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Olubayo Umar Kolawole, Nicholas Rinella, Katharina G Foote, Austin Roorda, Jacque L Duncan; High resolution imaging of Preferred Retinal Loci in macular diseases. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4634.
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© ARVO (1962-2015); The Authors (2016-present)
Development of Preferred Retinal Loci (PRL) eccentric to the fovea is an adaptive mechanism that follows irreversible central vision loss due to macular atrophy from different pathologies. This prospective observational study describes the structural and functional characteristics of the PRL using high resolution imaging modalities.
We studied 3 eyes of patients with congenital rubella, Best vitelliform macular dystrophy and age-related macular degeneration with geographic atrophy. Eyes with macular atrophy and visual acuity of 20/40 or better were selected. Ocular evaluation included visual acuity, adaptive optics scanning laser ophthalmoscopy (AOSLO), spectral domain optical coherence tomography (SD-OCT), swept source OCT angiography (OCT-A), fundus autofluorescence (FAF), color fundus photography and fundus guided microperimetry. The fovea was identified as the center of the foveal avascular zone from OCT-A images. We located the PRL in each eye with AOSLO and microperimetry, and correlated anatomic and functional characteristics of the PRL in each patient.
The patients were aged 48, 56 and 87. Visual acuities were 20/20, 20/30 and 20/32, respectively. The PRL was located between 0-0.39 degrees from the edge of the atrophy and 0.58-0.88 degrees from the edge of retained reflective cones. Cones were not visible in confocal AOSLO images of the PRL but split-detector AOSLO images showed evidence of cone inner segments. In all cases more normal-appearing cones were located nearby at greater eccentricities. SD-OCT demonstrated an intact external limiting membrane band with hypo-reflectivity of the inner segment/outer segment band and cone outer segment tips at the PRL in each eye. FAF showed heterogenous signals in the area of PRL. Retinal sensitivities at the PRL were reduced to 19-23 dB, although sensitivities elsewhere in the macula were greater than 25. All 3 patients maintained fixation within 2 degrees of the target between 74-100% of the time.
Stable PRL occurred in areas near the anatomic fovea using cone photoreceptors with reduced cone reflectivity and sensitivity despite more sensitive and more normal-appearing cone mosaics at greater eccentricities. These findings suggest that proximity to the anatomic fovea is more important than structural integrity of cones in mediating spatial vision tasks.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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