How Does The Retina Function
The human eye works like a camera. The retina, which is a thin membrane that entirely covers the eye fundus, is the film. Its task is to transform the visual stimuli into nerve pulses that are sent to the brain. Under the retina, there is a vascular layer called the choroid, which nourishes the deep layers that are formed by millions of light-sensitive cells (photoreceptors). The photoreceptors in the central retina or the macula (cones) are responsible for daylight vision, the decoding of particulars and color perception. The photoreceptors placed in the periphery (rods) are responsible for peripheral and night vision. The photoreceptors turn light into nerve pulses that are processed by many other retinal cells and arranged on layers. The extensions of the most superficial cells act as optical fibers that congregate in the optical nerve to send visual information to the brain. In practical terms, all our actions crucially depend on one retinal area, the fovea (the center of the macula) where both the thickness and the diameter are lower than half a millimeter.
Macular Pucker, Macular Hole, Macular Degeneration
The abnormal development of a translucent membrane over the retina (macular pucker), macular hole and age-related macular degeneration are among the most widespread diseases that affect the central portion of the retina called the macula.
Macular Pucker And Macular Hole
Macular puckers and macular holes are caused by alterations of the vitreous, a transparent and gelatinous substance that fills the interior of the eye. Over time the vitreous can suffer from liquefaction and degeneration, which culminate with its separation from the retina.
How Is Macular Pucker And Macular Hole Treated
The surgeon can remove the vitreous humor through a procedure called vitrectomy if it causes dangerous tractions on the retina or if there is the need to treat a diseased retina. According to the surgical goal, the partial or total removal of the vitreous humor is combined with other procedures. The minimally invasive vitreoretinal surgery leads to improved visual capacity. The results depend on the involvement of the retina (intensity and duration of the disease). They can be slow or incomplete. In the Blue Eye Ocular Microsurgery Center, one may undergo operation under local anesthesia and have the macular pucker removed. The operation is carried out in day surgery, lasts 30 minutes, and is practically painless.
In the age-related macular degeneration (AMD), the cells of the macula responsible for the central vision degenerate, eventually, die and are replaced by scar tissue devoid of functionality.
The macula is responsible for over 35% of the visual field, so a serious case affects the performance of normal day-to-day activities with inevitable consequences on the psychological dispositions of the patient. Peripheral vision, however, is intact and is not at risk.
The AMD, therefore, does not cause complete blindness and it is possible to return to performing certain occupations independently and productively by resorting to visual rehabilitation techniques. The visual re-education of the AMD uses expedients (such as halogen lamps), magnifying tools, closed-circuit televisions, special telescopic systems and a series of techniques for environmental adaptation so as to maximize the residual potential of the peripheral retina.
There are two forms of AMD
- Wet Form: Approximately 10% of people with AMD develops this. Some blood vessels grow abnormally in the retinal wall beneath the macula. The accumulation of blood and fluid in the eye can be treated to prevent a rapid deterioration of vision. An early treatment allows limiting the damage. However, a permanent scar remains.
- Atrophic Or Dry Form: Approximately 90% of patients with atrophic AMD has a form determined by the accumulation of cellular waste that if you do not reabsorb can calcify causing injury.
How Is Macular Degeneration Treated
Unfortunately, it is impossible to restore the vision of all those who suffer from age-related macular degeneration (AMD), however, the therapies currently available can significantly halt the progression of the disease.
For several years, intravitreal injections of anti-VEGF drugs are used to block or inhibit the proliferation of abnormal blood vessels.
This therapy is done in the surgery room, the drug is injected into the vitreous after instillation of a few drops of anesthesia. The procedure takes a few minutes and the patient can return home.
The functional results are satisfactory, the disease is blocked and in the best cases, there is also a partial recovery of lost vision.
In some cases, it may also have to recourse to a surgical treatment.
Ophthalmologists and low-vision specialists have developed a special system of lenses to improve central vision. The IOL-Vip Revolution is the combination of two small lenses that are implanted by the surgeon in place of the crystalline lens. They act like a real telescope, magnifying the image slightly on the retina directing it toward a healthy part. To evaluate the visual improvement potential before surgery, the treatment is simulated with an external optical device that reproduces the effect of the two lenses and their prismatic magnification. Patients are helped to manage the new vision with a few simple exercises that can then also be performed at home. The procedure does not require hospitalization and is performed under local anesthesia.
It must, however, be pointed out that the selection of possible candidates is very strict. In fact, this technique can not be extended to all visually impaired. Also, after surgery, rehabilitation is long and demanding.