¿Cómo se produce la retinopatía diabética?

La retina es la parte del ojo más importante para la visión. Es allí donde la luz se convierte en impulsos eléctricos para que las imágenes sean interpretadas por el cerebro. La diabetes puede llevar a un mal funcionamiento de la retina de tres formas principales:

Edema Macular: Acumulación anormal de líquido en las finas capas de la retina (en la mácula, el sitio de mayor sensibilidad de la retina). El engrosamiento de la mácula impide su función adecuada. El líquido proviene de los vasos sanguíneos cuyas paredes tienen una función inadecuada debido a la diabetes.

Hemorragia Vítrea: En fases más avanzadas de la retinopatía se forman dentro del ojo nuevos vasos sanguíneos (neovasos) que se rompen con gran facilidad. Al romperse liberan sangre dentro del ojo, lo que impide el paso de la luz hacia la retina.

Desprendimiento de Retina: También en fases avanzadas de la enfermedad, se puede desprender la retina, principalmente por tracción ejercida por el vítreo y los neovasos. Al desprenderse la retina, pierde su fuente de nutrientes y por lo tanto su función.

¿Qué síntomas ocasiona la retinopatía diabética?

Los primeros síntomas que se presentan con la retinopatía diabética son:

• Disminución de la visión nocturna.

• Pobre recuperación de visión posterior a exposición a luz brillante.

• Alteraciones en la visión de colores (principalmente azul y amarillo).

How does diabetes affect the retina?
 
Patients with diabetes are more likely to develop eye problems such as cataracts and glaucoma, but the disease’s affect on the retina is the main threat to vision.  Most patients develop diabetic changes in the retina after approximately 20 years.  Over time, diabetes affects the circulatory system of the retina. The earliest phase of the disease is known as background diabetic retinopathy. In this phase, the arteries in the retina become weakened and leak, forming small, dot-like hemorrhages. These leaking vessels often lead to swelling or edema in the retina and decreased vision. The next stage is known as proliferative diabetic retinopathy. In this stage, circulation problems cause areas of the retina to become oxygen-deprived or ischemic. New fragile vessels develop as the circulatory system attempts to maintain adequate oxygen levels within the retina, called neovascularization.  Unfortunately, these delicate vessels hemorrhage easily.  Blood may leak into the retina and vitreous, causing spots or floaters, along with decreased vision.   In the later phases of the disease, continued abnormal vessel growth and scar tissue may cause serious problems such as retina detachment and glaucoma.
 
Signs and symptoms
 
The affect of diabetic retinopathy on vision varies widely, depending on the stage of the disease. Some common symptoms of diabetic retinopathy are:
 
•Blurred vision (this is often linked to blood sugar levels)
•Floaters and flashes
•Sudden loss of vision
 
Detection and diagnosis
 
Diabetic patients require routine eye examinations so that related eye problems can be detected and treated as early as possible. Most diabetic patients are frequently examined by an internist or endocrinologist who works closely with the ophthalmologist. The diagnosis of diabetic retinopathy is made following a detailed examination of the retina with an ophthalmoscope. Fluorescein angiography and optical coherence tomography (OCT) are routinely used in the evaluation of diabetic retinopathy. Most patients with diabetic retinopathy are referred to vitreo-retinal surgeons who specialize in treating this disease. 
 
Treatment
 
Diabetic retinopathy is treated in many ways depending on the stage of the disease and the specific problem that requires attention. The retinal surgeon relies on several tests to monitor the progression of the disease and to make decisions for the appropriate treatment. These include fluorescein angiography, retinal photography, and ultrasound imaging of the eye. The abnormal growth of tiny blood vessels and the associated complication of bleeding is one of the most common problems treated by vitreo-retinal surgeons.  Laser surgery called pan retinal photocoagulation (PRP) is usually the treatment of choice for this problem. With PRP, the surgeon uses a laser to destroy oxygen-deprived retinal tissue outside of the patient’s central vision. While this creates blind spots in the peripheral vision, PRP prevents the continued growth of the fragile vessels and seals the leaking ones. The goal of the treatment is to arrest the progression of the disease. Vitrectomy is another surgery commonly needed for diabetic patients who suffer a vitreous hemorrhage (bleeding in the gel-like substance that fills the center of the eye). During a vitrectomy, the retina surgeon carefully removes blood and vitreous fluid from the eye, and replaces it with clear salt solution (saline). At the same time, the surgeon may also gently cut strands of vitreous attached to the retina that create traction and could lead to retinal detachment or tears. Patients with diabetes are at greater risk of developing retinal tears and detachment. Tears are often sealed with laser surgery. Retinal detachment requires surgical treatment to reattach the retina to the back of the eye. The prognosis for visual recovery is dependent on the severity of the detachment.
 
Prevention
 
Researchers have found that diabetic patients who are able to maintain appropriate blood sugar levels have fewer eye problems than those with poor control. Diet and exercise play important roles in the overall health of those with diabetes.  Diabetics can greatly reduce the possibility of eye complications by scheduling routine examinations with an ophthalmologist.  Many vision problems can be treated with much greater success when caught early.