Silicone oil use as an adjunct to complicated vitreoretinal surgery
is becoming more frequent. Refractory glaucoma in these patients is common.
Isolated reports have mentioned the possibility of silicone oil migrating
and/or obstructing the tube in the anterior chamber of Molteno implants (IOP,
Costa Mesa, Calif).1,2 This
report describes a case of intraocular silicone oil egressing through an Ahmed
implant (New World Medical, Rancho Cucamonga, Calif), impairing the functioning
of the tube and requiring replacement of the implant plus oil removal. We
present photographic documentation of the oil progressing through the tube
and histopathologic analysis of the orbital tissue surrounding the extruded
A 69-year-old white man lost his left eye to trauma at age 12 years.
In September 2000, blunt trauma resulted in a lacerated eyebrow, scleral rupture,
uveal prolapse, extrusion of his crystalline lens, retinal detachment, and
suprachoroidal hemorrhage in his right eye. A limited anterior chamber washout
was performed at the time of the primary repair. Ten days later, he underwent
pars plana vitrectomy, silicone oil injection, and a scleral buckle. A pars
plana vitrectomy revision with endolaser, membrane stripping, and silicone
oil reinjection were performed 1 month later for a recurrent retinal detachment.
In January 2001, glaucoma surgery was needed to control elevated intraocular
pressure (IOP). The eye was aphakic and had total traumatic aniridia. An Ahmed
valve was implanted inferonasally in an attempt to avoid the silicone oil
bubble (Figure 1 and Figure 2). The patient's IOP responded well initially but rose subsequently
to 30 mm Hg. A bubble of silicone oil was wrapping the tip of the tube (Figure 3). Silicone oil could be seen migrating
through the Ahmed tube (Figure 4
and Figure 5) and the bleb over
the implant progressively enlarged and appeared encapsulated during the next
few months. A glistening material was noted in cystic spaces overlying the
Ahmed implant under the conjunctiva. An inferior ectropion that progressed
gradually was also noted. The volume of the silicone bubble in the vitreous
cavity decreased from an estimated 85% fill to an estimated 50% fill. Ectropion
repair was necessary in June 2001.
Slitlamp photograph showing the
Ahmed tube inferonasally short after implantation. Notice total traumatic
aniridia and superotemporal paralimbal scleral wound with interrupted sutures.
Retroillumination photograph showing
a patent Ahmed tube.
Slitlamp photograph showing "candle
wax" appearance of the silicone oil wrapped around the tip of the Ahmed tube.
Retroillumination photograph showing
a level of silicone oil (arrow) inside the Ahmed tube.
Retroillumination photograph taken
on a different day shows a different level of silicone oil (arrow) inside
the Ahmed tube.
Owing to persistently elevated IOP measurements, transcorneal removal
of the silicone oil combined with replacement of the Ahmed implant was performed.
Multiple silicone oil–filled conjunctival cysts were found surrounding
the Ahmed plate. A tissue sample was taken inferotemporally from a thick capsule
surrounding the Ahmed implant. Histopathologic analysis of the tissue surrounding
the plate demonstrated fibroconnective tissue with numerous small vacuoles.
Surrounding this tissue were numerous foreign-body giant cells and histiocytes
Histopathologic examination of
orbital tissue excised during removal of valve shows empty vacuoles consistent
with silicone oil and larger deposit of oil surrounded by epithelioid histiocytes
and foreign body giant cells (hematoxylin-eosin, original magnification ×200).
To our knowledge, this is one of the first documented cases of silicone
oil exiting the eye through an Ahmed implant. Review of the literature yielded
2 previous reports, both involving Molteno implants in aphakic patients1,2 and 1 recent report involving
an Ahmed implant.3 Minckler4
describes adhesion of the silicone oil to the anterior chamber portion of
the drainage tube, resembling candle wax, without lumen obstruction. He recommends
placing the tube in an inferior location to minimize the chance of oil-tube
obstruction. In our case, the inferior location of the tube did not prevent
the migration of the silicone oil through the Ahmed implant. The inflammatory
reaction observed in the periocular tissues, apparently caused by the silicone
oil, has been documented before.1,2
This contrasts with no observed clinical reaction in intraocular tissues,
although histopathologically foreign-body granulomas have been documented
in intraocular tissues.
The silicone oil did impair the drainage of aqueous through the implant
as evidenced by the elevated IOPs. Encapsulation of the bleb might also have
contributed to the obstruction of the implant. The photographs (Figure 3 and Figure 4),
showing oil at different levels of the tube, demonstrate the progression of
the silicone oil through the tube of the Ahmed implant. We believe that aphakia
with total aniridia resulted in an anatomic situation (a truly unicameral
eye) that favored the anterior migration of the silicone oil when the patient
inadvertently assumed a supine position. This was probably favored by the
well-known physical attraction of the silicone tube toward the silicone oil.
Once an oil bubble made it to the entrance of the tube, the combined effect
of capillary action with elevated IOP may have facilitated the migration of
the oil to the subconjunctival space. The patient's IOP has been under control
since replacement of the Ahmed implant and removal of the silicone oil. His
last corrected visual acuity was 20/50 OD.
It seems that a "unicameral" eye with silicone oil, particularly with
significant iris defects, is a poor candidate for successful IOP control with
a seton in a 1-stage procedure. In our case, the inferior location of the
implant did not prevent silicone oil movement out of the eye with secondary
impairment of IOP control. Silicone oil removal needs to be considered prior
to implantation of a seton in such cases. If silicone oil removal is not an
option, diode laser cyclophotocoagulation is another alternative for IOP control.
Corresponding author: Jose Morales, MD, Texas Tech University Health
Sciences Center, Department of Ophthalmology and Visual Sciences, 3601 Fourth
St, STOP 7217, Lubbock, TX 79430-7217 (e-mail: email@example.com).
Morales J, Shami M, Craenen G, Wentlandt TF. Silicone Oil Egressing Through an Inferiorly Implanted Ahmed Valve. Arch Ophthalmol. 2002;120(6):831-832. doi: