Retinal nerve fiber hypertrophy in ataxia of Charlevoix-Saguenay patients

Abstract

Purpose: To present full ophthalmologic examination and retinal nerve fiber layer (RNFL) photographs of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) patients showing significant increases in RNFL thickness compared to healthy subjects, but without myelinated retinal fibers.

Methods: The study design was observational case series. Ten eyes of five patients with molecular confirmation of ARSACS underwent a full ophthalmologic examination that included clinical history, visual acuity, biomicroscopy of the anterior segment, gonioscopy, Goldmann applanation tonometry, central corneal ultrasonic pachymetry, ophthalmoscopy of the posterior segment, standard automatic perimetry (Humphrey field), simultaneous stereophotographs of the optic disc after mydriasis, a series of five red-free digital fundus photographs for RNFL evaluation, topographic analysis of the optic disc using the Heidelberg retina tomography, and measurement of peripapillary RNFL thickness with Cirrus optical coherence tomography.

Results: All patients showed abnormal visual fields, normal optic discs with a mild to strikingly increased visibility of RNFL in color stereophotographs, normal Heidelberg tomography, and moderate to markedly increased RNFL thickness in Cirrus tomography (average thickness ranging from 119 μm to 220 μm).

Conclusions: We found evidence of RNFL hypertrophy in ARSACS patients that may have been interpreted as hypermyelinated retinal fibers in previous reports. A revision of ARSACS diagnostic criteria, particularly with regard to retinal alterations, is necessary.

Figure 1

Figure 1. Patient 4 ophthalmologic exploration. Representation of visual field of right and left eye (A and B, respectively), Heidelberg retinal (C and D, respectively) and optical coherence tomographic assessments for both eyes (E). The images F and G represent optic disc color stereophotographs of right and left eye, respectively. The images H and I show retinal nerve fiber layer monochromatic photographs for both eyes. Results reflect mild nonspecific defects in the visual field, normal optic nerve morphology, and an increase in global retinal nerve fiber layer thickness and density.

Figure 2

Monochromatic and stereophotographs in autosomal recessive spastic ataxia of Charlevoix-Saguenay 198 patient. A: A monochromatic photograph of retinal nerve fiber layer in patient 4 (left eye) shows increased visibility of fibers and a thin sector defect (included between arrows). B: A stereophotograph of the same eye shows the telltale yellow discoloration of the retinal nerve fiber layer streaks.

Figure 3

Comparison of an autosomal recessive spastic ataxia of Charlevoix-Saguenay patient and a healthy subject. The patient (left) shows an increase of retinal nerve fiber layer thickness in the optical coherence tomograph (A), and moderately increased visibility of the retinal nerve fiber layer in the stereophotograph (B) of the optic disc and in the monochromatic red-free digital fundus photograph (C), compared with healthy eye (D-F).