1. Vergence and accommodation responses in the control of intermittent exotropia
- Author
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Universitat Politècnica de Catalunya. Departament d'Òptica i Optometria, Universitat Politècnica de Catalunya. GREO - Grup de Recerca en Enginyeria Òptica, Mestre Ferrer, Clara, Neupane, Sonisha, Manh, Vivian, Tarczy Hornoch, Kristina, Candy, Rowan, Universitat Politècnica de Catalunya. Departament d'Òptica i Optometria, Universitat Politècnica de Catalunya. GREO - Grup de Recerca en Enginyeria Òptica, Mestre Ferrer, Clara, Neupane, Sonisha, Manh, Vivian, Tarczy Hornoch, Kristina, and Candy, Rowan
- Abstract
Purpose Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia to achieve eye alignment. This study examined the relationship between simultaneously recorded accommodation and vergence responses in children and young adults with a range of types of IXT while aligned and deviated. Methods Responses of 29 participants with IXT (4–31¿years) and 24 age-matched controls were recorded using simultaneous eye-tracking and eccentric photorefraction while they watched a movie in binocular or monocular viewing at varying viewing distances. Gradient response AC/A ratios and fusional vergence ranges were also assessed. Eight participants had divergence or pseudo-divergence excess type IXT, 5 had convergence insufficiency and 16 had basic IXT. Results Control and IXT participants accommodated similarly both in monocular and binocular-aligned conditions to visual targets at 80 and 33¿cm. When deviated in binocular viewing, most participants with IXT exhibited changes in accommodation <0.5D relative to alignment. Gradient response AC/A ratios were similar for control [0.56 MA/D (IQR: 0.51 MA/D)] and IXT participants [0.42 MA/D (0.54 MA/D); p =¿0.60]. IXT participants showed larger vergence to accommodation ratios with changes from distance to near fixation [1.19 MA/D (1.45 MA/D)] than control participants [0.78 MA/D (0.60 MA/D); p =¿0.02], especially among IXT participants with divergence or pseudo-divergence excess. Participants with IXT exhibited typical fusional divergence ranges beyond their dissociated position [8.86 ¿ (7.10 ¿)] and typical fusional convergence ranges from alignment [18 ¿ (15.75 ¿)]. Conclusions This study suggests that control of IXT is typically neither driven by accommodative convergence alone nor associated with over-accommodation secondary to fusional convergence efforts. These simultaneous measurements confirmed that proximal vergence contribu, This study was supported by National Institutes of Health grant R01 EY014460 (TRC), P30 EY019008 to Indiana University, and an unrestricted grant to the University of Washington Department of Ophthalmology from Research to Prevent Blindness (New York, NY)., Peer Reviewed, Postprint (published version)
- Published
- 2023