Racemization is probably the most abundant post-translational modification (PTM) in aged lens.According to previous studies,L-amino acid in α,β and γ crystallins are tend to transfer into D-amino acid with aging,leading to a series of age-related changes in the structure,metabolism and function of lens.Aggregated highmolecular-weight proteins gradually accumulate in both nuclear and cortex region,which will have a negative effect on the function of crystallins and finally lead to capacity of lens.Moreover,it is likely that racemization of crystallins eventually leads to cataract formation and development as well.The material effect and mechanism of racemization changes in human age-related lens still requires further research.

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.

With increasing age, more and more patients with posterior chamber intraocular lens (ICL) implantation are facing the threat of cataracts to their visual acuity.When examining the eyes of cataract patients after ICL surgery, attention should be paid to whether the density of corneal endothelial cells is greater than 2 000 cells/mm 2, the state of the anterior chamber angle, and whether there are fundus abnormalities such as retinal detachment and choroidal neovascularization.When conducting eye biometry measurement, attention should be paid to the measurement starting and ending lines of anterior chamber depth and lens thickness.If patients undergo ICL combined with corneal refractive surgery, they should be examined with two or more devices to obtain corneal refractive power according to the examination requirements after corneal laser vision correction.When selecting the type of intraocular lens, consideration should be given to the histological characteristics of high myopia.Compared to C- and L- loops, plate-haptic is relatively more stable in patients with high myopia accompanied by large capsules and larger diameters of continuous curvilinear capsulorhexis.Kane, Barrett Universal Ⅱ, Olsen, Hill-RBF formulas for calculating the refractive power of intraocular lenses are more accurate in people with long axial length.It is recommended to perform ICL removal simultaneously with phacoemulsification and intraocular lens implantation, preferably with a surgical incision greater than 2.6 mm.Femtosecond laser assisted cataract extraction surgery, although superior to traditional phacoemulsification in reducing corneal endothelial cell loss, reducing corneal edema, and high-quality capsulorhexis, can cause incomplete capsulorhexis and fragmentation due to the cavitation bubbles, manual adjustment of location, and the impact of lower vault.It is recommended to use it with caution.Ophthalmologists should fully understand and pay attention to the characteristics and difficulties of cataract surgery after ICL surgery, communicate fully with patients, and make personalized surgery to achieve better visual outcomes.