Pars plana vitrectomy for cases of medically refractory pseudophakic cystoid macular edema was recently confirmed to be useful; 24 consecutive eyes (23 with vitreous adhesions to anterior chamber structures and 1 eye with iris capture of the intraocular lens) showed significant (P < 0.0001) improvement in visual acuity (mean improvement of 4.7 Snellen lines) after the vitrectomy procedure.

Pars plana vitrectomy has proved to be ineffective, however, in a handful of cases of chronic CME after uncomplicated extracapsular extraction with ‘in the bag’ posterior chamber lens placement. Furthermore, this vitrectomy procedure should be considered only for pars planitis or chronic uveitis after less invasive approaches have failed. Specifically, cryotherapy should be performed for pars planitis, whereas systemic and subTenon’s injection therapies for chronic uveitis should be given a thorough trial before vitrectomy is considered for either condition. This is because potential side effects of the procedure, including retinal tears, retinal detachment, and rubeosis iridis, are significant.

Finally, cystoid macular edema should be considered more a medical problem than a surgical problem. The medical armamentarium has been enlarged significantly in recent years, and it is only after medical treatment has failed and definite indications for surgery (i.e. anterior segment distortion or vitreous traction on the macula) are present that invasive procedures should be contemplated.

COMPLICATIONS

The most common adverse reactions to oral anti-inflammatory medications are the following:

●Gastrointestinal discomfort (e.g. dyspepsia, constipation, nausea, vomiting, anorexia, flatulence);

●Headache;

●Somnolence;

●Dizziness;

●Tremor;

●Pruritus;

●Tinnitus;

●Palpitations.

To minimize side effects and to facilitate absorption into the serum, these drugs should be taken 30 minutes before meals.

Oral corticosteroids should not be given to patients with a history of peptic ulcers or osteoporosis. Before sub-Tenon’s injection of corticosteroids is performed, the patient should be tested for possible adverse response to steroids (e.g. elevated intraocular pressure) by topical applications because the periocular injection route most likely delivers the active ingredient to the eye for 1 month.

COMMENTS

The role of light toxicity in causing cystoid macular edema has been considered by many clinicians. Light delivered to the retina via intravitreal fiberoptic light sources during surgery has definitely been shown to be toxic to the retina; the coaxial light of an operating microscope delivered to the posterior segment of an aphakic eye is responsible for producing a pink scotoma during the first postoperative week. It is unclear what role light plays in the emergence of postoperative CME in cases of posterior vitrectomy.

REFERENCES

Fine BS, Brucker AJ: Macular edema and cystoid macular edema. Am J Ophthalmol 92:466–481, 1981.

Flach AJ: Cyclo-oxygenase inhibitors in ophthalmology. Therapeutic review. Surv Ophthalmol 36:259–284, 1992.

Fung WE, Vitrectomy-ACME Study Group: Vitrectomy for chronic aphakic cystoid macular edema: Results of a national, collaborative, prospective, randomized investigation. Ophthalmology 92:1102–1111, 1985.

Rossetti L, Bujtar E, Castoldi D, et al: Effectiveness of diclofenac eyedrops in reducing inflammation and the incidence of cystoid macular edema after cataract surgery. J Cataract Refract Surg 22(suppl 1):794–799, 1996.

Thach AB, Dugel PU, Flindall RJ, et al: A comparison of retrobulbar versus sub-Tenon’s corticosteroid therapy for cystoid macular edema refractory to topical medications. Ophthalmology 104:2003–2008, 1997.

307 EPIMACULAR PROLIFERATION

362.56

(Epiretinal Fibrosis, Macular Pucker, Cellophane Maculopathy, Preretinal Macular Fibrosis)

Alexander P. Hunyor, MB, BS, FRANZCO, FRACS

Sydney, Australia

Joseph E. Robertson, Jr., MD

Portland, Oregon

Epimacular proliferation is a descriptive term for the condition in which the macular region is distorted by the contraction of a fibrocellular epiretinal membrane (ERM) that has grown across the inner retinal surface. These membranes are the result of proliferation of, and collagen formation by, one or more of the following cell types: retinal pigment epithelial (RPE) cells, macrophages, fibrocytes, and astrocytes. The presence and proportion of these cells depend on the underlying cause, which may include a precipitating event such as retinal tears, inflammation, trauma, retinal vascular disease, vitreous hemorrhage, surgery including cryotherapy and photocoagulation, and idiopathic causes. Epimacular proliferation is a common condition, although it is frequently asymptomatic and does not require surgical management. Good surgical results are achieved with vitrectomy and ERM peeling in selected cases.

