Assessment of quality and adequacy of panretinal photocoagulation in proliferative diabetic retinopathy using ultra-widefield imaging.

PURPOSE:To assess the characteristics of completed panretinal photocoagulation (PRP), using ultra-widefield imaging in proliferative diabetic retinopathy. METHODS:Quantitative assessment of ultra-widefield imaging images of 133 patients with proliferative diabetic retinopathy with completed PRP was made using ImageJ software. The parameters assessed included distance of laser spots from the optic disk, foveal center, superior and inferior arcades, and extent of the maximum width of laser. Areas assessed were total area of the image, area of the inner limit within which laser spots are restricted, minimum areas of unlasered patches, total area lasered, and ideal area to be covered by PRP. RESULTS:Two hundred one images were assessed for the final analysis. The mean distance of laser spots was 4.2 ± 2.4 mm from the optic disk (nasal) and 6.6 ± 2.5 mm from the foveal center (temporal). The mean distance of laser spots from the superior arcade vessel was 3.2 ± 1.9 mm and 6.2 ± 4.4 mm from the inferior arcade. The mean area of the retina that should have been ideally lasered was found to be 900 ± 267 mm 2 , and the actual area lasered was found to be 681 ± 254.4 mm 2 . CONCLUSION:Approximately one-quarter area of the retina continues to remain ischemic because of the lack of inadequate coverage of PRP. Further longitudinal studies are recommended, using ultra-widefield imaging to objectively assess the adequacy of PRP and its role in modulating the course of progression of the retinopathy.