Abstract
Purpose :
We performed a prospective, interventional clinical study on patients with proliferative diabetic retinopathy (PDR) in order to investigate changes in retinal oximetry before and three months after panretinal photocoagulation (PRP) and to correlate this to PDR-activity.
Methods :
Thirty-nine eyes from 34 patients with diagnosed PDR were included. We performed wide-field fluorescein angiography (WFA) (Optomap; Optos PLC., Dunfermline, Scotland, UK) and retinal oximetry (Oxymap model T1; Oxymap, software version 2.4.2, Reykjavik, Iceland) at baseline and three months after PRP by a navigated laser (NAVILAS®; OD-OS GmbH, Berlin, Germany). At follow-up, WFA was used to evaluate PDR activity and patients were categorized into two groups: progression (Group 1, n=10) or stability/regression of PDR (Group 2, n=29).
Retinal oximetry measurements were performed on optic disc centered images using the in-built software that automatically marked the vessels; one larger arteriole and venule in each quadrant were identified for measurements, pre-specified protocol.
Results :
At baseline, mean age and duration of diabetes were 54.8± years and 21.7± years, respectively, and 72% were male. HbA1c was 67±mmol/mol, and the mean blood pressure was 152/84mmHg. Retinal arterial and venous saturation was 96.7% and 67.4%, respectively.
Patients in Group 1 and 2 did not differ in baseline retinal arterial and venous oxygen saturation, number of laser spots delivered, total laser energy delivered, or change in retinal arterial oxygen saturation after PRP (-1.2% vs. -0.4%, p=0.92).
In contrast, as compared to baseline, the improvement in retinal vein oxygen saturation was significantly different between the groups (+2.7% for Group 1 vs. -3.5% for Group 2, p=0.02).
In a multivariable logistic regression analysis, adjusted for the mentioned variables, the change in retinal vein oxygen saturation between baseline and follow-up independently predicted PDR-progression (OR 1.31 per 1% increment in retinal venous oxygen saturation between baseline and follow-up, 95% CI 1.03-1.61, p=0.03).
Conclusions :
Lack of reduction in retinal venous oxygen saturation after PRP was independently associated with PDR-activity. This might reflect absence in reduction in vascular endothelial growth factor (VEGF) and could be a potential non-invasive marker of disease activity.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.