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Ultrastructural Study of Cataract in Myotonia Dystrophica
666
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
ULTRASTRUCTURAL STUDY OF CATARACT IN MYOTONIA DYSTROPHICA ANTHONY J. DARK, M.D., AND BARBARA W. STREETEN, M.D. Syracuse, New York
Characteristic iridescent particles de velop in a narrow zone of the lens cortex in most patients suffering from myotonia dystrophica. The particles seen in optical section are separated by a clear zone of discontinuity from the anterior and pos terior capsules. They do not interfere with vision. In some patients, however, they are followed by the development of pos terior subcapsular opacities that are ophthalmoscopically visible as stellate cata racts. Opacification of the entire lens may develop as the final stage.1'2 Structural studies on cataract myotonia dystrophica have been inconclusive and confined to light microscopy.3 Two re cently obtained myotonic cataracts have enabled us to undertake electron micro scopic studies.
removed with cryoprobes after the appli cation of chymotrypsin. The lens from the patient in Case 1 was placed in 10% formalin, the lens from the second patient was fixed in ice cold 2.5% glutaraldehyde in phosphate buffer at pH 7.2. Half of the formalin-fixed lens was processed in par affin for routine histology. Free slices were examined by polarization micros copy. Pieces of capsule and underlying cortex were taken from both lenses and osmified and then embedded in an epoxy resin. One-micron sections were stained with toluidine blue and studied by light microscopy. Ultrathin sections were treat ed with uranyl acetate and lead citrate before examination by transmission elec tron microscopy.
SUBJECTS AND METHODS
Abnormal findings were present in the lens capsule, anterior subcapsular epithe lium, and the lens cortex. Light microscopy—Numerous capsular inclusions, similar to those seen in aging lenses, were visible in the pre-equatorial zone. Fine vertical striae were present in the deep portion of the capsule in this zone. The anterior subcapsular epithe lium had clear vacuoles, which were espe cially numerous in Case 1 but scarce in Case 2. The deep subcapsular cortex con tained minute vacuolated ovoid bodies, most of which were 6 to 15 μ long; a few reached 35 μ (Fig. 1). They corresponded in size and distribution with the irides cent particles seen biomicroscopically. In polarized light these bodies exhibited a characteristically variegated, spiral birefringance (Fig. 1, inset). The posterior subcapsular and cortical changes do not differ from those seen in senile cataracts. Electron microscopy—Embedded in
Two unrelated patients with classic myotonic dystrophy underwent cataract extraction; we used the two lenses in this study. A 54-year-old white woman (Case 1), and a 61-year-old white man (Case 2) had been examined by slit-lamp mi croscopy preoperatively. In both patients, approximately symmetrical lens changes included the presence of a deep subcapsu lar zone of iridescent particles together with posterior subcapsular and minimal cortical cataract. The lenses were From the Department of Ophthalmology, Veter ans Aministration Hospital (Dr. Dark); and the De partments of Ophthalmology (Drs. Dark and Streeten) and Pathology (Dr. Streeten), Upstate Medical Center, Syracuse, New York. This study was supported in part by the Medical Research Service of the Veterans Administration and by Re search Grant EY 01602 from the National Eye Institute. Reprint requests to Anthony J. Dark, M.D., De partment of Ophthalmology, Veterans Administra tion Hospital, Syracuse, NY 13210.
RESULTS
VOL. 84, NO. 5
CATARACT IN MYOTONIA
Fig. 1 (Dark and Streeten). Case 1. Unstained lens slice showing vacuolated oval bodies (arrows) in deep subcapsular zone (x50). Inset shows spiral configuration of single body (xllO).
