Page 45 - The UK Guide to Laser Eye Surgery
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Questions about technology
45
 Pupillometry
What is it for?
Measuring your pupil size. The pupillometer measures the average pupil size, variation in pupil size over a fixed time frame, and difference in pupil size between the two eyes in three different light levels.
What actually happens?
You are positioned with both eyes viewing a spot light through padded eyepieces. The clinician then measures the size of each pupil in three different light levels, using an infrared camera.
How does it feel?
You feel nothing as the instrument does not make contact with your eye.
How does it benefit you?
Accurate pupillometry is crucial for successful laser eye surgery, because lasers are only capable of treating a defined area of the eye. Typically, this is a circle with a diameter of 6 mm to 8 mm, depending on the laser used. If your pupils were larger than the area that can be treated by the laser, you would be left with an untreated ring around the smaller circle corrected by the laser. It would be like looking through a clear patch in the middle of a smeared window. Some people with large pupils can only be treated by specific lasers that are capable of covering larger areas.
Secondly, some patients have an increased risk of experiencing night vision changes (such as halos and ‘starbursts’ around lights) after surgery. Accurate pupil size measurements for dark and dim lighting conditions allow your surgeon to optimise your treatment plan to minimise the risk of this occurring.























































































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