Retinal and optic nerve degeneration in α-mannosidosis

Orphanet J Rare Dis. 2018 Jun 1;13(1):88. doi: 10.1186/s13023-018-0829-z.

PMID: 29859105

Juliane Matlach, Thea Zindel, Yasmina Amraoui

Highlights: Optical coherence tomography (OCT) technology helps detecting early outer retinal thinning which can progress with age and potentially leads to vision loss over time.

Abstract

Background: A lack of α-mannosidase activity results in the rare, autosomal-recessive condition known as α-mannosidosis. Usual symptoms include intellectual, motor and hearing impairment, facial coarsening, and musculoskeletal problems. Ocular pathologies identified before were predominantly opacities of the cornea and lens, strabismus, and ocular motility problems. However, descriptions of retinal and optic nerve degeneration are scarce.

Methods: This study provides the ocular results of 32 α-mannosidosis patients. Spectral-Domain optical coherence tomography (SD-OCT) imaging, posterior segment evaluation, fundus photography, and retinal abnormalities were the key areas of focus.

Results: Three patients (9.4%) had tapeto-retinal degeneration with bone spicule forms in the peripheral retina or macular alterations; two of these had optic nerve atrophy. Eight retinal images could be obtained by OCT or fundus photography; of these, six revealed thinning of the outer retinal layers on OCT. Six patients (18.8%) had overall optic nerve degeneration, four of whom had partial atrophy. Two patients exhibited partial optic nerve atrophy with no retinal abnormalities on funduscopy. Cataract was seen in two (6.3%), corneal haze also in two patients (6.3%). Four (12.5%) patients experienced nystagmus, five (15.6%) patients had impaired smooth pursuit eye movements, and six patients (18.8%) had manifest strabismus.

Conclusion: Ocular pathologies are not only confined to opacities of the cornea and lens or strabismus and ocular motility disorders but tapeto-retinal degeneration and optic nerve atrophy may be a prevalent feature in α-mannosidosis. OCT technology aids in the early detection of outer retinal thinning, which can develop with aging and eventually result in vision loss.

Keywords: OCT, Ocular findings, Optic nerve atrophy, Retinal degeneration, α-mannosidosis