Efficacy and safety of vitrectomy for congenital cataract surgery: a systematic review and meta-analysis based on randomized and controlled trials.

PURPOSE: To explore the effectiveness and safety of vitrectomy for congenital cataract surgery. METHODS: We searched PubMed, Science Direct, The Cochrane Library, China National Knowledge Infrastructure and the Wanfang Database. Two researchers extracted data and assessed paper quality independently. Posterior capsule opacification (PCO) or visual axis opacification (VAO), reoperation rate, visual acuity, intraocular lenses (IOL) deposit, synechias, uveitis, secondary glaucoma, low-contrast sensitivity and IOL decentration were compared. RESULTS: We included 11 randomized controlled trials (RCTs) with 634 congenital cataract eyes. Cases of posterior capsule opacification in vitrectomy group were significantly less than that of control group, with risk ratio (RR) of 0.15 [95% confidence interval (CI): 0.09, 0.26], and there was no heterogeneity (I2  = 0%, p = 0.94). Reoperation rate in vitrectomy group was lower than that of control group either (RR = 0.40, 95%CI: 0.17, 0.94), and there was no heterogeneity (I2  = 0%, p = 0.85). Best-corrected visual acuity (BCVA) measured in LogMAR unit of vitrectomy group was smaller, with a mean difference (MD) of -0.17 (95%CI: -0.28, -0.05), and I2 was only 22%, indicating of a small heterogeneity. No statistical difference was found between two groups on IOL deposit (RR = 1.23, 95%CI: 0.70, 2.17), and the heterogeneity was small (I2  = 16%, p = 0.31). No statistical difference was found between two groups on synechias (RR = 1.08, 95%CI: 0.60, 1.94), with a quite small heterogeneity (I2  = 3%, p = 0.38). No statistical difference was found between two groups on uveitis (RR = 0.55, 95%CI: 0.15, 2.01), and there was no heterogeneity (I2  = 0%, p = 0.94). There was no statistical difference on IOP either, with a MD of 0.25 (95%CI: -1.56, 2.07), and there was no heterogeneity (I2  = 0%). Egger's test showed that there was no publication bias for all assessed outcomes. Low-contrast sensitivity was better in the vitrectomy group. And no evidence indicated vitrectomy could lead to a higher risk on secondary glaucoma or IOL decentration. CONCLUSION: Vitrectomy helps lower the PCO risk and reoperation risk after congenital cataract surgery, and also, vitrectomy helps patients gain a better BCVA and achieve a better low-contrast sensitivity, with no trade-off on IOP control, IOL deposit, synechias, uveitis and secondary glaucoma. We recommend performing vitrectomy during congenital cataract surgery.

Effect of microkeratome suction duration on corneal flap thickness and incision angle.

PURPOSE: To determine the effect of suction duration on corneal flap thickness and incision angle of the cut margin created by a microkeratome in a porcine eye. METHODS: Thirty porcine eyes were randomly assigned to three groups according to different suction duration: group 1 (10 sec), group 2 (35 sec), and group 3 (60 sec). The Hansatome microkeratome with a #160 plate and 8.5-mm-diameter suction ring was used to create a corneal flap with a diameter of 8.5 millimeters. Corneal flap thickness was measured by automated ultrasonic pachymetry, and the incision angle was assessed by measuring the angle of a sagittal section of the cornea using image analysis software. RESULTS: Mean corneal flap thickness in groups 1 (10 sec), 2 (35 sec), and 3 (60 sec) was 87.8 +/- 22.0 microm, 116.0 +/- 7.0 microm, and 127.2 +/- 16.8 microm, respectively. There was a statistically significant difference between groups 1 (10 sec) and 2 (35 sec) (P=.005) and groups 1 and 3 (P=.004). The mean incision angle in groups 1, 2, and 3 was 34.8 +/- 9.0 degrees, 44.4 +/- 16.1 degrees, and 48.24 +/- 15.3 degrees, respectively. A statistically significant difference was found between groups 1 (10 sec) and 2 (35 sec) (P=.044) and groups 1 (10 sec) and 3 (60 sec) (P<.001). CONCLUSION: In laser in situ keratomileusis in porcine eyes, an increase in suction duration resulted in a thicker flap and greater incision angle.