K. Bailey Freund,
Catherine B. Meyerle,
Lawrence A. Yannuzzi
Acute idiopathic maculopathy (AIM) is a rare disorder first described by Yannuzzi and associates in 1991. The nine patients in this original series experienced sudden unilateral visual loss secondary to an exudative maculopathy following a flu-like illness. The initial term was unilateral AIM, but further clinical experience revealed that this entity can present bilaterally. The preferred term today, therefore, is AIM.
AIM affects young adults with a mean age of 32 years (range 15-45 years) and has no sex predilection. It is uncommon, as demonstrated by a survey of the Macula Society, with most members of this organization seeing no more than one case per year. Of reported patients, the majority are of white race.
One reported patient was seen in the first trimester of pregnancy. Another patient was examined 4 weeks post partum. One patient was infected with human immunodeficiency virus but did not meet the clinical criteria for the acquired immunodeficiency syndrome. Of course, with small number of patients and without a matched control group, any description of epidemiologic features is preliminary.
AIM patients present with sudden onset of severe vision loss to the level of 20/200 or worse with central metamorphopsia or a central scotoma. A viral prodrome is typical and an association between AIM and coxsackie virus has been reported.4 We have seen an AIM patient with positive acute coxsackie titers (unpublished data).
On examination, patients have a quiet anterior segment. In the posterior pole, acutely, one sees a neurosensory retinal detachment with irregular margins overlying a smaller, grayish plaque at the level of the retinal pigment epithelium (RPE) (Fig. 150.1). Other signs of inflammation such as vitreous cell, papillitis, phlebitis, or intraretinal hemorrhage may also occur The mild vitreous cell is best appreciated with a contact lens. Papillitis (defined as disk hyperemia and fluorescein angiographic staining) has been reported in a few cases as a subtle obscuration of the disk margins. The retinal veins in these cases were somewhat prominent and tortuous from secondary obstructive change or a mild phlebitis. In one case, a relative afferent pupillary defect was noted (R Janigian and C Smith, unpublished data, 1995). Intraretinal hemorrhage may be mistaken for subretinal neovascularization by the less experienced observer Generally, the lesion is in the foveal center, but may present eccentrically. Patients with eccentric lesions have pre-senting visual acuities better than those typical for AIM at the level of 20/60 to 20/100. A subretinal exudate may be present in some cases. In one reported patient, the exudate had a peculiar fluffy, white appearance suggestive of inflammatory cells or debris.5 In a second patient, the exudate had a grayish, more solid appearance resembling subretinal fibrin seen in central serous chorioretinopathy.
FIGURE 150.1 (a) Color photograph shows an exudative detachment of the neurosensory retina, temporal to the center of the macula. There is a neurosensory retinal elevation overlying an irregular thickening at the level of RPE. Visual acuity is 20/60. (b) Late fluorescein angiogram reveals complete staining of the neurosensory retinal detachment. (c) Color photograph of the resolved state shows the characteristic atrophy of the RPE surrounding a clump of pigment epithelial hyperplasia, corresponding to the neurosensory retinal detachment and the pigment epithelial lesion respectively. Visual acuity is 20/20. (d) Color photograph of the fellow eye reveals a shallow alteration to the retina near the disk. There is an irregular, grayish thickening to the underlying RPE. (e) Fluorescein angiogram of the fellow eye shows staining of the acute lesion.
Whereas all the original cases were unilateral, three subsequent cases with bilateral involvement have been reported. In one case, macular involvement and acute loss of vision of the fellow eye occurred bilaterally within days of the original presentation. In the other two cases, the lesion in the fellow eye was eccentric to the macula, smaller in size, and asymptomatic.
The natural course of AIM for most patients is complete resolution of the exudative changes and near-complete restoration of the visual acuity (20/25 or better) within several weeks. Stigmata of the disease process persist after its resolution in the form of a bull's eye type lesion. Specifically, the pigment epithelial atrophic change corresponds to the previous neurosensory detachment and the irregular hyperpigmentation is reflective of antecedent pigment epithelial disturbance. In the cases with subretinal exudation, this material resolved in advance of the overlying neurosensory detachment and did not seem to influence the natural course of the disorder In the cases with papillitis, this resolved in tandem with the exudative macular changes.
To date, there have been no recurrent episodes in the cases studied. However, the long-term visual outcome may be affected by development of choroidal neovascularization (CNV) and disciform scarring secondary to the retinal pigment epithelial disturbance, which has occurred in two cases to date.
The fluorescein angiographic findings in the acute stage of AIM characteristically demonstrate early hyperfluorescence at the level of the RPE lesion. Late stage hyperfluorescence also occurs, corresponding to the combined subretinal staining external to the RPE and pooling within the overlying neurosensory retinal detachment. This late stage pattern is similar to the homogenous leakage seen beneath a serous pigment epithelial detachment. In the resolved state, a bull's eye pattern of central hypofluorescence surrounded by a ring of hyperfluorescence is observed corresponding to the typical RPE changes of the healed lesion. In the cases with papillitis, fluorescein angiography revealed disk staining in all three reported cases and mild perivenous staining in one instance.
