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After an eye exam you will receive an eyeglass Rx which can be used to purchase eyeglasses
Your eyeglass Rx will be valid for 2 years
Patients under 20 years old (who need eyeglasses to see clearly) should measure a new eyeglass Rx every year
Type of Lenses
Type of Lenses
If you are over 43 years old and you want:
One pair of glasses to see both far away and close up, you will need either a lined bifocal or a progressive lens
One pair of glasses to see far away and a different pair to see close up you can purchase separate glasses for far away or close up
If you are under 43 years old, one pair of glasses will work for far away and close up
Using the wrong strength glasses can cause permanent developmental problems only for children under 12 years old
Types of Progressives
Types of Progressives
There are different levels of quality of progressive lenses
Patients with a high strength Rx will usually do better with a high quality progressive lens
If you try a high quality progressive lens and you cannot get used to them, consider a lined bifocal
If you try a low quality progressive lens and you cannot get used to them, consider a high quality progressive lens
Lens Materials
Lens Materials
Different grades of plastic will have different weights and different thickness for a given Rx
The higher the lens index, the thinner and lighter the lenses will be
Patients with a high strength Rx will usually do better with a high index material
Patients with a low strength Rx will usually do fine with the standard plastic lens
Patients with a big difference in Rx between the two eyes will do better with a high index material
Patients under 18 years old will need polycarbonate material for safety reasons
Another way to make your lenses thin is to choose a frame that is small, so the lens inside will be small
Some farmers like glass lenses because they will not scratch as easily as plastic
Antireflective Coatings or Antiglare Coatings
Antireflective Coatings or Antiglare Coatings
The purpose is to reduce glare in your vision and to prevent the lenses from reflecting overhead lights when someone else is looking at your eyes through your lenses
The ARC is usually the first thing to wear out on a pair of glasses
Lenses look scratched or crazed
This cannot be fixed, the lenses need to be replaced
High quality ARC might come with a 2 year warranty
Low quality ARC might only last 6 months
Blue blocking ARC will limit the amount of blue light into your eyes from your computer screen
This might reduce eye strain or fatigue from hours on the computer
Evidence we have on blue-blocking glasses says they don’t work
Blue-blocking lenses have no effect on eyestrain despite them being specifically marketed for that purpose
https://www.scientificamerican.com/article/do-blue-light-glasses-help-with-eyestrain/
Sunglasses
Sunglasses
Sunglasses are for comfort in bright light environments
Protecting the eye from damaging UV rays can be done with clear UV coatings
You can tint your lenses with dye any color or darkness that you would like
You can get a polarized lens which will selectively block reflected light (from sun to water to eye)
These lenses can be purchased in brown or gray
These lenses might make images on your phone screen disappear when viewed at certain angles
Transition (photochromic) lenses can automatically change tint when you walk from a dark to bright environment
The lenses are not as clear as a regular clear lens and they are not as dark as typical sunglasses
The lenses will not work in the car because your windshield blocks the UV and the UV is what triggers the automatic tint
Drivewear lenses change from a light yellow in dim lighting to a darker brown in bright lighting
These Transition lenses do work in the car, since light is what causes the lenses to automatically tint
Other options include magnet or clip attachments to put over your clear glasses to transform them into prescription sunglasses
Anatomy of an Eyeglass Rx
Anatomy of an Eyeglass Rx
Each eye has its own Rx
The right eye is labeled OD (oculus dexter, Latin for right eye) and the left eye is labeled OS (oculus sinister, Latin for left eye)
The sphere (SPH) number in each eye gives the amount of myopia or hyperopia
It is important to include if the sphere is plus (+) or minus (-) power
Sometimes this is written as Plano (PL) when the sphere number is +0.00
The cylinder (CYL) number in each eye gives the amount of astigmatism
It will be blank or 0.00 if you have no astigmatism
It is important to include if the cylinder is plus (+) or minus (-) power
The cylinder axis (AXIS) in each eye gives the angle (or the rotation) of the astigmatism
This number ranges from 001 to 180
It will be blank or 0 if you have no astigmatism
The ADD power is usually the same in the two eyes and it gives the difference in power between the distance and near Rx
If you have an ADD power, then you have the option to get a progressive, lined bifocal or separate distance and near Rx glasses
The interpupillary distance (IPD or PD) measures the distance between the center of your two eyes in millimeters and for most people this is close to 63 mm
The accuracy of this number becomes more important as the eyeglass prescription is higher and higher (plus or minus)
Symptoms for an inaccurate PD include: headaches, strain, or double vision
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