Preferred Retinal Locus in Age-related Macular Degeneration

OCT SLO

Project Overview

Intact central vision is critical for activities of daily living including reading, driving, face recognition, etc. When people lose their central vision due to retinal disease, genetic mutation, etc., many of these activities are greatly impacted. The visual system compensates for the central vision loss by adopting an eccentric preferred location in the retina called the preferred retinal locus (PRL). This spontaneously developed locus has not been well explored in the past, and understanding the retinal structure and function at this location could help us better rehabilitate individuals with central vision loss, such as those with macular degeneration.

Age-related macular degeneration (AMD) can impact many day-to-day activities like face recognition, reading, driving, etc.1 Patients with AMD may have to use a non-foveal eccentric location, the preferred retinal locus (PRL) for fixation and other visual tasks. The PRL can vary between tasks, but in general has been documented to be just outside the degenerated retinal area and hence may not be in a region of normal retina 2. There may also be local functional changes at the PRL.3 Visual rehabilitation, including eccentric viewing training and training in the use of low vision devices, has been the mainstay of low vision management of patients with AMD.4

Understanding the PRL assumes significance as it can potentially lead to better rehabilitation as well as provide crucial insights about the disease process of AMD. Optical Coherence Tomography (OCT) is an imaging modality that is analogous to ultra sound scan and uses light to obtain a high-resolution image of the retina. Micro-perimetry is a potent tool to investigate local retinal sensitivity, and is different from conventional testing in its capability to track a retinal region of interest and compensate for fixational eye movements. The latter ensures reliable presentation of visual stimuli at the intended retinal locations.5, 6

In this study, we will utilize a commercially available instrument, OPKOS OCT/SLO 7, to study in detail the retinal region corresponding to the reading PRL in subjects with AMD. Specifically, we propose to probe the retinal sensitivity in the local regions at the reading PRL and assess the integrity of the outer retinal layers in the same region. Understanding both the retinal function and structure will provide a comprehensive picture of the retinal regions used for reading, which may help us understand how the reading PRL develops in relation to the AMD disease process.

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Team Members

Arun Kumar Krishnan, PhD
Postdoctoral Research Fellow Susana Chung, OD, PhD, FAAO
ERI Affiliate Scientist

References & Publications

1. The Eye Diseases Prevalence Research Group (2004). Prevalence of age related macular degeneration in the United States. Archives of Opthalmology.122; 564-72.

2. Paulus T. V. M de Jong. (2006). Age-Related Macular Degeneration. The New England Journal of Medicine. 355; 14; 1474-85.

3. Arunkumar Krishnan and Harold Bedell. (2014). Sensitivity around the word-fixation PRL in subjects with bilateral central field loss. Optometry & Vision Science. 91: E-abstract 145066.

4. Schuchard RA et al. (1999). Characteristics of AMD patients with low vision receiving visual rehabilitation. Journal of Rehabilitation Research and Development. 36(4); 294-302.

5. Tolentino MJ et al. (1994) Visual field defects in early macular degeneration. Vision Research. 34(3); 409-13.

6. Midena E et al. (2007). Micro-perimetry and fundus auto fluorescence in patients with early age-related macular degeneration. British Journal of Ophthalmology. 91; 1499-1503.

7. https://www.youtube.com/watch?v=v3vqcIgikSQ (‘The Optos OCT SLO Imaging System for Retinal Analysis’ Video retrieved on: 7/21/2016)