| With the development of surgical techniques and various toric intraocular lenses (IOLs) and multifocal IOLs, phacoemulsification with foldable IOLs implantation has been referred to as refractive surgery. Especially surgery navigation system, femtosecond laser-assisted cataract surgery, and implantation of multifocal toric IOLs, have pushed cataract surgery into a zero error and no knife period. Accuracy of predicting postoperative refraction is of great importance. Because patients need good uncorrected visual acuity (UCVA) instead of the best corrected visual acuity (BCVA) to face the rapid development of science and technology. Despite of more precise biometry techniques and IOL power calculation formula, postoperative refractive shift can be noticed in some patients. Effective lens position (ELP) of an IOL with a given power determines postoperative refraction. The variations of ELP result in refractive error change after surgery. Frontward motion of the IOL leads to myopia, while rearward movement causes hyperopia. The change of ELP reflects the interaction between capsule bag fusion and the fibrotic reaction of the capsule, which lead to capsule contraction and forces to move forward and backward. The change of ELP is the result of the forces imbalance. Residual lens epithelial cells (LECs) after surgery play a major role in the pathogenesis of capsule contraction and fibrosis. Contact with the intraocular lens optic causes the LECs of anterior capsule to undergo myofibroblastic transdifferentiation, resulting in fibrotic anterior capsule opacificaiton (ACO), and contraction of capsulorhexis aperture. Fibrofic posterior capsule opacification (PCO) is caused by anterior LECs that have migrated onto the posterior capsule, where they cause whitening and shrinkage. Regeneratory PCO is caused by equatorial LECs originating from the germinative zone of the capsular bag.Object To evaluate the effects of anterior capsule polishing on ELP and capsular bag stability, the LECs of the anterior capsule and the equatorial LECs were removed by anterior capsule polishing in the uneventful phacoemulsification with in-the-bag IOL implantation, and ELP, UCVA and SER were measured from lday to 6 months after surgery.Methods In this prospective randomized bilateral double-masked controlled clinical study, inclusion criteria were bilateral age-related cataract with good overall physical constitution who were treated from January 2013 to January 2014 in our hospital, and had uneventful surgeries of both eyes with in-the-bag IOL implantation. Exclusion criteria included history of intraocular surgery or laser therapy, history of ocular trauma or ocular disease, high myopia, corneal astigmatism>1.00D, diabetes, severe fundus pathology and patients who could not return on time.Patients recruited underwent necessary chemical tests and physical examination. IOL power was decided to obtain postoperative refraction at around-0.50 diopter (D) with SRK/T, HOLLDAY 1 and Haigis formula. Preoperative BCVA was recorded and converted to the logMAR scale. Anterior chamber depth (ACD) was measured with Visante anterior segment Optical Coherence Tomograph (AS-OCT).All surgeries were operated by the same surgeon. The surgeon remained masked for the procedure to be performed until completing cortex aspiration. Polishing anterior capsule in one eye was chosen randomly, and the other not as the control. Randomization method was Biased Coin Design.360 degree polishing was operated with Whitman Shepherd double-ended capsule polisher. An Acrysof IQ SN60WF was implanted in the bag.ELP was measured 1 day,1 week,1 month,3 months and 6 months postoperatively using AS-OCT. The measurements and images analyses were performed by the same technician. Patients and the technician remained masked for polishing or not until the end of the study. The measurements were performed in a room with a standard dim illumination after full dilatation of the pupil. ELP was defined as the distance between the posterior surface of the corneal and the anterior surface of IOL in the pupil center, along the optical axis. The actual axial movement of IOL was defined as the root mean square (RMS) of the change in ELP at each visit.The UCVA recorded in logMAR units, Spherical equivalent refraction (SER) was used in subsequent calculations.Results A total of 40 eyes of 20 patients were included, and 10 patients (50%) were men. The mean age of them was 70.5±7.6 