[Phototherapeutic keratectomy for recurrent corneal erosion of various epithelial origins: influence of depth of ablation on pachymetry and refraction].

BACKGROUND

Phototherapeutic keratectomy (PTK) is an established treatment method for patients suffering from either genetic corneal dystrophy or recurrent corneal erosion (RCE) without underlying basement membrane dystrophy, often caused by trauma.

OBJECTIVE

This study aimed to describe the changes in manifest subjective refraction and pachymetry after PTK treatment in patients suffering from epithelial basement membrane dystrophy (EBMD) and traumatic or atraumatic RCE without underlying EBMD.

MATERIAL AND

METHODS

This was a retrospective, single-center study performed at the Department of Ophthalmology of the Ludwig-Maximilians University (Munich). Patient data were retrospective collected using the smart-eye database of the Department of Ophthalmology including diagnostic data from an autorefractometer and from the Pentacam HR. All laser treatments were performed with an ablation depth of 10 μm for EBMD patients and 6 μm for RCE patients without EBMD.

RESULTS

Both collectives showed a decrease in pachymetry larger than the calculated ablation depths after a follow-up interval of 126 days (95% CI 104-147 days). While the EBMD collective receiving an ablation of 10 μm showed a decrease of 25.8 μm (N = 74; 95% CI 21.2-30.3; p < 0.001), the non-EBMD collective receiving an ablation of 6 μm showed a decrease of 12.3 μm (N = 44, 95% CI 7.0-17.7; p < 0.001). Both, total corneal refractive power (TCRP) as well as spherical equivalent (SE) offered no significant change in preoperative and postoperative comparison for the EBMD collective. On the other hand, patients without underlying EBMD showed a significant myopic decrease in SE of 0.4 dpt (±0.7 dpt SD, p < 0.05). The mean follow-up interval was 126 days (95% CI 104-147 days).

CONCLUSION

PTK treatment offers an effective method for patients suffering from either EBMD dystrophy or RCE syndrome without underlying EBMD. The final ablation based on pachymetry at the apex can be estimated at 2.3 to 2.6 times higher compared to the original ablation depth. The reasons for this are on the one hand the laser ablation itself and the influence of the reactive wound healing of the corneal epithelium.