27 Macula

ing CNV that is obscured by hemorrhage or pigment epithelial detachment, although no randomized, controlled clinical trials support their use in determination of treatment.

●Optical coherence tomography (OCT) has become a useful adjunct to fluorescein angiography in determining the amount of subretinal and intraretinal fluid leakage associated with CNV.

PROPHYLAXIS

●Smoking cessation and control of hypertension have been suggested by population-based studies as possible ways of modifying risk for advanced AMD.

●Daily nutritional supplement consisting of vitamin C,

500 mg, vitamin E, 400 IU, beta carotene, 15 mg, zinc, 80 mg, as zinc oxide and copper, 2 mg (commercially available as Preservision AREDS Formula, Bausch and Lomb one capsule twice a day), has been shown to reduce the risk of advanced AMD in patients with high risk features (large drusen, non-central geographic atrophy, or advanced AMD in contralateral eye).

solution in the conjunctival fornix prior to injection with a 30 gauge needle at the pars plana. In current clinical practice, injections are commonly delivered on a monthly basis , as had been used in most clinical trials. However, many of the treating physicians employ treatment on an ‘as needed’ basis. This involves close follow-up of the patient (usually at monthly intervals initially) with optical coherence tomography along with careful examination to determine if repeat injections are necessary.

Prior to the general availability of ranibizumab many physicians investigated the use of intravitreal treatment with bevacizumab (Avastin, Genentech), a humanized antibody against VEGF-A developed for treating colon cancer . Shortterm observations involving many patients treated with intravitreal bevacizumab yielded favorable results which were considered by many to be comparable to those achieved with ranibizumab. While lacking the long-term evidence for efficacy and safety established for its cousin ranibizumab, the shortterm favourable results and the much reduced cost of bevacizumab has resulted in its current widespread usage. A national head-to-head trial with bevacizumab and ranibizumab is planned.

Pegaptanib sodium is an aptamer specific for certain forms of VEGF. It was the first anti-angiogenic agent to be approved

thin, and omega-3 fatty acids, show some promise but have not yet been rigorously studied.

●Clinical trials are under way to determine whether an antiangiogenic agent could be effective in reducing the rate of advanced AMD in high-risk patients.

TREATMENT

No treatment is currently available for the non-neovascular form of AMD, other than the preventive precautions mentioned above. Several treatments are directed towards inhibiting and/ or destroying choroidal neovascularization.

Systemic

No systemic treatment is available for AMD at this time, although systemically administered anti-angiogenic agents are being evaluated.

Ocular

The introduction of antiangiogenic agents has revolutionized the treatment of neovascular AMD. Ranibizumab (Lucentis, Genentech), is a humanized antibody fragment against vascular endothelial growth factor-A (VEGF-A) which has been studied in randomized clinical trials. Regardless of lesion characteristics (e.g. occult vs classic), patients treated with an intravitreal injection of ranibizumab every four weeks over a period

have shown to be more effective, this drug has a very limited role in treatment of AMD at this time.

Photodynamic therapy (PDT) takes advantage of verteporfin (Visudyne, Novartis), light-sensitizing dye with an affinity for the neovascular tissue to selectively destroy neovascular tissue. This was the first available treatment for subfoveal choroidal neovascularization that did not result in immediate vision loss. While this treatment was superior to observation in predominantly classic lesions, and smaller occult and minimally classic lesions. PDT is seldom indicated as the first line treatment today because of the availability of antiangiogenic agents. However, its use in combination with these agents is currently being investigated, and PDT alone or in combination with intravitreal steroids continues to have a limited role in selected cases.

The Macular Photocoagulation Study (MPS) demonstrated in a randomized controlled clinical trial that laser photocoagulation for patients with neovascular AMD resulted in better visual acuity than observation alone. With the subsequent development and use of newer and more effective treatments, photocoagulation is seldom used in clinical practice today.

Surgical

The Submacular Surgery Trial examined the role of vitrectomy and submacular surgery in the treatment of CNV in AMD. In patients with hemorrhagic or subfoveal choroidal neovascular-

ization due to AMD, vitrectomy and removal of the membrane did not result in improved outcome.

Macular translocation has been reported to be of benefit in well-selected patients, although complications leading to complete blindness can occur in both the limited and ‘total 360’ renditions of the surgery.

COMMENTS

Low vision aids can allow patients to read, write, and even drive. A variety of magnification devices and telescopic devices are available. A careful evaluation by a low vision specialist can significantly improve patients’ functioning and their quality of life.

