Handheld device use poses more stress on eyes, body than reading printed copy

Through live presentations, poster sessions and press conferences here at Academy 2008, the American Academy of Optometry’s annual meeting, researchers from around the world showcased their work in a range of areas, including the effect on the eyes and body of the use of popular handheld devices.

Significant differences were seen in viewing distance, blink frequency and subjective discomfort when using handheld computer devices compared to reading printed text, according to researchers at Pacific University College of Optometry’s Vision Performance Institute.

Yu-Chi Tai, PhD, reported at an academy-sponsored press conference that people who use handheld devices are encouraged to take frequent breaks and engage in more outdoor activities with distant viewing.

The purpose of this study was to examine the viewing distance and sensation of visual discomfort while performing handheld tasks compared to reading printed text at various font sizes, according to the study abstract. Thirty-four adults were tested under five situations: watching movies on an iPod, playing on a game station, thumb-keying text messages, searching a database with a stylus and reading text on a smart phone.

Yu-Chi Tai

“When reading hard copy, viewing distance is primarily determined by text size,” Dr. Tai reported. “When using handhelds, viewing distance is closer than when reading hard copies and is affected by task nature.”

The researchers hypothesized in the abstract that this was a result of text resolution and accommodative stress, “which eventually posed a limit to the visual angle.” Blink rate was also found to be much lower for handheld use than hard copy reading. In addition, subjects reported neck pain and eye strain, especially when playing games and searching a database.

“We found that after only 10 minutes of use, subjects experienced visual and body stress,” Dr. Tai reported.

“What you’re holding in your hand is more demanding on your focusing system and could affect your eye health if the distance is not appropriate,” she concluded

This research was sponsored by the Microsoft Advanced Reading Group to Pacific University Vision Ergonomics Laboratory.

Correlation found between lipid layer, tear film

Researchers from Ohio State University in Columbus reported that thicker lipid layers were found to be associated with reduced rates of pre-lens tear film thinning in contact lens wearers. Co-author Kelly K. Nichols, OD, MPH, PhD, FAAO (D), spoke during an academy-sponsored press conference on behalf on principal author Jason J. Nichols, OD, MPH, PhD, FAAO.

Kelly K. Nichols

“It’s been a challenge to determine what drives comfort in a patient who wears contacts,” Dr. Nichols said at the press conference. “The purpose of this study was to examine the simultaneous role of the tear film lipid layer as a barrier to tear film thinning in contact lens wearers.”

The 30 study subjects were current wearers of O2 Optix (lotrafilcon B, CIBA Vision) lenses and used Opti-Free RepleniSH (Alcon) solution. They were fitted in new lenses of the same type and provided with the same solution. According to the study abstract, “After 15 minutes of wear, interferometric measures … were used to derive pre-lens tear film thinning and lipid layer thickness.”

When they returned for 2-week follow-up, the lenses were stored for biochemical lipid analysis, Dr. Nichols said.

The study abstract notes “a strong correlation between lipid layer thickness and pre-lens tear film thinning … likewise, for the 2-week outcome visit there was also a strong correlation.”

Dr. Nichols reported: “There were no significant differences in lipid taken off lenses between the 15-minute period and the 2-week period.”

According to the abstract conclusion, “The use of this contact lens material and care solution combination was associated with sustained pre-lens tear film distribution characteristics.”

“Tear film thinning is associated with symptoms and due to evaporation – as indicated in previous findings,” Dr. Nichols said. “You can hypothesize that the lipid layer is important in maintaining the tear film layer on the lens and on the ocular surface. We can show the lens is just as it was 2 weeks earlier.

“Further studies could examine differences in patients who don’t have comfort over a 2-week interval or with other materials and care solutions,” she continued. “It could be that the phospholipids help maintain the surface wettability.”

Additional benefits of contacts for kids

Compared to glasses, contact lens wear offers improved vision-related quality-of-life benefits for children and teenagers. According to study findings presented at the American Academy of Optometry meeting, it is suggested that children who require vision correction should be given the option of being fitted with contact lenses.

The ACHIEVE (Adolescent and Child Health Initiative to Encourage Vision Empowerment) Study randomized 484 children ages 8 to 11 years with myopia of 1 D to 6 D to wear either spectacles or soft contact lenses. Using the Pediatric Refractive Error Profile (PREP), an instrument used to compare the vision-specific quality of life between children affected only with refractive error, researchers compared the two groups for 3 years.

According to a press release by Vistakon, which supported the study, children who wore contacts saw greater improvement in satisfaction with their choice of vision correction, appearance and participation in activities, with differences detected as early as 1 month.

Lead author Marjorie Rah, OD, PhD, FAAO, of New England College of Optometry, said in the press release, “Studies have shown glasses to be associated with negative attributes in areas of self-perception and attractiveness, so it’s not surprising that children experience quality-of-life benefits beyond vision correction from contact lens wear.”

Additional findings from the ACHIEVE study were released following Academy 2008. According to study authors, no clinically meaningful differences in axial length, corneal curvature or myopia were found between children wearing soft contact lenses and children wearing spectacles.

In another Vistakon press release, the study authors said that more significant differences found in earlier, shorter duration studies may have reflected transient changes, and that this long-term investigation with relatively infrequent visits did not show those fluctuations.

The data should reassure eye care practitioners concerned with the phenomenon of “myopic creep” associated with soft contact lens wear, the authors said.

For more information:

• Yu-Chi Tai, PhD, can be reached at Pacific University College of Optometry Vision Performance Institute, 2043 College Way, Forest Grove, OR 97116; (503) 352-2289; fax: (503) 352-2929; e-mail: ytai@pacificu.edu.
• Jason J. Nichols, OD, MPH, PhD, FAAO(D), is an assistant professor at Ohio State University College of Optometry. She can be reached at 320 West 10^th, Columbus OH, 43210; (614) 292-4979; fax: (614) 688-4474; e-mail: JNichols@optometry.osu.edu. Dr. Nichols has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Marjorie Rah, OD, PhD, FAAO, is an associate professor at the New England College of Optometry. She can be reached at e-mail: Marjorie_Rah@meei.harvard.edu. Dr. Rah is a paid consultant for Johnson & Johnson Vision Care.