Morning Myopic Shift and Glare in Advanced Fuchs Endothelial Corneal Dystrophy

Impaired subjective morning visual acuity with improvement of symptoms during the day is pathognomonic for corneal endothelial dysfunction in advanced Fuchs endothelial corneal dystrophy (FECD). This study aimed to analyze the daily fluctuations of corneal thickness, refraction, and (glare) visual acuity in advanced FECD.

Prospective cohort study.

Patients with advanced FECD (FECD group) and patients with normal cornea (control group) were enrolled. Routine clinical examination was performed using slit-lamp biomicroscopy, funduscopy, and macular optical coherence tomography. In addition, assessment using corneal Scheimpflug tomography (Pentacam), refraction, corrected distance visual acuity (CDVA), and glare CDVA was performed at 4 PM (afternoon) and the following day at 8 AM (morning).

A total of 29 FECD eyes and 22 control eyes were included. Diurnal variations from afternoon to morning were Δ corneal thickness (apex) ± standard deviation (SD) 41.45 ± 34.1 μm (P < .001, FECD group) and 5.5 ± 6.72 μm (P = .001, control group); Δ spherical equivalent ± SD -0.64 ± 0.6 diopters (D) (P < .001, FECD group) and -0.01 ± 0.50 D (P = .461, control group); Δ total corneal refractive power ± SD 0.60 ± 0.83 D (P = .001, FECD group) and -0.01 ± 0.49 D (P = .602, control group), Δ CDVA ± SD 0.15 ± 0.18 logarithm of minimal angle of resolution (logMAR) (P < .001, FECD group) and 0.02 ± 0.04 logMAR (P = .174, control group), Δ CDVA glare ± SD 0.34 ± 0.25 logMAR (P < .001, FECD group) and 0.05 ± 0.11 logMAR (P = .106, control group).

A morning myopic shift and increased glare paralleling increased corneal thickness may particularly contribute to subjective visual impairment in advanced FECD in the first hours after awaking. This should be taken into account during assessment and surgical decision-making in patients with FECD.