Faculty Bibliography

PURPOSE: To compare computer-assisted planimetry using the Discam system (Marcher Enterprises Ltd., Hereford, UK), confocal scanning laser ophthalmoscopy (CSLO), and stereoscopic disc photography with respect to optic nerve head (ONH) measurements and glaucoma status. DESIGN: Comparative, observational case series and interobserver variability study. METHODS: Three hundred eighty-six eyes of 233 consecutive subjects were imaged with the Discam, and a subset underwent ONH evaluation with CSLO (n = 297), stereoscopic photography (n = 233), or both. Subjects were classified into normal, glaucoma suspect, and glaucoma groups based on clinical findings of slit-lamp disc examination and visual field testing. Agreement of cup-to-disc ratio measurements among the three technologies was assessed by the intraclass correlation coefficient (ICC) and areas under the receiver operator characteristic (AROC) curves. MAIN OUTCOME MEASURES: Cup-to-disc ratio as measured by Discam, CSLO, and stereography. RESULTS: Intraclass correlation coefficients calculated using the two-way random effects model for comparing Discam, CSLO, and stereography among cup-to-disc area ratio, vertical cup-to-disc ratio, and horizontal cup-to-disc ratio were 0.46 to 0.53. The ICC was higher for eyes with larger optic discs (0.51) than those with smaller ones (0.32). The ICC calculated using the fixed effects model for the Discam and CSLO comparison was 0.72. Areas under the receiver operator characteristic curves were 0.67 to 0.80 among the three technologies comparing normal with glaucomatous eyes. In general, there was no statistically significant difference between techniques with respect to sensitivity and specificity of glaucoma detection. CONCLUSIONS: There is good agreement between ONH measurements obtained by Discam, CSLO, and stereography; however, the results are not interchangeable. Similar AROC curve values among all three techniques imply that the Discam, CSLO, and stereography perform equally for the determination of glaucoma status.

PURPOSE: To evaluate the relationship between optic nerve head (ONH) measurements generated by optical coherence tomography (OCT; versions 2 and 3) and confocal scanning laser ophthalmoscopy (CSLO) and to compare the association between OCT and CSLO ONH measurements with glaucoma disease status, as determined by clinical evaluation and perimetry. DESIGN: Cross-sectional study. METHODS: In a prospective study in the glaucoma service of an academic department of ophthalmology, 159 eyes (97 subjects) and 77 eyes (44 subjects) were recruited in two separate periods. All subjects were scanned with a CSLO device. Subjects tested within the first period of recruitment were scanned with OCT version 2 and in the second period with OCT version 3. The main outcome measure was the correlation between automatic and manually defined OCT ONH measurements and the correlation of CSLO and OCT ONH measurements between devices and with glaucoma disease status. RESULTS: A high correlation was found between ONH measurements obtained by the automatic determination of ONH margin and those obtained by manual tracing of the disk margin (r =.93 to.98). Optical coherence tomography and CSLO ONH measurements were highly correlated. Optical coherence tomography-measured mean disk area was significantly larger than that measured by CSLO, as were all other disk size-related parameters. The areas under the receiver operator characteristic (AROC) curves for the associations between CSLO and OCT ONH measurements and clinical diagnosis were found to be similar and in the range of 0.47 to 0.79 for both devices. CONCLUSIONS: Automated OCT ONH measurements correlate highly with those obtained by manual tracing of disk margin. Optical coherence tomography and CSLO ONH analyses are highly correlated and have similar associations with glaucoma disease status.

