Biometry

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Biometry

Duration:

15 minutes

Pre-test Instructions:

  • Do not wear contact lenses for 48 hours beforehand.

What is it?

Ocular biometry is a test that measures various dimensions of the eye, including:

  • Axial Length: The distance between the anterior and posterior parts of the eye.
  • Depth of the Anterior Chamber: The space between the cornea, iris, and lens.
  • Corneal Thickness, Curvature, and Diameter: Measurements of the cornea's shape and size.

This test is particularly essential in determining the precise dimensions of the eye for the implantation of an intraocular lens (IOL), such as in cataract surgery. Accurate measurements are critical for selecting the right IOL to ensure optimal vision post-surgery.

How is it performed?

Ocular biometry can be performed using two primary techniques:

  1. Ultrasound Biometry:

    • Uses sound waves emitted into the cornea.
    • Requires contact with the cornea and local anaesthesia.
    • This technique is more invasive and takes longer to perform.

  2. IOL MASTER Optical Biometry:

    • Utilizes infra-red laser light.
    • Non-invasive and painless, with no need for anaesthetic or dilating drops.
    • This method is the most commonly used today, providing more precise results in most cases, except in patients with very opaque lenses.

4 Key Facts About Biometry:

  1. Painless Test: No discomfort during the procedure.
  2. No Pupil Dilation Needed: Dilation of the pupil is unnecessary.
  3. Contact Lenses: Ensure to avoid wearing contact lenses for 48 hours before the test.
  4. Test Duration: The procedure takes approximately 15 minutes.

What Diseases Can Be Diagnosed?

Biometry is essential for the following:

  • Cataract Surgery: Helps determine the right intraocular lens (IOL) for replacing the eye's natural lens.
  • Presbyopia Surgery: Used to calculate the lens to replace the aging natural lens.
  • Refractive Surgery: Important for surgeries correcting myopia, hyperopia, and astigmatism with Phakic lenses, which do not replace the natural lens but help correct vision.

Associated Pathologies

  • Cataracts: Required for cataract surgery to select the proper IOL.
  • Myopia, Hyperopia, Astigmatism: Used in refractive surgery planning, especially with Phakic lenses.
  • Presbyopia: Necessary for planning surgery to address age-related near-vision loss.

Associated Treatments

  1. Cataract Surgery: Involves replacing the eye's natural lens with an IOL.
  2. Refractive Surgery with Intraocular Lenses: To correct vision defects like myopia, hyperopia, and astigmatism using lenses.