Glasses for a Strong Prescription: Thinner Lenses and the Right Frames

The short answer: a strong prescription does not have to mean thick, heavy glasses. Three choices do most of the work: a thinner lens material (high-index), an aspheric lens design that flattens the curves, and a frame that is the right size and shape for your face and your prescription. Get those three right together and lenses can be a quarter to a third thinner than standard plastic, lighter on your nose and far less noticeable. At Reimbold Eye Group in Alpharetta, our doctors and opticians plan all three at the same visit.

Why strong prescriptions make thick lenses

A lens bends light by being thicker in some places than others. The stronger the prescription, the bigger that difference has to be.

• Nearsighted (minus) prescriptions are thinnest in the middle and thickest at the edges. The thickness shows at the sides of the frame, and the lenses make your eyes look a little smaller.
• Farsighted (plus) prescriptions are thickest in the middle. They can bulge forward, feel heavy and make your eyes look larger.
• Astigmatism adds power in one direction, so one part of the edge can be noticeably thicker than the rest. If astigmatism is part of your prescription, our post on correcting astigmatism without surgery explains how it is measured.

The size of the lens matters as much as the power. A minus lens gets thicker the farther its edge sits from the center, so a large frame turns a moderate prescription into a thick one.

Lens materials, from standard to thinnest

Every lens material has a refractive index, a number that describes how strongly it bends light. A higher index bends light more, so the lens can be made thinner for the same prescription.

• Standard plastic (1.50). Excellent optics and very little color distortion. A good choice for mild prescriptions.
• Trivex (1.53) and polycarbonate (1.59). Light and very impact-resistant, with built-in UV protection. These are our go-to materials for children, sports and drilled rimless frames. Polycarbonate is softer, so it always gets a scratch-resistant coating.
• Mid high-index (1.60). Thinner than standard plastic with clear optics. Often a sweet spot for prescriptions in the moderate range.
• High-index (1.67). A common choice once prescriptions pass about plus or minus 5 or 6, especially for nearsighted lenses with thick edges.
• Ultra high-index (1.74). The thinnest plastic lens in common use, meant for very strong prescriptions. It is best in full-rim or semi-rimless frames and is generally not drilled for rimless mounts.

Those ranges are guidelines, not rules. Frame size, lens shape and the distance between your pupils can move the decision one step up or down, which is why we choose the material after the frame, not before.

The trade-offs to know about

• Color fringing. Higher-index materials spread light into colors a bit more (they have a lower Abbe value). Most people never notice, but some see faint color edges when looking through the sides of a strong lens. Precise centering keeps this to a minimum.
• Reflections. High-index lenses reflect more light than standard plastic, so an anti-reflective coating is a must. It also lets people see your eyes instead of glare.
• Impact resistance. High-index plastics are not as tough as polycarbonate or Trivex. For kids, sports and safety glasses, toughness wins over thinness.

Aspheric and digital lens designs

A traditional lens uses one curve across its whole front surface. An aspheric lens gradually flattens toward the edge. That lets the whole lens sit flatter and thinner, reduces how much your eyes look magnified or shrunk, and gives clearer vision when you look off to the side. Digitally surfaced lenses take this further by shaping the lens to your exact prescription and how the frame sits on your face. Our article on why a luxury frame deserves a luxury lens and our custom luxury lenses page explain the measurements behind these designs.

How to choose a frame for a strong prescription

1. Go smaller. A moderate lens width keeps the thickest part of a minus lens closer to the center. Oversized frames are the most common reason strong lenses end up thick.
2. Center your eyes. Look for a frame where your pupils sit near the middle of each lens opening. When the frame's width matches the distance between your eyes, the lens does not have to be cut off-center, and both edges stay thinner.
3. Favor rounder shapes. Round, oval and softened rectangle shapes have more even edges than wide, angular or deep cat-eye shapes, which push one corner far from the center. Our face shape glasses guide shows which of these flatter your features.
4. Let the rim do the hiding. A full-rim acetate frame with a slightly thicker front can tuck the edge of a minus lens almost out of sight. Thin metal and rimless frames show more of the edge, and semi-rimless frames show the bottom edge. Our frame materials guide compares acetate, titanium, horn and wood.
5. Sit close to the face. Adjustable nose pads or a well-fitted bridge keep the lenses close to your eyes, which reduces magnification and makes the lenses look and feel lighter.
6. Think about weight for plus lenses. Thick-centered plus lenses are heavier, so a smaller lens and a lightweight material such as titanium help them stay comfortable all day.

