Comparison of Astigmatism Correction Using Shorter Arc Length 90°/120° Asymmetric Intacs Severe Keratoconus Versus 150° Single-Segment Intacs Severe Keratoconus in Asymmetric Keratoconus

Abstract

To compare astigmatism correction using shorter arc length 90°/120° asymmetric Intacs severe keratoconus (SK) versus 150° single-segment Intacs SK in cases of asymmetric keratoconus. Retrospective prospective study in patients of asymmetric keratoconus with more than 2 diopters (D) of refractive astigmatism. Group 1 included 16 eyes of 16 patients who underwent 150° single-segment Intacs SK implantation, and group 2 included 16 eyes of 12 patients who underwent asymmetric shorter arc length 90°/120° Intacs SK implantation. Patients younger than 35 years were cross-linked. Parameters studied included preoperative and postoperative (1 and 9 months) uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (CDVA), manifest refraction, and corneal topography. Both groups demonstrated significant improvement in UDVA, CDVA, spherical equivalent (SE), and manifest cylinder after the surgery. Comparison of change (post-pre) in UDVA, CDVA, and SE at the 1- and 9-month postoperative visits demonstrated significant improvement without statistically significant difference between the 2 groups. However, change in manifest cylinder at 1 month was statistically significantly higher in group 2 (4.65 ± 2.21 D) versus group 1 (2.29 ± 1.57 D) (P = 0.001). At the 9-month visit, change in manifest cylinder continued to be higher at 3.43 ± 1.79 D in group 2 versus 2.58 ± 1.29 D in group 1; however, this difference was not statistically significant (P = 0.17). Implantation of asymmetric shorter arc length 90°/120° Intacs SK segments achieved 33% higher correction of astigmatism compared with 150° single-segment Intacs SK implantation. Improvement in UDVA, CDVA, and SE was comparable.