Yonago Acta medica 1997;40:91–96

Morphological Changes in Patient Lens Epithelial Cells after Intravitreal
Silicone Oil Injection
Shigeru Takagi, Masao Nagata, Yukiko Ametani, Atsushi Yamasaki, Chiemi
Itamochi and Akihiko Tamai
Department of Ophthalmology, Faculty of Medicine, Tottori University, Yonago 683, JapanThe subject patient (47-year-old male) had received silicone oil injection into the vitreous
cavity of his left eye for the treatment of retinal detachment in 1986. Two months later,
the silicone oil was removed from the vitreous cavity, as the retina was reattached.
Soon after the operation, the lens of the eye gradually became opaque to mature cataract,and his left visual acuity had fallen to hand motion upon his present admission to thehospital. The lens epithelium obtained by anterior capsulotomy during the extracapsularcataract extraction was examined morphologically by transmission electron microscopy.
Inside the anterior lens capsule, abnormal epithelial proliferation was observed. The
epithelial cells changed their shapes from cuboidal to spindle, accompanied by new
basal lamina-like substances around them. The spindle-shaped cells stretched likepseudopodia. The extracellular matrices were abundant and composed of collagenfibers. Fragments and dissolved materials of the fibers were also seen in some specimens.
Lipid-like substances and myelin-like structures were often observed in the relatively
well preserved cytoplasm. As a result, it is surmised that cataract formation after
intravitreal silicone oil injection may be associated with fibrous pseudometaplasia ofthe lens epithelial cells and phagocytosed silicone oil deposits in the epithelial cells.
Key words: fibrous pseudometaplasia; intravitreal silicone oil injection; lens epithelial cells;
phagocytosed silicone oil deposits; transmission electron microscopy

Intravitreal silicone oil injection is effective intreating some types of retinal detachment in
human eyes (Armaly, 1962; Cibis et al., 1962;
Leaver et al., 1979; Ando, 1985, 1987; Casswell
and Gregor, 1987; Laqua et al., 1987; Oshio et al.,
1988; Ozaki et al., 1993). It is, however, known
to cause various complications, such as cataract,
band-shaped keratopathy, intraocular hypertension, retinal toxicity, optic nerve atrophy, andso forth (Leaver et al., 1979; Scott, 1982; Ando,
1985, 1987; Casswell and Gregor, 1987; Laquaet al, 1987; Oshio et al., 1988; Ozaki et al.,1993). Among these, complicated cataract
formation is considered to be almost unavoidable (Leaver et al., 1979; Ando, 1985, 1987;
Casswell and Gregor, 1987; Oshio et al., 1988).
To date, however, there have been few basic
Abbreviation: ECCE, extracapsular cataract extraction

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studies on lens opacity caused by intravitreal
silicone oil injection in animal or human eyes
(Kishimoto and Mori, 1966; Leaver et al., 1979;
Scott, 1982; Yamasaki et al., 1994).
In the present study, morphological changes
in patient lens after intravitreal silicone oil injection were examined by transmission electron
microscopy.

Patient and Methods

Patient
The subject patient (47-year-old male) was
originally admitted to a private hospital in
Nagoya, Japan, in March 1963 with idiopathic
retinal detachment in the left eye associatedwith equatorial lattice degeneration with small

S. Takagi et al.

Fig. 1. The patient’s left eye showing mature cataract
upon his present admission to the hospital.

opacity in the left eye. The lens opacified
gradually to mature cataract (Fig. 1), and hiscorrected visual acuity in the left eye fell tohand motion. On June 15, 1995, he was referred to our department for adequate treatment of the cataract and admitted to the
Tottori University Hospital on the same day.
On June 19, 1995, extracapsular cataract extraction (ECCE) and intraocular lens implantation were performed in the left eye.
During the surgery, the anterior and posterior lens capsules were found intact. Postoperatively the visual acuity improved to 0.1
in the left eye.

holes. The following day heunderwent a buckling procedure
with local explant and cryotherapy
with subsequent retinal reattachment. In July 1986, however, retinal detachment recurred in the left
eye, with evidence of vitreoretinal
traction after the initial surgery.
On July 28, 1986, vitreous gel andvitreoretinal, tractional strands
were vitrectomized and about 3.5
mL of silicone oil (1000 centistokes, Dow Corning, Midland, MI)
was injected into the retrohyaloid
space via the pars plana. The retina was reapposed to the pigment
epithelium, so 2 months later thesilicone oil was removed from thevitreous cavity. At the time, his
corrected visual acuity in the left
eye was 0.2 and the intraocularpressure was 15.0 mmHg.
Soon after the operation, however, he noticed misty vision in theleft eye. An ophthalmologist whom
he consulted, pointed out lensFig. 2 (upper). Abnormal epithelial proliferation is seen inside the anterior lens capsule.
Fig. 3 (lower). A spindle-shaped lens epithelial cell is seen, accompanied by new basal lamina-like
substances (arrowheads) around the cell.

