Glaucoma, retinitis pigmentosa and diabetic retinopathy. Concept, characteristics and differences

Text by Reddit user Blind Insider

Today, the various diseases that cause blindness are on the rise. However, we will focus on the top three diseases so that you can preventively resort to a specialist if you have any warning symptoms and if unfortunately, you already suffer from it, you can also control it to avoid any future complications.

Let's start with glaucoma.

What is glaucoma?

Glaucoma is a disease that damages the optic nerve of the eye. It usually occurs when fluid builds up in the front portion of the eye. Excess fluid increases the pressure in the eye thus damaging the optic nerve.

Glaucoma gets its name from the greenish color that the pupil acquires.

So far it has not been possible to specify what causes glaucoma, however, most patients show elevated eye pressure, although there are some types of glaucoma where the pressure remains normal.

Some cases of hereditary glaucoma have also been detected, where the genetics provided for elevated eye pressure and damage to the optic nerve.

Although glaucoma can appear at any age, it is much more common in people over the age of 60.

As the optic nerve deteriorates, blind spots appear since the optic nerve is made up of more than 1 million nerve fibers, much like small electrical wires, and when  these stop working, eyesight tends to deteriorate and if they all stop functioning, blindness ensues.

Unfortunately, glaucoma cannot always be detected as most of the time it does not cause any symptoms until it is already at an advanced stage.

The Mayo Clinic reports that elevated eye pressure is due to a buildup of fluid (aqueous humor) circulating inside the eye. Usually, this internal fluid drains through a tissue called the trabecular mesh at the angle at which the iris and cornea meet. When excess fluid is produced or when the drainage system does not work properly, the fluid cannot drain at a normal rate and eye pressure increases.

Main types of glaucoma

The most common are:

Chronic open-angle glaucoma:  This is the most common type of glaucoma, fortunately it is not painful but unfortunately at first it does not cause any type of symptom, so it is more difficult to detect it and it happens so slowly that you can lose your sight before you know it.

Here, the eye cannot drain the fluid normally; because, although the drainage angle that forms between the cornea and the iris is open, the trabecular mesh is partially blocked and the pressure increases and the optic nerve starts getting damaged.

Closed-angle or narrow-angle glaucoma: This type of glaucoma occurs when the iris is too close to the angle of ocular drainage, thus causing it to be blocked.

If the drainage angle is completely blocked, it is called an acute attack.

These types of attacks have symptoms, which are very delicate and must be treated urgently to avoid blindness.

Symptoms include:

  • Nausea
  • Vomiting
  • Severe headache
  • Severe eye pain
  • Sudden blurred vision
  • Seeing colored rings around the lights
  • Redness of the eyes

People who are at higher risk for glaucoma are those who:

  • Are over 40 years old
  • Have a vision problem such as nearsightedness or farsightedness
  • Have Asian, African, or Hispanic ancestry
  • Have relatives with the disease
  • Suffer some injury to the eye
  • Have elevated eye pressure
  • Suffer from diabetes, migraines, poor blood circulation or high blood pressure
  • Suffer from thinning of the corneas
  • Narrowing of the optic nerve
  • Have used steroids for a long time

If you have two or more of the above characteristics, the risk may be higher.

How can glaucoma be prevented?

As glaucoma is considered a silent disease while it is in the early stages, the only way to prevent it is getting eye examinations at least once a year.

It is recommended to carry out a complete study where your specialist:

  1. Checks the optic nerve to make sure there is no damage
  2. Measures eye pressure to make sure it's normal
  3. Checks the drainage angle to make sure it is not blocked
  4. Measures the thickness of the corneas
  5. Does a peripheral vision test.

What is retinitis pigmentosa?

This eye disease known as RP causes severe damage to the retina, since the retina is a layer-like tissue that is located at the back of the eye through which light images are converted into nerve signals that are sent to our brain.

The cells that control night vision, also known as rods, and retinal cone cells are usually the most damaged by this disease.

The main characteristic of this disease is dark deposits on the retina. This is a rare disease and is mostly hereditary due to genetic defects. It is considered a degenerative disease of vision, but in most cases it does not lead to total blindness.

