Chapter 77 Surgical Management of Posterior Uveitis JANE C. WERNER Table Of Contents |
Patients with uveitis present a difficult array of diagnostic dilemmas
in which current knowledge and laboratory testing and systemic evaluation
often fail to reveal an underlying etiology (Table 1).1,2 Diagnosing an underlying etiology is desirable, and every attempt should
be made to do so; however, the ophthalmologist must still manage the
ocular disease whether or not the etiology is clear. This may contribute
to the difficulty in predicting the natural history of the disease
in a particular patient, as well as the uncertainty of selecting the
ideal medical regimen. The clinical courses of these patients vary widely
in regard to severity of visual loss, chronicity, number of inflammatory
episodes, response to anti-inflammatory treatment, and development
of secondary structural ocular alterations. Patients with disease
that involves posterior structures tend to develop difficult complications
that are marginally if at all responsive to medical treatments. These
include cystoid macular edema, loss of vitreous transparency with
cellular debris or hemorrhage, vitreous organization with bands or tractional
retinal detachment, and cyclitic membrane formation often with
hypotony leading to phthisis bulbi. Retinal vasculitis may result in
attenuation of vessels, nonperfusion of retinal tissue, retinal vascular
occlusions, retinal vascular or pars plana neovascularization,3,4 and vitreous hemorrhage. Exudative retinal detachment may occur. Underlying
inflammation of the retinal pigment epithelial or choroidal layers
can lead to permanent scarring, loss of photoreceptors, secondary subretinal
fibrosis, subretinal neovascularization, necrosis of the retina
and possible secondary detachment, and choroidal detachment. Optic
nerve swelling, ischemia, or inflammatory lesions of the nerve may cause
nerve fiber destruction and visual loss. Glaucoma secondary to inflammatory
debris, permanent angle alterations, iris bombé, or steroid
treatments can also compromise optic nerve function. Infective
agents may produce intraocular granulomas, abscess lesions, and proliferative
organization of the vitreous, or the wipeout syndrome associated
with nematode larvae. Involvement of anterior segment structures often
occurs in conjunction with these problems as a “spillover” effect; for
instance, the development of increased aqueous protein
seen clinically as flare, or the presence of cells in the anterior chamber, may
be secondary to inflammation primarily affecting another structure. Also, many
of the uveitic entities can be classified as panuveitis
with potential to cause complications in any part of the eye. Anterior
segment structural changes that complicate uveitic entities affecting
those structures, such as keratouveitis, keratitis, iritis, and
iridocyclitis, include band keratopathy, corneal scarring or perforation, anterior
synechiae, posterior synechiae, elevated intraocular pressure, and
cataract formation. One or more of these problems often must
be managed in patients with posterior uveitis.
TABLE 1. Systemic Conditions and Etiologies Associated with Uveitis Intermediate Uveitis and Vitritis
Retinal Vasculitis With or Without Retinitis
Choroiditis and Retinal Pigment Epitheliitis
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SURGICAL INTERVENTIONS FOR DIAGNOSIS |
The surgical decisions made in the management of patients with uveitis
can be understood, researched, and discussed in terms of the goal(s) of
the intervention. Standard ocular procedures such as anterior segment
paracentesis, pars plana vitrectomy, and vitreous biopsy by the pars
plana route are used to obtain intraocular fluids and specimens to diagnose
the etiology of the intraocular inflammation.5 This includes the recent development of endoretinal biopsy techniques6,7 and enucleation of a blind fellow eye in the clinical setting of sympathetic
ophthalmia or a destructive unrelenting suspected infectious process. The
concern for the possibility of systemic lymphoma presenting
as intraocular inflammation (vitritis or choroidal infiltrates) calls
for a diagnostic vitrectomy with cytologic examination of the specimen, which
is studied for cell surface markers.8,9 The group of masquerade syndromes (malignant tumors that produce an intraocular
inflammatory condition) may require a cytologic specimen to
confirm a malignancy. Fluid from eyes with suspected Toxocara canis infection can be analyzed with enzyme-linked immunoassay (ELISA) testing.10 Patients with suspected endophthalmitis routinely undergo vitrectomy or
vitreous tap for bacterial and fungal cultures and sensitivity and are
administered antimicrobial agents. The indications for diagnostic surgical
