When selecting new glasses, choosing what lenses will work best for you is a major part of the discussion that you will have with the optician or optometric assistant prior to placing your order. Your optician will help identify what specific tasks, activities and environments you will typically be using your glasses in and will best determine which lenses will work best for your visual needs and lifestyle. When needing specific correction, such as a need for reading glasses or a reading prescription, patients have many different options available to them.
Progressive glasses are the most popular lens choice for people who require reading glasses. These lenses have the distance prescription ground into the top portion of the lenses with a gradual change / increase in power towards the bottom of the lenses for reading. These lenses do have some peripheral distortion where the powers are blended.
A progressive lens lets the patient see at all distances. They consist of a multitude of powers to let the patient see at whatever distance is needed. The great thing is these lenses do not have any visual lines and look like a regular single vision lens.
Most people enjoy their vision through progressive lenses as well as like the cosmetic advantage over visible line bifocals and trifocals that the lens provides. For people between the age of 40-50 who need vision correction, these lenses are usually the lens of choice, gradually making lined bifocal and trifocal eyeglasses a thing of the past.
Single Vision Eyeglasses: Reading Glasses
Reading glasses are just the near vision prescription placed into a pair of glasses. The entire lenses give the wearer a full field of vision. This lens is typically prescribed to be used for viewing 18 inches or closer. As well as having custom made reading glasses available, there are ready made readers that are available over the counter. Over the counter readers are a one size fits all type of glasses. They don’t necessarily work for everyone. People that have different prescriptions between their eyes, need a correction for astigmatism, or have wider or narrower set eyes then the average person may not be able to use this type of eyeglass. In cases like this, using ready made readers may cause headaches and eyestrain. For people who are able to comfortably use ready made readers, they are great option for helping out in a pinch. They allow for readers to be left in every room in the house, so you have something readily available to slip on when needed.
Custom made reading glasses are eyeglasses that are tailored to a person’s individual prescription as well as they take into account specific measurements, such as how a frame fits the person and how the lenses sit in front of the wearers eyes. Because they are customized to the wearer, they help reduce eye fatigue and eye strain.
If a person needs distance correction as well as reading correction, they may need a separate pair of eyeglasses that just correct their distance vision.
Task Specific Eyeglasses
Task specific glasses are glasses that are a specific prescription for a dedicated task. They are usually full field lenses (the whole lens). When adjusting an eyeglass for a specific task, the optician or optometrist will take into the account the distance at which the task will be performed or viewed, the prescription will then be customized to allow for optimum viewing at that distance. Computer glasses are probably one of the most common types of task specific eyewear, this is because computer screens are often viewed at a different distance then regular reading material. Many people who quilt or cross-stitch also may benefit from using a task specific lens.
Bifocal lenses consist of two prescriptions. This lens has a visible line that seperates the different powers from each other. They consist of a reading prescription in the bottom of the lens with the distance correction being in the top. The reading area of correction in most bifocals look like a “D” turned on it’s side. The reading prescription is usually used for reading things that are approximately 18 inches and closer. The distance prescription is situated in the top part of the lens and is used for objects 21 inches away and further. Because of advancements in technology with progressive lenses, bifocals are becoming less common.
Trifocal glasses consist of three areas of vision. Like bifocal glasses, they have a visible line that separates the distance, intermediate and reading prescriptions. Just like the bifocal lenses, these lenses have an area within them that look like a “D” turned on it’s side. The difference between trifocal lenses and bifocal lenses is an area of intermediate vision (usually a computer distance) that lies just above the reading prescription giving the wearer another field of vision for an intermediate focal length. Like bifocal glasses, these glasses are declining in popularity.
In the future, when selecting new glasses to help with reading, make sure you understand all your options. As well, by discussing what activities your do on a day to day basis with your optician, it will help make sure that the lens design being chosen for you will accommodate most areas of your lifestyle. This will enable you to have best visual experience possible.
Article Written By: Karen McAulay