Histological observation of trabecular meshwork in a patient with Axenfeld-Rieger syndrome-a new theory for the mechanism of ectropion uvea in congenital glaucoma

The morphology of angle dysgenesis assessed by ultrasound biomicroscopy and its relationship with glaucoma severity and mutant genes in Axenfeld-Rieger syndrome

Background

Axenfeld-Rieger syndrome (ARS), a developmental disorder, involves anterior segment abnormalities and can lead to glaucoma. However, limited research has addressed the ultrasound biomicroscopy (UBM) characteristics of ARS. This study aimed to assess the anterior chamber angle features using UBM in ARS and determine their correlation with glaucoma severity and mutant genes.

Methods

UBM examination was conducted for 42 patients diagnosed with ARS and glaucoma. The morphology of the anterior chamber angle was classified into 6 types (type A, pure high iris insertion; type B, posterior embryotoxon; type C, iris process; type D, trabecular-iris synechia; type E, peripheral iridocorneal adhesion; type F, goniodysgenesis). Candidate genes were sequenced with next-generation sequencing. Correlations of clinical characteristics with angle dysgenesis types and mutant genes were analyzed.

Results

Among the 42 patients recruited, 6 eyes were excluded for poor quality UBM images or lack of glaucoma development. The remaining 78 eyes were categorized into 6 groups according to their dominant type of anterior chamber angle (>2 quadrants). There were statistically significant differences in onset age of glaucoma (P<0.001), untreated intraocular pressure (IOP) (P=0.016), vertical cup to disc ratio (P=0.001), and age at surgery (P<0.001) among the groups. Eyes in the type C and D groups developed glaucoma and underwent surgery at an earlier age, while eyes in the type B, E, and F groups developed glaucoma at a relatively later age. Eyes in type A group developed glaucoma and underwent surgery at the latest age, and had the lowest untreated IOP compared to the other groups. Patients with FOXC1 defects were more likely to have angle type B, type C, and type D (accounting for 93.8% of the total), whereas patients with PITX2 defects were more likely to have angle type A, type E, and type F (accounting for 92.1% of the total).

Conclusions

UBM is powerful for evaluating the anterior segment abnormalities in ARS. Combined with genetic testing results, the morphological classification helps to assess the severity of glaucoma.

Characteristics and Outcomes of Glaucoma Associated With Congenital Ectropion Uvea

PURPOSE

To determine the visual outcomes and effectiveness of glaucoma surgeries in congenital ectropion uvea.

DESIGN

Retrospective interventional case series.

METHODS

Surgeries and examination findings were collected on 11 eyes of 8 patients with congenital ectropion uvea at 2 academic sites from 2001 to 2021. Visual outcomes, surgical success (intraocular pressure [IOP]: 5-20 mm Hg, no additional IOP-lowering surgery, no visually devastating complications), and survival rates of glaucoma surgeries were assessed.

RESULTS

Glaucoma in bilateral congenital ectropion uvea was diagnosed at an earlier age (0.02 ± 0.01 years) than unilateral disease (8.9 ± 5.3 years, P = .002). All eyes required glaucoma surgery with 91% requiring multiple surgeries (3.5 ± 2.1, median 3 surgeries per eye). Trabeculotomy (8 eyes) showed 13% success rate. Although none of the 4 eyes that underwent trabeculectomy with mitomycin C needed repeat trabeculectomy, glaucoma drainage device placement, or cycloablation, 75% required bleb revision surgery. Glaucoma drainage devices (7 eyes) had a 57% success rate with 3 eyes requiring subsequent cycloablation (2) or trabeculectomy (1). At the final follow-up (8.5 ± 6.6 years, median: 7.9 years), all eyes achieved IOP control, and IOP was lower compared with presentation (13.2 ± 2.6 mm Hg vs 32.9 ± 9.9 mm Hg, P = .002). Best-corrected logarithm of the minimum angle of resolution visual acuity at the final follow-up was 0.2 ± 0.2.

CONCLUSIONS

Bilateral congenital ectropion uvea presents with glaucoma earlier than unilateral cases. The majority of eyes required multiple glaucoma surgeries. Angle surgery was less effective than trabeculectomy or glaucoma drainage devices. IOP control was obtained in all eyes and affected individuals had good visual outcomes.