Influence of corneal astigmatism and central corneal thickness on vision following small-incision phacoemulsification

Abstract

Background Small incision cataract surgery combined with intraocular lens (IOL) implantation remains a popular way for cataract.However,some factors affect the postsurgical visual outcomes and lower the patients' satisfaction,including intraoperative and postoperative complications as well as corneal refractive and thickness changes.Objective This study was to evaluate the influence of corneal refractive and thickness changes on visual fluctuation after 2.6 mm temporal incision surgery for cataract.Methods A series cases-observational study was designed.Twenty-nine eyes of 25 age-related cataract patients received 2.6 mm temporal transparent incision phacoemulsification and IOL implantation from November,2011 through April,2012 in Eye & ENT Hospital of Fudan University under the informed consent.The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),automatic and subjective refraction were examined,and the central corneal thickness (CCT) and corneal vector astigmatism were measured using Pentacam analysis system before and after operation.The examination outcomes were compared among different time points,and the influencing factors of UCVA or BCVA were analyzed.Results The mean UCVA (LogMAR) was 0.52±0.06 in 1 day and 0.64±0.07 in 2 months after surgery,with a significant difference between them (t=-3.051,P＜0.05).The mean BCVA (LogMAR) was 0.24±0.04 and 0.13± 0.04 in postoperative 1 day and 2 months,showing a significant difference between them (t =-3.031,P＜0.05).Spherical equivalents (SE) were (-1.74±0.28) D,(-1.99±0.27) D and (-1.69±0.24) D in postoperative 1 day,14 days and 60 days,respectively,with a significant difference among the 3 time points (F =3.562,P =0.039),and significant difference also was found between postoperative 1 day and 14 days (t =2.515,P＜0.05) or between postoperative 14 days and 60 days (t =-2.987,P ＜ 0.05).The preoperative J0 value was (0.06 ± 0.06) D,and postoperative J0 value was (0.29±0.08) D on the first day,which was significant higher than that in preoperation (t =-4.625,P＜0.01).In addition,J0 value showed a significant difference between postoperative 1 day and 14 days (t=-7.858,P＜0.01) as well as between postoperative 14 days and 2 months ([0.38±0.07] D versus [0.27±0.07] D,t=-5.649,P＜0.01).The mean CCT was (547.1±25.3) μm,(599.4±56.9) μm,(557.0±27.1) μm and (551.0 ± 25.9) μm before and 1 day,14 and 60 days after operation,with significant differences among the various time points (F =9.792,P ＜ 0.001),and significant differences also were seen in the CCT between preoperation and postoperative 1 day (t =-5.116,P＜0.01),between postoperative 1 day and 14 days (t =4.135,P＜ 0.01),between postoperative 14 days and 60 days (t=2.082,P＜0.05).UCVA=0.513-1.183×C J45(F=16.724;t=-4.089,P=0.026) and BCVA=-1.314+0.003×CCT (F=22.322;t=4.725,P=0.018).Conclusions The UCVA remains a downward trend,and BCVA sustains upward trend after 2.6 mm temporal transparent incision phacoemulsification combined with IOL implantation surgery.Postoperative UCVA is affected by corneal astigmatism change,while BCVA is influenced by CCT change. Key words: Phacoemulsification; Visual acuity; Central corneal thickness; Astigmatism