Abstract
Purpose: :
To assess the long-term visual, refractive, topographic, tomographic and aberrometric results after cross-linking treatment of post-LASIK ectasia.
Methods: :
Twenty-three eyes from 9 female and 14 male patients (mean age 40±7.5 years) with topographically documented progressive post-LASIK ectasia were treated with cross-linking. The standard treatment procedure was used, applying riboflavin 0.1% following epithelial abrasion. The cornea was then irradiated with UVA light. The eyes were monitored for a minimum of 18 months. Best spectacle corrected visual acuity (BSCVA), refraction, topography, cornea thickness and corneal volume, as well as aberrations were documented at regular intervals.
Results: :
At 18 months after cross-linking, mean BSCVA had significantly (p<0.05) improved from 0.47±0.29 to 0.77±0.21 (decimal scale). Mean UCVA and mean spherical equivalent refraction did not show significant differences at 18 months when compared to baseline. Topography maps exhibited markedly reduced steepest points as early as 4 months following treatment, as well as stability of keratometry readings over 6 months and more. Mean central corneal thickness decreased significantly (p<0.05) from 437±45 µm prior to cross-linking to 422±38 µm at 18 months. Similarly, mean thinnest point pachymetry showed a significant decrease from 428±47 µm to 412±44 µm during the follow-up period. Corneal volume also decreased significantly (p<0.05) from a preoperative 57.44±2.58 mm3 to 55.80±3.25 mm3 at 18 months postoperatively. Although mean spherical aberration and mean corneal coma decreased during the 18 months, the differences were not statistically significant when compared with the pre-operative data.
Conclusions: :
Cross-linking appears to be effective in arresting progressive post-LASIK ectasia. The parameters used to monitor the action of cross-linking on keractasia reflect results (although less marked) very similar to those obtained when treating progressive keratoconus. This finding may be explained by the observation that the chronic biomechanical failure process involved in post-LASIK ectasia is similar to that seen in keratoconus.
Keywords: refractive surgery: complications • refractive surgery: LASIK