All About Retinal detachment

Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency. [1]

The retina is a thin disc-shaped layer of light-sensitive tissue on the back wall of the eye. Its job is to translate what we see into neural impulses and send them to the brain via the optic nerve. Occasionally, injury or trauma to the eye or head may cause a small tear in the retina, which allows fluid to seep through, and peel it away like a bubble in wallpaper.

Types

* Rhegmatogenous retinal detachment - A rhegmatogenous retinal detachment occurs due to a hole, tear, or break in the retina that allows fluid to pass into the subretinal space between the sensory retina and the retinal pigment epithelium.
* Exudative, serous, or secondary retinal detachment - An exudative retinal detachment occurs due to inflammation, injury or vascular abnormalities that results in fluid accumulating underneath the retina without the presence of a hole, tear, or break.
* Tractional retinal detachment - A tractional retinal detachment occurs when fibrovascular tissue, caused by an injury, inflammation or neovascularization, pulls the sensory retina from the retinal pigment epithelium.

Prevalence

The risk of retinal detachment in otherwise normal eyes is around 5 in 100,000 per year.[2] Detachment is more frequent in the middle-aged or elderly population with rates of around 20 in 100,000 per year [1]. The lifetime risk in normal eyes is about 1 in 300 [2].

* Retinal detachment is more common in those with severe or extreme myopia (above 5-6 diopters), as their eyes are longer and the retina is stretched thin. The lifetime risk increases to 1 in 20 [3]. Myopia is associated with 67% of retinal detachment cases. Patients suffering from a detachment related to myopia tend to be younger than non-myopic detachment patients.

* Retinal detachment can occur more frequently after surgery for cataracts. The estimate of risk of retinal detachment after cataract surgery is 5 to 16 per 1000 cataract operations.[4]. The risk may be much higher in those who are highly myopic, with a frequency of 7% reported in one study [5]. Young age at cataract removal further increased risk in this study.

* Tractional retinal detachments can also occur in patients with proliferative diabetic retinopathy [6]or those with proliferative retinopathy of sickle cell disease [7]. In proliferative retinopathy, abnormal blood vessels (neovascularization) grow within the retina and extend into the vitreous. In advanced disease, the vessels can pull the retina away from the back wall of the eye causing a traction retinal detachment.

Although retinal detachment usually occurs in one eye, there is a 15% chance of developing it in the other eye, and this risk increases to 25-30% in patients who had cataracts extracted from both eyes [8].

Symptoms

A retinal detachment is commonly preceded by a posterior vitreous detachment which gives rise to these symptoms:

* flashes of light (photopsia) - very brief in the extreme temporal (outside away from the nose) part of vision
* a sudden dramatic increase in the number of floaters
* a ring of floaters or hairs just to the temporal side of the central vision
* a slight feeling of heaviness in the eye

Although most posterior vitreous detachments do not progress to retinal detachments, those that do produce the following symptoms:

* a dense shadow that starts in the peripheral vision and slowly progresses towards the central vision
* the impression that a veil or curtain was drawn over the field of vision
* straight lines (scale, edge of the wall, road, etc.) that suddenly appear curved (positive Amsler grid test)
* central visual loss

Treatment

There are several methods of treating a detached retina which all depend on finding and closing the holes (tears) which have formed in the retina.

* Cryopexy and Laser Photocoagulation

Cryotherapy (freezing) and laser photocoagulation are treatments used to create a scar/adhesion around the retinal hole to prevent fluid from entering the hole and accumulating behind the retina and excacerbating the retinal detachment. Cryopexy and photocoagulation are generally interchangeable. However, cryopexy is generally used in instances where there is a lot of fluid behind the hole;laser retinopexy will not take.

* Scleral buckle surgery

Scleral buckle surgery is an established treatment in which the eye surgeon sews one or more silicone bands (bands , tyres) to the outside of the eyeball. The bands push the wall of the eye inward against the retinal hole, closing the hole and allowing the retina to re-attach. The bands do not usually have to be removed. The most common side effect of a scleral operation is myopic shift. The operated eye generally will be 3-5 diopters more near sighted after the scleral buckle operation.

