A C T A O P H T H A L M O L O G I C A VOL. 5 3 1 9 7 5

University Eye Department (Head: Professor Thore Lie Thomassen)

and the Institute of Pathology, Electron Microscopic Laboratory (Head: Torstein Hovig, M . D.), Rikshospitalet, Oslo, Norway

THE PSEUDO-EXFOLIATION SYNDROME. A SCANNING ELECTRON MICROSCOPIC STUDY

II. The posterior chamber region

BY

MARTIN DAVANGER

The distribution of pseudo-exfoliation (PE) material as well as the finer details of its surface has been studied by scanning electron microscopy on the surfaces facing the posterior chamber. The specimens were fixed in glutaraldehyde and 0 9 0 4 and dried by the critical point method, after careful dissection of the anterior hyaloid surface. Granules and plaques of PE material were found to attach to the iris, to the ridges of the ciliary processes, to the zonules, and along radial stripes on the anterior hyaloid surface, one for each zonule touching this surface. It seems as if the PE material is located mainly on sites of contact between two sur- faces. In high magnification it is found that the surface of the PE material is formed by an irregular meshwork of fibrils, the diameter of which is about 550-700 A. The fibrils are characteristically coiled, partly into re- gular spirals. The hypothesis is put forward that these fibrils are formed by a condensation of mucopolysaccharides forming the ground substance of the PE material.

Key words: pseudo-exfoliation - scanning electron microscopy - posterior chamber - aqueous - zonules of Zinn - anterior hyaloid - ciliary body - iris - mucopolysaccharide.

Received May 13, 1975.

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F i g . 1. PE granules attached to zonules (A), and in radial stripes to the anterior hyaloid surface (B). Incident light microscopy. A: x 50, bar = 0.1 mm. B: x 90, bar = 0.1 mm.

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The Pseudo-exfoliation Syndromc

Pseudo-exfoliation (PE) material is widely distributed on the surfaces facing the posterior chamber. This material may be found on the posterior surface of the iris, on the ciliary processes, the zonules, and on the anterior hyaloid membrane. Sunde (1956) described the gross anatomical distribution of PE material on these surfaces, studied by the help of a dissecting microscope.

It has been shown that the PE material on the anterior lens surface may be recognized and studied by scanning electron microscopy (SEM) (Benedikt 1973, Benedikt et al. 1973a,b, Davanger 1975b). This method has the advan- tage of yielding much higher magnification and better depth resolution as compared with incident light microscopy.

The structures of the posterior chamber region of the normal eye have been examined by SEM by the present author (Davanger 1975a). The two previous

~~

Fig. 2. General view of the lens equator, the zonules and the ciliary processes. Plaques of PE material attach to the ridges of the ciliary processes and to the zonules. Area

indicated by arrow is seen in higher magnification in Fig. 3. x 30, bar = 0.5 mm.

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Martin Davanger

works mentioned (Davanger 1975a,b) have formed the basis for the present study of the distribution of the PE material in the posterior chamber region and of the surface structure of this material.

Material and Methods

The anterior segment of 3 human eyes with PE have been examined. Two of these eyes were enucleated because of absolute painful glaucoma, while the third was removed because of a malignant melanoma not affecting the anterior segment. The methods of preparation are described in earlier works (Davanger 1975a,b). The careful dissection of the anterior part of the vitreous was per-

Fig. 3. A conglomerate of PE granular material attached to the surface of the ridge of a

ciliary process. This area is also seen in Fig. 2. x 525, bar = 50 ,urn.

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The Pseudo-exfoliation Syndrome

Fig . 4. A group of zonules is enclosed in an accumulation of PE material. Thin strands enmesh

the zonules and the PE material. x 1075, bar = 10 pm.

formed after dehydration while the specimens were suspended in acetone. The specimens were dried by the critical point method, by which deformation of the specimens were avoided without the application of epon as described in earlier work (Davanger 1975a).

The ciliary body, the zonules and the anterior surface of the vitreous was also photographed by incident light microscopy, while the specimens were submerged in acetone.

