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As already shown in healthy subjects, choroidal blood flow is regulated in NDR patients when the ocular perfusion pressure increases. In DR patients, the absence of this control could be due to a failure of the autonomic nervous system, as suggested by pupillometry results.

Background/aims Cerebral malaria (CM) is a disease of high mortality worldwide. It can be associated with malarial retinopathy (MR) resulting from impaired perfusion within the retinal microvasculature. Areas of capillary nonperfusion (CNP) appear white (retinal whitening) on ophthalmoloscopy. In this study, electrophysiological investigations were performed to investigate the physiological consequences of these hypoxic and ischaemic changes. Methods Children admitted with CM were assessed for inclusion in the study. Those with MR underwent further detailed fundus assessment to quantify retinal whitening and were then designated a severity score. Electrophysiological recordings were performed using a miniganzfeldt stimulator with calibration to the International Society for Clinical Electrophysiology of Visual (ISCEV) standards. ERG data were then analysed with respect to presence of MR and also graded disease severity. Results Thirty-one children were recruited with a diagnosis of CM, 20 had MR (group 1), and 11 had absent MR (group 2). Statistical analyses of these two groups showed a significant relationship between reduced single flash cone b wave amplitude (CBWA) and increased severity of retinal whitening/ CNP (Po0.05). Cone and maximal response b : a wave ratios remained 41 in all subjects. Conclusion Retinal whitening/CNP in MR is associated with significant changes in ERG cone b wave function. The relatively high b : a ratio is compatible with the high frequency of MR resolution without sequelae.

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