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R P LeBlanc

Publications and source records attributed to R P LeBlanc.

At least 19 recordsLinked to original sources
PubMed2005

Central corneal thickness and progression of the visual field and optic disc in glaucoma.

AIMS: To determine whether central corneal thickness (CCT) is a significant predictor of visual field and optic disc progression in open angle glaucoma. METHODS: Data were obtained from a prospective study of glaucoma patients tested with static automated perimetry and confocal scanning laser tomography every 6 months. Progression was determined using a trend based approach called evidence of change (EOC) analysis in which sectoral ordinal scores based on the significance of regression coefficients of visual field pattern deviation and neuroretinal rim area over time are summed. Visual field progression was also determined using the event based glaucoma change probability (GCP) analysis using both total and pattern deviation. RESULTS: The sample contained 101 eyes of 54 patients (mean (SD) age 56.5 (9.8) years) with a mean follow up of 9.2 (0.7) years and 20.7 (2.3) sets of examinations every 6 months. Lower CCT was associated with worse baseline visual fields and lower mean IOP in the follow up. In the longitudinal analysis CCT was not correlated with the EOC scores for visual field or optic disc change. In the GCP analyses, there was a tendency for groups classified as progressing to have lower CCT compared to non-progressing groups. In a multivariate analyses accounting for IOP, the opposite was found, whereby higher CCT was associated with visual field progression. None of the independent factors were predictive of optic disc progression. CONCLUSIONS: In this cohort of patients with established glaucoma, CCT was not a useful index in the risk assessment of visual field and optic disc progression.

Adult↗
PubMed2001

Optic disc and visual field changes in a prospective longitudinal study of patients with glaucoma: comparison of scanning laser tomography with conventional perimetry and optic disc photography.

OBJECTIVE: To investigate the relationship between optic disc changes measured with scanning laser tomography and those measured with conventional perimetry and optic disc photography. METHODS: In a prospective longitudinal study, we followed up 77 patients with early glaucomatous visual field damage. Scanning laser tomography (using the Heidelberg Retina Tomograph) and conventional perimetry (using the Humphrey Field Analyzer) were carried out every 6 months. Disc progression was determined by a procedure recently described by us for scanning laser tomography, with confirmed progression requiring repeatable changes based on probability limits for both the depth (using individual test-retest variability values) and size of change (determined in a group of 37 healthy individuals also followed up prospectively). Field progression was determined with the Statpac Glaucoma Change Probability Analysis. The agreement between scanning laser tomography and conventional disc photography was determined in a subgroup of patients. RESULTS: Patients were followed up for a median of 5.5 years, with a median of 12 sets of examinations with scanning laser tomography and conventional perimetry. Twenty-one patients (27%) showed no progression with either technique. Thirty-one patients (40%) progressed with scanning laser tomography only, while 3 (4%) progressed with conventional perimetry only. Of the 22 patients (29%) who progressed with both techniques, 10 (45%) progressed with scanning laser tomography first (median, 18 month earlier) and 9 (41%) with conventional perimetry first (median, 12 months earlier), while 3 (14%) progressed at the same time. Of the 16 patients with disc photographs that closely overlapped the follow-up, there was concordance between scanning laser tomography and disc photography in 13 patients (81%). CONCLUSIONS: Glaucomatous disc changes determined with scanning laser tomography occur more frequently than field changes. Most patients with field changes also had disc changes; however, less than half of those with disc changes had field changes.

Adult↗
PubMed2001

Scanning laser polarimetry in a selected group of patients with glaucoma and normal controls.

