Association of macular involvement with proliferative retinopathy in Type 2 diabetes

To determine whether documented evidence of pre-existing maculopathy is present in Type 2 diabetic patients who require photocoagulation or vitrectomy for proliferative disease. This is a retrospective case notes review.

The study was performed at Queen's Medical Centre, UK. All patients listed in the laser register and operating theatre register over 5 years (March 1994 to March 1999) who had undergone pan retinal photocoagulation (PRP) for diabetic retinopathy, in one consultant firm, were studied. The medical records of patients who had undergone vitrectomy as their first treatment for proliferative diabetic retinopathy in a vitreo-retinal firm over the 5 years were examined. The proportion of patients with documented maculopathy before development of proliferative retinopathy was determined.

All except 1/134 or 0.7% (95% confidence interval 0.1-4.5%) patients had documentation of macular signs in at least one eye prior to the patient's first session of PRP. Of the remaining 133, 104 (78%) had had focal or grid photocoagulation of the macula. The median time between the documentation of maculopathy before the first PRP treatment session was 16 months (interquartile range 7-36). Fourteen patients had vitrectomy and endolaser performed as the initial treatment for proliferative disease. All patients had documented maculopathy before the onset of proliferative disease.

The results of this study suggest that in Type 2 diabetes, proliferative disease occurs relatively late compared with maculopathy. In such patients, maculopathy is almost invariably present when proliferative disease is detected.