OCT in Diagnosis of Irregular Corneas

Inclusion Criteria: GROUP A: * Keratoconus: 1. CDVA ≥ 20/25 in the better eye; and both of the following in the worse eye 2. Topography characteristic of keratoconus or pellucid marginal degeneration * Contact lens-related corneal warpage: 1. Contact lens use; and 2. Topography irregularities * Dry eye: 1. Symptoms of dry eye documented by Ocular Surface Disease Index (OSDI) questionnaire score ≥ 30; and 2. Topography irregularities 3. Presence of punctate epithelial erosion on exam with surface staining 4. Aqueous deficiency or evaporative dry eye * Epithelial basement membrane dystrophy (EBMD): 1. Negative corneal fluorescein staining; and 2. Corneal opacities; and 3. Topography irregularities * Stromal addition or subtraction: 1. Scars; or 2. Salzmann's degeneration; or 3. Stromal dystrophies; or 4. Complication (visual complaints) after LASIK or photorefractive keratectomy (PRK) * Stromal distortion: 1. Radial keratectomy (RK); or 2. Corneal transplants. * Normal controls: 1. Healthy eyes with no previous eye procedures/surgeries. GROUP B: Participants will be selected from the keratoconus population in Group A based on topography findings. GROUP C: Participants will be selected from the stromal addition/subtraction and stromal distortion populations of Group A if they have vision primarily limited by scars, dystrophy, or high astigmatism that could benefit from PTK. Exclusion Criteria (all groups): * Inability to give informed consent. * Inability to maintain fixation for OCT imaging. * Inability to commit to required study visits. * Eyes with concurrent cataract, retinal disease, glaucoma, or other eye conditions that may limit the visual outcome after surgery. * Previous corneal surgeries if considered as a keratoconus participant. * Pregnancy or breastfeeding.