A Study to Test the Diagnostic Potential of Brillouin Microscopy for Corneal Ectasia

Inclusion Criteria: Group I includes healthy subjects with normal appearing corneas, normal topography and pachymetry. Group II includes patients diagnosed as having mild, moderate or advanced keratoconus by our ophthalmology expert on the basis of topography and pachymetry. Group III includes healthy subjects who have undergone LASIK surgery in the past 12 months without complications. Inclusion criteria include normal post-operative topography and pachymetry. Group IV includes patients (age 20 - 60) who have undergone LASIK surgery at least 12 months before the study imaging and have been diagnosed with post-LASIK ectasia based on topography, pachymetry and clinical evaluation.Patients diagnosed with keratoconus. Group V- Volunteers to receive PRK surgery This group includes patients who have been diagnosed with myopia and have been scheduled to undergo PRK surgery. Patients with high astigmatism \> 2 diopter, prior ocular surgeries, and those patients taking any ocular medications except seasonal allergy medicine such as ketotifen or artificial tears will be excluded. Group VI-Volunteers to receive LASIK Surgery This group includes myopic patients who are scheduled to receive LASIK surgery. Patients with high astigmatism \> 2 diopter, prior ocular surgeries, and those patients taking any ocular medications except seasonal allergy medicine such as ketotifen and artificial tears will be excluded. Group VII- Patients with Fuch's Endothelial Corneal Dystrophy. This group includes subjects who are diagnosed with Fuch's corneal dystrophy, at early, mild and advanced stages. The inclusion also extends to subjects with, and without keratoconus. But this exclude patients with any other corneal disorders other than keratoconus, and/or history of ophthalmological surgeries that may affect endothelium cell status, e.g. cataract surgeries. Overall Exclusion Criteria for all groups: Volunteers who * Have occludable narrow angles (without a patent peripheral iridotomy) * Monocular subjects * Do not or cannot understand the instructions for the imaging