Introduction
Malaria retinopathy is a set of visible changes in the retina which are specific to falciparum
malaria. Studies to date have been mostly limited to comatose African children. Retinal
changes in adults with severe malaria and severely unwell patients without malaria have
been less well studied and the specificity, pathogenesis, diagnostic and prognostic value of
malarial retinopathy in adults are not known.
Methods
A series of observational studies of retinopathy in Bangladesh, India and Malaysia were
done from 2008-2012. The aims were to describe the spectrum of retinal changes in
falciparum and knowlesi malaria in adults, determine their specificity for severe falciparum
malaria, quantify the impact of malaria retinopathy on visual function, understand its
pathogenesis and assess the potential contribution of retinopathy to confirming diagnosis of
malarial coma, predicting prognosis and understanding pathogenesis of cerebral malaria.
Results
495 patients were enrolled and underwent retinal photography (305 with P. falciparum
malaria (112 cerebral, 68 noncerebral severe, 125 uncomplicated), 44 P. knowlesi, 43 sepsis,
41 encephalopathy and 62 healthy). Retinal whitening and white-centred haemorrhages were
common and specific to severe falciparum malaria. Retinopathy was most common and
severe in cerebral (88%) and fatal (91%) falciparum malaria. Moderate-severe retinopathy
was 95% specific for cerebral malaria in comatose patients, and its severity correlated with
depth of coma. Vessel whitening was not seen and papilloedema was rare. In noncerebral
severe falciparum malaria, retinopathy predicted increased likelihood of later development of
coma and death. Retinal findings in Bangladeshi children were similar to those in adults.
Optic nerve sheath diameter was mildly increased and brain swelling minimal on MRI.
Severity of retinopathy correlated with plasma lactate, serum bicarbonate, sequestered
parasite load and red cell stiffness suggesting a central role for microvascular obstruction in
the pathogenesis. Severity of retinal whitening correlated with decreased visual acuity.
Conclusions
Retinal changes seen in severe P. falciparum malaria in Asian adults is similar, but not
identical, to that seen in African children. They have potential to help with diagnosis and
prognosis of Asian adults with severe falciparum malaria. Microvascular obstruction is
prominent in the pathogenesis of retinopathy and coma in adults whereas raised intracranial
pressure is not