Vitreo-Retinal Diseases
The retina is a light-sensitive layer of tissue
The retina is a light-sensitive layer of tissue, lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina. Light striking the retina trigger nerve impulses that are sent to various visual centers of the brain through the fibers of the optic nerve.
The retina is a very delicate tissue that can be affected by many pathologies, both ocular or systemic. Local diseases include retinal detachment, age-related macular degeneration, uveitis and high myopia. Systemic diseases that can affect the retina are diabetes, systemic hypertension, and several collagen diseases.
DIAGNOSTIC METHODS
Ophthalmoscopy: is the direct examination of the retina after dilating the pupil. It is the basic and first diagnostic examination of the retina. With the use of specially designed photographic cameras we can obtain high resolution images of the retina (Retinography) to allow for precise comparison and evaluation of changes over time.
In Fluorescein Angiography and Indocianin Green Angiography we inject a contrast in a vein of the arm, and then we take sequential images of the flow of the contrast through the arteries and veins of the retina, allowing for a detailed examination of the vascular system of the retina and choroid.
Optical Coherence Tomography (OCT) is an examination method that obtains three-dimensional images at 5 microns resolution of the retina. It is presently the most sophisticated and precise method of examining the structure of the retina.
In patients with opaque media, where ophthalmoscopy is not possible, we can use an Ecography B, to analyze the position of the retina and detect some pathologies as hemorrhages, intraocular tumors, or retinal detachment.
DIABETIC RETINOPATHY (DR)
What is?
Long term diabetes can damage the small vessels in the eye, specially in the retina.
In the first stages, some small dilatations of the retinal capillaries appear. These microaneurisms have no functional effect on vision, but represent the first indication of retinal damage by diabetes. With time there can be hemorrhages, exudates, and new vessels formation.
Treatment
If left untreated a diabetic retinopathy is progressive and represents a vision-threatening condition. The examination of the retina at a yearly interval is fundamental to evaluate and detect the first symptoms of diabetic retinopathy and start the treatment in the early stages.
Argon laser photocoagulation is the initial treatment. The coagulation of the vascular anomalies can reduce hemorrhages and prevent fluid accumulation in the retina.
Intraocular injection of corticoids or anti-VEGF medications can be effective in reducing retinal edema and improving visual function.
In advanced cases the only possibility is surgical treatment by means of a Vitrectomy.
AGE-RELATED MACULAR DEGENERATION (AMD)
What is?
Age-related macular degeneration is a degenerative condition that affects the center of the retina, an area called “macula”. The macula is the area of the retina with the higher density of sensitive cells (the cones) and therefore responsible of the vision of detail and colors.
AMD can adopt two forms: the dry form which is the most frequent, and the wet form. The dry form is more slowly progressive, while the wet form is more acute in its onset. In the final stages of both forms there is a loss of central vision.
The exact cause of this disease is not known but there are predisposing factors. Age is the most important factor: 30% of patients over 75 years have AMD in different stages. Other known factors include family history, smoking tobacco, fat intake, exposure to sunlight, and gene mutation.
Treatment
The available treatments are very limited. It is recommended to avoid predisposing factors and take anti-oxidative nutritional supplements.
In the wet form intravitreal inyection of anti-VEGF substances (Avastin, Lucentis) can improve the situation and stabilize the disease.
Genetic testing in AMD
Genetic factors are the leading cause (70%) of development of the disease. Presently there are more than 600.000 people with AMD in Spain and more than 3.000.000 are in high risk of suffering it.
Genetic testing done in a simple saliva sample, can predict the probability of suffering the disease. In these patients dietary counseling, nutritional supplements, avoiding risk factors as smoking, and frequent eye examination allows for some prevention and early treatment of the AMD, reducing the visual impact.
RETINAL DETACHMENT (RD)
What is?
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.
Retinal detachment can be rhegmatogenous (caused by a retinal break or hole), exudative (accumulation of fluid underneath the retina by inflammation, vascular anomalies or tumors) or tractional (membranes over the retina that pulls the retina from the other layers).
The symptoms of a retinal detachment can be sudden appearance of light flashes or floaters, the impression that a veil or curtain was drawn over the field of vision, or central visual loss.
Treatment
In the rhegmatogenous and tractional retinal detachments treatment is always surgical and in an emergency basis. Vitrectomy combined with other techniques as encircling bands or gas tamponade are the treatment of choice.
In exudative or secondary retinal detachments, the treatment will depend on the cause of the detachment, and very often is a medical treatment what is needed.