Fuchs Dystrophy Involves Diurnal Refractive Changes

Patients with Fuchs dystrophy may experience their worst vision upon awakening, which ultimately improves throughout the course of the day, according to a study published in Cornea. Clinicians should consider these diurnal variations when conducting clinical assessments, the report suggests.

Researchers included individuals with advanced Fuchs dystrophy (n=73; eyes, 91) and control group participants (n=26; eyes, 26) in the prospective cohort study. Participants underwent baseline near and distance visual acuity measurements during the afternoon the day and during a follow-up visit immediately upon awakening the next morning. The team also performed a diurnal variation assessment among another group of participants (Fuchs dystrophy, n=29; control individuals, n=15) by obtaining refractive measurements upon awakening and during 30-minute intervals for a 2 hour duration.

At baseline (afternoon), patients with Fuchs dystrophy had a mean best-corrected distance visual acuity of 73 Early Treatment Diabetic Retinopathy Study (ETDRS) letters compared with 79 letters among control group participants. After awakening the next day, distance visual acuity decreased by 3 letters (95% CI, −4 to −1) among patients with the endothelial corneal dystrophy. No significant differences were noted among control group participants between baseline and follow up.

Patients with Fuchs dystrophy who participated in the diurnal variation assessment experienced visual acuity improvements of 2 letters per hour (95% CI, 1-2) compared with 1 letter per hour (95% CI, 0-2) among control group participants during the 2-hour duration.

Overall, 30% of patients with the endothelial corneal dystrophy and 7% of control group participants experienced spherical equivalent changes between 0.5 and 1.0 diopter (D), and 1 patient experienced a change greater than 1.0 D compared with baseline.

“[P]atients with Fuchs dystrophy experience deterioration in near and distance visual acuity after eye opening compared with late afternoon,” the researchers explain. “From a clinical perspective, for most patients, no second set of ‘morning glasses’ is needed for near or distance vision, given the relatively small differences in refraction, and best- corrected visual acuity measured at steady state in the afternoon can be regarded as a relatively reliable assessment. [W]hen evaluating patients with Fuchs dystrophy, time since eye opening is a key parameter to account for when evaluating disease progression in clinic or for clinical trials or when scheduling patients with Fuchs dystrophy for refraction.”

Study limitations include a single center design.