Semi–Automated Pan–Retinal Photocoagulation in Patients With Diabetic Retinopathy

Abstract

Purpose: : Patients with diabetic retinopathy (DR) requiring pan–retinal photocoagulation (PRP) are typically administered between 1200 and 1500 single laser spots often resulting in physician fatigue and patient discomfort. We present a semi–automated patterned scanning laser retinal photocoagulator that rapidly applies predetermined patterns of lesions, thus greatly improving the comfort, efficiency and precision of the treatment.

Methods: : Eight patients were selected, five with proliferative DR and three with severe pre–proliferative DR. One patient with previous PRP was selected for titration of laser power using the 20 ms pulse duration. A Quadrispheric lens was used with only topical anaesthesia. PRP was applied both conventionally spot by spot (100 ms pulse duration) and using the semi–automated patterned scanning laser photocoagulator (20 ms pulse duration). Patterns of spots were selected from a graphical user interface and positioned on the retina using a joystick. A pattern of 16 spots was used in all the patients. Laser delivery was initiated and could be interrupted at any time by a foot pedal.

Results: : The clinical appearance of individual spots delivered with the semi–automated photocoagulator were similar to conventional spots once adequately titrated. The average power range for conventional delivery (100 ms pulse duration) was 392 mW to 450 mW, and 622 mW to 680 mW for the semi–automated photocoagulator. The average time for conventional delivery of 100 burns was 122s versus 48s for the semi–automated photocoagulator. For the last four patients the pace of application using the patterned photocoagulator was further improved bringing the average time for 100 spots to just 25s. Subjective patient tolerability was very high.

Conclusions: : The features of individual lesions created by the semi–automated photocoagulator were similar to those obtained by conventional delivery. The ability to produce patterns of multiple retinal spots with a single depression of the foot pedal lasting less than one second allowed for rapid application of PRP. This device was able to greatly improve the speed, comfort and precision of retinal photocoagulation.

Keywords: laser • diabetic retinopathy • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials