Abstract
Purpose: :
Application of hundreds of single laser burns during panretinal photocoagulation is time consuming and tedious for the patient and physician. We present the design and evaluate the performance of a semi–automated patterned scanning laser retinal photocoagulator to improve the comfort, efficiency and precision of treatment by rapid application of predetermined patterns of lesions, rather than single spots.
Methods: :
Each pattern of spots was selected from a graphical user interface and positioned on the retina with an aiming beam by means of a joystick. Laser delivery was initiated and could be interrupted at any time by depressing a foot pedal. The powers required to create burns of approximately equal ophthalmoscopic appearance using pulse durations of 10, 20, 50 and 100ms were determined in pigmented rabbits. Histopathologic verification of burn comparability was obtained.
Results: :
By employing pulse durations as short as 10 ms, multiple spots were delivered in the time required for a single conventional 100 ms pulse. Complex patterns of 36–49 burns could by created in under one second. The laser power required to produce clinically visible retinal lesions decreased from 240 to 50 mW with pulse durations increasing from 10 to 100 ms. Burns created with shorter pulses (10–20 ms) demonstrated slightly greater uniformity and required less total energy than those with longer pulses (50–100 ms). The histological appearance of ophthalmoscopically similar lesions produced by different combinations of pulse duration and power was comparable.
Conclusions: :
The operation and histologic features of individual lesions created by a patterned scanning laser system were similar to those obtained with conventional retinal lasers, but in addition, the former were also able to produce patterns of multiple retinal burns with a single depression of the foot pedal lasting less than one second. Rapid application of multiple lesions using short pulse durations and scanning can greatly improve the speed, comfort and precision of retinal photocoagulation.
Keywords: retina • diabetic retinopathy