Pigmentary Glaucoma Treatment & Management

Updated: Oct 23, 2018
  • Author: Jim C Wang (王崇安), MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Treatment

Approach Considerations

The intraocular pressure (IOP) in pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) is subject to large spontaneous fluctuations. This tendency should be kept in mind when considering treatment and evaluating IOP response to therapies.

Despite full PDS features (iris concavity, typical transillumination defects, angle pigmentation), patients who do not have elevated IOP or any abnormality in outflow dynamics are extremely unlikely to develop pigmentary glaucoma. Animal studies have also shown that, in normal eyes, instilling vast quantities of pigment into the anterior chamber is not sufficient to produce glaucoma. An inherent predisposition to trabecular dysfunction, unrelated to pigment release, must be present to cause pigmentary glaucoma. [4]

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Medical Care

Of the many individuals with pigment dispersion, fewer than half will develop elevated IOP or pigmentary glaucoma. However, because pigment dispersion syndrome is a risk factor for the development of ocular hypertension, all patients with this disorder should undergo periodic eye examinations. The frequency of follow-up visits may be tailored based on the severity of optic nerve damage, ocular hypertension, and degree of pigment accumulation.

Pigment dispersion syndrome is typically a bilateral disease, although asymmetry may occur. A correlation is noted between the amount of pigment lost from the posterior surface of the iris, increased degree of pigmentation in the trabecular meshwork, and degree of dysfunction in the trabecular meshwork as evidenced by elevation of the IOP. The size and density of the Krukenberg spindle does not necessarily correlate with trabecular meshwork damage. However, the amount of pigment that is presented to the trabecular meshwork does play a role in the elevation of the IOP. Markedly asymmetric disease is usually due to an additional factor, making one eye worse, such as anisometropia or the development of exfoliation syndrome or angle recession, or an additional factor acting to prevent the development of pigment dispersion syndrome, such as aphakia or Horner syndrome.

Progressive glaucomatous optic neuropathy in pigmentary glaucoma is primarily pressure-dependent, and reduction of IOP is the mainstay of therapy. In addition to monitoring of IOP, sequential ophthalmic examinations should include gonioscopy to assess the degree and progression of trabecular pigmentation, stereoscopic evaluation and photography of the optic nerve, and perimetry.

Because the degree and stage of pigment liberation, IOP, and extent of glaucomatous optic neuropathy vary among individuals, each must be evaluated to determine the proper course of intervention. As understanding of the pathogenesis of pigment liberation expands, consideration should also be given to gearing therapy toward eliminating acute pigment release, rather than just treating elevated IOP.

Initial medical therapy for pigmentary glaucoma is aqueous suppression with a topical beta-blocker, primarily because of the relatively easy dosing schedule and minimal side effects.

Prostaglandin analogues, which lower IOP by increasing uveoscleral outflow, are also effective in treating pigmentary glaucoma and offer the advantage of once daily administration. The iris surface color change that may occur during therapy appears to involve increased melanin production by iris melanocytes and is not known to affect the iris pigment epithelium (IPE) or result in pigment dispersion.

Alpha-agonists are useful in pigmentary glaucoma, but the development of allergy in as many as 50% of patients precludes the long-term use of dipivefrin, epinephrine, and apraclonidine in many individuals. Brimonidine tartrate 0.2% may provide satisfactory IOP with less allergic reaction than other drugs in this class.

Topical carbonic anhydrase inhibitors are useful agents for treating pigmentary glaucoma and are generally well tolerated. Systemic agents should be reserved for particularly difficult circumstances or when the risks of surgery are unacceptably high.

Miotic therapy

Parasympathomimetics may also be administered.

Pupillary miosis increases resistance to aqueous flow from the posterior chamber, past the lens surface, and through the pupil into the anterior chamber. This increased resistance allows aqueous pressure to build within the posterior chamber (ie, relative pupillary block) and forces the iris to move anteriorly, away from the zonules, and assume a convex configuration. The relief of iridozonular contact following miotic therapy has been demonstrated with ultrasound biomicroscopy (UBM).

However, miotics are poorly tolerated in young individuals because of the associated spasm of accommodation and blurring of vision. An extended-release pilocarpine delivery system (Ocusert) was often effective without disabling adverse effects; however, it is no longer commercially available.

A careful peripheral retinal examination should be performed before and after the institution of or change in miotic therapy because of the higher incidence of retinal breaks and detachment in these patients.

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Surgical Care

Laser iridectomy

Laser iridectomy eliminates the iris concavity in most patients with pigment dispersion syndrome by permitting equalization of pressures between the anterior and posterior chambers. This causes the iris to flatten, thereby decreasing iridozonular contact and resultant pigment dispersion. Anecdotal evidence suggests that this can prevent continued pigment liberation, result in a reversal of trabecular pigmentation, and, subsequently, lower IOP. However, long-term lowering of IOP and stabilization of glaucomatous optic neuropathy and visual field loss have not been demonstrated conclusively. Although theoretically sound, laser iridectomy should be used with caution because of the paucity of data regarding the long-term efficacy of this procedure.

Laser trabeculoplasty

Argon laser trabeculoplasty may be offered as a treatment in the management of uncontrolled pigmentary glaucoma. Although the initial result is often good, a larger proportion of patients can lose control of IOP when compared to patients with primary open-angle glaucoma (POAG), and the loss of control can occur in less time. In contrast to other forms of open-angle glaucoma, younger patients appear to respond better to trabeculoplasty than older individuals. Selective laser trabeculoplasty has been reported to result in marked and sustained IOP elevation, necessitating trabeculectomy in a few eyes with pigmentary glaucoma; therefore, it should be used with great caution. [18]

Filtering surgery

The surgical management of patients with pigmentary glaucoma follows the same principles and considerations used in the management of primary open-angle glaucoma. The appearance and change in the optic nerve along with visual field defects should be the principal guidelines used in deciding whether surgery is needed. Most patients respond well to standard filtration operations, although antifibrosis agents may be indicated to achieve a low target pressure or for reoperation. No unusual problems are typically encountered during cataract surgery.

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Long-Term Monitoring

Long-term monitoring of pigmentary glaucoma (PG) is important to assess the effectiveness of the therapy.

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