the pre-equatorial capsules were numer ous filament-containing inclusions (Fig. 2). The filaments, which were 8 to 12 nm wide, appeared as hollow tubes in cross section (Fig. 3). They showed occasional banding at 50 nm. The deep capsular striae seen with the light microscope were columns of cytoplasmic material extend ing vertically outward from the bases of subjacent epithelial cells (Fig. 4). The proximal portion of these columns con-
667
tained a cell process, but the more distal part was often occupied by cytoplasmic granules and capsular filaments (Fig. 4, inset). The deep layer of the capsule showed multilaminar basement mem brane formation parallel to the capsular surface except where it was oriented alongside cytoplasmic processes and granules. In all regions, the subcapsular epithe lium showed a variable number of mem brane bound vacuoles. In Case 1 these changes were so marked that they appar ently represented artifacts. Occasional shrunken electron-dense cells were pres ent in this layer, sometimes surrounded by live cells (Fig. 5). Mitochondria showed high amplitude swelling (Fig. 5). Lipid droplets were seen regularly in many of the epithelial cells (Fig. 6). In occasional cells were crystalloid accumu lations of protein. (Fig. 6). Scattered through the anterior lens cor tex were numerous vacuoles containing whorls of multilaminated membranes (Fig. 7). The larger vacuoles correspond ed in size, number, and distribution with
Fig. 2 (Dark and Streeten). Case 1. Pre-equatorial lens capsule contains numerous filamentous inclusions. Elongated cytoplasmic processes (E) of the adjacent epithelium extend into the deep layer of capsule (x 17,300).
668
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
Fig. 3 (Dark and Streeten). Case 2. Detail of pre-equatorial capsule shows tubular appearance of filaments in cross section (x62,700).
the biréfringent ovoid bodies observed in light microscopy. The laminae exhibited uniform thickness and staining properties within a given vacuole, but varied consid erably in width (2 to 70 nm) and electron density in different vacuoles. Some vacu oles contained only granular, electrondense material. Arrays of reduplicated plasmalemmalike membranes, 2 nm wide, were also found in the anterior cortex. They were between lens fibers and appeared as par allel, slightly wavy lines (Fig. 8), or in arched configurations (Fig. 8, inset). Con centric arrangements (Fig. 9) of similar membranes were also seen in this region. The posterior subcapsular and cortical opacities revealed globular degeneration
of lens fibers and other nonspecific cataractous changes. DISCUSSION
Capsular inclusions containing fibrillar protein are an almost universal finding in aging lenses. 4,5 They are particularly abundant in pseudoexfoliative disease. Little is known of their significance, ex cept that they resemble zonular protein and may be synthesized by the underly ing epithelial cells. 4 The profusion of capsular inclusions present in both pa tients was greater than we have seen in senile cataract, either with or without pseudoexfoliation. The stimulus for their excess in myotonia dystrophica is un known. The presence of elongated epithelial
CATARACT IN MYOTONIA
VOL. 84, NO. 5 iJv;
Di
tuta ,'0 ^ 'iftî.i;
M
Fig. 4 (Dark and Streeten). Case 2. Pre-equatorial lens capsule. Vertical columns (G) contain cytoplasmic granular material and filaments (x 7,500). Inset shows cell processes at base of column (x 10,000).
669
670
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
*>*
'■'".■fS-'Ì;i
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,
.
Fig. 5 (Dark and Streeten). Case 2. Anterior lens epithelium. Dead cell surrounded by live epithelial cell; capsule (C); mitochondria (M) showing segmental distension (x 12,500).
cell processes extending into the deeper layers of the pre-equatorial capsule is also not specific for myotonia dystrophica. Seland 5 noted them in the postequatorial capsule in patients as young as 17 years old, and we have observed them in the pre-equatorial capsule in pseudoexfoliative disease. The presence of cytoplasmic granules outside the cell membrane of these processes is difficult to interpret. It may represent exocytosis, 6 or result from
degenerative changes in the cell proc esses. The subcapsular epithelial cells showed changes indicative of chronic in jury, including lipid droplets, watery vacuolations of the cytoplasm, and cell death. 7 Oil droplets were also a feature of the sarcoplasmic changes observed by Kuwabara and Lessel 8 in extraocular muscle of patients with myotonia dystro phica.
VOL. 84, NO. 5
CATARACT IN MYOTONIA
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Fig. 6 (Dark and Streeten). Case 2. Anterior lens epithelium showing lipid droplets (x29,600). Inset illustrates a protein crystalloid (x21,800).
