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RETINA CLINIC
Facts
Light rays enter the eye
through the transparent cornea at the front of the eye, then pass through the
pupil in the centre of the iris. The light then passes through the lens and
vitreous (a jelly-like substance) before reaching the retina.
The retina is the light
sensitive tissue layer at the back of the eye. The cones and rods of the retina
send messages about what is seen along the optic nerve to the brain, where these
messages are interpreted into the pictures we see.
In Eye Specialty Hospital we
have an experienced specialists in retinal pathologies ,we are proud that we
have the facilities and the qualifications and the most up to date techniques in
dealing with retinal pathologies.
Common retinal pathologies
- Diabetic retinopathy
- Macular degeneration
- Retinal detachment
- Other common retinal pathologies
Diabetic retinopathy
This common complication of diabetes is the
leading cause of vision loss. Especially likely when diabetes is poorly
controlled, diabetic retinopathy can occur as background or nonproliferative
retinopathy or as proliferative retinopathy.
Background or nonproliferative retinopathy can
cause swelling of the retina (macular edema) and mild to moderate blurring of
vision. Dietary or insulin treatment does not necessarily stop progression. With
time, the retinal disease can progress to the proliferative form.
In proliferative retinopathy, tiny blood
vessels grow into the vitreous - the jellylike fluid that fills the interior of
the eyeball behind the lens. If these vessels break and bleed into the vitreous,
severe vision loss may result.
Non-Proliferative Diabetic Retinopathy
PDR carries the greatest risk of loss of vision
and typically develops in eyes with advanced NPDR. PDR occurs when blood vessels
on the retina or optic nerve become blocked consequently starving the retina of
necessary nutrients. In response, the retina grows more blood vessels (neovascularization).
Unfortunately these new vessels are abnormal and cannot replenish the retina
with normal blood flow.
PDR may lead to any one of the following:
Vitreous hemorrhage - proliferating retinal
blood vessels grow into the vitreous cavity and break down. Both the
hemorrhaging and resultant scar tissue may interfere with vision.
Traditional retinal detachment - scar tissue in the vitreous and on the retina
cause the retina to detach.
Tractional and rhegmatogenous retinal detachment - scar tissue creates a hole or
tear in the retina causing it to detach.
Neovascular glaucoma - abnormal blood vessel growth on the iris blocks the flow
of fluid out of the eye causing the pressure to increase and damaging the optic
nerve.
What are the symptoms of diabetic retinopathy?
Generally, people with mild NPDR do not have
any visual loss. A dilated eye exam is the only way to detect changes inside the
eye before loss of vision begins. People with diabetes should have an eye
examination at least once a year. More frequent exams may be necessary after
diabetic retinopathy is diagnosed.
People with PDR experience a broader range of symptoms. They may:
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see dark floaters
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experience loss of central or peripheral vision
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experience visual distortions or blurriness
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experience temporary or permanent vision loss
Glaucoma may also become a problem. A person with diabetes is nearly twice as
likely to get glaucoma as other adults. And, as with diabetic retinopathy, the
longer you have had diabetes, the greater your risk of getting glaucoma.
Glaucoma may be treated with medications, laser, or other forms of surgery.
Diagnosis of diabetic retinopathy
Diabetic retinopathy is diagnosed by dilating
the pupil and looking inside the eye with an ophthalmoscope. If an
ophthalmologist discovers diabetic retinopathy, he or she may wish to order
color photographs of the retina through a test called fluorescein angiography.
During this test, a dye is injected into the arm and quickly travels throughout
the blood system. Once the dye reaches the blood vessels of the retina, a
photograph is taken of the eye. The dye allows the ophthalmologist to detect
damaged blood vessels that are leaking dye.
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3D OCT
Introduction
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Optical Coherence Tomography (OCT) is a new noninvasive medical diagnostic imaging technology which can perform micron resolution cross-sectional or tomographic imaging
in biological tissues.
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The operation of OCT is analogous to ultrasound B-mode imaging except that light
is used rather than acoustic.
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3D-OCT can get high-quality, high-resolution scans that can be assembled into a
3D image. This gives the physician the ability to evaluate each B-scan or to look at the whole retina by looking at the 3D image.
OCT Physics
3D OCT
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The newest OCT device (Topcon 3DOCT-1000) can take multiple b-scan in a linear fashion
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And it takes 128 b-scan in 3.6 sec for 6*6 mm zone of the retina
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So it can give us a 3D structure with full pin-point registration for each A-scan
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And the computer can also analyze the images and showing us the thickness map for the 6*6 mm zone and compare it with a normative database
OCT Anatomy
OCT for Ocular Diseases
OCT has been shown to be clinically useful for imaging and directly visualizing selected ocular diseases including: macular holes, ERM, Retinal Vascular Occlusion, macular edema, CSR, ARMD, schisis cavities associated with optic disc pits, retinal inflammatory diseases.
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Treatment of diabetic retinopathy
We may suggest laser surgery in which a strong light beam is aimed onto the
retina. Laser surgery and appropriate follow-up care can reduce the risk of
blindness by 90 percent. However, laser surgery often cannot restore vision that
has already been lost. That is why finding diabetic retinopathy early is the
best way to prevent vision loss.
Types of laser used to treat diabetic retinopathy
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Argon laser photocoagulation technique.
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Photodynamic therapy (PDT) technique for macular involvement.
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Other treatment modalities.
The most effective overall strategy for diabetic retinopathy is to prevent it as
much as possible. Strict control of blood sugar levels will significantly reduce
the long-term loss of vision from retinopathy. With improved diagnosis and
treatment, only a small percentage of people with retinopathy develop serious
vision problems
Intravitreal steroid injection
Because the earliest stages of diabetic
retinopathy include inflammation, intraocular corticosteroids have been utilized
with some success in selected patients. This form of treatment includes the use
of a long-acting corticosteroid (triamcinolone acetonide) injected into the
vitreous cavity by way of a very tiny needle under topical (drops) anesthesia.
This treatment may reduce retinal swelling and improve visual acuity in patients
with diabetic macular edema. However, visual recovery may be limited and the
effect may last only 3 to 6 months after the treatment. Other clinical trials on
corticosteroids include a sustained-release drug delivery device surgically
implanted inside the eye to allow constant release of the medication.
Information
for People With Diabetes
Diabetes is a very serious disease that can cause problems like blindness, heart
disease, kidney failure, and amputations. But by taking good care of yourself
through diet, exercise, and special medications, you can control diabetes. And
there is more good news. Diabetic eye disease, a complication of diabetes, can
be treated before vision loss occurs.
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