Strabismus Measurements
What is strabismus and HOW do we check for it?
Strabismus is when the eyes are not pointing in the same direction, There are different ways to measure how much the eyes are crossed or drifted. These are:
- Where the light shines on eyes
- Cover one eye at a time
- Special testing with prisms, special glasses, and a synoptophore machine (a device that checks how well the eyes work together).
These tests help us check on the strabismus and if treatments are working.
WHAT does shining a light on the eye test?
In the light test, the doctor (ophthalmologist) shines a light on the eyes. They look at how the light bounces off each eye. If the light does not look the same in both eyes, it may mean that the eyes are crossed or drifted. A prism can be used with a light test to better show how much the eyes cross or drift. The light test is good for young kids and people can’t see well.
WHAT IS COVER TESTING?
In cover testing, you or your child look at something small. The doctor covers one eye at a time. The doctor watches how the eyes move when they are covered and uncovered. If the eyes move, it might mean that they are crossed or drift. A prism can be used with the cover test to help who how much the eyes cross or drift.
WHAT ARE PRISMS?
Prisms are clear, triangle-shaped tools. They bend light. When you hold a prism in front of an eye, it moves the light. Bigger prisms move the light more. Prisms help doctors measure how much eyes are crossed or drifted.
WHAT if eyes look crossed but aren’t?
Sometimes eyes can look crossed but really aren’t. This can happen because
- The light doesn’t focus in the center of the eye (positive angle kappa)
- The nose bridge is wide (pseudostrabismus)
The doctor (ophthalmologist) can tell if the eyes are really crossed or drifted with tests.
WHY do we need GOOD MEASUREMENTS for eye crossing and drifting?
Good measurements help the eye doctor (ophthalmologist):
- Choose the best treatment
- See if the treatment is working
Sometimes a few doctor visits are needed to get the best measurements. Eye doctors (ophthalmologists) can’t check for eye crossing or drifting when you or your child are asleep.
Updated 06/2024
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