Abstract
Purpose: :
To evaluate the efficacy of phototherapeutic keratectomy PTK, superficial anterior keratectomy and fibrous peeling in decreasing astigmatism related to subepithelial fibrosis.
Methods: :
14 patients (9 females; mean average age 53 years [range 39-79 years]) with irregular astigmatism secondary to an unspecific subepithelial corneal fibrosis were treated in Helsinki University Eye Hospital. All eyes underwent a comprehensive pre- and postoperative ophthalmic examination and videokeratography. All 14 patients had surgery. The epithelium was surgically removed. Five patients were treated with PTK only, 4 patients were treated by a combination of surgical "fibrosis pealing" (FP) and PTK,1 patient had FP combined with amniotic membrane implantation, and 5 patients were treated by anterior keratectomy/FP only. PTKs were performed with a VisX S4 excimer laser to facilitate pealing and/or to ablate scar tissue. All but one patients were subjected to C4 genotyping. The study protocol was approved by the Ethical Review Committee of Helsinki University Eye and Ear Hospital and followed the tenets of the Declaration of Helsinki.
Results: :
The mean preoperative BCVA was on a Log Mar scale 0.16 (Range 0.7-0.00) and the mean preoperative astigmatism was 3.7 D. Postoperative BCVA was 0.11 (0.6 - 0.00) and the mean postoperative astigmatism was decreased to 2.1 D. Preoperative topography showed irregular astigmatism pattern that was improved in all eyes despite the fact that no astigmatic photorefractive correction was performed. Six patients had 2 genes of both C4A and C4B (normal genotype) but 1 of these patients had very low concentration of the C4 B2-protein. Six patients had C4-deficiency of either C4A (1 patient) or C4B (5 patients). One patient had 3 C4A genes and 2 C4B genes.
Conclusions: :
Limbal fibrosis can be treated by peeling of the limbal fibrosis either by PTK or manually. Preoperative irregular astigmatism improved without any astigmatic laser correction and the underlying Bowman was usually intact. C4 deficiencies and/or other immunological deviations may play a role in the pathogenesis.
Keywords: astigmatism • cornea: clinical science • refractive surgery