RESUMEN
Down syndrome is a common chromosomal anomaly, characterized by specific facial features, eye anomalies with repeated ophthalmic infections. The integrity of the ocular surface is maintained by the tear film. To determine the presence of tear function changes in children with Down syndrome and their relation with the development of ophthalmic diseases. Tear film was evaluated by the ferning test and breakup time [BUT] measurement in 23 patients [46 eyes] confirmed as having Down syndrome by cylogenetic analysis and 20 normal control children [40 eyes] with matched age and sex. There was an alteration in both ferning and BUT tests in children with Down syndrome compared to controls. Abnormal ferning test was found in 28 out of 46 tear samples from the patient's eyes compared to 2 out of 40 normal control eyes. BUT test results showed that the preocular tear film stability was poor in 65.2% of patients' eyes, average in 26.1% and good in only 8.7% of their eyes; while controls had good and average tear film stability each representing 50% of eye's number. These tear function abnormalities may have a role in the frequent infectious pathologies found in the anterior eye segment in patients with Down syndrome which necessitates applying new stringent strategies for ophthalmologic care and management of these patients