Results

Light microscopy. Granules of PE material were found to adhere to the zon- ules, which sometimes were completely covered (Fig. 1 A). Granules of PE were also found to adhere to the anterior hyaloid surface in radial stripes, one for each zonule which touched this surface (Fig. 1 B). This phenomenon is also described by Sunde (1956). The radial stripes of PE material were several times broader than the diameter of the zonules.

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During the dissection of the specimens under a dissecting inicroscope it was observed that the PE material might anchor the zonules to the anterior hyaloid membrane. Sometimes the PE material was removed from the zonules, or from parts of them, during the process of lifting off the hyaloid membrane from the zonules.

Scanning electron microscopy. A general view of the ciliary body and the zon- ules in a case of PE is given in Fig. 2. Plaques of PE material are seen to be attached to parts of the surface of the ciliary processes, preferrably to the most prominent part of the ridges. Smaller accumulations of PE material were found to be attached to the zonules. In the case demonstrated in Fig. 2,

Fig. 5. PE material attached to the anterior hyaloid surface in continuous radial stripes in the zone of contact with the zonules. Grooves (between arrows) run along the ridge of these stripes. Area indicate by angles is seen in higher magnification in Fig. 6.

x 190, bar = 0.1 mm.

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The Pseudo-exfoliation Syndrome

Fig. 6. PE material on the anterior hyaloid membrane. This area is seen also in Fig. 5. A groove (between arrows) along the ridge of the radial stripe is covered with thin longitudinally running filaments. The PE granules indicated by right angles are seen

in higher magnification in Fig. 7. x 1490, bar = 10 pm.

however, most of the PE material followed the anterior hyaloid during the dissection and was removed from the zonules.

A cobweb-like net consisting of thin strands is seen to be suspended between the zonules (Fig. 2).

The plaques of PE material attached to the ridges of the ciliary processes were found to consist of a conglomerate of PE granules, whose diameter was in the range of 5-10 pm (Fig. 3). The granules frequently coalesced into larger lumps. The material seemed to be anchored upon the surface of the ciliary

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Martin Davanger

Fig. 7. PE material on the anterior hyaloid. The surface is formed by a meshwork of fibrils,

which are coiled to make spirals. x3790, b a r = 5 pm.

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The Pseudo-exfoliation Syndrome

Fig. 8. Fibrillar surface of PE granules on a ciliary process. x 4740, bar = 5 pm.

processes, the material being sharply demarcated and clearly protruding above the epithelial surface. This surface, and also the zonules, appeared normal at those areas which were not covered by the PE material.

PE material attached to zonules is seen in more detail in Fig. 4. A group of zonules is enclosed in an irregular mass, in which, however,' small PE granules may be recognized. Numerous thin cobweb-like strands, most of them straight but some curled, enmesh the zonules and the PE material (Fig. 4).

The anterior row of zonules was usually found to be enveloped in irregular masses of PE material. Thereby large groups of zonules were completely hid- den for a part of their course.

The PE material attached to the anterior hyaloid surface was found to be arranged in radially directed stripes (Fig. 5) , as it was found also by light microscopy. In the case demonstrated in Fig. 5, the stripes of PE material are

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Mart in Davanger

continuous, the surface is amorphous and PE granules are not easily seen at this magnification.

A groove was frequently seen to run along the ridges of the continuous PE stripes on the anterior hyaloid surface (Fig. 5) . The surface of these grooves was f,ound to be covered by thin longitudinally running filaments (Fig. 6). Obviously, the groove represents the cast of a zonule, which has been lifted off during the preparation of the specimen.

The accumulations of PE material on the anterior hyaloid were found to be sharply demarcated and to protrude above the surface of the membrane, which seemed to be normal in those areas which were not covered.

On the posterior surface of the iris plaques consisting of clusters of typical PE granules were found. The diameter of the granules was in the range 5-10 ,um.

Fig. 9. Coiled fibrils on the surface of PE material on the anterior hyaloid. Some regular

spirals are seen. x 1 1 950, bar = 1 pm.

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The Pseudo-exfoliation Syndrome

Fig. 10. Coiled fibrils with spirals on the surface of PE material on the anterior hyaloid.

x 29 500, bar = 0.5 pm.

