Common Retinal Procedures
|Fundus Photography||Optical Coherence Tomography|
|Fluorescein Angiography||Visual Field Analysis|
|Photocoagulation (In-Office Laser)||Silicone Oil|
|Gas-Fluid Exchange||Intraocular Injection|
Fundus photography involves photographing the inside of the eye to document retinal and optic nerve pathology. For many years traditional 35-millimeter film was used in ophthalmic photography and is still used to some degree, but the vast majority of retina offices have adopted digital imaging systems. A special camera captures high-resolution images of the retina, and then the images are displayed on a large monitor. The physician can then review the images with the patient immediately.
Imaging of the retina can show incredible detail, however it cannot show blood flow in the retinal tissue. It can document conditions such as bleeding inside the eye, but rarely will show the source of the bleeding. This is where a circulation test called fluorescein angiography is extremely helpful. Similar to fundus photography, fluorescein angiography consists of capturing rapid-sequence images of the back of the eye after injecting a special dye intravenously. A vein in the patient's hand or arm is used for the injection. The resulting images show the physician the circulation in the retina, and will reveal any abnormalities. Patients may notice a discoloration of their skin for up to twelve hours and urine discoloration for up to thirty-six hours after the test.
Optical Coherence Tomography (OCT) is a relatively new technology that is used to create cross-sectional images of the retina and optic nerve head. A special light beam is directed at the tissue and scanned across the surface in a linear fashion. The light that is directly reflected is interpreted by the instrument to form an image. The portion of the light that is scattered is filtered out. OCT gives the surgeon a side-view image of the retina, as opposed to a front-view obtained with standard imaging.
Some diseases such as glaucoma and optic nerve problems can lead to loss of peripheral or side vision. Visual Field analysis consists of "mapping" a patient's visual field. Using a special instrument called a visual field analyser, the patient stares at a central point and is presented with small points of light at various locations throughout the peripheral areas of vision. The patient depresses a handheld button when the light is seen. The lights vary in intensity and the instrument frequently checks to make sure the patient is fixating properly.
Photocoagulation or laser is performed usually in the physician's office. A topical anesthetic eye drop is instilled, and then a special surgical contact lens is held against the front of the eye by the surgeon. A laser beam is fired through the lens and directed at the area of retina requiring treatment. Laser is used to "spot-weld" retina around a retinal tear or hole to prevent retinal detachment. It is also used frequently to treat patients with diabetic retinopathy. Patients usually experience blurring immediately following the treatment, which clears gradually. Patients requiring heavy laser may require injectable anesthetic and the eye will be patched for several hours after the treatment.
Vitrectomy is a surgical procedure in which the vitreous gel inside the eye is removed, and then replaced with a special saline solution. The procedure is actually called the trans-pars plana vitrectomy, because small, needle-like devices are inserted through the wall of the eye in an area known as the pars plana.
Vitrectomy is performed for many different diagnoses, including retinal detachment, vitreous hemorrhage, and macular pucker. Vitrectomy is an outpatient procedure done under local anesthetic with intravenous sedation. Most patients experience little or no post-operative discomfort, and usually return to normal activities in a few days.
Vitrectomy is sometimes accompanied by secondary procedures such as endophotocoagulation, gas-fluid exchange or membrane peeling.
Endophotocoagulation is laser performed inside the eye during vitrectomy. A special needle-sized laser probe is inserted through the wall of the eye, and the surgeon can photocoagulate, or laser areas of the retina that require treatment.
The gas-fluid exchange may be performed after the vitrectomy portion of surgery is complete. A bubble of a special gas is introduced into the eye in place of some of the saline solution used during vitrectomy. Some retinal conditions require pressure be put on the retina to hold it in place while healing, such as retinal detachment and macular hole. The gas bubble floats against the retina, providing the pressure, or tamponade. Because the gas bubble floats up, against gravity, special positioning may be required of the patient to ensure the bubble contacts the proper area of the retina. The gas is slowly absorbed by the body over several days to two weeks.
Occasionally a patient who has been diagnosed with retinal detachment or macular hole may be physically incapable of postoperative positioning after vitrectomy and gas-fluid exchange. An alternative procedure involves filling the eye with special silicone oil. The oil acts like a cast with a broken bone and holds the retina in place. The oil remains in the eye usually for several months or longer, but requires a second procedure to remove it.
The membrane peel is exactly what it sounds like; a membrane, such as described with macular pucker is physically peeled off of the retinal surface. The surgeon uses a needle-sized instrument with tiny jawed forceps on the tip. After vitrectomy, the membrane is peeled from the retina, and then sometimes an anti-inflammatory medicine is used inside the eye to quiet swelling.
Scleral buckling is performed to repair some retinal detachments. A silicone and plastic band is placed around the eye, and tightened like a belt. This brings the wall of the eye inward, toward the detached retina. The fluid behind the retina is then drained. The surgeon then uses cryotherapy or freezing treatment to seal any retinal tears. The scleral buckle acts as a support structure for the retina and usually remains in place for the patient's lifetime. The buckle is not visible from an observer's standpoint.
Some diseases such as Wet AMD (Age-related Macular Degeneration) may require special medications to be injected into the eye. These medications usually remain effective inside the eye for several weeks, providing long-term thereapy. Intraocular injections can usually be performed in the office.