Our opticians can also polish or bevel lens edges so whatever edge does show looks clean and finished rather than white and chunky.

When contacts or other options make sense

Glasses are not the only answer for a strong prescription. Contact lenses sit right on the eye, so they avoid the magnifying or shrinking effect of thick lenses and give a wider, more natural field of view. For eyes with irregular corneas, such as keratoconus, scleral and specialty contact lenses often give sharper vision than any pair of glasses. Many people with strong prescriptions keep one great pair of glasses for evenings and use contacts during the day.

For children whose prescriptions climb every year, the best long-term strategy is to slow that climb. Our myopia management program uses ortho-K, myopia-control contact lenses and low-dose atropine, and our article taking a closer look at myopia explains why it matters.

A strong prescription also means a closer look at eye health

The American Academy of Ophthalmology defines high myopia as more than 6 diopters of nearsightedness. Eyes with high myopia are longer than average, which stretches the retina and raises the lifetime risk of retinal detachment, glaucoma and cataracts. That does not mean something is wrong today. It does mean a yearly dilated exam with retinal imaging is worth keeping on the calendar. You can see the instruments we use on our eye exam technology page. If you ever notice a sudden shower of new floaters, flashes of light or a curtain over part of your vision, read our guide to new floaters and flashes and call us the same day.

How we fit strong prescriptions at Reimbold Eye Group

A great pair of glasses for a strong prescription starts with an accurate exam. Our eye doctors refine your prescription, and our opticians then help you choose a frame that suits your face and your lenses, take digital measurements of where your eyes sit in that frame, and recommend the material and design that will give you the thinnest, clearest result. Bring your current glasses and we will show you where the thickness comes from and how much a different frame or lens could change it.

Questions we hear about strong prescriptions

What is the thinnest lens for a strong prescription?

Among plastic lenses, 1.74 high-index is the thinnest material in common use, followed by 1.67. An aspheric design and a smaller, rounder frame often save as much thickness as the material does, so the best result comes from choosing all three together.

Are high-index lenses worth it for a mild prescription?

Usually not. Below about plus or minus 2.00, standard plastic, Trivex or polycarbonate lenses are already fairly thin, and the extra reflections and color fringing of the highest-index materials are not worth it. We match the material to your prescription and frame rather than defaulting to the most expensive option.

Can I wear rimless glasses with a strong prescription?

Sometimes. Rimless and drilled frames show the full edge of the lens, so with a strong minus prescription the thickness is on display. Drilled mounts also need a tough material such as Trivex or polycarbonate, and 1.74 lenses are generally not recommended for drilling. A full-rim frame with a slightly thicker front usually hides the edge best.

Why do my eyes look smaller in my glasses?

Lenses for nearsightedness are minus lenses, and they make the eyes behind them look a little smaller. The stronger the prescription and the farther the lens sits from your eyes, the bigger the effect. Aspheric lenses, frames that sit close to the face and contact lenses all reduce it.

Does a strong prescription mean my eyes are unhealthy?

Not by itself, but high nearsightedness (more than 6 diopters) raises the risk of retinal detachment, glaucoma and cataracts later in life. That is why we recommend a yearly dilated exam and want you to call right away about sudden new floaters, flashes or a shadow in your vision.

Visit us in Alpharetta

Tired of thick lenses or heavy frames? Book online or call 770-776-9000 to schedule an eye exam and frame fitting. Reimbold Eye Group is at 4180 Old Milton Pkwy 1-D, Alpharetta, GA 30005.