Objective To evaluate the effects of intraocular lenses (IOL) of silicone and polymethylmethacrylate (PMMA) on posterior capsule opacification (PCO). Methods We searched MEDLINE (1966 to 2003), EMBASE (1980 to 2003), Cochrane Central Register of Controlled Trials (Issue 1, 2003) and CBMdisc (1979 to 2003). Only randomized controlled trials (RCTs) were identified. Two reviewers independently assessed the quality of the included trial and extracted data. The following outcomes were assessed: PCO index, percentage of neodymium: YAG (Nd: YAG) laser posterior capsulotomy and visual acuity after cataract surgery. RevMan 4.2 was used for meta-analysis.Results Nine RCTs including 672 eyes were included. In patients with senile cataract, the results of meta-analysis suggested that silicone lens were better than PMMA lens on PCO index (the pooled SMD=－0.92, 95%CI －1.19 to －0.64) and percentage of Nd: YAG (the pooled OR 0.35, 95%CI 0.22 to 0.57) with a statistically significant difference, but there was no significant difference on visual acuity (the pooled OR 1.22, 95%CI 0.43 to 3.50) after cataract surgery between silicone lens and PMMA lens. However, in patients with uveitic cataract, the results of meta-analysis showed that PMMA lens were better than silicone lens in visual acuity (the pooled OR 0.38, 95%CI 0.15 to 0.91) after cataract surgery with a statistically significant difference, but there was no significant difference on PCO index (SMD 0.23, 95%CI －0.59 to 1.05) and percentage of Nd: YAG (the pooled OR 1.82, 95%CI 0.47 to 6.95) between silicone lens and PMMA lens. Conclusions Current evidence indicates that silicone lens are superior to PMMA lens in reducing PCO. Further trials with high quality on methodology are required.
ObjectiveTo use ultrasound biomicroscope (UBM) to observe the zonules in patients before cataract surgery and study the relation between the length of zonules and axial length (AL), so as to understand the underlying anatomical and pathological basis of factors influencing the stability of lens capsule in high axial myopic patients and provide objective theoretical references for surgical risk reduction and postoperative follow-up guidance. MethodsFifty-five patients (55 eyes) proposed to receive phacoemulsification between October 2014 and October 2015 were divided into group A (AL < 26 mm, n=21), group B (26 mm≤AL < 29 mm, n=14), and group C (AL≥29 mm, n=20) according to their AL.UBM examination was conducted preoperatively.Through measuring the length of zonules in supine position at 12, 3, 6, and 9 o'clock respectively, we compared the difference of the length of zonules among those three groups, and explored the correlation between the length of zonules and axial length. ResultsThe average length of zonules in group A was (0.67±0.13) mm, while that in group B and group C was (0.93±0.29) and (0.98±0.19) mm, respectively.The length of zonules in group A was shorter than that in group B and Group C, and the differences were statistically significant (P < 0.001);and that in group B was shorter than that in group C, but the difference was of no statistical significance (P=0.331).In the correlation analysis between axial length and the average length of zonules, the length of zonules was positively correlated with the axial length (r=0.502). ConclusionsUBM provides a quantitative method for observing zonules.In the assessment before cataract surgery, it is a more accurate method for evaluation of zonules, and probably has a certain value in pre-assessment of intra ocular lens dislocation after cataract surgery.