Correcting Refractory Errors with Glasses
Refractory errors occur when light entering the eye isn’t focused correctly on the retina, resulting in blurred or hazy vision. The good news is that refractory errors can be corrected with glasses or contact lenses. In this article, we’ll explore the different types of lenses and coatings available for glasses.
Types of Lenses
There are two main types of lenses for glasses:
1. Single Vision Lenses: These lenses correct vision for one distance only. People with myopia (nearsightedness) need concave lenses, while those with hyperopia (farsightedness) need convex lenses.
2. Multifocal Lenses: These lenses correct vision for multiple distances. There are several types of multifocal lenses, including:
– Bifocal Lenses: These lenses have two different corrections, one for near vision and one for far vision.
– Trifocal Lenses: These lenses have three different corrections, one for near vision, one for intermediate vision, and one for far vision.
– Progressive Lenses: These lenses are similar to bifocal lenses but have a smooth transition between corrections.
– Computer Glasses: These lenses are designed specifically for computer use and have a correction for intermediate vision.
Materials Used for Making Lenses
Glasses lenses can be made from various materials, including:
– Glass: While glass lenses are still available, they are less common due to their weight and potential for breakage.
– Plastic: Plastic lenses are lightweight, flexible, and safe. They can also block UV rays.
– Polycarbonate: These lenses are recommended for people who are physically active, as they are impact-resistant.
– Trivex: These lenses are similar to polycarbonate lenses but have less distortion.
– High Index: These lenses are thin, lightweight, and recommended for people who require high visual correction.
Protective Coatings for Lenses
Opticians often offer protective coatings for lenses, including:
– Anti-Reflective Coatings: These coatings reduce glare and reflection, making it easier to drive at night and read small print.
– Ultraviolet Coatings: These coatings protect your eyes from UV radiation.
– Photochromatic Coatings: These coatings change tint in response to light, providing convenience for people who can’t wear sunglasses.
By understanding the different types of lenses and coatings available, you can make informed decisions about your eye care needs.