Page 40 - The Book Pi in eye

Rajesh Khanna, MD

also measure the shape and some other variables.
 Ultrasound Biometry (A-Scan)- An ultrasound or high
frequency sound wave to measure the length of the eye.
This is similar to the sonar system used by bats.

Corneal Pachymetry:
Measures the thickness of the cornea: can be determined by
ultrasound or non-contact optical method: also can help to detect
abnormal corneas.

Figure 5.2 Pachymetry map of cornea

Refraction:
If your vision is not 20/20, then your doctor will conduct the
appropriate test to detect the abnormality in your vision. If you’ve had
a previous eye exam, then you may be familiar with the steps needed
for corrected vision.
Your doctor can use an auto refraction device, which captures
refracted light from the retina. A print out with the approximate
prescription is generated, than a phoropter, which has a range of
lenses, is employed and your doctor will obtain the best correction
and prescription for you.

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