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World Sight Day: focussing on the causes of sight loss

Posted: 14/10/2021

This article is one of a series of articles in support of World Sight Day and focusses on optic neuropathy, one of the most serious injuries experienced by patients that results in sight loss.

The optic nerve transports signals from the eye to the brain, which then changes the signals into images. Optic neuropathy occurs when there is damage to the optic nerve resulting in partial or complete vision loss. Vision is not possible without a healthy optic nerve so if the nerve is damaged, for example, by compression, or if its blood supply is disrupted, o then sight loss can quickly follow.  

The optic nerve is part of the central nervous system and cannot regenerate or repair itself. Once the optic nerve has been damaged, the sight lost as a result is not recoverable and the injury is permanent. While medication or surgery can help stem further damage it can only preserve the remining sight. No treatment can restore vision already lost as a result of damage to optic nerve.


One of the primary causes of optic neuropathy is untreated or poorly managed glaucoma. Glaucoma is a condition that occurs when the tubes that drain the fluid from the eye become slightly blocked or narrow resulting in a build-up of pressure within the eye. Such a build-up of pressure can damage the optic nerve that transmits images through the eyes to the brain. If this pressure is not treated, glaucoma can cause permanent visual problems and, in severe cases, permanent blindness.

Symptoms of glaucoma can include loss of vision, eye pain, seeing halos around lights, red eyes, nausea, and vomiting. The symptoms, particularly in the early stages of glaucoma, can be subtle but glaucoma is a leading cause of blindness worldwide. Patients who experience these symptoms should be suspicious and should attend an ophthalmologist for an eye check as early as possible.

Once a patient is diagnosed, they should be advised to attend regular eye health care checks to assess any progression of the condition and provide appropriate treatment. These may be monthly, initially, and may thereafter reduce to quarterly checks.

If a patient’s condition is not appropriately monitored on a regular basis, periods of time could elapse during which the pressure in the eye could increase without appropriate management and treatment. In such circumstances, if the pressure in the eye becomes too high, then injury to the optic nerve can occur via compression, causing permanent loss of sight.

Blood vessel disorder

Optic neuropathy may also be caused by a blood vessel disorder known as Giant Cell Arteritis (GCA). This is an inflammatory condition of large or medium-sized blood vessels (arteries). Damage to the wall of the vessels from the inflammation results in thrombosis (blood clots) which occlude the blood vessels and prevent blood and oxygen from being supplied to the brain.

Sometimes, the optic nerve is deprived of the blood supply it needs to continue functioning healthily and this can result in the patient experiencing symptoms of jaw pain, neck pain, headache, scalp tenderness, a general feeling of being unwell, weight loss and fever.  The sight specific symptoms generally experienced by GCA patients include transient visual loss and double vision.

GCA is a medical emergency. It is essential that, if a patient experiences some of the above symptoms, they seek advice from either their GP or a doctor in the eye emergency unit. If a diagnosis of GCA is suspected, treatment is required immediately in the form of corticosteroid therapy. Again, any sight loss that has occurred by that point is not recoverable but treatment will aim to prevent further loss of sight.

Surgical errors

Optic neuropathy can also occur following either specific surgical ophthalmic treatment or general treatment during which the patient is placed under general anaesthetic.

Our clinical negligence team has previously settled a claim for a patient who underwent spinal surgery to decompress his spinal cord. During the six-hour procedure, he was lying in a face down position. The decompression surgery was successful but, when the patient woke from the anaesthetic, he had suffered significant sight loss. Over the course of the following weeks he recovered some vision but suffered a permanent loss of useful sight in his right eye.

The expert anaesthetist instructed in that case was of the opinion that the anaesthetist involved in the patient’s care negligently allowed the patient’s blood pressure to fall below 75% of its usual level for almost five hours of the operation and below 60% for well over two hours. This, it was alleged, caused a reduction in blood supply to the patient’s optic nerve causing the permanent sight loss. Further detail about this successful claim can be found here.

Another case that demonstrates the risk of sight loss following surgery is a claim in which a patient suffered a significant increase in the pressure in her eye following routine cataract surgery.

As part of the procedure, the surgeon had inserted a viscous substance known as viscoelastic. This is routinely used to assist a surgeon to place the new artificial lens safely without damaging the patient’s eye. It is imperative, however, that the viscoelastic is washed-out at the end of the procedure because its retention can inhibit the eye’s ability to drain liquid and can, therefore, result in significant spikes in intra-ocular pressure.

As mentioned above, when discussing the importance of appropriate management and treatment of glaucoma, high pressure within the eye can compress and damage the optic nerve, which can result in considerable and permanent sight loss.

Arran Macleod, senior associate in the clinical negligence team at Penningtons Manches Cooper, comments: “Optic neuropathy is a serious injury that can cause a patient to suffer significant and permanent loss of sight. There are numerous causes, such as glaucoma, that  patients should know about through proper advice from their treating clinicians but, in other cases, it can be caused as a complication of another non-eye condition or following surgery.

“Given the seriousness of this injury, it is essential that glaucoma patients at risk of optic neuropathy are monitored regularly so that any changes in their condition are managed and treated quickly and appropriately. In other cases where GCA is suspected or where there are signs and symptoms of optic neuropathy following a surgical procedure, it is essential that a specialist vitreo-retinal surgeon is involved as quickly as possible to advise on the appropriate management to treat the condition and prevent any further sight loss.”

If you have suffered sight loss as a result of optic neuropathy and you have concerns that there may have been failures in your treatment or management, please do get in touch as we would be happy to provide you with some preliminary advice on the options available to you.

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