Retinal detachment refers to the condition in which the retina separates from the underlying retinal pigment epithelium (RPE), becoming cut off from its nutritive and photopigment restorative properties. It may eventually die if the close connection is not restored in time.
In most cases of traumatic or acute U-shaped tears causing retinal detachment, surgery is required. There are different types of surgery. All are aimed at producing chorioretinal adhesion to seal the edges of the tear and enable the retina to reattach to the RPE. Early treatment is recommended to increase the chances of success and to prevent macular detachment, and subsequent visual loss.
In this mode of treatment, the posterior chamber of the eye is filled with an expansive gas bubble of perfluoropropane. This is not quickly absorbed, so it keeps the eye expanded and presses the retina against the RPE till the retinal detachment is repaired. This is suitable for small detachments especially in the upper part of the retina. Once the retina floats back into its correct position, the edges of the tear that led to the detachment are sealed with a laser. In other cases the edges are first treated by the application of a cryoprobe which freezes the tissue, leading to sealing of the wound. This is called cryoretinopexy.
Pneumatic retinopexy is highly dependent for its success on the maintenance of the right head posture, usually in the face-down position. This ensures that the bubble of gas presses against the back of the eyeball due to gravitational forces. This posture will have to be practiced constantly for several days or even weeks. This procedure is performed in day surgery under local anesthesia. Air travel or scuba diving is also contraindicated for several months following the surgery, because of the pressure changes involved which may cause shrinkage or expansion of the gas bubble. If any surgery requiring the use of general anesthetic is contemplated, the surgeon should be informed about the presence of the gas bubble in the eye.
Intraocular silicone oil tamponade
In this case, silicone oil is used to maintain the pressure and shape of the posterior chamber of the eye. The oil maintains a stable tamponade, but causes a change in visual acuity and must be removed surgically later. This is limited in scope, and is currently used in retinal detachments occurring in AIDS-related cytomegalovirus-induced eye infections.
Scleral buckling techniques
This is done only in a hospital setting and involves the use of a scleral buckle made of synthetic material. Through a small incision in the sclera, drainage of any subretinal fluid that has accumulated is accomplished. Next, the scleral buckle is used to indent the sclera at the point of detachment so that the retina is pushed against it, encouraging it to re-bond to the RPE. A soft or hard silicone implant is used and sutured to the sclera at the appropriate site, in the plane of the equator of the eye. This is an outpatient procedure but is usually conducted in the operating theater. Cryoretinopexy is done to seal the break in the retina as well.
In this procedure, vitreous is resected from the posterior chamber through an incision in the sclera. This removes all sources of traction from scar, gel or fibrous tissue attached to the retina. It is used when the retinal tear or detachment is relatively large. It is also performed in tractional retinal detachments which require surgery. The vitreous is replaced by sterile saline solution or other compatible solution.
In addition, a vitrectomy is performed prior to pneumatic retinopexy. In the long term, the gas will be reabsorbed and replaced by fluid produced by the eye itself. Vitrectomy may also be done along with a scleral buckling procedure.
Laser photocoagulation or cryoretinopexy
For smaller holes in the retina, cryotherapy is done using a cryoprobe or an argon laser. Cryopexy produces controlled damage to the edges of the tear using intense cold. The laser produces small burns around the edges. Both produce mild adhesive scarring and so bind down the retina to the underlying RPE. This is intended to prevent future retinal detachment from occurring by fluid seeping underneath the edges of the tear and lifting off the retina in a progressive manner. For larger holes, these are used along with vitrectomy and pneumatic retinopexy to re-attach the retina.
Prognosis of treatment
In 9 of every 10 patients, retinal detachments can be treated successfully with one or two treatments. However, it is not always possible to predict the outcome in terms of visual restoration. Several months are required to attain the final visual acuity. In a few cases vision is lost. The best outcomes are seen when the macula is unaffected at the time of repair. This requires the patient to report early with symptoms of floaters, flashes of light or loss of peripheral vision, or a veil descending over the field of vision. All patients must undergo regular eye examinations at short periods, especially in the first six weeks after surgery, when the majority of complications occur.
Reviewed by Yolanda Smith, BPharm