Ultrasound Biomicroscopy in Asymmetric Pigment Dispersion Syndrome and Pigmentary Glaucoma

Abstract

To identify differences in anterior chamber anatomy among patients with asymmetric pigment dispersion syndrome and no other discernible cause for the asymmetry. Methods: Ultrasound biomicroscopy and A-scan biometry were performed on both eyes of 13 patients with asymmetric pigment dispersion syndrome without a known cause for asymmetric involvement. A radial perpendicular image in the horizontal temporal meridian detailing the scleral spur, angle anatomy, and iris configuration was obtained for each eye by 2 examiners. Results: There were no differences in lens thickness (P=.33), refractive error (P=.84), or axial length (P=.99) between more and less affected eyes. However, the mean ± SD iris concavity (PϽ.001), iris-lens contact distance (P=.02), and distance from the scleral spur to the iris insertion (0.42 ± 0.11 vs 0.29 ± 0.06 mm) (P = .002) were greater in the more affected eye of each patient. Conclusion: A more posterior iris insertion predisposes to the phenotypic expression of pigment dispersion syndrome.

Anterior-segment morphology and corneal biomechanical characteristics in pigmentary glaucoma

“…In PG, for example, it has been demonstrated that the insertion of the iris into the ciliary body is more posterior 3. This has been suggested to increase the irido-zonular contact and induce a more significant clinical picture 3. Histologic studies revealed that areas of disrupted iris pigment epithelium had a radial distribution corresponding to the peripheral iris transillumination defects,4,5 supporting the concepts originally proposed by Campbell 4…”

“…Posterior bowing of the mid peripheral iris is of particular importance in the etiology of PDS, as it results in a close irido-zonular contact that can be confirmed by ultrasound biomicroscopy (UBM) and anterior-segment optical coherence tomography (AS-OCT). In PG, for example, it has been demonstrated that the insertion of the iris into the ciliary body is more posterior 3. This has been suggested to increase the irido-zonular contact and induce a more significant clinical picture 3.…”

Pigment Dispersion Syndrome and Pigmentary Glaucoma

“…Two pupillary disorders -Horner's syndrome and Adie's pupil -can result in asymmetric PDS, with the involved eye being less pigmented in Horner's syndrome and more pigmented in Adie's pupil. In patients in whom no clear cause for asymmetric PDS is found, a more posterior iris insertion and greater iridolenticular contact will be present in the eye with the greater PDS [ 5 ]. PDS may resolve partially or completely as a result of cataract extraction, lens subluxation, chronic treatment with miotic therapy, or iridotomy.…”

“…Mechanical rubbing during pupillary movement disrupts the iris pigment epithelium, releasing pigment granules into the aqueous humor. Greater iridozonular contact will cause greater pigment dispersion [ 5 ]. Trabecular endothelial cells phagocytose and remove pigment granules accumulated in the intertrabecular spaces [ 6 -8 ].…”

MTHFR C677T Homozygous Mutation in a Patient with Pigmentary Glaucoma and Central Retinal Vein Occlusion

“…A marked asymmetric involvement is unusual. Independently of PG, such a finding may occur because of some second conditions, such as at the clinical presentation of cataract formation and extraction, Horner's syndrome, Addie's pupil and Marfan's syndrome [1] .…”