interventions in these patients are expanding. Research in immunologic
and microbiologic techniques, such as the polymerase chain reaction (PCR) to
detect viral DNA in intraocular tissues, is adding an
enormous amount of new information that can be tested for and discovered
in an intraocular specimen.11,12 Combined with serologic studies, clinically useful and diagnostic information
gained from these investigations is allowing for a better understanding
of the causes of intraocular inflammation and a rational approach
to prevention or treatment. Chorioretinal endobiopsy has been described in and recommended for those patients with sight-threatening chorioretinitis that is unrelenting and unresponsive to therapy. Usually, the agents selected for treatment are based on the clinical appearance and suspected etiologic cause of the posterior necrosis. Occasionally, an atypical appearance, an unusual clinical course, or an immune-altered host requires tissue inspection, cultures, and further tissue testing in an attempt to diagnose the problem more precisely. A rational therapy can be instituted based on a biopsy specimen. Internal pars plana vitrectomy approaches to this procedure have been described and referenced above. As shown in Figure 1, a standard three-port vitrectomy is used. If the attached retina is affected, such as in retinitis, a relatively avascular site 3 mm in size is chosen, if possible in the superior quadrants. Unimanual bipolar endodiathermy is applied to the full thickness of the chorioretinal layer. The specimen is removed as a button from the underlying sclera through a pars plana sclerotomy. Additional endolaser is placed around the edges of the biopsy site. After hemostasis is achieved with additional endodiathermy, an air-fluid exchange is done. The eye is then flushed with a long-acting, nonexpansile gas mixture.6 Immediate attention should be directed to processing the specimen. Every effort should be made to have the pathologist in the operating room to receive the specimen. |
SURGICAL INTERVENTIONS DIRECTED TO ANATOMIC ALTERATIONS OR COMPLICATIONS OF A UVEITIC PROCESS |
All of these distinct and, in many cases, irreversible anatomic alterations
are produced by complications of an inflammatory process. Specific
procedures are usually directed toward correcting a complication of
an intraocular inflammatory process. The inflammation should be medically
controlled to be as quiet as possible for as long as possible, such
as several months prior to surgery. The problems related to anterior
segment effects may require chelation of band keratopathy, penetrating
keratoplasty, breaking of synechiae, and glaucoma filtering surgery. Surgical
iridectomy is often recommended for iris bombé because
of closure of laser iridectomies by inflammatory debris or pigment. Formation of cataracts is often the result of a chronic inflammatory disturbance of the lens. Chronic use of corticosteroids adds its own cataractogenic influence. The result is a patient with cataract lens opacities that play a role in what is often decreased vision based on this and other problems. The discussion of isolated cataract removal is to follow. Cataracts in patients with posterior uveitis often exist with vitreous opacities, macular edema, or macular cellophane membranes or macular pucker. The combination of pars plana vitrectomy with cataract extraction not only clears the visual axis but may reduce the severity and incidence of recurrences of inflammation. Recent series in the literature support this. Each series has emphasized the need for preoperative control of inflammation by use of topical and periocular corticosteroids with several repeated injections if necessary, usually 2 to 3 weeks apart, and oral nonsteroidal anti-inflammatory medicines. The patient may need oral corticosteroids or immunosuppressive therapy. Drugs reported in the literature that are used in the preoperative control of inflammation include cyclophosphamide (2 mg/kg), azathioprine (2 mg/kg), chlorambucil (0.2 mg/kg), and cyclosporine (5 mg/kg). Retrospective case reviews also demonstrated case selection, where patients were not operated on if they had severe recurrent inflammation.13–23 Rationale for the decision to implant posterior chamber intraocular lenses continues to grow, and conditions in which this has been performed successfully continue to be defined by recent experience and publications. Care must be taken to access the stability of the capsular zonular strength. It has been reported that inflammatory destruction of the zonules may lead to intraoperative displacement during the placement or positioning of an implant, and that preoperative examination may detect