Posters

Assessment of postoperative haze after deep transepithelial photorefractive keratectomy (trans-PRK) without mitomycin using a new ablation algorithm to smoothen the stromal wound bed

Poster Details

First Author: F.Gilardoni SWITZERLAND

Co Author(s):    E. Torres-Netto   R. Abrishamchi   N. Hafezi   F. Hafezi           

Abstract Details

Purpose:

The use of topical Mitomycin C applied intraoperatively to the stromal bed has been considered mandatory in order to prevent corneal haze after photorefractive keratectomy (PRK), especially in deeper ablations. There is experimental evidence that a recently introduced new ablation algorithm may lower postoperative inflammation and thus, stromal haze formation. In the present study, we have assessed corneal haze in patients that underwent transepithelial-PRK with a stromal ablation of more than 80 µm, without the use of mitomycin C.

Setting:

The study was conducted in the ELZA Institute in Dietikon, Switzerland, in collaboration with the Laboratory for Ocular Cell Biology, Center for Applied Biotechnology and Molecular Medicine at the University of Zurich (Zurich, Switzerland).

Methods:

Data was retrospectively collected at the ELZA Institute in Dietikon, Switzerland. We included all patients that underwent transepithelial photorefractive keratectomy (trans-PRK) without mitomycin C after February 2016. Inclusion criteria were myopic astigmatism and ablation of more than 80 µm of stromal bed. Patients with a history of corneal disease or ocular surgery were excluded. Corrected distance-visual acuity (CDVA), refraction and haze were assessed preoperatively, and at 1 month and 3 months after surgery. Haze was assessed both using a standardized grading system at the slit lamp and the densitometry analysis of Scheimpflug images (Pentacam HR, Oculus Instruments, Wetzlar, Germany).

Results:

We evaluated 21 eyes from 12 patients. Mean stromal ablation depth was 106.14 µm. Slit lamp corneal haze analysis showed clinically insignificant haze at 1 month (grade ≤0.5 in all eyes) and 3 months (2 eyes grade 1, 19 eyes grade ≤0.5) after surgery. Corneal densitometry showed a significant decrease in the anterior 120 µm (p=0.001) and no significant changes in the intermediate layer and the posterior 60 µm. Only the central 2 mm of the intermediate layer showed a significant increase in densitometry (p=0.006). All patients received fluorometholone eye drops for 12 weeks after complete closure of the epithelium.

Conclusions:

We show that deep stromal ablation of more than 100 µm without the use of mitomacin C does not result in clinically relevant haze. The observed decrease in corneal densitometry in the anterior layers and the increase in of the central intermediate layer are in line with previously reported analyses in more superficial ablations. The present study may indicate that in a central European setting and with a novel excimer laser ablation profile, the use of mitomycin C in deep ablation PRK may not be essential.

Financial Disclosure:

None