What affect the thickness of glasses lenses?
People wearing prescription glasses get excited by the mere fact of choosing a new frame for their lenses. It's what most people focus on. But some also have to consider the thickness of the lenses. You might be one of those complaining about having thick prescription glasses. To understand why these thick lenses exist, one needs to know about the refractive index, frame size, pupillary distance, and prescription value.
1. Lens index
The lens index refers to the number representing the refractive power of the material of the lens, which generally determines the lens thickness. In some cases, materials, specifically those used in high index lenses, bend light more efficiently. Additionally, high index lenses have stronger corrections without using thicker lenses. You might have noticed that while your eye prescription increases, the lenses get thicker and heavier. Lens indices can either be 1.5, 1.57, 1.59, 1.6, 1.6, or 1.74.
2. Frame size
Frame choice is also essential, especially for those with a high-power prescription. Suppose you opt for a larger frame size; the lens thickness also increases, utilizing the side part of the lens, which is the much thicker part. Therefore, the larger the frame you get, the thicker the turnout of the lens. In context, suppose you choose an oblong frame shape; the sides of the lens will look thicker. On the other hand, rounded lenses help bring some areas of the lens thickness down.
3. Prescription value
Like how lens index affects lens thickness, the stronger the prescription, the thicker the lens would be. Of course, you can decide to have thinner lenses through a higher lens index. However, it is also worth noting that it can be expensive.
4. PD (Pupil Distance)
Some people call it a pupillary distance which refers to the distance between the center of two pupils. The optical center should align with the pupillary center to optimize vision and minimize distortion. To put it, thinner lenses mean that the pupillary distance is wider. Remember that whatever pupillary distance you have, it does not have a bad or good effect. It is just a mere measurement that basically depends on a person’s eye and face size.
How to buy the right frame based on lens thickness?
You always have the freedom to choose which frame style to buy for your eyeglasses. However, for your guidance and considering the lens thickness, you might consider these tips before buying one.
1. Opt for smaller frames. If you are expecting thick lenses, avoid large rectangular glasses frames, especially those with sharp angular edges. Smaller, oval frames are an excellent choice as they help reduce distortion and thickness, which are usually seen at the edges when using larger frames.
2. Rounder frames can help disguise stronger prescriptions. Several round glasses frames come with smaller lens widths. This means that the lens will look thinner. Remember that wider lenses result in lenses sticking out and being noticeable.
3. Plastic frames are better than metal ones. Thicker plastic frames allow you to hide the lens thickness better. Additionally, not much of the lens will stick out with plastic frames.
4. Avoid using frames that are rimless and semi-rimless. Thicker frames are usually better suited with thicker lenses. With this, you may want to avoid frames with little to no rim as they make thicker lenses more noticeable.
Simple care tips for glasses
Taking care of your frames also means ensuring the prescription lenses are in good condition. There might be some lenses that you can generally afford to buy more than once. However, in some cases, prescription lenses can be expensive. Hence it would be best if you put extra care into them.
When not in use, ensure to place glasses inside the case to prevent damage to the lenses and frame. Also, before wiping the lenses, it is advisable to rinse them with tap water. Rinsing the lenses will help you eliminate particles that might cause scratches.
More importantly, wipe the lenses with the cloth that came with your glasses. Using paper products, shirts, and handkerchiefs may trap abrasive particles which scratch the lenses. You may ask your eye doctor for a cloth replacement if you accidentally lost it.