Reduced retinal nerve fiber layer (RNFL) thickness in ALS patients: a window to disease progression

To assess RNFL thickness in ALS patients and compare it to healthy controls, and to detect possible correlations between RNFL thickness in ALS patients and disease severity and duration.

Study population consisted of ALS patients and age- and sex-matched controls. We used the revised ALS functional rating scale (ALSFRS-R) as a measure of disease severity. RNFL thickness in the four quadrants were measured with a spectral domain OCT (Topcon 3D, 2015).

We evaluated 20 ALS patients (40 eyes) and 25 healthy matched controls. Average RNFL thickness in ALS patients was significantly reduced compared to controls (102.57 ± 13.46 compared to 97.11 ± 10.76, p 0.04). There was a significant positive correlation between the functional abilities of the patients based on the ALSFRS-R and average RNFL thickness and also RNFL thickness in most quadrants. A linear regression analysis proved that this correlation was independent of age. In ALS patients, RNFL thickness in the nasal quadrant of the left eyes was significantly reduced compared to the corresponding quadrant in the right eyes even after adjustment for multiplicity (85.80 ± 23.20 compared to 96.80 ± 16.96, p = 0.008).

RNFL thickness in ALS patients is reduced compared to healthy controls. OCT probably could serve as a marker of neurodegeneration and progression of the disease in ALS patients. RNFL thickness is different among the right and left eyes of ALS patients pointing to the fact that asymmetric CNS involvement in ALS is not confined to the motor system.