Prolonged silent reading a feasible tool to quantify dry eye
Silent reading for as little as 30 minutes may induce measurable changes on the tear film and ocular surface in individuals at least 50 years of age, especially in those with dry eye, a study has found.
“Evaluating tear film and ocular surface parameters at rest may miss clinical findings brought about by common everyday tasks such as reading, leading to discordance between patient-reported symptoms and clinician-observed signs,” researchers said.
“Quantifying dry eye after visually straining activities such as prolonged silent reading may help better understand patient symptomatology,” they added.
In the study, researchers asked 177 patients with dry eye (mean age 63.2 years) and 34 normal controls (mean age 60.4 years) who completed the Ocular Surface Disease Index (OSDI) questionnaire to read a 30-minute validated passage silently. All participants underwent the following tests before and after the reading task: automated noninvasive tear break-up time (TBUT), surface asymmetry and regularity indices, Schirmer’s testing, and corneal and conjunctival staining.
After the reading task, all parameters, except the surface asymmetry index, worsened in both the dry eye and control groups. The worsening was notable for corneal and conjunctival staining in the dry eye group (p<0.001) and for corneal staining in the control group (p<0.01). [Ophthalmology 2018;doi:10.1016/j.ophtha.2018.03.039]
Baseline OSDI scores correlated with prereading corneal and conjunctival staining scores (p=0.006 and p<0.001, respectively), as well as with postreading TBUT (p=0.03) and corneal and conjunctival staining scores (p<0.001 and p=0.001, respectively).
Changes in TBUT and Schirmer’s test scores correlated significantly with their respective baseline values (p<0.001 and p<0.001). “[This] indicates that the more unstable the tear film and the lower the aqueous tear secretion, the worse they became after the prolonged reading task,” researchers explained.
Finally, worsening in corneal staining was directly correlated with the baseline conjunctival staining score (p=0.02) and surface regularity index (p=0.01).
“Our findings indicate that prolonged reading represents an inexpensive tool that simulates a real-life desiccating stress with quantifiable changes on the ocular surface correlating well with subjective patient symptoms measured at baseline,” researchers said.
In comparison, a controlled chamber that simulates factors such as temperature, humidity changes and airflow/wind—which are known to exacerbate clinical signs and symptoms in patients with dry eye—to quantify the effects of adverse environmental conditions on the ocular surface is expensive to build and provides exaggerated environmental conditions rather than mimicking a real-life situation.
“Indeed, a previous study hypothesized that a reading challenge can function similarly to an environmental challenge and increase the magnitude of dry eye parameters to observable clinical findings,” researchers noted. [Cornea 2015;34:917-921]
The study might be limited by the inclusion of only older individuals, performance of tests in a nonmasked fashion, and lack of data on the blink rate or pattern or measure of the tear film secretion rate or evaporation, thus preventing investigation into exactly how prolonged reading causes alterations in the tear film and ocular surface.