RETINA

The eye is like a camera with a lens in front and a film/light-sensitive tissue (retina) at the back. The retina converts the ocular image into a signal that is sent to the brain. The central part of the retina called the macula, is used for straight-ahead vision and what is in your direct line of sight. A damaged retina can lead to significant visual disturbances and if not treated in time, can lead to permanent vison loss.

A healthy macula is crucial for tasks involving fine vision such as reading, recognizing faces and distinguishing things. The area surrounding the macula helps in mobility and in seeing from the ‘corner’ of the eye. The retina is connected to the brain by the optic nerve. In front of the retina is the vitreous cavity, which is filled with a gel-like substance, called the vitreous.

INVESTIGATIONS IN RETINAL DISEASES

1. FUNDUS FLUORESCEIN ANGIOGRAPHY

A self-explanatory consent form, which explains the side effects in detail, is provided to the patients. Consent is required before the procedure. Patients can have a light meal before undergoing the procedure and must be accompanied by a family member.

Eye drops are administered to enlarge the pupils — this takes approximately 30-40 minutes. Patient is then be asked to sit still in front of the camera while a series of color photographs of eyes are taken. An injection (contrast) is then injected and more photographs are taken.
The test takes approximately 10-15 minutes.
It is a very safe procedure and serious side effects are uncommon. However, there is a rare possibility that a patient may have a reaction to the contrast. Some patients may experience slight nausea after the dye injection, but the feeling usually passes quickly.

Patients who are allergic to the dye can develop itching and a skin rash. These symptoms generally respond quickly to medications such as anti-allergics or steroids.

There is also a possibility of the dye going into the skin at the injection site, this may cause some discomfort or discoloring of the skin for several days. The fluorescein dye turns the patient’s urine orange and may slightly discolor the skin as well for a brief period.

2. ULTRASONOGRAPHY OF POSTERIOR SEGMENT

A thick jelly is placed on the ultrasound probe, which is then gently placed on the eye over the lid. It is a safe and painless procedure, no X-ray exposure occurs in this test. Your doctor uses these echo pictures to arrive at a diagnosis, the probable future health of your eye, and a treatment plan. However, the test only reveals the structure of the inside of the eye.

3. OPTICAL COHERENCE TOMOGRAPHY (OCT)

Optical coherence tomography is a non-invasive imaging test, which uses light waves to take cross-section pictures of patients’ retina.
With OCT, the ophthalmologist can see each of the retina’s distinctive layers. This allows mapping and measuring retinal thickness. These measurements help with diagnosis. OCT also guides treatment for retinal diseases, like age-related macular degeneration (AMD) , diabetic eye disease, macular edema.
The ophthalmologist may or may not put dilating eye drops . These drops widen the pupil and make it easier to examine the retina.
Patient sits in front of the OCT machine and rests head and chin on a support to keep them motionless. The equipment then scans the eye without touching it. Scanning takes about 5 to 10 minutes.
OCT is often used to evaluate disorders of the optic nerve as well. The OCT exam helps the ophthalmologist see changes to the fibers of the optic nerve. For example, it can detect changes caused by glaucoma.
OCT relies on light waves. It cannot be used with conditions that interfere with light passing through the eye. These conditions include dense cataracts or significant bleeding in the vitreous.

4. OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY (OCTA)

This test takes pictures of the blood vessels in and under the retina. OCTA is like fluorescein angiography, but is a much quicker test and does not use a dye (dyeless angiography). It can be safely done in patients allergic to fluorescein dye, and with renal disease (where dye/ contrast is contraindicated)

OCT and OCTA help diagnose many eye conditions, including:
macular hole
macular pucker
macular edema
age-related macular degeneration
central serous retinopathy
diabetic macular edema
abnormal blood vessels within/ underneath the retina
blood vessel blockage

