Correction of pre-existing astigmatism by on-axis incision size modulation in manual small-incision cataract surgery

Purpose: To study the effect of wound size modulation on pre?existing astigmatism by on?axis placement of incision in manual small?incision cataract surgery (MSICS). Methods: In this prospective interventional study conducted at a tertiary care centre, 40 eyes of 40 consecutive senile cataract patients with 1.00�00 D corneal astigmatism were enrolled for the study. MSICS by modified Blumenthal抯 technique was performed through 6.0, 6.5, and 7.0 mm on?axis incision in 1.0�49 D (group A), 1.50�99 D (group B), and 2.00�00 D (group C) astigmatism, respectively. Surgically induced astigmatism (SIA) was calculated by vector analysis and double angle plots (DAP) at 12 weeks postoperatively. Results: There were 22 males and 18 females with mean age of 58.12 � 1.18 years. The mean SIA at 12 weeks was 0.85 � 0.28 D in group A (17 eyes), 1.32 � 0.65 D in group B (10 eyes), and 1.91 � 0.69 D in group C (13 eyes). The overall median uncorrected visual acuity was 0.18 (IQR = 0 to 0.2). The mean astigmatism decreased from 1.95 � 0.74 D to 1.04 + 0.57 D (P = 0.00) in superior incision and from 1.70 + 0.50 D to 0.92 � 0.45 D (P = 0.00) in temporal incision group with central shift of centroid in all cases. Conclusion: The customization of on?axis external incision size can be used to manage pre?existing corneal astigmatism of less than 3.00 D using both temporal and superior incisions effectively

Analysis of Changes in Anterior, Posterior and Total Corneal Astigmatism after On-Axis Cataract Surgery

PURPOSE: To assess the changes in anterior, posterior, and total corneal astigmatism after cataract surgery with on-axis clear corneal incision cataract surgery. METHODS: This study included 48 eyes (24 eyes with 'with-the-rule [WTR]' and 24 eyes with 'against-the-rule [ATR]') that underwent phacoemulsification and intraocular lens insertion through on-axis clear corneal incision. The ATR group with vertically steep axis of posterior corneal astigmatism was divided into subgroups 1 and 2 for the opposite axis. Autorefraction, uncorrected and best-corrected visual acuities were measured. Corneal astigmatism (anterior, posterior and total) was measured using Pentacam(R) preoperatively and 1 week, 1 month, and 2 months postoperatively. RESULTS: Multivariate linear regression analysis of preoperative data showed positive correlations among anterior, posterior and total astigmatism. Anterior corneal astigmatism showed a significant decrease in both WTR and ATR groups in all measured points (all p 0.05) and significant decrease in the ATR subgroup 1 (p 0.05). According to correlation analysis based on trend line equations, 1.7 diopters of anterior astigmatism could expect 0.3 diopters of posterior astigmatism and 0.5 diopters of total astigmatism for the WTR group and 0.4 diopters of anterior astigmatism could expect 0.2 diopters of posterior astigmatism and 0.4 diopters of total astigmatism for the ATR group. CONCLUSIONS: Considering the majority of cataract patients have vertically steep posterior corneal astigmatism, temporal incision for ATR patients is generally effective. Moreover, for patients with WTR astigmatism of more than 1.7 diopters or ATR astigmatism greater than 0.8 diopters, additional preoperative correction based on posterior astigmatism is needed for more precise prediction of postoperative total corneal astigmatism.

Comparison of Higher Order Aberrations and Astigmatism after On-Axis Small Incision Cataract Surgery

PURPOSE: To assess the changes of corneal astigmatism and higher order aberrations (HOAs) of the anterior and posterior corneal surface after cataract surgery with on-axis clear corneal incision in eyes with-the-rule (WTR) astigmatism and against-the-rule (ATR) astigmatism. METHODS: This study included 50 patients who underwent phacoemulsification and IOL insertion through a 2.8-mm on-axis clear corneal incision. The eyes were divided into two groups: (1) 26 eyes with WTR astigmatism with a superior incision and (2) 24 eyes with ATR astigmatism with a temporal incision. During the follow-up period, visual acuity was measured, and the surgically induced astigmatism (SIA) and HOAs of the anterior and posterior corneal surface were measured with Pentacam(R) (Occlus, Wetzlar, Germany) preoperatively and 1 week, 1 month, and 2 months postoperatively. RESULTS: There were no significant differences in UCVA and BCVA between the two groups. HOAs increased in both groups 1 week after surgery, but no significant differences were found between the groups (p > 0.05). Surgically induced astigmatism was larger in the WTR group than in the ATR group (p < 0.05). At postoperative 2 months, there were significant differences in HOAs between the two groups, and there were statistically significant differences in HOAs, oblique trefoil at front side, and in HOAs, horizontal coma at rear side (p < 0.05). CONCLUSIONS: In conclusion, superior incision in eyes with WTR astigmatism resulted in higher SIA compared to temporal incision in eyes with ATR astigmatism. Moreover, HOAs was significantly decreased in eyes with WTR astigmatism with superior incision. Thus, superior incision could be more effective in reducing corneal astigmatism in eyes with WTR astigmatism.