Test-retest variability of frequency-doubling perimetry and conventional perimetry in glaucoma patients and normal subjects.
(1/1197)
PURPOSE: To compare the test-retest variability characteristics of frequency-doubling perimetry, a new perimetric test, with those of conventional perimetry in glaucoma patients and normal control subjects. METHODS: The study sample contained 64 patients and 47 normal subjects aged 66.16+/-11.86 and 64.26+/-7.99 years (mean +/- SD), respectively. All subjects underwent frequency-doubling perimetry (using the threshold mode) and conventional perimetry (using program 30-2 of the Humphrey Field Analyzer; Humphrey Instruments, San Leandro, CA) in one randomly selected eye. Each test was repeated at 1-week intervals for five tests with each technique over 4 weeks. Empirical 5th and 95th percentiles of the distribution of threshold deviations at retest were determined for all combinations of single tests and mean of two tests, stratified by threshold deviation. The influence of visual field eccentricity and overall visual field loss on variability also were examined. RESULTS: Mean test time with frequency-doubling perimetry in patients and normal control subjects was 5.90 and 5.25 minutes, respectively, and with conventional perimetry was 17.20 and 14.01 minutes, respectively. In patients, there was a significant correlation between the results of the two techniques, in the full field and in quadrants, whereas in normal subjects there was no such correlation. In patients, the retest variability of conventional perimetry in locations with 20-dB loss was 120% (single tests) and 127% (mean tests) higher compared with that in locations with 0-dB loss. Comparative figures for frequency-doubling perimetry were 40% and 47%, respectively. Variability also increased more with threshold deviation in normal subjects tested with conventional perimetry. In both patients and normal subjects, variability increased with visual field eccentricity in conventional perimetry, but not in frequency-doubling perimetry. Both techniques showed an increase in variability with overall visual field damage. CONCLUSIONS: Frequency-doubling perimetry has different test-retest variability characteristics than conventional perimetry and may have potential for monitoring glaucomatous field damage. (+info)
Evaluation of focal defects of the nerve fiber layer using optical coherence tomography.
(2/1197)
OBJECTIVE: To analyze glaucomatous eyes with known focal defects of the nerve fiber layer (NFL), relating optical coherence tomography (OCT) findings to clinical examination, NFL and stereoscopic optic nerve head (ONH) photography, and Humphrey 24-2 visual fields. DESIGN: Cross-sectional prevalence study. PARTICIPANTS: The authors followed 19 patients in the study group and 14 patients in the control group. INTERVENTION: Imaging with OCT was performed circumferentially around the ONH with a circle diameter of 3.4 mm using an internal fixation technique. One hundred OCT scan points taken within 2.5 seconds were analyzed. MAIN OUTCOME MEASURES: Measurements of NFL thickness using OCT were performed. RESULTS: In most eyes with focal NFL defects, OCTs showed significant thinning of the NFL in areas closely corresponding to focal defects visible on clinical examination, to red-free photographs, and to defects on the Humphrey visual fields. Optical coherence tomography enabled the detection of focal defects in the NFL with a sensitivity of 65% and a specificity of 81%. CONCLUSION: Analysis of NFL thickness in eyes with focal defects showed good structural and functional correlation with clinical parameters. Optical coherence tomography contributes to the identification of focal defects in the NFL that occur in early stages of glaucoma. (+info)
The optic disc in glaucoma. I: Classification.
(3/1197)
Five different descriptive types of glaucomatous optic discs are described, based on the examination of X2 magnification stereophotographs of 252 patients from the files of the Glaucoma Service at Wills Eye Hospital. The method of analysis is described in detail. These types include: overpass cupping, cupping without pallor of the neuroretinal rim, cupping with pallor of the neuroretinal rim, focal notching of the neuroretinal rim, and bean-pot cupping. These morphological types may be caused by variations in factors contributing to the pathogenesis of glaucomatous eyes. Recognition of these differing types may help in determining the factors in each case. (+info)
Asymmetry in optic disc parameters: the Blue Mountains Eye Study.