RETINAL PROCEDURES

1. INTRAVITREAL INJECTIONS

a) Anti-VEGF treatment
Anti-VEGF (anti- Vascular Endothelial Growth Factor) injections are a group of medicines which reduce new blood vessel growth or oedema (swelling). They can be used to treat a number of eye conditions which cause new blood vessel growth or swelling under the macula area of the retina.
Currently anti-VEGF treatment is used for:
• ‘wet’ Age-related macular degeneration (AMD)
• Diabetic maculopathy
• Macular oedema caused by retinal vein occlusion.
• Myopic Choroidal Neovascularisation.
• Retinopathy of Prematurity. (ROP)
New blood vessel growth and macular oedema can also occur in other retinal conditions, so in the future anti-VEGF medications may be used in a wider range of situations.
Anti-VEGF treatments are given by an injection into the white portion of the eye and work by reducing the growth of new blood vessels and the oedema (swelling). Doing this can reduce the risk of scarring and damage to the retina caused by these new vessels, which in turn can help to avoid further sight loss and for some people cause an improvement in vision.
Depending on the condition of the patient, the ophthalmologist performs tests to decide whether treatment with antiVEGFs is required .
After examining the eye, the doctor may undertake further tests to have a clearer picture of the patient’s eye and symptoms.

Procedure
Anti-VEGF drugs are given as an injection into the vitreous (the jelly-like substance inside the eye). The injection is given through the white of the eye (the sclera). The injection needs to be given in a sterile way in an operating theatre.
The needle used for the injection is small and short and the injection itself only takes a few seconds. The patients have had an anaesthetic drop in their eye, before the procedure, so the injection feels like a small point of pressure on the eye.
After the injection, vision may be blurry for several hours because of the dilating eye drops; this should improve by the next day or the day after. The white of the eye may get red after the injection for a few days. Black swirls in the vision may be noticed for a few weeks (this is the drug floating in the vitreous gel). The eye usually feels comfortable by the next day. Some eye drops are given for a few days after the injection to prevent an infection.
The different AntiVEGFs available are
1. ACCENTRIX (RANIBIZUMAB)
2. EYLEA (AFLIBERCEPT)
3. PAGENAX (BROLUCIZUMAB)
4. AVASTIN (Bevacizumab, off label use)
5. RAZUMAB, RANIEYES, OCEVA ( RANIBIZUMAB BIOSIMILARS)

b) Steroids

Intravitreal steroids are used in some eyes with diabetic retinopathy, retinal vein occlusion and uveitis. Steroids help to reduce fluid leakage associated with these disorders.
The commonly used steroid is Dexamethasone Implant (Ozurdex), which is injected in the vitreous cavity just like any anti-VEGF drug.

c) Antibiotics

Antibiotic, anti fungal and antiviral drugs are injected in the vitreous cavity to treat patients with infections in the eye such as endophthalmitis and retinitis.

DIABETIC RETINOPATHY

Diabetic retinopathy is a complication that affects eyes, and can develop in anyone who has type 1 or type 2 diabetes It’s caused by damage to the blood vessels of the retina.
In its early stages, diabetic retinopathy usually causes no symptoms. As the disease progresses, one might develop
• Spots or dark strings floating in the vision (floaters)
• Blurred vision
• Fluctuating vision
• Dark or empty areas in the vision
• Vision loss
In later stages, it can even lead to blindness. Thus regular dilated retina evaluations in diabetic patients can pick up the disease in its early stages and prevent severe vision loss.
The longer one has diabetes and the less controlled one’s blood sugar is, the more likely is he/she to develop diabetic retinopathy.

Risk factors
Anyone who has diabetes can develop diabetic retinopathy. The risk of developing the eye condition can increase as a result of:
• Having diabetes for a long time
• Poor control of blood sugar level
• High blood pressure
• High cholesterol
• Pregnancy
• Tobacco use
• Anaemia, compromised renal status

There are two types of diabetic retinopathy:

• Early diabetic retinopathy. In this more common form — called nonproliferative diabetic retinopathy (NPDR) — new blood vessels aren’t growing (proliferating).
In nonproliferative diabetic retinopathy (NPDR), the walls of the blood vessels in the retina weaken causing leakage of fluid and blood into the retina.
NPDR can progress from mild to severe as more blood vessels become blocked.
Sometimes retinal blood vessel damage leads to a buildup of fluid (edema) in the center portion (macula) of the retina. If macular edema decreases vision, treatment in the form of intravitreal injections/ laser is required to prevent permanent vision loss.