ETIOLOGY/INCIDENCE

Epimacular proliferation commonly occurs without an obvious precipitating cause and then is classified as idiopathic. Posterior vitreous detachment (PVD) has been noted in 75% to 93% of eyes with idiopathic epimacular proliferation. Partial or complete PVD may cause breaks in the internal limiting membrane (ILM), allowing migration and proliferation of fibrous astrocytes. Rupture of the ILM may actually be the cause of many cases of epimacular proliferation considered to be idiopathic. PVD may also result in retinal breaks, allowing the entry of RPE cells into the vitreous cavity.

The incidence varies according to the clinical classification scheme. Autopsy studies have shown ERM in 2% to 4% of eyes. Epidemiologic studies suggest a prevalence of 7% in persons over 50 years of age. The incidence increases with advancing age, as does the incidence of PVD.

307 ProliferationCHAPTER Epimacular •

Macula • 27 SECTION

COURSE/PROGNOSIS

The majority of ERMs involving the macula are nonprogressive and require no intervention. In one study, visual acuity remained 20/30 or better in 56% and 20/50 or better in 78% of affected eyes. Patients with significant visual symptoms due to ERM may be considered for surgery. Spontaneous separation of epiretinal membranes with resolution of visual symptoms is a well-documented but rare occurrence. The prevalence of ERM increases following uncomplicated cataract surgery, but these ERMs usually have little or no impact on vision.

DIAGNOSIS

Clinical signs and symptoms

Symptoms include visual distortion (metamorphopsia) and reduced/blurred vision. The diagnosis of epimacular proliferation is established on clinical grounds. Although the semiopaque nature of the ERM itself may contribute to visual loss, most symptoms appear to be secondary to distortion, edema, or localized detachment of the macula. The underlying cause should be sought in all cases; in apparently ‘idiopathic’ cases, an unrecognized retinal tear must be excluded.

●High-power biomicroscopy, preferably with a fundus contact lens, is required.

●Red-free light may facilitate the examination.

On examination, the appearance varies from thin and translucent ‘cellophane’ to thick opaque sheets. Retinal striae and vascular distortion are common (Figure 307.1a). PVD is usually present. Thin diaphanous ERMs are more typical of the idiopathic form. Denser ERMs are more common after retinal tear or detachment. These are probably a limited form of proliferative vitreoretinopathy. RPE cells predominate in these membranes.

Other findings include cystoid macular edema, localized traction detachment of the macula, ‘pseudoholes’ (round/ oval openings in the ERM, usually centrally), nerve fiber layer hemorrhages, and cotton-wool spots (due to axoplasmic stasis from ERM traction). ERMs are bilateral in 20% to 30% of patients.

Several clinical features of ERMs merit specific attention when surgical intervention is considered. Vessels underlying the membrane are usually tortuous, whereas vessels peripheral to the membrane generally appear to be straight and even narrow as they are dragged toward the epicenter or the point of maximal contraction. At least one edge of the membrane is often slightly elevated, and this should be noted because it may be the best location to initiate peeling of the membrane. Failure to find such an edge does not, however, preclude the patient from being an appropriate surgical candidate.

Laboratory findings

Optical coherence tomography (OCT — Figure 307.1b) provides additional information regarding the extent of the ERM, any persistent vitreous attachments, and macular thickness. Increased vascular permeability, induced by distortion of retinal vessels, results in significant extravascular leakage on fluorescein angiography in approximately 20% of cases. Angiography may also be useful in the assessment of any underlying retinal vascular disease that may limit the final visual prognosis. Rarely, a clinically unsuspected subretinal neovascular mem-

a

b

FIGURE 307.1. a) Color fundus photograph showing epiretinal membrane with vascular distortion and retinal striae. b) Optical coherence tomography (OCT) scan of epiretinal membrane with areas of separation (open arrow) and broad adherence (closed arrow) to retinal surface, with associated macular thickening.

brane may be detected on fluorescein angiography in a patient with epimacular proliferation.

TREATMENT

Medical

●There is no medical therapy for epimacular proliferation.

●Underlying conditions such as uveitis should be treated.

●Photocoagulation to areas of microvascular leakage due to traction from an epiretinal membrane should be avoided because it may result in further contraction of the membrane.

