Laser Surgery
LASER SURGERY
There are several types of lasers used to treat various disorders in the eye and currently lasers are being used to reduce vision loss from glaucoma, secondary cataracts, diabetes, blocked blood vessels, retinal tears, retinal detachments and macular degeneration.
The laser is a bright light that can be focused to a very small spot on the retina. When this highly focused beam of light hits the retina, the tissue heats up and is cauterized or coagulated. The laser treatments can be performed in the office or in the outpatient department of a hospital. The laser treatment is usually not painful. The patient is given drops to dilate the pupil and then either a local anesthetic is injected behind the eyelid to numb the eye and keep it steady during the laser treatment, or a numbing drop is used. The treatment itself takes 10-15 minutes. After treatment the eye is patched for several hours but normal activities can usually be resumed the next day.
LASER FOR DIABETIC RETINOPATHY
Background diabetic retinopathy can cause swelling or edema in the retina which can cause a decrease in visual acuity. In the case of a macular edema, caused by specific leaks in the blood vessels, laser treatment can often effectively seal the individual leaks preventing further loss of vision and, at times, improving the vision as well. In other cases the leakage is diffuse or generalized, and a laser treatment in the form of a "grid" is applied; again, with the intention of stabilizing vision. Unfortunately there are cases when the leakage is so far advanced or the circulation to the macula is so poor that laser treatment will not be successful. These facts are important to realize because sometimes the stabilization or improvement in vision is not what the patient hoped for. Realistically, in most cases a stabilization of vision is the most that can be hoped for and 2 or more laser treatments in each eye may be necessary. Laser for diabetic retinopathy is rarely a one time only treatment.
A nationwide study showed that patients with background diabetic retinopathy who had laser treatment, did twice as well as a similar group that did not have treatment. Laser treatment is usually more beneficial if it is carried out early and the diabetes is well controlled.
Placement of coagulations in the inferior macular region in a panretinal photocoagulation pattern in the treatment of patients with diffuse diabetic maculopathy.
Placement of coagulations in the inferior macular region in a panretinal photocoagulation pattern in the treatment of patients with diffuse diabetic maculopathy.
LASER FOR MACULAR DEGENERATION
About 10% of patients with macular degeneration may develop abnormal blood vessels under the retina. The blood vessels may leak or hemorrhage causing a marked decrease in the central vision. It is for this group of patients that laser can sometimes be useful in the treatment of macular degeneration.
Fluorescein angiography is perhaps the best and sometimes the only way to determine which eyes can be treated with laser. In this test a vegetable dye is injected into a vein in the patient's hand or arm. The dye is carried by the blood stream to the retina and a rapid sequence of pictures are taken. If there are abnormal blood vessels under the retina, they will show up on the special pictures. In this way, the exact location and extent of the abnormal blood vessels can be determined.
The laser is then used to cauterize or coagulate the abnormal blood vessels. The laser is not painful but the laser needs to be aimed accurately. Occasionally an injection of local anesthetic is given to prevent movement of the eye during the laser. After treatment the eye will be patched for several hours and normal activities can be resumed the next day. A repeat examination is performed 7-10 days later to ensure that the abnormal blood vessels have been adequately coagulated.
The laser is then used to cauterize or coagulate the abnormal blood vessels. The laser is not painful but the laser needs to be aimed accurately. Occasionally an injection of local anesthetic is given to prevent movement of the eye during the laser. After treatment the eye will be patched for several hours and normal activities can be resumed the next day. A repeat examination is performed 7-10 days later to ensure that the abnormal blood vessels have been adequately coagulated.
LASER FOR PROLIFERATIVE DIABETIC
A second and more potentially serious form of diabetic retinopathy is called Proliferative Diabetic Retinopathy. In this condition, new, fragile blood vessels develop on the surface of the retina. These blood vessels can break and bleed causing a severe decrease in vision. The treatment of proliferative diabetic retinopathy is a laser technique called "PanRetinal Photocoagulation" (PRP). In this procedure 1200-3000 separated laser burns are applied to the peripheral retina in an attempt to redirect blood flow to the more important central areas. This tends to curtail further development of new blood vessels and in time usually causes the already present abnormal blood vessels to regress or disappear. When treatment is given at the appropriate time, severe vision loss is reduced by 60%.
