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Medical Retina

FAQ

It is the innermost layer of the eye responsible for vision.
It is the separation of retina from the other layers of eye.
Patients with family history of Retinal Detachment
  • Patients with high minus power (MYOPES)
  • Patients with presence of holes/tears in their Retina
  • Patients with advanced Diabetes Mellitus
  • Any injury to the eye
  • Preterm babies
  • Birth defects in the Retina
  • Following inflammation/infection of the eye
  • Tumours affecting the inner layer of the eye

Retina

What is retina and vitreous?

The eye functions like a camera the structures such as the cornea and lens focus the light on to the retina; the pupil acts like a camera diaphragm, regulating the amount of light that enters the eye.
The retina is the light sensitive tissue that lines the inner wall of the eye. The retina converts the visual image in to a signal that the brain can interpret. This signal is transmitted to the brain through the optic nerve. The retina is akin to the film in the camera. However expensive the camera may be, if the film is defective, one doesn't get good photos. Similarly if the retina is affected, we don't see well.
The central retina, called the "macula" is the most sensitive part. If we are able enjoy reading, recognize people we love, marvel at the intricate designs on a carving, it is because of the macula. If the macula is affected by disease we may lose some of these capabilities

Why retinal examination is important?

Retina is an extension of the brain. Much like the brain tissue, retina cannot regenerate diseases of the vitreous and retina can cause permanent blindness. Prompt and appropriate treatment can halt further damage and result in better outcome. Retinal examination allows early detection and treatment of retinal disorders.

What are the commonly advised investigations by a retinal specialist?

Retinal Angiogram (FFA & ICG)
Ultrasound scan (B-scan)
Optical coherence tomography (OCT)

What is FFA test?

FFA stands for fundus fluorescein angiography. This is a special test to evaluate the structure and health of the blood vessels within the retina by injecting a special dye in to a vein. This valuable test helps your doctor make the correct diagnosis and plan the best course of treatment. If you are diagnosed to have diabetic retinopathy, age-related macular degeneration or retinal blood vessel occlusion, you may be advised the test.

What is Ultrasonography (B scan)?

This is a painless test that makes use of sound waves to image the inside of the eye if the inside of the eye cannot be seen using routine clinical methods.

What is OCT?

OCT gives a cross-section view of the retina. Swelling of the retina, collection of fluid beneath the retina, anomalous blood vessels can be seen well with this test.

How does Diabetes affect the retina?

Diabetes affects the tiny blood vessels called capillaries of many organs, notably the retina, kidneys and nerve tissue. Diabetes affecting the retina is called Diabetic Retinopathy
The damaged capillaries in the retina leak blood, fluid, and proteins in to the retina resulting in retinal edema. When the edema involves the central retina (Macula), vision may be affected because of Macular Edema.
Further damage to retinal capillaries results in capillary closure and large part of the retina loses its blood supply and becomes ischemic. The ischemic retina manufactures new blood vessels in an attempt to revascularize itself. However, these new blood vessels are very friable and can rupture easily leading to bleeding within the eye.
When bleeding occurs, you will notice black spots swimming across your vision and if bleeding is large, you may lose vision. Over time, scar tissue proliferates within the eye, pulling the retina away from the underlying structures resulting in "Retinal Detachment". You may lose vision once this occurs.
Longer the duration of diabetes, more are the chances of vision being affected Macular edema (central retinal swelling), bleeding in to the cavity of the eye and retinal detachment can all result in vision loss in diabetics

What should a diabetic do to prevent damage to the retina?

Very good control of blood sugar
Keep blood pressure, cholesterol under control
Check for kidney disease and keep it under control
If you are anemic, take treatment for the same

Can Diabetes affect other parts of the eye?

Diabetes can also cause cataract, weakness of the optic nerve or eye muscles or increase in eye pressure. Cataracts occur at a younger age in diabetic patients. Damage to the small vessels of the optic nerve can affect vision, and weakness of the eye muscles may cause double vision.
A diabetic is also more likely to develop sudden loss of vision due to occlusion of the retinal vessels (branch or central retinal vein occlusion), bleeding in the vitreous cavity, detachment of the retina, or infections.

