Differences in Vision Between Clinic and Home

Original Investigation Research

Invited Commentary

How to Measure Vision in Glaucoma Jeffrey L. Goldberg, MD, PhD

How well do your patients with glaucoma see? In clinic with our patients, symptoms and signs of visual decline do not match. Some patients measure poorly on visual field testing but tell us they are doing just fine with their daily activiRelated article page 1554 ties. Others seem to do well on the eye chart and display only modest defects on perimetry but report significant visual limitations in their lives. How to explain these discrepancies? Are we not measuring actual vision? Certainly the visual needs of each patient strongly influence their symptoms, which lends a strongly subjective element to the reporting of visual quality of life. Patients with glaucoma who are still active and require fine acuity and highquality peripheral vision at work or at home might be more likely to notice and report small degradations in their visual experience. On the other hand, patients who are less visually active, have otherwise given up activities such as driving, or perhaps spend more time watching television than reading may be less likely to notice or report visual limitations, even if their measured defects appear severe. How to reconcile, then, measures of visual acuity and visual field in the clinic, and vision-related quality of life, generally assessed by patient report? Bhorade et al1 took an important step in addressing this question by examining differences in distance and near vision, as well as contrast sensitivity and glare testing, in patients with glaucoma and normal control participants, measured in the clinic and, using the same measures, in their homes. Patients with glaucoma, including open-angle and chronic-angle closure diagnoses, were defined by the presence of glaucomatous optic nerve cupping and reliable, reproducible visual field defects. The study excluded patients with other ocular diseases including nuclear sclerotic cataracts greater than grade 2, physical limitations, and impaired cognition. Patients with glaucoma were further subdivided into mild, moderate, and severe stages using the Glaucoma Staging System.2 A total of 175 patients with glaucoma and control participants were included in the final analysis. Looking at measures of vision, this study revealed that mean scores for distance and near visual acuity, and contrast sensitivity with and without glare, were all statistically significantly better in the clinic than at home.1 This difference was even greater for distance vision in the patients with severe glaucoma compared with control participants. How meaningful were these differences? More than half of all participants measured better distance vision in the clinic than at home, and about one-third of patients read 2 to 3 lines better in the clinic at distance. At near, about one-fifth read 2 to 3 lines better in the clinic compared with at home. Note that near vision at home was measured wherever the patient reported they did most of their close work, and distance vision at home was meajamaophthalmology.com

sured in the room patients used most. The large fraction of patients demonstrating such a meaningful difference in vision was striking. To some degree, this would seem to match the many other discrepancies we see—good intraocular pressures on clinic visits but progressive optic neuropathy that proves to be due to low compliance with ocular hypotensive therapy at home, or the mismatch between signs and symptoms discussed here. But Bhorade and colleagues1 expanded beyond the measured differences in visual acuity between the clinic and home and investigated for reasons why. Among the many factors they tested, including demographics and education, they found that home lighting was the factor with the strongest association with clinic-to-home differences in vision scores, whether for patients with glaucoma or control participants. Other variables, including age, sex, race/ethnicity, occupation, and the Geriatric Depression Scale score trended toward significance as well, but lighting remained the strongest in significance even in multivariate analyses. How different were lighting levels in homes with patients performing worse on vision scores? For patients demonstrating differences, clinic lighting was 4.3 times higher in the clinic than at home for distance vision and 2.8 times higher in the clinic than at home for near vision. At the measured lighting levels, 85% to 90% of patients had home lighting below levels recommended in at least 1 reference.3 At near, the use of direct task lighting at home, but rarely in the clinic, may also influence acuity and visual function for activities such as reading. In part, these data are not specific to patients with glaucoma—the same trends were found in the normal control participants, although findings were in some measures exacerbated in patients with glaucoma. Interestingly, there was no difference in home lighting according to glaucoma severity. This might suggest that as glaucomatous damage worsens, patients are not scaling up compensation by increasing home lighting. In what other ways are we underestimating the visual dysfunction or decline of our patients? Another recent study points out that our estimation of patient experience of their glaucomatous scotomas may not be on target. Rather than finding patients with glaucoma reporting tunneling of their vision, most patients viewing example pictures described either blurring or missing parts in their peripheral fields.4 Thus, the current article from Bhorade and colleagues reflects the best of research into vision loss: identifying where vision deficiencies are occurring, pursuing a hypothesis for an underlying cause, and proposing a solution that addresses the underlying deficiency. Of course, work remains: can we systematically improve patients’ visual activities by simply improving home lighting? It would be attractive to think that such a relatively simple intervention might greatly improve patient experience. JAMA Ophthalmology December 2013 Volume 131, Number 12

