Smell Sensitivity Reduced in Pseudoexfoliation Glaucoma, Exfoliation Syndrome

Patients with exfoliation syndrome (XS) and exfoliative glaucoma (XFG) appear to have reduced smell sensitivity and identification capability compared with patients with primary open-angle glaucoma (POAG) and individuals without glaucoma, according to research published in the Journal of Glaucoma.

Between February 2018 and June 2019, researchers conducted a prospective, cross-sectional study at a single center to investigate smell sensitivity in POAG, XFG, and XFS compared with healthy controls.

They used the Sniffin’ Sticks smell test to determine patients’ smell threshold values and odor discrimination and identification and analyzed 1 eye per patient. One-way analysis of variance and post-hoc statistical tests were used to compare the differences between the groups. 

The study included 20 patients with POAG, 20 patients with XFG, and 20 patients with XFS, and 20 age- and sex-matched healthy control participants with no evidence of ocular disease. The researchers observed a significant difference in the mean age of participants across the groups (control group, 65.3±5.9 years; range 51-75; POAG group, 65.6±8.1 years; range, 47-76; XFG group, 69.5±5.8 years; range, 57-83; XFS group, 62.3±3.7 years; range, 52-66; P =.005).

The groups showed a significant difference in the smell threshold and odor discrimination and identification scores. The median smell threshold level was 4.5 (range, 0-7.5) in the POAG group, 4 (range, 0-7.5) in the XFG group, 5 (range, 4.5-6) in the XFS group, and 5.5 (range, 4-7.5) in the control group (P =.003). Post-hoc tests revealed that the POAG and XFG groups had a significantly lower smell thresholds than the control group (P =.033 and P =.001, respectively) and that the XFG group had a significantly lower threshold than the XFS group (P =.003).

The median smell discrimination and identification scores were 12 (range 2-14) and 26 (range, 4-30.5) in the POAG group, 8 (range, 0-13) and 19 (range, 0-29.5) in the XFG group, 11 (range, 10-13) and 28.3 (range, 22.8-30.5) in the XFS group, and 12 (range, 9-14) and 29 (26.5-32) in the control group. The researchers found that the median smell discrimination and identification scores were significantly different among the groups (P <.001 for both). They also demonstrated that the XFG group had a significantly lower smell discrimination and identification scores than the POAG, XFS, and control groups (ranging from P <.000 to P <.02).

The investigators report that these findings “may be important in terms of the effect of the neurodegenerative process on the pathogenesis of glaucoma.”

Reference

Dikmetas O, Aygün O, Kocabeyoglu S, et al. Smell sensitivity in primary open-angle glaucoma and pseudoexfoliation glaucoma. J Glaucoma. 2022;31(5):300-304. doi:10.1097/IJG.0000000000001999