Anterior membrane dystrophy following cataract extraction

British Journal of Ophthalmology, 1979, 63, 331-335

Anterior membrane dystrophy followingcataract extractionJOHN D. BRODRICKFrom the University of Texas Health Science Center, Dallas, USA

SUMMARY This paper describes a patient with previously normal corneas who underwent bilateralcataract surgery. This was followed by acute dehiscence of the epithelium and the eventualappearance of fingerprint lines, microcysts, and map-like areas typical of Cogan's microcysticdystrophy. Light and electron microscopy showed the presence of epithelial microcysts and a seamof subepithelial material like basement membrane. It is suggested that this patient represents arapid transition from apparent normality to an extensive anterior membrane dystrophy, precipitatedby operation for cataract.

A unique corneal complication of cataract surgeryis presented in this paper, which describes thebilateral acute onset of an anterior membranedystrophy. Fingerprint lines of the cornea were firstdescribed by Guerry as fine wavy lines with whorl-like contours located within the corneal epitheliumand best seen by retroillumination (Guerry, 1950).He noted similar lines in keratoconus and advancedFuchs's dystrophy. His clinical observations wereconfirmed and supplemented by subsequent authors,who demonstrated histologically a splitting ofBowman's membrane (DeVoe, 1962; Kaufman andClowers, 1966). Recent authors have includedfinger-print, net, and bleb dystrophies with Cogan'smicrocystic dystrophy (Cogan et al., 1964) in acomplex of interrelated superficial corneal disorders,the anterior membrane dystrophies (Bron andBrown, 1971; Trobe and Laibson, 1972). It hasbeen suggested that anomalies of the basementmembrane are the prime cause of both the finger-print lines and the epithelial microcysts (Coganet al., 1974; Rodrigues et al., 1974).

Fingerprint striae have recently been describedboth as an idiopathic dystrophic form (Brodricket al., 1974a) and as an accompaniment of herpessimplex keratitis (Brodrick et al., 1976). There isonly one previous report of the condition occurringin an aphakic patient (Rodrigues et al., 1974), butno mention has been made of the explosive onsetand progressive course seen in the case discussedhere. This contrasts with a recent report of 5 patients

Address for reprints: Professor John D. Brodrick, Universityof Texas, Department of Ophthalmology, SouthwesternMedical School, 5323 Harry Hines Boulevard, Dallas,Texas 75235, USA

with Cogan's microcystic dystrophy who had intra-ocular surgery without any unfavourable effectsexcept for mild progression in one patient(Luxenberg et al., 1975).

Case report

A 62-year-old Caucasian woman with no previoushistory of ocular or general disease was first seen in1970 with failing vision due to bilateral cataracts.Corneal examination at that time was normal. By1972 her vision had deteriorated considerably andlens extraction was recommended. Apart from thecataracts, preoperative examination of her eyesrevealed no other abnormality.

In September 1972 a routine intracapsular lensextraction was carried out with an uneventful post-operative period. Three weeks later she developeda sensation of a foreign body in the left eye whichrapidly became intensely painful, accompanied byextreme photophobia and lacrimation. Examinationshowed swelling of the left eyelids, intense blepharo-spasm, and profuse tearing. There was markedconjunctival hyperaemia, and the left corneaappeared hazy.

Slit-lamp examination showed that the lower halfof the cornea was covered by circumferential whorlswhich closely resembled a thumbprint (Fig. 1). Athigh magnification these whorls were seen to consistof multiple small ridges in oedematous epitheliumwhich was heaped up into folds. Moreover the wholeof the affected area was slightly mobile and wasdehiscing from the underlying basal lamina andstroma. No staining was noted, but the tear filmwas broken up by the epithelial ridges. Bowman's

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332 John D. Brodrick

the right eye. Examination revealed swelling of thelids, intense blepharospasm, lacrimation, and photo-phobia. The conjunctiva was hyperaemic and thelower half of the cornea appeared hazy. Slit-lampexamination showed that the upper half of thecornea was normal; the lower half was oedematousand heaped up into striae, the appearances beingidentical to those previously seen in the left cornea.The epithelium was extremely mobile, and, as inthe left cornea, though no stain was present thetear film was broken up by the epithelial striae.Corneal sensation was reduced. There was noapparent abnormality of Bowman's layer, the

