Ultrabiomicroscopic-histopathologic correlations in individuals with autosomal dominant congenital microcoria: three-generation family report

Abstract

Background: Congenital microcoria (CMC) is due to a maldevelopment of the dilator pupillae muscle of the iris, with a pupil diameter of less than 2 mm. It is associated with juvenile open angle glaucoma and myopia. We report on a three-generation Mexican-Mestizo family with CMC. The eldest member's iris biopsy proved muscle anomalies. Further, we analyzed novel ultrasound biomicroscopy findings in the family members who did not require surgery.

Patients and methods: A 62-year-old woman, her 41-year-old son and her 9-year-old grandson affected with microcoria since birth, documented by clinical examination and ultrasound biomicroscopy. The eldest member underwent phacoemulsification, and a biopsy of the iris and the anterior capsule of the lens was taken.

Results: Ultrasound biomicroscopy confirmed the CMC diagnosis showing iris thinning and a pupil diameter of less than 2 mm. Histopathology of the iris showed a significant reduction of smooth muscle cells, but no alterations of the anterior lens capsule.

Discussion: Although CMC is a rare disorder, which is due to a maldevelopment of the dilator pupillae muscle of the iris, it could be associated with juvenile open angle glaucoma and myopia; therefore, precise diagnosis is required. Ultrasound biomicroscopy could be a great option to confirm the disorder.

Keywords: Histopathology; Iris; Microcoria; Ultrasound biomicroscopy.

Fig. 1

Patient 1 with pupils of less than 2 mm in scotopic illumination, with a hyperpigmented peripupillary area (a right eye; b left eye). After surgery, the pupils were 5 mm in size (c right eye; d left eye).

Fig. 2

a Right eye of the 41-year-old son (patient 2). b Right eye of the 9-year-old grandson (patient 3). c 50-MHz ultrabiomicroscopy showing iris diameter of less than 1.8 mm and iris thickness of less than 830 μ.

Fig. 3

a Histological section of pupillary border showing fusiform and dendritic melanocytes, a few blood vessels, and no smooth muscle cell capsules and an underlying pigmentary epithelial layer (H&E stain). b Histological section of iris middle stroma with a few smooth muscle fibers and a thin appearance. c Masson's trichrome stain showing melanocytes in the iris anterior stroma, smooth muscle fibers, connective tissue and pigmentary epithelium. d PAS stain of the anterior lens capsule showing regular thickness base membrane and cuboidal epithelial cells underneath.