At higher magnifications (Figs. 7, 8, 9 and 10) it could be seen that the sur- face of the PE material consisted of an irregular meshwork of fibrils, with the same characteristics as it has been described for the PE material on the anterior lens surface (Davanger 1975b). At the higher magnifications the sur- face of the PE material was found to be about the same or similar at all the locations studied in this work.

The fibrils were characteristically coiled into more or less regular spirals. The dimensions of the fibrils and the spirals were found to be similar to that described for the PE material on the anterior lens surface (Davanger 1975b). The diameter of the fibrils was found to be in the range 500-750 A, their length often exceeded 4 pm. The outer diameter of the spiral was found to be about 1/6 pm, and the distance between neighboring loops has been meas- ured to ca. 1/3 pm.

Discussion

The PE material of the posterior chamber region has a surface which is similar to that found for the PE material on the anterior lens capsule (Davanger 1975b) : In moderate magnifications PE granules are found, similar to those

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Martin Davanger

of the peripheral band on the lens. And in higher magnifications the same meshwork of coiled fibrils can be demonstrated.

The nature of these fibrils is discussed in a recent paper (Davanger 1975b). It can not be excluded that the SEM fibrils described are formed by the pro- tein fibrils well known from transmission electron microscopy. Another pos- sibility, however, is that they represent a condensation product of mucopoly- saccharides, proteoglycosaminoglycans, forming the ground substance of the PE material.

The distribution of the P E material may help to throw some light on its formation. The surfaces of the anterior eye to which the PE material is at- tached are of widely different nature (anterior lens capsule, iris, ciliary body, zonules and the anterior hyaloid surface). These surfaces have in common that they are facing the aqueous humour. Non of the surfaces consist of cell mem- branes (the epithelium of the iris and the ciliary body being covered by a basement membrane facing the aqueous humour).

Further, it seems as if the material is located mainly on sites of contact between two surfaces, between which slight relative movements are possible. Most striking is the accumulation of PE material along the lines of contact between the zonules and the anterior hyaloid surface. Similarly, the distribu- tion of PE material on the anterior lens surface is evidently influenced by the contact of this surface with the iris (Sunde 1956, Benedikt 1975, Benedikt et al. 1973a,b, Davanger 197513). Also the conglomerates of PE material at- tached to the ridges of the ciliary processes seem to be located on sites of contact with the anterior hyaloid.

The distribution of the PE material on different surfaces of the anterior eye, as well as the surface details of the material itself, is best understood on the assumption that the material consists of deposits formed by a condensation and/or an accumulation of substances from the aqueous.

The present work does not give any positive information about the original source of these substances.

References

Benedikt, 0. (1973) Morphologische Veranderungen beim sogenannten Exfoliations- syndrom. Klin. Mbl. Augenheilk. 162, 465-477.

Benedikt, O., Aubeck, L., Gettinger, W. & Waltinger, H. 1973a): Vergleichende rasterelektronenmikroskopische and transmissionselektronenmikroskopische Unter- suchungen an Linsen bei sogenannten Exfoliationssyndrom. Albert v. Graefes Arch. klin. exp. Ophthal. 187, 249-264.

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The Pseudo-exfoliation Syndrome

Benedikt, O., Gettinger, W. & Aubeck, L. (1973b) Klinik und Ultrastruktur der zen- tralen Scheibe beim sogenannten Exfoliationssyndrom. Acta Ophthal. 51, 21 1-224.

Davanger, M. (1975a) The suspensory apparatus of the lens. The surface of the ciliary body. A scanning electron microscopic study. Acta Ophthal. 53, 19-33.

Davanger, M. (1975b) The pseudo-exfoliation syndrome. A scanning electron micro- scopic study. Part I: The anterior lens surface. Acta Ophthal. 53, 809-820.

Sunde, 0. A. (1956) On the socalled senile exfoliation of the anterior lens capsule. A clinical and anatomical study. Acta Ophthal., suppl. 45.

Author’s address: Martin Davanger, M. D., University Eye Department, Rikshospitalet, Oslo, Norway,

Acta ophthal. 53, 6 833

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