Comparison of scleral tensile strength after transscleral retinal cryopexy, diathermy, and diode laser photocoagulation
D. P. Han, R. W. Nash, J. R. Blair, W. J. O'Brien and R. R. Medina
Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, USA.
OBJECTIVES: To determine the effect of transscleral diode photocoagulation
on the tensile strength of sclera in an experimental rabbit model and to
compare it with that of transscleral cryotherapy and diathermy. METHODS:
Twenty-four Dutch-belted rabbits received one of the following three
treatment modalities in one eye: (1) transscleral cryotherapy, (2)
transscleral diathermy, or (3) transscleral diode laser photocoagulation.
The opposite eye served as a paired control. Tensile strength measurements
of scleral strips excised from areas of treatment were obtained 6 weeks
later. RESULTS: No statistically significant difference in mean tensile
strength was observed between eyes receiving transscleral cryopexy (n = 7)
or transscleral diode photocoagulation (n = 8) and their corresponding,
paired, control eyes. In contrast, transscleral diathermy reduced mean
scleral tensile strength to 26% of that of the paired control eyes (n = 8,
P = .0001). CONCLUSIONS: In this rabbit model, scleral weakening is
significant following transscleral diathermy while transscleral cryopexy or
transscleral diode photocoagulation produces no significant weakening
relative to paired, untreated controls.