Surgical

Case selection

●Candidates include symptomatic patients with significant metamorphopsia or reduction in visual acuity (VA). No specific VA level is considered as a ‘cutoff,’ as patients with poorer VA but few/no symptoms often do not require surgery whereas patients with better VA but marked metamorphopsia may do so.

●Evaluate other causes of visual symptoms (e.g. cataract) and underlying conditions (e.g. retinal vascular disease).

●A visible ‘edge’ of the membrane is not a prerequisite for consideration of surgery.

308 CHAPTERHole Macular •

Macula • 27 SECTION

Antero-posterior or oblique vitreal traction exerted on a tightly adherent prefoveolar vitreous cortex is thought to initiate hole formation. Consequently, the risk of developing a macular hole after complete posterior vitreous separation is less than 1%. In contrast, patients with full-thickness macular holes whose asymptomatic fellow eyes demonstrate vitreal-foveal traction on OCT have more than a 40% chance of developing a macular hole in the second eye.

Most macular holes are isolated, but they may occur days to weeks after blunt trauma or in patients who have high myopia with a posterior staphyloma. Additional associations include: epiretinal membranes, cystoid macular edema, rhegmatogenous retinal detachment, YAG posterior capsulotomy, hypertensive retinopathy, diabetic retinopathy, Best’s disease, and adult vitelliform macular dystrophy.

COURSE/PROGNOSIS

The earliest sign of a macular hole is an abnormal vitreoretinal interface at the foveola. A stage 1A impending macular hole appears clinically as a yellow spot. Continued vitreal traction results in elevation of the foveolar retina (stage 1B impending), followed by a break in the photoreceptor layer at the umbo (stage 1B occult) with centrifugal displacement of the retinal photoreceptors, Müller cells, and xanthophyll. The clinical appearance is a small yellow ring. The patient often reports metamorphopsia, but visual acuity is usually nearly normal. Fifty percent of stage 1 holes spontaneously resolve.

A stage 2 hole is a 100–399 um full-thickness defect of the neurosensory retina. The prefoveolar vitreous cortex may separate, forming a pseudooperculum. If separation occurs at one edge of the hole, the defect appears eccentric. A true operculum is rare. Visual acuity ranges from 20/40 to 20/400.

A stage 3 hole is = 400 microns. Visual acuity is often 20/200 but (rarely) may be as good as 20/40. The vitreous cortex has separated from the central macula but remains attached to the optic nerve and often to the peripheral macula. The edges of the hole are elevated, with intraretinal cysts. A cuff of subretinal fluid may surround the hole. Nodular yellow opacities in the RPE may be found at its base.

Progression to a stage 4 hole occurs once the vitreous detaches from the optic nerve. A Weiss ring is present.

Left untreated, nearly all stage 2 holes will progress to stage 3 or 4 within 5 years. Spontaneous resolution of stage 2 or larger holes is rare. Tangential traction from epiretinal membranes may contribute to progressive enlargement.

DIAGNOSIS

The earliest visual complaint is usually metamorphopsia. Distortion may be apparent on the Amsler grid. As the hole enlarges, visual acuity declines. Untreated, vision usually stabilizes around 20/200.

Biomicroscopy has traditionally been used to diagnose and stage macular holes. Confirmatory tests may help solidify the diagnosis. While fluorescein angiography may demonstrate a hyperfluorescent window defect, the finding is non-specific. In the Watzke Allen test, most patients with a full-thickness macular hole will report a gap in a narrow vertical beam of light focused on the fovea through a condensing lens. In a similar test, a 50 micron laser aiming beam that is focused on the macular hole will not be seen if a full-thickness defect exists.

a

b

FIGURE 308.1. a) OCT of a stage 4 macular hole. Intraretinal cysts are present at the edges of the hole and a pseudooperculum is seen within the detached posterior hyaloid. Note that the hole is larger at its base than at the inner retinal surface. b) Stage 4 macular hole with a cuff of subretinal fluid and yellow deposits at its base. This patient also has macular drusen.

Optical coherence tomography (OCT) is the best ancillary test, as it can document vitreoretinal interface abnormalities not apparent biomicroscopically. It can also differentiate fullthickness macular holes from pseudoholes and lamellar holes. The basal diameter of the hole, which may correlate most with prognosis, can be measured more precisely with OCT (Figure 308.1).

