Retinal arterial but not venous tortuosity correlates with facioscapulohumeral muscular dystrophy severity

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal-dominant disease beginning with facial and shoulder girdle weakness with variable progression. Exudative retinal detachment, retinal vessel irregularities on fluorescein angiography, and retinal vessel tortuosity have been found in association with FSHD.

In this retrospective study, muscle affectedness severity was rated as mild, moderate, or severe by a neurologist masked to the retinal images. Three ophthalmologists masked to disease severity graded the degree of arterial and venous tortuosity on a scale of 1 to 4. An automated method estimated an index of tortuosity for arteries and veins from color fundus photographs. Spearman rank correlation coefficients were used to describe the relationship between retinal vessel tortuosity and disease severity.

Seven patients with an average age of 13 years (range, 7-36 years) were selected. Correlation between the subjective tortuosity for arteries, and the severity of FSHD was 0.78 (p = 0.039). The correlation coefficient for venous tortuosity was -0.06 and was not significant (p = 0.882). The correlation coefficient between the average algorithmic computer-generated tortuosity indices for arteries and FSHD severity was high (0.85, p = 0.016), but for veins it was low and not significant (0.19, p = 0.662).

The authors of previous reports have shown retinal vascular abnormalities did not correlate to FSHD disease severity. Our results suggest a correlation between the tortuosity of arteries and the severity of disease in FSHD patients. These results suggest the tortuosity of arteries can serve as a biomarker of severity of disease in these FSHD patients, either as determined by human experts or by an automated method.