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Younger adults’ eyes are now confronted by the perfect storm of longer periods spent in front of streaming content on laptops to smaller text read on mobile devices held even closer to the face. Further, asthenopia can be brought on by an irritated ocular surface, as well as by heterophoria or accommodative lag in myopia.
Previous studies have explored current antifatigue eyeglasses with a modest plus boost placed lower on the lens. Investigators of a new, double-blind study have analyzed effects of low- and high-add multifocal soft contact lenses on visual fatigue experienced by individuals 18 to 35 years of age, as reported in Contact Lens & Anterior Eye. Results are pertinent for clinicians considering add lenses for pre-presbyopes, and comparing multifocal contacts to antifatigue spectacles.
The investigation included 24 participants with manifest refractions ranging from spherical equivalent -1.00 D to -7.88 D, accommodative lag of >+0.75 D, and mean baseline scores in the Convergence Insufficiency Symptom Survey (CISS) of 25.04±4.58. CISS scores were reduced to 24.46±4.59 after wearing single vision (SV) contacts for 1 month. In month 2, patients were randomly assigned to low- or high-add contact lenses, and crossed over to the other multifocal in month 3. CISS results markedly decreased to 12.17±6.89 after using low-add contacts, and 13.71±7.23 following high-add lens wear (both P <.01).
Data showed no statistically significant difference in accommodative lag after use of SV or multifocal contact lenses compared with habitual eyeglass wear. However, smaller changes occurred, including a mean lag of 1.67±0.36 D after SV lenses compared with 1.63±0.50 D for low-add, or 1.43±0.61 D after high-add lenses. These values are similar to habitual spectacle mean lag of 1.52±0.48 D.
For distance heterophoria, post hoc data revealed no significant differences between low-add lens wear and spectacle use (P =.11), but with high-add contacts, change was greater (P =.02). In near heterophoria, no important differences were found for any lens condition (P =.06). Distance phoria directional shift when comparing eyeglass wear to any contact lens assignment was minor, and esophoric. In near phoria, greater exophoric shifts were detected for both low- and high-add contact lenses compared with spectacles.
Prior research has discovered links between accommodative lag and asthenopia in near work. The current study, though, showed sizable reductions from multifocals in CISS scores without comparable changes in accommodative lag. Lag was measured with monocular estimate method (MEM) retinoscopy, and right eye data was used. Although accommodation did not significantly change, heterophoric improvements may have eased fatigue.
Patients of a Singapore-based optometric clinic were enrolled for this analysis, and all had previous contact lens experience. This study was limited by a small, regional cohort. An advantage was the use of SV and multifocal lenses made of the same material and water content; Air Optix® Aqua and Air Optix Aqua Multifocal (Alcon Vision LLC).
“Low-add multifocal contact lens(es) provided the largest reduction in CISS score, so are therefore more clinically viable and appropriate to provide an optimal balance between efficacy and safety in these individuals,” investigators suggest.
Reference
Ong ACH, Cruickshank FE, Sheppard AL, Davies LN. The efficacy of multifocal soft contact lenses for the alleviation of asthenopic symptoms in myopes with accommodative lag. Cont Lens Ant Eye. Published online September 9, 2021, doi:10.1016/j.clae.2021.101514
