Effects of Gunnar Computer Glasses on Viewing Comfort and Performance

<Introduction>

When performing near work, one must focus at (accommodate) and point toward (converge) at a closer distance and constantly re-focus the eyes to see small text and images with clarity. Sustaining such efforts can lead to eye fatigue and eye strain, among a host of vision problems. Most visual tasks on a screen also demand heightened visual concentration, and this decreases blink rate. Working in a heated or air-conditioned office environment leads to over-evaporation of the tear film, and lipid deficiency, irritation, and dryness to the corneal surface are expected. Disruptive glare from excessive screen reflection and ambient lighting also deteriorates the image quality and heaps on viewing discomfort. Extensive screen viewing also exacerbates discomfort in people with existing vision problems like eye muscle imbalance, astigmatism, farsightedness, and presbyopia. Since technology is almost unavoidable to modern life, preventions should be taken to lessen the total toll on the eyes and visual system. Gunnar computer glasses address the above issues by providing mild yellow tint anti-reflection coating to shield the harmful blue light and lessen strong glare. The glasses also have a small amount of magnification (+0.5 D) to enhance acuity. The curved frame is designed to retain moisture and reduce dry eye symptoms. All these special characters are devised to enhance visual performance and minimize eye fatigue and visual discomfort in digital viewing. The current study aimed to validate the benefits mentioned above.

Gunnar over-the-counter (OTC) computer glasses adopt yellow lenses to cut off the active short wavelength and lessen the bright glare, which often induces the detrimental effect caused by excessive illumination or intense scattered reflection. While the benefit of glare reduction is well received, the benefit on visual performance has been inconclusive. Some studies reported a significant enhancement in contrast sensitivity, but some failed to see any improvement in visual acuity and contrast sensitivity, even with color distortion. Without argument, tinted lenses reduce the transmittance of the visible spectrum and change the visible color to a certain degree. However, there has been a report that reducing the retinal illumination level does not necessarily lead to reduced brightness; instead, the visual system automatically adjusts for the illumination discounting, possibly with the help of increased pupil size. In addition, with the decrement of blue lights arriving at the eyes, both scattered reflection and chromatic aberration are reduced. Together, it is reasonable to believe that the visual acuity, contrast sensitivity, and chromatic discrimination will not suffer and may, instead, benefit from the filter of yellow lenses. These basic visual functions may, in turn, lead to enhancement in general visual performance such as routine office work. These will be tested in the proposed study.

The current study tested if Gunnar's OTC computer glasses provide any advantages, in comparison to no glasses, on the following aspects in computer-related office work:

• Any enhancement on the visual performance of the basic visual function, including visual acuity, contrast sensitivity, color discrimination, etc.
• Any enhancement on the visual performance of typical office work, including reading, word-spelling check, number searching, or target identification.
• Any benefit in preventing dry eye by measuring the humidity outside and inside the frame (only in the visit with Gunnar glasses) and the tear film break-up time after viewing for a prolonged period.
• Any benefit in objective viewing comfort measured with viewing distance, blink frequency, post-viewing pupil size.
• Any benefit in subjective viewing comfort reflected on the questionnaire of viewing symptom survey.
• Any benefit in viewing comfort and visual performance with increased environmental ventilation.
• Any benefit in viewing comfort and visual performance with increased environment under the intense glare.
• Any benefit in life quality from daily wearing (e.g., viewing comfort, sleep quality, or quantity due to the amount of stimulation from blue light)?
• Their willingness to purchase (select) the tested Gunnar OTC glasses and the price willing to pay for.

<Study design>

Thirty-four subjects, age 18 to 42, were planned to be recruited. This sample size is based on a priori power analysis with 80% and a medium effect size at alpha equal to 0.05. Subjects will be stratified into four age groups. An about equal number (8±1) of subjects should have been recruited for each group:

• 18-23 yr old
• 24-29 yr old
• 30-35 yr old
• 36-42 yr old

Each subject was scheduled for three visits: Visit 1 for screening and consenting, visit 2 for lab test after treatment 1, and visit 3 for lab test after treatment 2. Between visits was an adaptation period for the assigned treatment.

Visit 1: A screening visit

• Day 1, when a subject first joins the study
• Obtain informed consent and screening measurements (VA, contrast sensitivity, tear film break-up time as dry eye measurement, Dry eye questionnaire (OSDI), viewing symptom survey (VSS), history of dry eye, and computer work behavior).
• At the end of the visit, half of the subjects were given a pair of Gunnar OTC glasses for adaptation for 3 - 7 days; the other half were given no treatment. All subjects were told to work in front of a computer for at least 4 hours a day, with the assigned glasses if given.

Adaptation 1:

• Starting on Day 1, for 3 to 7 days, the subject was asked to work in front of computers for at least 4 hours each day with assigned treatment 1.

Visit 2: Lab test for treatment 1

• On a day between day four and day 8 convenient to the subject, the subject came to the lab with the assigned glasses condition.
• Baseline measurements will be taken, followed by a few visual tasks under three viewing conditions. The subject was asked to fill out the VSS, given a break, before being tested on another round of tasks under a different viewing condition.
• The total testing time is about 70 minutes for each condition and about 4 hours to complete the visit.
• The lab testing procedure is described below.
• At the end of visit 2, treatment was alternated for another 3-7 days of adaptation.

Adaptation 2 with treatment 2:

• Starting on the day of Visit 2 after the test, the subject adapts to the second treatment (with Gunnar glasses or without any glasses) for another 3 to 7 days.

Visit 3: Lab test for treatment 2

• The same procedure of Visit 2 was repeated.
• Subject was asked to rate their preference of wearing the Gunnar Glasses over no-glasses when performing computer tasks.
• After this visit, the study was completed for the subject.

Details of lab testing procedures:

• The study adopted a crossover design. Each subject went through three viewing conditions (control, bright light, strong ventilating) based on a Latin Square order.

1. In the control condition, the subject will perform all tasks under regular office lighting (500 lux) and the default lab ventilation condition.
2. In the bright light condition, the ambient light will be increased to 1500 lux.
3. In the strong ventilation condition, a ceiling fan will be positioned on top of the subject at the ceiling light location to increase the airflow. Visual performance tasks:

• Baseline measurements (10 min): Upon arrival, the subject was asked to fill out VSS and OSDI. Measurements of dry eye condition, pupil size, accommodation status, and blink rate were taken as the baseline for a visit.
• Under viewing condition 1:

1. Visual tasks (60 minutes): Visual acuity, contrast sensitivity, color perception, visual search of numbers among a number matrix, low-contrast target search, text reading, and spelling check were performed by a fixed order.
2. Post-task measurements of dry eye measure (Tear break uptime), pupil size, accommodation, and blink rate, as well as VSS were taken.

• Break time of 5-10 minutes.
• Repeat the above procedures for the other two viewing conditions.
• Total time for one lab visit was about 4 hours.