Biomedical subjects

Felipe A Medeiros

Publications and source records attributed to Felipe A Medeiros.

At least 19 recordsLinked to original sources

PubMed2007

The effects of study design and spectrum bias on the evaluation of diagnostic accuracy of confocal scanning laser ophthalmoscopy in glaucoma.

PURPOSE: To assess the effects of study design and spectrum bias on the evaluation of diagnostic accuracy of confocal scanning laser ophthalmoscopy (CSLO) in glaucoma. METHODS: Analysis 1 included 67 eyes with glaucomatous visual field loss and 56 eyes of normal volunteers. Estimates of diagnostic accuracy in this analysis were compared to those obtained from analysis 2, which included a cohort of patients with suspected glaucoma, but without visual field loss at the time of CSLO imaging. For analysis 2, 40 eyes with progressive glaucomatous optic disc change were included in the glaucoma group and 43 eyes without any evidence of progressive damage to the optic nerve that were observed untreated for an average time of 9.01 +/- 3.09 years were included in the normal group. Areas under the receiver operating characteristic (ROC) curves (AUC) were used to evaluate diagnostic accuracy of CSLO parameters. RESULTS: There was a statistically significant difference between the performance of the parameter with largest AUC, discriminant function Bathija, in analysis 1 (AUC = 0.91) compared with its performance in analysis 2 (AUC = 0.71; P = 0.002). For the contour-line-independent parameter glaucoma probability score, a statistically significant difference was also observed in the performance obtained in analysis 1 (AUC = 0.89) compared with analysis 2 (AUC = 0.65; P < 0.001). CONCLUSIONS: Estimates of diagnostic accuracy of CSLO in glaucoma can be largely different depending on the population studied and the reference standard used to define disease. Diagnostic accuracy estimates obtained from case-control studies including well-defined groups of subjects with or without disease may not be applicable to the clinically relevant population.

Adult↗

PubMed2007

The effect of atypical birefringence patterns on glaucoma detection using scanning laser polarimetry with variable corneal compensation.

PURPOSE: The purpose of this study was to investigate the effect of the presence of atypical birefringence patterns, as measured by the typical scan score (TSS), on the diagnostic accuracy of a scanning laser polarimeter (the GDx VCC; Carl Zeiss Meditec, Inc., Dublin, CA) assessed by receiver operating characteristic (ROC) curves for discriminating between glaucoma and healthy eyes. METHODS: Two hundred thirty-three glaucomatous eyes (repeatable abnormal visual fields by pattern standard deviation [PSD] and/or glaucoma hemifield test [GHT]) from 153 patients with glaucoma and 104 eyes from 71 healthy participants enrolled in the UCSD Diagnostic Innovations in Glaucoma Study (DIGS) were imaged using the GDx VCC. An ROC regression model was used to evaluate the influence of the covariates TSS; disease severity, defined as standard automated perimetry (SAP) mean deviation [MD]; and age in years on the diagnostic accuracy of the GDx parameters nerve fiber indicator [NFI], TSNIT (temporal, superior, nasal, inferior, temporal) average thickness, superior average thickness, inferior average thickness, and TSNIT standard deviation. Areas under the ROC curve were calculated for specific levels of the covariates according to the results provided by the model. RESULTS: TSS and SAP MD significantly affected the diagnostic accuracy of each investigated GDx VCC parameter. Low TSSs, indicating the presence of atypical scans, were associated with decreased accuracy. For NFI, ROC curve areas ranged from 0.749 (when TSS = 20) to 0.904 (when TSS = 100). A similar influence of TSS was found for other parameters. In addition, diagnostic accuracy increased with increasing disease severity. For instance, for NFI, ROC curve areas ranged from 0.853 (when SAP MD = -3) to 0.954 (when SAP MD = -15). CONCLUSIONS: The diagnostic accuracy of GDx VCC parameters is affected by disease severity and is adversely affected by the presence of atypical retardation patterns (i.e., decreasing TSS). GDx VCC scans with atypical scan patterns should be interpreted with caution when used in clinical practice.

