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New Software, “OKN-dot Test” for Visual Rehabilitation for Eye Patients

New Software, “OKN-dot Test” for Visual Rehabilitation for Eye Patients

New Software, “OKN-dot Test” for Visual Rehabilitation for Eye Patients

Gloria Wu, MD1; Agastya Gupta2; Vidhya Gunasekara, MD3; Kimberly Pham, BA4; Don Byongdo Kim, BA4; Victor Chen, BA5.

1University of California, San Francisco School of Medicine; 2Saratoga High School; 3Ophthalmology, Aravind Eye Hospital; 4University of California, Berkeley; 5University of California, San Diego

Background:

Ophthalmologists, optometrists and low vision specialists are interested in visual rehabilitation for patients with low vision. Specifically, patients with diabetic retinopathy, glaucoma, age related macular degeneration, and stroke patients have need for visual training or low vision training.

According to the World Health Organization, approximately 285 million adults and children are visually impaired. In the US, 4.2 million adults have vision impairment according to the National Eye Institute. For patients older than 70 who require assistance, the burden of low vision is third, behind arthritis and heart disease.

Low vision techniques are based on using larger images or optotypes to improve reading ability. The basis of much of this training is to train the patient to view objects eccentrically, making full use of the undiseased part of the retina or macula. While extra-macular retina function is less efficient than macular function, this may be the only option for certain patients. Currently, such techniques include the use of computer enhanced image enlargement or telescopes. Telescopic glasses are hard to use and require training, and large screen closed circuit televisions are costly, ranging from $500 to $1000. New devices, such as Google Glass, could magnify reading, but it is unclear if this new device can be adapted for elderly, low vision patients.

In the 1980’s, during the research phase of the Scanning Laser Ophthalmoscope (SLO), age related macular degeneration patients had their central scotomata documented and images were projected to the healthy, non-diseased retina.1,2,3 This was an early attempt to use SLO technology for vision training and eccentric viewing. However the cost of the SLO is prohibitive for individual home use.

The Bates method of using accommodation techniques to improve vision was discovered in the 1920’s by Dr. William Bates, an ophthalmologist who believed that various eye exercises could improve vision.4 His pupil, Margaret Darst Corbett, continued his work in Southern California from the 1940’s to the 1960’s. The most famous Bates pupil, Aldous Huxley, used these techniques. However, the Bates method, though well known, is controversial in its efficacy.5

Patients with central scotomata are faced with the challenge of maximizing their vision capabilities in their activities of daily living, such as reading or using the computer. Thus, these patients must learn to fixate eccentric to the fovea. Therefore, vision training techniques would be useful for patients with loss of central vision, yet there are no universally accepted techniques for vision training among ophthalmologists.

Optokinetic nystagmus has been used to test vision in nonverbal children and adults by eliciting a primitive reflex involving the oculomotor system and the frontal lobe. Eye movement and vision are stimulated. Optokinetic nystagmus has been used extensively to test vision in newborn infants.

The optokinetic reflex is a result of a combination of naturally elicited saccade and smooth pursuit eye movements when presented with alternating black and white one-inch stripes.This reflex develops at 6 months of age and allows the eye to follow objects in motion while the head remains stationary, such as watching telephone poles on the side of the highway as one travels by in a moving car. These images project to the pontine nuclei in the pons, which are vital for motor function. The pontine nuclei are part of the cerebellar flocculus circuitry, which is wired to the vestibular complex. The vestibular complex innervates the muscles in the eyes, which allow for the smooth pursuit movements associated with the optokinetic reflex. 6,7

First Person Shooter (FPS) software technology involves the targeting system of the frontal lobe, as well.  The interactive software game allows the test taker (TT) to respond to the random temporal and spatial presentation of colored dots (blue, green, red) by clicking a mouse. The score changes if the TT clicks the dots at a faster or slower rate.  The game can be repeated and the TT can increase his score and there is a sense of self reward when the TT sees the score at the end of the 14 second game.  We combined the method of using OKN as a oculomotor “warmup” exercise with target fixation in FPS to create a vision education tool that uses targeted fixation.

