Silicon oil into the AC. Late-onset IOP elevation can

Silicon oil is a frequently utilized adjunct
to surgical repair of complex retinal detachment. Glaucoma can complicate the post-operative
course of such procedures with incidence that varies between 2.2% and 56%1,2. Mechanism of intraocular pressure (IOP) elevation
can be from acute angle closure with or without pupillary block; open-angle
glaucoma with silicone oil in the anterior chamber; rubeosis irides leading to
secondary angle closure; or primary open-angle glaucoma.

Several risk factors for
development of IOP elevation have been studied previously but remained unclear.
These include preexisting glaucoma, diabetes, and aphakia3, silicone oil
in the anterior chamber; early postop pressure spike; trauma; and postop
neovascularization of the iris. Also, an association has been
found with the quantity of emulsified oil in the AC and the use of heavy
tamponading agents4

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

Several mechanisms of IOP elevation have been
proposed and are generally classified into early postoperative IOP elevation
and late-onset glaucoma. Early IOP elevation may be from preexisting glaucoma, pupillary
block, inflammation, and/or mechanical impediment to filtration caused by displaced
silicone oil into the AC. Late-onset IOP elevation can be caused by
infiltration of the trabecular meshwork by silicone bubbles, synechially closed
angle, iris neovascularization, and/or primary open angle glaucoma4.

Treatment strategy of silicone oil related
glaucoma should be based on the mechanism of IOP elevation. Topical
antiglaucoma medication coupled with cycloplegics and steroids may effectively lower
IOP in 30-78% of patients2,5. Eyes with silicone oil are at risk of
pupillary block glau. however, spontaneous closure of PI may occur in 11-32% of
cases and need to be reopened2,4,6.

Cyclophotoablation may be an alternative in
eyes at high risk of re-detachment after silicone oil removal, or in eyes with
poor visual potential. However, no data on success rate were reported in
literature.

 

Decision for therapeutic early silicon oil
removal is usually made difficult by the significant risk of re-detachment
(11-33%)2. Reported rates of IOP normalization after silicone
oil removal varies widely. In one study, SOR resulted in control of IOP in 93.4%
of patients, whereas another study reported persistence in all eyes even after
silicone oil removal7,8. Some researchers attribute the persistent IOP
rise after silicone oil removal to inflammation of the trabecular meshwork, and
its obstruction by silicone oil droplets4. Other studies compared results of SOR with
incisional glaucoma surgery versus either one done alone yielding variable
results2,9,10.

Incisional
glaucoma surgery and shunt implants may be considered in patients with unresponsive
glaucoma, especially in eyes where the angle is synechially closed. However, trabeculectomy
can be technically difficult due to subconjunctival fibrosis from prior retinal
surgery, and carry high risk of complications and failure. As an alternative, inferiorly
placed glaucoma valve implant can be used with success rate of  86% at 6 months and 76% at one year after
implantation5