Abstract
Purpose: :
To describe two patients with Leber’s Hereditary Optic Neuropathy and no organic macular disease that use nonfoveal retina for fixation due to a central scotoma.
Methods: :
Two patients, ages 28 (patient 1) and 52 (patient 2), with sudden vision loss attributed to genetically confirmed Leber’s Hereditary Optic Neuropathy (11778 and 14484) were evaluated. Visual acuity was followed over several weeks and visual field testing was performed with both the Humphrey VFA (24-2) and Rodenstock scanning laser ophthalmoscope (SLO). Macular imaging was performed with Optical Coherence Tomography (OCT) and/or fluorescein angiography (FA) and the SLO was used to identify the PRL nature and location.
Results: :
Patient 1’s visual acuity 3 weeks after visual decline was 20/200 OD and OS. Patient 2’s visual acuity was measured at 20/300 OD and 20/200 8 months after visual decline. In the absence of macular disease, both patients exhibited a central dense scotoma of approximately 8 degrees diameter which encompassed the fovea. Each used a well-defined eccentric retinal area (PRL) for fixation with binocular retinal correspondence. One patient had anatomically superiorly located PRLs OU while the other had the PRL nasal OD and temporal OS relative to the non-functioning fovea. The PRL locations were consistent and repeatable on SLO evaluation. The PRL location relative to the scotoma was consistent with Humphrey VFA findings of fixation relative to visual field loss and no peripheral field losses were noted. Fundus photo of patient 1 showed small, cupless, elevated discs with indistinct borders. Patient 2’s fundus photo showed normal appearing optic disc without edema or atrophy. OCT of the macula demonstrated an undisturbed IS/OS junction and normal foveal depression. Fluorescein angiography showed no leakage or staining in the macula. There was evidence of microangiopathy at the discs.
Conclusions: :
Central dense scotomas and non-foveal eccentric PRLs are well known in association with macular disease but not in optic neuropathy. We observed 2 patients with isolated LHON with normal retinal structural characteristics who also demonstrated central scotomas and eccentric PRLs. This unexpected finding has significance for the rehabilitation interventions required to maximize use of residual vision for people with this permanent impairment.
Keywords: visual fields • optic nerve