The retina is the layer of tissue sensitive to light that is located on the posterior inner part of the eye and acts like a film in a camera: The images pass through the eye's lens and are focused in the retina. The retina then turns these images into electric signs and sends them through an optic nerve to the brain.
Retina and vitreous problems can cause severe eyesight loss and even blindness.
The most common pathologies affecting the vitreous-retina set are:
It is a severe visual problem, that entails the total loss of vision if not operated on. It consists of the separation of the retina from its usual location, and although in some cases its origin may be traumathological, inflammatory, appear after eye infections or be related to genetic alterations affecting the eye, in most cases it is due to the appearance of one or several breaks in the retina after a vitreous detachment.
They are more frequent in eyes with myopia, as these have weak areas in the border zones of the retina and therefore, have more breakages at this level, although it may happen to any person.
If the retina breaks during a vitreous detachment we have a entry point for the liquefied vitreous to introduce and detach the retina.
The symptoms of a vitreous detachment is vision loss. Yet this occurs in a very characteristic way. Firstly, it is often preceded by the typical symptoms of a vitreous detachment, that is, the flying "flies" and flashes of light, and the a dark area usually appears in the border of the field of vision, either at the top, bottom or sides, that slowly progresses and leaves us without being able to see in this area. For example, the patient may lose the lower field of view although he/she still sees in the lower part. If action is not taken, the entire vision is lost.
If a patient starts having symptoms of vitreous detachment it is important that he/she attends the ophthalmologist as soon as possible to rule out a break or tear in the retina. If we see a tear before the retinal detachment has taken place, it is easy to treat it with laser without the need of surgery.
Once the retina has detached, the only solution is to undergo surgery.
The interior part of the eye is filled with vitreous humor. This vitreous humor or liquid is mainly made up of collagen, water and hyaluron acid, it has a gel-like consistency and it is adhered to the surface of the retina. As we grow older, the consistency of the vitreous humor is increasingly more liquid, so that it moves increasingly freely inside the eye when this moves. When we are around the age of 50, and from then onwards, we will all undergo an experience named vitreous detachment. As the vitreous is very liquid and moves freely inside the eye, there comes a moment when it detaches from the retina and tends to collapse inside the eye. This takes place more or less suddenly and usually causes two specific symptoms: The sudden appearance of material floating inside the eye that patients describe as "flies", clouds, cobwebs, etc. and seeing lights described as flashing lights, glares or semicircular lights, that usually appear in the outer part of the eye and especially at night or low light conditions and that are known as photopsia.
In most cases, the photopsias end up by disappearing and the “flies” improve with time until becoming almost invisible, although in some cases they can be very disturbing, so much , that sometimes a vitrectomy is necessary to remove them.
In a high percentage of patients, the vitreous detachments does not entail a serious problem, yet in some cases, as the vitreous detaches from the retina, it can pull it and break it, which entails a high risk of suffering a retina detachment.
Age-related macular degeneration
The macula is the central part of the retina, the area with the best vision. Age-related macular degeneration (AMD), as its name indicates, is a disease affecting the macula, it is degenerative and affects people older than 50 years of age. It worsens with age and is quite frequent; it is considered that approximately one third of the population older than 70 has some degree of macular degeneration.
The disease has two ways of evolving
- Dry form. Approximately 80% of patients affected have a dry form throughout all their life. This entails an involvement of the macula that progresses slowly over the years and that usually starts with the appearance of white deposits in the macula named drusen. At a later age it can seriously affect the vision, yet a long time passes from when the disease starts until it reaches more serious stages, with a progressive deterioration of the vision that happens very slowly over the years.
- Wet form. Between 15% and 20% of patients develop the wet form at some stage of the development of the disease. It consists of the appearance of small abnormal blood vessels in the macula, known as neovessels, that lose liquid or blood in the macula, causing this to deform and for the appearance of fluid-filled cysts inside the macula or under it. From a clinical point of view, it is quite different from a dry form, as in this case the loss of vision takes place quickly, sometimes even suddenly, and is usually accompanied by a characteristic symptom which is the deformity of the image or the appearance of a central blotch in the vision. It is very important for the patient to swiftly attend visit an ophthalmologist in the case of having these symptoms, as he/she could be developing a wet form of AMD and must receive treatment as soon as possible. The wet form does have treatment, that intends to improve the vision, or at least stop the loss of it.
Diabetic retinopathy is a condition of the retina that results as a complication of diabetes. It affects patients with diabetes type 1 and 2 and is still today, one of the main causes of vision loss and even blindness.
Diabetes affects the retina in the same way as the rest of the body, mainly altering the retina circulation. It can cause for the blood vessels to lose liquid and for this to accumulate in the macula, giving rise to macular oedema, that is, an accumulation of liquid in the macula, and this is the main cause of vision loss in diabetic retinopathy, yet it can also give rise to the gradual closure of small blood vessels that leave areas of the retinal without blood irrigation, which is known as retinal ischemia. If the ischemia affects the macula this causes a vision loss that is almost impossible to treat.
Yet if the ischemia takes place in the periphery of the retina it could give rise to the appearance of newly formed blood vessels, known as neovessels that can cause serious complications, such as bleeding inside the eye, vitreous haemorrhages, tractional retinal detachments, and even a glaucoma very difficult to treat known as neovascular glaucoma, that can cause a significant increase of the eye pressure that can also cause blindness. To evaluate the state of the retina of diabetic patients it is usually necessary to perform an angiography with a contrast named fluorescein and that is known as AFG.
On some occasions a vitreous detachment occurs that is not complete, remaining adhered to the macular area and pulling it. It therefore tends to lift it, which entails a loss of vision. It is easily diagnosed by performing an optic coherence tomography, known as OCT, which is a type of scan of the macula. If this vitreous adherence to the macula does not release spontaneously and the vision progressively decreases, a vitrectomy must be conducted to release it and for the macula to return to its original position.
A continued vitreousmacular traction may give rise to a hole in the macula. It is characterised by the appearance of loss of vision in the central part and may be also accompanied by a slight image deformity. It is also easily diagnosed with an OCT. If it is not operated, the macular hole will get bigger with time, and the loss of vision will be increasingly higher.
In the eye there are four main veins that join in a central vein; any of them may suffer a thrombosis, although these are frequent in patients with ocular hypertension or with some of the known cardiovascular risks, such as, high blood pressure, diabetes, high cholesterol or triglycerides, etc.
The visual affectation depends on what vein thromboses. It is very serious if it affects the central vein of the retina and less serious if it affects one of the four single veins. The vascular involvement of the area affected is similar to that produced in the diabetic retinopathy and the treatment is also similar, as laser can be used, as well as anti-angiogenetic drugs or intraocular corticosteroids or even surgical treatment, in the case of serious intraocular bleeding.
This is a membrane that develops on the surface of the macula, causing it to progressively wrinkle. It is much more frequent in people older than 60 and its cause is mainly idiopathic, although it can appear in connection to other pathologies such as thrombosis, diabetes, secondary to laser treatment, surgery or traumatisms. As it develops, is slowly wrinkles the macula causing decreased vision and image deformity. It requires surgical treatment.