REFERENCES

AREDS: A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss. Report no. 8. Arch Ophthalmol 119:1417–1436, 2001.

Gragoudas ES, Adamis AP, Cunningham ET, Jr, et al: Pegaptanib for neovascular age-related macular degeneration. N Engl J Med 351:2805– 2816, 2004.

Guidelines for using verteporfin (visudyne) in photodynamic therapy to treat choroidal neovascularization due to age-related macular degeneration and other causes. Retina 22:6–18, 2002.

Hawkins BS, Bressler NM, Miskala PH, et al: Surgery for subfoveal choroidal neovascularization in age-related macular degeneration: ophthalmic findings: SST report no. 11. Ophthalmology 111:1967–1980, 2004.

Jonas JB, Akkoyun I, Budde WM, et al: Intravitreal reinjection of triamcinolone for exudative age-related macular degeneration. Arch Ophthalmol 122:218–222, 2004.

Macular Photocoagulation Study Group: Laser photocoagulation of subfoveal neovascular lesions of age-related macular degeneration. Updated findings from two clinical trials. Arch Ophthalmol 111:1200–1209, 1993.

Toth CA, Freedman SF: Macular translocation with 360-degree peripheral retinectomy impact of technique and surgical experience on visual outcomes. Retina 21:293–303, 2001.

retinal vascular disease and retinal detachments because the outer third of the retina derives its nourishment from the choriocapillaris.

Retinitis pigmentosa and perifoveal telangiectasia also are involved with disturbances or shunts in the retinal circulation, whereas choroidal tumors have been linked either to occlusion of retinal capillaries secondary to vascular endothelial cell hypertrophy or edema, or to cyst formation through expansion of extracellular spaces by serous exudates within the inner plexiform and inner nuclear layers.

COURSE/PROGNOSIS

By far the most common situation associated with CME is cataract surgery, particularly intracapsular procedures; the surgical trauma to the anterior segment is thought to stimulate the production of prostaglandins or retard their resorption within the eye. Various investigators have found CME to occur after 40% to 60% of intracapsular cataract extractions; extracapsular surgeries result in CME in only approximately 10% of cases.

The position of an intraocular lens also can contribute to CME. Lenses suspended in the pupil have the worst prognosis, followed by anterior chamber lenses. Posterior chamber lenses implanted ‘in the bag’ have the lowest incidence of CME. Fortunately, the condition resolves spontaneously in 3 to 6 months in the majority of patients; however, if the anterior hyaloid face is disturbed or if formed vitreous is incarcerated in the corneoscleral wound, the condition may become chronic.

Diabetic retinopathy is the second most common condition associated with CME. It is largely seen in patients with adultonset (after age 30) diabetes whose disease is of 10 years’ duration or more. Concomitant hypertension or arteriosclerosis makes the presence of CME more likely as a complication of diabetic retinopathy.

Certain antiglaucoma medications, such as latanoprost, have been associated with an increased incidence of cystoid macular edema and anterior uveitis. Recent studies estimate that between 1% and 5% of patients taking the drug may develop anterior uveitis, CME, or both.

306 CYSTOID MACULAR EDEMA

362.53

(Cystoid Maculopathy, Irvine–Gass

Syndrome)

Wayne E. Fung, MD

San Francisco, California

ETIOLOGY

Cystoid macular edema (CME) is a common cause of decreased central vision, resulting from fluid accumulation in intraretinal spaces in the macular region.

Two possible mechanisms have been postulated to explain the occurrence of CME in such a diverse array of conditions: inflammation and anoxia. The inflammatory theory may account for CME associated with cataract surgery, postscleral buckling procedures, and chronic uveitis, including pars planitis. The vascular occlusion mechanism, on the other hand, readily explains the conditions associated with obvious

DIAGNOSIS

CME is considered a sign of an underlying ocular and/or systemic disease process and not an entity in itself. It is associated with many clinical situations, including the following:

●Cataract surgery;

●Diabetic retinopathy;

●Exudative age-related maculopathy (with serous macular detachment);

●Tributary or central retinal vein occlusions;

●Scleralbuckling procedures;

●Chronic uveitis, pars planitis;

●Collagen-vascular disease;

●Aphakia with topical antiglaucoma epinephrine compounds;

●Tumors of the choroid (melanoma, capillary hemangioma);

●Diabetic traction detachments;

●Retinitis pigmentosa;

●Epiretinal membranes;

●Drug reactions;

●Toxic conditions (i.e. nicotinic acid intoxication);

●Perifoveal retinal telangiectasia.