THERE ARE TREATMENT options for myopia that can limit its development in patients with the goal of preventing high myopia. In the soft contact lens realm, there are several commercially available designs, including an off-the-shelf, U.S. Food and Drug Administration (FDA)-approved design for myopia control. It’s also possible to design custom lenses. Following are some tips on evaluating soft contact lenses for myopia management (MM).
LOOK AT SAGITTAL DEPTH
Like GP lenses, soft lens designs may be evaluated with fluorescein patterns (using high molecular weight fluorescein). For example, if the lens has too much sagittal depth, the fluorescein pattern will glow brightly from the excessive post-lens tear layer. Excessive sagittal depth may cause the lens to decenter inferiorly and fluctuate vision.
In this case, decrease the sagittal depth by either flattening the base curve or decreasing the lens diameter. To aid design, many laboratories have online calculators that create custom MM soft lenses using corneal sagittal depth data.
PRESCRIBE APPROPRIATE ADD POWER
When fitting soft lenses for MM, prescribing an add power that will allow for enough defocus to offer effective treatment is imperative. The Bifocal Lenses In Nearsighted Kids (BLINK) study demonstrated that treatment with commercially available high-add-power (+2.50D) aspheric multifocal (MF) lenses reduced the rate of myopia progression more effectively compared to either the medium-add-power (+1.50D) MF or single-vision designs (Walline et al, 2020). Therefore, when prescribing soft MF lenses for MM, consider fitting children in higher add powers to best decrease myopia progression.
ASSESS QUALITY OF VISION
Contrast Sensitivity MF optics are associated with disturbance in visual quality, especially in low-light settings (Huang et al, 2020). These visual disturbances increase with increasing add power. Fortunately, most children easily adapt to MF optics and report good stereo acuity (García-Marqués et al, 2020). If patients are bothered visually, consider prescribing up to –0.50D more distance power.
Binocularity Both aspheric and concentric-ring-design center-distance MF lenses can be prescribed for MM. Aspheric MM designs consist of a central distance zone that gradually transitions into the full defocus add power at the end of the optic zone. In contrast, concentric ring designs have a central distance zone surrounded by alternating rings of near and distance power that extend throughout the remainder of the optic zone.
Switching from spectacles to contact lenses affects convergence and accommodative demands (Robertson et al, 1967). Interestingly, children wearing MM concentric-ring-design soft lenses showed no changes in binocular and accommodative function in over two years of follow-up (Ruiz-Pomeda et al, 2019).
Children wearing commercially available aspheric MM soft lenses exhibited reduced accommodative responses and more exophoria at increasingly higher accommodative demands compared with those wearing single-vision lenses (Gong et al, 2017). Thus, the type of MF design should be carefully considered in children who have atypical phoria measurements or symptomatic double vision at near.
Using contact lenses to limit the development of myopia is an evidence-based treatment that is effective when prescribed correctly. To be most effective, treatment begins as early as possible, and even young children are good candidates for lens wear. By following these guidelines, the chances of successfully limiting myopia in young patients are quite good. CLS
- Walline JJ, Walker MK, Mutti DO, et al. Effect of High Add Power, Medium Add Power, or Single-Vision Contact Lenses on Myopia Progression in Children: The BLINK Randomized Clinical Trial. JAMA. 2020 Aug 11;324:571-580.
- Huang X, Wang F, Lin Z, et al. Visual quality of juvenile myopes wearing multifocal soft contact lenses. Eye Vis (Lond). 2020 Jul 19;7:41.
- García-Marqués JV, Macedo-De-Araújo RJ, Cerviño A, García-Lázaro S, McAlinden C, González-Méijome JM. Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens. Ophthalmic Physiol Opt. 2020 Nov;40:718-727.
- Robertson DM, Ogle KN, Dyer JA. Influence of contact lenses on accommodation. Theoretic considerations and clinical study. Am J Ophthalmol. 1967 Nov;64:860-871.
- Ruiz-Pomeda A, Pérez-Sánchez B, Cañadas P , Prieto-Garrido FL, Gutiérrez-Ortega R, Villa-Collar C. Binocular and accommodative function in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS). Graefes Arch Clin Exp Ophthalmol. 2019 Jan;257:207-215.
- Gong CR, Troilo D, Richdale K. Accommodation and Phoria in Children Wearing Multifocal Contact Lenses. Optom Vis Sci. 2017 Mar;94:353-360.