Fig. 7 (Dark and Streeten). Case 1. Anterior subcapsular cortex. Larger (12μ) vacuole containing multilaminar whorls (x 13,300).
672
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
Fig. 8 (Dark and Streeten). Case 1. Anterior subcapsular cortex. Multilayered plasmalemmal membranes (x 142,200). Inset, Case 2. Whorls of cell membranes (x 162,700).
Mitochondrial swelling, seen in both our cases, may result from uncontrollable factors present in operating room speci mens. Many mitochondria, however, ap peared normal. There was no evidence of proliferation of the inner walls, or of crystalloid change in the mitochondria as noted by Kuwabara and Lessel 8 in muscle. The subcapsular lens cortex contains vacuoles with whorls of multilayered membranes (Fig. 7). The larger vacuoles correspond in size, frequency, and distri bution with the iridescent particles ob served by biomicroscopy, and are their presumed basis. Although similar struc tures may occasionally be seen in senile cortical and subcapsular cataracts of other
types, both in the slit-lamp beam and in electron micrographs, the profusion of such particles in transparent cortex is characteristic of myotonic lenses. Within the same cortical zone are linear intercel lular plasmalemma-like figures (Fig. 8) reminiscent of the septilaminar junctions (nexus) regularly seen in the normal cor tex 9 ; however, they contain many more layers. Similar laminations appear as arched forms that (Fig. 8, inset) are clear ly different from the "fingerprint bodies" seen intracellularly in muscle in some cases of myotonic dystrophy and other myopathies. 1 0 The derivation of these various laminated structures is unknown. They may indicate a primary disorder of cell membranes. Roses and Appel 1 1 ' 1 2
VOL. 84, NO. 5
CATARACT IN MYOTONIA
673
-|P#' ;r .,.' ->'
|,^v
^" :ΛΛ.'4-''^'*\-·.ΐ .■·.·
Fig. 9 (Dark and Streeten). Case 2. Concentric arrangement of multilaminate mem branes (x 139,000).
have provided biochemical evidence and scanning electron microscopic observa tions on muscle and erythrocytes to sup port the concept that mytonia dystrophica is a diffuse disorder of cell membranes. On the other hand, these multilayered membranes could simply represent a non specific sequel to cell degeneration. 7 The high reflectance of the colored par ticles and the constancy of their chromat ic values over a wide arc of incidence is perhaps best explained on the basis of multiple, thin layer interference, rather than b y other mechanisms (absorption, refractions, diffraction gratings, and scat tering) that are capable of producing structural coloration. The ideal optical conditions for iridescence, based on this
principle, are found when the layers have optical thickness (actual thickness x re fractive index) equal to one quarter of the wavelength of light. 13 The refractive indi ces of the various whorled lamellae seen in the anterior cortex of these two patients are unknown. However, some of the thicker lamellae approximate in thickness those seen in other iridescent biological structures. 1 4 Histochemical analysis was not undertaken in this study, but there was no electron microscopic evidence of cholesterol or other crystals to account for polychromasia of the particles. 3 SUMMARY
We examined cataracts from two pa tients with myotonia dystrophica by light
674
AMERICAN JOURNAL OF OPHTHALMOLOGY
microscopy and transmission electron mi croscopy. An excessive number of fibril lar inclusions were present in both lens capsules. The subcapsular epithelium re vealed watery vacuoles, an increased number of lipid droplets, and occasional pyknotic cells. The characteristic irides cent particles in the deep subcapsular zone correlated with vacuoles containing whorls of multilaminated membrane. The polychromatic display appeared to be a multilayer interference phenomenon from these membranes, rather than a crys talline effect from cholesterol crystals as previously suggested. REFERENCES 1. Duke-Elder, S.: Diseases of the Lens. In Sys tem of Ophthalmology, vol. 11. London, Henry Kimpton, 1969, p. 186. 2. Berliner, M. L.: Biomicroscopy of the Eye, vol. 2. Hoeber, New York, 1949, p. 1189. 3. Van den Heuvel, J. E. A.: in discussion of Vos, T.A.: 25 years of dvstrophica myotonia. Ophthalmologica 141:44, 196Ï. 4. Dark, A. J., Streeten, B. W., and Jones, D.: Accumulation of fibrillar protein in the aging human lens capsule. Arch. Ophthalmol. 82:815, 1969.
