Vision rehabilitation takes a multidisciplinary effort supported by a variety of subspecialists. Ophthalmologists play a crucial role in identifying patients with low vision and then referring them for rehabilitation therapy. The following seven clinical pearls will help you to successfully “recognize” and “respond” to your low vision patients for optimum treatment.
1. Identify patients who can benefit from vision rehabilitation. Low vision refers to visual impairment that cannot be corrected by standard eyeglasses, medical or surgical treatment. Even early or moderate vision loss causes disability. There is strong evidence to show that rehabilitation improves quality of life.1,2 Refer patients for vision rehabilitation services whenever they demonstrate one or more of the these visual problems resulting in diminished functional ability:
- Acuity of less than 20/40 in the better eye
- Loss of contrast sensitivity
- Scotoma(s)
- Visual field loss
2. Accurately measure visual acuity. Even in the lower ranges of visual acuity, you need precise measurements for several reasons: to appreciate ocular function, to identify eligibility requirements for driving and tax benefits and to recommend devices and interventions. Choose and adjust your measurement method appropriately:
- The commonly used Snellen chart becomes significantly less accurate in the low vision range (<20/100).
- “Count fingers” and “hand movements” are even less accurate.
To extend the measurements into the moderate to low vision range — and get more accurate results — reduce the testing distance. For example, reducing the testing distance from 20 to 10 feet extends the measurement range by a factor of two.
3. Don’t forget about contrast sensitivity. The patient’s ability to resolve objects depends on not only size, but also the contrast or luminance difference between an object and its surrounding area. Loss of contrast can greatly affect his or her ability to perform daily activities. Measuring contrast sensitivity helps provide early detection of disease and can guide recommendations for appropriate rehabilitation. A variety of tests measure contrast at a single or range of spatial frequencies. Examples include the Pelli-Robson contrast sensitivity chart (Haag-Streit AG, Koeniz, Switzerland) and the Colanbrander mixed contrast chart (Precision Vision, La Salle, Ill.).
4. Definitely don’t forget about refracting. To optimize visual performance, be sure to take an accurate refraction. Patients with low vision have a high prevalence of uncorrected refractive error and will often benefit from spectacle correction.3
5. Keep visual field tests simple. Documenting confrontational fields can often provide much of the gross information needed for orientation and mobility. Although formal visual field testing can be useful in diseases that primarily affect the peripheral visual field, it is often of limited use in patients with macular disease and unstable fixation.
6. Educate your patients. Adjusting to vision loss can be a challenging experience.4 Through appropriate patient education, ophthalmologists can play an important role in facilitating that transition. Reinforce the following points with your low vision patients:
- Encourage patients with central field loss that they can effectively use the peripheral retina.
- Be cognizant of visual hallucination symptoms that are suggestive of Charles Bonnet Syndrome; when appropriate, offer reassurance.
- Give all patients who have any level of vision loss the free patient handout created by the Academy’s SmartSight™ Initiative in Vision Rehabilitation. It includes a comprehensive list of low vision resources. Direct patients to the Academy’s EyeSmart® health section on low vision as another useful resource.
7. Develop a support network. Vision rehabilitation often requires a multidisciplinary effort. It is important to develop a network of community resources that can help with your patients’ comprehensive care. Identify regional ophthalmologists and allied health care workers, namely occupational therapists, who specialize in vision rehabilitation. EyeSmart also lists several low vision resources, from providers of large-print checks to national organizations.
Vision loss affects every aspect of one’s daily life, which can leave patients with low vision frustrated and discouraged. Small-group training sessions that teach patients how to cook safely in the kitchen or how to effectively find the accessibility features on a tablet are just some ways rehabilitation can heighten independence, enhance social connectivity and hopefully impart a feeling of greater self-worth. By incorporating vision rehabilitation into your daily practice, you offer this subset of patients an opportunity to achieve an improved quality of life. It also gives you, the clinician, another tool in your armamentarium to manage patients suffering from vision loss.
References
1 Lamoureux EL et al. The effectiveness of low-vision rehabilitation on participation in daily living and quality of life. Invest Ophthalmol Vis Sci. 2007;48:1476–1482.
2 Hassell JB, Lamoureux EL, Keeffe JE. Impact of age related macular degeneration on quality of life. Br J Ophthalmol. 2006;90:593–596.
3 Sunness JS, El Annan J. Improvement of visual acuity by refraction in a low-vision population. Ophthalmology. 2010;117:1442–1446.
4 Zhang X et al. Association between depression and functional vision loss in persons 20 years of age or older in the United States, NHANES 2005-2008. Ophthalmology. 2013;131(5):573–581.
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About the author: Mark D. Bona, MD, is a comprehensive ophthalmologist and cataract surgeon. He completed his residency training at Queen’s University, followed by a traveling fellowship in low vision rehabilitation. Dr. Bona is currently an assistant professor in the department of ophthalmology at Queen’s University. He also serves on the Academy’s Vision Rehabilitation Committee.