The software program was coded in Java using the Eclipse compiler, utilizing the javax.swing graphics interface; images were created in the GNU Image Manipulation Program.  Then, the program was uploaded onto a laptop. During use, the software presents alternating black and white one inch stripes, which is then followed by an FPS software game of colored dots that move, disappear and reappear and can be “hit” with a mouse click to enter a score within 14 second period of the test.

Purpose:

To assess the use of new software, “OKN-Dot Test”* as a tool for visual rehabilitation in ophthalmology patients.

Methods:

Testing Methods:

Volunteers were recruited in a Retina Clinic in San Jose, California, and informed consent was obtained from the patients and control group.

Each test taker was tested with the Snellen visual acuity chart before initiating the software program. The test taker (TT) was seated in a quiet area with one of the authors present. Explanation and timing of the test was standard. The OKN stripes were presented to the test taker (TT) for 15 sec, with both eyes open. The Dot test was presented to each eye individually (the fellow eye was patched) for 5 consecutive trials. Each dot test trial lasted 14 sec.  The test generated a score of the greatest number of dots clicked by the test taker within 14 seconds.  At the end of the software presentation, repeat Snellen visual acuity was taken. Visual Acuity ranged from 20/15 to 20/50.

Measurement Methods:

Each letter of the 5 letter line of the Snellen Chart was given 0.2 score, so if all 5 letters were attained, the score would be 1.0. Best visual acuity was pinhole visual acuity, if the test subject did not reach 20/15.

Results:

okn_01

Figure 1: New software, OKN-dot test screenshots

okn_02

Figure 2: The average test scores between controls and participants

okn_03

Figure 3: Changes in visual acuity from pre and post-test. One letter = 0.2

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Figure 4: The averages of first and fifth scores of patients.

Conclusion:

This small study suggests that patients with mild visual impairment had a positive change in visual acuity after the” OKN-Dot Test” versus our Control Group. Patients improved their test score between test 1 and test 5 of the dot part of the “OKN-Dot Test” suggesting that fixation improved with the FPS software technology. Target fixation with the built-in reward system of scores may increase motivation in patients who need or want vision training. Further testing will be needed with a larger sample size and longer follow-up whereby the patients practice the test daily or weekly over 3 to 6 months and then have their vision re-checked periodically. The next patient group to be studied would be those with poor visual acuity in the 20/80 to 20/100 range. This small study suggests that gaming technology of First Person Shooter may be useful for vision training.

References:

1. Nilsson UL, Frennesson C, Nilsson SEG. Patients with AMD and a large absolute central scotoma can be trained successfully to use eccentric viewing, as demonstrated in a scanning laser ophthalmoscope. Vision Research. 2003;43(16):1777–1787.

2. Fletcher DC, Schuchard RA, Livingstone CL, et al. Scanning laser ophthalmoscope macular perimetry and applications for low vision rehabilitation clinicians. Ophthalmol Clin N Am. 1994;7:257–265.

3. Katsumi O, Timberlake GT, Hirose T, Van de Velde FJ, Sakaue H. Recording pattern reversal visual evoked response with the scanning laser ophthalmoscope. Acta Ophthalmologica. 1989;67(3):243-248.

4. Bates, William H. The Cure of Imperfect Sight by Treatment Without Glasses. New York, New York: Henry Holt and Company LLC; 1971.

5. Duke-Elder, Stuart. Aldous Huxley on Vision. British Medical Journal. May 22, 1943; 1(4298) 635-636. http://europepmc.org/articles/PMC2282772. Accessed June 18, 2014.

6. Swenson, Rand S. Review of Clinical and Functional Neuroscience. Dartmouth Medical School. 2006. http://www.dartmouth.edu/~rswenson/NeuroSci/index.html. Accessed June 18, 2014.

7. Walsh and Hoyt’s Clinical Neuro-Ophthalmology. Sixth Edition online. Philadelphia, Pennsylvania: Lippincott Williams and Wilkins; 2005: 83-151, 1133-1176. http://content.lib.utah.edu/cdm/ref/collection/ehsl-wht/id/76. Accessed June 18,2014

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