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Block excision therapy of choice
for epithelial in-growth
Stefanie
Petrou-Binder MD in Ludwigshafen, Germany
BLOCK excision is the therapy of choice for selected patients who
develop cystic epithelial in-growth following cataract surgery,
according to a new study presented at the Congress of the German-Speaking
Society for Intraocular Lens Implantation and Refractive Surgery
(DGII).
Researchers at the University Eye Clinic, Erlangen, Germany conducted
a retrospective review of 59 patients who had been diagnosed with
epithelial invasion between 1980 and 1997, following surgeries carried
out between 1971 and 1994. The 15 patients whose problems were associated
with cataract surgery then underwent block excision of the invading
epithelial cells with subsequent corneo-scleral transplantation.
"Cystic removal using careful block excision showed no recurring
epithelial in-growth up to seven years after surgery in patients
with cystic epithelial invasion of the anterior segment with chamber
angle involvement under five clock hours," Arne Viestenz MD
reported.
The time between the cataract surgery and the block excision averaged
seven years, ranging from one to 15 years. The mean patient age
was 65.
All patients were monitored for at least three years after the excision
surgery. None of the eyes operated on revealed any recurrence of
in-growing epithelial cells at any time throughout the follow-up
period. Six of the 15 eyes had a postoperative visual acuity of
0.1 or better.
The cyst was found in the upper part of the sclero-corneal tunnel
in 11 out of 15 cases. Two were nasally located and another two
were temporal. The mean cyst diameter was 2.4 ± 1 clock hours
and the limbal circumference was between one and four clock hours.
The intraoperative and postoperative complications included four
cases of vitreous bleeding and three cases of corneal endothelial
decompensation. One patient had both of these complications. There
was also one vascularised corneal scar and one hypotonic bulb.
German specialists GOH Naumann MD, assisted by M Küchle MD,
performed the block excision surgery utilising the technique. For
the cyst excision, the surgeon implements a sclera-adapted Flieringa
ring to stabilise the bulbus prior to the block excision. He then
performs a transcorneal or transscleral cyst puncture on the fixed
part of the cyst to reduce its volume.
The next step is an injection of a viscoelastic agent to force the
cyst into the anterior chamber. A manual trepan is used to excise
the involved corneal and scleral layers. Dr Viestenz noted that
extra care is required to gradually level off the corneal lamellae
and thereby keep as much healthy corneal tissue as possible.
Next, the surgeon carefully excises the involved areas of the ciliary
body and iris, allowing the requisite safety margin. Prof Naumann
and Prof Küchle were able to remove all of the cysts in this
series in toto. The block diameter of the excised cysts was 8.0
± 1.8mm. Finally, following an extensive anterior vitrectomy,
they implanted a corneo-scleral transplant in each case.
Overall incidence
Dr Viestenz noted that the overall incidence of cataract surgery-induced
epithelial invasion over the past two decades has dropped to an
all time low of 0.2%, thanks to improved surgical techniques.
This is a remarkable improvement considering that between 1950 and
1970, up to 27% of enucleated eyes involved epithelial invasion.
A histopathological study of 207 eyes with epithelial invasion carried
out in 1996 (M Küchle et al.) showed that 59% resulted from
cataract surgery.
Nonetheless, the problem still occurs on occasion. Complete chamber
angle closure can result from widespread epithelial cell growth
and subsequently be the cause of secondary chamber angle-block glaucoma
which may end in painful blindness, he stressed.
According to Dr Viestenz, a partial resection of the cyst is inadequate
because it leaves behind the epithelial cells which proliferate
along and throughout the trabecular meshwork. A partial chamber
angle block remains in these cases, along with a risk of complete
chamber angle blockage and diffuse epithelial cell dispersion to
still unaffected ocular tissues.
He
cited other studies confirming the disadvantages of opening epithelial
cysts using laser, as cells may then invade other ocular tissues
and transform the cystic nature of the epithelial invasion into
a diffuse form. An overview of the literature showed that between
33% and 100% of eyes which underwent laser puncture of the epithelial
cyst had recurrences within a short time.
Arne
Viestenz MD
University Eye Clinic, Erlangen, Germany
Email: Arne.Viestenz@t-online.de
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