Primer on Age-Related Macular Degeneration

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Macular degeneration is when the part of the retina at the back of the eye called the macular undergoes changes. These changes can cause the appearance of sight problems, with central vision loss being the most common.

Age-related macular degeneration (AMD) occurs most often due to the passage of time. It most commonly develops in people over the age of 65, although there are cases where individuals in their forties or fifties will also experience a degradation of the macular. It can affect one eye, both eyes, or one then the other.

 

Macular Degeneration Risk Factors

However, age is only one of the factors that can influence the presence of AMD. Even though the exact cause of the condition has not been identified, there are a series of other elements that may increase the risk. These include:

  • Gender - Statistics show that more women develop AMD compared to men. It has been posited that this may be due to the fact that women tend to live longer than men and therefore have longer time in which to develop macular degeneration.
  • Genetics - It has been found that families with multiple cases of AMD can pass the condition down to later generations, although this does not always happen.
  • Lifestyle - A lack of exercise and high blood pressure can put the body at risk of macular degeneration, so living a healthy lifestyle is recommended to minimise danger. This includes ensuring that a healthy diet is maintained as deficiencies in certain vitamins and minerals are thought to contribute to the development of AMD.
  • Smoking - This activity will generally increase risk of age-related macular degeneration.
  • Sunlight - There have been studies that suggest prolonged exposure to ultraviolet light can increase the chance of developing macular degeneration. Although there is not conclusive evidence to back this up, the benefits of shielding eyes from UV light have been proven.

There are 2 main types of age-related macular degeneration: wet and dry.

Dry AMD occurs as the macula begins to thin due to retinal cell death and drusen, small nodes of protein, start to form. This develops slowly over time and the individual will gradually experience diminished central vision. Dry AMD will only ever affect central vision, leaving peripheral vision intact. This means that those with this condition will never suffer complete vision loss from dry AMD.

Wet AMD, on the other hand, is regarded as the more serious of the two. It occurs when blood vessels grow into the macula, begin to leak fluid or bleed, and cause scarring. Wet AMD can happen quickly and cause visual problems to suddenly appear. Like dry AMD, complete sight loss is not possible from just wet AMD.

It is important to note that “wet” and “dry” do not refer to the hydration levels of the eyes. Instead they are used to describe what an optometrist sees when examining the macula.

 

Symptoms of Macular Degeneration

Every individual’s condition will progress differently and which symptoms develop will vary from one to the other. Here are some of the most common symptoms for those with age-related macular degeneration.

  • Dark spots or gaps in the centre.
  • Fading colours.
  • Blurriness.
  • Light sensitivity.
  • Straight lines may appear distorted.
  • Harder to make out details.

 

Treatments and Cures for Macular Degeneration

The sad news is that there is currently no treatment method for dry AMD. There has been some studies that show increased intake of certain vitamins may be able to slow down the progression of dry AMD, however no way to completely prevent the condition has been found.

There is better news for those with wet AMD. Anti-vascular endothelial growth factor (anti-VEGF) drugs can be injected into the eye to inhibit the formation of new blood vessels. Normally, a course of three injections is given over the period of three months, after which it is advised to have regular check ups to verify whether more will be needed.

Although there is a high success rate for anti-VEGF treatment, there is a small possibility that the increased pressure in the eye resulting from the injection can cause retinal detachment. Infections can also occur but similarly the chance is very small.

However, it must be noted that anti-VEGF injections can only stop the growth of new blood vessels. They will not be able to reverse any damage done by blood vessels that have already caused damage to the macula.

Primer on Nystagmus

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Nystagmus (pronounced “ni-stag-muss”) is a condition where the eyes of an individual will undergo uncontrollable rapid movement.

The movement can be side to side, up and down, circular, or any combination of the three. It can also occur in both eyes independent of each and can vary in speed. Due to the complexity and recalcitrant behavior, the vision that the patient may experience can be affected. Most will find that they have a reduction in sight.

There are two main types of nystagmus: congenital (or infantile) and acquired.

Congenital nystagmus occurs in infants within the first few months of their birth. Rather than seeing things as “shaky”, most children will have their vision blurred. Causes may be due to problems in the development of the eyes of regions of the brain that affect the visual system. Some will also find that the condition is inherited from their parents or the byproduct of a different medical condition. There are also those with “idiopathic infantile nystagmus”, which is when the cause is unidentifiable.

Acquired, on the other hand, is found later in life and can be caused by anything that affects the function of the eye. This can range from eye diseases to seemingly unconnected illnesses to lifestyle choices. Adults with acquired nystagmus will often describe their vision as “shaky”.

