Topometric Indices And Corneal Densitometry Change After Corneal Refractive Surgery Combined With Simultaneous Collagen Crosslinking

Clin Ophthalmol. 2019 Sep 27;13:1927-1933. doi: 10.2147/OPTH.S225909. eCollection 2019.

Abstract

Purpose: To show the alteration of tomography, topometric indices and corneal densitometry after corneal refractive surgery combined with collagen crosslinking.

Patients and methods: All medical records of patients undergoing corneal refractive surgery with simultaneous collagen crosslinking during April 2015 and August 2018 were retrospectively reviewed. Corneal tomography, higher-order aberrations (HOA), topographic indices and corneal densitometry were evaluated. All the data at 1 month, 3 months and 6 months were compared to baseline value. All complications were noted. P value less than 0.05 was considered statistically significant.

Results: Medical records of fourteen patients (twenty-five eyes) were reviewed. HOA increased at all time points (p < 0.05). Keratoconus index and central keratoconus index decreased, whereas index of surface variance, index of vertical asymmetry, index of height decentration and the minimum of radius of curvature increased at all time points (p < 0.05). Index of height asymmetry increased at 3 and 6 months (p < 0.05). Corneal densitometry at anterior layer of 0-10 mm zone and center layer of 0-6 mm zone increased at 1 and 3 months (p < 0.05). At 6 months, the densitometry at 0-6 mm zone returned to baseline level. However, at 6 months, at anterior and center layer of 6-10 mm zone, the densitometry values were still more than preoperative values (p < 0.05). There was one case of bacterial keratitis.

Conclusion: After the corneal refractive surgery combined with collagen crosslinking, the HOA and corneal densitometry increased. Topographic indices showed conflicting results.

Keywords: LASIK; PRK; SMILE; Xtra; corneal densitometry; topometric index.