The Effect Of Astigmatism Axis On Optical Quality In Moderate To Low Degree Astigmatism Eye

Part Ⅰ The influence of with the rule astigmatism,oblique astigmatism and against the rule astigmatism on optical quality in moderate to low degree astigmatism eyeObjective:To evaluate the effect of astigmatism degree and axis on objective optical quality by using dual channel optical quality analysis system,so as to provide basis for clinical correction of moderate and low astigmatism.Methods:A cross-sectional self-control study was conducted in healthy young people aged 18-30 who underwent routine eye examination in the ophthalmic clinic of Affiliated Hospital of North Sichuan Medical College from January to October 2020.The measured values of the right eye were taken.After correcting the original ametropia,the astigmatism with different diopters and axial direction were induced by lens.According to the diopter,they were divided into three groups,-1.00DC group,-1.50DC group and-2.00DC group.The same diopter was divided into three subgroups according to the axial difference of astigmatism,with the rule astigmatism(WTR)group(axial 180),oblique astigmatism(OBL)group(axial 45),against the rule astigmatism(ATR)group(axial 90),namely-1.0ODC×180,-1.00DC×45,-1.00DC×90;-1.50DC×180,-1.50DC×45,-1.50DC×90;-2.00DC×180,-2.00DC×45,-2.00DC×90.Used the standard logarithmic distance chart to test the best corrected visual acuity(BCVA)before induced astigmatism and the uncorrected visual acuity(UCVA)after induced astigmatism,and used the objective optical quality analysis system(OQAS)to examine the visual quality of subjects before and after induced astigmatism.The analysis parameters included objective scatter index(OSI),modulation transfer function cutoff frequency(MTF cutoff),Strehl ratio(SR)and predicted visual acuity(Predicted VA)under three contrast ratios,VA100%,VA20%,VA9%.Repeated measures analysis of variance was used to compare the differences of each parameter between the groups and the Bonfferoni method was used for pairwise comparison.Result:After correcting the original refractive error,BCVA was(-0.011±00.030)LogMAR,OSI was 0.505±0.292,MTF cutoff was(43.082±6.483)c/deg,SR was 0.234±0.050,VA100%,VA20%and VA9%was 1.432±0.222,1.059±0.228 and 0.636±0.159,respectively.In-1.00 DC group,the visual acuity of WTR group,OBL group and ATR group was(0.102±0.100)LogMAR,(0.164±0.116)LogMAR,(0.127±0.119)LogMAR,respectively;OSI were 0.878±0.499,0.954±0.570,0.986±0.503;MTF cutoff was(30.740±7.703)c/deg,(30.068±8.222)c/deg,(29.667±7.261)c/deg;SR was 0.175±0.041,0.171±0.041,0.169±0.037;VA100%was 1.037±0.263,1.004±0.256,1.003±0.240;VA20%was 0.7161±0.208,0.685±0.186,0.674±0.194;VA9%was 0.435±0.124,0.414±0.113 and 0.409±0.116.In-1.50DC group,the visual acuity of WTR group,OBL group and ATR group was(0.209±0.106)LogMAR,(0.326±0.135)LogMAR,(0.235±0.123)LogMAR,respectively;OSI was 1.228±0.772,1.266±0.727,1.278±0.537;MTF cutoff was(25.644±7.201)c/deg,(24.892±6.771)c/deg,(24.479±6.038)c/deg;SR was 0.144±0.038,0.141±0.033,0.137±0.028;VA100%was 0.854±0.242,0.819±0.220,0.811±0.194;VA20%was 0.573±0.180,0.548±0.141,0.537±0.146;VA9%was 0.349±0.112,0.326±0.091,0.333±0.079.In-2.00DC group,the visual acuity of WTR group,OBL group and ATR group was(0.319±0.118)LogMAR,(0.442±0.149)LogMAR,(0.346±0.156)LogMAR,respectively;OSI was 1.516±0.809,1.609±0.914,1.611±0.822;MTF cutoff was(21.4044±6.597)c/deg,(20.741±5.754)c/deg,(21.075±5.810)c/deg;SR was 0.125±0.033,0.119±0.029,0.118±0.030;VA100%was 0.716±0.224,0.687±0.206,0.700±0.194;VA20%was 0.466±0.143,0.436±0.123,0.447±0.127;VA9%was 0.280±0.090,0.266±0.081,0.273±0.076.With the increase of astigmatism,visual acuity got worse,MTF cutoff,SR,VA100%,VA20%,VA9%values gradually decreased,OSI value gradually increased,and the differences were statistically significant(all P<0.05).Under the same astigmatism diopter,the visual acuity of the WTR group and the ATR group was equivalent(P>0.05),and both were better than the OBL group(both P<0.05).In-1.00DC group,the OSI of ATR group,OBL group,and WTR group decreased in turn,the differences were statistically significant(all P<0.05).While in-1.50DC group and-2.00DC group,there were no statistically significant differences in OSI between the WTR group,OBL group and ATR group under the same astigmatism diopter(all P>0.05).In-1.00DC group,-1.50DC group and-2.00DC group,there were no significant differences in the other visual quality parameter values of the WTR group,OBL group and ATR group under the same astigmatism diopter(all P>0.05).Conclusion:The visual acuity and optical quality decreased with the increase of