Comparison of astigmatism correction using shorter arc length 90°/120° asymmetric intacs severe keratoconus versus 150° single-segment intacs severe keratoconus in asymmetric keratoconus.

Objective: 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.

Methods: 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.

Results: 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).

Conclusions: 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.