205a
CW-DIODE LASER THERMOKERATOPLASTY - 18 MONTHS PILOTSTUDY
B. Jean, M. Derse, T. Bende, T. Oltrup, B. Wannke, H.-J. Thiel
Objective: Evaluation of predictability, safety and complications 18 months after cw-Diode laser thermokeratoplasty (LTK).
Patients and Methods: Since summer 1996 LTKs were performed in 20 eyes of 20 patients using a cw-diode laser (Rodenstock LTK 1.9, Rodenstock Instr., Ottobrunn). For the correction of astigmatism, two pairs coagulation cones in each of the flat hemimeridians of the cornea were applied using the contact probe technique. For the correction of hyperopia, two concentric rings (8 coagulation spots each) were used in the same technique. A total energy of 720 mJ per spot was applied. Optical zone diameter was varied between 6 and 8 mm depending on the intended amount of correction.
Results: Astigmatism corrections: The preoperatively existing astigmatism of 4.0 ±
1.0 D (avg. ± 1 SD) was reduced to 1.45 ± 1.35 D after an intended overcorrection, stabilizing after 135 days on the average. One patient (age < 25 years) showed complete regression due to shallow coagulations ( approx.60-70% of corneal thickness). Hyperopia correction: A total of 6 patients was treated. In younger patients a hyperopia reduction of up to 3.75 D has been achieved. In those patients older than 40 years the reduction ofhyperopia was approximately 1 D more.Conclusion: The results of the pilot study show that the cw-diode laser LTK is a predictable procedure for the correction of astigmatism and hyperopia (superior to current excimer laser applications) when sufficient coagulation depth (> 90 %) is achieved. The results are verified in a european multicenter study that has been started yet.
Div. of Experimental Ophthalmic Surgery (DEOS), Univ. Eye Hospital Tuebingen Derendinger Str. 41, D-72072 Tuebingen