• Advanced diabetic retinopathy. Diabetic retinopathy can progress to this more severe type, known as proliferative diabetic retinopathy (PDR). In this type, damaged blood vessels close off, causing the growth of new, abnormal blood vessels in the retina. These new blood vessels are fragile and can leak into the clear, jellylike substance that fills the center of the eye (vitreous). (Vitreous Haemorrhage)

PROLIFERATIVE DIABETIC RETINOPATHY (PDR)

PDR WITH VITREOUS HAEMORRHAGE

Eventually, scar tissue from the growth of new blood vessels can cause the retina to detach from the back of the eye. (Tractional Retinal Detachment)

PDR WITH TRACTIONAL RETINAL DETACHMENT

If the new blood vessels interfere with the normal flow of fluid out of the eye, pressure can build in the eyeball. This build up can damage the nerve that carries images from eye to the brain (optic nerve), resulting in glaucoma. (Neovascular Glaucoma)

Prevention
Regular eye exams, good control of blood sugar and blood pressure, and early intervention for vision problems can help prevent severe vision loss.
• Regular monitoring and good control of blood sugar level.
• Ask your doctor about a glycosylated hemoglobin test. The glycosylated hemoglobin test, or hemoglobin A1C test, reflects average blood sugar level for the two- to three-month period before the test. For most people with diabetes, the A1C goal is to be under 7%.
• Keeping blood pressure and cholesterol under control.
• Avoid smoking/ or use of other types of tobacco
• Pay attention to vision changes

TREATMENT

1. Injections : anti-VEGFs/ steroid :

These medications when injected in the back of the eye, help reduce swelling of the macula, slowing vision loss and perhaps improving vision. Multiple such injections are needed depending on the severity of one’s Diabetic Retinopathy and control.

2. Laser Treatment
Laser is used to help seal off leaking blood vessels (FOCAL LASER). This can reduce swelling of the retina.
Laser can also help shrink blood vessels (PANRETINAL PHOTOCOAGULATION/ PRP LASER) and prevent them from growing again. This is done in multiple sittings. Sometimes more than one treatment is needed.

LASERED DIABETIC RETINA (AFTER PRP LASER)

3. Vitrectomy
With advanced PDR, (Vitreous Haemorrhage or Tractional Retinal Detachment), surgery called vitrectomy (Pars Plana Vitrectomy/ MicroIncision Vitrectomy Surgery) is needed.

DIABETIC RETINOPATHY

NORMAL RETINA

EYE WITH DIABETIC RETINOPATHY

PROLIFERATIVE DIABETIC RETINOPATHY (PDR)

PDR WITH VITREOUS HAEMORRHAGE

PDR WITH TRACTIONAL RETINAL DETACHMENT

LASERED DIABETIC RETINA (AFTER PRP LASER)

AGE RELATED MACULAR DEGENERATION (AMD)

Age-related macular degeneration (AMD) is a problem where a part of the retina called the macula is damaged., due to ageing.

AMD is very common and is a leading cause of vision loss in people 50 years or older.
With AMD there is loss of central vision, fine details, near vision, with sparing of peripheral (side) vision.

Two Types of AMD

1.Dry AMD
This form is quite common. About 80% (8 out of 10) of people who have AMD have the dry form. Dry AMD is when parts of the macula get thinner with age and tiny clumps of protein called drusen grow. There is slow loss of central vision. There is no way to treat dry AMD yet.

DRY AGE RELATED MACULAR DEGENERATION (DRUSENS)

DRY AGE RELATED MACULAR DEGENERATION (GEOGRAPHIC ATROPHY)

2.Wet AMD
This form is less common but much more serious. Wet AMD is when new, abnormal blood vessels grow under the retina. These vessels may leak blood or other fluids, causing scarring of the macula. There is faster central vision loss with wet AMD than with dry AMD.
Many people don’t realize they have AMD until their vision is very blurry. This is why it is important to have regular visits to an ophthalmologist, who can look for early signs of AMD before any vision loss happens.

WET AGE RELATED MACULAR DEGENERATION

Age-Related Macular Degeneration Treatment

Dry AMD Treatment
Right now, there is no way to treat the dry form of AMD. However, people with lots of drusen or serious vision loss might benefit from taking a certain combination of nutritional supplements.

Wet AMD Treatment
To help treat wet AMD, there are medications called anti-VEGF drugs. Anti-VEGF treatment helps reduce the number of abnormal blood vessels in the retina and slows any leaking from blood vessels.

MACULAR HOLE

It is a full thickness defect in the macula ( vision forming portion of retina)
The most common symptom of macular hole is a gradual decline in the central (straight-ahead) vision of the affected eye.This can occur as:
Blurring
Distortion (straight lines appearing wavy)
A dark spot in the central vision

The degree to which vision is affected depends on the size of the macular hole, as well as the stage of its development.
Macular hole commonly affects people over the age of 55 and most often occurs in women. The vast majority of cases develop spontaneously without an obvious cause. For this reason, there is currently no effective way to prevent its formation and development. If a macular hole develops in one eye, there is a 5% to 15% risk of one developing in the other eye.

