Zeiss Humphrey II-i series, User Manual

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Humphrey Field Analyzer II-
i
series User Manual 2660021145640 A
Guided Progression Analysis (GPA) 8-3
GPA Was Clinically Developed
GPA relies on detailed empirical knowledge of the threshold visual field variability that typically is
found in everyday glaucoma patients. Two tests are averaged to establish a Baseline, and up to
fourteen (14) Follow-up tests may be compared to the Baseline. Those fields that repeatedly and
consistently show changes exceeding what is known to represent the expected range of test-retest
variability are identified as having possible or likely progressive visual field loss.
Precisely quantifying the actual range of variability was critical to the development of GPA. Hundreds
of glaucoma patients, covering the full disease spectrum from early to advanced glaucoma, were
enrolled at numerous centers worldwide. Each patient attended clinic four times in the space of one
month, and underwent three visual field tests at each visit—one using SITA Fast, one using SITA
Standard, and one using the Full Threshold strategy. Variations seen from visit to visit were used to
define the expected and normal test-retest reproducibility for glaucomatous visual fields.
GPA Is Easy To Use
GPA is Designed for Compatibility and Flexibility
A major GPA design goal was to simplify the process of incorporating progression analysis into
everyday practice. The GPA is compatible with SITA Standard, SITA Fast and Full Threshold testing
strategies. Your GPA software uses your current database of patient test results.
GPA Provides Automated Exam Selection
The GPA software is designed for easy use and implementation. Default test selection is automated.
To assist you in getting exactly the analysis you want, you may modify the test selection at any time.
Once GPA is set up for a patient, the software retains the settings and produces a new analysis after
every new SITA Follow-up exam.
GPA Verifies Exam Reliability
The GPA software is designed to account for and compensate for random patient variability; however,
high quality exams produce the best analysis. If the Fixation Loss reliability index exceeds acceptable
tolerances, the GPA software will warn you by generating and printing out a **Low Test Reliability**
message (see
Figure 8.4 ). Tests showing excessive False Positive response rates (15% or greater) are
automatically excluded from GPA analysis and are marked with an exclamation point (“!”) in the
Exam Selection dialog. The printout will include the notation “*** Excessive High False Positives ***”.
GPA Is Easy To Understand
GPA Features Familiar and Simple Reports
GPA reports are designed to look very similar to your other HFA printouts. The Full GPA report is
based on the familiar Overview format and includes a Graytone Plot, a Pattern Deviation Plot,
Deviation from Baseline Plot, a Progression Analysis Probability Plot and key global indices such as
MD, PSD, and VFI (see
“Global Indices,” on page 7-7 for a description of the VFI index). The Single
Field Analysis printout (SFA GPA) incorporates a GPA Progression Analysis Probability Plot. The GPA
Summary, Full GPA, and GPA Last 3 Follow-up reports also include the VFI Plot—an
easy-to-interpret trend analysis of the overall visual field, featuring the new VFI index.