What is the retina?
Retina is the neural layer at the back of the eye that
transforms luminous energy of the image received by the eye to neural energy
transmitted ahead to the brain. In terms of a very common comparison, the eye
being the camera the retina is the film. However, the film gets exposed to
light and the image is recorded on it… the retina is a dynamic structure that
needs nourishment and consumes energy.
What is Retinal Detachment?
Movement of retina from its usual location is called retinal detachment. It usually signifies the separation of the pigment layer from the sensory layer. This cuts the retina off from its blood supply and nutrition. The retina will degenerate and lose its ability to function if it stays detached long enough.
What is a retinal tear?
The retina may tear at certain points due to pull by the vitreous gel. A child’s vitreous has the consistency of egg white… and is firmly attached to the retina at certain points. Usually with changes in hydration of the vitreous, it separates from the underlying retina. This separation usually is trouble and symptom free… but may cause ters in the retina at times. This allows fluid to seep under and elevates the retina from the choroid ( The pigment and vessel layer that nourishes the retina)
What are the zones of the retina and how are they important?
The most sensitive area of the retina is the Macula. This is primarily composed of cones and is responsible for the fine visual work we put our eyes to – reding, recognizing faces etc. The peripheral retina is primarily composed of rods.
What are the types of retinal detachment?
There are three major types of retinal detachment:
- Rhegmatogenous (Break)
A break in the sensory layer can cause the fluid to seep in and lifts the retina off. This is more commonly seen in eyes weakened by HIGH MYOPIA, EYE INJURY or PREVIOUS EYE SURGERY
- Traction
This is the kind of detachment that develops when strands of vitreous or scar tissue pull on the retina as happens in DM
- Exudative
This kind of detachment results
when any inflammatory disease of the eye results in collection of fluid under
the retina due to swelling or bleeding
Each of
these would need a different approach and comprehensive care facility to treat
the patient as a whole and not an isolated episode of sight threat.
How can you tell if you could be having a retinal detachment?
There is usually quite a typical presentation of an RD:
- Flashes of light
- Wavy or watery vision
- Sudden decrease of vision
- ‘shower of floaters’
- curtain covering the vision and obstructing it
Who is at risk for Retinal detachment?
- High myopes
(More than -6 correction) LASIK surgery to
correct the ‘number’ may rid one of glasses but it does so by altering the
shape and /or thickness of the cornea. IT DOES NOT ALTER THE RISK OF
RETINAL DETACHMENT in a ‘corrected’ eye. Even myopes
who have had refractive surgery MUST visit an ophthalmologist for a
quarterly eye exam to track the retina. Near sighted subjects have
a 1 in 20 chance of a RD as compared to 1 in 10,000 in the normal population.
- Ocular Trauma This, too
places the eye at high risk for a detachment by traction
or bleeding or direct trauma?
- RD in contralateral
eye This signifies a weak retina.
- Previous eye surgery This
may be as routine as cataract surgery!
What can you do?
- Retinal detachment is an OCULAR EMERGENCY. It is critical to report early.
- PERIODIC EYE EXAM by an OPHTHALMOLOGIST is likely to pick up early or predisposing changes in the retina. The preventive steps can then be taken and retinal detachment can be averted.
- When at risk avoid jerky activities like running/ weight lifting.
- Better and timely treatment of seasonal allergies… the force generated by a sneeze at the nostrils is 600N/meter square
What you may have to do…
PREVENTION IS THE BEST CURE.
Unless you undergo timely and
appropriate treatment including surgery by an expert, you may suffer
irreversible visual impairment.
This will affect your ability to perform normal daily chores that you may be quite used to before the visual disaster:
- Driving: Join car pools or explore possibility of public transport.
-
- Home safety : Ensure that your home has no rugs that you could trip over and is brightly lit without and shade or shadow.
- Enlist help : Do inform your friends and relatives seek help in any activity that you may find difficult to perform
What are the tests you may have to undergo?
- Direct and indirect ophthalmoscopy
- Vision and refraction
- Colour vision
- Slit lamp examination
- Intraocular pressure measurement
- Ultrasonography of the eye
- Retinal photography
- Fluoresceine angiography
What are the treatment options available?
All rhegmatogenous retinal detachments need immediate specialist consult atleast. All fresh RDs MUST be treated surgically within 24-48 hours. All chronic and longstanding RDs must be addressed within a week of diagnosis.
Exudative Rds usually resolve spontaneously with appropriate menegement of the underlying condition.
Traction RDs require pars plana vitrectomy and silicone oil tamponade.
Small tears or breaks may be managed by LASER photocoagulation or cryopexy.
True RDs require surgical intervention. This may be in the form of
- Scleral buckle
- Pneumatic retinopexy
- Intraocular silicone oil tamponade
Scleral Buckle
The retinal tear is first repaired with cryopexy, the fluid drained out and thereafter, a soft sponge or hard silicone band is used to indent the sclera at the point of detachment or circumferentially in case of major RDs. This is sutured to reestablish adhesion between RPE and the sensory retina and needs general anaesthesia.
Pneumatic retinopexy
A gas bubble is introduced intravitreally- usually perfluoropropane( C3F8) under local anaesthesia. Since gas rises, this is best suited for superior detachments. Careful eye and head positioning are of utmost importance for a good “take”.
Silicone oil tamponade
This is similar to pneumatic retinopexy escept that the tamponade material is the silicone oil.
What can you expect after the surgery?
- Strict head and eye positioning will be required in the immediate postoperative period and is critical for the result.
- The “curtain” that got you to the doctor in the first place may not immediately disappear. As the retina regains its perfusion and heals, the curtain gradually fades and the vision may clear significantly depending upon the severity and the type of RD and the timely intervention.
- Time of surgical intervention is of critical importance and cannot be overemphasized. The nature of all RDs is to progress to become total within 6 months if left untreated.
- Unfortunately, all retinas may not reattach. If such is the case, the eye is likely to continue to deteriorate and ultimately become blind.
Author - Dr. Sanjay Dhawan
Last Update - 09 August, 2007
New Delhi, India
