RETINAL DISEASES: DIAGNOSIS, THERAPY AND SURGERY
The internal membrane of the eye or retina is constituted of nervous cells and arterial and venous vessels which provide nutrition and oxygenation to the retinal cells. Many diseases can affect the nervous or circulatory part of the retina. The same disorders can occur in the central area, the perimeter, or the entire retina. The following is a list of the most common disorders and associated common symptoms, and may help patients understand any unusual visual sensations they experience associated with retinal disease.
Dr. Abbondanza has been performing medical treatments and innovative surgery for retinal diseases for over 30 years, becoming one of the most experienced surgeons in this field.
Diabetic Retinopathy
Diabetes is a systemic illness affecting the entire organism. Since diabetes affects the circulatory blood system, the retina which is an highly vascular tissue is also affected. The entity of the damage is proportionate to the duration of the disease and also to blood glucose level control.
20% of legally blind persons between 20-65 years of age are affected with diabetic retinopathy, which is one of the leading causes of blindness in the western world. Due to a weaker flow of oxygen caused by altered circulation of the retina, the retinal cells are damaged. If the disease progresses, new and fragile blood vessels may appear as a reaction/compensatory stimulus aiming to increase oxygenation. However, these new vessels are very fragile and may cause retinal hemorrhages. In advanced diabetic retinopathy retinal hemorrhages may ultimately contribute to the formation of neovascular membranes which increase the possibility of retinal detachment.
The above description depicts an extreme situation of neglect, ideally, regular ocular check-ups including ophthalmoscopic retinal examination and retinal angiography (fluoroangiography) must be performed by diabetic patients.
If vascular problems develop, laser photocoagulation can be applied on the retina to inhibit the formation of new retinal vessels and to reduce vascular alterations and complications.
The most recent advances consist in specific laser treatments that are capable of eliminating the membrane which has formed on the central part of the retina. These treatments are known as PDT and TTT.
Senile macular degeneration
The macula is the most visually important area of the retina, this structure may be affected by a disease known as senile or age-related macular degeneration. The macula is the only part of the retina that contains specific receptors called cones, these receptors provide detailed vision and are necessary for precise visual activities such as reading.
This disease normally appears after age sixty but may also affect young patients affected with high degrees of myopia.
It is usually caused by alterations of retinal circulation, that do not allow efficient removal of the by-products of metabolism. These substances may damage and ultimately destroy the retinal cells.
The first symptoms consists in distorted vision of small objects and problems during precise activities such as reading, followed by central scotoma, which is perceived by the patient as a dark or blurred area of vision. Fortunately, blindness never occurs since peripheral vision is never affected. Diagnosis is obtained by the fundus oculi exam, and especially by fluoroscein angiography.
Often sub-retinal neo- vascularization is associated with senile macular degeneration. The new fragile vessels may complicate the disease and should be eliminated through laser treatment. It is important to treat problems that affect retinal circulation on time to prevent further complications, considering that this is a difficult pathology to overcome.
The use of medications to improve the cellular metabolism of retinal cells along with treatment to improve retinal circulation are very important. Laser therapy on the new vessels is often helpful.
The laser treatments frequently adopted are photocoagulation with Argon laser, PDT and TTT.
Retinal circulation problems
The retina is richly supplied by arteries and veins which originate from branches of the central retinal artery and of the retina’s central vein. The most important diseases that affect these vessels 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: alterations and diseases affecting blood coagulation, general diseases such as diabetes, and vascular conditions such as arteriosclerosis. In central retinal arterial occlusion, retinal ischemia and sudden blindness may occur. Partial vascular occlusion results in reduced vision in the affected area.
Fluoroscein angiography is the best possible test to define the occlusion. The best therapy is appropriate and rapid medical treatment aiming to reduce the ischemic damage to the retina.
Occlusion of the central retinal vein (VCR)
The central retinal vein can also be partially or totally affected by occlusion.
Occlusion of one branch is more likely to occur than complete occlusion. Again, underlying general medical conditions such as diabetes, arteriosclerosis or arterial hypertension are common. The symptoms consist in a sudden decrease in vision of variable degree, depending on the amount of occlusion.
Therapy consists in appropriate and immediate medical treatment, sometimes argon laser is used to avoid the risk of developing new blood vessels which may cause new chain hemorrhages.
Retinal detachment
The retina represents the nervous tissue of the eye, it “captures” images and sends visual stimuli to the brain. Normally, the retina is attached to an underlying vascular membrane called the choroid. Should the retina be detached from this underlying base for a long period of time, inadequate circulation and consequent death of retinal cells would result.
Retinal detachment may involve a part, or all, of the retina. There are four main causes of retinal detachment: myopia (higher myopia increases risk of retinal detachment proportionately), head and eye trauma, systemic illnesses such as diabetes or complications of ocular surgery.
How can we recognize retinal detachment?
Symptoms vary according to the degree of retinal detachment. If the lesion is small, the problem may not be noticed by the patient and be apparent only through a complete retinal examination. Small dark moving spots, flashes or blurred vision may appear as initial symptoms. Part of the field of vision can diminish in the more serious cases. An examination of the retina and the visual field are the best tests for diagnosis when the crystalline is transparent. When the inner ocular structures are not directly visible by direct retinal examination, an ocular ultrasonic sonogram must be performed to visualize the retina.
Retinal detachment treatment
Argon laser can close the retinal hole/break permanently in cases where there is a very slight detachment. Surgery is necessary in more serious cases. This can be performed either by internal or external application using local or general anesthesia. Sometimes chemical substances (silicon oil, perfluor carbonate, etc.) are necessary to reposition 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.
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