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Lens changes afer silicone oil injection

Methods
The lens epithelium was obtainedby anterior capsulotomy using the
can-opener technique at the ECCE.
The material was immediately
fixed in 10% buffered formalin andcut into 2 pieces. The specimens
were rinsed overnight in 0.1 M
cacodylate buffer containing 7.5%
sucrose followed by postfixation
with 1% osmium tetroxide for 1.5
h. After block-staining in 1% uranyl acetate, they were dehydrated
in a graded series of ethanols andfinally embedded in Epon. Ultrathin sections were obtained using a
diamond knife and an ultramicrotome (Type MT 6000-XT, RMC,
Tucson, AZ) and examined with atransmission electron microscope(Type H-7100, Hitachi, Tokyo,
Japan) at 75 kV after doublestaining with uranyl acetate ortannic acid and lead citrate.

Results
Inside the lens capsule in theanterior polar region, abnormal
epithelial proliferation was observed by transmission electron
microscopy (Fig. 2). The epithelial
cells changed their shapes from
cuboidal to spindle, accompaniedby new basal lamina-like substances around them (Fig. 3). The
spindle-shaped cells stretched likepseudopodia (Fig. 4). The extracellular matrices were abundant(Fig. 5) and composed of collagenfibers (Fig. 6). The collagen fibers

Fig. 4 (upper). A spindle-shaped lens epithelial cell (arrow) stretches like a pseudopodium.
Fig. 5 (middle). Extracellular matrices (asterisks) are abundant.
Fig. 6 ( lower). Extracellular matrices are composed of collagen fibers.

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S. Takagi et al.

al., 1979; Yamasaki et al., 1994)
of the subject patient’s lens could
not be disregarded. It is, however,uncertain how silicone oil removal
in the present case influenced thelens itself or intraocular surroundings around the lens, since thesurgical manipulation and slitlamp biomicroscopic findings ofthe lens in those days are now unknown.
Few reports have been published on electron microscopical observation of the human lens epithelial cells after silicone oil injection (Leaver et al., 1979). By elecFig. 7. Collagen fibers consist of microfibrils with a period oftron microscopy, Leaver and coabout 50 nm.
workers (1979) demonstrated
phagocytic cells with large vacuconsisted of microfibrils with a period of about olar inclusions, which were presumed to
50 nm (Fig. 7). Fragments and dissolved mate- represent engulfed silicone oil attached to therials of the fibers were also seen in some speci- anterior lens capsule, in their specimen obtainmens (Fig. 8). The other morphological find- ed from a human eye enucleated due to severe
ings showed lipid-like substances full of equal late complications caused by silicone oilamounts of liquid and myelin-like structures injection. The capsule, basement membrane
often existing in the relatively well preserved and epithelium of the lens, however, showed noevidence of infiltration by the oil. As a result,cytoplasm of the epithelial cells (Fig. 9).
they suggested that the complicated cataract
due to silicone oil injection was probably
Discussion
caused not by any toxic effect of silicone oil,The occurrence of lens opacities,
or their progression, is common
after the removal of silicone oil,even after a short tamponade of a
few weeks, as in the present case(Ando, 1985, 1987; Casswell and
Gregor, 1987; Oshio et al., 1988).
Thus, the effects of the mechanicalstress to the lens (Casswell and
Gregor, 1987; Laqua et al., 1987;
Ozaki et al., 1993) or exposure of
the lens to silicone oil during
surgery (Armaly, 1962; Kishimotoand Mori, 1966; Ando, 1985;
Casswell and Gregor, 1987; Laquaet al., 1987) and/or obstruction of
normal metabolic exchange at thesilicone-tissue interface (Leaver etFig. 8. Fragments and dissolved materials of the collagen fibers areseen in this specimen.

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Lens changes afer silicone oil injection