Adolescent↗

PubMed2006

Comparison of dynamic contour tonometry and goldmann applanation tonometry in African American subjects.

PURPOSE: To evaluate the relationship between intraocular pressure (IOP) measurements obtained by dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in African Americans and to assess whether these measures were influenced by ocular parameters including corneal thickness, corneal curvature, and axial length. DESIGN: Observational clinical study. PARTICIPANTS: The study included 176 eyes of 94 African Americans. METHODS: All participants underwent IOP evaluation with DCT and GAT, as well as measurements of central corneal thickness (CCT), corneal curvature, corneal astigmatism, spherical equivalent, and axial length. MAIN OUTCOME MEASURES: Univariate and multiple regression analyses were used to evaluate the associations between IOP (as measured with DCT and GAT) and CCT, corneal curvature, corneal astigmatism, spherical equivalent, axial length, and age. Bland-Altman plots were used to evaluate the agreement between IOP measurements obtained by DCT and GAT. RESULTS: In multiple regression analysis, GAT IOP measurements were significantly associated with CCT (P<0.001) and age (P = 0.003), whereas DCT IOP measurements were associated only with age (P = 0.027). The difference between DCT and GAT IOP measurements was significantly influenced by corneal thickness (P<0.001) and ocular pulse amplitude (OPA; P = 0.004). Patients with thick corneas tended to have higher GAT IOP measurements compared with DCT, whereas in patients with thin corneas, GAT IOP measurements tended to be lower than DCT measurements. Larger values of OPA were associated with a decrease in the difference between DCT and GAT measurements, whereas smaller values of OPA were associated with an increase in the difference between DCT and GAT measurements. CONCLUSIONS: Dynamic contour tonometry measurements in African Americans seem to provide an estimate of IOP that is less influenced by corneal properties than those provided by GAT.

Adult↗

PubMed2006

Evaluation of macular thickness measurements for detection of band atrophy of the optic nerve using optical coherence tomography.

PURPOSE: To evaluate the ability of optical coherence tomography (OCT) macular thickness parameters to differentiate between eyes with band atrophy (BA) of the optic nerve and healthy eyes. DESIGN: Cross-sectional study. PARTICIPANTS: The study included 1 eye of each of 40 consecutive patients with BA of the optic nerve and permanent temporal hemianopic visual field (VF) defects owing to chiasmal compression and 31 age- and gender-matched healthy subjects. METHODS: All patients underwent VF assessment with kinetic Goldmann perimetry and Humphrey 24-2 full-threshold standard automated perimetry (SAP). Macular and retinal nerve fiber layer (RNFL) thickness scans were obtained using the commercially available Stratus OCT. The severity of VF defect in patients with BA was evaluated by the temporal mean defect (TMD), calculated as the average of the 22 values of the temporal total deviation plot of the SAP 24-2 test, excluding the 2 points immediately above and below the blind spot. MAIN OUTCOME MEASURES: Receiver operating characteristic (ROC) curves and sensitivities at fixed specificities were calculated for each parameter. Spearman's rank correlation coefficients were used to evaluate the relationship between RNFL and macular thickness parameters and severity of VF loss as measured by the TMD. RESULTS: The macular thickness parameters related to the nasal hemiretina had the best performance to detect damage in BA eyes. No statistically significant difference (P = 0.19) was found between the ROC curve areas (AUCs) for the best macular thickness parameter (temporal/nasal macular thickness, AUC = 0.96) and the best RNFL parameter (average thickness, AUC = 0.99). Lower values of TMD, indicating more severe VF loss, were associated with lower macular thickness measurements. The highest correlation was observed for the parameter nasal average macular thickness (rho = 0.693, R2 = 48%, P<0.001). CONCLUSION: Eyes with BA of the optic nerve show significant thinning of the retinal thickness on the nasal macular area, which is associated with the severity of VF damage in these eyes. Macular thickness measurements could potentially be used to evaluate the amount of ganglion cell loss in patients with BA of the optic nerve and could prove clinically useful for detection of damage and for monitoring these patients.

Adolescent↗

PubMed2006

Intereye concordance in locations of visual field defects in primary open-angle glaucoma: diagnostic innovations in glaucoma study.

