Abstract
Purpose :
The presence of malarial retinopathy (MR) confirms the diagnosis of cerebral malaria (CM) and correlates to clinical parameters and disease severity. However, it’s pathogenesis is incompletely understood. For the first time we studied retinal changes of MR using hand-held spectral domain Optical Coherence Tomography (HH-OCT ) and compared findings to fundus photos, fluorescein angiography (FA) and histology to further explore MR and CM pathogenesis.
Methods :
All children presenting with MR positive CM were recruited (N=26). On admission participants were assessed and treated with artemisinin-based combination therapies. They had dilated fundus exam, colour fundus photography (CFP), FA and HH-OCT of the macular and optic nerve. HH-OCT was performed daily during admission and at 1-month where possible.
Results :
Large retinal vessels had abnormal hyper-reflective walls and variable lumina (90% hypo-reflective, 75% hyper-reflective). Those with hyper-reflective walls (no hyper-reflective lumen) had a hyper-reflective ring in the inner retina. Hyper-reflective capillaries were found universally corresponding to the superficial and deep capillary plexi. Hyper-reflexive areas (HRAs) in the middle retina (96%), diffuse whitening with or without hemorrhages (36%), cystoid macula oedema (10%) and undulation of inner/outer retina junction (87%) were seen. Whitening on colour fundus photos corresponded to HRAs in the middle retina. HRAs were hypo-reflective on near infrared images. Histological comparison suggests large vessels with hypo-reflective lumina correspond to vessels with late stage parasitized erythrocytes sequestering around the vessel wall but normal blood in the centre. Hyper-reflective lumina resemble vessels fully filled with parasitized erythrocytes. Vessel changes resolved rapidly after treatment. Moderate to severe hyper-reflective capillaries were present in 61% at admission and reduced to 9% 24hr and 0% 48hr. HRA’s were seen 1-month post admission (83%).
Conclusions :
In MR OCT vessel changes were unique and likely to represent parasitized erythrocytes sequestering on the endothelial wall of large and small vessels. HRAs in the middle retina had similar appearance to paracentral acute middle maculopathy on OCT which has been described in ischemic retinal diseases. OCT changes in MR have the potential to identify children needing more intense treatment and monitor parasite clearing during treatment.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.