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A. L. Rees, G. S. Rubin; Can AMD Patients Read Text Quicker at Their PRL Than Other Peripheral Retinal Areas?. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3064.
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© ARVO (1962-2015); The Authors (2016-present)
Most patients with age related macular degeneration (AMD) and dense central scotomas in both eyes adopt a preferred retinal locus (PRL) for eccentric viewing. The majority of patients place their PRL to the left of their scotoma in visual field space. However a PRL position in inferior visual space should be optimal as it provides a larger uninterrupted visual span for reading and mobility. The aim of this study was to compare reading speed (RS) at the PRL to RS in the "optimal" location.
10 normal vision subjects and 15 AMD patients were recruited. All AMD patients had dense central scotomas in both eyes and were tested on a scanning laser ophthalmoscope to identify the PRL location in their better eye. The subjects read text presented against a white background one word at a time by the rapid serial visual presentation (RSVP) technique. Word duration was increased or decreased using a staircase algorithm. Final word duration was converted to words per minute. For subjects with normal vision, text was presented along eight equally spaced radii at 2 eccentricities (5 and 10 degs). For AMD patients the text was presented at the patient’s PRL, and at the theoretically optimal location in the lower visual field. Fixation was monitored with an eyetracker.
14 of 15 AMD patients read quicker at their PRL than the optimal location, but 12 of 15 read slower at their PRL than the age similar normals at the equivalent eccentricity. The difference was 4x for patients with PRLs closest to the fovea and declined with eccentricity. 3 patients with PRLs greater than 9 degs read faster than age similar normals at the equivalent eccentricity.
In AMD patients RS was better at the PRL than at the theoretically optimal location. We cannot distinguish whether the PRL develops at the area of best RS or if it improves at the PRL through practise. AMD patients read significantly slower than normals when the PRL is less than 9 deg from the fovea but faster than normals for PRL locations further from the fovea. These data suggest that factors other than PRL eccentricity may contribute to slow reading performance in AMD patients.
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