PURPOSE: To evaluate the ability of scanning laser polarimetry to discriminate between subjects with glaucoma with specific patterns of visual field defect and normal controls. METHODS: This cross-sectional, prospective study in a glaucoma practice, focused on subjects with glaucoma with predefined types of visual field defect, including advanced (group A, n = 14), localized (group L, n = 46), or mixed (diffuse and localized) defects (group M, n = 22) and normal controls (n = 32). Scanning laser polarimetry was performed in one study eye per subject. Two methods of analysis were used: a subjective analysis, in which examination printouts with the image of the optic disk manually blocked were classified by two observers masked to the diagnosis, and a logistic regression analysis of the retardation parameters included in the printouts. RESULTS: The observers correctly identified 97% of the controls and 68% of subjects with glaucoma (overall correct classification of 77%), with 93%, 70%, and 47% of patients from groups A, L, and M, respectively, being correctly identified. The best discrimination obtained with the logistic regression correctly identified 69% of controls and 94% of glaucoma subjects (overall correct classification of 87%). The performance was only slightly better for cases from group A compared with L and M. CONCLUSIONS: Subjective assessment of the scanning laser polarimetry standard printout of single eyes might not be sensitive enough to detect cases of glaucoma with localized or milder mixed types of visual field defect. The discriminating ability of scanning laser polarimetry improves slightly when logistic regression analysis is employed.

Cross-Sectional Studies↗
PubMed2001

Agreement among clinicians in the recognition of patterns of optic disk damage in glaucoma.

PURPOSE: To determine the interobserver and intraobserver agreement in the recognition of different patterns of glaucomatous optic disk damage and evaluate if these patterns changed over time in patients followed for a number of years. METHODS: Patients with early to moderate glaucoma (n = 105) were consecutively enrolled to participate in a prospective observational study. In the first part of the present study, optic disk photographs obtained closest to patient's entry date in the prospective study were classified in a masked fashion by three observers according to the pattern of optic disk damage into one of the following: (1) focal, (2) myopic, (3) senile sclerotic, (4) concentric cup enlargement, (5) normal appearance, or (6) miscellaneous (those disks that did not qualify for any of the other groups). The observers were also asked to assign a confidence score for each classification, ranging from 1 (low confidence) to 5 (highest confidence). The three observers reclassified the photographs after a minimal period of 2 months, in order to assess intraobserver agreement. In a second part of the study, one observer reviewed, in a masked fashion, all the optic disk photographs that had been taken during the routine follow-up of the 105 patients in order to evaluate whether the classification of disk pattern changed over time. RESULTS: Intraobserver agreement yielded kappa values (95% confidence interval [CI]) from 0.51 (CI, 0.40 to 0.62) to 0.85 (CI, 0.77 to 0.93) depending on the observer. Interobserver agreement kappa values between all three observers was 0.40 (CI, 0.35 to 0.46), but it improved if photographs classified with moderate or higher degrees of confidence were included (0.52 [CI, 0.44 to 0.60]). During a mean follow-up period of 8.2 +/- 4.8 years, 41.6% of the eyes were always classified into the same group and 23.6% of the eyes were classified at least once into two or more of the four patterns of damage (groups 1 to 4). CONCLUSIONS: Intraobserver agreement on the pattern of optic disk damage was generally very good, with some variation among the observers. Interobserver agreement was reasonable and increased proportionally with the confidence in the classification. During long-term follow-up, the pattern of optic disk damage usually did not change. This type of classification can probably be used accurately in clinical practice.

Female↗
PubMed2000

The effect of brimonidine tartrate on retinal blood flow in patients with ocular hypertension.

PURPOSE: To study the effects of topical brimonidine tartrate 0.2%, an alpha(2)-agonist ocular hypotensive drug, on retinal capillary blood flow in patients with ocular hypertension. METHODS: The study was a double-masked, randomized, placebo-controlled trial set in a tertiary eye center. Ocular hypertensive patients with repeatable intraocular pressures greater than 21 mm Hg and normal visual fields and optic disks were consecutively recruited. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry in one study eye. Patients were then randomly assigned to receive either brimonidine or placebo (saline) twice daily for 8 weeks. Blood flow and intraocular pressure measurements were then repeated after 4 and 8 weeks. RESULTS: Seventeen patients were randomly assigned to receive brimonidine, and 14 received placebo. One patient in each group failed to complete the study. The mean group differences in baseline age and intraocular pressure were not statistically significant (59. 23 [+/-10.24] and 52.23 [+/-16.46] years, respectively, and 24.84 [+/-2.08] and 24.56 [+/-2.85] mm Hg, respectively). Brimonidine reduced intraocular pressure by 17.90% and 16.17% at 4 and 8 weeks, respectively, with a significant difference in treatment effect compared with the placebo group (P <.007). The group difference in treatment effect in any of the three hemodynamic parameters velocity, volume, and flow was within 8% and not significantly different at 4 or 8 weeks (P.360). Based on a type I error of 0.05, our study had a power greater than or equal to 75% to detect group differences in treatment effect of greater than or equal to 15% to 20%. CONCLUSIONS: Brimonidine reduces intraocular pressure without altering retinal capillary blood flow in patients with ocular hypertension.

