Comparison of Epi-ON Corneal Collagen Crosslinking Performed Using an 18-Minute UVA Exposure vs. a 24-Minute UVA Exposure on Eyes With Ectatic Corneal Diseases

The goal of this clinical trial is to study the effects of an experimental (not Food and Drug Administration (FDA)-approved) treatment called corneal crosslinking (CXL) for conditions in which the cornea becomes progressively thin, steep, and misshapen, causing vision to be blurred. CXL is performed by putting riboflavin (vitamin B2) drops onto the eye and then exposing it to ultraviolet (UVA) light at about the same intensity as you get outdoors on a bright, sunny day. It is designed to stop the progression of disease by strengthening the cornea. Study participants will be at least 8 years of age or older and have a diagnosis of keratoconus, ectasia after LASIK, ectasia after PRK, pellucid marginal degeneration, progressive ectasia after previous CXL treatment or forme fruste keratoconus. The main question it aims to answer is: * Does CXL help prevent or slow the progression of someone's corneal condition and vision loss? Participants will: * Attend up to a total of 7 in office visits over the course of 6 months, where several eye and vision tests will be given. Receive CXL (applying riboflavin (Vitamin B2 eye drops) to the eye, then exposing the eye to ultraviolet (UV-A) light). * There will be two groups of participants. One group will receive the UVA treatment for 18 minutes and the other group will receive the UVA treatment for 24 minutes.