Mohammad-Reza Sedaghat1, Hamed Momeni-Moghaddam2,3, Javad Heravian3,4, Michael W Belin5, Renato Ambrósio6,7, Tayebe Gheysari-Alishahi2, Seyyed Hossein Ghavami1. 1. Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. 2. Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. 3. Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran. 4. Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran. 5. Department of Ophthalmology and Vision Science, University of Arizona, Tucson, AZ. 6. Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; and. 7. Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.
Abstract
PURPOSE: To investigate the changes in corneal backward scattering using Scheimpflug tomography (densitometry) 6 months after intrastromal corneal ring segments (Keraring) implant for keratoconus and to correlate with clinical results. METHODS: Along with standard ophthalmic examination, Scheimpflug tomography using Pentacam HR was performed to document corneal densitometry and corneal shape. A densitometry map was displayed using grayscale units (GSUs) ranging from 0 to 100 (minimum to maximum light scattering) in 4 concentric annuluses: central 2-, 2- to 6-, 6- to 10-, 10- to 12-, and total 12-mm corneal diameter and at 3 different depths: anterior 120 μm, posterior 60 μm, middle (varying accordingly to the total thickness), and total thickness. RESULTS: The changes in mean corneal densitometry values for anterior, central, and posterior layers were 3.82 ± 3.13, 2.70 ± 1.78, and 1.68 ± 1.52 GSU, respectively, and for annuluses of 0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm were 2.96 ± 2.60, 4.53 ± 2.28, 2.09 ± 1.74, and 0.45 ± 3.93 GSU, respectively. The mean values increased for all corneal layers (P < 0.05), except in the peripheral 10- to 12-mm annulus (P> 0.05). The highest increase was in the annulus 2 to 6 mm of the anterior layer (5.72 ± 3.70 GSU). Changes in the mean densitometry showed a significant correlation with the mean of average keratometry changes only for the front corneal surface and changes in the Q-values for both corneal surfaces in the 2- to 6-mm annulus for all layers. CONCLUSIONS: Significant increase in the corneal densitometry mainly in the anterior 2- to 6-mm annulus of the cornea is associated with the position of the ring segment implant. More studies are needed to elucidate the relevance of such findings.
PURPOSE: To investigate the changes in corneal backward scattering using Scheimpflug tomography (densitometry) 6 months after intrastromal corneal ring segments (Keraring) implant for keratoconus and to correlate with clinical results. METHODS: Along with standard ophthalmic examination, Scheimpflug tomography using Pentacam HR was performed to document corneal densitometry and corneal shape. A densitometry map was displayed using grayscale units (GSUs) ranging from 0 to 100 (minimum to maximum light scattering) in 4 concentric annuluses: central 2-, 2- to 6-, 6- to 10-, 10- to 12-, and total 12-mm corneal diameter and at 3 different depths: anterior 120 μm, posterior 60 μm, middle (varying accordingly to the total thickness), and total thickness. RESULTS: The changes in mean corneal densitometry values for anterior, central, and posterior layers were 3.82 ± 3.13, 2.70 ± 1.78, and 1.68 ± 1.52 GSU, respectively, and for annuluses of 0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm were 2.96 ± 2.60, 4.53 ± 2.28, 2.09 ± 1.74, and 0.45 ± 3.93 GSU, respectively. The mean values increased for all corneal layers (P < 0.05), except in the peripheral 10- to 12-mm annulus (P> 0.05). The highest increase was in the annulus 2 to 6 mm of the anterior layer (5.72 ± 3.70 GSU). Changes in the mean densitometry showed a significant correlation with the mean of average keratometry changes only for the front corneal surface and changes in the Q-values for both corneal surfaces in the 2- to 6-mm annulus for all layers. CONCLUSIONS: Significant increase in the corneal densitometry mainly in the anterior 2- to 6-mm annulus of the cornea is associated with the position of the ring segment implant. More studies are needed to elucidate the relevance of such findings.