Laser Iridotomy Ineffective in Pigment Dispersion Syndrome After All
March 25, 2011
Ophthalmology: For many years, the conventional wisdom- which made a lot of sense- was that pigment dispersion syndrome is due to posterior bowing of the iris against the zonules, and therefore an iridotomy would halt further pigment dispersion by equalizing the pressure gradient and making the iris more flat. A recent study, however, noted no decrease in progression to glaucoma among those who got the laser compared to those who didn’t. Oh well.
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2 Responses to “Laser Iridotomy Ineffective in Pigment Dispersion Syndrome After All”
well said. thanks for your input.
Part of the trouble with iridotomy for pigmentary glaucoma is the unpredictable nature of how any given eye reacts to the pigment that has been dispersed over the years of pigment dispersion syndrome. The vast majority of patient with just pigment dispersion syndrome but no glaucoma damage, never convert to glaucoma. If a given person’s body reacts to the pigment by the macrophage reaction damaging the trabecular meshwork while trying to clear the pigment, then the patient ends up with glaucoma. If the pigment does not induce that much of a reaction from the host, the patient never gets glaucoma.
If a patient already has pigmentary glaucoma, yes, the iridotomy will flatten the iris most of the time by stopping the reverse pupillary block. However, if there is already permanent damage to the trabecular meshwork, then it is too late.
The bottom line is that the patients who would benefit the most from iridotomy would be those who are shedding pigment but have yet to have any damage to the trabecular meshwork. However, since the vast majority of those with pigment dispersion never develop glaucoma anyway, it does not make sense to treat everyone with pigment dispersion to prevent the minority from developing glaucoma.
Until we know which patients with pigment dispersion are more likely to develop glaucoma, perhaps by some cellular marker, it does not make sense to treat every dispersion patient with an iridotomy. Furthermore, for those who have already converted to pigmentary glaucoma, an iridotomy is probably too late to make a difference.
