Choosing Glasses for Your Child – Lens, Materials

Warranties

Warranties can be a life saver for many families. Glasses – especially glasses worn by children – can be broken, lost, or damaged easily, and they need to be replaced. Many children have frequent prescription changes, especially in the first couple of years of getting glasses. Different shops offer different warranties and some frames and lens options come with warranties as well. Make sure you completely understand the warranties are available to you and what they do and do not cover before deciding if any of them will be worth the cost.

• Frame warranty: Some frame warranties only cover manufacturer defects, others will cover all damage, no matter what caused it. A few warranties cover frames being lost.
  
• Lens warranty: Lenses can get scratched very easily, even if they have an anti-scratch coating. In fact, many anti-scratch coatings automatically come with a warranty against scratches.
• Prescription warranty: Many optical shops will offer a short-term warranty for prescription changes.
  

Lens options

There are a lot of options when it comes to lenses. The choices can affect the weight, the thickness, the image that your child sees through the lenses, the look of the glasses, and the price. Not all options are available at all shops and for all prescriptions.

Prescription
A higher prescription will mean thicker lenses.

• Prescriptions for hyperopia (farsightedness / longsightedness) will have the thickest point in the middle of the lens
  
• Prescriptions for myopia (nearsightedness / shortsightedness) will have the thickest point on the edges of the lens.
  

Materials
Polycarbonate and Trivex are the most commonly used materials for children’s glasses. This is because both are highly impact-resistant and offer full UVA/UVB protection. Polycarbonate lenses are thinner than Trivex for the same prescription, but Trivex is a lighter material. Since Trivex lenses will be a little thicker, there is not much difference in weight between the two for the same prescription.

There are also other materials with a higher index than Trivex or Polycarbonate. The higher the index, the thinner the lens. While high-index materials are less impact-resistant than Trivex and Polycarbonate, they are still impact-resistant and may be more appropriate for children with very high prescriptions. This is a question you should discuss with the optician.

Lens Curve
Traditionally-cut lenses will have steep curves for higher prescriptions. Aspheric lenses are cut so that they have a less steep curve, and so are thinner for the same prescription. They are particularly recommended for high hyperopic prescriptions.

Other options

• Scratch-resistant coating: Some lens materials (Polycarbonate in particular) are soft and prone to being scratched easily. A scratch-resistant coating will help prevent some scratches. Lenses with scratch-resistant coatings are not scratch proof and can still be scratched.
• Anti-reflective coating: Also known as “anti-glare coating”. This coating will reduce the reflection of light from the outside of the lenses (that’s what causes glare on lenses).
• Photochromic coating: Often referred to as “Transitions” which is a brand name of this type of coating. Photochromic lenses will darken in the sunlight. Most photochromic coatings will not darken in cars, but some do.

Adapted from Toddler Glasses
photos: For Little Eyes