In short: diabetic retinopathy
Diabetic retinopathy is a complication of diabetes that damages retinal blood vessels. The typical microvascular alterations that characterize this disease arise with a predictable progression and this prevents serious visual damage. In fact, if neglected, diabetic retinopathy can cause severe vision loss or even blindness.
Diagnosis
Proliferative retinopathy and macular edema can develop in the absence of warning symptoms. However, the advanced stage of the disease and the involvement of the macula are associated with a high risk of vision loss, which in many cases cannot be reversed. Therefore, even if the vision does not seem to be compromised, every diabetic patient should regularly undergo a simple examination of the fundus. If the presence of diabetic retinopathy is confirmed during the diagnostic tests, the patient is informed about the severity of the condition and what treatment can be adopted.
The diagnosis of diabetic retinopathy is confirmed by a complete examination of the eye.
Examination of the ocular fundus
The fundus examination uses a mydriatic eye drop to dilate the pupils and allow the ophthalmologist to examine the retina, blood vessels and optic nerve.
During the exam, the eye specialist can find:
- Losses from blood vessels.
- Swelling of the retina (macular edema);
- Presence or absence of cataracts;
- Lipid deposits on the retina;
- Growth of new blood vessels and scar tissue;
- Bleeding in the vitreous (emovitreo);
- Retinal detachment;
- Any modification of blood vessels;
- Anomalies of the optic nerve.
As an addition to the exam, the ophthalmologist can perform:
- Visual acuity test, to assess the extent to which the patient is able to distinguish the details and shape of objects at various distances.
- Slit lamp examination, to examine the anterior part of the eye, including eyelids, conjunctiva, sclera, cornea, iris, crystalline lens, retina and optic nerve.
- Tonometry, to determine the ocular pressure.
Angiography with fluorescein (fluorangiography)
If necessary, the doctor can perform angiography with fluorescein to further examine the retina.
Fluorangiography uses a special dye (fluorescein sodium) which is injected into a vein in the arm; in this way, when fluorescein crosses the retina, the doctor can obtain images that frame the state of the blood vessels supplying the eye.
Fluorangiography shows in detail:
- Occluded blood vessels and areas of the ischemic retina;
- New-formed blood vessels;
- microaneurysms;
- Possible macular edema.
This diagnostic procedure is also fundamental to create a sort of map, useful in anticipation of therapeutic laser interventions.
Optical coherence tomography (OCT)
Optical coherence tomography (OCT) is a non-invasive imaging test that provides high-resolution images of retinal tissue, assesses its thickness and provides information about the presence of a possible fluid or blood spill. The examination is particularly useful for studying the macular region and the presence and severity of the edema. Subsequently, the results obtained with optical coherence tomography can be used to monitor whether the treatment is working effectively.
Ocular ultrasound
If the patient has a hemorrhage of the vitreous, the ophthalmologist can proceed with an ultrasound examination that uses high frequency ultrasounds, used to examine the ocular structures not otherwise visible. The ultrasound can "see" through the hemovitreus and determine if the retina is detached. If the detachment of the retinal tissue is close to the macular region, timely surgery is often necessary.
When to schedule an eye examination
Diabetic retinopathy develops years after the onset of diabetes mellitus. For this it is important to undergo regular eye exams, which indicatively respect the following schedule:
- type 1 diabetes : within five years of being diagnosed with diabetes, then annually.
- Type 2 diabetes : every year, from the time of diagnosis of diabetes.
- During pregnancy : if a diabetic patient becomes pregnant, she should make an appointment with her eye doctor in the first trimester of pregnancy. Additional eye tests may be recommended throughout gestation, as diabetic retinopathy can progress rapidly during this state.
In any case, the frequency remains in the eye of the ophthalmologist and is related to the appearance of signs of diabetic retinopathy and to the severity of the retinal picture. In the event of sudden changes in visual function, it is advisable to consult a doctor immediately (for example: if the disorder affects only one eye, it lasts more than a couple of days and is not associated with an alteration of the blood sugar).
Treatment
The best medical intervention for diabetic retinopathy is to prevent its occurrence through proper diabetes management. Careful monitoring of blood glucose, blood pressure and cholesterol can help limit vision damage and significantly reduce the risk of losing sight in the long term.