NOVEMBER, 1977
5. Seland, J. H.: Ultrastructural changes in the normal human lens capsule from birth to old age. Acta Ophthalmol. 52:688, 1974. 6. Finnean, J. B., Coleman, R., and Micheli, R. H.: Membranes and Their Cellular Functions. Ox ford, Blackwell, 1974, pp 60-63. 7. Trump, B. F., and Arstila, A. U.: Cel lular reaction to injury. In LaVia, M. F., and Hill, R. B. (eds.) Principles of Pathobiology, 2nd ed. New York, Oxford University Press, 1975, pp. 9-96. 8. Kuwabara, T., and Lesseil, S.: Electron micro scopic study of extraocular muscles in myotonia dystrophy. Am. J. Ophthalmol 82:303, 1976. 9. Phillipson, B. T., Hanninen, L., and Balazs, E, A.: Cell contacts in human and bovine lenses. Exp. Eye Res. 21:205, 1975. 10. Tome, F. M. S., and Fardeau, M.: Fingerprint inclusions in muscle fibres in myotonia dystrophica. Acta Neuropathol. 24:62, 1973. 11. Roses, A. D., and Appel, S. H.: Muscle mem brane protein kinase in myotonic muscular dystro phy. Nature 250:245, 1974. 12. Appel, S. H., and Roses, A. D.: Membrane biochemical studies in myotonic dystrophy in mem branes and disease. In Bolis, L., and Hoffman, J. F. (eds.): Membranes and Disease. New York, Leaf A. Raven Press, 1976. 13. Land, M. F.: The physics and biology of animal reflectors. Prog. Biophys. Mol. Biol. 24:75, 1972. 14. Lythgoe, J. N.: The structure and function of iridescent corneas in teleost fishes. Proc. R. Soc. Lond. 188:437, 1975.
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
ULTRASTRUCTURAL STUDY OF CATARACT IN MYOTONIA DYSTROPHICA ANTHONY J. DARK, M.D., AND BARBARA W. STREETEN, M.D. Syracuse, New York
Characteristic iridescent particles de velop in a narrow zone of the lens cortex in most patients suffering from myotonia dystrophica. The particles seen in optical section are separated by a clear zone of discontinuity from the anterior and pos terior capsules. They do not interfere with vision. In some patients, however, they are followed by the development of pos terior subcapsular opacities that are ophthalmoscopically visible as stellate cata racts. Opacification of the entire lens may develop as the final stage.1'2 Structural studies on cataract myotonia dystrophica have been inconclusive and confined to light microscopy.3 Two re cently obtained myotonic cataracts have enabled us to undertake electron micro scopic studies.
removed with cryoprobes after the appli cation of chymotrypsin. The lens from the patient in Case 1 was placed in 10% formalin, the lens from the second patient was fixed in ice cold 2.5% glutaraldehyde in phosphate buffer at pH 7.2. Half of the formalin-fixed lens was processed in par affin for routine histology. Free slices were examined by polarization micros copy. Pieces of capsule and underlying cortex were taken from both lenses and osmified and then embedded in an epoxy resin. One-micron sections were stained with toluidine blue and studied by light microscopy. Ultrathin sections were treat ed with uranyl acetate and lead citrate before examination by transmission elec tron microscopy.
