Aim: To determine the ocular findings in Lassa fever patients as well as their usefulness in making diagnosis and predicting mortality in Lassa fever patients.
Methods: A study of patients who presented in the accident and emergency unit, the children emergency room, male and female medical wards, pediatrics and Lassa Fever wards of the Irrua Specialist Teaching Hospital over a six-month period. Consecutive Lassa RT-PCR positive cases and febrile Lassa RT-PCR negative controls were recruited. A structured questionnaire was filled by the survey team for each patient. General and ocular examinations were carried out by the researcher after donning level-4 safety gear, using Snellen’s chart, pen-torch, non-contact Keeler Pulsair tonometer, portable hand held slit lamp bio-microscope, fluorescein strips where indicated, indirect ophthalmoscopy with fully dilated pupils and fundus photography with the Volk Pictor fundus camera.
Results: A total of 29 patients comprising of 19 males (65.5%) and 10 females (34.5%) who tested positive for Lassa RT-PCR were seen over the period. The study showed that more than 80% of the patients had normal presenting visual acuity for distance (6/6 – 6/12). Nearly a quarter (24.1%) had significant adnexal abnormalities such as eye discharge, ptosis, lid oedema and tearing. More than 50% of the cases had diffuse conjunctival injection. Sub conjunctival haemorrhage (3.4%) and circumcorneal injection (3.4%) were also seen. Keratic precipitates were seen on the cornea of 2 cases (6.9%) and bilateral dendritic corneal ulcers in one case (3.4%). Significant retinal findings included flame shaped haemorrhages and retinal oedema. More than 65% of the cases had flame shaped haemorrhages at the macula. One case (3.4%) had a punched out chorio-retinal scar with hyperpigmented borders, pale center and satellite lesions presumed to be an old toxoplasmosis scar. The intra-ocular pressures were less than 10mmHg in 15 patients (79.0%).
Conclusion: Significant ocular findings in Lassa fever patients were IOP less than 10mmHg, discharge, ptosis, tearing, lid oedema, dendritic corneal ulcer, keratic precipitates, retinal haemorrhages, retinal oedema, orange vessels, silver wiring of vessels and flame shaped haemorrhages at the macula. Intra ocular pressure less than 10mmHg, retinal haemorrhages, macular haemorrhages, keratic precipitates were specific in predicting Lassa fever in the study. None of the ocular findings was statistically significant in predicting mortality.