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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.
Have you ever seen a temporary black spot in your vision? How about jagged white lines? Something that looks like heat waves shimmering in your peripheral vision?
If you have, you may have been experiencing what is known as an ocular migraine. Ocular migraines occur when blood vessels spasm in the visual center of the brain (the occipital lobe) or the retina.
These optical migraines can take on several different symptoms, but they typically last only from a few minutes to an hour. They can take on either positive or negative visual symptoms, meaning they can produce what looks like a black blocked-out area in your vision (negative symptom), or they can produce visual symptoms that you see but know aren’t really there, like heat waves or jagged white lines that look almost like lightning streaks (positive symptoms).
Some people do get a headache after the visual symptoms but most do not. They get the visual symptoms, which resolve on their own in under an hour, and then generally just feel slightly out of sorts after the episode but don’t get a significant headache. The majority of episodes last about 20 minutes but can go on for an hour. The hallmark of this problem is that once the visual phenomenon resolves the vision returns completely back to normal with no residual change or defect.
If you have this happen for the first time it can be scary and it is a good idea to have a
