Procedure Practice 10/15/98 - Coding Recommendations

Feature Article 10/15/98:

The Eye - Part 2
Disorders of the Retina, Vitreous, Uvea, Cornea, Conjunctiva and Adnexa

Disorders - Diagnostic Tools and Techniques - Surgical Procedures
    

Last month, we reviewed the anatomy of the eye and ocular adnexa and covered glaucoma, cataracts, and refractive errors. You can access our September feature to review the anatomy section. This month we cover diseases of the retina and vitreous, uveal tract, cornea, conjunctiva, and ocular adnexa, along with related diagnostic imaging techniques and surgical procedures.

Disorders
  

Retinal and Vitreous Disorders

Vitreous Detachment

Most of the serious retinal problems which require surgery are caused by problems with the vitreous, the clear jelly-like substance which fills the space in the eye. With age, the vitreous becomes more fluid. As the eyeball moves, small pockets of liquid vitreous can move around inside the vitreous cavity. This movement causes the vitreous to pull on the retina and, over time, the vitreous can separate from the retina. This is called posterior vitreous detatchment (PVD), because it usually happens at the back of the eye. When PVD occurs, the detached vitreous tugs on the retina. The brain interprets these tugs as flashes or large spots in the vision. The vitreous can also become stringy and form visible strands that appear in the field of vision as floating threads or small spots and circles. These bits of detached vitreous are called floaters. Provided no other retinal disease is present, they do not threaten vision.

Retinal Tear and Vitreous Hemorrhage

Where the vitreous is securely attached to the retina, vitreous detachment may cause the retina to tear. If the retina tears across a blood vessel, vitreous hemorrhage results. Small amounts of bleeding cloud vision. More severe bleeding leads to a mass of red or black lines, and vision may become very dark. A retinal tear is a serious problem; vitreous hemorrhage is even more serious.

Retinal Detachment

A retinal tear is considered serious because the vitreous liquid may leak through the tear and collect under the retina. Gradually, the build up of liquid separates the retina from the wall of the eye, a condition called retinal detachment.

Diabetic Retinopathy

This retinal problem affects people who have diabetes. It occurs when the blood vessels that supply blood to the retina are damaged. It often has no symptoms until it is quite advanced. If untreated, it can lead to blindness. The types of diabetic retinopathy are background or nonproliferative retinopathy and proliferative retinopathy.

• Background retinopathy is an early form of diabetic retinopathy that occurs when damaged blood vessels in the retina bleed or leak fluid. The leakage causes the retina to swell and form deposits called exudates. Vision changes may not be noticed at this stage of disease, but more advanced forms of retinopathy may develop that can seriously impair vision. When fluid collects in the macula (macular edema), near vision becomes impaired.
     
• In proliferative retinopathy, fragile new blood vessels grow on the surface of the retina. These new blood vessels are called neovascularization. Neovascularization can lead to serious vision problems if the new vessels break and bleed into the vitreous. When the vitreous becomes clouded with blood, light is prevented from passing through the eye to the retina, distorting vision. The new blood vessels can also cause scar tissue to develop. The scar tissue can pull the retina away from the back of the eye, causing retinal detachment. In addition, abnormal blood vessels can grow on the iris and lead to glaucoma.

Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a potentially blinding eye disorder in low birthweight infants. ROP primarily affects premature infants weighing about 2¾ pounds (1250 grams) or less and having a gestational age of less than 31 weeks. ROP is caused when abnormal blood vessels grow and spread throughout the retina. In the majority of premature babies with ROP, the abnormal vessels heal completely before the baby is one year old. In some infants the blood vessels cause scarring in the retina as they heal. These babies may have to wear glasses for myopia. They may also develop lazy eye (amblyopia) or strabismus. In the most severe cases, the blood vessels in the retina continue growing incorrectly and form a large amount of scar tissue, which can shrink and cause retinal detachment. Fortunately, this happens only in a very small number of ROP cases (about 4.5%).

Age-Related Macular Degeneration

An eye disease causing increasing concern among ophthalmologists is age-related macular degeneration (AMD). AMD occurs in two forms, "dry" and "wet." It is a disease of the macula, the tiny area in the retina that produces the sharp, central vision required for "straight ahead" activities such as reading and driving. A person with AMD loses this clear, central vision. AMD is the leading cause of severe visual impairment and blindness in Americans 60 years of age and older. One of the most common early signs of AMD is the presence of tiny yellow deposits on the retina called drusen. The presence of drusen alone does not indicate disease, only that the eye is at risk for developing more severe AMD.