Differential diagnosis

The differential diagnosis includes macular pseudoholes, lamellar holes, and cystoid macular edema.

TREATMENT

Prophylactic vitrectomy for stage 1 holes is usually not indicated. However, close observation is recommended, since 50% will progress to full-thickness defects, on average 4 months after the onset of symptoms. Occasionally traumatic macular holes, especially when small, may resolve without surgery.

Surgical management is recommended for holes graded stage 2 or higher. The overall anatomical success rate is >80% and

309 CHAPTERRetinopathy Solar •

Macula • 27 SECTION

would increase the likelihood of encountering an affected individual. Initial complaints may include a decrease in vision, central or paracentral scotoma, metamorphopsia, micropsia, chromatopsia, afterimage, and erythopsia. Both eyes may be involved but often asymmetrically, with the dominant eye more severely affected. Non-visual complaints include brow ache, headache, or both. On examination, visual acuity can vary widely, from 20/20 to 20/200. Amsler grid testing may reveal a small central or paracentral scotoma. Examination of the anterior segment is typically unremarkable, and the visual axis clear of any significant media opacity. Retinal exam can be normal or reveal varying degrees of retinal pigment epithelial (RPE) involvement. The typical presentation of acute solar retinopathy reveals a small yellow spot with a grayish border within the foveal area, though multiple spots may be evident. More subtle presentations may reveal an altered foveal light reflex or granular or punctuate irregularity to the RPE. In the more severe cases the yellow spot will change to a reddish spot that then develops into a foveal depression or 25–200-micron permanent lamellar defect.

Laboratory findings

Fluorescein angiography findings are often normal, though a small window defect may be noted. OCT findings can be normal or may show tiny hyper-reflective spots present in the inner retina. Amsler grid testing is useful in demonstrating the small central or paracentral scotoma of which patients often complain. Multifocal electroretinography has shown decreased amplitudes, with normal latencies.

Differential diagnosis

Other causes of lamellar depressions or holes include trauma and posterior vitreous detachment. Welding arc maculopathy is rare, and may require more prolonged exposure than solar retinopathy. This is in contrast to the keratitis that develops so commonly following brief exposure. The light flash or arc created by a high-voltage electrical short circuit may also produce similar retinal findings.

PROPHYLAXIS

Education is the most effective tool in helping prevent solar damage to the eye. Prior to a solar eclipse, a public awareness campaign about the risks of eclipse viewing and education about safe ways to view the event should occur. Eclipses should only be viewed indirectly using a pinhole projection system, in

which a pinhole is used to form the solar image on the inside of a cardboard box or other flat, non-reflective surface. The image thus formed can then be safely observed. It is important to emphasize that sunglasses do not provide protection for solar or eclipse viewing. In our everyday practices we will encounter patients who are at relatively higher risk for sun-related ocular injury, such as aphakic patients who should be fitted with eyewear that absorbs potentially damaging ultraviolet light. Modern-day intraocular lenses are designed to provide protection, but the conjunctiva and lids can still benefit from sunglasses and a brimmed hat.

TREATMENT

No effective treatment is known.

COMPLICATIONS

Many patients with solar retinopathy have a return of normal vision and resolution of symptoms over the weeks and months that follow. Some patients have a permanent reduction in vision and persistent metamorphopsia and or scotoma.

COMMENTS

Though patients with solar retinopathy are most frequently seen after a solar eclipse, this damage also occurs in the setting of purposeful sun gazing, which can cause serious and lasting retinal damage. There appears to be significant variation in susceptibility to solar retinopathy, with numerous risk factors suggested.

REFERENCES

Gass JDM: Stereoscopic atlas of macular diseases: diagnosis and treatment. 4th edn. St Louis, Mosby-Year Book, 1997.

Mainster MA: Solar eclipse safety. Ophthalmology 105:9–10, 1998.

Sadun AC, Sadun AA, Sadun LA: Solar retinopathy a biophysical analysis. Arch Ophthalmol 102:1510–1512, 1984.

Schatz P, Eriksson U, Andreasson S, et al: Multifocal electroretinography and optical coherence tomography in two patients with solar retinopathy. Acta. Ophthalmol. Scand 82:476–480, 2004.

Yannuzzi LA, Fisher YL, Krueger A, et al: Solar retinopathy: a photobiological and geophysical analysis. Trans Am Ophthalmol Soc 85:120–158, 1987.