How is Diabetic Retinopathy treated?

Macular edema (swelling of the central retina) is usually treated with LASER therapy. Some forms of macular edema may be treated with special injections in to the eye. More than one session of LASER therapy may at times be necessary.
When the disease reaches the stage of new blood vessel growth, 3 to 4 sessions of LASER therapy spread out over a week or so may be necessary. If the disease does not come under control, additional sessions of LASER may be needed.
LASER can be performed only before bleeding occurs. Once bleeding has already occurred, LASER may be difficult or impossible.
Severe bleeding or retinal detachment will require microsurgery (vitreous surgery) to restore some vision.

What to expect during LASER therapy?

LASER is using a special form of light to destroy areas of abnormal retina.
Your pupils will be dilated first and then the eye will be anesthetized by applying anesthetic eye drops. You will be made to sit in front of the LASER machine and your eye specialist will place a small lens on your eye and direct the LASER light in to the eye. You will notice bright light flashes and most often no pain.
Alternately your doctor may deliver the LASER after making you sleep on a couch; in this technique no lens will be placed on your eye.
You will be requested to move your eye in different directions to enable the doctor to treat all the areas of the retina.
You can go home after the procedure and carry on with your normal activities. However, reading and performing near work may be difficult for a few hours because the pupils are dilated. There are no special dietary restrictions after LASER. You can wash your hair or face.
Rarely, if you are particularly light sensitive, your doctor may suggest an anesthetic injection so that you are more comfortable during the treatment.
You may be advised to sleep with head elevated and not to bend or lift heavy weights these are not precautions after LASER. These suggestions help prevent bleeding from the abnormal blood vessels.

Does LASER treatment restore vision?

LASER therapy for macular edema, mainly prevents additional vision loss but may also improve vision to some extent.
LASER for new blood vessel growth helps prevent complications such as bleeding inside the eye and retinal detachment.
LASER therapy will not make the blood go away it only decreases chances of further bleeding
Diabetes cannot be cured only controlled. Diabetic retinopathy may progress even after LASER or

What are the complications of laser treatment?

During the procedure, some people may find the light too bright, resulting in watering. Temporary vision loss lasting for a few minutes usually occurs immediately after the treatment. Blurred vision and inability to read may last until the effect of dilating medicines wane.
An assiduous person may notice decreased side-vision and also that it takes longer to see things when he or she enters a dark room. These side-effects cannot be prevented and are a small price to pay for avoiding blindness due to diabetic retinopathy.

What is Vitreous Surgery?

Vitreous surgery is microsurgery of the eye using 3 <1mm incisions. This surgery is used to treat complications of diabetic retinopathy such removal of bleeding inside the eye and repair of retinal detachment. Most patients get better with a single surgery while a few may need more than one surgery for visual improvement.

What is Retinopathy of Prematurity (ROP)?

As in other organs, the retina is also not completely developed in a premature baby. In a few premature babies, retinal blood vessels may develop abnormally causing bleeding and retinal detachment in the eye. This is called Retinopathy of Prematurity (ROP). Without prompt treatment, the baby may become blind or have poor vision for life.

Do all babies need a retinal examination for ROP?

While it is essential that babies born with a birth weight less than 1700 gm or earlier than 35 weeks of pregnancy are examined for ROP, it is better that all premature babies born before 37-38 weeks irrespective of weight are checked for ROP. This is particularly important if the baby has had other problems such as lack of oxygen, infection, blood transfusion or breathing trouble, etc after birth.

When should the baby be examined for ROP?

The retinal examination should be completed before "day-30" of the life of a premature baby. In babies with very low birth weight (<1200 gm birth weight), the examination should preferably be done earlier (at 2-3 weeks of birth).

What if baby has been diagnosed as having ROP?

