Abstract
In retinitis pigmentosa (RP), peripheral visual-field loss starts in early stages, whereas central vision loss occurs in advanced stages. Sensory strabismus gradually occurs in RP. We investigated the relationship between ocular deviation and visual function and explored for sensory strabismus risk factors in 119 consecutive patients with RP at various stages. We assessed ocular deviation at far and near distances, that is the central visual field, using the mean deviation (MD) value and visual acuity (VA), and the residual binocular field area, using Goldmann perimetry (GP), in 33 patients. The horizontal ocular deviation at near distance was >10° in 30% patients and correlated with residual visual function. Although there was no effective cut-off value for central visual function, a cut-off residual GP area of 40 cm2 distinguished patients with a larger from those with a smaller horizontal ocular deviation at far distance (P = 0.04). Our findings suggest that visual function is negatively associated with ocular deviation in patients with RP and that the sensory strabismus risk is relatively high for patients with a binocular visual field <40 cm2. Thus, screening for ocular alignment may be necessary for patients with RP-associated severe vision loss as part of their comprehensive care.
Highlights
Loss or impairment of vision induces sensory strabismus
These patients are expected to exhibit sensory exotropia, it remains unclear whether patients in more advanced stages of retinitis pigmentosa (RP) show greater deviation than those in early stages
This makes RP a unique model compared with other diseases that affect the visual field, such as glaucoma, which rarely cause central without peripheral vision loss
Summary
Loss or impairment of vision induces sensory strabismus. The direction of horizontal strabismus depends on the age at the onset of vision loss. Patients with RP typically lose night vision in adolescence, peripheral vision in young adulthood, and central vision in later life[2] These patients are expected to exhibit sensory exotropia, it remains unclear whether patients in more advanced stages of RP show greater deviation than those in early stages. A considerable area of the peripheral visual field occasionally remains intact, despite the small central visual field, forming the characteristic ring scotoma observed in RP, which enables separate assessments of the effects of peripheral and central visual fields on ocular deviation This makes RP a unique model compared with other diseases that affect the visual field, such as glaucoma, which rarely cause central without peripheral vision loss. The aim of the present study was to investigate the relationship between ocular deviation and visual function and explore the risk factors for sensory strabismus in patients with RP at various stages
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