The laser treatment usually requires 2-3 treatment sessions per eye, (the first two spaced about 2 weeks apart and the third, if necessary, 1-2 months later.) The treatment may cause some loss of side vision and a decrease in night vision but the loss is usually not very noticeable to the patient and is far better than the marked loss of vision caused by a hemorrhage.
The laser treatment usually requires 2-3 treatment sessions per eye, (the first two spaced about 2 weeks apart and the third, if necessary, 1-2 months later.) The treatment may cause some loss of side vision and a decrease in night vision but the loss is usually not very noticeable to the patient and is far better than the marked loss of vision caused by a hemorrhage.
LASER FOR RETINAL TEARS OR RETINAL DETACHMENTS.
Changes due to aging, disease or a sudden blow to the eye, can all cause a retinal tear or a retinal detachment. Most cases occur because of age related changes occurring in the eye and the vitreous gel. As the vitreous gel changes with age it shrinks and pulls away from the retina. If it pulls hard enough a tear or hole can occur. This retinal tear or hole can allow fluid to pass through it behind the retina causing a retinal detachment.
Punctate, linear, contiguous coagulations (500u to 1,000u) around the border of a tear in an area of attached retina, producing a double linear row of barrier impacts.
In order to prevent the formation of a retinal detachment, a seal must be created around the tear using either of two techniques; cryo therapy or laser photocoagulation. Using either of these two techniques, scars are created at the edges of the tear which, require several weeks to become firm.
Punctate, linear, contiguous coagulations (500u to 1,000u) around the border of a tear in an area of attached retina, producing a double linear row of barrier impacts.
In order to prevent the formation of a retinal detachment, a seal must be created around the tear using either of two techniques; cryo therapy or laser photocoagulation. Using either of these two techniques, scars are created at the edges of the tear which, require several weeks to become firm.
LASER FOR GLAUCOMA
Glaucoma is a condition where the pressure inside the eye is too high and damage is occurring. There are many types of glaucoma but most types of glaucoma can be classified as open angle glaucoma or closed angle glaucoma.
Open angle glaucoma is the most common and forms when the drains of the eye are unable to allow fluid to drain out of the eye easily. This causes a higher pressure inside the eye to occur. Laser can help open the drains and allow fluid to drain out of the eye more easily, resulting in a lower eye pressure.
Closed angle glaucoma occurs when the iris (the colored part of the eye) is pushed forward and actually blocks the drains. This type of glaucoma will usually appear suddenly causing a marked decrease in the vision and a very high pressure causing pain and redness. The laser is used to create a hole in the iris and allow fluid to pass through the iris to the drains, resulting in a decrease in the eye pressure. This is a procedure which should be performed as soon as possible after the onset of the high pressures.
Closed angle glaucoma occurs when the iris (the colored part of the eye) is pushed forward and actually blocks the drains. This type of glaucoma will usually appear suddenly causing a marked decrease in the vision and a very high pressure causing pain and redness. The laser is used to create a hole in the iris and allow fluid to pass through the iris to the drains, resulting in a decrease in the eye pressure. This is a procedure which should be performed as soon as possible after the onset of the high pressures.
LASER FOR CATARACTS
There is a common misconception that cataracts can be cured with the use of a laser beam. Fortunately, some clouding following cataract surgery can be cured with the use of a laser called a Yag laser. These cataracts are called "secondary cataracts" or "after cataracts" because they occur after a cataract surgery has already been performed. When your doctor performed the cataract surgery, he left the capsule of the cataract untouched. This allows the initial cataract surgery to be performed more safely and to reduce the chance of complications following cataract surgery such as a retinal detachment or the development of swelling of the retina. At the time of surgery the capsule is clear. However, in about 30% of individuals, it becomes cloudy and produces the same symptoms as the original cataract. A hole in the capsule can safely be created using the Yag laser avoiding the need for a second operation.