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Near Point of Convergence in Intermittent Exotropia

Sanjeev Bhattarai, Kishor Sapkota, Jeevan Kumar Shrestha, Ramchandra Lamichhane and Douk Hoon Kim

Introduction: Intermittent exotropia (IXT) is the most common type of exo-deviation. Patients with IXT can maintain binocular single vision (BSV) and the duration of binocular disruption depends upon its severity and the status of convergence mechanism. Those patients with good near point of convergence (NPC) can use BSV most of the time. Aim: To determine NPC in patients with IXT. Materials and methods: It was a hospital based cross-sectional study conducted in BP Koirala Lions Center of Ophthalmic Studies over a period of one year starting from Janaury 2009. All patients with IXT and age ranging from 5-35 yrs were included in this study. Complete ophthalmologic examination was done including measurement of NPC with RAF rule and magnitude of deviation with Synaptophore. Results: Out of 115 patients, majority of patients (58%) were students and headache was found to be the most common complaint (65%). Two thirds of patients had IXT of 10-25 PD at near while half of patients had IXT of < 10 PD at distance. Mean NPC was 13.27 ± 3.46 cm. Two-thirds of the patients had NPC of 10 cm or more. NPC was not associated with age and gender of patients (p ≥ 0.05). 74% of patients had normal near point of accommodation (NPA) according to their age. Four fifths of patients had normal visual acuity in both eyes. Almost all (98%) of patients had positive stereopsis at near but at distance, 77% of patients had positive stereopsis. Conclusion: NPC is poor in two thirds of IXT patients. NPA and visual acuity was normal in majority of cases. Stereoacuity was found better at near than at distance.