Therapeutic use of the 193-nm excimer laser in corneal pathologies

Abstract

PTK with the 193-nm excimer laser is a safe and effective treatment for many superficial diseases of the cornea.

Clinical Outcome and Recurrence of Epithelial Basement Membrane Dystrophy after Phototherapeutic Keratectomy

“…The improvement in BSCVA after PTK noted in this study has also been reported by others treating EBMD patients. [5][6][7]9,13,14,16,24 No patient required a second treatment during the entire follow-up period (the single eye excluded from this study While maintenance or improvement of BSCVA is one clinical goal of PTK treatment in EBMD, prevention of recurrent erosive episodes is in many cases equally important. In 5 of 52 (9.6%) of PTK treated eyes, at least one erosive event was noted postoperatively, but erosions were mild or infrequent and did not warrant re-operation.…”

“…The original indication for operation in this study was RCE in only 50% of the cases, whereas in a number of earlier reports, the majority of EBMD patients had RCE symptoms. [7][8][9][10][12][13][14][15][16][17] In one report, however, 67% of 30 EBMD eyes treated by PTK did not have RCE, 6 and in another series of 74 EBMD eyes, 82% were without RCE. 25 It is important to recognize that EBMD is a condition that can lead to visual disturbances, RCE, or both.…”

“…A broad definition of recurrence was adopted to include both morphologic and clinical types, but recurrences were considered to be clinically significant only when patients presented with symptoms of RCE or disturbed vision at the latest follow-up. We could only find a few reports where both clinical and morphologic (slitlamp) measures were considered in the assessment of recurrence 6,8,13,14 and no reports using IVCM to asses recurrence. Dinh et al defined the criteria for significant recurrence as the presence of RCE or significant visual loss combined with slit-lamp evidence of recurrent dystrophy.…”

“…We noted a mean hyperopic shift of 0.49 diopters after PTK treatment, but could not detect any relationship between ablation depth in this study and refractive change, possibly because the majority of ablations were performed with a single standard 15m depth. Several studies in EBMD patients with shallower ablation depths either noted no change 9,13,14,16 or a slight hyperopic shift 6,10 after PTK. Although in our patient group a small overall hyperopic shift was noted, PTK did not result in refractive errors requiring correction in initially emmetropic patients, as was reported in one case in an earlier study.…”

“…In recent years, excimer laser phototherapeutic keratectomy (PTK) has become an increasingly popular surgical option for the treatment of EBMD, due to successful resolution of symptoms documented in a number of studies. [4][5][6][7][8][9][10][11][12][13][14] While the majority of PTK treatments are successful, postoperative recurrence of symptoms has been reported, [6][7][8][9][10][15][16][17] and the reasons for recurrence remain unclear. In a recent study examining a small number of EBMD patients longitudinally, we proposed that dystrophic recurrence may be related to the depth of laser ablation by PTK and the postoperative presence of Bowman's layer (BL).…”