Three cases were studied with indocyanine green angiography during the acute phase of their presentations. The studies were unremarkable except for some mild hypofluorescence corresponding to the exudative detachment, which was seen best in the late phase of the study. There was no late subretinal staining suggestive of CNV in any of these patients.
The differential diagnosis of AIM includes numerous degenerative, infiltrative, inflammatory, and infectious disorders, such as idiopathic CNV, serous detachment of the RPE, central serous chorioretinopathy, Harada's disease, serpiginous choroidopathy, posterior scleritis, acute posterior multifocal placoid pigment epitheliopathy (APMPPE), and secondary placoid syphilitic retinitis. A recent case report described an acute toxoplama retinitis masquerading as AIM,6 but the patient had satellite lesions and a marked retinal vasculitis not typical of AIM. Many patients with AIM are originally suspected of having central serous chorioretinopathy or idiopathic CNV. In fact, the authors have seen two AIM patients misdiagnosed with idiopathic CNV and treated with photodynamic therapy. These patients eventually did recover their central acuity to the level typical for AIM patients, but their visual recovery was delayed by several months. The typical flu-like illness accompanied by evidence of inflammation (vitreous cells, papillitis) helps to distinguish AIM from idiopathic CNV. Acute titers for coxsackie virus also help in making the diagnosis.
Indocyanine green angiography may be useful in distinguishing AIM from other entities. Some believe that AIM, in those patients without inflammation, may represent occult CNV that spontaneously infarcts and regresses. Indocyanine green angiography of AIM patients, however, has not demonstrated early vascular hyperfluorescence or late leakage consistent with CNV7 In addition, indocyanine green angiography can help differentiate AIM from central serous chorioretinopathy. Indocyanine green angiography of AIM patients does not demonstrate the mid-phase foci of choroidal hyperfluorescence suggestive of choroidal hyperpermeability that has been described in central serous chorioretinopathy.
A recent case report describes the optical coherence tomography (OCT) and multifocal electroretinogram (ERG) findings in a patient with AIM.8 The authors conclude that the acute OCT findings were consistent with thickening at the outer retina and RPE, and that these outer edematous changes resolved as visual acuity improved. Additionally, the reduced amplitudes in multifocal ERG were suggestive of outer retinal dysfunction as the cause of visual loss. These OCT and multifocal ERG findings indicative of outer retina and RPE pathology help exclude masquerading diseases that primarily involve inner retina.
Careful clinical biomicroscopy is essential to distinguish AIM from masquerading APMPPE. Although AIM shares several clinical and demographic characteristics with APMPPE, there are many features of AIM that exclude the diagnosis of APMPPE. These include the presence of a solitary macular lesion with a neurosensory retinal detachment, intraretinal hemorrhages, and early hyperfluorescence of an acute AIM lesion on fluorescein angiography. These features have not been reported in APMPPE.
Since this disorder is self-limited and most patients ultimately recover excellent visual acuity, it does not appear that treatment of the acute lesion is necessary. Perhaps of interest is that one of the patients in the original report who was treated with systemic corticosteroids ultimately developed milder pigmentary changes in the fovea than is typical.
AIM involves an inflammatory process of the RPE and, to a lesser degree, the optic nerve. An association with coxsackie virus has recently been reported in two patients. The authors have also seen an AIM patient with positive acute coxsackie titers (unpublished data). Of course, the clinical circumstances of each individual case should dictate what medical evaluation is appropriate, and any patients presenting atypically with, for example, exuberant inflammatory findings or lack of spontaneous resolution should undergo appropriate diagnostic testing.
AIM is a distinct entity with characteristic clinical and angiographic features. The frequent association with a flu-like illness, vitreous cells, and in some cases, papillitis and subretinal exudation is highly suggestive of an inflammatory disorder The recently reported association with coxsackie virus also suggests an inflammatory pathogenesis. Fortunately, the natural course of the disease is spontaneous, rapid resolution with recovery of excellent visual acuity. The recognition of this disorder is important to eliminate unnecessary and even potentially harmful treatment such as laser photocoagulation or photodynamic therapy of subretinal tissue misdiagnosed as CNV
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5. Fish RH, Territo C, Anand R: Pseudohypopyon in unilateral acute idiopathic maculopathy. Retina 1993; 13:26-28.
6. Lieb DF, Scott IU, Flynn HW, et al: Acute acquired toxoplasma retinitis may present similarly to unilateral acute idiopathic maculopathy. Am J Ophthalmol. 2004; 137:940-942.
7. Yannuzzi LA, Slakter JS, Sorenson JA, et al: Digital indocyanine green videoangiography and choroidal neovascularization. Retina 1992; 12:191-223.
8. Aggio F, Farah M, Meirellee R, et al: STRATUSOCT and multifocal ERG in unilateral acute idiopathic maculopathy. Graefes Arch Clin Exp Ophthalmol 2006; 244:510-516.