Glaucoma Exam

What does a glaucoma examination involve? What should I expect during a glaucoma exam?

First of all, it is really important to know about your general health. We will give you questionnaire and ask about all your heath problems you have now or had in the past. We need to know what surgeries you have had including eye surgery and full list of medications including herbal remedies. If you have copies of any test that may have been performed, that is helpful also for your physician.
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Eye exam begin with a vision and glasses check. We try to evaluate your side vision manually but this is not a conclusive test for glaucoma. Your pressure is measured after putting a numbing drop mixed with yellow stain to enhance the physician’s visualization under a purple light. This is the standard test for glaucoma. Sometimes just a “pen like” instrument is used or an instrument that puffs air on your eye is another example of tests for glaucoma. The thickness of your cornea, the very front, clear part of your eye, is also checked. Thickness of the cornea affects the pressure readings, and it may cause false high or low readings. For this purpose, an instrument, called pachymeter will be used after using the numbing drop on your eyes. It takes usually 5 minutes each eye. (Figure 1)

Figure 1: One of the commercially available ultrasonic pachymeter.

Your eyes are then dilated. The doctor will determine if you have any other diseases such as cataract and macular degeneration and examine the optic nerve in great detail.

Figure 2: Some of the special lenses used for glaucoma exam

Also, a special lens will be used to see if the angles (where the drainage of fluid in the eyes occurs) in the eye are normal, narrow or closed. (Figure 2)

Figure 3 and 4: Examiner is looking at the back of the eye with the aid of a hand held lens. The lens is placed in front of the eye but not touching the eye. You can blink at this point but you will be asked to look steadily in a certain direction.

When the nerve is examined, your nerve might look like one of the photos below. (Figures 5-8)

Figure 5. Fairly normal looking nerve

 
Figure 6a. Slightly suspicious looking nerve. 


 
Figure 6b. The larger white circle shows the margins of nerve; the smaller circle points to the margins of “cup,” the area that has no nerve. The larger the “cup,” the more suspicious it is that glaucoma may be present.


Figure 7. Suspicious looking nerve with large “cup.”

Figure 8. Clearly the “cup” area is very large.
This patient very likely has glaucoma.

We will take the picture of the back of the eye from time to time to document what is seen in the exam. This information will be in your records and will be available for review and comparison in future.

To confirm the diagnosis, we will schedule you for visual field test. A visual field test is one of the diagnostic tests for glaucoma. It is also used to monitor the progression of the disease. It takes 10-15 minutes or less for each eye. The patient’s response also determines the length of the test. We may need to repeat it fairly often if it is not reliable or if it seems to be progressing.

Figure 9. A patient is positioned at the visual field machine.

Figure 10.A visual field will look like this if it is normal. Each dot represents the location of the blinking lights for to the patient to see.

We may need to do additional testing to further confirm the glaucoma. One of the fairly new test we use in glaucoma is called OCT (optical coherence tomography). It is a computerized, high-technology test that provides information about the nerve and surrounding layers.

 
Figure 11. During an OCT test

Figure 12. Black line (information from patient’s eye) in this graph falls into normal zone (green zone).

Figure 13. On this graph, we see a drop in black line to the red zone. This implies decreased nerve thickness.

Figure 14.  The patient above also had corresponding visual field defects as shown here. The areas cannot be seen by the patient are in dark black squares.

Figure 15. The OCT shows advanced loss of nerve layer.

Figure 16. Visual field test of the very same patient in Figure 15 also shows advanced field loss.

Overall the visual field and OCT are complimentary to each other.

This section was designed to summarize a general glaucoma exam and testing. However, every patient is different and needs a different approach rather than a routine exam and testing. It is most important for the patient to ask your doctor to discuss the results of the tests and how these results will affect his/her treatment plan.

Prepared by Inci Irak Dersu, MD
Thanks to the many JEI patients who inspired the author to create this reference document.