Most often ROP does not need treatment, but you may have to visit the retinal specialist at periodic intervals to ensure that the retinal growth is satisfactory and ROP is regressing.
In few babies, ROP may progress and may need treatment. Treatment is most often with LASER delivered much the same way as the eye is examined. Each treatment session will take around half hour and the child is not subjected to general anesthesia. Rarely a freezing treatment (cryopexy) may be necessary. The treatment helps stop further growth of abnormal vessels and prevent vision loss.
If treatment is required, prompt treatment is essential.

Will baby have normal vision after LASER treatment

Most babies have reasonably good to normal vision, depending on the severity of the disease.

Will baby need surgery?

Rarely, ROP progresses despite the LASER or if LASER is not performed in time. In such children complicated surgery may be necessary to retain some vision or to give some vision. Children who need surgery usually have advanced disease and may not enjoy normal vision. Surgery for advanced ROP also has a higher chance of failure.

What is epiretinal membrane in the retina and what are its symptoms?

Membranes that form over the surface of the retina are called epiretinal membranes. They usually occur in patients over 50 years of age. The membrane when it lies over the central retina (macula), it can block the light; the membrane can also contract and distort the retina. This distortion will be of the retina causes visual disturbances what one sees will appear distorted or slanted. Double vision can also occur; things can appear small or large when compared with the other eye. The condition may progress slowly and a small number of patients may have poor vision.

What to expect after macular hole surgery? What are the complication rates?

You may have to maintain face down head positioning for 16-18 hours a day for a couple of weeks so that the gas we inject in to the eye is able to do its bit for closing the hole. If you have been having the hole for 2 years or lesser, there is 70-80% chance of hole closure after surgery. Vision may not be normal after surgery but improvement much as three lines of letters seen on the visual acuity testing chart can be expected.

What is CSCR?

In central serous chorio-retinopathy(CSCR), some fluid collects under the central retina (macula). Because of the fluid, you will see a relatively black patch wherever you wish to see and also distortion of images. Straight lines will appear bent and objects may appear smaller or larger than they are. Some vision loss also occurs.

What are the risk factors for developing this disease?

CSCR is typically a disease of young, adult males. Men, aged between 25 and 45 years represent about 85-90% of the patients. An anxious, emotionally stressed personality (Type A), use of steroids for various ailments (arthritis, asthma, skin allergies or organ transplant), pregnancy are risk factors for CSCR to occur.

What is the natural course of this disease?

Most often CSCR heals by itself in 3-4 months with normal to near normal vision. If the CSCR does not heal by this time period, treatment may be necessary. In people needing early restoration of vision for professional or personal needs, CSCR can be treated earlier.

What is the treatment of CSCR?

There is no medical treatment for CSCR. Before treatment, a FFA test should be done to identify the leaking point. An OCT test may also be necessary. Following these tests, laser treatment is done to seal the leak. It may take a 4-6 weeks for improvement in vision to occur.

Does this disease recur?

CSCR may recur in half to one-third of patients and 10% patients may have 3 or more recurrences. In most cases, the recurrences occur within a period of one year.

What is AMD?

Age-related Macular Degeneration (AMD) is a disease affecting the central sensitive part of the retina, called as themacula. The risk of acquiring this disease increases with advancing age. It has become a major cause of visual disability in older populations all over the world.

What are the types of AMD?

AMD can present either as a dry or wet form. Dry AMD is characterized by the presence of yellow deposits (accumulated debris from the aging retina), called drusen. With the passage of time these deposits enlarge and merge; the retina becomes atrophic (geographic atrophy) causing loss of vision.

What are the symptoms of AMD?

Dry AMD causes a gradual loss in central vision and in advanced cases, severe vision loss may also occur.
Patients with wet AMD may develop severe visual loss more often. In early stages of wet AMD, distortion and waviness of lines may be the early symptom. Reading small print will be difficult and one may notice that letters or words in a sentence go missing. Once bleeding occurs this is seen by the patient as a dark spot, which constantly obstructs central vision. Without treatment central vision may continue to worsen over time and patients may need assistance to carry out their daily routine activities.

How is AMD detected?

