Introduction: Spectacles is the main option in treating myopia (shortsightedness) and improve vision. Apart from treating myopia, spectacles can also be used to control further progression of myopia. Spectacles are among the most favored approaches as it can be easily fitted even in younger children. Additionally, the spectacles have little or no side-effects compared to other optical treatments.
These are the standard type of spectacle lenses typically prescribed for vision problems in children and adults. These spectacles only have one focusing distance (far or close). Single vision spectacles are used only for vision improvement in children with myopia. But in children who shows significant worsening of myopia, these spectacles do not have the advantage of slowing down the progression of myopia.
Bifocal spectacle lenses are like two lenses stuck together – the top half corrects for long distance vision and the bottom half corrects for reading and up-close vision. Bifocals are frequently prescribed to children having problems with near focusing and eye coordination problems. Bifocal spectacle lenses have also been shown to slow down myopia progression in children compared to single-vision spectacles. The main drawback of bifocal spectacles is the appearance of the line in the middle of the lens.
Progressive addition (PAL) lenses, also known as multifocal spectacle lenses, have a graded power from the long distance correction at the top to the full reading power at the bottom of the lens. They can be thought of like a bifocal but without the visible line in the middle.
PALs prescribed to any myopic child show very minimal effects for myopia control, however for children with having problems with the near focusing and coordination problems, they have been shown to slow myopia progression.
The strategies of controlling the myopia progression were based on inducing relative myopic defocus. When the peripheral retina receives myopic defocus, it will slow-down the eye from growing longer as shown in animal models. On the basis of these theories, various myopia control-specific spectacle lenses have been developed and researched.
These include the peripheral plus design. These lenses have distance correction at the center for clear central vision with asymmetric design at the periphery incorporating continuous plus power for altering peripheral optics.
ii. The Defocus Incorporated Multisegment Spectacle (DIMS) lens.
This is known as Defocus Incorporated Multisegment Spectacle (DIMS) lenses. The D.I.M.S. spectacle lenses has around 400 multiple segments of plus powered lenslets in the mid-peripheral portion of the spectacle lens surrounding a clear central zone for distance refractive correction. Each segment is approximately 1mm in diameter. The multiple segments induce myopic defocus at the retina periphery while simultaneously providing clear central vision.
Age: Younger ages are associated with greater annual myopic progression, and thus early-onset myopia is likely to result in higher levels of final net myopia. Thus, spectacles for myopia control can be prescribed at younger ages.
Wearing time: No correlation was observed for myopia control treatment effect and spectacle wear time. Nevertheless, myopia control spectacle wear during all waking hours is recommended for better myopia control treatment effect.
Eye examinations: It is evidenced that younger age groups benefit highly from myopia control treatments. With younger age groups associated with greater annual progression, it is recommended to conduct half-yearly or yearly eye examinations while using myopia control treatments.
Fitting requirements: Most of these myopia control spectacles have a clear central portion for distance vision and mid-peripheral or peripheral portion having multiple plus powered lenslets or contrast reduction dots. It is essential to follow the appropriate fitting guide.
Your eye care practitioner will be the best guide of which option is most suitable for your child, as it can depend on their level of myopia, eye muscle coordination, age and more. It’s important for you to also understand the influence of your child’s visual environment – outdoor time and screen time – on successfully managing their myopia.