Glaucoma: Symptoms, treatment and prevention

 

Glaucoma is often called the “silent thief of sight,” because most of its types typically cause no pain and produce no symptoms until noticeable vision loss occurs.

For this reason, glaucoma often progresses undetected until the optic nerve already has been irreversibly damaged.

What is glaucoma?

Glaucoma is a group of related eye disorders that cause damage to the optic nerve that carries information from the eye to the brain.

In most cases, glaucoma is associated with higher-than-normal pressure inside the eye — a condition called ocular hypertension. But it can also occur when intraocular pressure (IOP) is normal. If untreated or uncontrolled, glaucoma first causes peripheral vision loss and eventually can lead to blindness.

Glaucoma is the second-leading cause of blindness worldwide (behind cataracts).

Types of glaucoma

The two major categories of glaucoma are open-angle glaucoma and closed angle glaucoma. The “angle” in both cases refers to the drainage angle inside the eye that controls the outflow of the watery fluid (aqueous) which is continually being produced inside the eye.

If the aqueous can access the drainage angle, the glaucoma is known as open angle glaucoma. If the drainage angle is blocked and the aqueous cannot reach it, the glaucoma is known as closed angle glaucoma.

Glaucoma symptoms

Most types of glaucoma typically cause no pain and produce no symptoms until noticeable vision loss occurs, but with acute angle-closure glaucoma, one experiences sudden symptoms like blurry vision, halos around lights, intense eye pain, nausea and vomiting.

If you have these symptoms, see an optician so steps can be taken to prevent permanent vision loss.

Diagnosis, screening and tests for glaucoma

During routine eye exams, a tonometer is used to measure your intraocular pressure, or IOP. Your eye typically is numbed with eye drops, and a small probe gently rests against your eye’s surface. Other tonometers send a puff of air onto your eye’s surface.

An abnormally high IOP reading indicates a problem with the amount of fluid (aqueous humour) in the eye. Either the eye is producing too much fluid, or it’s not draining properly.

Normally, IOP should be below 21 mmHg (millimeters of mercury) — a unit of measurement based on how much force is exerted within a certain defined area.

If your IOP is higher than 30 mmHg, your risk of vision loss from glaucoma is 40 times greater than someone with intraocular pressure of 15 mmHg or lower. This is why glaucoma treatments such as eye drops are designed to keep IOP low.

Other methods of monitoring glaucoma involve the use of sophisticated imaging technology to create baseline images and measurements of the eye’s optic nerve and internal structures.

Then, at specified intervals, additional images and measurements are taken to make sure no changes have occurred that might indicate progressive glaucoma damage.

Glaucoma treatments

Treatment for glaucoma can involve surgery, laser treatment or medication, depending on the severity. Eye drops with medication aimed at lowering IOP are usually tried first to control glaucoma.

Because glaucoma is often painless, people may become careless about strict use of eye drops that can control eye pressure and help to prevent permanent eye damage.

In fact, not complying to prescribed glaucoma medication program one of the major reasons for blindness caused by glaucoma.

If you find that the eye drops you are using for glaucoma are uncomfortable or inconvenient, never discontinue them without first consulting your optician about a possible alternative therapy.

Exercise may cut glaucoma risk

Can you reduce the glaucoma risk? According to a recent European study, exercise lessens the chance that some people will develop glaucoma because it helps improve blood flow in your body and your eyes.

In addition to regular exercise and an active lifestyle, you also can reduce your risk for glaucoma by not smoking, maintaining a healthy weight, and eating a varied and healthy diet.

Source:

allaboutvision.com/en-gb/conditions/glaucoma/

 


Aritificial intelligence used to develop an early warning system for AMD

Researchers at Moorfields Eye Hospital and UCL Institute of Ophthalmology have developed an artificial intelligence (AI) system that can help predict whether people with age-related macular degeneration (AMD) will develop the more serious form of the condition in their ‘good eye’. This is part of our wider, ongoing partnership with DeepMind and Google Health.

AMD involves damage to the macula, the central part of the retina at the back of the eye. AMD causes loss of central vision, affecting the ability to read, drive, watch television, recognise faces, and many other activities of daily living. It is very common that patients develop wet AMD in one eye and start receiving treatment, before later developing it in their other eye.

Macular degeneration mainly affects central vision, causing “blind spots” directly ahead (Macular Society).

 

The AI system developed by Moorfields, researchers from DeepMind, and Google Health, may allow closer monitoring of the “good eye” in patients at high risk, or even guide use of preventative treatments in the future.