Treatment depends largely on the severity of diabetic retinopathy. For example, if this is identified in the early stages, no immediate intervention may be necessary and the management of the disease may be based simply on more effective control of diabetes. A patient with mild non-proliferative retinopathy should have regular vision checks (once or twice a year) so that the condition can be carefully monitored. In the case of proliferative retinopathy and macular edema, laser treatment (photocoagulation) may be recommended. This can be used in the presence of a noticeable discharge of blood into the eye, to reduce the growth of new fragile vessels and prevent vision loss. Alternatively, therapy that includes intravitreal anti-VEGF injections may be recommended. If laser treatment is not possible because diabetic retinopathy is too advanced, it is possible to resort to vitrectomy. Surgery often slows or stops the progression of diabetic retinopathy, but is not a cure. Diabetes is a chronic condition: even after treatment for diabetic retinopathy, the patient will have to undergo regular eye exams and, at some point, further treatment may be necessary.
Laser surgery
Laser treatment (known as photocoagulation ) can slow or stop the development of diabetic retinopathy. Photocoagulation is often recommended for patients with macular edema, proliferative diabetic retinopathy (PDR) and neovascular glaucoma. Before the procedure, a local anesthetic is administered to numb the surface of the eye and eye drops to dilate the pupils. A special contact lens is temporarily placed on the eye, in order to focus the laser light on the retina with millimeter precision. The main objective of the treatment consists in preventing vision loss, stopping or slowing the flow of blood and fluid in the eye, reducing the severity of macular edema and preventing the formation of new abnormal vessels on the retina. The procedure is usually not painful, but the patient may feel a tingling sensation when certain retinal areas are treated. After treatment, vision may be blurred, but should return to normal after a few hours. Sometimes, photocoagulation can reduce night and peripheral vision (lateral vision).
In proliferative diabetic retinopathy, the laser can be focused on all parts of the retina (except macula), in two or more sessions ( panretinal photocoagulation ). This treatment reduces the newly formed vessels and often prevents them from growing in the future. Panretinal photocoagulation has been shown to be very effective in preventing vitreous bleeding and retinal detachment.
Vitrectomy
Vitreo-retinal surgery is an invasive procedure that is used in the event of:
- Severe intraocular bleeding (a large amount of blood is collected inside the eye, obscuring the view);
- Extensive areas of scar tissue and retinal detachment (scar tissue can cause or have already caused retinal detachment).
During vitrectomy, a surgical microscope and some micro-probes are used to remove blood, vitreous fluid and scar tissue. The vitreous humor removed from the inside of the eye is replaced with a gas or a silicone oil, to help keep the retina in place. Removal of scar tissue helps the retina to return to its normal position. Vitrectomy often prevents vitreous bleeding by removing the responsible abnormal vessels. The procedure ended with photocoagulation, to ensure that the retina permanently maintains the correct position. The gas or liquid will gradually be absorbed by the body, which will create a new vitreous gel to replace the one removed during surgery.
Intravitreal injection of drugs
In some cases, an anti-VEGF drug may be given to help treat diabetic retinopathy. This medicine blocks the activity of the vascular endothelial growth factor, or VEGF, by inhibiting the formation of new blood vessels and favoring their reabsorption. Intravitreal anti-VEGF injections are often used to treat age-related macular degeneration (AMD); however, research has shown that they can also help reduce neovascularization in people with diabetic retinopathy. Intravitreal anti-VEGF injections are administered by an ophthalmologist on an outpatient basis. After dilation of the pupil and administration of a local anesthetic, the drug is injected into the vitreous humor. The drug reduces swelling, exudates and unwanted growth of blood vessels in the retina. At the end of the procedure the ocular pressure is measured, which may increase after the injection and may require medical intervention if it is not within the normal range. About a month after the administration of the anti-VEGF drug, the patient should note the effects of the therapy on vision. The treatments can be administered only once or in a series of injections at regular intervals, usually about every four to six weeks or as set by the doctor. Intravitreal injection of drugs appears to be a promising therapeutic procedure, but has not yet been evaluated in long-term clinical trials.
Prevention
The risk of developing diabetic retinopathy can be reduced by adopting the following strategies:
- Regular eye exams: vision reduction and blindness can be prevented through early diagnosis and timely treatment. It is important to act before the eye problems are evident and the retina is too severe.
- Effective management of diabetes: an accurate metabolic control of glycaemia and strict compliance with diabetes management therapy (with insulin or oral antidiabetic agents) can prevent the onset and progression of diabetic retinopathy.
