For glaucoma specialists, the question of whether angle-closure glaucoma is a surgical disease is an important one, and in my opinion, the answer to this question is 'yes.' Surgical options for angle-closure glaucoma are different than those for open-angle glaucoma and depend upon such factors as the extent of IOP control with medications and the presence of coexisting cataract. Our choice of surgical intervention needs to take these factors into account.
Eyes with angle-closure glaucoma progress from potential angle closure to angle closure with or without peripheral anterior synechiae (PAS), followed by an acute or chronic rise in IOP, and finally glaucomatous optic neuropathy (Figure 1). My colleagues and I are focused on this last stage of angle-closure glaucoma, which has already induced structural and functional changes of the optic disc.
CONSULTING THE GUIDELINES
The treatment guidelines for angle-closure glaucoma
are derived through consensus by glaucoma experts
based on the best available evidence. I helped to develop
the Asia Pacific Glaucoma Guidelines.1 When we
released the second edition in 2008, the information on
angle-closure glaucoma was incomplete, particularly
regarding the surgical aspect of this disease. A more
recent publication comes from the American Academy
of Ophthalmology's Preferred Practice Patterns,2 which
was released in October 2010. These guidelines address
the goals of managing a patient with primary angle-closure
glaucoma:
• to reverse or prevent the angle-closure process
• to control IOP
• to prevent damage to the optic nerve
Iridotomy is indicated in all eyes with primary angleclosure glaucoma.
MANAGEMENT PRINCIPLES
The management of primary angle-closure glaucoma focuses on correcting the problem by modifying the angle-closure configurations, controlling IOP, and minimizing changes in the optic disc and visual field (Figure 2). Options for correcting this condition generally include laser or surgical peripheral iridotomy, iridoplasty, topical pilocarpine, and removal of the crystalline lens. Unfortunately, according to a study published by Aung and colleagues,3 nearly 60% of primary angle-closure glaucoma patients demonstrate increased IOP and damage to the optic nerve head after successful laser peripheral iridotomy upon long-term follow-up. We may opt to use additional treatments such as laser iridoplasty or goniosynechialysis to reopen the angle after a peripheral iridotomy. Goniosynechialysis may improve aqueous outflow, particularly when it is performed within 6 months after an acute attack.
IS LENS REMOVAL NECESSARY?
We know that the crystalline lens contributes significantly to the mechanism of primary angle closure, particularly in the Asian population. Do we therefore need to remove the lens?
According to one series published by Sihota and colleagues, 4 more than one-fourth (35%) of primary angleclosure glaucoma patients needed some kind of surgical intervention to control IOP at the 6-year follow-up. Although various surgical options are available, treatment for this condition is more complex than for open-angle glaucoma, because the lens is involved. We must decide whether to remove the lens with or without performing goniosynechialysis or to do a combined surgery.
The outcomes of trabeculectomy to treat angle closure seem to be less favorable than for open-angle glaucoma, with a higher risk of filtration failure. Trabeculectomy also increases the chance of further shallowing of the anterior chamber, the risk of developing malignant glaucoma, and the risk of cataract formation. Although a study by Maris et al5 showed significantly lower complication rates with the EX-PRESS Glaucoma Filtration Device (Alcon Laboratories, Inc., Fort Worth, TX) versus trabeculectomy in patients with primary open-angle glaucoma, experience with this approach in these patients is still limited and subject to potential future studies.
SUBCATEGORIZING PATIENT POPULATIONS
Deciding Between a Single or Combined Therapy
In terms of clinical approach, we can divide angle-closure
glaucoma patients by those with coexisting cataract and
those without. We can subcategorize these groups into
individuals with medically controlled versus uncontrolled
angle-closure glaucoma. Within these subcategories, we
need to consider whether to simply perform phacoemulsification
surgery or a combined phacoemulsification and
trabeculectomy procedure.
Medically Controlled Angle-Closure Glaucoma With
Cataract
A prospective, randomized trial conducted by Tham
and colleagues in Hong Kong6 evaluated 35 eyes with
medically controlled angle-closure glaucoma that underwent
phacoemulsification alone and 37 eyes that had
combined phacoemulsification and trabeculectomy surgery.
The phacoemulsification-only group experienced a
9.82% reduction of IOP, and 59.2% decreased their use of
medications.
Although the combined phacoemulsification and trabeculectomy procedure appeared to deliver slightly better results, this group also had significantly more complications. If we adjust for the seven reported cases of hypotony in the combined phacoemulsification and trabeculectomy group, the outcomes of the two groups are very similar. Thus, for patients with medically controlled angle-closure glaucoma and cataract, the benefit of combined phacoemulsification and trabeculectomy is not sufficient to justify the additional complications. For this reason, phacoemulsification alone may be indicated in such a group.
Uncontrolled Angle-Closure Glaucoma With Cataract
When considering the best procedure for medically
uncontrolled angle-closure glaucoma with cataract, we
can consult a smaller series of Tham's randomized trial.7
The study also found that combined phacoemulsification
and trabeculectomy generated a greater IOP-lowering
effect (1.97 mm Hg) than phacoemulsification alone, and
the combination therapy enabled patients to reduce their
medications. Again, however, combined phacoemulsification
and trabeculectomy was found to produce significantly
more complications, and I therefore recommend
phaco surgery alone for patients who are at higher risk for
trabeculectomy complications as well as for those who
are not willing to accept the higher risk of complications. I
would advise a combined procedure for patients with
poor compliance, drug allergy, or a lack of access to drugs.
Angle-Closure Glaucoma in Eyes Without Cataract
In considering angle-closure glaucoma in eyes without
cataracts, we can once again subdivide these patients
into those whose condition is medically controlled or
not. For medically controlled angle-closure glaucoma, I
think it is fairly easy to maintain the medication regimen,
unless the patient expresses a desire to discontinue it.
For uncontrolled angle-closure glaucoma, I feel the current
evidence is insufficient to correctly identify the lens
mechanism. Therefore, I feel a reserved approach is warranted
and that we must address this group similarly to
eyes with primary open-angle glaucoma. Remember, cataract extraction alone may yield substantial IOP reduction
in selected angle-closure cases.
CONCLUSION
I think angle-closure glaucoma is indeed a surgical disease that has treatment options distinct from those used in primary open-angle glaucoma with coexisting cataract. If the IOP is controlled with medications, we can perform phacoemulsification alone; if not, then combined phacoemulsification and trabeculectomy may be indicated. For angle-closure glaucoma patients without coexisting cataract, I advise continuing a regimen of medication as long as it can control the IOP. For uncontrolled angle-closure glaucoma without cataract, trabeculectomy may be a better option, and lens removal must be reserved for those eyes whose lens component can be correctly documented.
Prin Rojanapongpun, MD, is chairman of the Department of Ophthalmology at Chulalongkorn University, Bangkok, Thailand. He acknowledged no financial interest in the products or companies described herein. Dr. Rojanapongpun may be reached at +(66) 2-256-4421; prinoph@gmail.com.
