Functional assessment of retinal neovascularizations

Diabetic retinopathy (DR) results in vascular damage and impaired neuronal function. Proliferative DR (PDR) is characterized by hypoxia and subsequent neovascularization, yet the resulting impact of these events on retinal function is unknown.

Currently, the only therapeutic intervention in PDR is the delay of neovascularization, achieved by photocoagulation to decrease oxygen consumption. However, it has not been determined, whether these newly formed vessels have only adverse effects or whether neovascularizations are sufficient to perfuse the inner retina and thus prevent the loss of neuroretinal function.

Ang2(-/-) mice and a mouse model of retinopathy of prematurity (ROP) were used for central and peripheral neovascularization, respectively. The impact on neuronal function was assessed by multifocal electroretinography (mfERG) at different time-points.

Throughout the observation period, no reduction of photoreceptor function (A-wave) in the neovascularized areas was detectedable in Ang2(-/-) mice compared to controls (P10: 2.01 ± 0.93 vs. 1.67 ± 0.61; P25: 1.95 ± 1.2 vs. 1.64 ± 0.88; P60: 1.84 ± 0.69 vs. 1.34 ± 0.64; [µV/field]; n.s.). The inner retina showed no sign of functional deficits (B-wave) compared to the control group (P10: 2.08 ± 0.59 vs. 2.42 ± 0.97; P25: 2.09 ± 0.72 vs. 2.04 ± 0.58; P60: 2.65 ± 0.63 vs. 2.26 ± 0.26; [µV/field]; n.s.).

Likewise, no signs of neurofunctional impairment was detected in the ROP model at P60 (A-wave: 1.44 ± 0.41 vs. 1.34 ± 0.64; B-wave: 2.20 ± 0.33 vs. 2.26 ± 0.26; [µV/field]; n.s.).

Taken together, these results indicate, that central neovascularization enables sufficient perfusion by the newly formed vessels, despite their instability, resulting in protection of retinal function. Further in-depth analysis of possible neurovascular alterations in the angiogenic front are currently carried out.

Supported by DDG.