The main symptom associated with nystagmus is uncontrollable eye movement. In addition, this can lead to various other problems:

  • Long or shortsightedness
  • Light sensitivity
  • Dizziness
  • Headaches
  • Poor depth perception
  • Poor balance

Unfortunately, there is currently no cure for nystagmus.

However, it is possible to reduce the effects associated. Glasses can be worn to help with reduced vision and larger text sizes can greatly aid children who are learning to read.

Some people may also find that they have a “null zone”. This is a point at which the involuntary eye movement is reduced and could involve maintaining the head at a tilted position.

Operations can help reduce the necessity for these awkward positions and studies have been done to test the possibility and efficacy of altering or enlarging a patient’s “null zone” through surgical intervention. There has also been research into the use of non-surgical intervention methods such as contact lenses and prisms.

Primer on Cataracts

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The lens in an eye function similarly to those in cameras. They help to focus the visual surrounding onto the retina to provide an undistorted picture.

What this means is that in order for the lens to function at its maximum capacity, one vital condition is that the lens remains transparent.

Cataracts is a condition where the cells and water content in the lens undergo changes. The individual’s lens may then begin to develop cloudy patches. Over time, these patches can increase in size and lead to vision becoming hazy, blurry, and lacking in colour. While the condition usually develops in both eyes, when and how will not necessarily be the same. Some may find that their vision drastically changes in a few months, while others may not experience any changes for years.

According to an assessment from the World Health Organization (WHO), cataracts are responsible for 51% of world blindness. Although most cases are related to the general side-effects of ageing, it can be caused by injuries, other eye conditions, or a variety of lifestyle choices. It is also possible for children to be born with cataracts (often referred to as “congenital”, “infantile”, or “developmental” depending on how early they manifest).

Fortunately, once cataracts have been confirmed, they can be removed at any stage. The surgery involves replacing the affected lens with an artificial lens implant. This is normally done under local anaesthetic and can be performed as a day procedure. It is not uncommon for a patient’s ophthalmologist to delay surgery if the cataracts have not progressed very far. This is done due to the slight risk associated with the procedure as well as the personal situation of the patient. Under the NHS, operations are normally only suggested if the patient’s vision is outside the legal limit to drive.

For example, if the patient has another existing eye condition, it is possible that cataract surgery may not be able to improve the individual’s sight.

Additionally, cataracts surgery can only be performed in one eye at a time. This means that there may be a period of months between operations if both eyes need treatment.

Post-surgery recovery is normal fairly straightforward. The dressing can normally be removed after a day and antibiotic drops are given to help stave off infection. Other short-term precautions including not rubbing the eyes, staying away from heavy activities, and not swimming.

Primer on Charles Bonnet Syndrome

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Charles Bonnet (pronounced “bon-nay”) was a naturalist and philosopher born in Geneva in 1720. At around 40 years-old, he released a book called “Essai Analytique sur les Faculties de L’Ame” (Analytical Essays Concerning the Faculties of the Mind) in which he described how his 87 year-old grandfather, Charles Lullin, experienced visual hallucinations that occurred at spontaneous times.

Fast forward to 1967, the term “Charles Bonnet Syndrome (CBS)” was introduced to the world by another Geneva native, George de Morsier.

CBS can be described as the presence of visual hallucinations among those with sight loss. These hallucinations are completely the product of visual impairments and are not signs of mental health deterioration.

There are generally two main types of hallucinations experienced:

  • Simple patterns and shapes, like brickwork or mosaic
  • Complex images of people, landscapes, or objects

These will only affect a person’s sight. Smell, hearing, and touch will not be compromised.

The reasons behind these hallucinations are not yet entirely clear. It is suggested that when sight loss occurs, the brain no longer receives as many signals from the eyes. It then attempts to make up for this lack of communication by creating its own. These end up translating into “phantom” images seen by the individual.

CBS normally appears in the weeks and months following a big change in sight loss. Fortunately, for the majority of people, these hallucinations get less frequent with time, although reappearance of hallucinations five years after initially starting is a possibility.

One of the most serious aspects of CBS is its unknown nature. Many people who begin experiencing hallucinations are often unaware of its true nature. This can cause fear for both the individual as well as their family and friends, due to visions being taken to be symptoms of mental health issues.

Unfortunately, there is no direct way to diagnose the presence of CBS. Doctors will generally talk to the patient about their medical history and may carry out tests to rule out other causes for the visual hallucinations.

Although no treatment is available, given enough time, CBS can improve over time. It has been found that often simply a better understanding of CBS can help patients cope better as they understand that it is purely a normal result of sight loss rather than anything to do with mental health. In some cases, medication for epilepsy, Parkinson’s Disease, and dementia have been able to help, but due to the possibility of severe side-effects, it is only recommended for those who are seriously affected and under supervision.