PURPOSE: To determine the overlap in defective visual field locations between the right and left eyes of primary open-angle glaucoma patients. DESIGN: Cross-sectional retrospective analysis of data from a prospectively designed longitudinal study. PARTICIPANTS: Patients with glaucomatous optic neuropathy in at least 1 eye and 2 consecutive reliable standard automated perimetry fields within 15 months were included, yielding 468 eyes of 234 patients. METHODS: Concordance in defective visual field locations between right and left eyes were calculated as the number of overlapping locations divided by the total number of defective locations (intereye concordance ratio). Concordance ratios also were calculated within an eye over time (intraeye concordance ratio) and between unmatched pairs of fields (unmatched concordance ratio). RESULTS: Intereye concordance (0.24+/-0.02) was significantly smaller than intraeye concordance (0.37+/-0.02) and significantly larger than unmatched concordance (0.14+/-0.01). There was a significant interaction between concordance type and defect size, such that there was no difference in concordance ratios for defects of fewer than 8 locations, and the difference between intereye concordance versus intraeye concordance and unmatched concordance ratios increased with larger defect sizes. CONCLUSIONS: A spatial relationship exists between defective locations of an individual's eyes. Future studies will show whether information about the spatial relationship is useful to guide the modification of visual field test locations to improve detection of loss and perhaps also progression.

Adult↗

PubMed2006

Relationship between patterns of visual field loss and retinal nerve fiber layer thickness measurements.

PURPOSE: To investigate the association between patterns of visual field (VF) loss and retinal nerve fiber layer (RNFL) thickness measurements. DESIGN: Observational cross-sectional study. METHODS: One hundred twenty-one glaucoma patients and 65 healthy subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were included. All glaucoma patients had repeatable abnormal VFs and scanning laser polarimetry (SLP) RNFL thickness measurements. RNFL measurements were obtained from 16 equal parapapillary sectors. Patterns of VF loss were classified as arcuate, partial arcuate, nasal step, or paracentral in each VF hemifield. Logistic regression analysis was performed to determine which RNFL sectors were associated with each VF pattern. The ability of SLP to discriminate between eyes with different VF patterns and healthy eyes using receiver operating characteristic (ROC) curve analyses also was investigated. RESULTS: VF patterns in the superior hemifield were significantly associated with RNFL sectors in the temporal inferior hemiretina (P < .05). ROC curve areas for discrimination between eyes with different VF patterns and healthy eyes ranged from 0.85 to 0.95. VF patterns in the inferior hemifield were most strongly associated with temporal superior RNFL sectors (P < .05). ROC curve areas for discrimination between different VF patterns and healthy eyes ranged from 0.73 to 0.98. SLP could discriminate between apparently unaffected VF hemifields in glaucoma eyes and VF hemifields in healthy eyes. CONCLUSIONS: Parapapillary RNFL thickness was topographically related to patterns of VF loss. SLP can differentiate between apparently unaffected VF hemifields in glaucoma eyes and normal VF hemifields in healthy eyes.

Aged↗

PubMed2006

Baseline optical coherence tomography predicts the development of glaucomatous change in glaucoma suspects.

PURPOSE: To assess whether baseline retinal nerve fiber layer (RNFL) measurements obtained with optical coherence tomography (OCT2; Carl Zeiss Meditec, Dublin, California, USA) are predictive of the development of glaucomatous change. DESIGN: Cohort study. METHODS: Participants were recruited from the University of California, San Diego (UCSD) longitudinal Diagnostic Innovations in Glaucoma Study (DIGS). One eye was studied from each of 114 glaucoma suspects with normal standard automated perimetry (SAP) and OCT RNFL imaging at baseline. The cohort was divided into two groups based on the development of glaucomatous change (repeatable abnormal visual fields and/or a change in the stereophotographic appearance of the optic disk). Cox proportional hazards models were used to determine the predictive ability of OCT RNFL thickness measurements. RESULTS: Over a 4.2-year average follow-up period, 23 eyes (20%) developed glaucomatous changes and 91 (80%) did not. At baseline, thinner RNFL measurements, higher SAP pattern standard deviation (PSD), "glaucoma" stereophotograph assessment, and thinner central corneal thickness (CCT) were associated with the study endpoints in univariate analysis. After adjusting for age, intraocular pressure (IOP), CCT, and PSD in multivariate models, a 10 mum thinner average, superior and inferior RNFL at baseline was predictive of glaucomatous change [hazard ratio (95% CI); 1.51 (1.11 to 2.12), 1.57 (1.17 to 2.18), and 1.49, (1.19 to 1.91), respectively]. Results were consistent when stereophotographic assessment was included in multivariate analysis. CONCLUSIONS: Thinner OCT RNFL measurements at baseline were associated with development of glaucomatous change in glaucoma suspect eyes. RNFL thinning was an independent predictor of the glaucomatous change, even when adjusting for stereophotograph assessment, age, IOP, CCT, and PSD.

