Visual rehabilitation in low-moderate keratoconus : intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

AIM: To present the results of same-day topography-guided photorefractive keratectomy (TG-PRK) and corneal collagen crosslinking (CXL) after previous intrastromal corneal ring segment (ISCR) implantation for keratoconus. METHODS: An experimental clinical study on twenty - one eyes of 19 patients aged 27.1±6.6y (range 19-43y), with low to moderate keratoconus who were selected to undergo customized TG -PRK immediately followed by same -day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities (UDVA) and corrected distance visual acuities (CDVA), keratometry (K) values, central corneal thickness (CCT) and coma were assessed 3mo after TG-PRK and CXL. RESULTS: After TG -PRK/CXL: the mean UDVA (logMAR) improved significantly from 0.66±0.41 to 0.20±0.25 (Ρ<0.05); Kflat value decreased from: 48.44±3.66 D to 43.71±1.95 D; Ksteep value decreased from 45.61±2.40 D to 41.56±2.05 D; Kaverage also decreased from 47.00±2.66 D to 42.42 ±2.07 D (Ρ<0.05 for all). The mean sphere and cylinder decreased significantly post - surgery from, - 3 . 10 ± 2 . 99 D to -0.11±0.93 D and from -3.68±1.53 to -1.11 ±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to post-ISCR, significant reductions (Ρ<0.05 or all) in all K values, sphere and cylinder were observed after TG-PRK/CXL. CONCLUSION: Same -day combined topography - guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low -moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma.