HOW IS GLAUCOMA DETECTED?

There are a variety of diagnostic tools to determine the presence or absence of glaucoma even when there are no symptoms. Here is a brief description of the tools and how they are used:

Tonometer

A tonometer measures eye pressure. In a procedure known as applanation tonometry, local anaesthesia is administered with eye drops. Then the patient sits at a slit-lamp where a plastic prism is gently pushed against the eye to measure IOP. Air tonometry is an investigation, in which a puff of air is directed onto the cornea to measure IOP. No anaesthesia is required here, as the instrument does not come into eye contact.

A visual field test  tells your eye doctor if and to what extent glaucoma has affected your range of vision. The visual field test is an important indicator of the extent of damage IOP has inflicted on the optic nerve. There are various field tests a patient may be subjected to. In a computerised visual field test, the patient’s chin is placed on a stand attached to a computerised screen. Whenever the patient sees a flash of light, she/he is asked to press a button and the doctor takes a printout of your field vision. The Goldmann perimeter test is similar, but no computer is used. The examiner notes down whenever the patient indicates that the light is visible

The examiner can look directly at the optic nerve through the pupil with an ophthalmoscope. The appearance and colour of the optic nerve shows whether damage is there and to what extent.

Gonioscopy is the process of examining the intraocular fluid outflow drainage angle. Eye constantly produces fluid and there is a drainage angle for it to flow out. This test can be used to determine whether the High eye pressure is caused due to closed/blocked angle (angle closure glaucoma) or the angle is open or not functioning well(open angle glaucoma). This is highly important as the management each sub-type is slightly different.  In this test, a mirrored lens is placed on the surface of the eye after instilling local anaesthesia containing eye drops.

Pachymetry is the test which is used to measure the thickness of the front window of the eye (cornea). The eye is numbed with the help of drops then contact probe is used quickly to measures the thickness and this is completed in few seconds.  A cornea which is very thin or very thick can affect the pressure /tonometry readings a thin cornea would increase the risk of developing glaucoma.

Diagnosis of glaucoma would involve medication and vision possible surgical intervention to preserve vision and quality of like.

Educating the patient involves:

  • To understand what the disease is.
  • The importance of the treatment.
  • The risk to first degree relatives.

  • Optical Coherence Tomography (OCT) is used to measures the retinal nerve fiber layer thickness in glaucoma which is used to the detect damage.
  • Heildelberg Retinal Tomography (HRT) is used to observe the changes in the structure of the optic nerve and used to detect early progression of glaucoma
  • Diagnosing Glaucoma with imaging (GDx) enables to take exact measurement of retinal fibers which would help in the diagnosis of glaucoma.