It is still the symptoms: Patients care about how they see and feel
A study shows that blurred vision, especially while reading, is a symptom of dry eye disease.
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When I am on the road lecturing, either from the podium or in front of a small group of colleagues at a sponsored dinner, the same figures come up on somebody’s slide: 30 million Americans have dry eye disease symptoms, approximately 6.8 million are diagnosed, and at any one time only 1.2 million are receiving prescription treatment. After this slide goes up, the next thing I point out is that the number of symptomatic patients is determined by what we would consider traditional DED symptoms such as dryness, tearing, burning and the like. My take is, and always has been, that DED is the second greatest cause of blurred vision and other visual symptoms behind only “I forgot to put my glasses on.” If you add in vision problems, the number of people who suffer from DED is at least 60 million.
Not sure you believe the part about DED causing vision problems? Well Doubting Thomas/Thomasina, I have news for you. No less than Esen Akpek from Wilmer Eye Institute just published a paper in American Journal of Ophthalmology that proves it, at least with reading. That is not a typo; Dr. Akpek, who brought you the Sjö test (Bausch + Lomb) and who has been doing work on crazy hard stuff such as limbal stem cell deficiency and other DED mimics, wrote an article on DED and reading titled “Sustained gazing causes measurable decline in visual function of patients with dry eye.”
Akpek. Wilmer. Reading. Ha! Take that, you cynics.
Here is the skinny on DED and reading. Whenever you look at anything up close, no matter what it is, you blink much less frequently. Like, maybe as little as 50% as often as normal. As we get older, we also blink less frequently in general, and of course diseases of the elderly such as Parkinson’s cause a further decrease in blinking rates. When you are reading from a screen of any type — desktop, laptop, tablet, smartphone — we also know from LipiView (Johnson & Johnson Vision) data that whatever blinking we do is often comprised of incomplete blinks. It is amazing to watch the videos and see the pictures of patients who have dry eye and never seem to complete a single blink when tested. Couple this with the rapid tear breakup times we see with even mild degrees of meibomian gland dysfunction, and the mechanism of action causing blurred vision from DED is pretty clear.
It turns out that there is a validated test of out-loud reading, the International Reading Speed Texts (IReSt), which reports as words per minute (wpm). Study subjects with DED were compared with a control group without DED that was otherwise identical in all respects. There was no difference between the groups in either reading speed or the time it took them to read the test excerpt before the dryness challenge. After 30 minutes of silent reading, the DED group had both decreased reading speed and an increase in the length of time it took to read the test passage. The control group did not show any differences in either measurement. There were statistically significant differences between the two groups in both parameters after prolonged gazing (silent reading). In addition, each 1-point increase in baseline corneal staining led to a 5-wpm reduction in reading speed.
Intuitively, we all understand that a stable tear film and a smooth corneal surface are necessary to produce an optically “pure” presenting ocular surface. Not only has Dr. Akpek and her co-authors shown that DED affects reading vision, they have also coupled one of our key signs (corneal staining) with a proxy measurement for blurred vision. Patients who complain of blurred vision, especially those who have symptoms that are related to any near tasks, should be evaluated for the presence of any signs of DED (staining, tear breakup time, elevated or asymmetric tear osmolarity, etc).
This gives me the perfect opportunity to tell you all once again that the most important metric when treating DED is patient symptoms. It is vitally important to listen carefully to what they are experiencing and to accurately record how they are feeling. We should also try to measure their symptoms. Pick a symptom survey. Any validated survey. OSDI, SPEED, SANDE, it likely does not matter which one you choose as long as you use it. When patients are seen in follow-up, it is incredibly helpful to compare not only the “objective” survey score, but also to review and compare their symptom narratives. Your patient is not really interested in corneal clearance or the slope of tear osmolarity decline. All they know is how they feel and how well they see.
“You didn’t mention burning today, Mrs. Pistolaclioni” or “I’m so happy to hear that you are reading better” is more meaningful to your patient than their osmolarity trend.
So, a tip of the cap to Dr. Akpek and her team for giving us hard science to prove that blurred vision, especially while reading, is a DED symptom. I am not going to lie: It feels like validation to have a Wilmer professor publish a study that supports the position I have taken all of these years. DED is a real entity that has a significant impact on our patients’ lives. If you include those who have visual symptoms, there may be as many as twice the consensus number of active, symptomatic patients in the U.S. Symptoms drive the workup. Symptoms direct treatment. Ultimately symptoms determine the success of our interventions.
Symptoms matter.
- Reference:
- Akpek EK, et al. Am J Ophthalmol. 2020;doi:10.1016/j.ajo.2019.10.009.
- For more information:
- Darrell E. White, MD, can be reached at SkyVision Centers, 2237 Crocker Road, Suite 100, Westlake, OH 44145; email: dwhite@healio.com.
Disclosure: White reports he is a consultant to Allergan, Shire, Sun, Kala, Ocular Science, Rendia, TearLab, Eyevance and Omeros; is a speaker for Shire, Allergan, Omeros and Sun; and has an ownership interest in Ocular Science and Eyevance.
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