SUBJECTS AND METHODS
Abnormal findings were present in the lens capsule, anterior subcapsular epithe lium, and the lens cortex. Light microscopy—Numerous capsular inclusions, similar to those seen in aging lenses, were visible in the pre-equatorial zone. Fine vertical striae were present in the deep portion of the capsule in this zone. The anterior subcapsular epithe lium had clear vacuoles, which were espe cially numerous in Case 1 but scarce in Case 2. The deep subcapsular cortex con tained minute vacuolated ovoid bodies, most of which were 6 to 15 μ long; a few reached 35 μ (Fig. 1). They corresponded in size and distribution with the irides cent particles seen biomicroscopically. In polarized light these bodies exhibited a characteristically variegated, spiral birefringance (Fig. 1, inset). The posterior subcapsular and cortical changes do not differ from those seen in senile cataracts. Electron microscopy—Embedded in
Two unrelated patients with classic myotonic dystrophy underwent cataract extraction; we used the two lenses in this study. A 54-year-old white woman (Case 1), and a 61-year-old white man (Case 2) had been examined by slit-lamp mi croscopy preoperatively. In both patients, approximately symmetrical lens changes included the presence of a deep subcapsu lar zone of iridescent particles together with posterior subcapsular and minimal cortical cataract. The lenses were From the Department of Ophthalmology, Veter ans Aministration Hospital (Dr. Dark); and the De partments of Ophthalmology (Drs. Dark and Streeten) and Pathology (Dr. Streeten), Upstate Medical Center, Syracuse, New York. This study was supported in part by the Medical Research Service of the Veterans Administration and by Re search Grant EY 01602 from the National Eye Institute. Reprint requests to Anthony J. Dark, M.D., De partment of Ophthalmology, Veterans Administra tion Hospital, Syracuse, NY 13210.
RESULTS
VOL. 84, NO. 5
CATARACT IN MYOTONIA
Fig. 1 (Dark and Streeten). Case 1. Unstained lens slice showing vacuolated oval bodies (arrows) in deep subcapsular zone (x50). Inset shows spiral configuration of single body (xllO).
the pre-equatorial capsules were numer ous filament-containing inclusions (Fig. 2). The filaments, which were 8 to 12 nm wide, appeared as hollow tubes in cross section (Fig. 3). They showed occasional banding at 50 nm. The deep capsular striae seen with the light microscope were columns of cytoplasmic material extend ing vertically outward from the bases of subjacent epithelial cells (Fig. 4). The proximal portion of these columns con-
667
tained a cell process, but the more distal part was often occupied by cytoplasmic granules and capsular filaments (Fig. 4, inset). The deep layer of the capsule showed multilaminar basement mem brane formation parallel to the capsular surface except where it was oriented alongside cytoplasmic processes and granules. In all regions, the subcapsular epithe lium showed a variable number of mem brane bound vacuoles. In Case 1 these changes were so marked that they appar ently represented artifacts. Occasional shrunken electron-dense cells were pres ent in this layer, sometimes surrounded by live cells (Fig. 5). Mitochondria showed high amplitude swelling (Fig. 5). Lipid droplets were seen regularly in many of the epithelial cells (Fig. 6). In occasional cells were crystalloid accumu lations of protein. (Fig. 6). Scattered through the anterior lens cor tex were numerous vacuoles containing whorls of multilaminated membranes (Fig. 7). The larger vacuoles correspond ed in size, number, and distribution with
Fig. 2 (Dark and Streeten). Case 1. Pre-equatorial lens capsule contains numerous filamentous inclusions. Elongated cytoplasmic processes (E) of the adjacent epithelium extend into the deep layer of capsule (x 17,300).
668
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
Fig. 3 (Dark and Streeten). Case 2. Detail of pre-equatorial capsule shows tubular appearance of filaments in cross section (x62,700).
the biréfringent ovoid bodies observed in light microscopy. The laminae exhibited uniform thickness and staining properties within a given vacuole, but varied consid erably in width (2 to 70 nm) and electron density in different vacuoles. Some vacu oles contained only granular, electrondense material. Arrays of reduplicated plasmalemmalike membranes, 2 nm wide, were also found in the anterior cortex. They were between lens fibers and appeared as par allel, slightly wavy lines (Fig. 8), or in arched configurations (Fig. 8, inset). Con centric arrangements (Fig. 9) of similar membranes were also seen in this region. The posterior subcapsular and cortical opacities revealed globular degeneration
of lens fibers and other nonspecific cataractous changes. DISCUSSION
Capsular inclusions containing fibrillar protein are an almost universal finding in aging lenses. 4,5 They are particularly abundant in pseudoexfoliative disease. Little is known of their significance, ex cept that they resemble zonular protein and may be synthesized by the underly ing epithelial cells. 4 The profusion of capsular inclusions present in both pa tients was greater than we have seen in senile cataract, either with or without pseudoexfoliation. The stimulus for their excess in myotonia dystrophica is un known. The presence of elongated epithelial
CATARACT IN MYOTONIA
VOL. 84, NO. 5 iJv;
Di
tuta ,'0 ^ 'iftî.i;
M
Fig. 4 (Dark and Streeten). Case 2. Pre-equatorial lens capsule. Vertical columns (G) contain cytoplasmic granular material and filaments (x 7,500). Inset shows cell processes at base of column (x 10,000).
