Ciliary-Block Glaucoma

Signs and Symptoms: Patients with ciliary-block glaucoma are typically hyperopic with small or nanophthalmic eyes. The condition usually develops after ocular surgery--typically glaucoma surgery, and most commonly filtration surgery, but also peripheral iridectomy or cataract extraction. There may have been a period of hypotony due to over-filtration following glaucoma surgery. At the slit lamp, there will be a shallow or non-existent anterior chamber. Also, they may have a history of beginning miotic therapy. Patients who develop significant inflammation, such as scleritis, may also develop ciliary-block glaucoma.

Patients with ciliary-block glaucoma will present with intense pain, ocular injection, a cloudy cornea with copious edema and subsequent blurred vision, a flat anterior chamber and elevated intraocular pressure. The flat anterior chamber frequently appears even with patent iridotomies or iridectomies.

Pathophysiology: Classic ciliary-block glaucoma occurs following filtering surgery, typically in an eye with a preexisting narrow angle and shallow chamber. Eyes with shallow anterior chambers undergoing surgery are at risk for the condition. One theory holds that these patients have very small uveal effusions due to ocular hypotony from over-filtration after surgery. These small effusions produce a rotation of the ciliary body with subsequent complete angle closure. Thus, according to this theory, ciliary block does not actually occur. In some cases, a retro-iris tumor can physically push the iris and lens into apposition and mimic ciliary-block glaucoma. In rare patients who are anatomically predisposed, the use of pilocarpine can precipitate ciliary-block glaucoma.

The more widely accepted theory holds that a tight apposition of ciliary processes to the lens or anterior vitreous forms either after surgery or due to a natural predisposition. This prevents the aqueous from flowing into the anterior chamber, and instead diverts it into the vitreous cavity. An abnormally impermeable anterior hyaloid face may play a role, in that the aqueous cannot diffuse from the vitreous and thus expands the volume of vitreous. This pushes the lens and iris towards the cornea with subsequent shallowing of the anterior chamber and closure of the angles.

The classic appearance is a shallow axial depth (lens-corneal distance) and a shallow peripheral depth (iris-corneal distance). In ciliary-block glaucoma, iridotomy will have no effect; the hallmark of ciliary-block glaucoma is a closed angle and shallow chamber with patent iridotomy or iridectomy.

Management: The goal of management of ciliary-block glaucoma first aims medically to break the apposition of the ciliary body and ciliary processes to the lens and anterior vitreous, relax the ciliary body and lens zonules, and allow the lens to relax posteriorly. Atropine 1% and phenylephrine 2.5% or 10% (both bid) can accomplish this. Aqueous suppressants will temporize the intraocular pressure and topical steroids will ameliorate the inflammation. Miotics are strictly contraindicated; they can precipitate this condition. You can use oral hyperosmotic agents to shrink the vitreous. Medical therapy is used initially in an attempt to manage ciliary block glaucoma.

If medical management does not succeed, there are surgical options. The first involves disruption of the anterior hyaloid face to allow aqueous to escape from the vitreous cavity. This potentially redirects the aqueous into the anterior rather than the posterior chamber. The most common method involves Nd:YAG laser photodisruption of the anterior vitreous face through an iridectomy or iridotomy hole or through the pupil. This may create an opening for aqueous to reach the anterior chamber.

Vitrectomy is a more invasive option. Here, the surgeon "debulks" the vitreous, relaxing the iris and deepening the anterior chamber. The procedure also removes pockets of aqueous within the vitreous and disrupts the anterior vitreous face; this may rectify the blockage that prevented the misdirected aqueous from ultimately getting through the pupil.

Unfortunately, after successful treatment of the ciliary-block glaucoma, the angle may remain closed due to extensive peripheral anterior synechiae. If more than half of the angle remains closed, intraocular pressure will remain permanently elevated despite successful treatment. In this case, the surgeon may try to break the peripheral anterior synechiae with a gonio-synechialysis. In an inflamed eye, filtration is likely to fail, even with the use of antimetabolites. For this reason, the surgeon will typically use a tube shunt. If synechiae closes the angle, a tube shunt is mandatory.

Clinical Pearls:

• Pupillary block is the most common condition that mimics ciliary-block glaucoma. Laser iridotomy will relieve papillary-block angle closure, but will have no effect on ciliary-block glaucoma. Laser iridotomy is necessary to differentiate these two conditions.
• Choroidal effusion with a shallow chamber, particularly after glaucoma filtration surgery, is the second most common differential diagnosis for ciliary- block glaucoma. Ophthalmoscopy will show large effusions. Small, suprachoroidal effusions can cause an anterior rotation of the ciliary body and precipitate this condition. However, these small effusions are typically only detectable with ultrasound biomicroscopy.
  

Other reports in this section

• Crystalline Lens Subluxation
• Ciliary-Block Glaucoma
• Primary Open-Angle Glaucoma
• Pigment Dispersion Syndrome and Pigmentary Glaucoma
• Pseudoexfoliation Syndrom and Pseudoexfoliative Glaucoma
• Anterior Uveitis