Published: 02 February 2023

Transition lenses in eyeglasses have been around for many years now. The mechanics behind transition lenses is that certain chemicals in the lens interact with UV light from the sun and turn the lenses dark when you go outside and back to clear when you go inside.

This is a great accompaniment to sunglasses, as it is not always convenient to be carrying around multiple pairs of glasses with you, especially when going from inside to outside frequently. However, there are some drawbacks to transitions, including the fact that they don’t get as dark as sunglasses, have some difficulty turning dark in the car, and have a tendency to keep a slight constant tint even in dark conditions.

Vistakon, the optical wing of Johnson & Johnson, came out with the first transition contact lens a few years ago.  They work well for some people, and don't seem to do a lot for others.

Just a couple personal thoughts: It can look a little strange, depending on the person and the eye color. The material itself turns gray, and therefore the person can be walking around with eyes that look darker than normal. On the plus side, though, this would be good for people limited by high prescriptions and who have difficulty with peripheral vision and glasses, yet still want the transitioning technology. On the other hand, wearing clear contact lenses with sunglasses would provide better sun coverage with the ability to remove the sunglasses when desired.

An area where transition contacts might become very useful is in outdoor sports.  For any athlete who is playing an outdoor sport where the lighting conditions may change from day to day or even within a single game or event, these contacts might significantly improve the ability to perform. This is especially true in any sport where there may be significant contact or rapid head movement that can make it difficult to compete in sunglasses.  

While still in its infancy, transitioning contact lenses look to be a promising technology.

Article contributed by Dr. Jonathan Gerard

Published: 05 January 2023

A common question asked during the eye exam is, “When is the puff coming?”  

Patients are referring to air-puff or non-contact tonometry. Tonometry is the procedure used to measure eye pressure, and this is important for diagnosing and monitoring glaucoma.

In non-contact tonometry, a puff of air is used to measure the pressure inside the eye.  The benefit of this test is there is no actual contact with the eye, but the air puff is sometimes very startling for patients. Some people hate that test and it isn’t the most accurate way to measure your eye pressure.

Some doctors don’t even use the air-puff test. Instead, they place a yellow drop that consists of a numbing medicine and then shine a blue light on the eye. This is done in front of the slit lamp and a small tip gently touches the eye to measure the eye pressure. This procedure is called Goldmann tonometry and is considered the gold standard for measuring eye pressure.  

Another method for checking eye pressure is the Tonopen. This is a portable, hand-held instrument that is useful when patients can’t sit in front of the slit lamp to have their eye pressure checked. The Tonopen also requires a numbing drop to be placed in the eye, and the tip gently touches the eye.

A common question related to tonometry is “what normal eye pressure?”

Normal eye pressure ranges from 10-21 mm Hg. Eye pressure doesn't have any relationship to blood pressure. Many times, people are surprised that their eye pressure is high, but they have normal blood pressure. In general, there is no diet or exercise that will significantly affect eye pressure. It is therefore important to have your eye pressure checked regularly because there are usually no symptoms of high eye pressure until it has affected your vision.

Article contributed by Dr. Jane Pan