replaced by a thick layer of fibrous
tissue. Both morphological findings revealed fibrous pseudometaplasia of the lens epithelial
cells. As a result, it is surmisedthat cataract formation after intravitreal silicone oil injection may
be associated with such a fibrouspseudometaplasia of the lens epithelial cells.
In our previous study using
adult albino rabbits (Yamasaki etal., 1994), transmission electron
microscopical examination revealed that the cytoplasm of the lensepithelial cells, adjacent to theFig. 9. Lipid-like substances (arrows) and a myelin-like structureinterdigitation, began to show a(arrowhead) are seen in the relatively well preserved cytoplasm ofvesicle-like structure 2 weeks after
the lens epithelial cell.
intravitreal silicone oil injection.
This vesicle-like structure resembut by obstruction of normal metabolic ex- bled a micropinocytotic vesicle derived fromadsorptive micropinocytosis (Fawcett, 1981).
change at the silicone-tissue interface.
In the present study in which attention was This structure was absent in the control eyes
paid to the morphological changes in the pa- even 3 months after surgery. Therefore, thistient’s lens after intravitreal silicone oil injec- structure seemed to be associated with siliconetion, the above characteristic finding was not oil, although no signs indicating direct intake ofobserved in the lens epithelial cells in the ante- silicone oil into the lens were observed in therior polar region. Inside the anterior lens cap- previous study. It was presumed that suchsule, however, abnormal epithelial proliferation damage to the lens epithelial cells might affectwas observed by transmission electron micros- the onset and development of lens opacity.
This unique vesicle-like structure was notcopy. The epithelial cells changed their shapes
from cuboidal to spindle, accompanied by new detected in the present study, but it is of notebasal lamina-like substances around them, and that lipid-like substances full of equal amounts
the spindle-shaped cells stretched like pseudo- of liquid and myelin-like structures were often
podia, which resemble fibrocytes. Further- observed in the relatively well preserved cytomore, the extracellular matrices were abundant plasm of the epithelial cells. This shows theand composed of collagen fibers consisting of possibility of the intake of silicone oil particles
microfibrils with a period of about 50 nm, into the lens in parallel with the obstruction ofwhich are derived from a metaplastic change in normal metabolic exchange at the siliconethe lens epithelium itself. Fragments and dis- tissue interface (Leaver et al., 1979), althoughsolved materials of the fibers also were detected no signs indicating direct intake of silicone oil
into the lens epithelial cells through the anterior
in some specimens.
These findings were almost consistent with lens capsule were observed even in the subject
those obtained by Scott’s light microscopic patient with mature cataract.
The relatively well preserved cytoplasm ofstudy on the lens which had received intravitreal silicone oil injection after surgical treat- the lens epithelial cells indicates that absorbed
ment of retinal detachment (Scott, 1982). He or phagocytosed silicone oil particles do not
observed the excised anterior lens capsules, and inflict toxic damage to the epithelial cells, as
the anterior epithelium was found to have been intravitreal silicone oil itself is originally con95

S. Takagi et al.

3 Armaly MF. Ocular tolerance to silicones. Arch
Ophthalmol 1962;68:390–395.
4 Casswell AG, Gregor ZJ. Silicone oil removal. I.
The effect on the complications of silicone oil.
Br J Ophthalmol 1987;71:893–897.
5 Cibis PA, Becker B, Okun E, Canaan S. The useof liquid silicone in retinal detachment surgery.
Arch Ophthalmol 1962;68:590–599.
6 Fawcett DW. The cell. 2nd ed. Philadelphia:
WB Saunders, 1981:108–110.
7 Kishimoto M, Mori S. A long-term observationof intravitreal injection of silicone fluid into
rabbit eyes. Nippon Ganka Kiyo 1966;17:71–76(in Japanese with English abstract).
8 Laqua H, Lucke K, Foerster M. Results ofsilicone oil surgery. Jpn J Ophthalmol 1987;31:
124–131.
9 Leaver PK, Grey RHB, Garner A. Silicone oil
injection in the treatment of massive preretinal
retraction: I. Late complications in 93 eyes. Br J
Ophthalmol 1979;63:361–367.
10 Oshio Y, Oshima K, Kurata Y. Complications of
intravitreal silicone oil and their management.
Rinsho Ganka 1988;42:1083-1087 (in Japanesewith English abstract).
11 Ozaki H, Shinya Y, Hayashi H, Ohshima K.
Visual functions in a case of removal of intravitreal silicone oil retained for ten years. Ganka
Rinsho Iho 1993;87:1913–1916.
12 Scott JD. Lens epithelial proliferation in retinal
detachment. Trans Ophthalmol Soc UK 1982;
102:385–389.
13 Stone W Jr. Alloplasty in surgery of the eye.
New Engl J Med 1958;258:486–490.
14 Yamasaki A, Nagata M. Takagi S, Tamai A.
Time-course of lens opacity and morphologicalchanges in rabbit lens epithelial cells after intravitreal silicone oil injection. Jpn J Ophthalmol
1994;38:116–122.

sidered to be harmless (Stone, 1958). However,
we cannot deny entirely the possibility ofcataract formation after intravitreal silicone oil
injection caused by chronic metabolic disturbances (Scott, 1982) in the presence of phagocytosed silicone oil deposits in the cytoplasm.
In conclusion, our findings suggest that theobserved changes in the lens epithelial cells
represent cytoplasmic and/or metabolic dysfunctions in the cells, and that these changes areclosely related to the onset of lens opacity andits progression following intravitreal silicone
oil injection. As regards the silicone oil intake
into the lens, further observation is needed incases of removal of intravitreal silicone oilretained for a longer period than in the present
case.
Acknowledgments: The authors wish to thank Prof.
Takao Inoué of the Second Department of Anatomy,
Faculty of Medicine, Tottori University, for his kindadvice and valuable suggestions in this study.

References
1 Ando F. Complications of intraocular silicone
and their possible treatment. In: Mizuno K, ed.
Ophthalmology, International Congress Series
671. Amsterdam: Excerpta Medica, 1985:124–
130.
2 Ando F. Usefulness and limit of silicone inmanagement of complicated retinal detachment.
Jpn J Ophthalmol 1987;31:138–146.

(Received April 16, Accepted April 24, 1997)

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