Purpose: Keratoconus is a disorder that results in visual loss from increased corneal high-order aberrations and irregular astigmatism and reduces quality of life. The primary treatment for progressive keratoconus is crosslinking (CXL). Recently, it has been suggested that oxygen enhances the type II photodynamic reaction of CXL that is oxygen dependent. Our study investigated the effect of increased oxygen availability in epithelium-on CXL on visual acuity and corneal curvature. Methods: We searched PubMed, EMBASE, Medline, Web of Science, and Scopus databases on November 3, 2021. We included studies that reported increased oxygen availability during CXL in patients with keratoconus published within the last 10 years. A meta-analysis on the primary outcomes, maximum keratometry, and corrected distance visual acuity, was conducted. Results: The search yielded 108 publications which were screened and assessed for eligibility. Six studies were included in the systematic review and 5 studies were included in our meta-analysis of the outcomes of increased oxygen availability in accelerated CXL. The meta-analysis on data after 6 months of follow-up found a significant decrease in mean maximum keratometry of 1.2 diopter (95% confidence interval: 0.2–2.3; P=0.02) and an improvement in mean corrected distance visual acuity by 0.08 logMAR (95% confidence interval, 0.02–0.13; P=0.01). There were no serious adverse events reported. Conclusions: Increasing oxygen during epithelium-on CXL improved visual acuity and produced corneal flattening without any serious adverse events in patients with keratoconus. The demarcation line depth was significantly higher with oxygen compared to the control group. Further data are required with a control group and long-term follow-up across a range of CXL protocols for implementation into standard clinical practice.

: This report describes the spontaneous extrusion from between the eyelids of a presumed conjunctivolith in a patient with resolving severe herpes zoster ophthalmicus. A 57-year-old man presented for ophthalmologic assessment and management due to severe left herpes zoster ophthalmicus. At one subsequent ophthalmologic assessment, a conjunctivolith spontaneously egressed the lateral commissure of the OS when the lateral fornix was inspected. The conjunctivolith was retrieved from the floor of the consulting room. Electron microscopic analysis and energy dispersive spectroscopy was undertaken to determine its composition. Scanning electron microscopy showed that the conjunctivolith was composed of carbon, calcium, and oxygen. Transmission electron microscopy diagnosed Herpes virus within the conjunctivolith. Conjunctivoliths, or possible lacrimal gland stones, are a very rare phenomenon, and their etiology is currently unclear. In this case, there was likely to have been an association between herpes zoster ophthalmicus and the conjunctivolith.