Ocular biometry – IOL Master

Medical content revised by - Last revision 02/02/2021
Ocular biometry – IOL Master

What is IOL Master ocular biometry?

The IOL Master ocular biometry is a test that measures the size of the eyeball, called axial length, and allows to calculate the dioptric power of the intraocular lenses that are implanted at the end of the crystalline lens, which is the inner lens of the eye that helps to focus better.  Lens extraction is performed in cataract surgery or refractive surgery, so ocular biometry is a necessary test for any patient who is a candidate for either of these two surgeries.


What is it used for

The results obtained through biometry are not used to detect a pathology, but are important to complete the study prior to cataract surgery or refractive surgery, as well as to follow up patients with progressive myopia, since the increase in myopia is associated in many cases with an increase in ocular size and therefore in its axial length.


Before the test

The IOL Master ocular biometry does not require any particular prior preparation or pupillary dilation, but it is necessary to perform the test without contact lenses. For this reason, it is recommended to stop using them 24 to 48 hours before the test.


After the test

The IOL Master ocular biometry is a non-invasive technique, so it does not require direct contact with the eye and does not cause adverse reactions. After the test, therefore, it is possible to carry out any day-to-day activity without any problem.


How is it done

The examination is performed using a biometer in a seated position and without physical contact at eye level. With the chin set and the forehead leaning forward, the patient has to fix the gaze on a central light pattern inside the device without moving the eyes or the head.

It is a test that lasts only a few seconds and is performed by an optometrist. Once the results are collected, the ophthalmologist will be in charge of analyzing and interpreting the results and evaluating them with the patient during the visit.


Biometría IOL Master

Biometrical Values


Frequently Asked Questions

Does it cause any kind of discomfort?

No, as it is a non-invasive technique, it does not contact the eye, so it does not cause any kind of discomfort.

Do I have to be accompanied?

No, this test does not require you to be accompanied by another person.

Should I go fasting?

It is not necessary to come fasting for the test.

How long does it take to obtain the test results?

The results are obtained at the same time as the test is performed.

Can the optometrist evaluate the test result at the time of the test?

No. The optometrist is the one in charge of the test and has the knowledge to confirm its correct execution. It is the ophthalmologist who has to evaluate and report the results obtained, who will do so in the clinical context after a complete history and examination of the patient.

Is it possible to drive after the test? And can I take a shower?

Yes, after the test it is possible to carry out any day-to-day activity, such as driving or showering.

Is it possible to use make-up after the test?

Yes, there is no inconvenience in using make-up after this test.

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