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POORLY PROCESSED GARRI MAY CAUSE IRREVERSIBLE BLINDNESS – EXPERTS WARN
Medical experts have warned that consuming poorly processed garri and unregulated alcoholic beverages could lead to irreversible blindness due to their toxic effects on the optic nerve.
They explained that the presence of high cyanide content in inadequately fermented garri and methanol in locally distilled spirits can cause permanent nerve damage that impairs vision.
A Nigerian social media health influencer and medical doctor, Chinonso Egemba, said the presence of harmful substances in cassava, the raw material for garri, could potentially lead to blindness if the finished product is not properly processed for consumption.
In a video, Egemba, known popularly as Aproko Doctor, explained that Garri, which is derived from cassava, contains compounds known as cyanogenic glycosides, specifically linamarin and lotaustralin.
According to him, during the processing of cassava, these compounds can be converted into hydrogen cyanide, a substance that can be harmful to the body if consumed in large quantities.
“This hydrogen cyanide can start to affect certain tissues in your body. And one of the things it can affect is your eye – the optic nerve and the retina,” he said.
Bur a professor of ophthalmology, Adeola Onakoya, said poorly processed garri retains unsafe levels of cyanide, a compound toxic to the nervous system.
When consumed regularly, the don explained that it can damage the optic nerve gradually without obvious symptoms like pain or redness, making vision loss difficult to detect until it becomes permanent.
Onakoya, who is the Head Glaucoma Services, Lagos University Teaching Hospital, Idi Araba/College of Medicine, University of Lagos, stressed that once the optic nerve is damaged, the loss of sight cannot be reversed.
Aside from causing irreversible vision loss, the don explained that high cyanide content in the body can also affect an individual’s general wellbeing.
“The reason is thats poorly processed garri has a very high cyanide content, and it’s not just injurious to the eyes—it can affect the general health of the individual. Cyanide is toxic to the system, and the specific effect it has on the eyes is that it damages the optic nerve. This is called optic neuropathy. The cyanide causes damage to that nerve to the extent that the damage is irreversible.
“And the thing about the nerve is, once it’s damaged, it’s irreversible; there’s nothing you can do to recover vision. Quite a number of people indulge in this. There are even some people who eat cassava directly, and they are also at risk. You know, people just go to the farm, harvest or pick the cassava, and cook it. So, if the cyanide content is very high, it tends to cause a lot of problems with the nerves in their eyes,” the seasoned ophthalmologist said.
She explained that the condition often does not present notable signs or symptoms.
“They may not see any notable signs or symptoms in the eye, no redness, no pain. They just notice that their vision is gradually going, and it happens over a period of time, which unfortunately may not be reversible. That’s why we say poorly processed garri causes blindness, and not all garri.
“Garri is fibre and carbohydrates; it’s good. But you don’t want to eat it in excess, because even if it doesn’t have cyanide, its carbohydrate content, which breaks down into sugar, can be a problem. You don’t want to overload your system with sugar and end up with diabetes. So these are the issues,” the ophthalmology don added.
Onakoya also raised concerns over the increasing consumption of roadside spirits containing high concentrations of methanol.
These alcoholic drinks, she said, can destroy the optic nerve within hours of ingestion.
“As I was talking about the cyanide content in poorly processed garri, the other thing that comes to mind is alcohol, particularly the spirit. It causes the same damage that high cyanide content causes. But this one is more aggressive and almost instant.
“For instance, if you drink alcohol with 70 to 80 per cent concentration, very high in methanol, it can damage the optic nerve instantly. And it’s irreversible; there’s nothing you can do. It just damages the nerves. So when someone drinks these spirits, which contain high methanol content, it’s not friendly to the optic nerves at all, just as it’s not friendly to the liver,” the don said.
Also, a Chief Consultant Ophthalmologist, Dr. Festus Oshoba, urged Nigerians to adopt regular eye screening, adding that screening is key to early diagnosis and treatment of preventable and curable conditions.
He urged individuals experiencing eye discomfort or infections to seek prompt medical attention from certified eye care providers.
“Use a calendar or chart at home to self-check your vision daily. The moment you can’t read what you used to see clearly, visit your doctor,” the ophthalmologist said at the 26th Annual Faculty of Ophthalmology Lecture of the National Postgraduate Medical College of Nigeria.
Oshoba referenced cultural misconceptions and spiritual interpretations of blindness and eye diseases, such as attributing loss of vision to curses.
“Many of these cases are due to conditions like glaucoma, diabetes, or brain tumours, not spiritual attacks,” he explained.
