Zeiss Humphrey II-i series - (E) Goldmann Conversion Tables

Humphrey Field Analyzer II- i series User Manual 2660021145640 A
Goldmann Conversion Tables
E-1
(E) Goldmann Conversion Tables
The decibel notation the Humphrey Field Analyzer II- i uses can be expressed in terms of Goldmann
units or apostilbs. The conversion between decibels (dB) and apostilbs (asb) and Goldmann units
are listed in Table E.1. For example, a threshold sensitivity of 25 dB
using a size III stimulus is equal
to a Goldmann III-ie stimulus or 32 asb. A threshold sensitivity of 0 dB using a size III stimulus is
equivalent
to a Goldmann V 4e stimulus or 10,000 asb. A simplified chart to convert from dB values
to Goldmann units is available in Tables E-1 through E-6.
To use the conversion tables, first locate the table which lists the targ
et size you used for the test.
For example, you may have completed a central 30-2 threshold test using a size III target and you
want to find out what the Goldmann equivalent is for 15 dB. Using Table E-4, find 15 dB. Read the
horizontal and vertical columns that intersect at 15 dB. The Goldmann equivalent is either a II 4e, III
3e, IV 2e, or V 1e.
Stimulus Size Angular Subtense
(degrees)
Stimulus Area (30 cm Bowl)
(mm2)
Size I 0.11 1/4
Size II 0.22 1
Size III 0.43 4
Size IV 0.86 16
Size V 1.72 64