Cohort Studies↗

PubMed2006

Combining structural and functional testing for detection of glaucoma.

PURPOSE: To assess whether the combined use of both structural and functional tests improves discrimination between healthy and glaucomatous eyes over either type of testing alone. DESIGN: Observational cross-sectional study. PARTICIPANTS: One hundred twenty-three eyes of 123 participants enrolled in the Diagnostic Innovations in Glaucoma Study. METHODS: Because both structural and functional tests were evaluated, 2 definitions of glaucoma were used: glaucomatous visual field (VF) damage based on repeatable abnormal standard automated perimetry results (n = 43) and glaucomatous optic disc (glaucomatous optic neuropathy [GON]) based on masked assessment of optic disc stereophotographs (n = 65). Participants had scanning laser polarimetry, optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy imaging in addition to frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) testing completed within a 6-month interval. MAIN OUTCOME MEASURES: For each glaucoma definition, sensitivities and specificities were calculated for the best structural parameters, FDT perimetry pattern standard deviation (PSD), and SWAP PSD/glaucoma hemifield test, and then for each possible pairwise combination of one structural and one functional parameter. RESULTS: The best structural parameters for discriminating between glaucoma and control eyes were nerve fiber indicator for scanning laser polarimetry, inferior average retinal nerve fiber layer thickness for OCT, and Moorfields regression classification for confocal scanning laser ophthalmoscopy. Sensitivities and specificities for detecting glaucomatous VF damage for scanning laser polarimetry, OCT, confocal scanning laser ophthalmoscopy, FDT perimetry, and SWAP were 41.9% and 98.3%, 58.1% and 98.3%, 58.1% and 84.5%, 44.2% and 98.3%, and 65.1% and 86.2%, respectively. Adding FDT perimetry to each of the best structural parameters led to a significant (P<0.05) increase in sensitivity without a significant change in specificity compared with structural parameters alone. Adding SWAP to each of the best structural parameters led to a significant increase in sensitivity and also a significant decrease in specificity compared with each structural parameter alone. CONCLUSIONS: A combination of parameters from structural tests and functional tests can improve the sensitivity of glaucoma detection. The sensitivity and specificity desired for a particular clinical application will determine the selection of the particular diagnostic tests.

Aged↗

PubMed2006

Evaluation of the influence of corneal biomechanical properties on intraocular pressure measurements using the ocular response analyzer.

PURPOSE: The Ocular Response Analyzer (ORA) proposes to measure corneal biomechanical properties in vivo by monitoring and analyzing the corneal behavior when this structure is submitted to a force induced by an air jet. The purpose of this study was to evaluate the relationship between corneal biomechanical properties and corneal-compensated intraocular pressure (IOPCC) measurements as obtained by the ORA and Goldmann applanation tonometry (GAT) measurements. DESIGN: Observational clinical study. METHODS: The study included 153 eyes of 78 subjects. All subjects underwent IOP evaluation with the ORA and GAT, and also measurements of central corneal thickness (CCT), corneal curvature, and axial length. Univariable and multivariable regression analysis were used to evaluate the associations between IOP (as measured with GAT and ORA) and CCT, corneal curvature, axial length, and age. Bland and Altman plots were used to evaluate the agreement between IOP measurements obtained by GAT and ORA. RESULTS: GAT IOP measurements were significantly associated with CCT (P=0.001) and corneal curvature (P<0.001), whereas ORA IOPCC measurements were not associated with any of the ocular variables. The difference between GAT and IOPCC measurements was significantly influenced by corneal thickness. Patients with thicker corneas tended to have higher GAT IOP measurements compared with IOPCC, whereas in patients with thin corneas, GAT IOP measurements tended to be lower than IOPCC. CONCLUSIONS: ORA IOPCC measurements seem to provide an estimate of IOP that is less influenced by corneal properties than those provided by GAT.