The main effects of retinitis pigmentosa are:

Loss of vision during the night: People with retinitis pigmentosa may have normal or acceptable vision during the day, but they cannot see at night time. The more the disease progresses, the harder it will be to adapt to the darkness or seeing anything. That is why during the night people have to take extreme precautions to avoid accidents and avoid dark places such as cinemas or parking lots. Driving or leaving the house at night can also present a serious problem.

Tunnel vision or gradual loss of peripheral vision: As the name implies, people begin to have problems distinguishing objects that are below or to the sides because they can only see clearly towards the front. This means that the person needs to completely turn his head to focus on objects around him. When this happens people can no longer drive because they run a serious risk, it is not ideal that they walk alone at night or in little-known spaces with many objects around them that they could trip over or have accidents.

Loss of central vision: Due to the dark deposits that are forming around the retina, some people can also develop complications with central vision. They can no longer focus on objects, especially  small ones such as needles or pins and also begin to have problems reading, putting makeup on in the case of women, shaving in the case of men, sewing etc.

Retinitis pigmentosa can be prevented through genetic tests, since being a hereditary disease who suffers from it can start getting tested before having children. Unfortunately there is no cure for the disease, but one can delay it and maintain a good quality of life with certain medications and treatments.

Right now work is being done on surgeries with artificial retinas that have helped patients with a certain type of retinitis pigmentosa.

If there are people in your family who have retinitis pigmentosa and you want to be tested to prevent it, you can resort to:

  • Visual field tests. To measure lateral and central peripheral vision and know if you have any blind spots.
  • Electroretinography. This study measures how well your retinas respond to light, it works like an electrocardiogram that measures the electrical activity in your retinas.
  • Genetic testing. Undoubtedly, this type of test can help us know with greater certainty if our genes present any indications of that or another disease, and it can also give us an idea of how fast the disease will develop and if it is possible to perform some type of gene therapy to replace the affected genes.

What is diabetic retinopathy?

Maintaining high levels of glucose in the blood for many years may lead to alterations in the blood vessels of the retina, Oxygen stops being irrigated normally causing leakage of lipids and proteins, microaneurysms, ischemia and hemorrhages in the retina.

All of the above is known as diabetic retinopathy.

When oxygen does not reach the retina correctly, new blood vessels are generated to supply the deficiencies of the previous ones. Unfortunately this brings worse consequences and is known as proliferative diabetic retinopathy.

On the other hand, damage to the capillaries of the macula or central retina can cause leakage of fluid into the retinal tissue, which is known as diabetic macular edema, which can result in a very significant decrease in vision.

At first diabetic retinopathy is difficult to detect, since the first changes are not produced in the macula or central retina so at the beginning it does not affect vision but when edema develops, vision decreases and the images become blurred, that is when we can talk about symptoms.

Some symptoms may include:

  1. Decreased visual acuity
  2. Image distortion
  3. Intraocular bleeding
  4. Black spots that prevent one from seeing things clearly
  5. At its worst, blindness

How to prevent diabetic retinopathy?

Being a chronic complication caused by diabetes, the main thing is to maintain optimal glucose indexes. Maintaining a healthy weight and a healthy diet go a long way towards avoiding, not only diabetic retinopathy, but also further complications.

We must also keep our blood pressure under control, as the lack of oxygenation and blood supply directly affects the eyes.

Finally, if there are diabetic patients in your family, you could have the genes for the disease; therefore, it is important to have tests done timely to detect it in the initial stages. Although not everyone with diabetic relatives can develop it, it is best to rule the disease out in time.

Some studies that may be done to detect diabetic retinopathy include:

Contrast angiography: this study determines the condition the blood vessels

Optical coherence tomography: this serves to evaluate edema in the macula by analyzing the various layers of the retina to detect the disease even at its early stages. Even before the patient presents alterations in his vision.

If the diabetic patient has bleeding in the capillaries, the ophthalmologist may suggest starting a laser treatment to prevent the bleeding from continuing.

Macular edema is treated with antiangiogenic and corticosteroid drugs, which block the main factors of fluid leakage.

For retinal detachment, a surgery called vitrectomy is used in which the vitreum is removed, to allow the retina to rearrange itself in its original anatomical position.

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