Multifocal Contact Lens Use Subjectively Relieves Muscle Strain in Computer Workers

Wearing multifocal contact lenses (MFCLs) appears to subjectively enhance comfort while performing computer work compared with general purpose-progressive addition lenses (GP-PALs), according to a study published in Optometry and Vision Science.

Researchers conducted a randomized crossover study including 11 right-handed presbyopic workers (mean age 55±4 years, 6 men) who had normal vision. All participants worked for at least 4 hours per day, 4 days per week with a regular visual display unit. The primary objective was to assess the amplitude distribution function, number of gaps (interruptions in muscle activity), and sustained low-level muscle activity period for patients wearing GP-PALs or MFCLs during computer work. 

Investigators randomly assigned participants to either MFCLS or GP-PALs based on a nonindividual, fixed design. They performed surface electromyography on the sternocleidomastoid muscle, the upper trapezius, and the semispinalis during 30 minutes of continuous computer work on an optimally adjusted visual display unit. They also performed subjective refraction, biomicroscopic evaluation, and obtained demographics. Participants reported workload, psychological stress, and test item satisfaction along with symptoms of dry eye disease through the Ocular Surface Disease Index (OSDI). Overall, the team conducted a total of 5 visits. 

Although the researchers did not observe any significant muscle load differences between patients with MFCLs and GP-PALs, they noted that participants who wore MFCLs reported being more comfortable while performing computer tasks (P =.003).

OSDI scores increased for both MFCLs and GP-PALs, but the increase only reached statistical significance in the MFCL participants (P =.01).

Investigators also noted that participants wearing GP-PALs tended to have 5±3.3° greater head inclination compared with MFCLs (P =.003), and patients in the MFCL group experienced more gaps compared with GP-PAL wearers (44 vs 15).

The researchers attribute the lack of statistically significant reduced muscle activity with MFCLs compared with GP-PALs to small sample size and high data variability.

“It seems that there is no ‘one size fits all’ solution for an optimal correction at the visual display unit,” according to the investigators. “It is a challenge for optometrists to find an appropriate solution for the correction of presbyopia regarding specific workplace design requirements.” 

However, they acknowledge that “use of the lenses increased subjective perception of comfort with equivalent visual quality and comparable tolerance, and thus, modern MFCLs may be an alternative for computer workers.”

Study limitations include a small sample size.

Reference

Kolbe O, Bitterlich K, Lahne J, Degle S, Anders C. Surface electromyography of the trapezius and sternocleidomastoid during computer work with presbyopic corrections. Optom Vis Sci. 2022;99(6):496-504. doi:10.1097/OPX.0000000000001899