Adult↗

PubMed2006

Inconsistency of the published definition of ocular hypertension.

PURPOSE: To examine the variability and to evaluate the influence of the Ocular Hypertension Treatment Study (OHTS) on the criteria for published definition of ocular hypertension (OH). DESIGN: Systematic literature review. METHODS: All articles about OH published between January 1995 and July 2005 from the 3 clinical journals of ophthalmology were identified by a literature search. They were reviewed to determine the criteria used to define OH, including intraocular pressure and central corneal thickness, visual field and optic disc assessment. RESULTS: There were 133 studies published on OH during the period under study. As a goal of the current study was to evaluate the influence of the publication of the OHTS results on the definition of OH used in the literature, all reports from the OHTS and its ancillary studies (n = 11) were excluded from the main analysis. After the exclusion of the OHTS reports, a total of 122 studies were used in the analysis. The intraocular pressure cut-off level used for OH diagnosis ranged from 18 to 26 mm Hg, with a mode of 22 mm Hg (49.2%). Only 13.1% of the articles reported central corneal thickness, and these were distributed evenly during the 10-year period under study. Visual field assessment was reported by most of the studies (110; 90.2%), but only 45% of them defined the criteria to classify a field as normal or glaucomatous. Further, only 37 of the 57 articles that reported the method of optic disc assessment described the criteria used to classify optic discs. CONCLUSIONS: The criteria used to define OH during the past 10 years have been highly variable. This wide variation suggests the important need for a standardized definition of OH.

Humans↗

PubMed2006

Retinal nerve fibre layer thickness measurements in patients using chloroquine.

PURPOSE: Previous investigations have suggested that initial retinal damage from chloroquine toxicity occurs in ganglion cells, and other ocular tissues are affected only later on. The aim of this study was to evaluate retinal nerve fibre layer (RNFL) thickness measurements, as assessed by scanning laser polarimetry, in a group of patients under long-term treatment with chloroquine. METHODS: This case-control study included 34 patients using chloroquine diphosphate and 34 age-matched healthy subjects with no previous history of chloroquine intake. All subjects underwent RNFL assessment using the GDx -- Nerve Fibre Analyser (software v.2.0.01). One eye of each patient was randomly selected for statistical analysis. Peripapillary RNFL measurements were compared between the two groups. For patients using chloroquine, the correlation between RNFL measurements and chloroquine dosage was assessed. RESULTS: Mean +/- SD RNFL thickness for patients using chloroquine was 60.6 +/- 11.2 microm, 65.6 +/- 13.2 microm, 74.8 +/- 14.8 microm, 36.2 +/- 9.6 microm and 43.8 +/- 7.9 microm for global, superior, inferior, temporal and nasal regions, respectively. In the control group, the corresponding values were 72.1 +/- 12.7 microm, 79.9 +/- 14.8 microm, 88.3 +/- 14.0 microm, 44.2 +/- 12.8 microm and 49.7 +/- 11.9 microm. Mean RNFL thickness measurements from patients using chloroquine were significantly different from those in the control group in all regions (P < 0.05). Thinner RNFL thickness measurements were associated with higher daily dosages of chloroquine. CONCLUSION: Patients under long-term chloroquine treatment had significantly lower RNFL thickness measurements than healthy subjects, and the RNFL loss was correlated to chloroquine daily dosage.

Adult↗

PubMed2006

Influence of disease severity and optic disc size on the diagnostic performance of imaging instruments in glaucoma.

