This study aimed to compare the retinal ischemia changes and the retinal neovascularization regression between the two techniques: pattern scan laser photocoagulation and conventional single spot laser photocoagulation in patients with proliferative diabetic retinopathy.

A prospective clinical trial was done in 146 eyes of 73 patients with proliferative diabetic retinopathy. One eye of each patients was randomly undergone a pattern scan pan retinal photocoagulation and the other eye treated with single argon laser pan retinal photocoagulation and the outcomes were compared between two groups after 6 months include the retinal neovascularization regression and the changes of areas of retinal ischemia, on basis retinal capillary non perfusion in fluorescein angiography.

There was no significant difference in the retinal neovascularization regression of disc and elsewhere in eyes treated with pattern scan or single spot laser. While the areas of the retinal ischemia progression was significantly higher in group treated with pattern scan in comparison to other group.

The areas of retinal ischemia progression were higher after treatment with pattern scan laser compared to single spot laser. Future researches are recommended to find a better modality than the pattern scan to induce regression of the retinal ischemia similar to the single spot laser.