Spatial changes of central field loss in diabetic retinopathy after laser.

PURPOSE

To explore the spatial distribution of central visual field loss in untreated proliferative diabetic retinopathy (PDR) and to quantify the effect of medium-pulse Optos-guided 20-millisecond Pascal laser treatment on the central field.

METHODS

Visual field data (Swedish Interactive Threshold Algorithm 24-2) from 99 eyes (66 patients) with treatment-naive PDR were used to train a self-organizing map (SOM) that classified the defects into nine patterns. Twenty-eight eyes of 23 patients treated with 20-millisecond Pascal retinal laser photocoagulation underwent Optos widefield fundus fluorescein angiography (WF-FFA) at baseline and 3 months after treatment. Postlaser changes in SOM patterns and global indices were analyzed. Visual field defect changes (Total Deviation [TD]) with eccentricity and extent of initial loss were analyzed. Grading of WF-FFA after laser was undertaken by two masked retina specialists.

RESULTS

At baseline, 44.4% of PDR eyes showed early visual field loss patterns (1 to 3), with 23.2% classified into the advanced patterns (7 to 9). Mild SOM patterns had more superior hemifield field defects, whereas advanced patterns involved both superior and inferior hemifield field loss. After laser, a significant shift to early SOM patterns were observed (p = 0.02), as well as improvement of Mean Deviation and Pattern Standard Deviation (p = 0.003 and p = 0.06, respectively). Improvement of TD was commonly observed in test locations of 0 to 10, 10 to 20, and 20 to 30 degrees. Greater improvement was observed with deeper baseline TD (p < 0.001). Masked WF-FFA image grading showed 78.6% PDR regression.

CONCLUSIONS

The SOM method is a promising technique to classify and monitor over time PDR-associated visual field defects. Medium-pulse Optos-guided 20-millisecond Pascal laser treatment improved the spatial patterns and global parameters of central field defects.