Adrenergic alpha-Agonists↗
PubMed2000

Intraocular pressure and progression of glaucomatous visual field loss.

PURPOSE: To evaluate the relationship between intraocular pressure and visual field progression in patients with primary open-angle glaucoma. METHODS: We prospectively followed 113 patients with early to moderate glaucomatous field damage. Conventional automated static perimetry, high-pass resolution perimetry, and intraocular pressure measurements were carried out at 6-month intervals. The mean and the highest intraocular pressure in the follow-up were compared in stable and progressing patients with each perimetric technique. RESULTS: The mean (+/- SD) follow-up was 4.5 +/- 0.9 years. The mean (+/- SD) intraocular pressure in patients remaining stable with conventional perimetry [18.2 +/- 3.3 mm Hg, n = 81 (71.7%)] was not significantly different (P =.65) from those in whom it progressed (17.9 +/- 3.3 mm Hg, n = 32 [28.3%]). The mean intraocular pressure in patients remaining stable with high-pass resolution perimetry (17. 9 +/- 3.5 mm Hg, n = 63 [55.8%]) was not significantly different (P =.33) from those in whom it progressed (18.5 +/- 3.0 mm Hg, n = 50 [44.2%]). The mean (+/- SD) of the highest (single or three highest) pressure during follow-up for stable and progressing patients with conventional perimetry was not significantly different (22.6 +/- 5.0 and 23.0 +/- 4.6 mm Hg, respectively, P =.76). However, for high-pass resolution perimetry, the difference was highly significant (21.6 +/- 4.5 and 24.1 +/- 4.9 mm Hg, respectively, P <. 01). Furthermore, patients who progressed with high-pass resolution perimetry had more damaged baseline fields compared with those who remained stable (P <.01). CONCLUSIONS: The mean level of intraocular pressure does not differentiate glaucoma patients with progressive visual field loss from ones who remained stable. Baseline visual field status and peak intraocular pressure of patients who progress with high-pass resolution perimetry are significantly different from those who remain stable.

Adolescent↗
PubMed2000

Technique for detecting serial topographic changes in the optic disc and peripapillary retina using scanning laser tomography.

PURPOSE: To describe and evaluate a new statistical technique for detecting topographic changes in the optic disc and peripapillary retina measured with confocal scanning laser tomography. METHODS: The 256x256-pixel array of topographic height values obtained with each image from the Heidelberg Retina Tomograph (Heidelberg Engineering, Heidelberg, Germany) was divided into an array of 64x64 superpixels, where each superpixel contained 16 (i.e., 4x4) pixels. An analysis of variance technique was developed to analyze each superpixel with three baseline and three follow-up images. The performance of the technique was tested with and without adjustment for spatial correlation of topographic values using computer simulations and with real data from a normal control subject and a patient with progressive glaucomatous disc change. RESULTS: Computer simulation with fixed population means and variance, and varying spatial correlation showed a monotonically increasing number of superpixels with significant test results (false positives), with 20% false-positives when the spatial correlation was 0.8 (the approximate median value in real patient data). The number of false-positive results was similar (17%) in serial images of a normal subject. When corrected for spatial correlation, the number of false-positives was independent of the level of spatial correlation and remained at the expected value of less than 5% in both simulations and real data. Although the number of significant test results in the patient with progressive glaucoma decreased after correction for spatial correlation, the change was readily apparent. Statistical power to detect mean differences in topographic values ranging from 0.5 to 4.0 SDs in computer simulation showed low power for changes of 1 SD or less, but increased dramatically with larger changes. CONCLUSIONS: This technique has a high level of sensitivity to detect changes in the optic disc while maintaining a high level of specificity.