There are, however, a few self-help methods that may relieve any hallucinations experienced:

  • Changing lighting conditions, i.e. making it brighter or dimmer
  • Scanning from left to right repeatedly without moving the head for 15 secs. This can be done 4 or 5 times if hallucination continues.
  • Staring at an image and blinking rapidly, or attempting to touch it.
  • Performing a task that includes large movement, e.g. going to the kitchen to make coffee
  • Sleeping and resting well. Fatigue and stress may increase the likelihood of hallucinations.

Primer on Retinopathy of Prematurity

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The World Health Organisation (WHO) estimates that over 15 million babies are born prematurely (generally agreed to be at less than 37 weeks) every year. This equates to 1.5 times the population of Belgium.

Premature babies are at an increased risk of complications due to the non-optimal gestation period afforded them. If blood vessels in the retina fail to develop fully, babies can be born with retinopathy of prematurity (ROP).

The retina is responsible for taking light that enters the eye and converting it into signals for the brain to interpret. They are supplied with blood through an extensive network of blood vessels that start to develop 16 weeks into pregnancy. Normally, it takes the full term (40 weeks) for the blood vessels to fully develop.

If this process is interrupted, it can leave the retina short of the blood vessels it requires to function properly. In order to make up for this deficiency, it may stimulate new blood vessels to grow. However, these are often weak and can lead to scarring and damaging of the retina. Severe ROP can also lead to retinal detachment.

In the UK, babies born under 32 weeks or at a weight of under 3lbs will be screened for potential ROP. Eye examinations will continue until the risk of needing treatment has passed.

 

Retinopathy of prematurity can be described in 5 stages:

  • In stage 1, the new blood vessels have not started to grow and the mark between where blood vessels are present and not is flat. Usually recovery without treatment is possible at this stage.
  • At stage 2, the mark between the two regions has become raised, but still no new blood vessels have begun to grow. It is still possible to recover without treatment at this stage but regular checkups to monitor the condition are recommended.
  • Stage 3 is normally characterised by the growth of new vessels. These vessels are weak and can lead to scarring which may cause sight problems. Treatment is normally required at this stage.
  • The new vessels that grew have begun to shrink and cause scarring in stage 4. This may start to pull the retina away from the back of the eye.
  • During stage 5 the retina has fully detached and this would lead to permanent sight loss.

 

Treatment for retinopathy of prematurity most often involves the removal of the fragile new blood vessels that grow. This can be done with laser treatment, eye injections or cryotherapy.

If retinal detachment has begun, the patient may require surgery to help hold the retina to the back of the eye. Unfortunately, this needs to be done early during stage 4. If the condition has progressed to stage 5, it is unlikely that useful vision can be salvaged.

Primer on Nutritional Optic Neuropathy

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A young boy, aged 17, made the news when he developed a form of blindness after years of malnourished dieting.

After examination, it was found that the teenager’s diet had given him nutritional optic neuropathy, a type of acquired optic neuropathy.

Optic neuropathy is when the optic nerve is damaged which can then lead to changes in the individual’s sight. This is due to damage done to the retinal ganglion cells and their axons which can cause modifications to the optic nerve head as well as the surrounding retinal nerve fibre layer.

Optic neuropathy can be caused by a variety of factors, including trauma, drugs, and genetics. Nutritional optic neuropathy occurs when the body is deficient in certain nutrients due to the individual’s diet.

Although those who develop this type of optic neuropathy solely due to nutritional malpractice are rare (they are more commonly found in regions where famine is prevalent), lacking certain nutrients is often a big factor in the progression of other forms of this condition.

Some of the main deficiencies responsible for nutritional optic neuropathy include:

  • Vitamin B-12 (cyanocobalamin)
  • Vitamin B-1 (thiamine)
  • Vitamins B-2 (riboflavin)
  • Folate

In the case of the teenager mentioned above, his diet consisted of chips, crisps, white bread, and sausages, which left his body in need of more vitamin B-12, among other nutrients.

In the early stages of nutritional optic neuropathy, visual acuity is normally the first to worsen. At this stage, if treated correctly, it is possible to reverse the detriment done and recover lost sight. If left untreated, patients can lose central vision as well as the ability to distinguish colours.

Damage can be permanent so it is important to seek clinical advice as soon as any change in sight is noticed so that treatment can start. An improvement in diet as well as vitamin supplements can help with staving off the later stages of the condition.

It must be noted that due to the rarity of primarily nutritional optic neuropathy in developed countries, the selectiveness of the diet could be a symptom of avoidant restrictive food intake disorder (ARFID), an eating disorder that is not due to body image issues.

