Characteristics of the Optic nerve Head Topography in Narrow Angle Eye

Abstract

Abstract: : Purpose: To compare the optic nerve head topography in narrow angle eyes with that in control eyes. Methods: Twenty eyes from 20 subjects with narrow angle and 12 eyes from 12 control subjects matched for age (67.3 + 7.0 yrs vs. 71.3 + 8.7 yrs), refractive errors (0.9 + 1.6 D vs. 1.0 + 1.2 D) and the optic disc area (2.3 + 0.5 mm² vs. 2.0 + 0.3 mm²) were prospectively enrolled in the study. The narrow angle eyes had gonioscopic angles of equal to or less than grade 2 of Shaffer’s scheme without peripheral anterior synechia for whole angles, visual acuity better than 20/25, and showed no glaucomatous defects by the program SITA 30–2 of Humphrey visual field. The control eyes were recruited from those with wide–open angles, no glaucomatous defects by Humphrey visual field and no significant eye diseases excepting for mild cataract with visual acuity>20/25. The optic disc area and other optic disc parameters were measured using Heidelberg Retina Tomograph–2 (HRT). Results: The intraocular pressure at HRT imaging was 15.8 + 3.0 mmHg for narrow angle eyes and 14.0 + 2.4 mmHg for control eyes. Of HRT parameters, the rim area (1.5 + 0.3 mm²) and the rim volume (0.4 + 0.1 mm³) in the narrow angle eyes were larger than those in the control eyes (1.2 + 0.3 mm² and 0.3 + 0.1 mm³) (p<0.02, unpaired t–test). Conclusions: In narrow angle eyes, dimensions seem to be different from those of control eyes in the optic nerve head topography.

Keywords: imaging/image analysis: clinical • optic disc • anterior chamber