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

摘要

AIM:To present the results of same-day topographyguided 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 twentyone 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(P 0.05); Kflatvalue decreased from: 48.44±3.66 D to43.71±1.95 D; Ksteepvalue decreased from 45.61±2.40 D to41.56±2.05 D; Kaveragealso decreased from 47.00±2.66 D to42.42 ±2.07 D(P 0.05 for all). The mean sphere andcylinder 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 postISCR, significant reductions(P 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.