Pseudoexfoliation of lens capsule
Pseudoexfoliation of lens capsule
Description, Causes and Risk Factors:
Deposition in all parts of the eye, including the lens capsule, of a material derived from basement membranes. If this material clogs the trabecular meshwork(TM), impeding the outflow of aqueous humor from the eye, glaucoma may result.
Due to accumulation of abnormal basement membrane material at the pupillary margin, there is increased apposition with the iris and subsequent erosion of iris pigment as the pupil dilates and constricts. This leads to increased iris transillumination and deposition of pigment granules on the endothelium, iris surface and TM similar to pigment dispersion syndrome. Because this condition involves deposition of material on the anterior lens capsule and not flaking-off of the lens capsule, lensectomy is not a remedy. In fact, some have observed exfoliative material deposits on intraocular lens implants.
The development of glaucoma typically occurs due to a buildup within the TM of pigment granules and pseudoexfoliative material. Patients develop secondary open angle glaucoma. However, studies have identified patients with increased IOP but no decrease in aqueous outflow. In these cases, the glaucomatous mechanism is unknown.
Exfoliation was first noticed in the Scandinavian countries, where it was believed to have a much higher incidence than elsewhere. The prevalence of exfoliation in patients over 60 years of age is 6.3% in Norway, 4% in Germany, and 4.7% in England. The older the age group studied, the greater the incidence of exfoliation.
The condition is most common in the sixth to eighth decade, with actual glaucoma developing later in this age range. There is no racial, sexual or geographic predilection. Typically, pseudoexfoliation of lens capsule begins unilaterally, but becomes bilateral within about seven years.
Patients with pseudoexfoliation of lens capsuleremain asymptomatic until an advanced glaucoma develops.The patient presents with a fine, flaky material on the anterior lens capsule at the pupillary margin. Over time, this coalesces into a characteristic "bulls-eye" pattern seen in pseudoexfoliation. There is often increased transillumination of the iris at the pupillary margin and there may be pigment granules on the endothelium and iris surface. Within the angle, there may be observable pigment or clear flaky material. Initially, intraocular pressure (IOP) is unaffected; however, elevated IOP develops in up to 80 percent of patients.
When first diagnosing pseudoexfoliation of lens capsule, perform automated visual fields to look for pre-existing field loss since pseudoexfoliation of lens capsule undergoes periods of exacerbation and remission.
A thorough history may reveal a family history of pseudoexfoliation of lens capsule. A slit-lamp exam with IOP measurement can expose many of the findings in pseudoexfoliation of lens capsule. In addition, gonioscopy should be performed to assess for pigment deposition and a Sampaoelesi's line. The anterior chamber angle should also be examined in order to ensure safe dilation, followed by a dilated fundus exam with stereo disc photographs to identify any glaucomatous change. Visual field testing may be necessary to check for any characteristic peripheral visual field loss and to ascertain the potential stage of glaucoma.
Various imaging studies can also be used to detect and monitor glaucomatous changes in the retinal nerve fiber layer and optic disc. Optical coherence tomography (OCT) allows the retinal nerve fiber layer to be assessed for any changes. Heidelberg retina tomography II (HRT-II) is another imaging study that can provide measurements of the optic disc and retinal nerve fiber layer. Both OCT and HRT can be used to aid in the diagnosis and follow-up of patients with Pseudoexfoliation of lens capsule.
Pseudoexfoliation of lens capsule without a pressure rise requires only periodic monitoring of IOPs, discs and visual fields.
Treat pseudoexfoliation of lens capsule in the same manner as POAG (primary open-angle glaucoma). Use topical beta-blockers, topical carbonic anhydrase inhibitors, prostaglandin analogs and alpha adrenergic agonists if not systemically contraindicated. However, the IOP level in pseudoexfoliation of lens capsule is typically higher than in POAG and is more difficult to temporize. Laser trabeculoplasty and filtration surgery are often employed earlier than in POAG.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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