Neuro-Ophthalmology, 32:200–202, 2008Copyright ©c Informa Healthcare USA, Inc.ISSN: 0165-8107DOI: 10.1080/01658100802274895

PHOTO ESSAY

Infrared Fundus Photography in a Caseof Acute Macular Neuroretinopathy

Matthieu P. A. RobertNeuro-OphthalmologyDepartment, Moorfields EyeHospital, London, UnitedKingdom

Andrew R. WebsterMedical Retina Department,Moorfields Eye Hospital, London,United Kingdom

Gordon T. PlantNeuro-OphthalmologyDepartment, Moorfields EyeHospital, London, UnitedKingdom

ABSTRACT A 19-year-old female presented with a 4-month history of bilateral,para-central flickering lights, stable over that time after a sudden onset. Exam-ination revealed isolated, bilateral, reproducible and incongruent para-centralscotomata. Conventional imaging of the retina and OCT of the macula werenot conclusive. Infrared imaging of the fundi showed typical lesions of acutemacular neuroretinopathy. The unique physical properties of the near infraredwaves recently widened the field of retinal imaging and are of particular interestin the diagnosis of deep retinal layers.

KEYWORDS Acute macular neuroretinopathy (AMN); infrared imaging; fundus; retina

A 19-year-old female was referred to the neuro-ophthalmology departmentwith a 4-month history of “bilateral flashing lights” with preserved visual func-tion and normal ophthalmological examination. The onset was sudden, over 3hours, a few days into a flu-like illness, followed by symptomatic stability. Thesymptoms were bilateral flickering green lights, persisting despite eye closure.The phosphenes were localized within para-central temporal rounded patches,which the patient drew on an Amsler grid. Visual acuity and color vision werepreserved, visual field examination (confrontation to red pin and Humphrey10-2) showed bilateral incongruent para-central scotomata corresponding to thepreviously mentioned patches (Fig. 1a, b). Slit lamp examination and colorphotographs of the fundi indeed showed no abnormality except an abnormalfoveal reflection. Green filters photographs (Fig. 1c,d)ed localized para-fovealareas of mild cone dysfunction. Infrared photographs taken with a scanninglaser ophthalmoscope (SLO) demonstrated dark, petal-like, sharp oval areas inthe macular region, pointing towards the fovea which corresponded remarkablyclosely with the scotomata, typical of acute macular neuroretinopathy (AMN)lesions (Fig. 1e,f).

AMN was first described in 1975.1 This rare condition usually occurs infemales in their reproductive years, most often into an influenza-like syndrome.It may be uni- or bilateral and clinically presents with a sudden onset of multipleincongruent paracentral scotomata, visual acuity being either normal or slightlydecreased.

Accepted 3 May 2008.

Address correspondence to Gordon T.Plant, Moorfields Eye Hospital, 162City Road, London EC1V 2PD, UnitedKingdom. E-mail: gordon@plant.globalnet.co.uk

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FIGURE 1

Classically, fundus examination is abnormal andshows either typical reddish-brown, petal-like macularlesions pointing towards the fovea, or more rarely mul-tiple small red macular spots. Fundus lesions preciselycorrespond to the defects seen on formal visual fields asin our case. Fluorescein angiography is usually normal,the pattern-evoked electroretinogram (pERG) may bedisturbed at an early stage.2,3 However, at certain stagesin the development of the disorder both fundus ex-amination and pERG may be unremarkable4 as in thepresent case. Infrared photography, mfERG and 3-DOCT may hence be of particular interest and indicate

that the pathological process is deeper located than firstthought, most likely in the photoreceptor outer seg-ment layer.4–10

Spectral filters with various transmission proper-ties (blue, green, red) have long been used in fundusphotography.11 In addition to the properties due to thenature of the color used, the longer the wavelength,the higher the reflectance and the deeper the light pen-etration into the retina.12 Near infrared waves havetherefore a better fundus reflectance than any wavefrom the visible spectrum and penetrate deeply intothe choroid.12 Many disappointing attempts had been

201 Infrared Fundus Photography

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made to use them in ophthalmology,11 but SLO tech-nology can now provide excellent contrast.13 Such pho-tographs are of particular interest in the case of low con-trast lesions located below the penetration limit of themedium wavelength (green) light (in the extreme outerlayers of the retina or the choroid) and should thereforegreatly improve our knowledge of the pathophysiologyof such disorders.

Furthermore, difficult diagnostic problems can besolved, as was the case here. Figure 1: left (a) and right(b) Humphrey 10.2 visual fields (no fixation losses, falsepositive errors: 2% and 0%, false negative errors: 10%and 0%, foveal threshold: 40 and 39 dB); left (c) andright (d) upside-down green filter fundus photographs;left (e) and right (f) upside-down infrared fundus pho-tographs. N.B. The visual fields are represented con-ventionally; therefore in order to get a correspondencewith the fields, the fundus photographs are representedon the left for the left eye and vice-versa, with the upperretina down and vice-versa.

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[10] Monson BK, Greenberg PB, Greenberg E, Fujimoto JG, SrinivasanVJ, Duker JS. High-speed, ultra-high-resolution optical coherencetomography of acute macular neuroretinopathy. Br J Ophthalmol.2007;91:119–120.

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[12] Elsner AE, Burns SA, Weiter JJ, Delori FC. Infrared imaging ofsub-retinal structures in the human ocular fundus. Vision Res.1996;36:191–205.

[13] Webb RH, Delori FC. How we see the retina. In Marshall J ed. LaserTechnology in Ophthalmology. Amsterdam: Kugler & Ghedini Pub-lications; 1988.3–14.

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