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Research Original Investigation

Differences in Vision Between Clinic and Home

As importantly, we need to pour more effort into measuring vision with relevant functional measures. Patient report of symptoms and function using quality-of-life measures, such as the Visual Functioning Questionnaire–25, are often included in larger studies and reported as outcomes. Moving from patient report to quantitative functional measures and studying not just a snapshot cohort but a longitudinal measure of function should be priorities. We should make an effort to look at functions in activities of daily living, such as reading speed and comprehension5 or driving ability, using laboratorybased simulators.6,7 Expanding visual field testing to measure real-world function with binocular useful field of view or integrated visual field might be another approach.8-10 ARTICLE INFORMATION Author Affiliation: Shiley Eye Center, University of California–San Diego, La Jolla, California. Corresponding Author: Jeffrey L. Goldberg, MD, PhD, Shiley Eye Center, University of California–San Diego, 9415 Campus Point Dr, 0946, La Jolla, CA 92093 ([email protected]). Published Online: November 21, 2013. doi:10.1001/jamaophthalmol.2013.5747. Conflict of Interest Disclosures: None reported. Funding/Support: The National Eye Institute (grant P30-EY022589) and Research to Prevent Blindness Inc are gratefully acknowledged for their support. Role of the Sponsor: The National Eye Institute and Research to Prevent Blindness Inc had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. REFERENCES 1. Bhorade AM, Perlmutter MS, Wilson B, et al. Differences in vision between clinic and home and the effect of lighting in older adults with and

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Finally, beyond our ability to measure and advise patients on their visual function, this study will be important to develop functional visual end points for future glaucoma studies. The motivation to identify intraocular-independent treatments for glaucoma, whether neuroprotective or regenerative or both, is high, and a number of such treatments have entered clinical trials.11 Developing Food and Drug Administration–approved end points for such glaucoma trials remains a major focus of research, and Food and Drug Administration representatives have in recent years maintained that such end points need to be rooted in measures that relate to or correlate with visual function.12 Thus, research in such measures, or closely related biomarkers, remains a major goal in glaucoma research.

without glaucoma [published online November 21, 2013]. JAMA Ophthalmol. doi:10.1001 /jamaophthalmol.2013.4995. 2. Brusini P. Categorizing the stage of glaucoma from prediagnosis to end-stage disease. Am J Ophthalmol. 2006;141(6):1169-1170.

8. Bentley SA, LeBlanc RP, Nicolela MT, Chauhan BC. Validity, reliability, and repeatability of the useful field of view test in persons with normal vision and patients with glaucoma. Invest Ophthalmol Vis Sci. 2012;53(11):6763-6769.

3. Rea M. IESNA Lighting Handbook. 8th ed. New York, NY: Illuminating Engineering Society of North America; 1993.

9. Chisholm CM, Rauscher FG, Crabb DC, et al. Assessing visual fields for driving in patients with paracentral scotomata. Br J Ophthalmol. 2008;92(2):225-230.

4. Crabb DP, Smith ND, Glen FC, Burton R, Garway-Heath DF. How does glaucoma look? patient perception of visual field loss. Ophthalmology. 2013;120(6):1120-1126.

10. Crabb DP, Fitzke FW, Hitchings RA, Viswanathan AC. A practical approach to measuring the visual field component of fitness to drive. Br J Ophthalmol. 2004;88(9):1191-1196.

5. Burton R, Crabb DP, Smith ND, Glen FC, Garway-Heath DF. Glaucoma and reading: exploring the effects of contrast lowering of text. Optom Vis Sci. 2012;89(9):1282-1287.

11. Chang EE, Goldberg JL. Glaucoma 2.0: neuroprotection, neuroregeneration, neuroenhancement. Ophthalmology. 2012;119(5):979-986.

6. Medeiros FA, Weinreb RN, R Boer E, Rosen PN. Driving simulation as a performance-based test of visual impairment in glaucoma. J Glaucoma. 2012;21(4):221-227.

12. Weinreb RN, Kaufman PL. Glaucoma research community and FDA look to the future, II: NEI/FDA Glaucoma Clinical Trial Design and Endpoints Symposium: measures of structural change and visual function. Invest Ophthalmol Vis Sci. 2011;52(11):7842-7851.

7. Szlyk JP, Mahler CL, Seiple W, Edward DP, Wilensky JT. Driving performance of glaucoma patients correlates with peripheral visual field loss. J Glaucoma. 2005;14(2):145-150.

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