Quantitative examination of different types of intraocular straylight in age-related cataract and its clinical significance / 中华实验眼科杂志

ABSTRACT

Background The test for visual acuity is the conventional standard for evaluating visual quality.However,there is little correlation between visual acuity and visual disability.Therefore,other clinical observations such as contrast sensitivity or straylight have been used in the clinical assessment of visual quality after cataract surgery.Objective This study was to examine the change in the amount of straylight in cataractous eyes and to evaluate the correlation of the types of cataract with visual quality.Methods A non-randomized case-controlled study was designed.Eighty eyes of 40 patients with age-related cataract were enrolled in this study,including 22 eyes with hard nucleus cataract,19 eyes with cortical cataract,23 eyes with mixed cataract and 16 eyes with posterior subcapsular cataract diagnosed based on the criteria from Lens Opacities Classification System Ⅲ(LOCS Ⅲ).The values for straylight and best corrected visual acuity (BCVA) were measured with the C-quant straylight meter and Snellen chart,respectively.The differences in the straylight values among the different types of cataract were analyzed,and the correlation of the straylight value with age or BCVA was assessed.Forty eyes of 40 age-matched normal people served as controls.Results Examination was completed in sixty-two eyes of 31 patients in the cataract group at a completion rate of 77.5％,and all the subjects in the control group finished the examination at a rate of 100％.The mean straylight value was (2.06±0.88) log in the cataract group and (1.96±0.42) log in the control group,showing a significant difference between them (t =3.251,P＜0.01).The respective mean C-quant measurements for hard nucleus cataract,cortical cataract,nuclear-cortical cataract and posterior subcapsular cataract patients were (1.96±0.42) log,(1.91 ±0.16) log,(2.05 ±0.19) log and (2.48 ±0.66) log,respectively,with a significant difference among these four groups (F =2.156,P =0.019).The highest straylight value was detected in the posterior subcapsular cataract group.The straylight value was enlarged with the increase of age with a regression equation of Y=0.0010X+ 1.025 in the hard nucleus cataract group (r =0.455,P ＜ 0.05).In addition,the negative linear correlation was found between the straylight value and BCVA in both the hard nucleus cataract group and cortical cataract group (r=-0.590,-0.697,P＜0.01).However,no correlation was found in the mixed cataract group and posterior subcapsular cataract group (r =-0.240,-0.235,P＞0.05).Conclusions The C-quant straylight meter can objectively reflect the visual function for hard nucleus and cortical cataractous eye.Posterior subcapsular cataract produces straylight and exerts a great influence on visual quality due to early glare sensation,so it should be benefit to perform surgery earlier.