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RUSHAD SHROFF, rohit shetty, Arkasubhra Ghosh, natasha pahuja, AARTI AGRAWAL, HARSHA NAGARAJ; Quantitative alterations in nerve morphology differentiate affected and unaffected eyes in Unilateral Keratoconus. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1924. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Unilateral Keratoconus (KC) provides an objective model to study corneal morphology with other risk factors remaining constant. In vivo confocal microscopy (IVCM) has been used to image corneal sub basal nerve plexus (SBNP) changes in KC, however its role in unilateral KC has not been evaluated so far. The aim of this study is to highlight changes in SBNP in unilateral KC and gain insight regarding the role of corneal nerves in pathogenesis, diagnosis and as a marker for disease progression in KC.
In this prospective cross-sectional study, 33 eyes of 33 patients with evidence of keratoconus in one eye (Group 3) were compared with the other normal eye of the same patients (Group 2) and with 30 eyes of healthy age matched controls (Group 1) for the morphology of corneal nerves. Patients with history of contact lens use, ocular surgery, trauma and bilateral KC were excluded from the study. All patients underwent detailed ophthalmic examination followed by topography with Pentacam HR (Oculus Optikgerate GmBH, Wetzlar Germany) and in vivo confocal microscopy (IVCM) using the Rostock Corneal Module/Heidelberg Retina Tomograph II (Heidelberg Engineering GmbH, Dossenheim, Germany). Five images from the center of the cornea obtained with IVCM were analyzed using an automated CCmetrics software version 1.0 (University of Manchester, UK) for the changes in sub-basal plexus of nerves in all eyes. Statistical analyses were performed using Stata version 12.1 (StataCorp, College Station, TX, USA) statistical software.
Intergroup comparison showed statistically significant reduction in the corneal nerve fiber density (CNFD) and length (CNFL) in Group 3 as compared to Group 1 (p<0.001 and p=0.001 respectively) and Group 2 (p=0.01 and p=0.02 respectively). Intragroup analysis in Group 3 revealed that while 18 eyes had decentered cones, 15 had centered cones. Though all the parameters were found to be higher in decentered cones, only the corneal nerve branch density (CNBD) was found to be statistically significant (p<0.01).
This study underscores the importance of IVCM in early diagnosis of keratoconus. It also highlights the importance of alterations in corneal nerve morphology that can be used as an imaging marker for early diagnosis, monitoring of progression and for prognostication of keratoconus.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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