A case of Chandler's syndrome revealed by ultrastructural studies of the trabecular meshwork

Authors


Maiko Awai MD
Department of Ophthalmology and Visual Science
Kumamoto University
Graduate School of Medical Sciences
1-1-1, Honjo
Kumamoto 860-8556
Japan
Tel: + 81 96 373 5247
Fax: + 81 96 373 5249
Email: maikoa-75@k7.dion.ne.jp

Abstract.

Purpose: To investigate ultrastructural changes in the aqueous outflow route and discuss the mechanisms associated with intraocular pressure (IOP) elevation in a patient with presumably early stage Chandler's syndrome.

Methods: A 47-year-old man underwent trabeculectomy because of elevated IOP. A specimen obtained during surgery was studied by transmission electron microscopy.

Results: Electron microscopy showed the presence of a monolayer composed of corneal endothelium-like cells and thick basement membrane-like material. Neovascularization was also observed in the corneoscleral trabeculum.

Conclusions: Our results indicate that several mechanisms, including the formation of basement membrane-like tissue, infiltration of inflammatory cells and neovascularization, might contribute to the elevation of IOP in Chandler's syndrome. These may occur even when there is no history of conspicuous inflammatory reaction in the anterior ocular segments.

Introduction

Iridocorneal endothelial (ICE) syndrome, including essential iris atrophy, Cogan–Reese syndrome and Chandler's syndrome, exhibits a proliferation of corneal endothelium-like cells over the surface of the trabecular meshwork and formation of peripheral anterior synechia. (Campbell et al. 1978; Yanoff 1979) We report here a case of possible early stage Chandler's syndrome documented by ultrastructural studies on a surgically obtained specimen.

Case Report

A 47-year-old man visited NTT West Kyushu General Hospital in June 1995 because of blurred vision in his left eye. Visual acuity was 20/12.5 in both eyes. Intraocular pressure (IOP) was 15 mmHg in the right eye and 21 mmHg in the left eye. Slit-lamp examination revealed an irregular corneal endothelium in the left eye. Specular microscopy revealed abnormal variations in the shape and size of corneal endothelial cells in the same eye. No obvious abnormality was found in the anterior chamber and iris. Gonioscopy showed normal and open angles in both eyes. The optic disc demonstrated glaucomatous changes in the left eye, and visual field testing showed glaucomatous defects. Intraocular pressure was controlled on timolol for 1 year. However, the IOP gradually increased up to 27 mmHg and corneal oedema developed despite three additional antiglaucoma medications. The glaucomatous changes in the optic disc and visual field defects progressed, and trabeculectomy with the use of mitomycin C was performed in January 2001.

A surgically obtained specimen of the trabecular meshwork was processed for light and transmission electron microscopy. Light microscopic examinations showed a normal looking Schlemm's canal. However, numerous large, round cells were observed between the trabecular sheets, and a layer of homogenous basement membrane-like material was found in the corneal and Schlemm's canal endothelium and trabecular cells of the angle. The latter material was positive for thrombomodulin immunoreactivities, indicating a corneal endothelium origin (Fig. 1).

Figure 1.

Light microscopic findings. (A) Note the abnormal extension of corneal endothelial cells and thick basement membrane-like material (arrows). Numerous round cells were found in the trabeculum (arrowheads). (B) Immunostaining with thrombomodulin. The homogenous basement membrane-like material was positive (arrowheads).

Electron microscopic findings revealed corneal endothelial cells and a thick basement membrane-like material on the side of the anterior chamber. Macrophages were observed in the trabeculum. Neovascularization was observed in the trabeculum between the corneoscleral and uveoscleral meshworks (Fig. 2).

Figure 2.

Electron microscopic findings. (A) A monolayer composed of corneal endothelial cells (arrowheads). Thick basement membrane-like material is seen at the side of the anterior chamber (*). Scale bar: 5 µm. (B) Neovascularization was observed in the trabeculum from the corneoscleral meshwork to the uveoscleral meshwork (*). Scale bar: 2 µm. (C) Macrophages between the cribriform meshwork (*). Scale bar: 2 µm.

Discussion

In this case, slit-lamp examination and specular microscopic examination revealed irregularity and damage of the corneal endothelium. Although slit-lamp examination showed no apparent changes in the iris and angle, histological examination revealed that thrombomodulin-like immunoreactivities were positive in the corneal and Schlemm's canal endothelium and trabecular cells of the angle. Therefore, we diagnosed this case as an early stage of Chandler's syndrome.

These results suggest that several mechanisms can explain the IOP elevation in Chandler's syndrome:

  • 1formation of a basement membrane-like tissue;
  • 2infiltration of inflammatory cells, and
  • 3neovascularization, even if inflammatory reaction in the anterior ocular segments cannot be confirmed.

Interestingly, infiltration of macrophages and neovascularization was detected in the trabeculum in addition to the basement membrane-like tissue. The coexistence of macrophages and new vessels in the trabecular meshwork of patients with sarcoidosis has been reported, along with the suggestion that this neovascularization in the trabecular meshwork may be induced by macrophages (Hamanaka et al. 2002), and may be associated with chronic infections (Tsai et al. 1990; Alvarado et al. 1994).

Ancillary