Glaucoma - Tonometry

Eye Health – Glaucoma (Part 5)

Dr S S Gill, Consultant Ophthalmologist, Hospital Fatimah Ipoh
Dr S S Gill, Consultant Ophthalmologist

In conjunction with World Glaucoma Awareness Week, Ipoh Echo talks to Consultant Eye Surgeon Dr S.S. Gill about this “silent thief of sight” – PART 5

Glaucoma as you know has been nicknamed the “silent thief of sight”. This disease results in permanent irreversible blindness in the affected eye(s) that often goes without symptoms until the loss of vision is significant or the patient is blind.

Early diagnosis means early treatment and therefore prevention of major loss of vision. Diagnosing glaucoma may require elaborate testing to be done by the eye doctor.

The following are basically the tests that are done before making a diagnosis of glaucoma:

Examination of:                                                            Name of Eye Test:

1. Eye Pressure                                                                     >Tonometry

2. Angle of the eye where the aqueous (eye fluid) drains      >Gonioscopy

3. Optic Nerve check                                                              >Ophthalmoscopy (dilated eye exam)

4. Field of Vision                                                                     >Perimetry

5. Thickness of the Optic Nerve Fibre Layer                         >Ocular Coherence Tomography Scan

1. Tonometry

Glaucoma - TonometryThis is the measurement of the eye pressure (intraocular pressure or IOP). This is often the first test that is done. If a person has higher than normal eye pressure, it would mean that the person would have a higher

risk for glaucoma. It is important to understand that having eye pressure higher than normal does not mean a definite diagnosis of glaucoma.

The test is done by first instilling some eyedrops to numb the eye. Following that, the eye pressure (IOP) will be measured using a Goldmann tonometer. Sometimes an air-puff tonometer is used but this is less accurate than the Goldmann tonometer which is the gold standard in measurement.

Glaucoma - Gonioscopy2. Gonioscopy or examination of the eye drainage area

This test is done if you are suspected to have glaucoma. A special device called a gonioscope is used to examine the angle where the aqueous (eye fluid) drains in the eye. The viewing of this drainage area allows the eye

doctor to diagnose the kind of glaucoma a person may be suffering from in order for the correct treatment to be given to the patient.

3. Optic Nerve check

Glaucoma - Normal optic disc
Normal optic disc

An instrument called an ophthalmoscope or Fundus Imaging Camera is used to examine the optic nerve. The appearance indicates whether or not damage from glaucoma is present. It is important to examine the optic nerve from time to time, in order to look for progression of nerve damage due to glaucoma. The picture on the left shows a normal optic nerve (optic disc).

Glaucoma - Optic nerve damage
Optic nerve damage in glaucoma

Normal Optic Nerve

The picture on the right shows the damage that occurs to the optic nerve or optic disc due to glaucoma (indicated by the arrows).





Dr Gill will elaborate more on the eye tests that are done for glaucoma in the next issue of the Ipoh Echo.

For more information, contact Gill Eye Specialist Centre at 05-5455582, email: or visit