* Pneumatic retinopexy

This operation is generally performed in the doctor's office under local anesthesia. It is another method of repairing a retinal detachment in which a gas bubble ( SF6 or C3F8 gas ) is injected into the eye after laser or freezing treatment is applied to surround the retinal hole. The patient's head is then positioned so that the bubble rests against the retinal hole. Patients may have to keep their heads tilted for several days to keep the gas bubble in contact with the retinal hole. The surface tension of the air/water interface seals the hole in the retina, and allows the retinal pigment epithelium to pump the subretinal space dry and pull the retina back into place. This strict positioning requirement makes the treatment of the retinal holes and detachments that occurs in the lower part of the eyeball impractical.

* Vitrectomy

Vitrectomy is an increasingly widely used treatment for retinal detachment in countries with modern healthcare systems. It involves the removal of the vitreous gel and is usually combined with filling the eye with a gas bubble (SF6 or C3F8 gas). Advantages of this operation is that there is no myopic shift after the operation. A disadvantage is that a vitrectomy always leads to more rapid progression of a cataract in the operated eye. Another major disadvantage of the operation is that , should a vitrectomy operation fail to work, the recurrent retinal detachment is much harder to repair. As such, except for special instances, the vitrectomy operation is not usually used as the initial operation to attempt to repair a rhegmatogenous retinal detachment.

* Ignipuncture

Ignipuncture is an outdated procedure that involves cauterization of the retina with a very hot pointed instrument.[3] It was pioneered and named by Jules Gonin in the early 1900s.[3]

After treatment, patients gradually regain their vision over a period of a few weeks, although the visual acuity may not be as good as it was prior to the detachment, particularly if the macula was involved in the area of the detachment. However, if left untreated, total blindness can occur in a matter of days.

Prevention

Retinal detachment can be prevented in some. The most effective way of preventing retinal detachment is educating people to seek ophthalmic medical attention if they suffer symptoms suggestive of a posterior vitreous detachment [9]. Early examination allows detection of retinal tears which can be treated with laser or cryotherapy. This reduces the risk of retinal detachment in those who have tears from around 1:3 to 1:20.

There are some known risk factors for retinal detachment. There are also many activities which at one time or another have been forbidden to those at risk of retinal detachment, with varying degrees of evidence supporting the restrictions.

Cataract surgery is a major cause, and can result in detachment even a long time after the operation. The risk is increased if there are complications during cataract surgery, but remains even in apparently uncomplicated surgery. The increasing rates of cataract surgery, and decreasing age at cataract surgery, will inevitably lead to an increased incidence of retinal detachment.

Trauma is a less frequent cause. Activities which cause direct trauma to the eye (boxing, kick-boxing, karate and others) can cause a particular type of retinal tear called a retinal dialysis. This type of tear can be detected and treated before it develops into a retinal detachment. For this reason governing bodies in some of these sports require regular ophthalmic examination.

Individuals prone to retinal detachment due to a high level of myopia are encouraged to avoid activities where there is a risk of shock to the head or eyes, although without direct trauma to the eye the evidence base for this may not be convincing [4]. Some doctors recommend avoiding activities that increase pressure in the eye, including diving, skydiving, again with little supporting evidence. Retinal detachment does not happen as a result of straining your eyes, bending or heavy lifting.[5] Therefore, heavy weightlifting is fine.

Activities that involve sudden acceleration or deceleration also increase eye pressure and are discouraged by some doctors. These include bungee jumping,[4] but may also include rollercoaster rides.

References

1. ^ Retinal detachment. MedlinePlus Medical Encyclopedia. National Institutes of Health (2005). Retrieved on 2006-07-18.
2. ^ Ivanisevic M, Bojic L, Eterovic D. "Epidemiological study of nontraumatic phakic rhegmatogenous retinal detachment." Ophthalmic Res. 2000 Sep-Oct;32(5):237-9. PMID 10971186.
3. ^ a b Wolfensberger TJ. "Jules Gonin. Pioneer of retinal detachment surgery." Indian J Ophthalmol. 2003 Dec;51(4):303-8. PMID 14750617.
4. ^ a b http://www.emedicine.com/emerg/topic504.htm
5. ^ http://www.rnib.org.uk/xpedio/groups/public/documents/PublicWebsite/public_rnib003661.hcsp

See also

* Lattice degeneration
* Retinoschisis