Primer on Diabetic Retinopathy

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If you pool everyone with diabetes together and form a nation, they would be the third most populous country in the world.

Those with diabetes will normally find that they have increased levels of glucose in their blood. This can lead to nerve and blood vessel damage as well as an increased risk of cancer due to DNA harm.

Although, not everyone with diabetes will experience sight loss, diabetics will have a higher risk of developing certain visual impairments, such as cataracts and glaucoma.

One of the more common ones is diabetic retinopathy.

This is when the increase in blood sugar levels affect blood vessels at the back of the eye. This interferes with how the retina work and can lead to retinal vessels leaking or bleeding.

 

There are 4 main stages of diabetic retinopathy:

1. Background Retinopathy

This is when capillaries in the retina weaken and develop small areas of swelling. This can lead to small amounts of bleeding as well as the leaking of a fluid called exudate. Although this will normally not affect vision, if it is left untreated the condition can become worse and cause the condition to the next stage.

 

2. Non-Proliferative Retinopathy

Here we see more drastic damage to the capillaries in the retina and usually occurs after years of high blood sugar levels. Bleeding and leaking is more prominent and blood vessels are weakened, potentially losing the ability to transport blood which can cause the retina to malform. Eventually, blood vessels may be completely blocked, which will prompt the body to release growth factors to encourage the formation of new vessels.

 

3. Proliferative Retinopathy

By now, new blood vessels have been formed to help supply blood. However, they are weak and are prone to haemorrhaging and leaking. They can also grow on the retinal surface or inside the vitreous gel. When blood or fluid is leaked, this can damage the retina or block vision when inside the vitreous gel. Scarring can also occur and an increase in scar tissue can cause the retina to detach which may lead to serious sight loss.

 

4. Diabetic Maculopathy

The more common cause of serious sight loss, diabetic maculopathy can occur with or without proliferative retinopathy [Pipe, D.M. & Rapley, L.J. (2008). “Abnormal Ocular Conditions: A Handbook for Dispensing Opticians”]. It occurs when haemorrhaging or leaking involves the macular area of the eye and can cause central vision loss.

 

Symptoms of diabetic retinopathy may not occur at the beginning and can start to appear as the condition advances. Typical manifestations include:

  • Blurred vision
  • Dark spots or patches
  • Eye pain or redness
  • Reduction in night vision
  • Sudden sight loss

Treatment for diabetic retinopathy can depend on how far it has progressed. Laser surgery can be done on a localised area to help reduce swelling and seal up blood vessels. For larger affected areas, pan-retinal laser surgery can be used to shrink abnormal blood vessels and inhibit the release of growth factors. Vitrectomies are used to treat severe bleeding into the vitreous gel. Vitreous is removed and replaced with a clear salt solution to maintain the pressure in the eye.

However, these treatment methods are more aimed at preserving sight rather than restoring. As with many diseases, prevention is just as (if not more) important as treatment. Maintaining a manageable blood sugar level is key and this includes exercise, diet, and generally living a healthy lifestyle.

Primer on Stroke-related Vision Loss

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You push open the heavy oak doors of the pub and are instantly hit with a barrage of jovial sounds mixed with the scent of a strong alcohol and sweat cocktail.

Scanning round the establishment, you quickly locate your friends and make your way to the empty seat left, you presume, for you.

And then the drinks start.

After a few rounds or more, you start to notice a numbing sensation on the left side of your body. Your friends comment on how your left eye and mouth are drooping. You try to say that something seems wrong, but it all sounds garbled and nonsensical.

At first, you blame it on the alcohol, but then you realise that you can no longer move your left arm. You start panicking.

You’re having a stroke.

The next thing you remember is waking up in a hospital room. It’s dark and you’re alone.

You mentally check over yourself. Arm works. Face seems to be as expressive as ever. Mental calculations are tough, but you were never good at them anyway. Words sound clear enough.

Footsteps gradually increase in volume and you realise that they are coming to you.

You quickly close your eyes as light suddenly invade your eyes. As you become accustomed, you tentatively open your eyes.

But you can only see half of what you would normally see.

One side of your vision is gone.

 

Strokes occur when a part of the brain is deprived of oxygen. It is life threatening and can leave the victim/survivor with a series of conditions, ranging from mental to physical to cognitive.

There are also various visual problems that can arise. Here are some of the most common stroke related sight loss conditions.

 

Visual field loss

This is when parts of vision is lost. Hemianopia is when one half of vision is gone so those with the condition will only be able to see either the left or right half of what they are looking at.

