title: Visual rehabilitation in low-moderate keratoconus: intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking.
abstract: OBJECTIVE
  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 (P<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 (P<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 (P<0.05 or all) in all K values, sphere and cylinder were observed after TG-PRK/CXL.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Optometry & Vision Sciences, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433, Saudi Arabia.
authors.forename: Ferial M
authors.initials: FM
authors.lastname: Zeraid
authors.affiliation: Department of Optometry & Vision Sciences, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433, Saudi Arabia.
authors.forename: Asma A
authors.initials: AA
authors.lastname: Jawkhab
authors.affiliation: Senior Ophthalmology Consultant, Elite Medical & Surgical Center, Ulaya, P.O Box 65197, Riyadh 11556, Saudi Arabia.
authors.forename: Waleed S
authors.initials: WS
authors.lastname: Al-Tuwairqi
authors.affiliation: School of Optometry & Vision Science and Institute of Health & Biomedical Innovation, Chronic Disease and Aging Domain, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove 5SW36 QLD 4059, Australia.
authors.forename: Uchechukwu L
authors.initials: UL
authors.lastname: Osuagwu
keywords: astigmatism; corneal collagen crosslinking; intrastromal corneal rings; keratoconus; photorefractive keratectomy