Symptoms of Small Fiber Neuropathy in Patients With Dry Eye Disease.

PURPOSE: Small fiber neuropathy (SFN) is a neurologic condition affecting small-diameter nerve fibers, including those innervating the ocular surface. In this study, we aim to assess the prevalence and characteristics of SFN symptoms in patients with dry eye disease (DED).

METHODS

This was a prospective study conducted at 2 academic eye centers. DED symptoms were assessed using the Ocular Surface Disease Index (OSDI) questionnaire, and adult patients with an OSDI score ≥13 and a clinical diagnosis of DED at Mass Eye and Ear and Beth Israel Deaconess Medical Center were included in the study. Ocular pain was assessed using the Ocular Pain Assessment Survey (OPAS). SFN symptoms were measured using validated Small-Fiber Symptom Survey (SSS) questionnaire, with scores ≥32.5 considered abnormal. DED signs including corneal fluorescein staining (CFS), tear breakup time (TBUT), tear production, and corneal sensitivity were assessed. Patients received standard DED treatments, and their responses were reassessed after 6 to 12 months.

RESULTS

Among 31 participants with DED (23-87 years, 80.6% female), 38.7% had abnormal SSS scores. SSS scores correlated with DED symptoms (r = 0.43 P = 0.017) and ocular pain (r = 0.62 P = 0.0003); correlated negatively with CFS (r = -0.42 P = 0.018); and did not correlate with TBUT, tear production, or corneal sensitivity. Despite standard treatments and stable clinical signs, most patients with severe SFN symptoms reported worsening dry eye symptoms in follow-up.

CONCLUSIONS

This study demonstrates that SFN symptoms were prevalent in DED population and positively correlated with ocular pain and dry eye symptoms and negatively with CFS. Patients with severe SFN symptoms reported less favorable responses to standard dry eye treatments.