• Dry AMD: Scientists are uncertain of the causes of dry AMD, and to date there is no effective treatment for this form of macular degeneration. The disease causes slow deterioration of light-sensing cells in the macula with subsequent reduction of central vision. About 90 % of people with AMD have this type of the disease.
     
• Wet AMD (choroidal neovascularization): If dry AMD progresses, new blood vessels grow beneath the macula. These vessels often leak blood and fluid, causing rapid damage to the macula and quickly leading to loss of central vision. Although only 10 % of those with AMD have this type of the disease, wet AMD accounts for 90 % of all blindness resulting from AMD.

Cytomegalovirus Retinitis

CMV retinitis is an eye disease that occurs in severely immune-compromised patients. The condition is often a complication of AIDS. The cytomegalovirus attacks the retina, causing inflammation and bleeding. Eventually the virus damages the retina and may cause blindness.

Retinitis Pigmentosa

Retinitis pigmentosa, or RP, is a term that describes a group of chronic, progressive hereditary diseases of the eye. RP is characterized by a degeneration of the rods and cones as well as abnormal pigmentation. The earliest symptom of RP is night blindness, which may be first noticed in childhood. As the disease progresses, the field of vision narrows leading to tunnel vision. Decreasing vision is accompanied by clumping of retinal pigment which is detectable under ophthalmoscopic examination.

Researchers believe that RP is caused by mutations in the genes responsible for normal vision. Current research is focusing on analysis of the DNA from blood cells in search of the gene abnormalities responsible for these effects.
   

Uveal Tract Disorders

Uveitis

After diabetes and macular degeneration, uveitis is the third leading cause of blindness in the US. Uveitis, as the name implies, is an inflammation of the uveal tissues, chiefly the iris and ciliary body, which can be either chronic or acute. The chronic form is more often associated with systemic disorders including ankylosing spondylitis, inflammatory bowel disease, juvenile rheumatoid arthritis, Reiter's syndrome, sarcoidosis, tuberculosis, and Lyme disease. Occasionally, inflammatory reactions in adjacent tissues (e.g., keratitis) can induce a secondary uveitis. Acute uveitis is usually due to direct trauma to the eye or ocular adnexa.

Hyphema

Hyphema is the presence of blood in the anterior chamber of the eye. The condition may occur as the result of a blunt trauma to the eye or orbit. Symptoms include blurred vision, pain, photophobia, and tearing. Hyphemas are described by the amount of anterior chamber (AC) they occupy:

Grade 1 = less than one-quarter of the visible volume of the AC

Grade 2 = one-quarter to one-half of the visible volume of the AC

Grade 3 = one-half to three-quarters of the visible volume of the AC

Grade 4 = complete filling of the visible AC

Hyphema formation occurs in one of two ways. Either direct forces cause mechanical tearing of the delicate vasculature of the iris, or concussive trauma creates rapidly rising intravascular pressure within these vessels, resulting in rupture. Blood in the AC is, by itself, not necessarily harmful. However, if quantities are sufficient it may obstruct the outflow of aqueous humor, resulting in glaucoma.

Synechiae

Adhesions of the iris to another part of the anterior segment of the eye are called synechiae. The iris may become adherent to the lens (posterior adhesions) or to the cornea (goniosynechiae). Chronic or recurrent uveitis is the most common cause of adhesion formation.

Choroidal Melanomas

Choroidal melanomas may be benign (choroidal nevus) or malignant. Under ophthalmoscopic exam a benign nevus appears as a small, flat, or slightly raised gray lesion with indistinct margins. The malignant choroidal melanoma appears as a mottled, often significantly elevated lesion, ranging in coloration from white to greenish-gray. Retinal detachments are commonly associated with this malignancy. Most malignant melanomas are much larger than benign lesions at the time of diagnosis.

Both benign and malignant choroidal melanomas are accumulations of melanocytes in the uvea. In a choroidal nevus, these melanocytes are normal in form and function. In malignant melanoma, the cells undergo neoplasia, reproducing at a faster rate than usual and resulting in a dysfunctional tumor mass. This tumor is capable of local extension and distant metastasis. While most choroidal nevi do not progress to cancer, approximately 1:100,000 benign lesions do convert to malignancy. Malignant choroidal melanoma is the most common cancer originating in the eye.
   

