The eye is one of the most specialized organs of the human body. Diagnosis and monitoring of eye diseases cannot be achieved without the use of additional tests. In the list below, we point out the reason why we do some of these tests, what you can expect and the time required. Note that this is not a complete list of tests, not even a complete list for our office. It covers only the most common ones you may encounter.

OCT (Optical Coherence Tomography)

OCT gives us a detailed view of the retina by just looking into a machine! The retina is the seeing part of the eye, and at its center the macula allows you to read and recognize faces. It is this area which we most often look at. The high magnification which this machine provides allows us to see details we cannot see with the standard examination of the eye using the slit lamp or the indirect ophthalmoscope. Under certain circumstances, we can also see the deeper layers of the eye, those under the retina called the choroid; or loot at the optic nerve and the nerve fibers from the retina.

To perform this examination, we will ask you to position yourself firmly in front of the machine, chin on the chinrest, and your forehead against the headrest. You need to look towards the center of the machine at a flickering light. It is important not to move the eye during measurement, and refrain as much as possible from blinking too much.

The exam takes between 5 to 10 minutes per eye. The pupil may need to be dilated to get good enough images.


In this exam, we measure the sensitivity to light of the retina within the fovea, the very center of the retina - the most sensitive part of your vision.  This is the area that allows the most accurate vision. It can loose part of its sensitivity due to several eye diseases. Microperimetry allows us to better understand and monitor this sensitive area for progression or recovery after therapy.

To perform this examination, we will ask you to position your head in front of the machine, chin on the chin rest, and your forehead against the headrest. You need to look towards the center of the machine. You will be given an actuator (a clicker). Each time you see a light flashing in front of your eye, you will be asked to depress the actuator to confirm that you saw the light. The position of the light and its intensity will vary throughout the test.

This exam may take up to 30 minutes per eye and requires good concentration.


This non-invasive procedure determines the degree of dispersion of the light as it passes through the eye toward the retina. The dispersion may be caused by the cornea, cataracts or floaters in the vitreous. Through this test, we can better quantify how badly light dispersion affects your vision.

For this test you will be asked to look into a device. At its center you will see a half flickering ring of light. You must indicate by way of a pushbutton switch on which side the flicker occurs. The test will take about 5 to 10 minutes per eye.

Autofluorescence and autoreflectance

The light reflected by the retina and the layers of the eye beyond  is more intense at certain wavelengths than at others. The analysis of the intensity of this light gives us some indication of the health of the retina and retinal pigmented epithelium under it. This test is particularly useful in monitoring patients with AMD and in various macular diseases.

A photo of the back of the eye is taken while you are fixating on a target. To obtain a sharper picture, an average of several images is obtained so it usually takes a minute or two to gain enough images per eye.  It is important not to blink while the test is being carried out.

Ultrasonography / UBM

It is not always possible to see the internal structures of the eye. It is sometimes necessary to use an ultrasound machine to see if the retina is intact or whether it is necessary to intervene surgically. Ultrasound works like a radar. It allows us to see the inner layers of the eye but requires a good experience to interpret the images.

The UBM is a high power ultrasound (Biomicroscopic). It is especially useful to analyze the structures around the ciliary body behind the iris.

You will be asked to close your eyelids lightly. A gel will be placed on the closed eyelids. The ultrasound probe is placed on the surface of the lid in different positions in order to analyze various planes of the retina and vitreous (the cavity in front of the eye). Sometimes it is necessary to place the probe directly in contact with the eye. If this is required, the eye will first be anesthetized properly before we proceed any further.

The test will take between 5 and 15 minutes depending on the complexity of the examination.

Fluorescein and indocyanine green angiography

Angiography is used to evaluate the blood vessels of the retina and the integrity of all retinal layers. Normally retinal vessels do not allow fluorescein or indocyanine green to leak out into the surrounding tissue. In certain eye diseases, leakage occurs. It is important to assess the degree of the leakage present. In other eye diseases, the vessels disappear or clog up. This is also something for which we require angiography to adequately assess.

In this test, the pupil needs to be as well dilated as possible. A venous access catheter will be placed in one of the veins of your forearm and after you have positioned your head confortably in the headrest, and we have been able to get good preliminary picture, the appropriate contrast agent will be injected through the catheter. A series of photos will be taken over a period of 30 minutes in one or two eyes. This procedure is well tolerated by nearly all people, but occasional, rare allergic reactions have been reported during angiography. It is therefore important to inform us if you have any allergies, or if you have had problems with angiography in the past. This test is rarely performed during pregnancy. Your doctor will describe in more detail why and how the test is carried out.

The exam takes about 45 minutes if you include both the preparation time and angiography itself. It  will take about an hour if the two  types of angiography are combined together.

OCT angiography

In the last few years, a new OCT technique has been developed called OCT angiography or OCTa. In this imaging approach, a retinal image taken at time t=0 is compared to with the same image taken a fraction of time later. If particles in the image, say red blood cells moved during the time interval, this will be perceived as a movement. Comparing the two images, it is possible to create a map of blood vessels (capillaries, arterioles and venules) in which blood circulated during the time interval. It is also possible to look at these at various planes in the retina. However, it is important that the circulation was at least as fast as the time interval, if the blood circulation was slower, it will not be perceived.

OCTa may be a good way of detecting some new abnormal vessels (as is seen in AMD), or loss of capillaires (as is the case in diabetes or some uveitis cases). The presence of anomalies is instructive, but their absence does not mean that they have not occurred - a current limitation of the technique. Hence OCTa does not replace traditional angiography techniques but does complement them handsomely.

We are equipped to perform OCTa and will use this technique to image the retina in patients where mapping the vascular supply of the retina and macula can be useful.