How can I help someone with a learning disability understand their eyesight prescription?
Everyone's prescription is different. The abbreviations and numbers used by optometrists when writing a prescription can be difficult to understand. It's important to use simple and clear language and the optometrist will also be able to help explain what the prescription means. Here are some of the most commonly used terms:
R: right eye
L: left eye
sph or sphere: the number for how long sighted (hyperopic) or short sighted (myopic) you are.
- A plus/positive number means you are long sighted (hyperopic)
- A negative/minus number shows you are myopic (short sighted).
cyl or cylinder: this describes the shape of your eye. It measures how oval your eye is, which indicates how much astigmatism you have. Astigmatism is when your eye is oval or rugby ball shaped, rather than round. Most people have a small amount of astigmatism, which they may not be aware of. The cyl can be a plus or minus number depending on how the optometrist chooses to write it down. The larger the number, the more astigmatism you have.
axis: this is always a number between 0 and 180 and describes the angle (in degrees) at which the astigmatism is. It is important for the person who is making up the glasses to know the axis.
prism: where the front and back surfaces of the glasses lens are designed so they are inclined at an angle to one another. This helps both eyes to work together better if, for example, the person has a squint. base: the direction in which the prism is effective - up, down, in or out.
distance: a distance prescription should be used for watching TV, driving or any activities taking place at a few metres distance. Some people may wear this prescription all the time and may not need a different prescription for other activities.
near: a near prescription should be used for close work such as reading, ipad, phone or craft work carried out at a distance of 25-45 cm, (10-18 inches).
intermediate: this describes a prescription for work at any distance from 40 cm to 1m (16 to 40 inches), including hobbies like woodwork or using a computer, or using eye tracking software.
add or addition: the part of the prescription added on to the distance prescription to give the near or intermediate prescription. It is always written as a positive number and is usually in the range +0.75 to +4.00. Some people with poor vision may need a stronger add, this may mean that they need to hold their reading or craft work closer to their eyes to see it clearly in focus.
Further information in an easy read format on understanding prescriptions and choosing the best glasses can be found on the SeeAbility website.
