Age-related nonparalytic hypertropia: Clinical features

Age-related nonparalytic hypertropia (ARNH) is reported to be involved in sagging eye syndrome, where excyclotorsion is large and the lower eye is more extorted. The primary aim of this study was to describe the clinical profiles of patients with ARNH. The secondary aim was to compare cyclotorsion in patients with ARNH with that in normal individuals.

Inclusion criteria for ARNH were insidious onset of diplopia at distance after 50 years of age, nonparalytic hyperdeviation and follow-up >6 months. Objective cyclotorsion was measured as the disc-to-fovea angle (DFA) on fundus photographs obtained from two groups: 75 patients with ARNH (age, 74.1 ± 7.9 years) and 75 sex- and age-matched normal controls (73.9 ± 8.1 years).

The hypertropia angle was 4.6 ± 2.8 prism dioptres. One patient also experienced diplopia at near-gaze. DFA in ARNH (right/left eye; 11.0 ± 4.8°/11.6 ± 3.9°) was larger than that of the control (6.6 ± 3.7°/9.2 ± 3.5°) (p < 0.0001). The DFA in the non-dominant eye (12.5 ± 4.1°) was larger than that in the dominant eye (10.2 ± 4.3°) (p = 0.0003). The lower eye did not have the larger DFA in 29 patients.

The angle of hyperdeviation in patients with ARNH was small. The DFA in the ARNH group was larger than that in the normal group. The lower eye was not the eye with a larger DFA in 39% of ARNH, inconsistent with sagging eye syndrome. Decreased phoria adaptation (fusional ability) may trigger diplopia in patients with ARNH.