years (range 56 to 79 years). The BCVA of the control group and the polished group was 0.60±0.28 and 0.69±0.66, and there was no significant difference of them (P=0.27). The ACD of the control group and the polished group was 3.21±0.37mm and 3.14±0.24mm, and there was no significant difference of them (P=0.53). The IOL power of the control group and the polished group was 22.5±2.6D and 22.2±3.4D, and there was no significant difference of them (P=0.21). The Predicted refraction of the control group and the polished group was-0.38±0.35D and-0.46±0.32D, and there was no significant difference of them (P=0.13). The BCVA of the control group and the polished group was 0.60±0.28 and 0.69±0.66, and there was no significant difference of them (P=0.27). All the patients underwent uneventful surgeries without intraoperative or postoperative complications, and returned on time for measurements.The mean ELP of the control group was 3.97±0.27mm at 1 day,3.93±0.25 mm at 1 week,3.97±0.22 mm at 1 month,3.98±0.24 mm at 3 months, and 3.92±0.25 mm at 6 months postoperatively. The mean ELP of the polished group was 4.02±0.32 mm at 1 day,3.99±0.29 mm at 1 week,3.99±0.26 mm at 1 month,3.97±0.27 mm at 3 months, and 3.97±0.28 mm at 6 months postoperatively. In the first postoperative week, IOLs of the control group moved forward slightly; From 1 week to 3 months, the IOLs moved backward slightly; From 3 months to 6 months, the IOLs moved forward slightly. IOLs of the polished group were very stable during the postoperative 6 months. There were no significant differences of mean ELP among different visits in both groups (control:F=0.19, P=0.94; polished:F=0.08, P=0.99), and no significant differences were observed between mean ELP of the control group and the polished group (1 day:P=0.26; 1 week:P=0.10; 1 month:P=0.41; 3 months:P=0.94; 6 months: P=0.19). However, the ELPrms of the control group was 0.07±0.02 mm, and the ELPrms of the polished group was 0.05±0.02 mm. The ELPrms of the polished group was smaller than that of the control group during the postoperative 6 months (P=0.005).The uncorrected visual acuity of the control group was 0.07±0.10 at 1 day,0.08±0.09 at 1 week,0.09±0.10 at 1 month,0.10±0.12 at 3 months, and 0.10±0.11 at 6 months postoperatively. The uncorrected visual acuity of the polished group was 0.07±0.09 at 1 day,0.08±0.09 at 1 week,0.08±0.09 at 1 month,0.10±0.08 at 3 months, and 0.10±0.08 at 6 months postoperatively. The values of both groups did not change significantly at each time point (control:F=0.260, P=0.903; polished:F=0.534, P=0.711), and no significant differences were observed between the control group and the polished group (1day:P=0.87; 1 week:P=0.84; 1 month:P=0.73; 3 months: P=0.89; 6 months:P=0.87).The refractive error in the control group was -0.33±0.18 D at 1 day,-0.42±0.26 D at 1 week,-0.37±0.24 D at 1 month,-0.36±0.23D at 3 months, and -0.41±0.22 D at 6 months postoperatively. For the polished group, the refractive error was -0.45±0.18 D at 1 day, -0.53±0.44 D at 1 week,-0.46±0.47 D at 1 month,-0.48±0.22 D at 3 months, and -0.48±0.21 D at 6 months after surgery. The values of both groups did not change significantly at each time point (control:F=0.474, P=0.754; polished:F=0.391, P=0.815), and no significant differences were observed between the control group and the polished group (1day:P=0.06; 1 week P=0.19; 1 month P=0.25; 3 months:P=0.07; 6 months:P=0.32).There was a positive correlation between change of mean ELP and postoperative refraction change (r=0.15, P=0.03).Conclusions Whitman Shepherd double-ended capsule polisher was used to remove the LECs of the anterior capsule and the equatorial LECs with the help of red light reaction. No intraoperative or postoperative complications were noticed during the study. It is noninvasive and quick to using AS-OCT to measure ELP, so measurements can be done the first day after surgery. Patient even elderly people were able to complete this easy measurement without any discomfort. We suggested that the same skilled technician complete the measurements and the data analysis. There might be error during analysis of data performed by different technicians. SN60WF displayed little axial shift as well as stable refraction error and UCVA throughout the follow-up. Polishing anterior capsule intraoperatively improved the axial position stability of the IOL in the long term. |
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