Glaucoma Diagnosis and Humphrey-Zeiss FDT Computerized Visual Field Monitoring


The most common form of glaucoma affects vision very quietly. There is no pain or redness and vision is usually excellent in the early stages of the disease, which can last for years. It takes away the "edges" of vision so very gradually that this is not noted by the patient until severe irreparable damage has been done. The chances of having glaucoma increases with age.

The chances of having undiagnosed glaucoma rise sharply after  the late 30's, so a pressure check is carried out as a routine in anyone over the age of 38 as a routine.

It is known as 'The silent thief of vision', as it causes no symptoms in its early stages, and by the time that a person notes changes in vision, the damage is irreversible. To begin to diagnose glaucoma, a careful medical history is taken (part of every routine medical eye examination), and risk factors are noted by the doctor. Often a glaucoma patient will report that they have older family members with the same diagnosis.

The intraocular pressure is then taken. In the Al Basil Eye Clinic, we use a Tonopen measuring device after putting in a numbing eye drop. This device is gentle (there is no puff of air)  and completely painless. We are able to check the eye pressure of even small children who are at risk for glaucoma.


The corneal thickness is measured using an ultrasonic unit the Corneo-Gauge Plus. Thickness of the cornea is now documented as both an independent risk factor as well as an error-inducing measurement factor. The true pressure of the eye can be as much as 5mmHg lower or 3mm higher than what is measured, depending on corneal thickness.


The optic disc is then carefully examined. This is the area where the optic nerve enters the eyeball, and is the part that is damaged by high pressures. Examination of the optic disc requires experience and training, as early changes can be quite subtle.

If the pressure and disc appearance alert the clinician to the presence of possible or definite glaucoma, a computerized visual field analysis is then later performed.

This allows for early detection of any variations from normal. 

Testing with our new Humphrey-Zeiss ZEST testing algorithm unit is quick, painless and far less tiring for the patient than older techniques.

A screening test takes less than a minute whereas a detailed examination of an abnormal optic nerve head function takes about 5 minutes per eye. Older units used to take up to 20 minutes per eye and would be extremely tiring for the patient.

In addition this newer method of testing using FDT technology is far more sensitive to early glaucoma damage than other available units. The earlier the diagnosis and treatment, the better the results in caring for this condition.

Statistical analysis software allows more careful monitoring over months to years, allowing finer adjustment of the control of a case. This is far more scientific, exact and precise than simply monitoring approximate directly-measured pressure and disc changes alone, as the changes can be very slow and subtle.

Often pressure control can be achieved with the use of eye drops alone, preventing further damage. The earlier the diagnosis is made and treatment started, the better the prognosis.

In the cases that do not respond to the correct choice of eye drops, other options that may be required are laser treatment or surgery both of which are readily available for indicated cases.



Clinic 2,
Building 159, Palace Avenue,
Block 318, Hoora.

Tel. 17-310030