Profile of horizontal comitant strabismus and outcome of treatment modalities among patients attending strabismus clinic at muhimbili national hospital

Background: Horizontal comitant strabismus is a misalignment of the eyes in which the magnitude of misalignment is the same in all directions of gaze. The global prevalence of horizontal comitant strabismus ranges between 2% to 4%. Untreated horizontal comitant strabismus has visual, social, psychological and mental impact on both children and adults that affect their daily lives. The goals for the treatments are to restore proper ocular alignment, improve visual acuity and restore binocular single vision. The common treatment modalities are spectacle, strabismus surgery and orthoptic exercises. At the strabismus clinic at Muhimbili National Hospital (MNH) several patients attended every week. However, the profile, outcomes of treatment and associated factors have not been studied, which is important for benchmarking and counseling process for practitioners and patients’ choice of different treatment modalities. Aim: To determine the profile of horizontal comitant strabismus and outcome of treatmenmodalities among patients attending strabismus clinic at MNH. Methodology: A prospective cohort study conducted at MNH from May to December 2021. A total of 105 participants were recruited consecutively. An interviewer administered questionnaire was used to collect data on socio-demographic characteristics, medical history, and examination findings of comitant strabismus. Orthoptic assessment was repeated at 6 weeks post treatment. Measurement of post treatment ocular alignment, visual acuity and binocular single vision (stereopsis) were recorded and analyzed by SPSS version 23.0 Results: Majority (73.3%) of participants had esotropia, and among these,67.5% had accommodative esotropia. Patients who were treated with spectacles, strabismus surgery and orthoptic exercise (pencil push-up) were 76.2%, 20.9% and 2.9% respectively. Good ocular alignment was attained in 40.4% of patients with accommodative esotropia treated with spectacles, 70% of patients with congenital horizontal strabismus treated with strabismus surgery and 66.7% of patients with convergency insufficiency treated with orthoptic exercise. Small angle of deviation before spectacle treatment in patients with accommodative esotropia was associated with good outcome. Conclusion: Majority of patients attending strabismus clinic at MNH had horizontal comitant strabismus. Esotropia type of horizontal deviation was common and the overall outcome of treatment by different modalities was good. However, a small angle of deviation was associated with good ocular alignment in patients treated with spectacles. Recommendation: This study recommends early refraction and correction of accommodative esotropia because of observed good outcome. Patients with large angles should be counselled for strabismus surgery early after refractive correction and further studies to assess their treatment outcomes and determinants of outcome should be done.