HIGH-RESOLUTION MAGNETIC-RESONANCE-IMAGING EVALUATION OF BLOOD-RETINAL BARRIER INTEGRITY FOLLOWING TRANSSCLERAL DIODE-LASER TREATMENT

Objective: To compare the effects of contact transscleral diode laser treatment and retinal cryotherapy on blood-retinal barrier integrity w ith the use of high-resolution magnetic resonance imaging techniques w ith co ns rant infusion of gadolinium-diethylenetri-aminepentaacetic a cid (Gd-DTPA). Methods: Transscleral diode laser photocoagulation and retinal cryotherapy were used to treat equivalent areas of the inferio r retinal periphery of pigmented rabbits. Magnetic resonance imaging t ime-course studies with measurement of signal enhancements due to Gd-D TPA leakage were conducted 2 and 15 days following treatment. Results: Two days following treatment, cryotherapy-treated eyes exhibited a me an (+/-SD) effective Gd-DTPA permeability coefficient of 4.6+/-0.8X10( -6) cm/s; in comparison, diode laser-treated eyes exhibited 1.6X1.4X10 (-6) cm/s effective permeability. Significant decreases in the effecti ve permeability were also noted 15 days after treatment in both groups . Conclusions: Transscleral contact probe diode laser photocoagulation induces less disruption of the blood-retinal barrier than does conven tional cryotherapy. In addition, the continuous infusion method of Gd- DTPA delivery is a reliable and easily interpretable alternative to th e commonly used bolus injection approach.