669
670
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
*>*
'■'".■fS-'Ì;i
És& •'■».A,-',,,
,
.
Fig. 5 (Dark and Streeten). Case 2. Anterior lens epithelium. Dead cell surrounded by live epithelial cell; capsule (C); mitochondria (M) showing segmental distension (x 12,500).
cell processes extending into the deeper layers of the pre-equatorial capsule is also not specific for myotonia dystrophica. Seland 5 noted them in the postequatorial capsule in patients as young as 17 years old, and we have observed them in the pre-equatorial capsule in pseudoexfoliative disease. The presence of cytoplasmic granules outside the cell membrane of these processes is difficult to interpret. It may represent exocytosis, 6 or result from
degenerative changes in the cell proc esses. The subcapsular epithelial cells showed changes indicative of chronic in jury, including lipid droplets, watery vacuolations of the cytoplasm, and cell death. 7 Oil droplets were also a feature of the sarcoplasmic changes observed by Kuwabara and Lessel 8 in extraocular muscle of patients with myotonia dystro phica.
VOL. 84, NO. 5
CATARACT IN MYOTONIA
'*:'■ **■ -I
': V / ;
671
-j»;
Üfe&
i/Äi^'
Fig. 6 (Dark and Streeten). Case 2. Anterior lens epithelium showing lipid droplets (x29,600). Inset illustrates a protein crystalloid (x21,800).
Fig. 7 (Dark and Streeten). Case 1. Anterior subcapsular cortex. Larger (12μ) vacuole containing multilaminar whorls (x 13,300).
672
AMERICAN JOURNAL OF OPHTHALMOLOGY
NOVEMBER, 1977
Fig. 8 (Dark and Streeten). Case 1. Anterior subcapsular cortex. Multilayered plasmalemmal membranes (x 142,200). Inset, Case 2. Whorls of cell membranes (x 162,700).
Mitochondrial swelling, seen in both our cases, may result from uncontrollable factors present in operating room speci mens. Many mitochondria, however, ap peared normal. There was no evidence of proliferation of the inner walls, or of crystalloid change in the mitochondria as noted by Kuwabara and Lessel 8 in muscle. The subcapsular lens cortex contains vacuoles with whorls of multilayered membranes (Fig. 7). The larger vacuoles correspond in size, frequency, and distri bution with the iridescent particles ob served by biomicroscopy, and are their presumed basis. Although similar struc tures may occasionally be seen in senile cortical and subcapsular cataracts of other
types, both in the slit-lamp beam and in electron micrographs, the profusion of such particles in transparent cortex is characteristic of myotonic lenses. Within the same cortical zone are linear intercel lular plasmalemma-like figures (Fig. 8) reminiscent of the septilaminar junctions (nexus) regularly seen in the normal cor tex 9 ; however, they contain many more layers. Similar laminations appear as arched forms that (Fig. 8, inset) are clear ly different from the "fingerprint bodies" seen intracellularly in muscle in some cases of myotonic dystrophy and other myopathies. 1 0 The derivation of these various laminated structures is unknown. They may indicate a primary disorder of cell membranes. Roses and Appel 1 1 ' 1 2
VOL. 84, NO. 5
CATARACT IN MYOTONIA
673
-|P#' ;r .,.' ->'
|,^v
^" :ΛΛ.'4-''^'*\-·.ΐ .■·.·
Fig. 9 (Dark and Streeten). Case 2. Concentric arrangement of multilaminate mem branes (x 139,000).
