Abstract
Purpose: :
To develop and validate a monitor based system for Standard Automated Perimetry (SAP).
Methods: :
A novel system for SAP was developed for use on the Heidelberg Edge Perimeter (HEP). It was designed to be equivalent to the Humphrey Field Analyzer (HFA), using a Goldmann III target. A 0.43o diameter target was used for the 38dB to 16dB range. For brighter stimuli a larger target was used to give equivalence (15dB to 0 dB). To validate the approach the right eye of 10 normal subjects between the ages of 24 and 30 were tested. SAP on the HEP and HFA was performed at 12 locations (3x3, 9x9, and 15x15 for each quadrant). Neutral density filters were used to simulate defect (ND: 0, 2, 3.6 and 4). In addition, 110 normal volunteers were evaluated using both versions of SAP.
Results: :
With ND0 and ND2 SAP and HFA sensitivities were very similar, with a Mean of Differences (MoD) of 0.1dB (SD 2.13). With ND4 the MoD was 1.4dB (SD 5.26) with slightly higher sensitivities for HEP. HEP and HFA SAP demonstrated similar test-retest characteristics across age groups. The retest variance was least for the 40-49 year olds (SD: 3) and greatest for the 70-79 age group (SD: 4.2). The Limits of Agreement (95th% confidence limits) was 6.9dB when comparing SAP on the HEP and the HFA, and was similar to the Coefficient of Repeatability (95th% confidence limits for visit 2 versus visit 3) for HFA (5.8dB) and HEP (5.3dB).
Conclusions: :
SAP on the HEP produced similar results to the HFA. Both at higher dB values (>16) and lower (<15) these machines produced similar results suggesting that the HEP’s use of larger targets are equally detectable as HFA’s brighter, smaller target.
Keywords: visual fields • perimetry