The best way of detecting AMD is getting a regular retinal examination done, especially, after the age of 50. An Amsler's test (a graph-paper like sheet) is very useful for detecting early changes in central vision. It can be done at home, by people having dry AMD, and at risk of developing wet AMD.
The retinal specialist will perform a complete eye examination and may order tests such as FFA, ICG angiograms andOCT. These tests will help select the ideal treatment for each patient.

What are the risk factors for AMD?

As the name suggests, the main risk factor is advancing age. The other risk factors are
Smoking
Hypertension
Obesity
Race (whites more than African Americans)
Gender (females more than males)

What are the treatment options for dry AMD?

No treatment is useful in advanced dry AMD (geographic atrophy). Treatment does have a role in reducing the risk of progression of the intermediate stages to the advanced stages (of dry or wet AMD). The Age Related Eye Diseases Study (AREDS) has recommended 500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene (equivalent to 25,000 International Units of vitamin A), 80 milligrams of zinc as zinc oxide, and 2 milligrams of copper as cupric oxide as dietary supplement in AMD. This formulation that is available in capsule form is neither a cure for AMD nor will it restore lost vision. It only delays the onset of advanced AMD.

What are the treatment options for wet AMD?

The treatment of wet AMD has evolved in the last 5-6 years from limiting degree of vision loss to maintaining and improving existing vision. Anti-VEGF (Vascular Endothelial Growth Factor) therapy and Photodynamic Therapy (PDT), or a combination of the two, form the basis of modern day treatment of wet AMD.
Before treatment, FFA test and OCT and in some patients ICG angiogram will be performed. This will help the eye specialist decide on the area of treatment, best treatment option and help in assessing the response to treatment.

Anti-VEGF therapy Anti-VEGF therapy works by blocking the action of VEGF, the molecule that promotes the growth of the abnormal blood vessel under the retina (CNVM). These drugs are injected directly inside the eye, to provide maximum concentration where it is needed that is near the CNVM.
Pegaptanib (Macugen) and Ranibizumab (Lucentis) are drugs that are FDA (US drug regulatory authority) approved for treatment. However another molecule, Bevacizumab that is essentially a drug approved for use in colorectal cancer patients is being used widely across the world by ophthalmologists to treat wet AMD. This is also an anti-VEGF agent with a cost advantage over the FDA approved drugs.
Bevacizumab is however not approved by the FDA for eye use National Eye Institute, a premier eye research organization in USA is funding a study evaluating the use of Bevacizumab in wet AMD patients. The results of this study, if favoring Bevacizumab, may give official recognition to this drug. Until then Bevacizumab use will remain "Off-Label".

What are the side-effects of these injections?

Some discomfort, rarely pain, redness of the eye may be present on the day of the injection and a day or two later.
These injections have to be repeated at monthly or 6 weekly intervals for a year or two and this means that the patient has to make repeated visits to the clinic and also undergo regular consultations and investigations.Combining these injections with other treatment such as Photodynamic Therapy (PDT) may however decrease the need for re-treatments and seem to be favored by most retinal specialists.
These injections are injected in to the eye this may very rarely be associated with a serious infection of the eye called endophthalmitis. If such a complication were to occur, the patient will need injection of antibiotics in to the eye or a surgery (vitrectomy) for controlling the infection. This will adversely affect the vision. This complication is however rare and may affect 1-2 out of 1000 patients.
These medicines are new developments and long-term side effects are not known at the moment. There is a possibility that these medicines may have some systemic side effects like increasing risk of stroke in people who are predisposed.

Is the injection painful?

The injections are given after applying anesthetic eye drops or anesthetic injection there may be slight discomfort and soreness on the day of injection, but not pain. To decrease the risk of serious infection after injection, you may have to use antibiotic eye drops for 2-3 days prior to and after the injection and the procedure will be performed under sterile precautions (like preparing for an operation). You will have to continue using the antibiotic eye drops after the injection and avoid washing your hair for 3 days. You need to avoid water entering the eye for 3 days as well. The symptoms you need to be wary of are
Decreased vision
Pain
Increasing redness
Discharge from the eye
Swelling of the lids
If you notice any of these symptoms you need to consult your doctor immediately.