It is also possible to lose central vision, which may mean that it is not possible to directly look at something.

 

Eye movement complications

Strokes can affect a victim’s control over their eyes. This may mean that the eyes are unable to coordinate with each other, which can cause diplopia (double vision).

Some may also experience an uncontrollable wobble of the eyes (nystagmus) which can result in reading difficulties.

 

Trouble with visual processing

Strokes can disrupt the way information is passed from the eyes to the brain and how that is processed. This miscommunication can often result in visual neglect, which is when something that is seen is not processed and therefore does not register with the individual. You may find that these individuals will unintentionally ignore people or objects because their brain has not interpreted the data sent by the eyes.

The other extreme is also possible as many will experience hallucinations caused by processing errors by the brain, giving them images of things that aren’t actually there.

 

Due to the wide range of visual conditions suffered by stroke victims, there is no one-fix-for-all. Treatment can help the victim cope and adapt to their vision loss, and can come in the form of rehabilitation, accessories, or smart glasses, depending on the exact nature of their condition.

Some people will find that their vision improves for up to 6 months after their stroke. But again this depends on how well their brain heals after the initial damage.

Primer on Glaucoma

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Glaucoma can trace its roots to Ancient Greece and is derived from the word Glaux which means owl. Ancient Greeks had a propensity to name diseases after animal due to their belief that this animal would then help the patient combat the disease.

And so it is the owl that plays a central role in combating Glaucoma.

Ancient Greek gem showing an owl taking centre stage in the fight against eye disease. [lww.com]

Glaucoma is an eye condition where the optic nerve is damaged. This is normally caused through buildup of fluid in the eye which increases pressure. The pressure can injure or exploit a pre-existing weakness in the optic nerve.

The effects of this damage may not be noticeable at first due to it normally developing over many years and primarily affecting peripheral vision. Because of this it is advised to take regular eye tests as this is usually how glaucoma is detected.

Due to the variable nature of the cause, there are five main types of glaucoma, with most characterised by patchy blind spots in peripheral or central vision of both eyes.

  • Primary open angle glaucoma is the most common type and is characterised by slow damage to the optic and changes to eyesight.
  • Closed angle glaucoma occurs when eye pressure rises suddenly and can be very painful.
  • Normal tension glaucoma is when the pressure is within the normal range but damage to the optic nerve still happens.
  • Secondary glaucoma is a result of the presence of another eye condition, an injury to the eye, or certain medication or treatments.
  • It is also possible to be born with an improper drainage system in the eye causing congenital glaucoma.

Currently, there is no cure to restore the vision of someone with glaucoma. However, it is possible to stop or slow the degradation of vision and stave away permanent sight loss by controlling the level of pressure in the eyes.

Eyedrops are the most common form of treatment with many people using them daily for many years. For some, it may be necessary to have laser eye treatment or surgery to help control the pressure.

Recent developments have seen specialty glasses produced which can condense a wider field of view and display it in a patient’s more narrow field of view, effectively replacing part of their lost vision. More and more people are finding these smart glasses useful in their daily lives and the future points towards more advanced developments and further innovation in this field.

Primer on Retinitis Pigmentosa

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“It’s like walking around while looking through a narrow tube. Then at night, imagine wearing thick, heavily darkened sunglasses. The irony is that, during the day, I actually need to wear sunglasses due to my intense light sensitivity.”

James C Laird, Retinitis Pigmentosa

Imagine what it would be like to not be able to fully see a scene from your favourite TV show, to only be able to see the nose of your loved ones, to have to read your favourite book letter by letter, to live your life one jigsaw piece at a time.

This is what it can be like for those with retinitis pigmentosa (RP).

RP is a group of disorders that involve the breakdown of photoreceptor cells in the retina, a part of the eye that translates light into usable information for the brain.

This can mean that those with RP will experience night blindness (one of the first symptoms) as well as a gradual decrease in their field of view. However, because retinitis pigmentosa is caused by a change in any one of over 50 genes, each case is different. Some may have perfect central vision, but are limited to 3 degrees field of view. Others may have small patches of clarity dotted around their vision. There are even those who experience kaleidoscopic sights.

RP is an inherited disorder and can be passed on to a child by parents who do not show signs of the condition. Conversely, parents with retinitis pigmentosa will not necessarily pass on the disorder to their children.

While currently there is no cure for RP, there has been much work done to make life easier for those with the condition. Smart glasses, like OXSIGHT Crystal, are able to potentially increase the field of view for those with usable central vision allowing users to do things they were not able to previously. There has also been much research into genetics to find a way to reverse the degradation, bringing hope for a cure in the future.

For more information on RP, see RNIB’s full guide.