In vivo Adaptive Optics Retinal Imaging in Ischaemic Diabetic Maculopathy

Abstract

Purpose: To study the structure-function correlates using adaptive optics (AO) retinal imaging and microperimetry in patients who have ischaemic maculopathy secondary to diabetes.

Methods: AO retinal imaging of 9 eyes (8 patients), who had previously been diagnosed with an ischaemic macula following fundus flourescein angiography (FFA), was acquired with an AO camera (rtx1, Imagine Eyes, Orsay, France). AO images were taken at >1 year following FFA on 5 eyes and at 6 months following FFA in 4 eyes, respectively. The AO in-vivo findings were correlated anatomically and functionally with spectral-domain optical coherence tomography (SD-OCT) scans, FFA and microperimetry (MP).

Results: AO imaging showed pockets of white-out, with disruption and loss of signal from photoreceptors (PR) outer segments in the >1 year group. A characteristic “empty honeycombs” appearance was also noted close to areas of previous laser treatment. In the 6 month group, though there was ischaemia documented on FFA, PR were still identifiable, though there was apparent clumping and poor definition of the cone signals on AO. Corresponding SD-OCT at these regions showed minimal disruption of inner segment (IS)-ellipsoid band of the photoreceptor cell layer unlike in the long-standing group where the integrity of IS-ellipsoid band was greatly disrupted. MP at the corresponding site with significant PR loss showed complete loss or significantly impaired retinal sensitivity, whereas in the other group the retinal sensitivity was minimally reduced.

Conclusions: The AO imaging has enabled us to demonstrate the loss of PR outer segments in the group of patients with long-standing (> 1year) ischaemic macula changes, whilst at the same time demonstrating relative preservation of PR outer segments at 6 months. These in vivo findings of loss and survival of PR outer segments, depending on duration of ischaemia provide an indication of the potential therapeutic window to reverse capillary closure and ischaemia and potentially rescue photoreceptors using new stem cell techniques.

Keywords: 499 diabetic retinopathy • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 648 photoreceptors