Abstract
Purpose:
To determine the incidence and probability of Pars Plana Vitrectomy (PPV) in insulin-dependent and non-insulin-dependent diabetic patients within 2 years of receiving Pan Retinal Photocoagulation (PRP).
Methods:
Patient records from Vanderbilt Eye Institute from 2000-2008 with any diabetic retinopathy billing codes receiving PRP were reviewed. Patients were excluded if they had prior PRP for other primary diagnoses, such as retinal vein occlusions or rubeotic glaucoma. Patients were also excluded from the study if they had had prior PRP, destructive cryotherapy treatment, or PPV. Additional eyes were excluded if they had insufficient information.
Results:
374 eyes were included for analysis. We found statistically significant differences in the probability of receiving a PPV within two years following initial PRP based upon reason for initial PRP, insulin dependence, and age. Compared to patients receiving initial PRP for proliferative diabetic retinopathy (PDR) alone, patients receiving PRP for PDR and vitreous hemorrhage (VH) had 2.78 times the likelihood (p<.0001) of undergoing a PPV within 2 years. Similarly, a patient receiving PRP for PDR and other pathologies, defined as iris neovascularization; VH and traction; fibrosis and VH; or fibrosis, the likelihood of PPV within two years was 3.54 times (p<.0001) greater than PDR alone. Eyes from insulin-dependent patients were 1.74 times as likely (p=.0021) to undergo PPV within 2 years than non-insulin dependent diabetics following initial PRP. Age at initial PRP was negatively correlated with receiving a PPV, as every one-year increase in age was associated with a 3% decrease in the likelihood of undergoing PPV within 2 years (p=0.0002). The percentage of eyes receiving PPV within 1 and 2 years following PRP for PDR alone was 12.2% (95% CI: 7.97,18.4) and 21.1% (95% CI: 15.1, 29.1); for VH and PDR was 32.8% (95% CI: 25.2, 42.0) and 44.3% (95% CI: 35.8, 53.7); and for patients with PDR and other pathologies 44.5% (95% CI: 27.5, 65.9) and 58.3% (95% CI: 39.6, 78.1).
Conclusions:
Patients who received PRP for PDR as well as VH, traction, fibrosis, or VH and fibrosis were more likely to undergo PPV within 1 and 2 years following initial PRP. Insulin-dependent diabetes was positively associated with PPV, while age was negatively associated.
Keywords: 762 vitreoretinal surgery •
499 diabetic retinopathy •
464 clinical (human) or epidemiologic studies: risk factor assessment