(4/1197)
PURPOSE: To examine asymmetry in vertical optic disc parameters among subjects classified as normal, as having ocular hypertension (OH), and as having open-angle glaucoma (OAG) in a population-based sample. METHODS: The Blue Mountains Eye Study examined 3654 people aged 49 to 97 years, including 2929 normal subjects, 118 with OH, and 79 with OAG in the groups of interest for the asymmetry study. Optic disc parameters were measured in a masked manner from stereo optic disc photographs. RESULTS: Vertical disc diameter asymmetry (the absolute value of left minus right disc diameters) was similar among normal, OH, and OAG groups (median, 0.07-0.08 mm). Vertical cup- disc ratio asymmetry was higher in patients with OAG (median, 0.11) than in normal subjects (median, 0.06; P < 0.0001) and in those with OH (median, 0.05; P < 0.0001) but was similar between normal subjects and patients with OH (P = 0.17). A cup- disc ratio asymmetry of 0.2 or more was found in 24% of patients with OAG, compared with 1% of patients with OH and 6% of normal subjects. Corresponding rates for cup- disc ratio asymmetry of 0.3 or more in these three groups were 10%, 0%, and 1%, respectively. Using multiple linear regression, cup-disc ratio asymmetry was associated with disc diameter asymmetry and intraocular pressure asymmetry. However, these two factors explained only 3% of the variability of cup- disc ratio asymmetry and 20% of cup diameter asymmetry. CONCLUSIONS: Despite differences between the OAG group and either the OH or normal groups, asymmetry alone was not useful in identifying patients with OAG. At all levels of asymmetry, subjects were more likely to be classified as normal than with OH or OAG. (+info)
Effect of aging on optic nerve appearance: a longitudinal study.
(5/1197)
AIM: To determine whether aging causes detectable changes in the appearance of the optic disc. METHODS: A retrospective longitudinal study was performed with quantitative and qualitative evaluations of digitised stereoscopic optic disc photographs of 224 eyes of 224 subjects. There were three groups: 100 normal subjects from the Framingham Eye Study, 68 glaucomatous patients followed longitudinally, and 56 normal subjects and glaucoma patients who had separate sets of disc photos taken on the same day. A disc was considered qualitatively worse if two of three experienced observers agreed that it was worse. Quantitative progression was defined as a >10% decrease in rim/disc area ratio measured with computer assisted planimetry. RESULTS: With quantitative evaluation, normal eyes (mean follow up 13 years) and same day eyes displayed no statistically significant difference in change of rim/disc area ratios (p=0.095), nor in the number of discs that progressed-five of 100 (5%) v two of 56 (4%) respectively. Glaucomatous eyes (mean follow up 9 years) showed a quantitative loss of disc rim in 24 of 68 (35%), and differed significantly from the normal eyes both in the change of rim/disc area ratio (p<0.0005) and number of discs that progressed (p<0.0005). With qualitative evaluation, the number of progressive discs in the glaucomatous eyes (31%) differed significantly (p<0. 0005) from the normal eyes (3%) and the same day eyes (0%). CONCLUSIONS: Over a period of follow up appropriate for long term outcome studies in glaucoma, there was no quantitatively or qualitatively detectable neuroretinal rim loss in normal aging optic nerves with stereoscopic optic disc photographs. (+info)
Estimation of the retinal nerve fibre layer thickness in the papillomacular area of long standing stage IV macular holes.
(6/1197)
AIM: To compare the thickness of the retinal nerve fibre layer (RNFL) in the papillomacular area of patients with long standing stage IV macular holes with age matched controls, using a scanning laser polarimeter. METHODS: The nerve fibre analyser (NFA) was used to measure the mean thickness of the RNFL around the optic nerve head, the thickness values of temporal and nasal 45 degrees sectors and the integral values in 10 patients with macular holes and in 10 age matched controls. RESULTS: The mean RNFL thickness around the optic nerve head was 79.71 (SD 15.06) microm in the macular hole group and 75.1 (10.8) microm in the control group (p = 0.44). The mean thickness in the temporal sector was 63.69 (12.08) microm in the macular hole group and 58.65 (8.9) microm in the control group (p = 0.3). The mean ratio between the temporal and nasal sector thickness values was 0.8441 in the macular hole group and 0.7819 in the controls (p = 0.42). CONCLUSIONS: There was no significant difference in the thickness of the RNFL in the papillomacular area in the two groups. This suggests that there may be no changes in the thickness of the RNFL in patients with long standing macular holes. (+info)
Effects of nilvadipine, a calcium antagonist, on rabbit ocular circulation and optic nerve head circulation in NTG subjects.
