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P Capris

Publications and source records attributed to P Capris.

11 recordsLinked to original sources
PubMed2000

Learning effect, short-term fluctuation, and long-term fluctuation in frequency doubling technique.

PURPOSE: To evaluate short-term and long-term fluctuations and learning effects in healthy subjects tested with the frequency doubling technique, which is based on a low spatial frequency and a high temporal frequency stimulus. METHODS: Twenty-three healthy adult subjects were consecutively recruited from volunteers, and 20 subjects finished the study. All the visual fields were assessed by the frequency doubling technique, program C-20, full threshold. The frequency doubling technique presents stimuli on a black-and-white video monitor with specialized control circuitry interfaced to a microprocessor. During program C-20, full threshold, 17 points are tested, one round point centrally and 16 square ones in the periphery up to 20 degrees of eccentricity. Each stimulus consists of a 0.25-cycle/degree sinusoidal grating undergoing a 25-Hz counterphase flicker. One eye of each patient was chosen at random. Each subject was tested once in the first session, three times in the second session, and once in the third and fourth sessions. Both short-term and long-term fluctuation were studied either as the average fluctuation value of all the points tested or as a point-to-point fluctuation. To study the learning effect, the results of the first session were compared with those of the second, the third, and the fourth sessions. RESULTS: The average mean sensitivity of the three examinations of the second session was 30.4 +/- 1.24 dB, and the average short-term fluctuation of all the subjects was 2.16 +/- 0.5 dB. The short-term fluctuation of each point tested ranged from 1.4 to 3.4 dB. The average mean sensitivity for all the sessions was 32.4 +/- 1.14 dB, with an average long-term fluctuation of 3.23 +/- 0.5 dB, and the long-term fluctuation of each tested point ranged from 2.5 to 4.4 dB. A mild learning effect was found between the first section and the others. CONCLUSION: Short-term and long-term fluctuations were similar to those known to occur with the conventional threshold perimetry when they were compared with the literature data. A learning effect was also observed and should be taken into account for the clinical use of this test.

Adult↗
PubMed2000

Comparison between relative dispersion analysis of high-pass resolution perimetry and standard threshold perimetry.

PURPOSE: To evaluate the correlation of the dispersion index (DI) of relative dispersion analysis (RDA), a new high-pass resolution perimetry (HRP) index, with other HRP indices and those of the Humphrey standard threshold perimeter (STP) parameters. METHODS: Sixty-eight eyes were randomly recruited. Thirty-one eyes were classified as glaucomatous (high intraocular pressure, abnormal visual field and/or optic disc) and 37 as ocular hypertensives (high intraocular pressure, normal visual field, normal optic disc). All the subjects were examined with Humphrey Perimeter, program 30-2, and HRP. The HRP data were also analysed with the RDA program. Statistical analysis was performed with Student's t-test, Pearson's r correlation coefficient, Mann-Whitney nonparametric test and Spearman correlation coefficient when appropriate. RESULTS: Within the entire sample significant correlations were found between the RDA index (DI) and all the HRP indices (p < 0.001) and corrected pattern standard deviation (p < 0.01), pattern standard deviation (PSD) (p < 0.01), mean deviation (p < 0.05) and short-term fluctuation (p < 0.05) of STP. A stronger correlation was found in glaucomatous patients. In subjects with ocular hypertension DI was only weakly correlated with PSD, local deviation and form index. No difference in DI was found between glaucoma and ocular hypertension. CONCLUSION: The DI of HRP has the theoretical capacity to detect localised inhomogeneity of retinal sensitivity, but at present our data do not support this hypothesis. Before any clinical applications of this index further studies are needed.

Adult↗
PubMed1999

Correlation between high-pass resolution perimetry and standard threshold perimetry in subjects with glaucoma and ocular hypertension.

PURPOSE: To evaluate the correlation between High-Pass Resolution Perimetry (HRP) and standard threshold perimetry in patients with glaucoma or ocular hypertension. METHODS: 31 glaucomatous patients and 37 ocular hypertension subjects with previous perimetric examination experience were consecutively recruited and only one eye for each patient was selected at random. Glaucomatous patients were classified as having primary open angle glaucoma when they had an abnormal visual field and/or an abnormal optic nerve head (ONH)/retinal nerve fiber layer (RNFL) typical of glaucoma, open angle at gonioscopy and no clinically apparent secondary cause for their glaucoma. Ocular hypertension subjects were defined as having intraocular pressure >21 mm Hg on no treatment, normal visual field, normal ONH and RNFL, elevated intraocular pressure without any treatment. All the subjects were examined with Humphrey Field Analyzer (HFA) 640, 'program central 30-2' (Humphrey Systems, San Leandro, CA, USA) and with High-Pass Resolution Perimeter (HRP), Ophthimus version 2.4,'ring program' (Nikon-HighTech Vision, Goteborg, Sweden). Visual field indices were obtained with both systems: for HFA mean deviation (MD), corrected pattern standard deviation (CPSD) and short term fluctuation (SF), while for HRP global deviation (GD), local deviation (LD), form index (FI) and neural capacity (NC). The data were analyzed by descriptive analysis, Student's t test with Bonferroni's correction or Mann-Whitney non-parametric test and Pearson or Spearman's correlation coefficient. RESULTS: A significant correlation was found between MD and GD (r = -0.81), CPSD and LD (r = 0.87), PSD and LD (r = 0.72). NC was significantly correlated with MD (r = 0.76), GD (r = -0.94). FI was significantly correlated with PSD (r = -0.58), CPSD (r = -0.72), LD (r = -0.56). When the same data were analyzed for the glaucomatous group only, similar results were found; in the ocular hypertensive group no significant correlation was found except between NC and MD (r = 0.52). CONCLUSION: HRP indices vary comparably with HFA indices. Parameters as NC and FI were significantly correlated with standard visual field indices of both HFA and HRP. Although the clinical applications for FI are not clear yet, NC could detect both early glaucomatous damage and age related changes.

Disease Progression↗
PubMed1985

Comparing continuous and stepwise luminance variation in static campimetry using the Grignolo-Tagliasco-Zingirian projection campimeter.

In traditional static perimetry the remarkable precision achieved, resulting mainly from the lack of temporal factors related to latency, largely makes up for the relatively long time required to perform the test. Conversely, the increase in speed of the test and in the information content of the visual field charts counteract the lower precision attained with kinetic perimetry. If the influence of the latency time on responses could be kept at a low value, then adopting a static strategy, based on a continuous rather than discrete target luminance variation for threshold detection, could be justified. For this purpose a luminance variation time sequence designed to reproduce the conditions of the traditional static perimetric test was chosen. The test was performed on the Grignolo-Tagliasco-Zingirian projection campimeter, after comparing its clinical performance with the Goldmann perimeter. These two methods - one based on continuous variation, the other based on discrete target luminance variation - were compared using a 14-subject sample. We conclude that the presentation strategy based on continuous luminance variation can be regarded as a valid alternative to the traditional method.

Adult↗
PubMedDate not supplied

Computerized system for static and kinetic automatic perimetry.

A new automatic perimeter has recently been developed under the supervision of the Perimetry Study Group of the Genoa University Eye Clinic. The main characteristics of this instrument are the following: projected targets; accurate calibration of stimulus size and shape; preliminary measurement of visual acuity and pupillary diameter; automated fixation control based on an optimized television system; static, kinetic, and mixed procedures; screening and diagnostic threshold and suprathreshold strategies; standard and non-standard parameters for stimuli, background, and procedures; user-friendly software; large disk memory for data storage and analysis.

Diagnosis, Computer-Assisted↗