Phacoantigenic Glaucoma involves granulomatous inflammation resulting from sensitization to lens proteins post cataract surgery or trauma. This short lecture covers the basics of phacoantigenic glaucoma.
Speaker: Dr. Malik Y. Kahook, Professor of Ophthalmology, University of Colorado, USA
Dr. Kahook: Lens induced glaucoma can be subdivided into distinct categories that include: 1. Phacolytic Glaucoma, 2. Lens Particle Glaucoma and 3. Phacoantigenic Glaucoma. I will cover Phacoagntigenic Glaucoma in this session of 1 Slide in 5 Minutes.
Phacoantigenic Glaucoma is a granulomatous inflammation resulting from sensitization to lens proteins post cataract surgery or trauma. The previously used descriptor was “phacoanaphylaxis”, however this term is no longer used since the disease process is not an allergic response. Occurrence is now uncommon (less than 1% of cataract surgeries) after introduction of modern phacoemulsification techniques which enhanced removal of most or all lens material at the time of cataract surgery. The immune response usually occurs within two weeks of surgery/trauma and involves an immune complex reaction mediated by IgG and the complement system. The following 2 criteria must be satisfied before definitively accepting a diagnosis of phacoantigenic glaucoma:
1. Polymorphonuclear (PMN) leukocytes must be present in the aqueous or vitreous specimen
2. The circulating lens protein or particle content of the aqueous humor must be insufficient by itself to explain the glaucoma. In other words, the volume of lens material and debris are not sufficient to cause obstruction of the aqueous outflow system.
Sending aqueous taps for analysis to identify PMNs is not common and the diagnosis is often not definitively made prior to interventions being instituted.
Mild to severe conjunctival hyperemia is usually present coupled with a decrease in visual acuity compared to early post-operative values. Slit lamp exam reveals keratic precipitates (KP) with low grade inflammation +/- vitritis and often with anterior/posterior synechiae. Gonioscopy may reveal lens material in angle, however the lens material may reside posterior to the iris and in the sulcus making ultrasound biomicroscopy helpful in the workup process. IOP may be initially lower due to inflammation inducing decreased aqueous humor production, but this is often followed with elevation in IOP and accompanying corneal edema.
Fortunately, glaucomatous optic neuropathy is not a common feature with proper identification and addressing the retained lens material often leads to resolution of the pathology. There is some evidence that this disease process is more common when lens material is intermixed with vitreous allowing for slow release of lens proteins over time.
Careful history and slit lamp examination will help direct the diagnosis and this is especially the case when recent cataract surgery has been performed and retained lens fragments are identified. Lens-Particle glaucoma, which involves direct obstruction of the outflow material with retained lens fragments, is marked by a larger volume of lens material and the lack of PMNs in the aqueous humor and will be covered in a subsequent lecture. Neovascular glaucoma, uveitic glaucoma and phacolytic glaucoma may in part mimic the disease process of phacoantigenic glaucoma but as stated, each can be ruled out with proper history and examination.
Phacoantigenic glaucoma is treated with topical therapy to lower IOP as well as steroids to control inflammation. While it is possible for the disease process to resolve with topical therapy alone, removal of the lens protein, when significant, will both speed up recovery as well as result in definitive treatment. Miotics, like pilocarpine, should be avoided as they might increase inflammation and formation of synechiae. Cycloplegics, like atropine, can be used to assist in enhancing ocular comfort, breaking posterior synechiae and/or to avoid formation of new synechiae while other treatments are initiated to control pressure and inflammation.
The surgical treatment involves anterior chamber washout with removal of any bulk lens material once it is localized in the anterior chamber. A pars plana approach is needed for material in the anterior or posterior vitreous and a partial vitrectomy is often done to remove any microscopic lens material that surrounds larger particles. Every patient should undergo dilated fundus examination with optic nerve assessment at baseline. Visual field testing can set a baseline for presence or absence of optic neuropathy and extended follow up, when possible, should be instituted to ensure recovery and addressing any future needs of the patient.
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July 14, 2021