts changed from steep to fiat after lens wear,with statistically significant differences between them (all at P＜0.05).The results of multiple stepwise linear regression showed that after wearing orthokeratology contact lens,the spherical aberration of the total cornea was moderately negatively correlated with the corneal e value and the initial diopter (rs =-0.626,-0.450;both at P＜0.05),the horizontal coma of the total cornea was moderately negatively correlated with the temporal e value (rs =-0.391,P =0.004);the spherical aberration of the anterior corneal surface was moderately negatively correlated with the corneal e value and the initial diopter (rs =-0.612,-0.432;both at P＜0.05);the horizontal coma of the anterior corneal surface was moderately negatively correlated with the temporal e value (rs =-0.400,P =0.003);and the horizontal coma of the posterior corneal surface was negatively correlated with the horizontal coma of the anterior corneal surface (rs =-0.380,P =0.009).Conclusions The spherical aberration and coma of the total cornea and anterior corneal surface drift positively after wearing orthokeratology contact lens,and the spherical aberration and horizontal coma of the posterior corneal surface drift negatively.The refraction and deformation of the anterior surface of the cornea are important factors affecting variation in corneal high-order aberrations.

Changes in corneal high-order aberrations and their influencing factors in early stages following orthokeratology contact lens wear / 中华实验眼科杂志

Objective@#To evaluate changes in corneal high-order aberrations after the wearing of orthokeratology contact lenses and to study the factors influencing those changes.@*Methods@#A series of case-observational method was used.Data on 46 right myopic eyes of 46 children fitted for orthokeratology were continuously collected from January to April 2018.The corneal morphology, the e values of the anterior and posterior corneal surface in the nasal, temporal, superior and inferior zones within 6 mm were measured with Pentacam Anterion Segment Analysis System before and one month after the wearing of orthokeratology contact lens.Zernike Analysis System was used to calculate the values of Z33, Z3-3, Z31, Z3-1, and Z40 on the anterior and posterior surfaces and on the total cornea within a diameter of 6 mm.This study conformed to the tenets of the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Baoding Yinghua Eye Hospital (No.YKLL-2018-1-01). Written informed consent was obtained from each child and their guardians prior to entering the study cohort.@*Results@#Compared to the values recorded prior to orthokeratology contact lens wear, the horizontal coma, vertical coma, and spherical aberration of the total cornea and anterior corneal surface were drifted positively after lens wear; the horizontal coma and spherical aberration of the posterior corneal surface were drifted negatively after lens wear; and the differences were statistically significant (all at P<0.05). Before wearing orthokeratology contact lenses, eNf, eTf, eIf, eSf and eMf values were 0.580(0.450, 0.670), 0.455(0.378, 0.513), 0.485(0.268, 0.553), 0.665(0.578, 0.740) and 0.505±0.015, respectively, and after wearing orthokeratology contact lenses, eNf, eTf, eIf, eSf and eMf values were 0.285(-0.635, 0.665), -0.605(-0.813, -0.335), -0.545(-0.765, 0.305), -0.335(-0.705, 0.423) and -0.247±0.058, respectively.Compared with the conditions prior to wearing orthokeratology contact lens, the anterior corneal surface in all parts changed from steep to flat after lens wear, with statistically significant differences between them (all at P<0.05). The results of multiple stepwise linear regression showed that after wearing orthokeratology contact lens, the spherical aberration of the total cornea was moderately negatively correlated with the corneal e value and the initial diopter (rs=-0.626, -0.450; both at P<0.05), the horizontal coma of the total cornea was moderately negatively correlated with the temporal e value (rs=-0.391, P=0.004); the spherical aberration of the anterior corneal surface was moderately negatively correlated with the corneal e value and the initial diopter (rs=-0.612, -0.432; both at P<0.05); the horizontal coma of the anterior corneal surface was moderately negatively correlated with the temporal e value (rs=-0.400, P=0.003); and the horizontal coma of the posterior corneal surface was negatively correlated with the horizontal coma of the anterior corneal surface (rs=-0.380, P=0.009).@*Conclusions@#The spherical aberration and coma of the total cornea and anterior corneal surface drift positively after wearing orthokeratology contact lens, and the spherical aberration and horizontal coma of the posterior corneal surface drift negatively.The refraction and deformation of the anterior surface of the cornea are important factors affecting variation in corneal high-order aberrations.

Contrast to wavefront optimized and wavefront guided excimer laser photorefractive keratectomy / 中华实验眼科杂志

Conventional excimer laser keratectomy have been proved to achieve better visual function,but the traditional therapy of corneal spherical cutting line generally flat profile will make the cornea more oblate shape and the contours of the cornea and lcad to spherical aberration.The alteration of non.spherical nature cause the increase of corneal spherical aberration,which further affects the night vision and contrast sensitivity and other visual quality.Wavefront optimization based on total number of adjustments are to retain the previous visual aberrations of eyes and optimize the non-spherical nature of cornea to create a ideal model based on individual adjustments.Ocular wavefront-guided measurement and ablation in exeimer laser keratectomy can achieve better visual outcome.In this paper,wavefront guided and wavefront optimized treatment outcome for the spherical aberration correction are reviewed.

The Relationship Between Asphericity and Visual Acuity After Wearing Reverse-Geometry Lens

PURPOSE:To report the change of corneal asphericity and the relationship between asphericity and visual acuity after wearing the reverse-geometry lens. METHODS: The authors reviewed out-patient records of 37 consecutive patients wearing reverse-geometry lenses. The patients were followed up from July 2004 to December 2007. The unaided visual acuity (VA), spherical equivalent (SE) and asphericity before and after wearing the lens were compared. The relationship of SE and final VA, initial astigmatism and final VA, and asphericity and final VA was also analyzed. In addition, the relationship between the increment of VA and asphericity was determined. RESULTS: VA and SE improved and the asphericity decreased after wearing the lens (p<0.05). There was high correlation between the spherical equivalent and final visual acuity (p<0.001), and no correlation between asphericity and final visual acuity (p=0.358) was observed. However, the lower the initial asphericity, the greater the increment of visual acuity observed (p=0.048). CONCLUSIONS: Initial corneal asphericity can be a predictor of increment of VA after wearing reverse-geometry lenses.