Outcomes Of Accelerated Corneal Crosslinking In Keratoconus Eyes With And Without Associated Vernal Keratoconjunctivitis- A Comparative Study

The purpose of this study is to compare the outcomes of accelerated corneal cross-linking in eyes with and without vernal keratoconjunctivitis (VKC) in keratoconus patients.

This is a prospective interventional study done in a tertiary eye care center in New Delhi, India on 26 eyes of 19 patients who were diagnosed with keratoconus. The epithelium off- accelerated protocol (15mW/cm² for 6 minutes) was used in all 26 keratoconus eyes which were diagnosed with progressive keratoconus. 

The epithelium off- accelerated protocol (15mW/cm² for 6 minutes) was used in all 26 keratoconus eyes which were diagnosed with progressive keratoconus. Of the total 26 eyes treated, 12 eyes were associated with VKC (group 1) while the other 14 eyes did not have VKC (group 2). Accelerated corneal crosslinking was done using hypo-osmolar riboflavin in eyes that had the thinnest pachymetry of <400µ post epithelial debridement and iso-osmolar riboflavin was used in the rest. The main outcomes measured were changes in visual acuity, thinnest pachymetry, keratometry, progression, complications, and depth of demarcation line on Anterior segment optical coherence tomography at 1 year postoperatively.

Both groups showed no significant change in the Best corrected distant visual acuity, thinnest pachymetry, K_max, or K_steep from the preoperative to postoperative values. The demarcation line was formed at 241.66±16.37µm depth in group 1 and 266.33±37.2µm in group 2 (p-value: 0.04) respectively. No patient in group 1 could tolerate the use of contact lenses despite suboptimal visual acuity with glasses in group 1, whereas 3 patients in group 2 were using RGP contact lenses to improve visual acuity. Post-operative haze was noted in 2/12 and 3/14 eyes in group 1 and group 2 respectively. Complications noted were progression at 1-year post-CXL in one eye and early-onset bacterial keratitis caused by S.epidermidis in one eye in the VKC group.

Though the visual and tomographic outcomes were comparable between eyes with and without VKC undergoing Accelerated CXL for keratoconus, there might be a slightly higher chance of progression and complications like post-CXL keratitis in VKC eyes. The difference in the depth of demarcation line between the 2 groups could be due to an altered immune mechanism, which can occur because of a persisting low-grade inflammation, hampering the interaction of riboflavin molecules with the collagen fibrils. Since it does not seem to significantly affect the visual outcomes or progression rate, it needs further investigation at a molecular level to understand the interactions between the riboflavin molecules and inflammatory mediators in VKC eyes.