Anterior Chamber Angles in Different Types of Mucopolysaccharidoses

Abstract Purpose To evaluate the anterior chamber angle status and estimate the intraocular pressure (IOP) in patients with mucopolysaccharidoses (MPS) type I, II, IV, and VI. Design Prospective cross-sectional study Methods This study enrolled 27 consecutive MPS patients (8 patients with MPS I, 4 patients with MPS II, 9 patients with MPS IV, and 6 patients with MPS VI) and 20 normal controls. Anterior chamber angle status was evaluated by swept-source optical coherence tomography, and intraocular pressure (IOP) was estimated by the new-generation tonometer Corvis ST. Results 12 eyes (6 patients) out of the 15 eyes (8 patients) with MPS I had very narrow angles or peripheral iridocorneal touches together with elevated IOP (80%). 6 eyes (3 patients) out of the 8 eyes (4 patients) with MPS II had plateau iris configuration, but all the 8 eyes had normal IOP. All the 18 eyes (9 patients) with MPS IV had normal angle structures, but 8 eyes (4 patients) had elevated IOP (44.4%). 9 eyes (5 patients) out of the 11 eyes (6 patients) with MPS VI had shallow but not closed angles (81.8%). Among these 9 eyes, 5 eyes had elevated IOP, and 4 out of these 5 eyes had IOP above 30 mmHg. The trabecular iris angles of MPS type I, II, VI were smaller than those of MPS type IV and control group. The angle recess areas of MPS type I and VI were smaller than those of MPS type IV and control group. Conclusions MPS type I patients are prone to have glaucoma with narrow or closed angle; MPS type II patients tend to have plateau iris; MPS type IV patients are vulnerable to open-angle glaucoma; MPS type VI patients have narrow angles not as close as those of MPS type I. MPS type I, IV, and VI had higher IOP estimates than the control group, but only MPS I and IV had higher corrected IOP estimates than the control group. The ordinary IOP estimates in MPS VI patients may be falsely high due to clouded corneas and increased corneal rigidity. The swept-source optical coherence tomography helps ophthalmologist to investigate the angle structure and the pathophysiology of glaucoma caused by MPS.