astigmatism.Clinical attention should be paid to the correction of-1.00DC astigmatism,especially ATR and OBL,while all astigmatism axes above-1.50DC have a great impact on visual acuity and optical quality,which should be actively corrected.Part Ⅱ Research on the difference of visual quality caused by astigmatism axial differenceObjective:To evaluate the difference of optical quality caused by astigmatism axial difference between with the rule astigmatism and against the rule astigmatism by dual channel optical quality analysis system.Methods:A cross-sectional self-control study was conducted in healthy young people aged 18-30 who underwent routine eye examination in the ophthalmic clinic of Affiliated Hospital of North Sichuan Medical College from January to October 2020.The measured values of the right eye were taken.After correcting the original ametropia,the astigmatism with different diopters and axial direction were induced by lens.According to the diopter,they were divided into three groups,-1.00DC group,-1.50DC group and-2.00DC group.The same diopter was divided into four subgroups according to the axial difference of astigmatism,15 axial groups(near 180),30 axial groups(near 45),60 axial groups(near 45),and 75 axial groups(near 90).Namely-1.00DC×15,-1.00DC×30,-1.00DC×60,-1.00DC×75;-1.50DC×15,-1.50DC×30,-1.50DC×60,-1.50DC×75;-2.00DC×15,-2.00DC×30,-2.00DC×60,-2.00DC×75.Used the standard logarithmic distance chart to test the uncorrected visual acuity(UCVA)and used the objective optical quality analysis system(OQAS)to examine the visual quality of subjects.The analysis parameters included objective scatter index(OSI),modulation transfer function cutoff frequency(MTF cutoff),Strehl ratio(SR)and predicted visual acuity(Predicted VA)under three contrast ratios,VA100%,VA20%,VA9%.Repeated measures analysis of variance was used to compare the differences of each parameter between the groups and the Bonfferoni method was used for pairwise comparison.Results:In-1.00DC group,the UCVA of the axial 15,30,60 and 75 group was(0.116±0.107)LogMAR,(0.142±0.105)LogMAR,(0.147±0.113)LogMAR,(0.129±0.115)LogMAR;OSI was 0.930±0.545,0.938±0.558,0.999±0.536,0.992±0.538;MTF cutoff was(30.352±7.636)c/deg,(30.124±7.431)c/deg,(29.316±7.478)c/deg,(29.367±7.060)c/deg;SR was 0.175±0.046,0.172±0.040,0.167±0.037,0.169±0.037;VA100%was 1.014±0.255,1.008±0.247,0.983±0.255,0.992±0.226;VA20%was 0.698±0.195,0.695±0.186,0.667±0.180,0.673±0.199;VA9%was 0.428±0.139,0.424±0.113,0.407±0.115,0.409±0.110.In-1.50DC group,the UCVA of the axial 15,30,60,and 75 group was(0.246±0.118)LogMAR,(0.293±0.119)LogMAR,(0.297±0.132)LogMAR,(0.269±0.120)LogMAR,respectively;OSI was 1.246±0.738,1.2561±0.685,1.311±0.700,1.300±0.637;MTF cutoff was(25.356±7.101)c/deg,(25.164±6.589)c/deg,(24.357±6.458)c/deg,(24.395±6.181)c/deg;SR was 0.142±0.038,0.142±0.060,0.139±0.029,0.139±0.029;VA100%was 0.840±0.239,0.809±0.201,0.806±0.215,0.809±0.211;VA20%was 0.557±0.183,0.555±0.162,0.538±0.158,0.538±0.140;VA9%was 0.340±0.118,0.335±0.103,0.324±0.089,0.324±0.085.In-2.00DC group,the UCVA of the axial 15,30,60,and 75 group was(0.343±0.117)LogMAR,(0.386±0.154)LogMAR,(0.415±0.158)LogMAR,(0.352±0.156)LogMAR,respectively;OSI was 1.549±0.861,1.569±0.839,1.629±0.858,1.628±0.787;MTF cutoff was(21.237±6.426)c/deg,(21.083±5.614)c/deg,(20.849±5.121)c/deg,(20.891±5.881)c/deg;SR was 0.125±0.038,0.124±0.030,0.119±0.026,0.119±0.027;VA100%was 0.712±0.228,0.703±0.205,0.700±0.160,0.702±0.201;VA20%was 0.451±0.137,0.441±0.122,0.444±0.121,0.446±0.129;VA9%was 0.275±0.105,0.270±0.090,0.261±0.074,0.265±0.084.With the increase of astigmatism,visual acuity got worse,MTF cutoff,SR,VA100%,VA20%,VA9%values gradually decreased,OSI value gradually increased,and the differences were statistically significant(all P<0.05).Under the same astigmatism diopter,the visual acuity of the axis close to 45 was worse,and the difference was statistically significant(P<0.05).In-1.00DC group,the OSI of the axis close to 180 was smaller than axis close to 45 and 90,the differences were statistically significant(both P<0.05),and there were no statistical differences in other optical quality parameters between different axes(all P>0.05);In-1.50DC group and-2.00DC group,there were no statistically significant difference in all optical quality parameters between different axes(all P>0.05).Conclusion:In WTR and ATR,the visual acuity is worse when astigmatism axis close to 45.In-1.00DC astigmatism,the OSI of the axis close to 180 is smaller than axis close to 45 and 90.When astigmatism>-1.00DC,the optical quality parameters of different axial directions are all the same.