Corneal and Conjunctival Disorders

Keratoconus

The most common corneal dystrophy in the United States, keratoconus is a progressive thinning process that may be accompanied by scarring. Keratoconus leads to progressive nearsightedness, astigmatism, and a cone-shaped cornea. This abnormal curvature changes the cornea's refractive power, producing moderate to severe distortion (astigmatism) and blurred vision.

Studies indicate that keratoconus stems from one of several causes:

1. An inherited corneal abnormality;
2. An eye injury, e.g., excessive eye rubbing or wearing hard contact lenses for many years;
3. Certain eye diseases such as retinitis pigmentosa or retinopathy of prematurity; or
4. Systemic diseases such as Down's syndrome and Addison's disease.

Keratitis

When the cornea is damaged, such as after a foreign body has penetrated the tissue, bacteria or fungi can pass easily into its deeper layers, causing a deep infection and inflammation. This condition may erode the cornea and create painful corneal ulcers.

Conjunctivitis

This term describes a group of inflammatory and often contagious diseases of the conjunctiva, the protective membrane that lines the eyelids and covers exposed areas of the sclera. These diseases can be caused by a bacterial or viral infection, drug allergy, environmental irritants, or a contact lens product.

Pterygia

A pterygium is a fleshy growth that usually starts in one corner of the eye and grows inward toward the cornea. Eventually, the pterygium will grow onto the cornea. Once that occurs, the pterygium dramatically obscures vision by inducing irregular astigmatism. By interfering with the visual axis, a pterygium can possibly lead to loss of eyesight in the affected eye if left untreated. Pterygia are caused by accumulated exposore to ultraviolet light (sunlight) over many years. Harsh conditions such as heat, dryness, wind, dust, smoke, and other environmental irritants can aggravate the condition.

Pingueculae

A pinguecula is a soft yellowish patch of tissue growing on the sclera just beyond the iris. Typically, pingueculae are located toward the corners of the eye at the 3 or 9 o'clock position. They are usually harmless, but can be precursors of pterygia. Like pterygia, pingueculae may be caused or aggravated by harsh environmental conditions.

Ocular Herpes

Herpes of the eye is a recurrent viral infection that affects about 400,000 Americans with herpes. Although ocular herpes can result from the sexually transmitted herpes simplex II virus, it is usually caused by herpes simplex virus I (HSV I), the virus responsible for cold sores. Ocular herpes may also be caused by the herpes zoster virus, the virus that causes chicken pox. The usual shingles rash caused by herpes zoster can spread from an involved area of the forehead or cheek to the upper or lower eyelids. Shingles may cause redness of the conjunctiva or small scratches on the cornea. The corneal scratches increase the risk of bacterial infection deeper within the eye, involving the uveal structures, retina, or optic nerve. Repeated or severe episodes of herpes zoster infection are associated with other eye conditions, including glaucoma, scarring within the eye, and cataract formation.
   

Ocular Adnexa Disorders

Ectropion

Ectropion is a condition of the lower eyelid in which the eyelid droops and turns outward. Aging, eyelid burns, or skin disease may cause this problem. Ectropion causes dryness of the eyes, excessive tearing, redness, and sensitivity to light and wind.

Entropion

Entropion or inward turning of the eyelid also occurs commonly as a result of aging. Infection and scarring inside the eyelid are other causes of entropion. When the eyelid turns inward, the eyelashes and skin rub against the eye, making it red, irritated, and sensitive to light and wind. If entropion is not treated, an eye ulcer may form.

Trichiasis

Trichiasis is a condition in which eyelashes are ingrown or misdirected, causing recurrent corneal irritation. Although seemingly a minor disorder, the condition can scratch the cornea and promote corneal infections.

Dacryostenosis

Blocked tear duct (dacryostenosis) occurs when the normal drainage system that allows tears to flow from the eyes into the nasal cavity is blocked or interrupted. This is a common condition in infants. It occurs when a membrane at the lower end of the drainage system fails to break properly during birth. In adults, blocked tear duct is uncommon and may have multiple causes. The main symptom of a fluid-filled tear duct due to a blockage is a tight, blue-gray swelling to the inside and below the lower eyelid.

Dry Eyes

If the lacrimal gland fails to produce enough tears to properly wet the eye, the surface of the eye becomes dry. An eye that is too dry typically burns and stings.

