Photocoagulation Therapy Health Article

Risk factors for retinal detachment

Retinal detachment is associated with a number of different factors and conditions, including:

• extreme nearsightedness
• genetic factors (retinal detachment tends to run in families)
• premature birth (the risk of ROP is highest in premature infants weighing less than 2.2 lb [1 kg] at birth)
• type 1 or type 2 diabetes
• cataract surgery
• sickle cell disease
• Coats' disease
• Eales' disease
• Marfan's syndrome
• breast cancer or melanoma
• leukemia
• history of previous retinal detachment
• age (Retinal detachment is most common in people between the ages of 40 and 70.)
• traumatic injury to the eye
• laser in situ keratomileusis surgery (LASIK, a procedure done to correct vision without the need for glasses or contact lenses)

Photocoagulation therapy for retinal detachment is usually performed with an argon laser. A laser is a device that produces high-intensity, narrowly focused monochromatic light by exciting atoms and causing them to give off their energy in phases. The word laser comes from "light amplification by stimulated emission of radiation." An argon laser uses ionized argon to generate its light, which is in the blue-green portion of the visible light spectrum.

In a laser photocoagulation treatment, the patient is asked to sit in front of the instrument. After applying anesthetic eye drops, the ophthalmologist places a contact lens on the patient's eye and focuses the laser beam through it. He or she operates the laser by foot. The patient may see a brief burst of blue-green light. When the laser beam reaches the retina at the back of the eye, its light is absorbed by the pigment in the cells and converted to heat, which seals the edge of the retinal detachment against the underlying choroid. The procedure is short, taking about 10–30 minutes.

Diagnosis

The diagnosis of retinal detachment requires direct examination of the eye as well as taking the patient's medical history. The diagnosis may be made in some cases by an optometrist, who is a health professional qualified to examine the eye for diseases and disorders as well as taking measurements for corrective lenses. If the symptoms of RD appear suddenly, however, the patient is more likely to be diagnosed by an ophthalmologist, who is a physician specializing in treating disorders of the eye.

PATIENT HISTORY. Retinal detachment is not usually painful, and the patient's eye will look normal from the outside. In almost all cases, a patient with RD consults a doctor because he or she is having one or more of the following visual disturbances:

• blurring of vision that is not helped by blinking the eye
• a gray or black curtain or shade coming across the field of vision from one direction
• floaters, which appear as moving black spots in front of the eye (The sudden appearance of a large group, or "shower," of floaters is a serious symptom of RD.)
• flashes of light
• objects appearing wavy or distorted in shape
• blind spot in the visual field

The visual symptoms of retinal detachment may develop either gradually or suddenly. In a very small number of cases, a sudden retinal detachment may cause complete loss of vision in the affected eye.

Patients who have gone to a primary care physician or emergency room for these visual symptoms are referred to an ophthalmologist. Many ophthalmologists will give patients a piece of paper with a circle on it and ask them to draw what they are seeing on the circle in the area corresponding to the part of their visual field that is affected. In some cases, the location of the spots, light flashes, or shadows that a patient sees is a clue to the part of the retina that is detached.

The ophthalmologist will take a patient history, asking about a family history of eye disorders; previous diseases or disorders of the eye; other diseases or disorders that the patient may have, particularly diabetes or sickle cell disease; and a history of head trauma, direct blows to the eye, or surgical removal of a foreign body from the eye. If the patient suffered a head or eye injury within the past six months, the ophthalmologist will ask whether the visual disturbances started at the time of the injury or several months later.

EYE EXAMINATION. After taking the history, the ophthalmologist will examine the eye itself. This examination has several parts, including:

• A test of visual clarity or sharpness. This test is the same one used by an optometrist when fitting a patient for glasses or contact lenses.
• An external check for bleeding or any other signs of trauma to the eye.
• A test that measures the response of the pupil of the eye to changes in light intensity. One sign of RD is a difference in the pupillary reaction between the affected eye and the normal one. The pupil will not contract as far as it normally does when the doctor shines a light into the affected eye.
• A test that measures the amount of fluid pressure inside each eyeball. In RD, the affected eye typically has a lower pressure measurement than the other eye.
• Examination of the eye with a slit lamp, which is an instrument with a high-intensity light source that can be focused as a thin sliver of light. The examiner uses the slit lamp together with a binocular ophthalmoscope (an instrument that looks like a microscope with two eyepieces) in order to check first the front and then the back of the eye for any abnormalities. To check the front part, the doctor will touch the side of the eye with a strip of paper containing an orange dye. The dye stains the film of tear fluid on the outer surface of the eye, making it easier to see the structures in the front of the eye. Patients with RD usually have normal results for this part of the slit-lamp examination. In the second part, the doctor puts some drops in the patient's eye to make the pupil dilate. This procedure allows him or her to see the structures in the back of the eye. If the patient has RD, the doctor may see the retina lifted upward or forward, possibly
  moving back and forth. The retina will have a grayish color with darker blood vessels visible. It may have a pitted surface resembling an orange peel, and there may also be a line visible at the edge of the detachment.

LABORATORY AND IMAGING STUDIES. Today, there are no laboratory tests for retinal detachment. Ultrasound, however, can be used to diagnose retinal detachment if the doctor cannot see the retina with a slit lamp because of cataracts or blood seeping into the vitreous body. If the RD is exudative, ultrasound can be used to detect a tumor or hemorrhage underneath the retina.