Retinal detachment

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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 layer of light-sensitive tissue on the back wall of the eye. The optical system of the eye focuses light on the retina much like light is focused on the film in a camera. The retina translates that focused image into neural impulses and sends them to the brain via the optic nerve. Occasionally, posterior vitreous detachment, injury or trauma to the eye or head may cause a small tear in the retina. The tear allows vitreous fluid to seep through it under the retina, 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 from the vitreous space 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.

A substantial number of retinal detachments result from trauma, including blunt blows to the orbit, penetrating trauma, and concussions to the head. A retrospective Indian study of more than 500 cases of rhegmatogenous detachments found that 11% were due to trauma, and that gradual onset was the norm, with over 50% presenting more than one month after the inciting injury.^[2]

Prevalence

The risk of retinal detachment in otherwise normal eyes is around 5 in 100,000.^[3] Detachment is more frequent in the middle-aged or elderly population with rates of around 20 in 100,000.^[4] The lifetime risk in normal eyes is about 1 in 300.^[5]

• Retinal detachment is more common in those with severe myopia (above 5–6 diopters), as their eyes are longer and the retina is stretched thin. The lifetime risk increases to 1 in 20.^[6] 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 estimated of risk of retinal detachment after cataract surgery is 5 to 16 per 1000 cataract operations.^[7] The risk may be much higher in those who are highly myopic, with a frequency of 7% reported in one study.^[8] Young age at cataract removal further increased risk in this study. Long term risk of retinal detachment after extracapsular and phacoemulsification cataract surgery at 2, 5, and 10 years was estimated in one study to be 0.36%, 0.77%, and 1.29%, respectively.^[9]

• Tractional retinal detachments can also occur in patients with proliferative diabetic retinopathy ^[10] or those with proliferative retinopathy of sickle cell disease.^[11] 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 have had cataracts extracted from both eyes.^[6]

Symptoms

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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 peripheral (outside of center) 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

(None of this is to be confused with the broken retnea which is generally the tearing of muscle and nerve behind the eye)

Treatment of Rhegmatogenous Retinal Detachment

General Principles

1 Find all retinal breaks 2 Seal all retinal breaks 3 Relieve present (and future) vitreoretinal traction

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

• Cryopexy and Laser Photocoagulation

Cryotherapy (freezing) or laser photocoagulation are occasionally used alone to wall off a small area of retinal detachment so that the detachment does not spread.

• 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 sclera (the white outer coat of the eyeball). The bands push the wall of the eye inward against the retinal hole, closing the break or reducing fluid flow through it and reducing the effect of vitreous traction thereby allowing the retina to re-attach. Cryotherapy (freezing) is applied around retinal breaks prior to placing the buckle. Often subretinal fluid is drained as part of the buckling procedure. The buckle remains in situ. The most common side effect of a scleral operation is myopic shift. That is, the operated eye will be more short sighted after the operation. Radial scleral buckle is indicated to U-shaped tears or Fishmouth tears and posterior breaks. Circumferential scleral buckle indicated to multiple breaks, anterior breaks and wide breaks. Encircling buckles indicated to breaks more than 2 quadrant of retinal area, lattice degeration located on more than 2 quadrant of retinal area, undetecable breaks, and proliferative vitreous retinopathy.

• 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 which laser or freezing treatment is applied to 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 suck 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. This procedure is usually combined with cryopexy or laser photocoagulation.

• Vitrectomy

Vitrectomy is an increasingly used treatment for retinal detachment. It involves the removal of the vitreous gel and is usually combined with filling the eye with either a gas bubble (SF₆ or C₃F₈ gas) or silicon oil. Advantages of using gas in this operation is that there is no myopic shift after the operation and gas is absorbed within a few weeks. Silicon oil (PDMS), if filled needs to removed after a period of 2–8 months depending on surgeon's preference. Silicon oil is more commonly used in cases associated with proliferative vitreo-retinopathy (PVR). A disadvantage is that a vitrectomy always leads to more rapid progression of a cataract in the operated eye. In many places vitrectomy is the most commonly performed operation for the treatment of retinal detachment.

Results of Surgery

85 percent of cases will be successfully treated with one operation with the remaining 15 percent requiring 2 or more operations. 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 could occur in a matter of days.

Prevention

Retinal detachment can sometimes be prevented. The most effective means is by educating people to seek ophthalmic medical attention if they suffer symptoms suggestive of a posterior vitreous detachment.^[12] 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, inevitably lead to an increased incidence of retinal detachment.

Trauma is a less frequent cause. Activities which can cause direct trauma to the eye (boxing, kickboxing, karate, etc.) may 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 eye 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 be unconvincing.^[6] Some doctors recommend avoiding activities that increase pressure in the eye, including diving, skydiving, again with little supporting evidence. According to one medical website, retinal detachment does not happen as a result of straining your eyes, bending or, heavy lifting.^[13] Therefore, heavy weightlifting would appear to be fine. However, two recent scientific articles ^[14][15] have noted cases of retinal detachment or maculopathy due to weightlifting (specifically with the Valsalva method), and a third documented an increase in blood pressure in the eye during weightlifting ^[16]. Moreover, a recent case-control study focusing on myopic subjects supports the hypothesis that heavy lifting (or manual handling) requiring Valsalva maneuver may be a risk factor for retinal detachment ^[17].

Activities that involve sudden acceleration or deceleration also increase eye pressure and are discouraged by some doctors. These include bungee jumping^[6] and drag racing,

References

See also

• Lattice degeneration
• Retinoschisis

External links

• The Vitreoretinal Company Manufacturer of Medical Devices for Retinal Detachment Surgery (MIRA).
• Retinal Detachment Resource Guide from the National Eye Institute (NEI).
• Overview of retinal detachment from eMedicine
• Guidelines from the American Academy of Family Physicians
• Retinal detachment information from WebMD
• Retinal detachment information from the Merck Manual
• A Diary of Retinal Detachment
• Royal National Institute for the Blind(UK )Site
• Retinal Detachment Frequently Asked Questions
• Detached Retina and The Treatment Required
• Engineering a new tool for observing the retina and preventing detachment Ingenia, March 2007
• Steven Fisher's Retinal Cell Biology lab at the University of California, Santa Barbara