Visual Fixation and Function in Central Vision Loss

Running Participant on Eye Tracker

Project Overview

Intact central vision is critical for activities of daily living including reading, driving, face recognition, etc.1 When people lose their central vision due to retinal disease, genetic mutation, etc., many of these activities are greatly impacted. Several changes in visual system ensues central vision loss including a) Use of an eccentric preferred location in the retina for performing various visual tasks2, and b) Increase in the amplitude of involuntary fixational eye movements.3

Age-related macular degeneration (AMD), which results in irreversible central vision loss, 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 for fixation and other visual tasks. Fixational eye movements in people with central vision loss is primarily affected in that the amplitude of these tiny involuntary eye movements is larger than that in people with normal vision3. Because fixation stability (FS) has become an outcome measure in rehabilitation and intervention for patients with AMD, it is important to ensure that the quantification of FS is accurate. Several factors such as recording duration4,5, recording instrument and its characteristics (e.g.: sampling rate) can hamper proper recording and interpretation of FS.

In this study, we will utilize several commercially available instruments, OPKOS OCT/SLO and eye trackers (EyeLink II and 1000+) to study the FS in both typically sighted and visually impaired subjects. Specifically, we propose to determine the influence of duration and sampling rate on the FS. Such understanding of the FS may help us better interpret and compare the measurements.

More information on this study can be found here (PDF file, opens in new window).

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INCLUSION: diagnosed with Macular Degeneration/Central Vision Loss in both eyes. EXCLUSION: head tremors, Nystagmus (shaky eye movements), inability to vocalize reading, and best corrected vision in the better eye worse than 20/400.

Arun Kumar Krishnan, PhD
Bosma Enterprises Postdoctoral Research Fellow
Arun.Krishnan@envisionus.com
316-440-1524
Participant Consent Form (PDF File, opens in new window)

Team Members

Arun Kumar Krishnan, PhD
Bosma Enterprises Postdoctoral Research Fellow Susana Chung, OD, PhD, FAAO
ERI Affiliate Scientist Mehmet N. Ağaoğlu, PhD
Postdoctoral Scholar, University of California, Berkeley

References & Publications

  1. The Eye Diseases Prevalence Research Group (2004). Causes and prevalence of visual impairment among adults in the United States. Archives of Opthalmology.122(4); 477-485.
  2. Crossland MD, Engel SA and Legge GE. (2011). The preferred retinal locus in macular disease: toward a consensus definition. Retina. 31(10); 2109-2114.
  3. Kumar G and Chung ST. (2014). Characteristics of fixational eye movements in people with macular disease. Invest Ophthalmol Vis Sci. 55(8); 5125-5133.
  4. Sansbury RV, Skavenski AA, Haddad GM and Steinman RM. (1973). Normal fixation of eccentric targets. J Optom Soc Am. 63(5); 612-614.
  5. Tarita-Nistor L, Gill I, Gonzalez EG and Steinbach MJ (2017). Fixation Stability Recording: How Long for Eyes with Central Vision Loss? Optom Vis Sci. 94(3); 311-316.