crystalline lens subluxation.24 It is believed that complete removal of the lens cortex and placement of an all-polymethylmethacrylate posterior chamber lens in the bag may be factors in reducing postoperative inflammation. Phacoemulsification, planned extracapsular extraction, and ultrasonic fragmentation via the pars plana have all been successfully used to remove the lens in these patients. Surgeons have reported complications in uveitis patients even after technically ideal cataract surgery with or without posterior chamber lens implantation. Visual rehabilitation is limited by cystoid macular edema, pupillary membranes, dense capsular opacities, postoperative hemorrhage from abnormal iris vasculature, hypotony, and chronic postoperative inflammation. Aggressive medical control of the inflammatory process is repeatedly suggested as an adjunct to improved visual outcome. The underlying destructiveness of the inflammatory process and the natural history of the disease should be considered in selecting patients for cataract extraction and intraocular lens implantation. First, as previously mentioned, pars plana vitrectomy can be done in combination with cataract extraction, or it can be done to clear vitreous debris. Second, in several published studies, vitrectomy has been observed to lessen the frequency and severity of recurrences of inflammation. These studies have included patients with intermediate uveitis and chronic posterior uveitis.25–27 Third, patients with iris bombé and initially elevated intraocular pressure who do not respond adequately to medical and anti-inflammatory management may require mechanical clearing of the pupillary and retropupillary space. Lastly, advanced vitreoretinal surgical procedures may be needed to repair complex tractional detachments of the retina that may be combined with a rhegmatogenous component or an associated ciliary body detachment with hypotony. The patient who develops chronic progressive hypotony is usually in the end stage of their disease. When medical measures fail to increase intraocular pressure, the cause is attributed to failure of the ciliary body. These eyes may be stabilized for an extended period of time with pars plana vitrectomy and a complete fill of silicone oil. In patients with vitritis as a component of their uveitis, organization and fibrosis of the vitreous base area can occur. This often includes the pars plana area. Dense organization and neovascularization of the pars plana occur in pars planitis. Sclerotomy at the time of pars plana vitrectomy must be made with a fresh, sharp microvitreoretinal blade and must be large enough to accommodate the subsequent passage of other instruments. This is to avoid traction on the vitreous base (Fig. 2). Otherwise, a dialysis with subsequent retinal detachment will complicate the surgery. Cryotherapy of the sclerotomy sites at the conclusion of surgery may help to prevent postoperative retinal detachments from a break in this area. The combination of external cryotherapy of the pars plana and vitrectomy in pars planitis patients has been reported to be complicated by giant retinal tears presumably at the edge of the cryotherapy.27 Retinal detachment in eyes with uveitis may be due to an isolated rhegmatogenous mechanism or a combined traction-rhegmatogenous mechanism. Posterior vitreous separation caused by vitreous inflammation can lead to retinal breaks and cause retinal detachment. Often the retina can be reattached with a scleral buckling procedure. If there is significant vitreous opacity, vitrectomy and scleral buckling may be required to reattach the retina. Fibrous or even fibrovascular proliferation associated with uveitis can cause or complicate retinal detachment. Pre-existing epiretinal membranes present before retinal detachment can lead to fixed folds and a picture of proliferative vitreoretinopathy after retinal detachment, whether retinal breaks and retinal detachment are a result of the epiretinal membranes or not. In addition, there appears to be a high propensity for eyes with retinal detachment associated with uveitis to develop fibrous epiretinal membrane proliferation and proliferative vitreoretinopathy after initially successful retinal reattachment. Factors thought to be important in the development of proliferative vitreoretinopathy, such as breakdown of the blood-ocular barrier, influx of inflammatory cells and macrophages, and a high level of growth factors, are often present. These eyes may require advanced vitreoretinal techniques, such as lensectomy, epiretinal or subretinal membrane removal, retinotomy or retinectomy, use of perfluorocarbon liquids, laser endophotocoagulation, and intraocular gas or silicone oil tamponade. The