There are quite a few links to sites that discuss retina issues on the "Medical Info" page. This is just a basic overview. Not all the links in the article will work, but here is the link to the web page:
Retinal tears commonly occur when there is traction on the retina by the vitreous inside the eye.In a child’s eye, the vitreous has an egg-white consistency and is firmly attached to certain areas of the retina.Over time, the vitreous gradually becomes thinner, more liquid and separates from the retina.This is known as a posterior vitreous detachment (PVD).
PVDs are typically harmless and cause floaters in the eye; but in some cases, the traction on the retina may create a tear.Retinal tears frequently lead to detachments as fluids seep underneath the retina, causing it to separate and detach.
A retinal detachment occurs when the retina’s sensory and pigment layers separate.Because it can cause devastating damage to the vision if left untreated, retinal detachment is considered an ocular emergency that requires immediate medical attention and surgery.It is a problem that occurs most frequently in the middle-aged and elderly.
There are three types of retinal detachments.The most common type occurs when there is a break in the sensory layer of the retina, and fluid seeps underneath, causing the layers of the retina to separate.Those who are very nearsighted have undergone eye surgery, or have experienced a serious eye injury are at greater risk for this type of detachment.Nearsighted people are more susceptible because their eyes are longer than average from front to back, causing the retina to be thinner and more fragile.
The second most common type occurs when strands of vitreous or scar tissue create traction on the retina, pulling it loose.Patients with diabetes are more likely to experience this type.
The third type happens when fluid collects underneath the layers of the retina, causing it to separate from the back wall of the eye.This type usually occurs in conjunction with another disease affecting the eye that causes swelling or bleeding.
Signs and Symptoms
·“Wavy,” or “watery” vision
·Veil or curtain obstructing vision
·Shower of floaters that resemble spots, bugs, or spider webs
·Sudden decrease of vision
Detection and Diagnosis
Retinal detachments are usually found because the patient calls the doctor’s office with a symptom listed above.It is critical that these problems are reported early, because early treatment can greatly improve the chance of restoring vision.
The doctor makes the diagnosis of a retinal detachment after thoroughly examining the retina with ophthalmoscopy.The retinal surgeon’s first concern is to determine whether the macula (the center of the retina) is attached.This is critical because the macula is responsible for the central vision.Whether or not the macula is attached determines the type of corrective surgery required and the patient’s chances of having functional vision after the operation.
Ultrasound imaging of the eye is also very useful for the doctor to see additional detail of the condition of the retina from several angles. Treatment
There are a number of ways to treat retinal detachment.The appropriate treatment depends on the type, severity and location of the detachment.
Pneumatic retinopexy is one type of procedure to reattach the retina.After numbing the eye with a local anesthesia, the surgeon injects a small gas bubble into the vitreous cavity.The bubble presses against the retina, flattening it against the back wall of the eye.Since the gas rises, this treatment is most effective for detachments located in the upper portion of the eye.In order to manipulate the bubble into the ideal location, the surgeon may ask the patient to keep his or her head in a specific position.
The gas bubble slowly absorbs over the next 1-2 weeks.At that time, an additional procedure is usually performed to “tack down” the retina.This can be done either with cryotherapy, a procedure that uses nitrous oxide to freeze the retina, sealing it in place, or with laser.Local anesthesia is used for both procedures.
Some types of retinal detachments, because of their location or size, are best treated with a procedure called a scleral buckle.With this technique, a tiny sponge or band made of silicone is attached to the outside of the eye, pressing inward and holding the retina in position.After removing the vitreous gel from the eye with a procedure called a vitrectomy, the surgeon usually seals a few areas of the retina into position with laser or cryotherapy.The scleral buckle is not visible and remains permanently attached to the eye.This technique of reattaching the retina may elongate the eye, causing nearsightedness.
In rare cases where other types of retinal detachment surgeries are either inappropriate or unsuccessful, silicone oil may be used to reattach the retina.The vitreous gel is removed and replaced with silicone oil, which presses the retina into place.While the oil is inside the eye, the vision is extremely poor.After the retina has resealed itself against the back of the eye, a second procedure may be performed to remove the oil.
Laser photocoagulation is a technique employed by retinal surgeons to treat a number of eye conditions, one of which is the exudative (wet) form of MD. In this treatment, laser light rays are directed into the eye focusing on abnormal blood vessels that are growing beneath the retina. This laser, with the heat from a fine-point laser beam, cauterizes the vessels to seal them from further leakage in the hope of preventing further vision loss. It does not restore lost vision, so it is critical that the eye be treated as early as possible in the course of the disease.
Photocoagulation is also known as the "hot" laser treatment, because it also destroys surrounding healthy tissue while coagulating the leakage from abnormal vessel growth. Only a small percentage of people meet the requirements for this type of laser, because those with occult (hidden) or subfoveal (center of macula) leakage are usually not candidates.
Photocoagulation laser surgery is done on an outpatient basis. Eye drops will be given to dilate the pupil and numb the eye. The treatment is performed while the patient is seated in a chair, similar to the one used for regular eye examinations. The patient remains awake and comfortable, but some may experience mild pain, which can usually be relieved with non-prescription medication such as acetaminophen (Tylenol). The laser treatment usually takes less than thirty minutes to complete, and the patient can go home immediately following surgery. It could take several weeks before knowing if laser surgery has been successful, and many patients will need more than one treatment to control their eye condition in order to try preventing further vision loss. It is not a cure, but a temporary treatment designed to postpone deteriorating vision loss
WHAT IS CRYOTHERAPY?
Retinal cryotherapy uses intense cold to induce a choridoretinal scar and to destroy retinal and/or choroidal tissue. Cryotherapy involves apposing a metal probe against the eye. The tip of the probe is then cooled as a result of the rapid expansion of gases within the probe tip. The formation of water crystals followed by rapid thawing results in cellular disruption. Tissue destruction is followed by a healing response and scar tissue formation. Usually, retinal cryotherapy is administered under local anesthesia.
Retinal cryopexy (retinal cryotherapy) is used to treat retinal breaks; to destroy areas of ischemic retinal tissue; and to induce regression of retinal neovascularization (particularly if the surgeon feels that laser photocoagulation treatment cannot be administered); to directly destroy abnormal retinal blood vessels that are causing visual loss (for example, in Coats' disease); and to destroy small intraocular tumors (for example, selected retinoblastoma tumors).