Longitudinal Changes of Malarial Retinopathy on Hand-held Optical Coherence Tomography

Abstract

Purpose : Identifying malarial retinopathy (MR) improves the specificity of the clinical diagnosis of cerebral malaria (CM). MR correlates with disease severity and can help predict outcomes. In OCTs at admission we observed abnormal hyper-reflectivity of capillaries and vessels, hyper-reflective areas (HRAs) in the inner retina, cotton wool spots, haemorrhages and cystoid macula oedema. This is the first use of hand-held spectral domain optical coherence tomography (HH-OCT) in CM to investigate longitudinal changes of MR. We compared the thicknesses of retinal layers between CM patients and controls.

Methods : Patients with MR (n= 43) were recruited and underwent dilated fundus examination and colour fundus photography at admission. HH-OCT was performed daily during admission and at 1-month and 1-year post-discharge when possible. Age and gender matched controls (n= 43) had one visit for HH-OCT scans. The thickness of retinal layers was measured using Image J. Longitudinal changes of MR signs on OCTs were compared. Where available, longitudinal MRI scans from 4 patients were also compared with OCTs.

Results : In subsequent examinations after admission, vascular changes and cystoid macula oedema resolved within 48 hours after the start of antimalarial treatment, which is consistent with parasite clearance times. However, HRAs were observed at 1-month follow-up. On admission, patients with CM had thickening in the inner layers at the temporal side of the retina (p= 0.02). At 1-month follow-up, patients with HRAs (n= 18) at admission had significant thinning in the inner layers, especially in the parafoveal temporal side (p= 0.009). In contrast, no difference was found in the CM patient group without HRAs (n= 13). At 1-year follow-up, severe atrophy of inner retinal layers at the temporal parafovea (p< 0.001) was noted in patients who had HRAs at admission (n= 8). Longitudinal MRI scans showed that 3 out of 4 patients with brain atrophy also had significant thinning in the inner retinal layers, while one patient did not have abnormal changes on OCT or MRI.

Conclusions : Our HH-OCT data indicate that OCT changes seen in capillaries and vessels resolve quickly after treatment. However, HRAs are still visible after one month and are associated with retinal atrophy after one year. Retinal atrophy on OCTs may be a potential indicator of visual sequelae, brain atrophy and long-term neurological sequelae.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.