Diagnostic Testing

Clinical examination followed by Optical Coherence Tomography

OCT IN FULL THICKNESS MACULAR HOLE

Optical coherence tomography (OCT) is the current gold standard in the diagnosis, staging, and management of macular holes.

Treatment and prognosis

The treatment for a full thickness macular hole is surgical, which is Vitrectomy surgery, in which the vitreous gel is removed to stop it from pulling on the retina, following which a gas bubble is placed in the eye to gently hold the edges of the macular hole closed until it heals.
The patient is asked to maintain a face-down position up to 2 weeks, depending on the characteristics of the macular hole.

Vitrectomy has a success rate of over 90%, with patients regaining some or most of their lost vision, with potential complications being cataract formation, retinal detachment, infection, glaucoma, bleeding, and re-opening or persistence of the macular hole (less than 10% of cases)

OCT of a patient before and after Vitrectomy surgery of a Macular Hole

RETINAL LASER PHOTOCOAGULATION

It is an OPD procedure used to treat a number of retinal conditions, including
retinal holes or tears, (Barrage Laser)- to seal a retinal tear to prevent development of a retinal detachment, a potentially blinding condition.
proliferative diabetic retinopathy, (Pan Retinal Photocoagulation / PRP Laser) – to seal or destroy leaking blood vessels to prevent further retinal damage and preserve vision
macular edema (Focal Laser)
retinal vein occlusion. (Sectoral PRP Laser)
and Central Serous ChorioRetinopathy (Focal Laser)

The laser procedure works by creating small areas of scar tissue that can seal off a tear or leaking blood vessels. It can also slow the growth of abnormal blood vessels (neovascularization) in the eye.

The procedure cannot typically restore vision that is already lost, but it can reduce the risk of future vision loss.

Barrage laser to a RETINAL HOLE

BARRAGE LASER TO A RETINAL TEAR

BARRAGE LASER TO RETINAL BREAK

PAN RETINAL PHOTOCOAGULATION/PRP LASER

MACULAR DEGENERATION

DRY AGE RELATED MACULAR DEGENERATION (DRUSENS)

DRY AGE RELATED MACULAR DEGENERATION (GEOGRAPHIC ATROPHY)

WET AGE RELATED MACULAR DEGENERATION

RETINAL DETACHMENT

What Is a Detached Retina?
A detached retina is when the retina lifts away from the back of the eye. The retina does not work when it is detached, making vision blurry. A detached retina is a serious problem, and needs a surgery to fix it.
How Does the Retina Detach?
With ageing, the vitreous in the eyes starts to shrink and get thinner. As the eye moves, the vitreous moves around on the retina without causing problems. But sometimes, as the vitreous shrinks, it may pull hard enough to cause a tear in the retina. When that happens, fluid can pass backwards through the tear and lift (detach) the retina.

RETINAL HOLE

RETINAL TEAR

RHEGMATOGENOUS RETINAL DETACHMENT (RRD)

Who Is at Risk for a Retinal Detachment?
One is more likely to have a detached retina if he/she
• needs glasses to see far away (nearsightedness or myopia)
• has had cataract, glaucoma, or other eye surgery
• takes glaucoma medications that make the pupil small (like pilocarpine)
• had a serious eye injury(trauma)
• had a retinal tear or detachment in the other eye
• has family members who have had retinal detachment
• have weak areas in the retina (seen by a retina specialist during a dilated retinal exam)
Early Signs of a Detached Retina
• Seeing flashing lights all of a sudden, perceived as sparkling lights in dim light
• Noticing many new floaters at once. These can look like specks, lines or cobwebs in the field of vision.
• A shadow appearing in the peripheral (side) vision.
• A gray curtain covering part of field of vision.

Floaters

Peripheral field loss

How Is a Detached Retina Diagnosed?
The ophthalmologist will put drops in the eyes to dilate (widen) the pupil and will look through a special lens and a head mounted instrument to check the retina. Sometimes an Ultrasound of the back of the eye may be needed to diagnose the detachment.

