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E. Blumen–Ohana, M. Mesbah, G. Berdeaux, J.–P. Nordmann; Scoring of Visual Field Measured Through Humphrey Perimetry: Cluster Analysis Based Upon Anatomical and Clinical Characteristics in Glaucoma Patients . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3978.
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© ARVO (1962-2015); The Authors (2016-present)
To extract unidimensional, well–separated latent scores that are anatomically and clinically valid from 52 standardized variables collected by Humphrey visual field perimetry.
Visual field data of 437 patients were collected and classified by a glaucoma specialist into seven clinical groups: irregularities of visual field, nasal step, arcuate scotoma, paracentral scotoma, blind–spot enlargement, diffuse deficit and advance deficit. The number and content of constituent variable scores were identified by principal components analysis followed by Varimax Rotation and simple clustering, taking spatial distribution homogeneity and visual system anatomy into account. Unidimensionality was checked by a stepwise Cronbach α curve. Clinical predictability of the derived scores was checked by comparing clinical groups (ANOVA).
Patients older than 60 years comprised 53,3% of the sample. The average mean deviation was –9,2 dB and pattern standard deviation was 6,5dB. Six scores were identified ! four peripheral scores (nasal superior, nasal inferior, temporal superior, temporal inferior) and two paracentral scores superior and inferior. Cronbach α was always >0,90. The six scores decreased sequentially from irregularities of visual field to diffuse deficit to advanced deficit. Scores of arcuate scotoma were lower in nasal superior, nasal inferior and temporal superior; Paracentral score superior was less in paracentral scotoma; blind–spot enlargement scores were less in temporal superior and temporal inferior; nasal step scores were less in nasal superior and nasal inferior.
Six well–separated, optimal scores were obtained from the Humphrey perimetry matrix. Internal reliability was good. It was possible to discriminate between clinical sub–groups. Further analyses, based on longitudinal data, must be performed to confirm these findings.
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