By Mark W. Roark, OD, FAAO
Published via Optometric Management MacuHealth Nutritional Insights Newsletter
As vision experts, we must be prepared for patients who complain of visual problems not explained by uncorrected refractive error or ocular pathology. I have found the following four steps to be effective in helping these challenging patients.
Step 1: Understand How Your Patients Really See
Eyecare practitioners perform many tests to properly evaluate and diagnose any problems with a patient’s visual system. Visual acuity, aberrometry, color discrimination, visual field analysis, and dark adaptation all provide valuable information, but we often overlook a key measure of visual performance: contrast sensitivity (CS).
CS describes the ability of the visual system to identify the edges of an object and to differentiate it from its background. In my practice, I routinely assess patients’ monocular CS thresholds (best measured at a 20/100 target size1), and it is hard to overstate the insight gained regarding the visual impact of many ocular conditions.
Though non-specific, CS strongly correlates with real-world visual function.2 I find that patients who describe excessive visual glare or light sensitivity often show reduced CS which, in the absence of another explanation, may be due to suboptimal ocular nutrition.3 These "20/20 unhappy" patients are common in practice and they may be frustrated if no diagnosis or treatment plan is offered.
Step 2: Evaluate the Latest Research in Nutrition and Visual Performance
Recent nutritional research has advanced our knowledge. Supplementation with the three dietary macular carotenoids—lutein (L), meso-zeaxanthin (MZ), and zeaxanthin (Z)—can improve CS at 20/100 in patients free of ocular disease and with normal visual acuity.4 This many not be surprising, as the typical Western diet is deficient in these critical nutrients needed for optimal visual function, reduction of intracellular oxidative stress, and absorption of high-energy blue light.3,5-6
Step 3: Consider Results in Real Patients
The table below illustrates the effective use of this strategy in a sampling of actual patients from my practice. All had apparently healthy eyes with 20/20 vision but significant visual symptoms as noted prior to consistent supplementation with L, MZ, and Z for more than six months. A gain of one or more lines (≥0.1 log unit) in CS threshold is considered clinically significant.3,7-8
Step 4: Implement a New 20/20 Approach in 2020
As our knowledge and experience increase, we must be willing to implement new strategies that improve patient care. An informed approach will incorporate a more accurate assessment of vision through CStesting. It will also include confidently prescribing specific nutritional products that enhance a patient’s visual function, and the cases above show the results obtained using MacuHealth with LMZ.3
Implementing the above protocol has been greatly rewarding in my practice for these now “20/20 happy” patients. Integrating these steps into your own practice can make 2020 your patients’ best vision year yet.
Reference(s): Owsley C, Sloane ME. Contrast sensitivity, acuity, and the perception of “real-world” targets. Br. J. Ophthalmol. 1987;71:791–796National Research Council (US) Committee on Vision. Emergent Techniques for Assessment of Visual Performance. Available at: https://www.ncbi.nlm.nih.gov/books/NBK219042/ (last accessed Jan. 13, 2020)Nolan JM, Power R, Stringham J, et al. Enrichment of macular pigment enhances contrast sensitivity in subjects free of retinal disease: Central Retinal Enrichment Supplementation Trials report 1. Invest Ophthalmol Vis Sci. 2016;57(7):3429-3439Johnson EJ, Maras JE, Rasmussen HM, Tucker KL. Intake of lutein and zeaxanthin differ with age, sex, and ethnicity. J. Am. Diet. Assoc. 2010, 110, 1357–1362Loskutova E, Nolan J, Howard A, Beatty S. Macular pigment and its contribution to vision. Nutrients. 2013;39(5):1962-1969.Roark MW, Stringham JM. Visual performance in the ‘real world’: contrast sensitivity, visual acuity, and effects of macular carotenoids. Molecular Nutrition & Food Research. 2019;63(15):1801053Leat SJ, Legge GE, Bullimore MA. What is low vision? A reevaluation of definitions. Optom Vis Sci. 1999;76:198–211Akuffo KO, Beatty S, Peto T, et al. The impact of supplemental antioxidants on visual function in nonadvanced age-related macular degeneration: a head-to-head randomized clinical trial. Investigative Opthalmology & Visual Science. 2017;58(12):5347. doi:10.1167/iovs.16-21192.
Dr. Roark is the president of Allisonville Eye Care Center in Fishers, IN. He is a member of the American Optometric Association, the Indiana Optometric Association, and a Fellow of the American Academy of Optometry. Dr. Roark speaks frequently on the topics of contrast sensitivity and ocular nutrition. You may contact him at email@example.com.