Pupil Size Associated with the Largest Iris Volume in Normal Chinese Eyes.

BACKGROUND: To determine the range of pupil size that has the largest iris volume in normal eyes. METHODS: 31 healthy adult Chinese volunteers underwent swept-source anterior segment OCT examination in both eyes. Pilocarpine 1% was instilled in a randomly selected eye (eye with induced miosis (ME)) of each participant to obtain iris volume (IV) measurements over a range of pupil sizes. OCT was performed prior to and one hour after pilocarpine in both ME and fellow eye (FE). Iris volume (IV), anterior chamber volume (ACV), anterior chamber depth (ACD), and pupil size (PS) were recorded. A scatter plot was used to depict the association between each pupil size and IV. RESULTS: The pupillary sizes for which IV was recorded in ME and FE ranged from 1.161 mm to 6.665 mm. The mean IV increased with miosis in both ME and FE; in 13 eyes, IV decreased with a decrease in pupillary size. PS between 3.812 and 6.665 mm was associated with an increase in IV, while PS between 3.159 and 5.54 mm was associated with a decrease. The relationship between PS and IV was in the shape of a downward parabola and was modeled using a quadratic equation (y = -1.3121x 2 + 8.8429x + 16.423, R 2 = 0.26886). The largest IV occurred at PS between 3 and 4 mm. CONCLUSIONS: The relationship between PS and IV in this study was in the shape of a downward parabola. The largest IV was recorded at a pupillary size between 3 and 4 mm. This trial is registered with ChiCTR-ROC-17013572.

Association between choroidal thickness and anterior chamber segment in eyes with narrow or open-angle.

AIM: To investigate the relationship between choroidal thickness and anterior chamber segment in subjects with eyes with narrow or open-angle. METHODS: The subfoveal choroidal thickness was measured with enhanced depth-imaging optical coherence tomography and anterior chamber parameters were measured with ultrasound biomicroscopy in one eye of 23 subjects with open-angle eyes and 38 subjects with narrow-angle eyes. The mean age was 59.52±7.04y for narrow-angle subjects and 60.76±7.23y for open-angle subjects (P=0.514). Multivariate linear regression analysis was performed to assess the association between choroidal thickness and narrow-angle parameters. RESULTS: There were no differences in subfoveal choroidal thickness between open- and narrow-angle subjects (P=0.231). Anterior chamber parameters, including central anterior chamber depth, trabecular iris angle, iris thickness 500 µm from the scleral spur (IT500), and ciliary body thickness at 1 mm and 2 mm from the scleral spur (CBT1, CBT2) showed significant differences between the two groups (P<0.05). Subfoveal choroidal thickness showed negative correlation (ß=-0.496, P=0.016) only with anterior chamber depth in the open-angle group and with age (ß=-0.442, P=0.003) and IT500 (ß=-0.399, P=0.008) in the narrow-angle group. However, subfoveal choroidal thickness was not correlated with trabecular iris angle, anterior chamber depth, ciliary body thickness, or central corneal thickness in the narrow-angle group. CONCLUSION: Choroidal thickness does not differ in the two groups and has not correlated with anterior chamber parameters in narrow-angle subjects, suggesting a lack of relationship between choroidal thickness and primary angle-closure glaucoma.

Comparison of two retinal nerve fibre layer thickness measurement patterns of RTvue optical coherence tomography.

BACKGROUND: To evaluate the agreement and repeatability between operator-dependent centring and automatic centring retinal nerve fibre layer thickness measurement patterns (RNFL3.45 and NHM4) of RTvue optical coherence tomography in normal and glaucomatous eyes. DESIGN: Cross-sectional observational study. PARTICIPANTS: A total of 153 eyes from 149 normal subjects and subjects with glaucoma were analysed. METHODS: The retinal nerve fibre layer thickness was measured using RNFL3.45 and NHM4 three times on the same day to determine the repeatability and agreement between the two scan patterns. MAIN OUTCOME MEASURES: Student's paired t-testing, intra-class correlation coefficient, coefficient of variation, test-retest viability, Pearson's correlation coefficient and Bland-Altman analysis of retinal nerve fibre layer thickness measurements. RESULTS: The difference between RNFL3.45 and NHM4 measurements was statistically significant by paired t-testing (P=0.003) only in severe glaucoma group. The Pearson's correlation test showed a high degree of correlation of the mean retinal nerve fibre layer thickness (r=0.949). Bland-Altman plots showed that the differences between RNFL3.45 and NHM4 were smaller at thicker retinal nerve fibre layer values, but larger at thinner retinal nerve fibre layer values. The intra-class correlation coefficient for RNFL3.45 (and lower 95% confidence interval) in normal and glaucomatous eyes was 0.990 (0.985 confidence interval) and 0.997 (0.995 confidence interval), respectively. The intra-class correlation coefficient for NHM4 in normal and glaucomatous eyes was 0.989 (0.983 confidence interval) and 0.995 (0.992 confidence interval), respectively. The test-retest variability for RNFL3.45 and NHM4 ranged from 3.98 to 9.75µm in normal eyes, and from 4.10 to 13.34µm in glaucomatous eyes. CONCLUSION: Measurements of retinal nerve fibre layer thickness by RNFL3.45 and NHM4 are in good agreement.

Comparative study of retinal nerve fibre layer measurement by RTVue OCT and GDx VCC.

