BritishJournal ofOphthalmology, 1990,74,370-372

CASE REPORTS

Refsum's disease: electron microscopy of an irisbiopsy

Andrew D Dick, Jonathan Jagger, Alison C E McCartney

AbstractRefsum's disease (phytanic acid storagedisease) results in an accumulation of lipid as aresult ofan absence of mitochondrial hydroxy-lation of phytanic acid. We describe a pre-viously unrecorded electron microscopic studyof lipid deposition in the iris pigment epithe-lium of a patient with Refsum's disease, andlipid was present in other sites within the iris.

Department ofOphthalmology,University CollegeHospital, LondonA D Dick

Department ofOphthalmology, RoyalFree Hospital, LondonJ Jagger

Institute ofOphthalmology, LondonA C E McCartneyCorrespondence to:Dr A D Dick, Department ofOphthalmology, Royal FreeHospital, Pond Street,London NW3 2QJ.Accepted for publication18 January 1990

Refsum's disease (heredopathica atactica poly-neuritiformis' 2) is an autosomally recessiveinherited absence of a hydroxylation of phytanicacid (3,7,11,15 tetramethyhexadecanoic acid),a breakdown product of chlorophyll foundespecially in dairy products. The disease ismanifested by a chronic polyneuropathy andcerebellar ataxia with retinitis pigmentosa and avariety of other ocular signs (Table). Symptomsbegin in the second or third decade with aninsidious, occasionally remitting course.

Pathological reports on Refsum's disease haveled to the findings of phytanic acid and lipidaccumulation in the liver, kidneys, heart, andcentral nervous system.3 Peripheral nerve studiesshow loss of myelinated nerve fibres with hyper-trophy and 'onion bulb' whorls of Schwann cells4and perineural fibrosis. Phytanic acid in lowconcentrations has been recovered from periph-eral nerves and in much higher concentrationsfrom the retina and ciliary body.5One necropsy report ofthe appearances within

the eye showed complete loss of photoreceptors,thinning ofthe inner nuclear layer, and reductionin the number of ganglion cells of the retina.6Sudan III and Sudan black stains demonstratedlipid loading in retinal vessels. Lipid had alsoaccumulated in the pigment epithelium of theretina, ciliary body, trabecular meshwork roundthe canal of Schlemm, and in both sphincter anddilator muscles of the iris, but not within thepigment epithelium in this case.6

Case reportIris of a 36-year-old man was obtained after anextracapsular cataract extraction and lensimplant and broad iridectomy. A diagnosis ofretinitis pigmentosa was made clinically 15 yearsago after he had presented with night blindnessand tunnel vision. There was no family history ofthe disease. Three years later he developed amixed sensory-motor polyneuropathy. A raised

TABLE Ocular and non-ocular signs in Refsum's disease

Ocular Non-ocular

Retinitis pigmentosa Peripheral neuropathyCataracts Cerebellar ataxiaMiosis Deafness/anosmiaOphthalmoplegia GoitrePtosis IchthyosisGlaucoma Cardiomyopathy

serum phytanic acid and sural nerve biopsyconfirmed the diagnosis of Refsum's disease.

Ocular examination prior to surgery revealedvisual acuities of 6/60 in both eyes, unreactivemiosis, bilateral posterior subcapsular cataracts,and extensive 'bone-corpuscular' retinitis pig-mentosa. The iris was fixed in formalin andglutaraldehyde and processed for light and elec-tron microscopy.

ResultsVacuoles of lipid, manifested by empty spaces,were visible in the biopsy. These were partic-

Figure 1: Vacuoles of lipid (arrowed) dissolved out duringprocessing, visible as spaces within the iris sphincter muscle,which is strained immunohistochemically with antibodies todesmin filaments; a capillary is indicated by the star. (x450.)

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Refsum's disease: electron microscopy ofan iris biopsy

zA B

Figure 2: A, B, C: Lipid droplets within the iris stromal cells and pigment epithelial cells. D: These droplets are ofsimilar sizeto the larger melanosomes ofthe IPE. (EM, x5200 (A), x24 500 (B, C, D.)