ULTRASOUND OF RETINAL DETACHMENT

How Is a Detached Retina Treated?
Surgery is done to repair a detached retina. Kindly refer to the Retinal Surgery Section.

RETINAL LASER PHOTOCOAGULATION

It is an OPD procedure used to treat a number of retinal conditions, including
retinal holes or tears, (Barrage Laser)- to seal a retinal tear to prevent the development of a retinal detachment, a potentially blinding condition.
proliferative diabetic retinopathy, (Pan Retinal Photocoagulation / PRP Laser) – to seal or destroy leaking blood vessels to prevent further retinal damage and preserve vision
macular edema (Focal Laser)
retinal vein occlusion. (Sectoral PRP Laser)
and Central Serous ChorioRetinopathy (Focal Laser)

The procedure cannot typically restore vision that is already lost, but it can reduce the risk of future vision loss.

Barrage laser to a RETINAL HOLE

BARRAGE LASER TO A RETINAL TEAR

BARRAGE LASER TO RETINAL BREAK

PAN RETINAL PHOTOCOAGULATION/PRP LASER

RETINOPATHY OF PREMATURITY

Vitreo Retinal Surgery

As the name implies, this delicate surgery takes place where the gel-like vitreous and light-sensitive layer inside the eye (retina) are found.
Common Indications for Vitrectomy
• Diabetic vitreous hemorrhage.
• Retinal detachment – Rhegmatogenous (secondary to a retinal break) or Tractional
• Epiretinal membrane.
• Macular hole.
• Proliferative vitreoretinopathy.
• Endophthalmitis.
• Intraocular foreign body removal.
• Retrieval of lens nucleus following complicated cataract surgery.
• Retrieval of a dropped Intraocular Lens.

VARIOUS TREATMENT OPTIONS
Retinal holes or breaks are treated with laser photocoagulation (form of heat therapy) or cryopexy (a freeze treatment) as an outpatient procedure. During laser treatment, dot like burns are placed around the break to “weld/ seal” the break. In Cryopexy the area around the break is frozen and it helps seal the break.

Retinal Detachments are treated with surgery viz scleral buckling and complex vitreoretinal surgery (MicroIncision Vitrectomy) involving use of Silicone oil or gases.

In scleral bucking, a silicon band, is anchored with stitches around the eyeball to gently push the wall of the eye against the detached retina.

In vitrectomy, three tiny incisions are made in the white of the eye to create openings for the various instruments that are inserted inside the eye, that do not usually require placement of stitches afterwards (i.e. micro incision sutureless surgery). The instruments that pass through these incisions include:
• Light pipe, which serves as a microscopic, high-intensity flashlight for use within the eye.
• Infusion port, used to replace fluid in the eye with a saline solution and to maintain proper eye pressure.
• Vitrector, or cutting device, that removes the eye’s vitreous gel in a slow, controlled fashion. It protects the delicate retina by reducing traction/ pull while the vitreous gel is removed.
Once the vitreous gel is removed, it is replaced with silicone oil/ gas to keep the retina in place.

What To Expect?
Bleeding, infection, progression of cataract and retinal detachment are potential problems after any retinal surgery, but these complications are relatively unusual.
With modern vitreoretinal instrumentation, around 90 percent of cases with a retinal detachment can be successfully treated, Visual results are good if the retinal detachment is repaired before the macula (the centre region of the retina responsible for fine, detailed vision) detaches. Thus, it is important to contact your retina surgeon in time when you notice any flashes or floaters or a curtain in field of vision.

Surgery is generally performed under local anesthesia (i.e. patient is awake but the eye is anesthetized via local retrobulbar/ peribulbar lidocaine/marcaine). This allows for the fastest and safest surgery with essentially no risk systematically. Depending on the type of condition, the surgery can last anywhere between 30-90 minutes. Once the surgery is completed, the patient’s eye is patched until their post op visit which is usually within 24 hours following surgery. At the first postoperative visit, the patch is removed and instructions including use of eye drops is given. Following surgery, often special positioning (e.g. face down) is required in order for the retinal condition to be managed.
Vision following surgery is hindered upto 6 weeks if gas is utilized. There is typically very minor discomfort following surgery lasting 24-48 hours. It is extremely rare to have severe pain following surgery; if that happens or there is any vision loss, patients are advised to contact the doctor immediately.
If Silicone oil is injected, the patient requires a second surgery for its removal from the eye.

• Diabetic vitreous hemorrhage.