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

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).

In this prospective interventional study conducted at a tertiary care centre, 40 eyes of 40 consecutive senile cataract patients with 1.00-3.00 D corneal astigmatism were enrolled for the study. MSICS by modified Blumenthal's technique was performed through 6.0, 6.5, and 7.0 mm on-axis incision in 1.0-1.49 D (group A), 1.50-1.99 D (group B), and 2.00-3.00 D (group C) astigmatism, respectively. Surgically induced astigmatism (SIA) was calculated by vector analysis and double angle plots (DAP) at 12 weeks postoperatively.

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.

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.