Pearse Keane, consultant ophthalmologist at Moorfields Eye Hospital, said:

“Patients who have lost vision from wet AMD are often particularly worried that their “good eye” will become affected and, as a result, that they will become blind. We hope that this AI system can be used as an early warning system for this condition and thus help preserve sight.”

“We are already beginning to think about how this will let us plan clinical trials of preventative therapies – for example, by treating eyes at high risk earlier.”

“With this work, we haven’t solved AMD, but we believe we have found another big piece of the puzzle.”

Reena Chopra, research optometrist at Moorfields Eye Hospital, said:

“We found that the ophthalmologists and optometrists in our study had some intuition into which eyes will progress to wet AMD. The AI was able to outperform them, indicating there are signals within OCT scans that only the AI can detect. This unlocks new areas of research into a disease where there are still many unanswered questions about how it develops.”

Source:

Read the paper in Nature Medicine.

Read the Google Health blog and DeepMind technical blog.


National Eye Health Week

This week is National Eye Health Week.

We are raising awareness of the benefits of regular eye examinations.

Please copy and paste the link below to take part in the survey

http://www.visionmatters.org.uk/eye-health-questionnaire/eye-health-questionnaire

There are a million people in the UK currently living with ‘avoidable’ sight loss – leaving them unable to do things such as drive. Forecasters predict this figure could rise by a third by 2030, if action isn’t taken now[1].

Prevention and early diagnosis of common eye conditions are key to reducing the number of people suffering sight loss unnecessarily” explains David Cartwright Chairman of Eye Health UK “however, in towns and cities like Bristol, Liverpool, Luton and Manchester we are seeing a worrying number of people failing to take up their entitlement to free NHS sight tests and displaying high levels of smoking and obesity – two lifestyle factors linked to sight loss.”

Lifestyle habits impact your eye health regardless of your genetic predisposition.[2] Being physically active has been shown to reduce your risk of visual impairment by 58 per cent versus somebody with a sedentary lifestyle[3]; whilst a Body Mass Index (BMI) of 30+ has been linked to the four most common causes of sight loss: macular disease, glaucoma, cataract and diabetic retinopathy.[4]

Research published in the British Medical Journal reveals as many as one in five cases of Age-related Macular Degeneration (AMD), the UK’s leading cause of blindness, are caused by tobacco consumption.[5] Making smoking directly responsible for around 120,000 cases of AMD in Britain today.[6]

Poor uptake of regular eye tests is another big risk to the nation’s eye health. Almost 14 million (13.8) of us fail to have our eyes checked once every two years, as recommended, and one in 10 of us have never had our eyes checked.[7]

Go to visionmatters.org for more information.


After blindness, the adult brain can learn to see again

More than 40 million people worldwide are blind, and many of them reach this condition after many years of slow and progressive retinal degeneration. The development of sophisticated prostheses or new light-responsive elements, aiming to replace the disrupted retinal function and to feed restored visual signals to the brain, has provided new hope. However, very little is known about whether the brain of blind people retains residual capacity to process restored or artificial visual inputs. A new study published in the open-access journal PLOS Biology by Elisa Castaldi and Maria Concetta Morrone from the University of Pisa, Italy, and colleagues investigates the brain’s capability to process visual information after many years of total blindness, by studying patients affected by Retinitis Pigmentosa, a hereditary illness of the retina that gradually leads to complete blindness.

Fundus of the patient’s eye implanted with Argus II Retinal 98 Prosthesis, taken soon after the surgery Image Credit: Castaldi E, Cicchini GM, Cinelli L, Biagi L, Rizzo S, Morrone MC (2016)

 

The perceptual and brain responses of a group of patients were assessed before and after the implantation of a prosthetic implant that senses visual signals and transmits them to the brain by stimulating axons of retinal ganglion cells. Using functional magnetic resonance imaging, the researchers found that patients learned to recognize unusual visual stimuli, such as flashes of light, and that this ability correlated with increased brain activity. However, this change in brain activity, observed at both the thalamic and cortical level, took extensive training over a long period of time to become established: the more the patient practiced, the more their brain responded to visual stimuli, and the better they perceived the visual stimuli using the implant. In other words, the brain needs to learn to see again.

The results are important as they show that after the implantation of a prosthetic device the brain undergoes plastic changes to re-learn how to make use of the new artificial and probably aberrant visual signals. They demonstrate a residual plasticity of the sensory circuitry of the adult brain after many years of deprivation, which can be exploited in the development of new prosthetic implants.

Article: Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis, Castaldi E, Cicchini GM, Cinelli L, Biagi L, Rizzo S, Morrone MC, PLOS Biology, doi:10.1371/journal.pbio.1002569,