An investigation of saccadic eye movement abnormalities in children with HIV/AIDS on highly active antiretroviral therapy.

Abstract

Introduction: The Human Immuno-deficiency Virus (HIV) and the consequent Acquired Immuno-Deficiency Syndrome (AIDS) have cost the lives of millions of people globally over the past 30 years since the first cases of illness appeared. Due to the overlap in areas in the brain that are damaged by the HIV with those that control saccadic eye movements, screening of eye movement functions in children with HIV/AIDS could thus be a valuable early indicator of a declining neurological and immunological state. Therefore, movement testing through non-invasive means may give the optometrist valuable insight into the developing central nervous system (CNS) in HIV-infected children. Aim: To determine if abnormal saccadic eye movements in children with HIV/AIDS on HAART could be a predictor of the status of their immune system. Methodology: The study population comprised of 128 conveniently selected subjects aged 5 to 14years diagnosed with HIV/AIDS on HAART. This prospective study, used a descriptive design. The two significant biological parameters such as CD4 count and viral load (VL) data of patients were accessed and subjects performed the DEM test, which is a visual-verbal reading speed test, used to detect oculomotor function as well as automaticity skills. The subjects were then classified according to the different „behaviour types‟ as is specified in the DEM test based on their test performances. Statistical Analysis Software (SAS) version 9.2 was used to analyse the data. Results: Nine year olds were the most prevalent comprising of 23% of the sample. Subjects were categorised into three categories of their VL and CD4 count parameters from minimal to severe immunosuppression. Seventy eight percent (78%) of subjects had minimal immunosuppression with CD4 counts ≥500cells/mm3 with a median value of 778.5 cells/mm3. Sixty five percent (65%) of the subjects had undetectable VL (<40 copies/mm3) with the median value of <40 copies/mm3 in the sample. With the DEM test, 93% had vertical and 92% had horizontal times that were outside of the standardised DEM norm. The classification of subjects into behaviour types revealed that 53% were type 3 – automaticity problems, 22% type 4 – oculomotor problems and automaticity problems, 8% type 1 – normal performance and 3% were type 2 – oculomotor dysfunction. Fourteen percent were in the unspecified behaviour type category. The relationship between the VL with behaviour types (p=0.2) and the CD4 count against the behaviour types (p=0.17) were neither statistically nor clinically significant, hence no relationship could be established. Discussion: Since the cognitive functioning in children with HIV/AIDS was moderately affected, the DEM test could be a valuable tool, if not to only detect eye movement problems but to assess the automaticity skills, which shows the impact on their neurodevelopment. It therefore does prove to be worthwhile for optometrists and other health professionals to use the DEM test as part of a battery of neurodevelopmental tests to assess different neurocognitive functions, specifically in children with HIV/AIDS. Recommendation: DEM norms for a South African paediatric population should be established as the characteristics of this population differ from the population of English-speaking American children on which this test was standardised. Conclusion: Immunologic and virologic statuses in children with HIV/AIDS on HAART cannot be predicted from abnormal saccadic eye movements. Performances across all age groups were significantly below the standard DEM norms. Saccadic eye movement abnormalities were the least prevalent and automaticity deficiencies were the most prevalent across the sample with no associations to the CD4 count and viral load.