Assessment Of Visual Quality With Mild And Moderate Keratoconus Based On Optical Quality Analysis System ? Parameters

Part 1 Assessment of visual quality in eyes with forme fruste keratoconus,mild and moderate keratoconus based on optical quality analysis system ? parametersPurpose.The study aimed to evaluate the visual quality of forme fruste keratoconus(FFK),mild and moderate keratoconus by using optical quality analysis system ?(OQAS-?)and to explore the correlation between optical quality parameters and the disease progression.Methods,Twenty-one normal eyes,twenty-one FFK eyes,twenty-one mild keratoconus eyes and twenty-one moderate keratoconus eyes were included in this prospective study.The optical quality parameters,such as object scatter index(OSI),modulation transfer function cut off(MTF cut off),strehl ratio(SR),OQAS-? values at contrasts of 100%(OV-100),20%(OV-20),9%(OV-9),were measured by OQAS-?.The repeatability of these parameters was analyzed by intraclass correlation coefficient(ICC),repeatability coefficient(RC)and coefficient of variation(CVw).Correlations between optical quality parameters and mean central keratometry readings(Krean)were evaluated.The sensitivity and specificity of the parameters were analyzed using the receiver operating characteristic(ROC).Results.All the optical quality parameters among four groups showed good repeatability(all ICC?0.75).The MTF cut off,SR,OV-100,OV-20,OV-9 in FFK,mild and moderate keratoconus eyes were significantly lower than those in normal group(all P<0.05).The ROC analyses of the MTF cut off,SR,OV-100,OV-20,OV-9 showed significant area under the curve(AUC)in discriminating FFK form normal,mild keratoconus from FFK,and moderate keratoconus from mild keratoconus(all P<0.05).The OSI in mild and moderate keratoconus eyes were significantly higher than that in FFK and normal group(all P<0.05),while the OSI showed no significant difference between the FFK group and normal group(P>0.05).The ROC analyses of the OSI showed significant AUC in discriminating mild keratoconus from FFK,and moderate keratoconus from mild keratoconus(all P<0.05).In addition,the MTF cut off was closely correlated to Kmean in keratoconus eyes(r=-0.710,P<0.001).Conclusion.The repeatability of OQAS-? is good in measuring visual quality of normal as well as FFK,mild,and moderate keratoconus.The visual quality of the FFK,mild and moderate keratoconus is worse than that in normal eyes.The OQAS-? has the potential value in screening FFK from normal eyes and might be a useful tool for evaluating the progression of keratoconus.Part 2 Assessment of the influence of rigid gas-permeable contact lenses in mild and moderate keratoconus based on optical quality analysis system ?Purpose.To evaluate the influence of rigid gas permeable contact lens(RGPCL)in mild and moderate keratoconus based on OQAS-?.Methods Twenty-five eyes of twenty mild and moderate keratoconus patients whose best corrected visual acuity were over 0.6 were recruited in Henan Province People's Hospital from December 2018 to June 2019.The diagnosis and staging of mild and moderate keratoconus were based on Global Consensus on Keratoconus and Keratoconus Severity Score Ranking Scheme(KSS).The patients were analysed by OQAS-? before and one month after wearing RGPCL respectively,including the value of OSI,MTF cut off,SR,OV-100,OV-20,OV-9,and tear film objective scatter index(TF-OSI).Person product moment coefficient was used to evaluate the correlation between the optical quality parameters and Ks.Results The OSI,MTF cut off,SR,OV-100,OV-20,OV-9 and TF-OSI before wearing RGPCL were 4.07±4.73,23.58±15.66(c/d),0.15±0.09,0.79±0.52,0.56±0.41,0.36±0.27,0.68±0.79 respectively.The OSI,MTF cut off,SR,OV-100,OV-20,OV-9 and TF-OSI one month after wearing RGPCL were 1.30±1.08,32.71±11.55(c/d),0.20±0.07,1.10±0.39,0.79±0.31,0.50±0.20,0.61±0.77 respectively.The OSI decreased significantly and the MTF cut off,SR,OV-100,OV-20 and OV-9 increased significantly one month after wearing RGPCL(all P<0.05),while the TF-OSI showed no statistical difference one month after wearing RGPCL(P>0.05).There was significant negative correlation between MTF cut off and Ks before wearing RGPCL(r=-0.502,P<0.05),but there was no significant correlation between MTF cut off and Ks one month after wearing RGPCL(P>0.05).Conclusion RGPCL could improve the visual quality in mild and moderate keratoconus,but the long-term outcome should be further investigated.