Strabismus

Strabismus is a visual defect in which the eyes are misaligned and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward, or downward. Strabismus is caused by the unequal tension and/or size of one or more of the six muscles that surround the eye and control its movement. About 4% of all children in the United States have some form of strabismus. The two most common types of strabismus are esotropia, i.e., inward turning of the eyes, and exotropia, i.e., outward turning of the eyes. Surgery is done to tighten, relax, or reposition the affected extraocular muscles.

Diagnostic Tools and Techniques
   

Corneal Topography

Corneal topography is a diagnostic procedure performed to detect and map irregularities in the corneal surface. A computer produces corneal images using colors to identify bumps and depressions, much like a topographic map of the earth depicts changes in land surface. The images aid in the diagnosis of keratoconus, astigmatism, and refractive errors.
   

Ocular Fundus Photography

The fundus, or inner lining, of the eye is photographed with specially designed cameras through the dilated pupil. Using color slide film, the painless procedure produces a sharp view of the retina, the retinal vasculature, and the optic nerve head (optic disc) from which the retinal vessels enter the eye.
   

Fluorescein Angiography

If fundus photography is performed after injection of the fluorescent contrast medium, sodium fluorescein, into an arm vein, the procedure is called fluorescein angiography. The dye travels quickly through the circulatory system and is photographed with black and white film as it travels through the eye. The normal progression of dye through the eye is interrupted by many diseases of the choroid, retina, and retinal vasculature. These studies are used to differentiate retinal diseases to determine appropriate treatment.
   

Indocyanine Green Chorioangiography (ICG)

ICG is a digital procedure which images the network of blood vessels in the choroid layer of the posterior eye. The injected indocyanine dye "fluoresces" in the infrared spectrum so that when imaged, the choroid becomes visible through pigmentation, fluid, or blood in the back of the eye. The procedure is helpful in detecting new obstructing vessels in ARMD.
   

Electroretinography (ERG)

This test measures the tiny electrical voltages produced by the rod and cone cells in the retina. Small electrodes placed around the patient's eye record these micro-voltages under various lighting conditions. The differences in voltages are analyzed to differentiate rod cell diseases from cone diseases. The ERG is performed in a specially shielded room called a Faraday's cage. It is commonly known as a copper room because the walls, ceiling, and floor are covered with copper sheeting to reduce electrical interference from generators and electric motors.
   

Slitlamp Biomicrography

A slitlamp illuminates the eye with a narrow beam of light as the eye is viewed through a horizontally mounted microscope. The cornea, anterior chamber angle, lens, vitreous, and retina can be visualized. The slitlamp serves as a delivery system for many types of ophthalmic lasers and accommodates various diagnostic attachments. Cameras can be mounted on the slitlamp for high-magnification photography. Removal of foreign bodies, sutures, or eyelashes is also frequently performed under slitlamp illumination.

Surgical Procedures
   

Retinal and Vitreous Procedures

Scleral Buckle Surgery

This procedure is the most common treatment for retinal detachments. The surgeon sutures a tiny piece of sponge or a length of silicon plastic to the outside of the sclera. This "buckle" effectively pushes the wall of the eye inward, placing it in closer proximity to the separated retinal tissue and allowing the retinal tissue to re-attach itself to the interior wall of the eye.

Laser Retinopexy

This procedure may be performed multiple times as a preventative measure against retinal detachment. The surgeon employs a special mirrored contact lens to view the retinal tear and direct the laser. An argon laser is then aimed circumferentially around the retinal tear. A minimum of two rows of coagulation are generally used to seal the tear. The resultant adhesions prevent seepage of fluid through the break and under the retina.

Retinal Cryopexy

This procedure achieves the same results as laser retinopexy with the use of a cryoprobe to freeze the retinal tear and prevent detachment.

Laser Therapy for ROP

Infants with severe vision-threatening cases of ROP may be treated with this type of laser therapy. A laser light beam is aimed at the retina through the eye's pupil by the surgeon. Hundreds of small laser treatment spots are placed to burn off some of the retina where the abnormal blood vessels have not grown. In order to save central vision, the part of the retina responsible for peripheral vision is destroyed.

Cryotherapy

Cryotherapy may be performed for severe cases of retinopathy of prematurity. A cold probe is applied repeatedly to the surface of the eye to freeze through the outside wall of the eyeball into the retina. The cold temperature destroys a part of the retina where the abnormal blood vessels have not grown. The therapy stops further retinal scarring and saves central vision.