Fig. I Drawing of cornea to illustrate the overalldistribution of the epithelial whorls

layer appeared normal, and there was no evidenceof stromal oedema. The stroma measured 05 mmwith a normal endothelium and Descemet's mem-brane. The anterior chamber showed no significant *flare or cells and the vitreous face was intact and Lwell back. Intraocular pressure was 18 mmHg byapplanation tonometry. Corneal sensation was Fig. 2 Photograph of cornea showing the large map-likegreatly reduced. areas in the centre (x 1)

Treatment was continued with atropine andcorticosteroid drops and admission was arrangedfor epithelial debridement 3 days later. In this shorttime, however, all striae and affected epitheliumwere shed and her symptoms completely abated.Biomicroscopy now showed that the whorls had;been replaced by scattered epithelial microcysts andgreyish map-like areas consistent with the diagnosisof Cogan's microcystic dystrophy (Fig. 2). Thecornea was otherwise normal apart from the de-

Since then she has experienced intermittentepisodes of discomfort and foreign body sensation,particularly on awakening in the morning, tendingto alleviate as the day progressed. By January 1973in addition to the features of Cogan's microcystic 3dystrophy some fine fingerprint striae had appearedin the nasal periphery (Fig. 3). Throughout thisperiod the right cornea was entirely normal toclinical examination.

In May 1973 an uncomplicated intracapsular lensextraction was performed on the right eye withan uneventful postoperative period. Twelve weeks Fig. 3 Drawing of cornea to illustrate the distributionafterwards severe pain and discomfort developed in of map-like areas, fingerprint striae, and microcysts

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Anterior membrane dystrophy following cataract extraction

stroma, Descemet's membrane, or the endothelium.The anterior chamber was quiet, the vitreous face

intact and well back, and the intraocular pressurewas 19 mmHg by application tonometry. Theaffected epithelium was removed immediately undertopical anaesthesia. The specimen was divided into2; one half was fixed in formalin and embedded inparaffin for conventional microscopy, the other halfwas fixed in cold 2 5% gluteraldehyde, washed, andpostfixed in 1% osmium tetroxide and embedded inAraldite for electron microscopy.Her subsequent progress has been satisfactory,

with a corrected vision of 20/25 in each eye. Shestill has intermittent attacks of discomfort and aforeign body sensation affecting both eyes, usuallywhen she wakes in the morning. They tend toimprove as the day progresses. There have been nofurther attacks of intense pain.

Examination in 1974 showed the following cornealappearances. In the right central cornea a greyish,map-like area with fine linear borders was visible,lying in thq deep aspect of the epithelium. Some finefingerprint striae were seen in the upper nasal andlower temporal periphery, and scattered epithelialmicrocysts were evident both centrally and peri-pherally. The microcysts and fingerprint striae werebest seen by retroillumination and showed reverseillumination, denoting increased optical density oftheir contents (Graves, 1924). The left corneashowed numerous whorled fingerprint striae mainlyin the nasal half of the cornea. Some scatteredepithelial microcysts were observed in the supra-nasal quadrant, and a greyish map-like area couldbe seen just below the centre of the cornea. Thestriae and microcysts were best seen by retro-illumination and showed reverse illumination as inthe right eye. Schirmer's test with local anaesthesiarevealed decreased lacrimal secretion, 4 mm in 5minutes in the right eye, 3 mm in 5 minutes in theleft eye. The tear film showed break-up over thearea of the fingerprint striae, so that linear dryzones rapidly became apparent. The anterior cornealmosaic was interrupted in the areas of the epithelialchanges. The microcysts showed no affinity forfluorescein. Corneal sensation assessed with mono-filament silk of varying calibre was normal. In botheyes the corneal stroma was normal, with no visibleabnormality of Bowman's layer, Descemet's mem-brane, or the endothelium. The anterior chamberswere deep and quiet, the vitreous face intact andwell back, and intraocular pressure 19 mmHg byapplanation tonometry.

