Test-Retest Variability for Semi-Automated Kinetic Perimetry and GATE Static Perimetry in Retinitis Pigmentosa

Abstract

 

Purpose

 

Visual fields provide information essential for clinical evaluation of patients with inherited retinal degenerations and serve as endpoints for clinical trials. We present test-retest variability data for static and kinetic perimetry in patients with retinitis pigmentosa (RP).

 

Methods

 

Semi-automated Kinetic Perimetry (SKP) and German Adaptive Thresholding Estimation (GATE) static perimetry (GSP) were performed on 32 patients with RP on 3 sessions using Octopus 900 perimeter (Haag-Streit, Köniz, Switzerland). The solid angles (degrees²) subtended by three isopters (V4e, III4e, I4e) were measured. Full-field static perimetry used the GATE strategy, Goldmann stimulus size V, and a centrally condensed grid of 164 points extending from 56° nasally to 80° temporally. Visual Field Modeling and Analysis software fit the sensitivity data to a thin-plate spline to create 3-dimensional models of the Hill of Vision (HOV), from which the sensitivity volume (dB-sr) for the total field (HOVTotal) and the central 30° field (HOV30°) were independently measured for test and re-test sessions using the 1st pair of sessions for each subject. The average age at first session was 52.8 yrs (SD=9.4, range 36.9 to 70.9 years).

 

Results

 

Differences between sessions for both kinetic and static variables tended to be greater for larger session values. As seen in the table, the coefficients of variation for within subject differences were fairly similar for SKP and GSP, ranging from 0.06 to 0.13 for SKP and 0.10 to 0.14 for GSP. The findings appear comparable to other reports.

 

Conclusions

 

The test-retest variability for SKP and GSP support their use as endpoints for clinical trials.

 

 

CV is coefficient of variation of within subject differences obtained as within subject SD divided by mean.

 

Keywords: 462 clinical (human) or epidemiologic studies: outcomes/complications • 696 retinal degenerations: hereditary • 758 visual fields