Dr Seah completed his fellowship training in USA in 1991. He served as the head of Glaucoma Service in Singapore National Eye Centre from 1991 to 2005 as well as Head of Glaucoma Research Unit in Singapore Eye Research Institute from 1992 to 2005. In addition, he was the Founding Executive Member of the Asian Oceanic Glaucoma Society (AOGS). Apart from the diagnosis, investigation and treatment of glaucoma, Dr Seah is especially well trained in handling complex glaucoma conditions.
WHAT IS GLAUCOMA?
Glaucoma is a disease that affects the optic nerve connecting the eye to the brain, usually due to build up of fluid pressure within the eye. Unless this pressure is brought down and controlled, this increase in pressure may cause progressive damage to the optic nerve and loss of nerve fibers, resulting in loss of vision. Glaucoma runs in families and the risk increases with age.
TYPES OF GLAUCOMA
Primary Open-Angle Glaucoma (POAG)
Primary Open-angle glaucoma (POAG) is the most common type of glaucoma. In POAG, although the entrances to the drainage sites are wide open, but it is being clogged by very tiny collections of material or does not function normally for unknown reasons. Thus, fluid in the eye is being trapped and this causes an increase in eye pressure. It is important to understand that open angle glaucoma can happen at any level of eye pressure.
Open-angle glaucoma develops slowly and is a lifelong condition. Early diagnosis can prevent further vision loss.
Angle-Closure Glaucoma (ACG)
Angle-closure glaucoma (ACG) is a less common form of glaucoma. Unlike open-angle glaucoma, the angle of the fluid drainage channel in patients with ACG is critically narrow or completely occluded, leading to a sudden increase in eye pressure.
It can be categorized into Acute Angle-Closure Glaucoma and Chronic Angle-Closure Glaucoma.
- Acute Angle-Closure Glaucoma: This form of glaucoma is characterized by a sudden elevation in eye pressure. Acute Angle-Closure Glaucoma requires immediate medical attention as it can cause blindness in a matter of hours.
Study co-conducted by Dr Seah found that several years after being seen with Acute Angle-Closure Glaucoma, 17.8% of subjects examined were blind in the attack eye, and almost half had glaucomatous optic nerve damage. Subjects with Acute Angle-Closure Glaucoma would benefit from regular follow-up to monitor for visual field decline and glaucoma development.
- Chronic Angle-Closure Glaucoma: This type of glaucoma is more common in patients with hyperopia (Long-sightedness). The thickening of the lens makes the angle even narrower. The drainage angle is obstructed in a slow, progressive fashion.
Normal Tension Glaucoma
In Normal Tension Glaucoma, there is glaucoma damage to the optic nerve even though it is not accompanied by high eye pressures like other forms of glaucoma. It is hypothesized that a reduced of blood supply to the optic nerve may cause the damage. Because eye pressure is not a good indicator in this case, the diagnosis can only be made by evaluating the condition of the optic nerve and by checking for peripheral vision loss.
Congential glaucoma is a rare condition that may be inherited. It is a result of abnormal or incomplete development of the eye’s drainage system during the prenatal period. This leads to increased intraocular pressure, which in turn damages the optic nerve.
Signs and symptioms of congential glaucoma include enlarged corneas, cloudy corneas, light sensitivity, poor vision and tearing.
Secondary Glaucoma is a result of other eye conditions or general body diseases, increasing the difficulty for the fluid to drain efficiently, leading to optic nerve damage and vision loss. It can occur due to advanced diabetes mellitus, advanced cataracts, taking of corticosteroid drugs, trauma or inflammation. Patients who undergo eye surgery for conditions other than glaucoma can also have elevated eye pressure that leads to the development of glaucoma.
The term glaucoma suspect refers to a patient who is at risk of developing glaucoma due to the presence of several risk factors, but have no proven glaucomatous optic nerve damage.
Early diagnosis and timely treatment is important to prevent glaucoma-related blindness. Periodic follow-up visits with the doctor are necessary to see if there are changes to the appearance of the optic nerve, the visual field, or to the eye pressure.
Some of the risk factors include:
Family history of glaucoma
High eye pressure
Long-term corticosteroid use
Medical conditions such as advanced Diabetes Mellitus
Ethnicity (East Asian heritage, African)
Gender (Women are 3 times more likely than men to develop Primary Angle-Closure Glaucoma)
Study co-conducted by Dr Seah found that there is a high incidence of Acute Angle-Closure Glaucoma in Singapore, with elderly women being the highest risk group. Chinese Singaporeans are at higher risk than other ethnic groups (Malay and Indian).