PURPOSE: To evaluate the influence of disease severity and optic disc size on the diagnostic accuracy of three imaging technologies for structural assessment in glaucoma: confocal scanning laser ophthalmoscopy, scanning laser polarimetry, and optical coherence tomography. METHODS: One hundred five patients with glaucoma and 61 normal subjects were recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). All individuals underwent imaging with the GDx Variable Corneal and Lens Compensator (VCC; Carl Zeiss Meditec, Inc., Dublin, CA), the Heidelberg Retina Tomograph II (HRT II; Heidelberg Engineering, GmbH, Dossenheim, Germany), and the Stratus OCT (Stratus OCT; Carl-Zeiss Meditec, Inc.) within a 6-month period. Severity of disease was based on the AGIS (Advanced Glaucoma Intervention Study) visual field score. To evaluate the influence of severity of glaucoma and optic disc size on the diagnostic accuracy of the imaging instruments, the sensitivities of the tests were fitted as a function of the AGIS score and disc area, by using logistic marginal regression models. RESULTS: The severity of visual field loss had a significant influence on the sensitivity of all imaging instruments. More severe disease was associated with increased sensitivity. This influence was similar among the three instruments. With regard to optic disc area, larger optic discs were associated with decreased sensitivity for the Stratus OCT parameter Average Thickness and the GDx VCC parameter Nerve Fiber Indicator, whereas small optic discs were associated with increased sensitivity. For the HRT II parameter Moorfields regression analysis classification, an inverse effect was observed. CONCLUSION: The diagnostic performances of the GDx VCC, HRT II, and Stratus OCT were significantly influenced by the severity of the disease and optic disc size. These covariates should be taken into account when comparing the performances of these tests for glaucoma diagnosis.

Aged↗

PubMed2006

A statistical approach to the evaluation of covariate effects on the receiver operating characteristic curves of diagnostic tests in glaucoma.

PURPOSE: To describe an approach for the evaluation of covariate effects on receiver operating characteristic (ROC) curves and to apply this methodology to the investigation of the effects of disease severity and age on the diagnostic performance of frequency doubling technology (FDT) and standard automated perimetry (SAP) visual function tests for glaucoma detection. METHODS: The study included 370 eyes of 211 participants, with 174 eyes of 110 patients having glaucomatous optic neuropathy and 196 eyes of 101 subjects being normal. All patients underwent visual function testing with FDT 24-2 Humphrey Matrix and SAP SITA (Carl Zeiss Meditec, Inc., Dublin, CA). Disease severity was evaluated by the amount of neuroretinal rim loss assessed by confocal scanning laser ophthalmoscopy. An ROC regression model was fitted to evaluate the influence of disease severity and age on the diagnostic performance of the pattern SD (PSD) index from FDT 24-2 and SAP SITA. RESULTS: After adjustment for age, the areas under the ROC curves (AUCs) for SAP SITA PSD for 10%, 30%, 50%, and 70% loss of neuroretinal rim area were 0.638, 0.756, 0.852, and 0.920, respectively. Corresponding values for FDT 24-2 PSD were 0.766, 0.857, 0.922, and 0.962. For 10% and 30% rim loss, FDT 24-2 PSD had a significantly larger AUC than did SAP SITA PSD. CONCLUSIONS: A regression methodology to evaluate covariate effects on ROC curves can be useful for assessment of diagnostic tests in glaucoma. Using the proposed methodology, a significantly better performance of FDT 24-2 compared to SAP SITA for diagnosis of early glaucoma was demonstrated.

Age Factors↗

PubMed2006

Structure-function relationships using confocal scanning laser ophthalmoscopy, optical coherence tomography, and scanning laser polarimetry.