(7/1197)
PURPOSE: To study the effects of nilvadipine, a Ca2+ antagonist, on tissue circulation in the optic nerve head (ONH), choroid, and retina in rabbits and on the ONH circulation in normal tension glaucoma (NTG) patients. METHODS: Nilvadipine (3.2 microg/kg) or vehicle solution was injected intravenously into urethane-anesthetized rabbits, and the normalized blur value (NB), a quantitative index of in vivo tissue blood velocity, was measured in the choroid and in an area of the ONH and retina free of visible surface vessels before and for 90 minutes after injection, using the laser speckle method. The effects of nilvadipine on the ONH circulation was also studied using the H2 gas clearance method in separate groups of rabbits. Oral nilvadipine (4 mg/d) or placebo was administered to NTG patients in a double-masked manner, and NB in an area of the ONH rim free of visible surface vessels was measured by the same method before and 2, 4, 8, and 12 weeks after administration. RESULTS: The NB obtained from the ONH, choroid, or retina during the experimental period was increased by approximately 10% to 25% in the nilvadipine group compared with the NB in the control group (P < 0.0001, ANOVA), although systemic condition parameters and intraocular pressure (IOP) showed no significant intergroup difference except for a transient decrease in blood pressure in the nilvadipine groups. Blood flow rate in the ONH determined by the H2 gas clearance method also showed an approximately 25% increase in the nilvadipine group. The NB in the ONH of the oral nilvadipine-treated patients was significantly increased, by approximately 20% compared with the placebo-treated patients throughout the follow-up period. No significant intergroup difference was seen in blood pressure, pulse rate, or IOP. CONCLUSIONS: Nilvadipine increased blood velocity and, probably, blood flow in the ONH, choroid, and retina of rabbits. It also increased blood velocity in the ONH of NTG patients. (+info)
Inter- and intraobserver variation in the analysis of optic disc images: comparison of the Heidelberg retina tomograph and computer assisted planimetry.
(8/1197)
AIMS: The development of imaging and measurement techniques has brought the prospect of greater objectivity in the measurement of optic disc features, and therefore better agreement between observers. The purpose of this study was to quantify and compare the variation between observers using two measurement devices. METHODS: Optic disc photographs and images from the Heidelberg retina tomograph (HRT) of 30 eyes of 30 subjects were presented to six observers for analysis, and to one observer on five separate occasions. Agreement between observers was studied by comparing the analysis of each observer with the median result of the other five, and expressed as the mean difference and standard deviation of differences between the observer and the median. Inter- and intraobserver variation was calculated as a coefficient of variation (mean SD/mean x 100). RESULTS: For planimetry, agreement between observers was dependent on observer experience, for the HRT it was independent. Agreement between observers (SD of differences as a percentage of the median) for optic disc area was 4.0% to 7.2% (planimetry) and 3.3% to 6.0% (HRT), for neuroretinal rim area it was 10.8% to 21.0% (planimetry) and 5.2% to 9.6% (HRT). The mean interobserver coefficient of variation for optic disc area was 8.1% (planimetry) and 4.4% (HRT), for neuroretinal rim area it was 16.3% (planimetry) and 8.1% (HRT), and (HRT only) for rim volume was 16.3%, and reference height 9.1%. HRT variability was greater for the software version 1.11 reference plane than for version 1.10. The intraobserver coefficient of variation for optic disc area was 1.5% (planimetry) and 2.4% (HRT), for neuroretinal rim area it was 4.0% (planimetry) and 4.5% (HRT). CONCLUSIONS: Variation between observers is greatly reduced by the HRT when compared with planimetry. However, levels of variation, which may be clinically significant, remain for variables that depend on the subjective drawing of the disc margin. (+info)