Summary for the Clinician

››Pigment released into the anterior chamber causes decreased outflow facility.

››The amount of pigment observed at the slit lamp does not correlate to the risk of converting to PDG.

››PDG patients show an increased risk of rhegamatogenous retinal detachment.

››PDG patients have higher IOP peaks and greater IOP fluctuation than POAG patients.

››PDS patients have a 10% risk of converting to PDG at 5 years and 15% risk at 15 years.

from ocular hypertension to glaucoma. The former excluded patients with PDS from its analysis, while the EGPS found it to be a good predictor of glaucoma onset among patients with ocular hypertension.

45.2  Is PDG Managed Differently than Primary Open Angle Glaucoma?

45.2.1  Medical Treatment

Initial treatment involves IOP reduction using topical IOP-lowering medications. Most medication classes can be used in PDG patients and an IOP reduction similar to that seen in POAG patients is expected. Care should be taken while using cholinergic agents in these patients because of their increased risk of retinal detachment (see Sect. 45.1).

45.2.2  Trabeculoplasty

Argon laser trabeculoplasty (ALT) has been shown to be an effective procedure with higher success rates in PDG patients than in other types of open angle glaucoma. Ritch and colleagues found a cumulative success rate of 80% at 1 year, 62% at 2 years, and projected 45% at 3 years [11]. Since the increased pigmentation of the trabecular meshwork allows greater absorption of energy, it is advisable to use lower energy settings during the procedure in order to avoid trabecular damage, peripheral anterior synechiae, and subsequent permanent IOP elevation.

45.2.3  Trabeculectomy

If the target IOP range is not reached despite maximally tolerated medical therapy, trabeculectomy with or without adjunctive use of antifibrotic agents may be indicated. PDG patients require filtration procedures slightly more frequently than do patients with POAG.

The Trabeculectomy Study Group (TSG) found that PDG is one predictor of treatment success; 77% of eyes in this study showed an unqualified IOP between 6 and 16 mmHg with 1 year of follow-up [12]. The National Survey of Trabeculectomy also found good success rates with PDG [13]. However, the Advanced Glaucoma Intervention Study (AGIS) found no association between the type of glaucoma and the success rate of trabeculectomy, even though younger age was found to be a significant predictor of failure. Young patients show more intense conjunctival scarring than do older patients, which increases the chances of bleb failure.

Table 45.1  Clinical and surgical differences between primary open angle glaucoma (POAG) and pigmentary glaucoma (PG)