LIGHT MICROSCOPYThe specimen comprised epithelium, basal lamina,and some superficial stromal lamellae. The epithe-

lium showed the normal 5-layered structure. Thecellular morphology was essentially normal, withno evidence of pleomorphism, acanthosis, oracantholysis. There was no dysplasia, but scatteredareas of spongiosis were noted. Epithelial micro-cysts of varying shape and size were located atdifferent levels (Fig. 4). In some areas pale stainingbasal cells were observed. The microcysts containeda mixture of intensely basophilic coarse granulesand a pale blue, finely granular substance. Thenuclei were pyknotic, and the intercellular debriswas characteristic of degenerating epithelial cells.A thin seam of moderately basophilic, homo-

geneous material was present deep to the apparentlynormal basal lamina. In some sections smallprojections from this seam appeared to intrude intothe epithelium. The subepithelial material wasperiodic acid Schiff negative (Fig. 5).

ELECTRON MICROSCOPYThe epithelial microcysts presented a typical ap-pearance with microvillous projections into a cavitycontaining a variety of degenerating organelles andnuclear material (Fig. 6). The subepithelial seamconsisted of a matrix of closely-packed granules80 A in diameter containing randomly interspersedfibrillae 170 A (17 nm) in width, banded at 125-Aintervals. In some areas this seam projected up intothe epithelium. The basement membrane andBowman's layer were of normal thickness andcontour and the superficial stromal lamellae werenormal.

Discussion

This case is of interest because it represents atransition from a clinically normal asymptomatic

Fig. 4 Section of epithelium showing marked dysplasia,a superficial microcyst (M), and a layer ofabnormalsubepithelial tissue intruding up into the epithelium(Masson, x 500)

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Fig. 5 Section of epithelium showing subepithelial seamof abnormal tissue (S) invaginating the grossly thickenedbasement membrane (B) up into the epithelium. Clearspaces (arrowed) are artefacts, but possibly represent aplane of cleavage caused by fingerprint line (F) (Masson,x 1750)

cornea through an acute episode of epithelialdehiscence to an established anterior membranedystrophy of the Cogan's microcystic and fingerprintvariety.

Epithelial microcysts are a feature of many cornealdisorders, including the recurrent erosion syndrome(Tripathi and Bron, 1972), Meesman's epithelialdystrophy (Kuwabara and Cicarelli, 1964), andCogan's microcystic dystrophy (Guerry, 1965). Theirpresence has also been noted in a complex of inter-related superficial corneal disorders (Bron andBrown, 1971) now regarded as a distinct group, theanterior membrane dystrophies. The microcystsdescribed in these various conditions appear histo-logically identical (Rodrigues et al., 1974; Brodricket al., 1974, 1976). Although the precise mechanismof the microcyst formation is still in dispute, severaltheories exist to account for it, including theinhibited migration theory of Cogan et al. (1974)and the inverted basal cell theory of Rodrigues(Rodrigues et al., 1974). They may, however,represent a much more basic entity (Brodrick et al.,1974), and it would seem reasonable to suggestthat the cornea, whose unique and fundamentalproperty is its transparency, has by virtue of itsavascular nature only a limited number of inherentpathological responses. It has been suggested that

the microcyst reaction represents a process wherebythe corneal epithelium secludes and deletes degener-ating cells, a type of epithelial phagocytosis, althougha true phagosome is probably not formed (Brodricket al., 1974).The seam of subepithelial material which probably

results from disordered metabolism of the basalepithelial cells readily explains the defective epithelialadhesion. A similar seam has been documented as thebasis of fingerprint dystrophy (Brodrick et al., 1974).

