When glaucoma is refractory to medical therapy, laser therapy and surgical treatment are the options to consider. Dr. Seah is a Singapore Eye Specialist who has performed numerous glaucoma procedures including the complicated glaucoma drainage implant surgeries. With rich clinical experience in the treatment of glaucoma, he will be able to determine the best suited treatment for your condition.
Glaucoma eye drops are the most common treatments for glaucoma. These eye drops aim to either reduce the production of fluid in the eyes, or improve its outward flow, thereby reducing the pressure accumulation in the eyes.
These eye drops work by relaxing the eye muscles to increase the drainage of fluid from the eye, thereby reducing the eye pressure. They have the best user compliance because they are required only once daily.
Beta blockers were at one time the drugs of first choice in treating glaucoma. These drugs work by decreasing production of fluid in the eye.
Alpha agonists work to both decrease rate of production of fluid in the eye, as well as increase it's outflow, thus effectively reducing the eye pressure.
Similar to Beta blockers, Carbonic anhydrase inhibitors generally decrease the fluid production in the eye. These drugs are available in both eye drops and pills form. They are usually used in combination with other anti-glaucoma eye drops.
Parasympathomimetics are frequently used to control the eye pressure in narrow-angle glaucoma by increasing the outflow of fluid in the eye. These eye drops cause the pupil to constrict, which assists in opening the narrowed or blocked angle where drainage occurs.
These eye drops combine two different anti-glaucoma medicines in the same bottle. This provide an alternative for patients who need more than one type of medication.It is important to follow the recommended prescription to effectively manage glaucoma. Medical therapy requires a lifetime of compliance.
Argon Laser Trabeculoplasty (ALT) is generally recommended for patients with open-angle
glaucoma. In open-angle glaucoma, the normal drainage site of the eye (trabecular meshwork)
does not function normally. When the drainage of fluid is impeded, the eye pressure
increases and this can lead to loss of vision. ALT aims to facilitate drainage of fluid and
thereby lower the eye pressure.
An Argon laser beam is directed at the trabecular meshwork to enable the eye to drain fluid
more effectively.
SLT is an advanced treatment option that uses lower-energy laser beam than ALT. It is termed
"selective" because it leaves portions of the trabecular meshwork intact. For this reason,
it is believed that SLT produces lesser scar tissue.
Similar to ALT, a laser beam is applied to the drainage site in the eye. This results in an
increase in fluid drainage, thereby results in lowering of the eye pressure.
Transscleral cyclophotocoagulation is usually the end-stage laser treatment for cases of
advanced glaucoma in which medical therapy is insufficient to control the the eye pressure,
and are refractory to conventional laser or surgery.
During TCP, a laser beam is applied to the part of the eye which produces the fluid which
fills the eyeball (ciliary body). This process destroys the ciliary body, and thereby
effective in decreasing the fluid production, which in turn lower the eye pressure.
Study conducted by Dr Seah to evaluate the effectiveness of transscleral
cyclophotocoagulation concluded that transscleral cyclophotocoagulation is an effective
modality of therapy for refractory and end stage glaucoma.
Laser peripheral iridotomy (LPI) is generally recommended for patients suffering from, or at
risk of angle-closure glaucoma. LPI prevents patients with narrow angle from developing
acute angle closure glaucoma, which they are at higher risk of developing. For patients who
already been diagnosed with acute angle closure glaucoma, LPI helps to lower the eye
pressure as well as to prevent another attack of angle closure glaucoma.
During LPI, laser beam is aimed and multiple laser “shots” are placed into the iris to make
a small opening in the iris. This allows the fluid to bypass its normal route and "opens"
the angle.
The entire procedure takes approximately 10 minutes for each eye.
Study co-conducted by Dr Seah to evaluate the changes in the configuration of the drainage
angle in the first year after Acute Primary Angle Closure (APAC) found that in Asian eyes
with APAC, the angle did not change over 1 year, and remained stable throughout. The results
indicate the effectiveness of LPI in preventing progressive closure of the angle in the
first year after APAC.
When medications or laser therapy fail to control the eye pressure in glaucoma patients, surgical intervention is naturally the next step in the management of glaucoma.
Trabeculectomy with Anti-Metabolites has always been considered the “gold standard”
for surgical management of glaucoma. It is generally recommended for patients with
glaucoma that is refractory to medications and/or laser treatments.
