RESUMEN
Purpose: To compare the outcome of Collagen cross‑linking (CXL) with that following topography‑guided customized ablation treatment (T‑CAT) with simultaneous CXL in eyes with progressive keratoconus. Materials and Methods: This was a prospective, non‑randomized single centre study of 66 eyes with progressive keratoconus. Of these, 40 eyes underwent CXL and 26 eyes underwent T‑CAT + CXL. The refractive, topographic, tomographic and aberrometric changes measured at baseline, 1, 3 and 6 months post‑operatively were compared between both groups. Results: After a mean follow‑up of 7.7 ± 1.3 months, the mean retinoscopic cylinder decreased by 1.02 ± 3.16 D in the CXL group (P = 0.1) and 2.87 ± 3.22 D in the T‑CAT + CXL group (P = 0.04). The Best corrected visual acuity increased by 2 lines or more in 10% of eyes in the CXL group and in 23.3% of eyes in the T‑CAT + CXL group. The mean steepest‑K reduced by 0.40 ± 3.71 D (P = 0.77) in the CXL group and by 2.91 ± 2.01D (P = 0.03) in the T‑CAT + CXL group. The sag factor and surface asymmetry index showed no significant change in the CXL group but reduced by 3.59 ± 5.94 D (P = 0.01) and 0.72 ± 1.18 (P = 0.02) respectively in the T‑CAT + CXL group. There was a significant increase in the highest posterior corneal elevation in both groups (9.57 ± 14.93 μ in the CXL group and 7.85 ± 9.25 μ in the T‑CAT + CXL group, P ≤ 0.001 for both). There was significantly greater reduction of mean coma (P < 0.001) and mean higher‑order aberrations (P = 0.01) following T‑CAT + CXL compared to CXL. Conclusions: CAT + CXL is an effective approach to confer biomechanical stability and to improve the corneal contour in eyes with keratoconus and results in better refractive, topographic and aberrometric outcomes than CXL alone.
RESUMEN
Keratoconus is a progressive ectatic disorder of the cornea which often presents with fluctuating refraction and high irregular astigmatism. Correcting the vision of these patients is often a challenge because glasses are unable to correct the irregular astigmatism and regular contact lenses may not fit them very well. Topography-guided custom ablation treatment (T-CAT) is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and possibly contact lens fit. The aim of the procedure is not to give a complete refractive correction. It has been tried with a lot of success by various groups of refractive surgeons around the world but a meticulous and methodical planning of the procedure is essential to ensure optimum results. In this paper, we attempt to elucidate the planning for a T-CAT procedure for various types of cones and asphericities.