Combined PRK and CXL in keratoconus
Reviewed by Inderpaul S Sian

This study aimed to investigate the results after photorefractive keratectomy (PRK) followed immediately by standard 30-minute corneal cross-linking (CXL) for keratoconus. This retrospective study included 26 eyes of 16 patients with keratoconus. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (SE) and cylinder, apical keratometry, corneal higher order aberrations (HOAs), and corneal haze were evaluated. Mean follow-up was 32±8 months (range: 19 to 50 months) and mean patient age was 31±5 years (range: 24 to 40 years). Mean UDVA improved significantly from 0.80±0.39 to 0.32±0.36 logMAR after surgery (p<.001), but the mean CDVA worsened significantly from 0.07±0.09 to 0.15±0.14 logMAR after surgery (p=.006). Thirteen eyes (50%) lost at least one line of CDVA, three eyes (12%) lost two lines, and four eyes (15%) lost three lines. SE, cylinder and apical keratometry decreased significantly. Corneal haze grade 1 was found in 15 eyes (57.7%), grade 2 in six eyes (23.1%), and grade 3 in one eye (3.8%). A significant correlation was seen between postoperative CDVA loss and corneal haze (p=.001) and history of atopy (p<.01), but not with corneal HOA change. Despite an improvement in UDVA and topographic values, the loss of CDVA, explained by postoperative haze, demonstrates that this procedure should be approached with caution, may not be as safe as initially thought, especially in patients with atopy and can cause severe visual acuity loss. When CXL was associated with PRK, the findings of this study showed that despite an improvement in UDVA, manifest refraction and topographic values with a substantial loss of CDVA was observed associated with an increased incidence of corneal haze and surface irregularity. Further studies with greater sample sizes and longer follow-up periods are required to evaluate safety, efficacy and predictability of combined PRK and CXL.

Haze and visual acuity loss after sequential photorefractive keratectomy and corneal cross-linking for keratoconus.
Moraes RLB, Ghanem RC, Ghanem VC, Santhiago MR.
JOURNAL OF REFRACTIVE SURGERY
2019;35(2):109-14.