approach using pars plana vitrectomy techniques allows for clearing lenticular opacities, pupillary membranes, cyclitic membranes, retrolental proliferation, tractional epiretinal membranes, and neovascular proliferative tissue. Techniques of segmentation and stripping of membranes overlying the peripheral retina, ora serrata, and ciliary body are enhanced by the intraoperative techniques of scleral indentation. Removal of the persistent traction prevents ciliary body detachment, hypotony, and potential phthisis bulbi. If neovascular tissue is present, endophotocoagulation is applied during surgery to reduce its growth and activity. Eyes with uveitis are particularly likely to develop anterior retinal displacement (formerly called anterior loop traction). Anterior retinal displacement can precede posterior retinal detachment in eyes with cyclitic membranes associated with chronic uveitis. Fibrovascular proliferation from the ciliary body or anterior retina can lead to traction detachment of the anterior retina and ciliary body. Eyes with intermediate uveitis sometimes develop fibrovascular proliferation in the vitreous base area usually located inferiorly. These so-called pars plana exudates may become extensive and cause anterior retinal displacement and traction retinal detachment. When uveitis is associated with general retinal detachment, a high and anterior scleral buckle will often adequately relieve traction; however, when severe proliferative vitreoretinopathy is present, retinotomy or retinectomy may be necessary to adequately relieve traction. With the use of advanced techniques, the retina can usually be reattached in eyes with uveitis and severe anterior retinal displacement, but there is a high incidence of recurrent retinal detachment and postoperative hypotony, which reduces the overall prognosis as compared with similar cases in eyes without uveitis. This may be due to ongoing inflammation, which contributes to reproliferation of membranes and traction on the retina and ciliary body. Systemic and periocular steroids are necessary to control perioperative inflammation. Preoperative steroids are recommended to reduce inflammation before surgery, and steroids should be continued as necessary postoperatively. External cryotherapy or diathermy has been described specifically to ablate the neovascular complications of pars planitis.28–31 In patients with pars planitis, resistance to control of the inflammation with steroid treatment is often associated with the presence of vascular anomalies in the area of the exudates at the pars plana. The course of the inflammation, and sometimes secondary vitreous hemorrhage, is stabilized after this treatment. Also, removal of vitreous debris with vitrectomy has been combined with this approach. |
OCULAR CONDITIONS REQUIRING SURGERY IN PATIENTS WITH UVEITIS |
Control of inflammation in the perioperative period requires special attention
in these patients. The stimulation of inflammation presumably
by the surgical procedure may reactivate the underlying uveitis and precipitate
a flare-up that will jeopardize the outcome and may be very
difficult to quiet with corticosteroids. With elective procedures, the eye should be quiet without medications for several months. Often it is not possible to clear every cell from the anterior chamber or vitreous, and if stopping, for example, low-dose steroid drops is not successful, then the patient should be treated with systemic corticosteroids starting one day before surgery. The usual dose is around 1 mg/kg/day, to be modified for the individual patient. This can be given intravenously during the surgical procedure and daily thereafter as an oral dose, tapering as rapidly as the eye tolerates and demonstrates a reduction in inflammation. Periocular depo steroid can be placed at the closing of the surgery if the patient does not exhibit a steroid-related intraocular pressure rise. Postoperative fibrin can be managed in severe cases with tissue plasminogen activator, as described in other conditions that manifest an intense inflammatory reaction related to the breakdown of the blood-ocular barrier, such as diabetic proliferative disease. If the inflammation rebounds several days after surgery, a prolonged course of corticosteroids may be required. The potential for hazy media is greater in uveitis patients, making photocoagulation or cryopexy of a retinal tear technically more difficult. Overtreatment with these modalities should be avoided. This applies to surgery for rhegmatogenous retinal detachment, because an inflamed uvea may predispose the eye to the complications of choroidal hemorrhage. Postoperative inflammation may be greater and needs aggressive medical treatment. |