Computer Simulation↗
PubMed2000

Comparison of conventional and pattern discrimination perimetry in a prospective study of glaucoma patients.

PURPOSE: To determine whether pattern discrimination perimetry detects progression of glaucomatous visual fields earlier than conventional static automated perimetry. METHODS: One hundred nine eyes of 109 patients with open angle glaucoma were enrolled in a longitudinal prospective study. Each patient underwent visual field examinations with conventional and pattern discrimination perimetry using the 30-2 program of the Humphrey Visual Field Analyzer (Humphrey Instruments Inc., San Leandro, CA) and a custom program for the pattern discrimination perimeter, respectively at 6-month intervals. Progression of glaucomatous visual field damage was assessed separately at each visit by predetermined criteria for conventional and pattern discrimination perimetry. The time to progression from baseline was calculated and the hemifield that showed progression first was documented for both conventional and pattern discrimination perimetry. RESULTS: Patients were followed for a mean of 5.1 years and a mean of 11.6 visits. Sixty-eight (62.3%) patients did not show progression with either technique. Of the remaining 41 patients, 15 (36.5%) showed progression with conventional perimetry alone, 9 (21.9%) with pattern discrimination perimetry alone, and 17 (41.4%) showed progression with both techniques. Of these 17 patients, 11 (64.7%) were detected earlier by conventional perimetry, and 6 (35.2%) were detected earlier by pattern discrimination perimetry. CONCLUSIONS: This study suggests that pattern discrimination perimetry is less effective than conventional perimetry in evaluating progressive glaucomatous visual field damage.

Adolescent↗
PubMed1999

Comparison of conventional and high-pass resolution perimetry in a prospective study of patients with glaucoma and healthy controls.

OBJECTIVE: To determine whether high-pass resolution perimetry detected glaucomatous visual field progression earlier than conventional perimetry. METHODS: In a prospective longitudinal study, we observed 113 patients with open-angle glaucoma and with early to moderate visual field damage and 119 healthy control subjects. Each subject underwent testing at 6-month intervals using conventional and high-pass resolution perimetry (program 30-2 of the Humphrey Field Analyzer [Humphrey Instruments, Inc, San Leandro, Calif] and the Ring program of the Ophthimus perimeter [Hi-Tech Vision, Göteborg, Sweden], respectively). Our predetermined criterion for progression with conventional perimetry was the presence of at least 4 overlapping nonedge locations outside the fifth percentile for test-retest variability of threshold deviations (defined by the Glaucoma Change Probability Analysis of the Statpac 2 program) in 2 of 3 consecutive visual fields. We employed the identical criterion for progression with high-pass resolution perimetry using our own test-retest variability data. We repeated this procedure in the controls to measure the false-positive rate of progression. RESULTS: Patients were observed for a median of 4.5 years and 11 examinations with each technique. Fifty-seven patients (50.4%) did not show progression with either technique. Twenty-four patients (21.2%) showed progression with high-pass resolution perimetry alone, whereas 6 (5.3%) showed progression with conventional perimetry alone. Of the remaining 26 patients (23.0%) who showed progression with both techniques, 14 (54%) showed progression with high-pass resolution perimetry first (median, 12 months earlier); 5 (19%), with conventional perimetry first (median, 6 months earlier); and 7 (27%), with both techniques at the same time. Controls were observed for a median of 5 years and 11 examinations with each technique. One control (0.8%) showed progression with high-pass resolution perimetry. CONCLUSIONS: Our results suggest that high-pass resolution perimetry detects glaucomatous visual field progression earlier than conventional perimetry in most patients with progression.

Adolescent↗
PubMed1998

Twelve-month results of an ongoing randomized trial comparing brimonidine tartrate 0.2% and timolol 0.5% given twice daily in patients with glaucoma or ocular hypertension. Brimonidine Study Group 2.

