A mathematical description of nerve fiber bundle trajectories and their variability in the human retina.

We developed a mathematical model wherein retinal nerve fiber trajectories can be described and the corresponding inter-subject variability analyzed. The model was based on traced nerve fiber bundle trajectories extracted from 55 fundus photographs of 55 human subjects. The model resembled the typical retinal nerve fiber layer course within 20 degrees eccentricity. Depending on the location of the visual field test point, the standard deviation of the calculated corresponding angular location at the optic nerve head circumference ranged from less than 1 degrees to 18 degrees , with an average of 8.8 degrees .

The use of semi-automated kinetic perimetry (SKP) to monitor advanced glaucomatous visual field loss.

PURPOSE: (i) To compare visual field (VF) results obtained with semi-automated kinetic perimetry (SKP) and automated static perimetry (ASP) in patients with advanced glaucomatous VF loss, (ii) to evaluate test-retest reliability of SKP and ASP and (iii) to assess patients' preference for SKP and ASP. METHODS: Twenty eyes of 20 patients (11 male, 9 female, aged 38 to 83 years) with advanced glaucomatous VF loss (stage III or IV according to the Aulhorn classification). Each of the 20 patients were examined in 4 sessions every 3 months with SKP (Goldmann stimulus III4e, I4e and at least one additional dimmer stimulus, within the 90 degrees visual field) and ASP within the 30 degrees VF, employing a threshold-related, supra-threshold test strategy with high spatial resolution for the same instrument (Octopus 101 perimeter, Haag-Streit Inc., Koeniz, Switzerland). RESULTS: Visual field areas (VFA) were compared by analyses of covariance (ANCOVA) with co-variable time, patient effect and their interaction. Test-retest reliability was assessed by ratios (R) of intersection and union of VFA: The mean VFA within the 30 degrees of VF at baseline was 2,344 square degrees (deg(2)) with SKP (Goldmann stimulus III4e) and 1,844 deg(2) with ASP. The patients showed stable visual fields for both SKP and ASP. Comparison of SKP with ASP of the same sessions revealed a median ratio of intersection and union of VFA of 0.78 with the III4e stimulus and of 0.79 with the I4e stimulus. When follow-up SKPs were compared with baseline SKPs the median of the ratios was between 0.80 and 0.93 for the different isopters. The corresponding ratio of ASP's follow-up and baseline VFs was 0.81 (with the size III static stimulus). Nineteen of 20 patients preferred kinetic perimetry to static perimetry. CONCLUSIONS: The comparability between SKP and ASP is satisfactory and within the range of the test-retest reliability of ASP. SKP shows slightly better test-retest reliability than ASP. The majority of patients with advanced glaucomatous visual field loss prefer SKP instead of ASP. SKP is a valuable alternative to ASP in monitoring advanced glaucomatous visual field loss.

Visual field defects in acute optic neuritis--distribution of different types of defect pattern, assessed with threshold-related supraliminal perimetry, ensuring high spatial resolution.

PURPOSE: To assess the pattern and the local spatial frequency distribution of visual field defects (VFDs) in eyes with clinically diagnosed optic neuritis (ON) and their currently unaffected fellow eyes, using threshold-related, slightly supraliminal perimetry, ensuring high spatial resolution. METHODS: Records obtained with the Tübingen Automatic perimeter (TAP, Oculus Inc., Dudenhofen, Germany) and the Octopus 101 perimeter (Haag-Streit Inc, Koeniz, Switzerland), using a standardized grid of 191 static targets within the central 30 degrees visual field, were analysed retrospectively. VFDs were assigned to 15 classes. RESULTS: Visual fields (VF) from 99 patients (26 male and 73 female subjects, aged from 18 to 51 years) with clinically diagnosed, acute ON (52 right eyes, 48 left eyes affected, one bilateral involvement) were evaluated. Central scotomas were the most common finding in associated eyes, covering 41% of all VFDs in affected eyes. Nerve fibre bundle defects were found in 29% and paracentral scotomas in 14% of all VFDs. Fellow eyes were perimetrically normal in 65% of the clinically monocular ONs. Nerve fibre bundle defects were found in 21% and diffuse scotomas in 9% of the fellow eyes. CONCLUSIONS: Central scotomas and retinal nerve fibre bundle defects are the most common VFDs in acute ON. Small central and paracentral scotomas that most probably would have been missed by automated thresholding perimetry with its relatively coarse grid could be detected by threshold-related, slightly supraliminal strategy. Of the fellow eyes in clinically apparent monocular optic neuritis, 35% present with visual field defects.

Evaluation of glaucomatous visual field loss with locally condensed grids using fundus-oriented perimetry (FOP).

PURPOSE: We compared detection rates of glaucomatous visual field defects (VFDs) between a conventional rectangular stimulus grid and locally condensed test point arrangements in morphologically suspicious regions. METHODS: Humphrey Field Analyzer model 630 (HFA I, program 30-2 with a rectangular 6 degrees x 6 degrees grid) was used as the conventional perimetric method. Individual local test-point condensation was realized by fundus-oriented perimetry (FOP) on the Tuebingen Computer Campimeter (TCC). RESULTS: Of a total of 66 glaucoma patients, or suspected sufferers, 23 showed normal findings and 27 showed pathological findings with both methods. In 15 cases we found normal visual fields in HFA 30-2, whereas FOP revealed early glaucomatous functional damage. Only one case showed pathological HFA results, while FOP was normal. Detection rates of VFDs significantly differed between the two methods (p < 0.001; sign test). CONCLUSIONS: FOP, using individually condensed test grids, significantly increases detection rates of glaucomatous VFDs in morphologically suspicuous areas compared with a conventional HFA 30-2 technique using equidistant rectangular (6 degrees x 6 degrees) test point arrangements.

[Evaluation of extensive visual field defects with computer-assisted kinetic perimetry]. / Evaluation ausgedehnter Gesichtsfelddefekte mittels computerassistierter kinetischer Perimetrie.

BACKGROUND: Conventional kinetic perimetry is of especial use in case of advanced scotoma. However, examiner dependency is a major drawback. Purpose of this study was to evaluate the clinical feasibility and intraindividual scatter of computer-assisted kinetic perimetry in monitoring advanced visual field defects of various origins. METHODS: Examinations were carried out with the Tuebingen Computer Campimeter (background lumincance 10 cd/m2). In an initial session, the localization of the scotoma border is estimated with conventional manual kinetic perimetry. In the subsequent computer assisted kinetic mode, an individually adjusted set of vectors is designed. Each vector crosses the manually assessed visual field defect border almost perpendicularly, starting approximately 3 degrees within the scotoma. Each individual set of vectors can be stored and recalled for follow-up. Stimuli move along these vectors with identical characteristics as in manual kinetic perimetry. Stimulus presentations are repeated six times in a randomized order. Patients' responses are recorded and additionally corrected for mean individual reaction time. A "local kinetic threshold" (mean) and a related parameter for dispersion (standard deviation) are assessed. RESULTS: Four subjects with advanced visual field loss of various origin (retinitis pigmentosa, vigabatrin-associated visual field defect, glaucomatous nerve fibre layer defect, and postgeniculate visual pathway defect) participated in this study. Maximal difference between manual-kinetic and automated kinetic thresholds reaches from 1.7 degrees to 5 degrees. Local scatter (standard deviation) of kinetic threshold, assessed by computer-assisted perimetry, varies between 0.1 degree and 3.0 degrees. CONCLUSION: Computer assisted kinetic perimetry is a new, useful, examiner-independent, reliable method for effective evaluation and monitoring of advanced visual field loss.