Pneumatic Retinopexy

In this procedure the surgeon injects a gas bubble inside the vitreous cavity. The bubble pushes the retina against the wall of the eye, allowing retinal tears to seal against the eye wall. Gases often used for this procedure include perfluoropropane (C₃F₈) or sulfur hexafluoride (SF₆).

Vitrectomy

This procedure is another surgical option for the repair of retinal detachments. During this procedure, the vitreous is carefully removed from the eye with a fine needle, and then air or gas is injected into the cavity as in a pneumatic retinopexy. After surgery, the gases are gradually replaced by natural fluids produced inside the eye. Vitrectomy is also used to treat proliferative diabetic retinopathy in patients with a large amount of bleeding into the vitreous. If done for diabetic disease, however, the vitreous is replaced by a saline solution.

Laser Photocoagulation

Diabetic retinopathy is commonly treated with photocoagulation. In this kind of surgery, short spots of the laser's beam are directed at the retina to seal leaking blood vessels. The laser beam spots can also be scattered through the sides of the retina to reduce abnormal blood vessel growth (neovascularization) and help seal the retina to the back of the eye. The laser treatments often improve vision, but more significantly, they are effective in preventing further deterioration of vision.
   

Uveal Tract Procedures

Paracentesis

This procedure, also called an anterior chamber tap, may be done as either a diagnostic or therapeutic procedure. The surgeon aspirates aqueous humor from between the iris and the cornea with a needle inserted at the corneal-scleral junction (limbus). If hyphema is present, blood may also be aspirated from the anterior chamber. A saline flush may be done during the procedure to facilitate blood removal.

Adhesiolysis

In order to release the adhesions that sometimes occur following recurrent bouts of uveitis, the surgeon makes a small incision at the limbus to access the anterior segment. Adhesions are then severed, releasing the iris from surrounding structures. In anterior adhesiolysis, the surgeon severs adhesions between the iris and the cornea. In posterior adhesiolysis, adhesions between the iris and lens capsule or vitreous body are severed. The adhesive strands fall out of the visual field; removal of the adhesive remnants is not necessary.
   

Corneal and Conjunctival Procedures

Epikeratophakia

Epikeratophakia was originally developed to improve refraction for cataract patients who were intolerant of an intraocular lens implant, contact lens, or cataract glasses. It is now also used to treat some cases of keratoconus. The surgical term literally means "placing a lens on top of the cornea." In the procedure, the epithelium (the outermost layer of the cornea) is removed. Using a lathe, the surgeon then fashions a lens from two layers of donor cornea and sutures this new lens onto the patient’s cornea. The resulting change in corneal curvature improves the eye’s ability to focus.

Corneal Transplant Surgery (Keratoplasty)

Corneal transplants are the most successful of all transplant surgeries. Keratoplasty is performed for severe corneal dystrophies such as keratoconus. Under magnification of an operating microscope, the surgeon uses a "cookie cutter" type of instrument called a trephine to remove a button of tissue from a donor cornea. The trephine is then used to repeat this process in the patient’s cornea, removing defective tissue. The donor cornea is then sutured into place. Lamellar keratoplasty involves a partial thickness corneal excision, while penetrating keratoplasty requires full thickness corneal excision. The depth of tissue removed depends upon the type and location of the corneal disease being treated.

Pterygium Excision

Using a very precise scalpel and scleral scissors, the pterygium is separated from the normal corneal tissue lying beneath it. The remainder of the pterygium is then trimmed from the conjunctiva and the tissues are closed in layers with absorbable sutures.
   

Adnexal Procedures

Ectropion and Entropion Repairs

Several methods are used to correct ectropion and entropion. Because the repair techniques for ectropion and entropion are so similar, they are described together below:

• Suture: To repair ectropion, a suture is passed from the conjunctival side of the eyelid out through the front of the eyelid near the margin and then tied to a bolster of either cotton or plastic tubing. This suture tract creates scarring to evert the eyelid. Entropion suture repair is a similar procedure. A double-armed suture is passed from the inferior conjunctiva through the orbicularis muscle and out below the lid margin. The sutures create an inflammatory response with scarring that keeps the lid margin in place after the sutures are removed.
    
