Glaucoma: How the silent eye disease can steal your sight without warning

Glaucoma can rob people of their sight without pain or obvious warning signs, leaving many unaware that their vision is deteriorating until permanent damage has occurred, Lions SightFirst Eye Hospital General Manager Dr Rizwana Peerbhoy, OGW, has cautioned.

The disease damages the optic nerve, which carries visual signals from the eye to the brain, and can cause irreversible vision loss if it is not detected and managed early. Peerbhoy is urging people to take regular eye examinations seriously, noting that clear vision and the absence of discomfort do not necessarily mean the eyes are healthy.

Speaking on Radio Generation on Thursday, Peerbhoy explained that glaucoma is often linked to a rise in pressure inside the eye when the channels responsible for draining fluid fail to work properly.

“Glaucoma is known as the ‘silent thief of sight’ because it often develops without early warning signs or pain. As the condition progresses, pressure begins to build up inside the eyes,” Peerbhoy said.

The eye naturally produces a clear fluid that nourishes its internal structures and helps maintain pressure. Under normal conditions, the fluid drains through a network of channels. When the drainage system becomes blocked or does not work effectively, fluid can build up, raising pressure and putting the optic nerve at risk.

The optic nerve plays a central role in sight by carrying signals from the retina, the light-sensitive layer at the back of the eye, to the brain, where they are processed into images.

When glaucoma damages the nerve fibres, the transmission of these signals becomes weaker, affecting a person's ability to see. Once the nerve has been damaged, the resulting loss of vision cannot be reversed.

“Glaucoma and retina conditions damage the optic nerve, and that at this time is irreversible. So if it starts to damage the optic nerve, it means the signal to your brain, of course, reduces, and then now that vision impairment at this stage is not reversible,” Peerbhoy said.

One of the difficulties in identifying glaucoma early is that it often begins by affecting peripheral vision, which allows people to see objects outside their direct line of sight. Central vision may remain clear in the early stages, making it possible for someone to continue reading, recognising faces and performing daily activities without realising that their eyesight is deteriorating.

Peerbhoy said this gradual loss of side vision can make the condition difficult to detect without a proper eye examination.

“A lot of times it starts in the periphery, so you know you may not notice it. Your central vision is good. Your peripheral vision starts to get diminished,” she said.

As the disease advances, the affected person's field of vision may become increasingly narrow. Without treatment, the damage can progress to severe visual impairment or blindness.

The gradual nature of the disease means that people may not seek medical attention until considerable damage has already occurred. The absence of pain, blurred central vision or other obvious symptoms should therefore not be taken as proof that a person's eyesight is unaffected.

Although sight lost to glaucoma cannot be recovered, treatment can help control the condition and limit further damage to the optic nerve. Available options include medication and specialised surgical procedures aimed at improving fluid drainage and reducing pressure inside the eye.

Peerbhoy said Lions SightFirst Eye Hospital was strengthening its capacity to manage the condition, with surgeons receiving training in different surgical techniques, including procedures that involve the use of valves to help drain fluid from the eye.

“It's treatable. It's manageable. There are medications, and now, in fact, at our center, our surgeons have gone to train for different types of surgical procedures, and even introduced valves,” she maintained.

She explained that the valves are used to support the drainage of fluid, helping control pressure and protect the remaining function of the optic nerve.

“Even your eye will get a valve, so the valve will come down, helping make sure that the fluids are drained and it keeps the vessels open so that it prevents further damage.”

The procedures involve specialised microsurgical instruments designed for delicate operations on the eye. Their purpose is to improve fluid drainage, manage pressure and reduce the risk of additional damage.

Peerbhoy's warning highlights the need for routine eye examinations, particularly because glaucoma can develop and progress without noticeable symptoms. Eye assessments can help identify abnormalities and determine whether further tests or treatment are necessary.

For people diagnosed with the condition, medication, regular monitoring and surgery where required can help manage its progression and preserve the vision they still have.

With optic nerve damage remaining irreversible, early detection and timely treatment are key to limiting the effects of glaucoma and reducing the risk of preventable blindness.