OBJECTIVE: To compare the long-term safety and ocular-hypotensive efficacy of brimonidine tartrate 0.2% with timolol maleate 0.5% administered twice daily in patients with glaucoma or ocular hypertension. DESIGN: A double-masked, parallel-group, active-controlled, multicenter clinical trial of 12 months' duration. PARTICIPANTS: Four hundred eighty-three patients with glaucoma or ocular hypertension were enrolled. Of these, 463 were evaluated according to the protocol criteria (280 in the brimonidine tartrate group and 183 in the timolol group). INTERVENTIONS: Brimonidine tartrate 0.2% or timolol maleate 0.5% was administered twice daily. MAIN OUTCOME MEASURES: The primary efficacy variable was intraocular pressure (IOP). RESULTS: Brimonidine and timolol produced significant (P < 0.001) and sustained mean reductions in IOP throughout the 1-year follow-up when measured at hour 0 (trough) and at hour 2 (peak). At weeks 1 and 2 and month 12, significantly greater mean decreases in IOP measured at peak (P < or = 0.007) were observed in patients treated with brimonidine as compared to timolol, whereas the mean decreases in IOP measured at trough was significantly greater in patients treated with timolol as compared to brimonidine (P < 0.001) at all follow-up visits. Both drugs were well-tolerated. The incidence of adverse events was similar in both treatment groups, except for ocular allergy, oral dryness, and conjunctival follicles, which occurred more frequently in the brimonidine group, and burning-stinging, which occurred more frequently in the timolol group. Patients receiving timolol experienced significant decreases in heart rate at all follow-up visits. CONCLUSIONS: Topically applied twice daily for 12 months, brimonidine tartrate 0.2% was safe and effective in lowering IOP in patients with glaucoma or ocular hypertension.

Adrenergic alpha-Agonists↗
PubMed1997

Repeatable diffuse visual field loss in open-angle glaucoma.

PURPOSE: The authors determined the frequency of repeatable diffuse loss as the only form of visual field damage in patients with early to moderate open-angle glaucoma in a prospective follow-up study. METHODS: The study contained 113 patients (median age, 64 years; range, 17-89 years) who were tested at 6-month intervals with program 30-2 of the Humphrey Field Analyzer (Humphrey Instruments Inc., San Leandro, CA). Although the inclusion criterion for visual acuity was > or = 20/40, on entry, 94 (83.2%) patients had an acuity of > or = 20/25. Cumulative defect curves were generated for all visual fields (median per patient, 7; range, 4-9). After randomizing the order and removing all patient information, two observers independently rated each visual field as being "normal" or showing "diffuse," "localized," or "diffuse and localized" loss. We defined repeatable diffuse loss as occurring when at least two thirds of the number of fields in the follow-up were classified as "diffuse." RESULTS: Fourteen patients (12.4%) had repeatable diffuse loss according to the cumulative defect curves. After reviewing their clinical charts, we excluded six of these patients because of early lens changes despite good visual acuity and three because of a suggestion of localized loss (on pattern deviation probability plots) in addition to the predominantly diffuse loss. The remaining five (4.4%) patients had repeatable diffuse loss that was due solely to open-angle glaucoma. CONCLUSION: Although diffuse visual field loss is exaggerated by factors other than glaucoma in the majority of patients, it can occur repeatedly in a small number of patients as the only sign of visual field damage.

Adolescent↗
PubMed1997

Intra- and interrater agreement with cumulative defect curves.

PURPOSE: To examine intra- and interrater agreement when analyzing cumulative defect curves. Cumulative defect (Bebié) curves provide a graphical representation of the visual field and allow a subjective classification of diffuse and localized loss. METHODS: We used 75 Humphrey 30-2 visual field tests, randomly chosen from a database of 782 fields of 113 patients with open-angle glaucoma. Cumulative defect curves were generated and randomly arranged into five sets, with each set containing the 75 curves in a unique sequence. Five raters (two experienced and three inexperienced) rated each set and classified each curve as showing diffuse loss, localized loss, both diffuse and localized loss, or no loss. The intra- and interrater agreement in rating the curves was then analyzed. RESULTS: Intrarater agreement ranged from 73.3-88.0% for perfect rater agreement, with 5 identical ratings. Agreement for experienced versus inexperienced raters gave similar results (means: 84.0% and 77.8%, respectively, for perfect agreement). Interrater agreement for each set, evaluated by the kappa statistic, was substantial for all 5 sets (0.65-0.71). Kappa values for each set were comparable for experienced and inexperienced raters (0.72-0.83 and 0.59-0.69 respectively). CONCLUSIONS: Analyzing the nature of visual field loss using the cumulative defect curve is simple to learn and provides high intrarater agreement as well as substantial interrater agreement.