• Thermocauterization: To repair ectropion, scarring is created inside the eyelid by applying cautery to the conjunctiva. The scar tissue effectively pulls the eyelid back toward the globe. To repair entropion, thermocautery is applied to the outside of the eyelid parallel to the lid margin. The resulting scar formation everts the lid margin.
    
• Tarsal wedge resection: This procedure may be performed for either ectropion or entropion. The only difference in technique is the actual shape of the piece of tissue excised. In each case, the surgeon makes an incision under the eyelashes and removes a small wedge of tissue along the lid’s undersurface. To correct ectropion, the triangular wedge is positioned base up; for entropion correction, the wedge is positioned base down. The wound is then closed in layers, the skin is replaced over the surgical incision, and excess skin is removed.

Epilation

This is a minor procedure to remove the ingrowing eyelashes that occur with trichiasis. Using a biomicroscope for guidance, the surgeon removes the lashes with forceps. The surgeon may elect to simultaneously destroy the lash follicle with a laser, cryoprobe, or electrolysis.

Nasolacrimal Probing

This procedure is performed on infants and children whose tear ducts are blocked by a small membrane that prevents drainage of tears into the nose. The obstructive membranes is eliminated with passage of a small, firm wire through the tear duct into the nose.

Dacryocystorhinostomy (DCR)

DCR creates a new lacrimal drainage system from the lower eyelid into the nose. The procedure may be done via an external (transcutaneous) or internal (transnasal endoscopic) approach. In the external approach, a small skin incision is made midway between the bridge of the nose and the medial canthus of the eye. The incision is carried down to make a tiny opening in the nasal bone. The opening allows the tear sac to empty into the nasal passages, and reestablishing normal tear drainage. In the transnasal approach, an endoscope is placed in the nose for visualization and magnification of internal structures. The lacrimal duct is probed and the passage widened to improve drainage. If necessary, a Teflon stent is placed in the duct to maintain patency.

Conjunctivorhinostomy

When tear duct obstruction is beyond repair, direct fistulization of the conjunctiva to the nasal cavity is done to bypass the nonfunctional duct. This procedure may be done with or without implantation of a Pyrex glass Jones tube behind the medial canthus of the eye.

Punctum Plugs

If a patient suffers from very dry eyes, it may be beneficial to seal the opening of the tear duct (punctum) at the medial canthus to increase the amount of tears bathing the eye. The punctum may be effectively blocked by laser surgery, thermocautery, or ligation. Various plugs may also be inserted into the punctum. The plug may be a permanent silicone plug, such as the Freeman plug, or it may be a temporary collagen plug.

Strabismus Surgery

A number of procedures may be performed on the six extraocular muscles that control the eye’s position and movement. One or more muscles may be repaired in a single operative episode.

• Recession is performed to lengthen an eye muscle that is too tight. The surgeon isolates the muscle with a hook and severs its scleral attachment. The muscle is then repositioned (recessed) and reattached posterior to its original attachment on the sclera.
    
• Advancement strengthens a weak extraocular muscle. The surgeon excises a piece of the muscle to shorten it and then sutures the two ends together.
     
• Transposition is done in patients who have lost function in one of the extraocular muscles, usually the medial or lateral rectus muscle. The goal of transposition is to restore some of the eye’s movement in the weakened direction. The surgeon detaches healthy muscle from the sclera and resutures it adjacent to the paralyzed muscle. Sometimes the healthy muscle is split and only half of it is transposed next to the paralyzed muscle.
    
• Adjustable suture surgery uses a special suture technique to relax a tight extraocular muscle. After the muscle is detached from its original site on the sclera, the two ends of the cut muscle are loosely connected on two sides with long sutures. Then the sutures are tied and brought out through the overlying conjunctiva. Tension on the sutures is adjusted later when anesthesia no longer affects the globe’s position.
     
• Chemodenervation effectively paralyzes dysfunctional extraocular muscle tissue. After identifying the muscle either by direct surgical exposure or through the insertion of an electromyographic needle into the muscle, a small amount of botulin toxin is injected into the muscle belly. The procedure causes muscle paralysis within 24 to 48 hours. The paralysis lasts for up to 8 weeks.

Practice Makes Perfect!

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Read the operative report(s) on our procedure practice page. Then assign ICD-9-CM diagnosis and ICD-9-CM and CPT-4 procedure codes. Compare your answers with our coding recommendations. Good luck!

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