It has frequently been commented that thesuperficial corneal disorders represent a broadspectrum of probably interrelated disorders, and asearch has been made for a common pathogenesiswhich may not, however, exist. It is more probablethat a variety of aetiological agents, including a truedystrophic process in the basal cells, can pursue afinal common path to produce a similar ultra-structural and clinical appearance.The importance of the present case is that it

represents a rapid evolution, probably precipitatedby surgery, from clinically normal cornea to thetypical appearances of Cogan's microcysticdystrophy with fingerprint lines. The intermediatephase of acute epithelial dehiscence is similar to the

lig. 6 Electronmicrograph showing epithelial microcystwith microvillous lining and degenerating cellular debrisin the cyst cavity (uranyl acetate and lead citrate, x 800)

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Anterior membranie dystrophy following cataract extraction

superficial linear keratitis described by Spicer andGreeves (1916). An unusual feature was the localisa-tion entirely in the lower half of each cornea. Onemight have expected these changes to occur in theupper half adjacent to the cataract incision, wherethe effects of surgical trauma and the interferencewith nutrition and sensation would be maximal.It is difficult to explain this distribution.

This case, apart from its unusual features, addsfurther support to the concept that a series ofdissimilar epithelial reactions may be transitionalstates in a spectrum of related disorders. Thefundamental disorder common to the group isprobably a disturbance in the metabolism of thebasal epithelial cells. This results in the formationof the subepithelial material responsible forepithelial adhesion problems and fingerprint linesand triggers off the formation of microcysts, enablingthe cornea to degrade and extrude degenerating anddamaged cells by a process which does not prejudiceits normal avascularity and transparency.

References

Brodrick, J. D., Dark, A. J., and Peace, G. W. (1974).Fingerprint dystrophy of the cornea. Archives of Ophthal-mology, 92, 483-489.

Brodrick, J. D., Dark, A. J., and Peace, G. W. (1976).Fingerprint lines of the cornea in herpes simplex keratitis.Annals of Ophthalmology, 8, 481-484.

Bron, A. J., and Brown, N. A. (1971). Some superficialcorneal disorders. Transactions of the OphthalmologicalSocieties of the United Kingdom, 91, 13-29.

Cogan D. G., Donaldson, D., and Kuwabara, T. (1964).Microcystic dystrophy of the corneal epithelium. Trans-

actions of the American Ophthalmologic Society, 62, 213-225.

Cogan, D. G., Kuwabara, T., Donaldson, 0. O., andCollins, E. (1974). Microcystic dystrophy of the cornea.Archives of Ophthalmology, 92, 470-474.

DeVoe, A. G. (1962). Certain abnormalities of Bowman'smembrane with particular reference to fingerprint linesin the cornea. Transactions of the American OphthalmologicSociety, 60, 195-201.

Graves, B. (1924). A bilateral chronic affection of the endo-thelial face of the cornea of elderly persons with anaccount of the technical and clinical principles of its slit-lamp observation. British Journal of Ophthalmology, 8,502-544.

Guerry, D. (1950). Fingerprint-like lines in the cornea.American Journal of Ophthalmology, 33, 724-727.

Guerry, D. (1965). Observations on Cogan's microcysticdystrophy of the corneal epithelium. Transactions of theAmerican Ophthalmologic Society, 63, 320-334.

Kaufman, H. E., and Clower, J. W. (1966). Irregularities ofBowman's membrane. American Journal ofOphthalmology,61, 227-230.

Kuwabara, T., and Cicarelli, E. C. (1964). Meesman'scorneal dystrophy. Archives of Ophthalmology, 71, 676-682.

Luxenberg, M. N., Friedland, Beth R., and Holden, J. M.(1975). Superficial microcystic corneal dystrophy. Archivesof Ophthalmology, 93, 107-1 10.

Rodrigues, M. M., Fine, B. S., Laibson, P. R., andZimmerman, L. E. (1974). Disorders of the epithelium.Archives of Ophthalmology, 92, 475-482.

Spicer, W. T. N., and Greeves, R. A. (1916). On superficiallinear keratitis together with an account of the patho-logical examination of two affected eyes. Ophthalmoscope,14, 116-120.

Tripathi, R. C., and Bron, A. J. (1972). Ultrastructural studyof non-traumatic recurrent erosion. British Journal ofOphthalmology, 56, 73-85.

Trobe, J. D., and Laibson, P. R. (1972). Dystrophic changesin the anterior cornea. Archives of Ophthalmology, 87,378-382.

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Anterior membrane dystrophy following cataract extraction