PURPOSE: To evaluate the hypothesis that macular thickness correlates with the diagnosis of glaucoma. DESIGN: Cross-sectional study. PARTICIPANTS: We studied 367 subjects (534 eyes), including 166 eyes of 109 normal subjects, 83 eyes of 58 glaucoma suspects, 196 eyes of 132 early glaucoma patients, and 89 eyes of 68 advanced glaucoma patients. METHODS: We used optical coherence tomography (OCT) to measure macular and nerve fiber layer (NFL) thickness and to analyze their correlation with each other and with glaucoma status. We used both the commercial and prototype OCT units and evaluated correspondence between measurements performed on the same eyes on the same days. MAIN OUTCOME MEASURE: Macular and NFL thickness as measured by OCT. RESULTS: All NFL parameters both in prototype and commercial OCT units were statistically significantly different comparing normal subjects and either early or advanced glaucoma (P < 0.001). Inner ring, outer ring, and mean macular thickness both in prototype and commercial OCT devices were found to be significantly different between normal subjects and advanced glaucomatous eyes (P < 0.001). The outer ring was the only macular parameter that could significantly differentiate between normal and early glaucoma with either the prototype or commercial OCT unit (P = 0.003, P = 0.008, respectively). The area under the receiver operator characteristic (AROC) curves comparing mean NFL thickness between normal and advanced glaucomatous eyes was 1.00 for both the prototype and commercial OCT devices for eyes scanned on both machines on the same day. The AROC comparing mean macular thickness in normal and advanced glaucomatous eyes scanned on both machines on the same day was 0.88 for the prototype OCT device and 0.80 for the commercial OCT. CONCLUSIONS: Both macular and NFL thickness as measured by OCT showed statistically significant correlations with glaucoma, although NFL thickness showed a stronger association than macular thickness. There was good correspondence between findings using both the prototype and commercial OCT units. Macular and NFL thickness measurements made with OCT may have usefulness in the clinical assessment of glaucoma.

PURPOSE: To determine if optical coherence tomography (OCT) measurements of nerve fiber layer (NFL) thickness can be used to predict the presence of visual field defects (VFD) associated with glaucoma. DESIGN: Quota-sampled, cross-sectional study. METHODS: Retrospective study of OCT NFL thickness measurements in 276 eyes of 276 subjects. All persons received OCT NFL thickness analysis; 136 eyes underwent frequency-doubling technology (FDT) perimetry; and 140 eyes underwent Swedish interactive threshold algorithm (SITA) perimetry. We defined a parameter called NFL(50), which is the NFL thickness value at which there was a 50% likelihood of a VFD with either SITA or FDT perimetry. We evaluated the use of NFL(50). RESULTS: The mean NFL thickness with (n = 68) and without (n = 68) a VFD in the FDT group was 93.2 microm +/- 22.6 and 108.4 microm +/- 14.1, respectively. The mean NFL thickness with (n = 70) and without (n = 70) a VFD in the SITA group was 78.9 microm +/- 24.8 and 103.0 microm +/- 18.0, respectively. The FDT mean NFL(50) value was 98.5 microm. The SITA mean NFL(50) value was 87.0 microm. The area under the receiver operator characteristic (AROC) curve for mean NFL was 0.73, and the positive predictive value (PPV) for FDT mean NFL(50) was 72.2%. For SITA mean NFL, the AROC was 0.79 and the PPV for NFL(50) was 77.2%. CONCLUSION: Nerve fiber layer thickness analysis using OCT may be clinically useful in identifying subjects who have visual field loss. However, the PPV suggests that OCT may need higher resolution and better reproducibility to enhance its sensitivity and specificity for population screening.

OBJECTIVE: To compare the ability of expert clinicians, using qualitative assessment of stereoscopic optic disc photographs, and confocal scanning laser ophthalmoscope imaging to discriminate between healthy persons and patients with early glaucoma. DESIGN: Comparative instrument validation study. PARTICIPANTS: Seventy-two healthy persons and 51 patients with early glaucoma (average visual field mean deviation, -3.6 dB). Early glaucoma was defined as a history of ocular hypertension and a reproducible visual field defect scoring 5 or less in the Advanced Glaucoma Intervention Study classification, regardless of optic disc appearance. INTERVENTION: Stereoscopic optic nerve head (ONH) photography and Heidelberg Retina Tomograph (HRT) imaging, (Heidelberg Engineering GmbH, Dossenheim, Germany). MAIN OUTCOME MEASURES: Ability of clinical assessment of stereoscopic ONH photographs and analysis of HRT parameters, taking into account the optic disc size, to detect early glaucomatous optic disc changes. RESULTS: The specificity of the majority opinion of five observers to detect early glaucomatous optic disc changes was 94.4%, with a sensitivity of 70.6%. Using the HRT analysis, the specificity was 95.8% and the sensitivity was 84. 3%. CONCLUSIONS: Heidelberg Retina Tomograph image analysis that takes into account the optic disc size is more sensitive than clinical assessment of stereoscopic optic disc photographs in distinguishing between healthy persons and patients with early glaucoma.