PURPOSE: To assess the strength of the association between retinal nerve fiber layer (RNFL) thickness and optic disc topography measured with confocal retinal tomography (HRT II; Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography (StratusOCT; Carl Zeiss Meditec, Inc., Dublin, CA), and scanning laser polarimetry (GDx with variable corneal compensator, VCC; Carl Zeiss Meditec, Inc.), and visual field (VF) sensitivity and to determine whether this association is better expressed as a linear or nonlinear function. METHODS: One hundred twenty-seven patients with glaucoma or suspected glaucoma and 127 healthy eyes from enrollees in the Diagnostic Innovations in Glaucoma Study (DIGS) were tested on HRT II, StratusOCT, GDx VCC, and standard automated perimetry (SAP, with the Swedish Interactive Thresholding Algorithm [SITA]) within 3 months of each other. Linear and logarithmic associations between RNFL thickness (HRT II, StratusOCT, and GDx VCC) and neuroretinal rim area (HRT II) and SAP sensitivity expressed in decibels were determined globally and for six RNFL/optic disc regions (inferonasal, inferotemporal, temporal, superotemporal, superonasal, and nasal) and six corresponding VF regions (superior, superonasal, nasal, inferonasal, inferior, and temporal). RESULTS: The associations (R2) between global and regional RNFL/optic disc measurements and VF sensitivity ranged from <0.01 (temporal RNFL, nasal VF, and nasal RNFL, temporal VF; linear and logarithmic associations) to 0.26 (inferotemporal RNFL, superonasal VF; logarithmic association) for HRT II; from 0.02 (temporal RNFL, nasal VF; linear association) to 0.38 (inferotemporal RNFL, superonasal VF; logarithmic association) for OCT; and from 0.03 (temporal RNFL, nasal VF; linear association) to 0.21 (inferotemporal RNFL, superonasal VF; logarithmic association) for GDx. Structure-function relationships generally were strongest between the inferotemporal RNFL-optic disc sector and the superonasal visual field and were significantly stronger for StratusOCT RNFL thickness than for other instruments in this region. Global associations (linear and logarithmic) were significantly stronger using OCT compared with HRT. In most cases, logarithmic fits were not significantly better than linear fits when visual sensitivity was expressed in log units (i.e., decibels). CONCLUSIONS: These results suggest that structure-function associations are strongest with StratusOCT measurements and are similar between HRT II and GDx VCC and these associations are generally no better expressed logarithmically than linearly when healthy, suspect, and glaucomatous eyes are considered.

Female↗

PubMed2006

Identifying glaucomatous vision loss with visual-function-specific perimetry in the diagnostic innovations in glaucoma study.

PURPOSE: To compare the diagnostic results of four perimetric tests and to identify useful parameters from each for determining abnormality. METHODS: One hundred eleven eyes with glaucomatous optic neuropathy (GON), 31 with progressive optic neuropathy (PGON) 53 with ocular hypertension, and 51 with no disease were included (N = 246). Visual field results were not used to classify the eyes. Short-wavelength automated perimetry (SWAP), frequency-doubling technology perimetry (FDT), high-pass resolution perimetry (HPRP), and standard automated perimetry (SAP) were performed. Receiver operating characteristic (ROC) curves were used to compute the areas under the curves (AUC) and sensitivity levels at given specificities for a variety of abnormality criteria. The agreement among tests for abnormality, location, and extent of visual field deficit were assessed. RESULTS: AUC analysis: When the normal group was compared with the GON group, the FDT pattern SD (PSD) area was larger than the HPRP PSD (P = 0.020), and the FDT area of total deviation (TD) <5% was larger than the HPRP mean deviation (MD; P = 0.004). When the normal group was compared with the PGON group, the FDT area of pattern deviation (PD) <5% was larger than the SWAP PSD (P = 0.020). A difference from previous work was that AUCs for PSD or the best SAP were not significantly poorer than those in the function-specific tests. At set specificities, FDT yielded higher sensitivities than all other tests for all parameters. The agreement among tests for abnormality was fair to moderate (kappa = 247-0.563). When loss was present on more than one test, the quadrant of the visual field affected was the same in 95% (79/83) of eyes. The number of eyes identified and number of abnormal quadrants increased across groups with increasing certainty of glaucoma. CONCLUSIONS: At equal specificity, no single perimetric test was always affected, whereas others remained normal. Several parameters at suggested criterion values provided good sensitivity and specificity. FDT showed the highest sensitivity overall, with SAP performing better than in prior reports. Of note, the same area of the retina was identified as damaged in all tests.