have provided biochemical evidence and scanning electron microscopic observa tions on muscle and erythrocytes to sup port the concept that mytonia dystrophica is a diffuse disorder of cell membranes. On the other hand, these multilayered membranes could simply represent a non specific sequel to cell degeneration. 7 The high reflectance of the colored par ticles and the constancy of their chromat ic values over a wide arc of incidence is perhaps best explained on the basis of multiple, thin layer interference, rather than b y other mechanisms (absorption, refractions, diffraction gratings, and scat tering) that are capable of producing structural coloration. The ideal optical conditions for iridescence, based on this
principle, are found when the layers have optical thickness (actual thickness x re fractive index) equal to one quarter of the wavelength of light. 13 The refractive indi ces of the various whorled lamellae seen in the anterior cortex of these two patients are unknown. However, some of the thicker lamellae approximate in thickness those seen in other iridescent biological structures. 1 4 Histochemical analysis was not undertaken in this study, but there was no electron microscopic evidence of cholesterol or other crystals to account for polychromasia of the particles. 3 SUMMARY
We examined cataracts from two pa tients with myotonia dystrophica by light
674
AMERICAN JOURNAL OF OPHTHALMOLOGY
microscopy and transmission electron mi croscopy. An excessive number of fibril lar inclusions were present in both lens capsules. The subcapsular epithelium re vealed watery vacuoles, an increased number of lipid droplets, and occasional pyknotic cells. The characteristic irides cent particles in the deep subcapsular zone correlated with vacuoles containing whorls of multilaminated membrane. The polychromatic display appeared to be a multilayer interference phenomenon from these membranes, rather than a crys talline effect from cholesterol crystals as previously suggested. REFERENCES 1. Duke-Elder, S.: Diseases of the Lens. In Sys tem of Ophthalmology, vol. 11. London, Henry Kimpton, 1969, p. 186. 2. Berliner, M. L.: Biomicroscopy of the Eye, vol. 2. Hoeber, New York, 1949, p. 1189. 3. Van den Heuvel, J. E. A.: in discussion of Vos, T.A.: 25 years of dvstrophica myotonia. Ophthalmologica 141:44, 196Ï. 4. Dark, A. J., Streeten, B. W., and Jones, D.: Accumulation of fibrillar protein in the aging human lens capsule. Arch. Ophthalmol. 82:815, 1969.
NOVEMBER, 1977
5. Seland, J. H.: Ultrastructural changes in the normal human lens capsule from birth to old age. Acta Ophthalmol. 52:688, 1974. 6. Finnean, J. B., Coleman, R., and Micheli, R. H.: Membranes and Their Cellular Functions. Ox ford, Blackwell, 1974, pp 60-63. 7. Trump, B. F., and Arstila, A. U.: Cel lular reaction to injury. In LaVia, M. F., and Hill, R. B. (eds.) Principles of Pathobiology, 2nd ed. New York, Oxford University Press, 1975, pp. 9-96. 8. Kuwabara, T., and Lesseil, S.: Electron micro scopic study of extraocular muscles in myotonia dystrophy. Am. J. Ophthalmol 82:303, 1976. 9. Phillipson, B. T., Hanninen, L., and Balazs, E, A.: Cell contacts in human and bovine lenses. Exp. Eye Res. 21:205, 1975. 10. Tome, F. M. S., and Fardeau, M.: Fingerprint inclusions in muscle fibres in myotonia dystrophica. Acta Neuropathol. 24:62, 1973. 11. Roses, A. D., and Appel, S. H.: Muscle mem brane protein kinase in myotonic muscular dystro phy. Nature 250:245, 1974. 12. Appel, S. H., and Roses, A. D.: Membrane biochemical studies in myotonic dystrophy in mem branes and disease. In Bolis, L., and Hoffman, J. F. (eds.): Membranes and Disease. New York, Leaf A. Raven Press, 1976. 13. Land, M. F.: The physics and biology of animal reflectors. Prog. Biophys. Mol. Biol. 24:75, 1972. 14. Lythgoe, J. N.: The structure and function of iridescent corneas in teleost fishes. Proc. R. Soc. Lond. 188:437, 1975.