Rohit Shetty1, Rudy M M A Nuijts2, Maneck Nicholson1, Koushik Sargod1, Chaitra Jayadev1, Himabindu Veluri1, Abhijit Sinha Roy3. 1. Cornea and Refractive Surgery Division, Narayana Nethralaya, Bangalore, India. 2. Cornea Clinic, Department of Ophthalmology, Maastricht University Medical Center, Maastricht, Netherlands. 3. Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya, Bangalore, India. Electronic address: asroy27@yahoo.com.
Abstract
PURPOSE: To evaluate the effect of keratoconus cone location on the change in refractive outcomes, corneal aberrations, and biomechanics after combined topography-guided photorefractive keratectomy (PRK) and collagen cross-linking (CXL). DESIGN: Prospective, comparative case series. METHODS: Topography-guided PRK was performed followed by accelerated CXL using riboflavin A and enhanced-intensity (30 mW/cm(2)) ultraviolet light. Outcome parameters including uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (BDVA), corneal tomography and biomechanics (corneal hysteresis [CH] and corneal resistance factor [CRF]), and corneal wavefront aberrations were assessed before and a year after the procedure. Eyes were subdivided into 2 groups preoperatively for statistical analysis: Group 1, cone located within the central 2-mm zone; and Group 2, cone located outside the central 2-mm zone. RESULTS: UDVA, BDVA, sphere, cylinder, and simulated keratometry improved after treatment in both groups (P < .05). However, BDVA improved more in Group 1 than in Group 2 (P = .04) and the other variables were not affected by cone location. A few corneal wavefront Zernike aberrations changed after treatment (P < .05) but none were affected by cone location (P > .05). CH and CRF increased after treatment in both groups (P > .05). Interestingly, the increases in CH and CRF were greater in Group 2 than in Group 1 (P > .05). CONCLUSIONS: Cone location appeared to impact only visual acuity and biomechanics after the combined procedure. The greater increase in CH and CRF in Group 2 may indicate differences in the ablation profile and variability in CXL outcomes and requires further study.
PURPOSE: To evaluate the effect of keratoconus cone location on the change in refractive outcomes, corneal aberrations, and biomechanics after combined topography-guided photorefractive keratectomy (PRK) and collagen cross-linking (CXL). DESIGN: Prospective, comparative case series. METHODS: Topography-guided PRK was performed followed by accelerated CXL using riboflavin A and enhanced-intensity (30 mW/cm(2)) ultraviolet light. Outcome parameters including uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (BDVA), corneal tomography and biomechanics (corneal hysteresis [CH] and corneal resistance factor [CRF]), and corneal wavefront aberrations were assessed before and a year after the procedure. Eyes were subdivided into 2 groups preoperatively for statistical analysis: Group 1, cone located within the central 2-mm zone; and Group 2, cone located outside the central 2-mm zone. RESULTS:UDVA, BDVA, sphere, cylinder, and simulated keratometry improved after treatment in both groups (P < .05). However, BDVA improved more in Group 1 than in Group 2 (P = .04) and the other variables were not affected by cone location. A few corneal wavefront Zernike aberrations changed after treatment (P < .05) but none were affected by cone location (P > .05). CH and CRF increased after treatment in both groups (P > .05). Interestingly, the increases in CH and CRF were greater in Group 2 than in Group 1 (P > .05). CONCLUSIONS: Cone location appeared to impact only visual acuity and biomechanics after the combined procedure. The greater increase in CH and CRF in Group 2 may indicate differences in the ablation profile and variability in CXL outcomes and requires further study.
Authors: L Fernández-Vega-Cueto; V Romano; R Zaldivar; C H Gordillo; F Aiello; D Madrid-Costa; J F Alfonso Journal: J Ophthalmol Date: 2017-12-18 Impact factor: 1.909
Authors: Vardhaman P Kankariya; Ankita B Dube; Michael A Grentzelos; George A Kontadakis; Vasilios F Diakonis; Myrsini Petrelli; George D Kymionis Journal: Indian J Ophthalmol Date: 2020-12 Impact factor: 1.848