Adult↗

PubMed2005

Agreement among 3 optical imaging methods for the assessment of optic disc topography.

PURPOSE: To assess the agreement of disc topography measurements between the Heidelberg Retina Tomograph (HRT II), Retinal Thickness Analyzer (RTA), and Optical Coherence Tomograph (StratusOCT). DESIGN: Observational cross-sectional study. PARTICIPANTS: Forty-two randomly chosen eyes of 42 subjects. METHODS: Each subject underwent HRT II, RTA, and StratusOCT examination. Two experienced examiners drew the contour lines for the HRT II and RTA. Bland and Altman plots were used to evaluate agreement for each topographic parameter among the instruments. The Spearman coefficient of rank correlation was evaluated for each topographic parameter. MAIN OUTCOME MEASURES: Agreement in the measurement of optic disc topography among 3 imaging instruments, as evaluated by regression-based 95% limits of agreement. RESULTS: For optic disc area, the agreement between HRT II-RTA and StratusOCT-RTA revealed the existence of proportional bias, indicated by significant slopes of the regression lines (P = 0.01 and P = 0.02, respectively). The 95% limits of agreement between instruments varied with the actual optic disc size measurement. Heidelberg Retina Tomograph disc area measurements tended to be consistently lower than StratusOCT disc area measurements (fixed bias). The Spearman correlation coefficient between the instruments ranged from r = 0.35 (rim area, HRT II-StratusOCT) to r = 0.91 (cup area, HRT II-RTA). CONCLUSIONS: Moderate to high correlation was found in measurements of optic disc topography among different instruments. However, the analysis of agreement indicated important discrepancies among instruments. Therefore, these instruments should not be used interchangeably to obtain measurements of the optic disc for glaucoma diagnosis.

Aged↗

PubMed2005

Repeatability and reproducibility of optic nerve head topography using the retinal thickness analyzer.

OBJECTIVE: The objective was to determine the reproducibility and repeatability of topographic disk parameters with the retinal thickness analyzer (RTA). METHODS: Thirty-nine eyes of 39 healthy subjects were included. Three observers performed three consecutive measurements of optic disk topography independently. Combined repeatability (intra-observer component of variability) and reproducibility (inter-observer component of variability, R and R) was assessed by variance component analysis. RESULTS: Six topographic parameters (disk area, cup area, cup volume, mean cup depth, maximum depth, and cup shape measure) revealed an acceptable repeatability and reproducibility expressed as the percentage of the total measurement variability (range 17.6-28.4%). The average reproducibility and repeatability of all optic disk parameters measured using the RTA was not acceptable (combined R and R = 33.4%). CONCLUSIONS: Repeatability and reproducibility of the optic disk topography analysis using the RTA reveals a high variation, and should, therefore, be interpreted carefully for glaucoma diagnosis and for monitoring the disease.

Adult↗

PubMed2005

Validation of a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma.

OBJECTIVES: To develop and validate a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma. METHODS: Predictive models for the 5-year risk of conversion to glaucoma were derived from the results of the Ocular Hypertension Treatment Study (OHTS). The performance of these models was assessed in an independent population of 126 subjects with ocular hypertension from a longitudinal study (Diagnostic Innovations in Glaucoma Study [DIGS]). The performance of the OHTS-derived models was assessed in the DIGS cohort according to equality of regression coefficients, discrimination (c-index), and calibration. RESULTS: Thirty-one patients (25%) developed glaucoma during follow-up. Hazard ratios for DIGS- and OHTS-derived predictive models were similar for age, intraocular pressure, central corneal thickness, vertical cup-disc ratio, and pattern standard deviation but were significantly different for the presence of diabetes mellitus. When applied to the DIGS population, the OHTS-derived predictive models had reasonably good discrimination (c-indexes of 0.68 [full model] and 0.73 [reduced model]) and calibration. CONCLUSIONS: The OHTS-derived predictive models performed well in assessing the risk of glaucoma development in an independent population of untreated subjects with ocular hypertension. A risk scoring system was developed that allows calculation of the 5-year risk of glaucoma development for an individual patient.

Disease Progression↗