Getting the Right Frame + Fit for Myopia Lenses

With Essilor Stellest lenses now available in the United States and more myopia-control spectacle lens options on the horizon, opticians are increasingly being tasked with fitting these specialized lenses. However, unlike conventional spectacle lenses, myopia-control lenses require additional attention to help ensure treatment effectiveness.

One of the key factors on this front today is selecting the proper eyeglass frame size and shape. Ultimately, though, the child must personally like the frame selected because they’re the one who must commit to wearing their eyeglasses for 10 hours per day in order for the myopia-control lenses to be effective, says myopia expert Dwight Akerman, OD, MBA, FAAO, Dipl AAO.

“Children are far more likely to wear their glasses consistently when the frame actually feels like theirs—stylish, comfortable, and properly fitted to their face,” he says. “This matters even more with myopia-control lenses, since the optical zone must remain precisely centered over the pupil. A poorly fitted frame undermines centration and can significantly reduce treatment efficacy.”

Other crucial myopia lens success factors include proper lens centration, on-target measurements, extras like straps and nosepads to aid with centration, and patient compliance with frame choice. Here, we cover the key areas to ensure long-term frame-and-lens success for myopia management patients.

Frame Size and Shape Matter

Different Rx ranges have different lens blank sizes, which can dictate the parameters of the frame. Registered optician Cailin Harrop, who has had access to myopia-control eyeglass lenses in Canada for about four years, suggests calculating minimum blank size both horizontally and vertically before the patient leaves and comparing that with the available blank size in their Rx range.

Generally, the higher the prescription, the smaller the available blank size, “which means for a -12, we can’t choose a really large rectangular frame that requires a lot of decentration, because the lens is so small it won’t cut out,” says Harrop, who is the department head of the optical services department in the Waterloo Eye Institute.

Based on her years of experience fitting myopia-control eyeglass lenses, including second-generation peripheral defocus lens technology available in Canada, Harrop has determined that rectangular frames are better with larger lens blanks, while smaller blanks can work in rounder frame shapes. “With rectangular frames, you need a larger lens blank, otherwise you’ll end up with a corner that doesn’t cut out. A softer or rounder shape frame is more conducive to smaller lens blanks. Rounder frames are less likely to result in cut out issues compared to rectangular frames.”

Again, she warns that centration is of utmost importance when choosing a frame and fitting the lenses. “There’s no way to know if there will be a cutout issue until you actually have the centration measurement,” Harrop says. “Once you know where the optical center will be within the frame, then you can do a quick calculation to determine if that frame is an appropriate choice. Use the centration chart with the frame to confirm if the lenses will cut out based on the location of the patient’s optical center. Avoid frames that are too deep or too wide. The more centered their pupils are (vertically and horizontally), the better.”

Harrop also recommends not using a high-base-curve frame. “Find a frame that has as little wrap as possible, because more wrap means we are creating more distortion, and we want to avoid distortion as much as possible,” she says. “If it curves beyond where the lens ends, that’s okay. But you want to avoid having a high base curve requirement for the lens itself, where the part of the frame that’s holding the lens is as flat as possible.”

The Importance of Centration

The most important measurement when fitting a young myope with myopia-control spectacle lenses? According to Harrop, it is monocular pupillary distance (PD). Measuring PD monocularly helps ensure optimal centration, she says, which is essential when aligning myopia-control lenses properly within a frame.

“The most important factors for centration would be monocular PDs,” says Harrop. “That way, if there’s a few millimeters difference, we’re taking that into account when we’re actually putting the optical center inside the frame for that patient’s measurements.”

Myopia-control spectacle lenses are most effective when centration is as near to perfect as possible. When compared with fitting regular spectacle lenses, “making sure the pupil is centered is that much more important,” with myopia-control lenses says Harrop. “It’s important they’re looking through the small correction zone and not constantly looking through the treatment zone. The treatment zone should surround the eyes on all sides. If they’re wearing a myopia-control lens and they’re not looking through the correct part of the lens, the therapy will be less effective.”

Therefore, she recommends choosing a frame that requires minimal decentration and says the geometric center distance (frame PD) should ideally be similar to the patient’s pupillary distance.

Take All Position-of-Wear Measurements

In addition to taking the PD monocularly, ideally with a pupilometer, other position-of-wear measurements are important when fitting a young myope with myopia-control eyeglass lenses. These include pantoscopic tilt, the vertical angle of the lens as it sits on the face, and vertex distance, the distance between the cornea and back of the lens.

“To maximize the efficacy of the spectacle therapy, the optical zones in the lens must align with the visual axis of the eye,” Harrop says.“Measuring wrap, vertex distance, and pantoscopic tilt mitigate the chance of misalignment and ensure the lenses are having the desired effect.”

In most cases, the lens supplier offers the software and devices for taking these position-of-wear measurements. However, Harrop suggests manually confirming these automated measurements. “Opticians prefer to double check those manually just to make sure that the digital measuring device is capturing them to the degree that we’re measuring manually.” Also, check the child’s posture when measuring the pantoscopic angle to make sure they are not tilting their head.

Straps and Nose Pads Aid with Centration

After the child’s position-of-wear measurements have enabled precise positioning of the lenses, keeping them there is the next challenge. Accessories such as straps and nose pads can “contribute to an appropriate and secure fit,” says Harrop, particularly in very young children.

“When the child is wearing the glasses with a head strap, pantoscopic tilt is especially important to consider,” she notes. “Pulling the strap tight tends to decrease panto, rotating the top of the frame in toward the face and the bottom of the frame away from the face. Educating parents on proper strap tension is important at the time of dispensing.”

Nose pads help stabilize the frame to ensure centration in at least two ways. Because children tend to be more active, frames without nose pads can easily slide down the face. Nose pads will keep the frame in place even on active children.

“The active child tends to be up and down on their hands and knees crawling and running around, which doesn’t always lend itself to keeping regular glasses in place,” says Harrop. When wearing frames with nose pads, young myopes “don’t have to be limited in their play, but they’re still getting the benefit of the lenses,” she says.

Nose pads also help maintain a frame’s position on younger children who do not have fully developed nose bridges. “If you put a plastic frame that doesn’t have nose pads on a flat bridge, it’s a little bit more likely to sit low or to slip down,” warns Harrop. “Because you want to prevent those glasses from slipping down, we’ll often use nose pads with anti-slip materials like a silicone type material that can be replaced and exchanged as needed if it starts to wear and lose some of that grippiness. A stable, non-slipping frame is crucial to maximize the therapeutic benefits of myopia-control lenses.”

Follow-Up Adjustments

Finally, once the frame is selected and fitted with a lens and the eyeglasses are dispensed, “we counsel the parents and children that the fit of the frame is extremely important and adjustments are needed regularly,” says Harrop. “Anything is fixed with a complimentary adjustment that’s all part of the myopia treatment process.”

Harrop sums up the features she looks for in a frame for myopia-control lenses: “Flexible, indestructible, optional straps and built-in nose pads—those are all features of frame brands that we favor when we’re fitting a child with myopia-control lenses.”