In this procedure, a tiny drainage hole is made in the sclera (the white part of the
eye). Instead of draining into the normal drainage site of the eye (the trabecular
meshwork), a new drainage site is created to allow fluid to flow out of the eye into
a filtering area called a bleb. The bleb is completely covered by the transparent
outer covering (the conjunctiva) of the eye and hidden under the upper eyelid. The
procedure is done under local anesthesia and is a day surgery.
Trabeculectomy will lower the eye pressure, preventing further vision loss from glaucoma. It
is important for patient to remember that the surgery only helps to slow down or halt the
progression of optic nerve damage but does not improve the vision.
One of the reasons for trabeculectomy surgery to fail is that scarring can occur at the
drainage site after surgery and therefore close up the bleb created. In Steve Seah Eye
Center, antimetabolites, or medications that prevent scarring such as mitomycin C (MMC), is
used almost routinely during operation to enhance the success of trabeculectomy. Utility of
antimetabolite has improved trabeculectomy results and results in better control of the eye
pressure. This is also backed by research studies which have shown that with application of
MMC, the surgery was more successful than no antimetabolite at lowering IOP and reducing
postsurgical glaucoma medications. [Cohen JS, et al; Carlson DW, et al] They should,
however, be used with special care because of the serious nature of potential complications.
This is related to the concentration and duration of exposure of the antimetabolite.
Complications are rare if used by a Singapore ophthalmologist who specializes in the use of
these potent medications and the special needs for this procedure.
We are glad to say that lower eye pressure and good visual outcome have been consistently
reported in our clinic with trabeculectomy.
Cataract and glaucoma are the two most common eye pathologies in older age individuals, and these two diseases often occur simultaneously in the same eye. In Steve Seah Eye Center, it is a common practice to combine both phacoemulsification (cataract extraction surgey) and trabeculectomy in a single operation for patients with coexisting cataract and glaucoma.
Advantages of a combined surgery include:
Study co-conducted by Dr Seah found that cataract surgery after trabeculectomy increases the
risk of trabeculectomy failure, and this risk is increased if the time between
trabeculectomy and cataract surgery is shorter.
The visual acuity outcomes of combined surgery are generally excellent in our clinic.
For patients who are not a suitable candidate for trabeculectomy due to high risk of
scarring, or whom had a previous failed trabeculectomy, a glaucoma drainage implant will be
provided as a surgical alternative.
A glaucoma drainage implant, also known as a shunt tube, is a flexible device implanted in
the eye to provide an alternative passageway for fluid to drain more efficiently from inside
the eye to an external reservoir. It is like getting “new plumbing” for the eye. With a
better drainage system, this helps to control the eye pressure for patients with glaucoma.
The glaucoma drainage implant is made of a silicone tube and plate. In this procedure, the
tube is carefully inserted into the front chamber of the eye, right in front of the iris
(the coloured part of the eye). The fluid from the eye flows through the tube to the back
end of the implant (the plate) which sits on the sclera (the white wall of the eye). The
fluid will then be collected and reabsorbed. This fluid collection may be visible as a
slight bump over the plate, which is hidden by the upper eyelid.
Glaucoma drainage implants come in various shapes and sizes. Below are some of the implants
used in our clinc:
The Baerveldt Implant is a larger drainage device than other implants. Larger
implant surface is often associated with increase success of the surgery. The
end plate of the Baerveldt Implant is made of barium impregnated, rounded
silicone with surface areas of 250- or 350-mm2. Studies comparing Baerveldt
implant with implant of another brand have found that the Baerveldt implant
generally provides a longer lasting pressure lowering effect.
Study conducted by Dr Seah concluded that in Asian eyes with complicated
glaucoma, Baerveldt glaucoma implants achieve stable and satisfactory IOP
reduction with low incidence of complications in the intermediate term after
surgery.
The Express Glaucoma Shunt is a minature, stainless steel shunt. It was
engineered to exacting specifications that make it an efficient and effective
alternative for standardizing aqueous humor flow and regulating IOP during and
after implantation. The surgical time required is relatively shorter; the device
can be implanted in less than five minutes. The Express Glaucoma Shunt is proven
to be MRI safe.
Deep Sclerotomy
Deep Sclerotomy is a non-penetrating surgical procedure that is often used to
treat open-angle glaucoma. It is a relatively safe surgical procedure which
involves a minally invasive incision in the sclera (white part of the eye).
In this procedure, a small portion of the sclera is removed to create a drainage
space, thus relieving the eye pressure.
One of the drawback of traditional trabeculectomy surgery is the risks of
postoperative complications. Since sclerotomy is non-penetrating, it greatly
reduces the incidence of these complications.
