Residual Refractive Astigmatism following Toric Intraocular Lens Implantation without Consideration of Posterior Corneal Astigmatism during Cataract Surgery with Low Anterior Keratometric Astigmatism upto 2.5 Dioptres.

Purpose: To determine the refractive astigmatism following toric intraocular lens (tIOL) implantation without consideration of posterior keratometric astigmatism with a conventional tIOL calculator for eyes with low keratometric astigmatism (0.75D to 2.5D) and to theoretically compare the outcomes with predicted refractive astigmatism using a calculator with Barrett's formula.Methods: 34 eyes (34 patients) were assessed with Scheimpflug imaging and underwent tIOL implantation employing conventional tIOL calculator. Eyes were grouped on preoperative keratometric astigmatism as against-the-rule (ATR), with-the-rule (WTR), and oblique (OB). The refractive astigmatism was assessed at 1, 3, 6 and 12 months postoperatively and was classified as ATR, WTR, and OB. Theoretical refractive astigmatism calculations were performed for the same eyes using Barrett's formula.Results: Preoperatively keratometric astigamtism was ATR, WTR, and OB in 32%, 53% and 15% of eyes. At 12 months, in ATR, WTR and OB groups, 45.5%, 16.7% and 60% had ATR refractive astigmatism; 16.7%, 0%, and 20% had WTR refractive astigmatism; 55.6%, 54.5% and 20% were emmetropic (no sphere and cylinder) respectively. There was a significant difference between the theoretical predicted postoperative refractive astigmatism using conventional tIOL calculator and Barrett's formula (P < .05). Postoperative refractive astigmatism was not significantly different from the theoretical predicted refractive astigmatism with Barrett's formula but it was significantly higher than that with a conventional tIOL calculator.Conclusions: At 12 months, with a conventional tIOL calculator, postoperative emmetropia is achieved in half, two third and one-fifth of eyes with preoperatively ATR, WTR, and OB keratometric astigamtism respectively. Around 1/4th WTR keratometric astigamtism eyes preoperatively were overcorrected to ATR refractive astigmatism whereas ½ATR remained undercorrected at 12 months Outcomes achieved were dissimilar to predicted outcomes with a conventional tIOL calculator but similar to those with Barrett's formula.

Influence of peripheral corneal relaxing incisions during cataract surgery for corneal astigmatism up to 2.5 dioptres on corneal densitometry.

PURPOSE: To assess the effect of peripheral corneal relaxing incisions (PCRI) for astigmatism between 0.75 and 2.5 dioptres during cataract surgery on corneal densitometry (CD). METHODS: In this prospective, randomised study, 80 eyes (80 patients), received either tIOL or PCRI. Assessment at pre-operative and 1, 3, 6, 12 months post-operative visit included uncorrected (UCDVA) and best-corrected distance visual acuity (BCDVA), spherical equivalent (SEQ) (only post-operatively), mean anterior and posterior keratometric astigmatism (KA) and CD with Schiempflug system. CD was analysed in four concentric radial zones from centre to periphery (Zone 1 to 4) and in 3 layers (anterior, mid-stromal and posterior). RESULTS: Comparing tIOLs vs. PCRIs, there was no significant difference in the UCDVA, BCDVA and SEQ. In PCRI group, anterior KA decreased at 1 month and remained stable thereafter. For zones 1, 2 and 3, CD significantly reduced after 3 months with tIOLs whereas with PCRIs, it reduced 1 month onwards. For zone 4, CD reduced only at 12 months with tIOLs compared to 3 months onwards with PCRIs. In both groups CD was higher in the zone 4 and anterior layer. Significant reduction in CD was found in all three layers of cornea after 3 months in tIOL and after first month in PCRI groups, respectively. CONCLUSIONS: Cataract surgery alone reduces the CD. Reducing keratometric astigmatism with PCRIs shows significant differences in CD from early post-operative period for central and anterior corneal layer.

Toric Intraocular Lenses Versus Peripheral Corneal Relaxing Incisions for Astigmatism Between 0.75 and 2.5 Diopters During Cataract Surgery.

PURPOSE: To compare the outcomes after toric intraocular lens (tIOL) or peripheral corneal relaxing incisions (PCRI) for keratometric astigmatism (KA) between 0.75 and 2.5 diopters (D) during cataract surgery. DESIGN: Prospective randomized clinical trial. METHODS: Eighty eyes (80 participants) received either tIOL or PCRI and were assessed preoperatively, 1, 3, 6, and 12 months postoperatively. PRIMARY OUTCOME MEASURE: Uncorrected (UCDVA) and best-corrected distance logMAR visual acuity (BCDVA) at 12 months. SECONDARY OUTCOME MEASURES: Uncorrected near visual acuity (UCNVA), manifest refraction, KA and mean keratometry (KM), corneal aberrometry, tIOL rotation, and quality-of-life questionnaire. RESULTS: Comparing tIOLs vs PCRIs, there was no significant difference in the UCDVA, BCDVA, and UCNVA. At 12 months, 61% vs 53% had UDCVA of 20/25 or better, 100% vs 76% gained ≥1 lines, and 59% vs 43% were within ±0.13 D spherical equivalent. In the PCRI group, anterior KA decreased at 1 month and remained stable thereafter; there was a nonsignificant trend toward a flatter posterior KA and steeper posterior KM and the total corneal Z2-2 was low at 1 and 12 months. Over 12 months, there were changes in posterior corneal tilt, coma, and hexafoil in the PCRI group. The mean rotation of the tIOLs at 12 months was 1.8 ± 1.4 degrees. tIOL patients were happier and were glad to use the nonprescription sunglasses. CONCLUSION: There was no difference in visual acuity, although more tIOL patients gained ≥1 line and were within ±0.13 D. After PCRIs, the anterior KA decreased in the early postoperative period and remained stable thereafter and posterior corneal aberrations changed constantly over 12 months.