Glaucoma, Open-Angle↗
PubMed1994

Technique for determining glaucomatous visual field progression by using animation graphics.

The first two visual field examinations of each of 16 glaucoma suspects and 16 glaucoma patients, who were followed up for a median of 7.46 years with seven examinations, were averaged. Three-dimensional color-coded images of the visual field were then generated. After correcting for test-retest variability, the images, as well as additional interpolated images, were aligned and presented in rapid succession to create an animation sequence. Five glaucoma specialists trained themselves to classify the visual fields as either progressing or not progressing. The interobserver and intraobserver agreement rates were then calculated. Perfect agreement (100% concordance) between the observers was obtained for 18 (56.3%) subjects, and at least 80% concordance was obtained for 27 (84.4%) subjects. Of the eight sequences that were repeated to test intraobserver agreement, four of the five observers had a value of at least 87.5%.

Adult↗
PubMed1994

Test-retest variability of topographic measurements with confocal scanning laser tomography in patients with glaucoma and control subjects.

Using confocal scanning laser tomography, we studied the test-retest variability of topographic measurements of the optic nerve head and parapapillary retina in 30 patients with glaucoma and 30 normal control subjects. We obtained three independent images, separated by between one and six hours, centered on the optic nerve head. We condensed each original 256 x 256-pixel image to a 64 x 64-pixel image, thereby allowing a realistic estimate of the empiric 90% confidence interval of testretest variability at each condensed pixel. Confidence interval maps generated for each subject showed highest measurement variability along the cup border and blood vessels. The mean standard deviation equivalents of test-retest variability in the patients and controls were 31.20 and 25.94 microns, respectively. These differences were statistically significant (P = .010). Variability increased with age (P < .001). When the analysis was repeated for discrete parapapillary areas, the group differences were not statistically significant (P = .100).

Adult↗
PubMed1994

Normal visual fields measured with Octopus-Program G1. II. Global visual field indices.

To complement results from individual test locations, clinicians also evaluate indices, as they give a succinct overview of the visual field. This, however, requires exact knowledge of their variability. The present study was designed to determine normal interindividual variability of global visual field indices and incorporates a data base of a multicenter study performed with Octopus 201 perimeters using Program G1. The 824 fields thus obtained included 139 fields of 139 healthy volunteers who had undergone two previous visual fields and completed all three phases of program G1. The index mean sensitivity showed a significant and linear decrease with increasing age, 0.064 dB/year of life. The indices loss variance, corrected loss variance, and short-term fluctuation did not correlate significantly with age. Percentiles are given for these visual field indices. While within the limits of normal values provided by the manufacturer for these indices, these results suggest that visual fields with "borderline" values require further clinical investigation in reliable, experienced subjects. The results may help clinicians to better evaluate global visual field indices and, therefore, to detect loss of visual function earlier.

Adult↗
PubMed1993

A double-masked comparison of betaxolol and dipivefrin for the treatment of increased intraocular pressure.

Noncardioselective beta-adrenoceptor antagonists are used for treatment of increased intraocular pressure. Because these agents may be absorbed systemically, their use is of concern in patients with restricted pulmonary function. We compared the efficacy of betaxolol, a cardioselective beta-adrenoceptor antagonist, and dipivefrin, an alpha/beta-adrenergic agonist. Seventy-six patients with open-angle glaucoma or ocular hypertension were randomly assigned to receive either betaxolol 0.5% or dipivefrin 0.1%. Patients were examined at two weeks, one month, two months, and three months. Intraocular pressure reductions were similar, with a mean decrease of 4.1 mm Hg in the betaxolol group and 3.5 mm Hg in the dipivefrin group. Both treatments caused similar minor increases in heart rate, typical with alpha-adrenergic agonists but atypical with beta-blockers. Stinging or burning in the betaxolol group was significantly (P = .008) greater than in the dipivefrin group. Our findings suggest that betaxolol and dipivefrin therapy are effective, equivalent ocular hypotensive agents.

Aged↗