Medical information gathered by Dr. Marco Abbondanza on experience with ocular surgery


RETINA


The internal membrane of the eye or retina is made up of nervous cells and arterial and venous vases which serve as its nutrition.
Many problems can arise regarding the nervous or circulatory part of the retina. The same problems can be found in the center alone, the perimeter or the entire retina.
Following are the most common symptoms and pathologies to help understand any unusual sensations one might feel.


Diabetic retinopathy

Diabetes is a systemic illness which affects the whole human organism. Since diabetes invades the circulatory blood system, the retina, extremely rich with blood, is also affected. The gravity of the illness can be proportioned to its length and the glycaemia quality control.
20% of legally blind persons between 20-65 years of age suffer from diabetic retinopathy, one of the main causes of blindness in the western world. Due to a weaker flow of oxygen, the cells degenerate and circulation decreases causing damage to the retina. If the situation continues, our body will try to create new blood vessels in order to increase oxygenation. These new vessels are very fragile and subject to many breaks with consequential retinal hemorrhages. The blood which overflows from the vessels forms membranes which bring on retinal detachment.
The above represents an extreme situation of neglect whereas accurate check-ups by both ophthalmologist and patient would allow good vision to be maintained.
In order to keep the retina under control, a check-up of the fundus oculi, fluoroangiography must be done.
If vascular problems arise, photocoagulation with laser can be used on the new retinal vessels since this can put an end to other vascular alterations.
The latest therapies use laser capable of attacking only the membrane which has formed on the central part of the retina. These are called PDT and TTT.


Senile macular degeneration

The macular is the central part of the retina which is affected by the illness called senile macular degeneration. The most important part of the retinal tissue, the macular, is the only part containing receptors called cones, which give refined vision and sensitivity to the eye for reading purposes and for distinguishing tiny details. This illness normally appears after age sixty but can be found in young persons having a high degree of myopia.
It is usually caused by changes in circulation which is why toxic substances produced by the activity of single cells are not eliminated. These substances end up damaging and then destroying the cells.
Another name for this illness is age related macular degeneration. The first sign of this illness is a distorted vision of objects, followed by central scotoma, that is, a dark area which intervenes with vision. Blindness will never occur since peripheral vision will not worsen. Diagnosis is obtained through the fundus oculi exam especially through fluoroangiography.
Often sub-retinal neo vascularization can be associated to this illness. These new vessels bring on more problems and should therefore be eliminated through laser therapy. It is very important that problems related to retinal circulation be prevented in time since this is a difficult pathology to overcome.
Once this problem has set in, use of medication to better the metabolism of retinal cells along with medication to better retinal circulation is very important. Laser therapy on the new vessels is often helpful.
Laser therapies most frequently used are photocoagulation with Argon laser, PDT and TTT.


Retinal circulation problems

The retina is covered by arteries and veins which originate from the division of smaller branches of the central retinal artery and of the retina's central vein.
The most important pathologies which can strike these formations are: Occlusion of the central retinal artery and Occlusion of the retina's central vein.


Occlusion of the central retinal artery (ACR)
Total, partial, enduring or temporary occlusion can occur for several reasons: changes in blood coagulation as in thrombosis or general illness like diabetes and arteriosclerosis. With complete occlusion comes retinal deterioration and sudden blindness. Partial occlusion brings reduced vision on the area.
Fluoroangiography is the best possible test to find the occlusion. The best solution is rapid and precise medical therapy.


Occlusion of the central retinal vein (VCR)
The central retinal vein can also be partially or totally affected by this illness.
Occlusion of one branch is more prone to happen than complete occlusion. Where there is an illness such as diabetes, arteriosclerosis or artery hypertension this is more common. There is a rapid decrease in vision which can become total depending on the amount of occlusion.
Medication is the best therapy and sometimes argon laser is used to avoid the risk of developing new blood vessels which cause new chain hemorrhages.


Retinal detachment
The retina is the nervous part of the eye which "captures" images and sends them to the brain. The retina must be "perfectly normal" in order for it to work well, resting its base on the choroid and being normally served by arteries and veins.
Should the retina become detached from its base, it would have inadequate circulation and nutrition and slowly die.
Retinal detachment involves part or all of the retina.
There are four main reasons for retinal detachment: myopia (the higher the case of myopia, the higher the risk of retinal detachment), head and eye trauma, systemic illnesses such as diabetes and hypertension and some ocular operations.


How can we distinguish retinal detachment?
Symptoms vary according to the degree of retinal detachment. If the lesion is small, this problem can go without notice, becoming visible only through an accurate check-up. Small dark moving spots, flashes or blurred vision may appear. Part of the field of vision can diminish in more serious cases.
An exam of the fundus oculi and the visual field are the best tests for correct diagnosis when the crystalline is transparent. If this is not the case, an ocular sonogram will help expose the otherwise invisible retina.


Retinal detachment therapy
Argon laser can close the hole permanently in cases where there is a slight detachment. Surgery is necessary in more serious cases. This can be performed either internally or externally using local or general anesthesia. Sometimes chemical substances (silicon oil, perfluor carbonate, etc.) are necessary to replace the retina on its base. Should these substances be used, another operation will have to be performed to remove and substitute these with others which our organism can tolerate for a longer time.