Detection and Diagnosis

Functional vision can be preserved or restored in many patients with even severe disease. However, accurate & timely detection of retinopathy remains a major problem as serious retinopathy can be present without symptoms. Therefore, a diabetic should be aware of the risks & have their eyes (& retina) examined regularly as suggested below –

Age of  onset of Diabetes Mellitus Recommended time of First Examination Routine minimum follow up (more frequent in case of abnormal findings)
0 – 30 years    5 years after onset     Yearly
31 years and  above    At the time of diagnosis     Yearly

Some studies have shown that pregnancy may aggravate existing retinopathy. To minimise potential visual loss, a retinal examination is recommended in diabetic patient during the first trimester & every 3 months thereafter.

Besides the routine examination, to detect diabetic retinopathy, the inner part of the eye has to be examined using an instrument called Indirect Ophthalmoscope. If diabetic retinopathy is noted, depending on the need, special tests may have to be performed. These include Fundus Fluorescein Angiography (FFA)Optical Coherence Tomography (OCT) and Ultrasonography (USG).

During FFA, a fluorescent dye is injected into a vein in the arm. Photographs of the retina are taken in rapid succession as the dye passes through the retinal blood vessels. This test is used to detect the sites of leakage in the retina or the presence of new blood vessels thereby helping to determine if treatment is necessary.

OCT is a new and very useful diagnostic tool in which a beam of light is used to scan the central area of retina (Macula). This gives a cut sectional view of retina and a detailed picture of retinal structure can be seen. This helps in detection of extent of fluid in the retina as well as any traction and also to judge the response of treatment.

Ultrasonography is a non-invasive diagnostic test utilizing ultrasonic waves. This test is used to rule out presence of tractional retinal detachment in eyes with vitreous haemorrhage or cataract.

Treatment:

Not all cases of diabetic retinopathy require treatment. Several factors such as patient’s age, history and degree of damage to the retina have to be considered before deciding for the treatment.

Many studies have shown that good control over glucose levels delays the onset & decreases the severity of retinopathy. Numerous drugs have been tried in an effort to alter the course of retinopathy, but none of these have shown to be effective in arresting or reversing the retinopathy. Diabetic retinopathy is frequently found in conjunction with hypertension. Controlling hypertension may also help the retinopathy from becoming worse.

Laser Photocoagulation  is the most important mode of treatment of diabetic retinopathy. Laser beam is used to seal the leaking vessels and destroy the new vessels. It must be remembered that laser treatment is performed to maintain vision and NOT to improve it. Hence, to be most helpful, the laser treatment must be delivered before patient complains of visual loss.

Laser treatment does not require hospitalisation and is performed on an out-patient basis. It may be performed in one sitting or may have to be repeated depending upon the severity of the retinopathy. After photocoagulation, patient is asked not to bend down, not to strain or lift heavy objects at least for 3-4 weeks, to sleep with head raised using 2-3 pillows and to control coughing and sneezing with appropriate medicines.

Laser photocoagulation is very safe and essential with negligible side effects if any.

Intravitreal Injections :  In certain conditions, where laser is not possible or is not effective, certain medicines are now used in form of injections in the eye. This is a painless procedure and done in operation theatre to ensure sterility. This form of treatment may also be combined with either laser or surgery.

Vitrctomy : In most cases disease is controlled by laser but more than one sitting may be required. In some patients with advanced proliferative diabetic retinopathy, extensive haemorrhage may occur clouding the vitreous for long time or a retinal detachment may be present. In presence of fresh vitreous haemorrhage without retinal detachment, at first strict rest with head-up is advised. No oral medicine or drops has been found to be of use in helping the absorption of vitreous haemorrhage. If the haemorrhage does not show signs of absorption after 2-3 months or if retinal detachment is suspected, in such cases vitrectomy operation may be needed.

Vitrectomy  is a sophisticated microsurgical operation in which cloudy vitreous and scar tissue over retina are removed from the eye. Along with this, laser treatment can also be given at the same sitting by means of an instrument called ‘endolaser’. Being a complex surgical procedure with many potential complications, vitrectomy is reserved only for selected patients in whom all other treatment modalities have failed.

Conclusion :

With progress in the medical management of diabetes and the increasing life span of diabetics, it is inevitable that unless treated, most diabetics will suffer some degree of visual loss in decades after onset of the disease. Early detection of the retinopathy is the best protection against loss of vision. It should be remembered that laser treatment only helps in preventing further loss of vision, hence, it is most useful when used before the patient complains of decreased vision. Thus regular retinal check-up in diabetic patient is very important for early diagnosis and treatment to prevent blindness.

Recommended Schedule for Retinal Check-Up :

Age of  onset of Diabetes Mellitus Recommended time of First Examination Routine minimum  follow-up(more frequent in case of abnormal findings)
  0 – 30 years    5 years after onset     Yearly
  31 years and  above    At the time of diagnosis     Yearly
  Pregnancy with pre-      existing diabetic retinopathy   During first trimester     Every 3 months

Recommended by American Academy of Ophthalmology.