Variance components for PIMD‐2π estimation of the optic nerve head and consequences in clinical measurements of glaucoma

• Purpose To estimate the sources of variation for Pigment epithelium central limit-Inner limit of the retina Minimal Distance averaged over 2 pi (PIMD-2 pi), and further to analyse their consequences for clinical measurements of glaucoma. Methods Forty subjects with early to moderate stage glaucoma were included. Three SD-OCT volumes of the optic nerve head (ONH) were captured at two occasions. Each volume was segmented three times for PIMD-2 pi. The magnitude of the sources of variation for PIMD-2 pi measurements was estimated with an analysis of variance. Results A 95% confidence interval for mean PIMD-2 pi was estimated to 215 +/- 12 mu m (df = 38). The estimated variance for subjects was 1280 mu m(2). The within-subject estimated variance for occasions, volumes and segmentations was 10 mu m(2), 30 mu m(2) and 40 mu m(2), respectively. The within-subject variances were used to model follow-up of PIMD-2 pi over time. A linear loss rate of 0.05 of baseline PIMD-2 pi/year was assumed. A significant PIMD-2 pi change could be detected in approximately 16-18 months with evenly spaced visits every 4 or 6 months. Conclusions Due to the small within-subject estimated variances, a clinically undesirable PIMD-2 pi change from baseline can be detected in approximately 18 months. Detection of significant PIMD-2 pi loss in a subject requires knowledge of normal age loss and measurement variability.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Oftalmologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Ophthalmology (hsv//eng)

Keyword

glaucoma

oct

optic nerve head

PIMD

follow-up

Ophtalmology

Oftalmiatrik

Publication and Content Type

ref (subject category)

art (subject category)