Equating spatial summation in visual field testing reveals greater loss in optic nerve disease.
PURPOSE
To test the hypothesis that visual field assessment in ocular disease measured with target stimuli within or close to complete spatial summation results in larger threshold elevation compared to when measured with the standard Goldmann III target size. The hypothesis predicts a greater loss will be identified in ocular disease. Additionally, we sought to develop a theoretical framework that would allow comparisons of thresholds with disease progression when using different Goldmann targets.


METHODS
The Humphrey Field Analyser (HFA) 30-2 grid was used in 13 patients with early/established optic nerve disease using the current Goldmann III target size or a combination of the three smallest stimuli (target size I, II and III). We used data from control subjects at each of the visual field locations for the different target sizes to establish the number of failed points (events) for the patients with optic nerve disease, as well as global indices for mean deviation (MD) and pattern standard deviation (PSD).


RESULTS
The 30-2 visual field testing using alternate target size stimuli showed that all 13 patients displayed more defects (events) compared to the standard Goldmann III target size. The median increase for events was seven additional failed points: (range 1-26). The global indices also increased when the new testing approach was used (MD -3.47 to -6.25 dB and PSD 4.32 to 6.63 dB). Spatial summation mapping showed an increase in critical area (Ac) in disease and overall increase in thresholds when smaller target stimuli were used.


CONCLUSIONS
When compared to the current Goldmann III paradigm, the use of alternate sized targets within the 30-2 testing protocol revealed a greater loss in patients with optic nerve disease for both event analysis and global indices (MD and PSD). We therefore provide evidence in a clinical setting that target size is important in visual field testing.
['Kalloniatis|Michael|M|', 'Khuu|Sieu K|SK|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D015350:Contrast Sensitivity D018450:Disease Progression D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D009901:Optic Nerve Diseases D015203:Reproducibility of Results D014785:Vision, Ocular D058609:Visual Field Tests D014794:Visual Fields D055815:Young Adult
spatial summation Ricco's law automated perimetry glaucoma humphrey field analyzer octopus visual field optic nerve head drusen