ularly easily seen within the sphincter muscle,especially when the immunohistochemical stainwith desmin antibodies was used (Fig 1). Unfor-tunately routine processing with toluene andalcohols removes lipid, and, though histo-chemical techniques, such as Nile blue sulphateand Sudan III and black were employed, un-surprisingly no specific staining was recordable.The electron microscopy of post-fixation osmi-fied tissue confirmed lipid deposition in theanterior border cells and stromal cells (Fig 2A, B,C). Similar lipid was shown among the melano-somes of the iris pigment epithelium (IPE) (Fig2D), a site at which no previous workers haddemonstrated such abnormal lipid droplets,though ciliary body and retinal pigment epithe-

lial deposits have been shown.6 The deposits offat within these IPE cells were of similar size tothe larger melanosomes found within the pig-ment epithelium (Fig 2D). As it could be sup-posed that such lipid deposits were secondary tocataract formation, a further review was under-taken ofa series ofiris biopsies from patients withFuchs's heterochromic cyclitis with cataract andtheir controls, five of each. These 10 sampleswere previously7 shown to have pigment epithe-lial cells covering a total of 53 grid squares, and amean of 221 melanosomal areas were counted,per case, necessitating examination of manymore. In this series no similar lipid inclusions tothose seen in the Refsum's case were seen,though some ofthe control patients were noted to

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Figure 3: Swollen and damaged unmyelinated axon lying within iris stroma, close to thesphincter. (EM, x26 000.)

have the intragranular vacuoles illustrated inZinn's classic paper on the melanosomes of theiris.

Axonal damage was seen within an unmyelina-ted nerve fibre (Fig 3) lying close to the anteriorborder, and fixation appeared adequate, withorganelle preservation elsewhere, so that thisappearance is unlikely to be artefactual. Suchmyxoid damage is usually associated with myeli-

nated nerve fibres in other sites in the body inRefsum's disease, but no myelin figures were

seen in this biopsy.

DiscussionThis demonstration of lipid droplets in the irispigment epithelium shows lipid can be depositedin any part of the layer of pigment epithelium

derived from neuroectoderm. Although the roleof the RPE as a phagocytic cell tissue devouringeffete rod outer segments is incontestable, it isnot usual to ascribe this function to the pigmentepithelia of the ciliary body and iris. The effectsof accumulation of phytanic acid residues innervous tissues may be primary, as is thought tobe the case in myelin synthesis9 with incorpora-tion of a 'thorny' molecule instead of straightchain fatty acids. A similar mechanism mayoccur in the retina in membrane lipids, withconsequent low lineoleate levels, known to in-fluence electroretinograms.'0 The accumulationin pigment epithelia might be unrelated tothe primary disorder or secondary effect whichproduces a clinical pattern similar to classicalretinitis pigmentosa.The ocular effects ofthis disease may therefore

be primary leading to ptosis, miosis, ophthal-moplegia, and retinal malfunction, or secondarywith further retinal damage due to RPE disease.Cataract may also be secondary to the accumula-tion of lipid within the lens epithelium itself or todisruption ofthe function ofthe ciliary body, andphysical disruption is seen in glaucomatous eyes.

1 Refsum S. Heredataxis hemaralopica polyneuritiformis, ettidligere ikke beskrevet familiert syndrome? En Forelobigmeddelelse. NordMed 1945; 28: 2682-91.

2 Refsum S. Heredopathia atactica polyneuritiformis: a familialsyndrome not hitherto described; a contribution to theclinical study of the hereditary diseases of the nervoussystem. Acta Psychiatr Scand 1946; supply 38: 303.

3 Durand JF, Noel P, Rutsaert J, Toussaint D, Malmendier C,Lyun G. A case of Refsum's disease: clinical pathologicalultrastructural and biochemical study. Pathol Eur 1971; 6:172-91.

4 Ferdeau H, Engel WK. Ultrastructural study of a peripheralnerve biopsy in Refsum's disease. J Neuropathol Exp Neurol1969; 28: 278-94.

5 Levy IS. Refsum's syndrome. Trans Ophthalmol Soc UK 1970;90: 181-6.

6 Toussaint D, Danis P. An ocular pathological study ofRefsum's syndrome. AmJr Ophihalmol 1971; 72: 342-7.

7 McCartney ACE, Bull TB, Spalton DJ. Fuchs's heterochromiccyclitis: an electron microscopic study. Trans OphthalmolSoc UK 1986- 105: 324-9.

8 Zinn KM, Mockel-Pohl S, Villanueva V, Furman M. The finestructure of iris melanosomes in man. Am J Ophthalmol1973; 76: 721-9.

9 Steinburg D. Phytanic acid storage disease (Refsum's disease).In: Stanbury JB, Wyngaarden JB, Fredrickson DS, Gold-stein JL, Brown MS, eds. The metabolic bass of inheriteddisease. 5th ed. New York: McGraw Hill, 1983: 731-47.

10 Leat WMF, Curtis R, Millichamp NJ, Cox RW. Retinalfunction in rats and guinea-pigs reared on diets low inessential fatty acids and supplemented with linoleic orlinolenic acids. Ann NutrMetab 1986; 30: 166-74.

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