AIM: To evaluate the diagnostic performances and correlations of retinal nerve fibre layer (RNFL) thickness measured by RTVue OCT and GDx variable corneal compensation (VCC). METHODS: The total and regional RNFL thickness were measured by RTVue OCT and GDx VCC in 62 normal eyes and 72 glaucomatous eyes of Chinese subjects. The RNFL thickness profiles of normal and glaucomatous eyes by RTVue OCT are plotted. Correlations of RNFL thickness measured by RTVue OCT and GDx VCC were assessed using the Pearson correlation. The discriminating abilities of the two techniques for detection of glaucoma were compared by the area under the receiver operating characteristic curves (AUC). RESULTS: RTVue OCT demonstrated double hump patterns in the RNFL profiles. In both normal and glaucomatous subjects, the peaks were located in the superotemporal (ST) and inferotemporal (IT) regions, and the troughs were located at the nasal (NU+NL) and temporal (TU+TL) regions. Despite poor agreement, a high correlation (r=0.821) was found between the mean RNFL measurements by RTVue OCT and GDx VCC. For RTVue OCT, the highest AUCs were mean RNFL (AUC=0.914) and inferior mean RNFL (AUC=0.909). The nerve fibre indicator (AUC=0.856) and inferior RNFL (AUC=0.852) achieved the highest AUCs among all the GDx VCC measurements. The mean RNFL in RTVue OCT had the greatest AUC in the two devices. There was a significant difference in comparing the AUCs of the mean RNFL thickness obtained by RTVue OCT and GDx VCC (p=0.009). CONCLUSIONS: Although there were absolute value differences in RNFL thickness, a high correlation was observed between RTVue OCT and GDx VCC. RTVue OCT shows a reasonable ability to distinguish normal from glaucomatous eyes.

Comparative study of anterior segment measurement with Pentacam and anterior segment optical coherence tomography.

OBJECTIVE: To evaluate the repeatability of central corneal thickness (CCT), anterior chamber volume (ACV), and central anterior chamber depth (CACD) measurements obtained using a Pentacam rotating Scheimpflug camera, and to examine their agreement with measurements obtained using an anterior segment optical coherence tomography (AS-OCT) imaging system. DESIGN: Observational cross-sectional study. PARTICIPANTS: Fifty eyes from 50 healthy subjects were recruited. METHODS: CCT, CACD, and ACV were measured. Subjects were re-examined twice within a week of the first measurements. Intrasession and intersession within-subject SD (Sw), precision (1.96 × Sw), coefficient of variation (CVw: 100 × Sw / overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility. Bland-Altman plots were used to assess agreements between Pentacam and AS-OCT measurements. RESULTS: For intrasession repeatability, CVw and ICC values were 0.78 and 0.98 for CCT, 0.92 and 0.99 for CACD, and 3.52 and 0.98 for ACV, respectively. For intersession repeatability, CVw and ICC values were 1.19 and 0.96 for CCT, 1.25 and 0.99 for CACD, and 3.96 and 0.96 for ACV, respectively. The AS-OCT CCT measurement (519.23 [SD 34.37] µm) was 18.53 µm less than the Pentacam measurement (537.76 [SD 31.84] µm). The Pentacam CACD measurement (3.03 [SD 0.32] mm) was 0.08 less than the AS-OCT measurement (3.11 [SD 0.31] mm). The Pentacam ACV measurement (165.56 [SD 34.86] µL) was 14.21 µL less than the AS-OCT measurement (179.77 [SD 34.57] µL). CONCLUSIONS: Although the Pentacam measurements of the anterior segment parameters were reliable, their agreement with the AS-OCT measurements was not sufficient.

[Significance of optic disc topography and retinal nerve fiber layer thickness measurement by spectral-domain OCT in diagnosis of glaucoma].

OBJECTIVE: To study the significance of optic disc tomography and retinal nerve fiber layer (RNFL) thickness measurement by spectral-domain optical coherence tomography (OCT) in the diagnosis of glaucoma. METHODS: It was a noninterventional, observational study. The optic disc topographic parameters and total and regional RNFL thickness were measured by RTVue OCT in 60 normal eyes and 97 glaucomatous eyes. One-way analysis of variance was used to compare the parameters above mentioned between normal and glaucomatous groups. The area under the receiver operating characteristic curve (AUC) and the sensitivity at 80% specificity were used to assess the ability of each testing parameter in the differentiation between normal and glaucoma eyes. RESULTS: There were statistically significant differences in all RTVue OCT measurement parameters (F = 1.024, P = 0.596;F = 36.519, 54.464, 27.659, 36.176, 20.562, 63.833, 30.031, 54.652, 98.146, 78.705, 99.839, 43.728, 75.720, 45.709, 39.380, 33.590, 66.887, 78.335, 45.485;P = 0.000) except disc area. The average RNFL thickness in normal, early, moderate and advanced glaucomatous eyes was 109.950, 93.313, 80.374 and 65.570 µm, respectively. Among the eight regions around the optic disc, the thickest RNFL was located at the inferotemporal (150.066 µm) and superotemporal (146.285 µm) regions in normal eyes, and the superotemporal (108.569, 103.420 and 88.708 µm in early, moderate and advanced glaucomatous eyes, respectively) and inferotemporal (108.201, 102.830 and 86.369 µm in early, moderate and advanced glaucomatous eyes, respectively) regions in glaucomatous eyes. Both in normal and glaucomatous eyes, the thinnest RNFL was located at the nasal and temporal regions, respectively. For optic disc topographic parameters, the highest AUC was vertical cup/disc ratio (AUC = 0.762, 0.946 and 0.988 in early, moderate and advanced glaucomatous eyes, respectively), and the sensitivity at 80% specificity was 62.2%, 76.5% and 99.2% in early, moderate and advanced glaucomatous eyes, respectively. For RNFL thickness, the highest AUC was superotemporal region RNFL thickness (AUC = 0.915) and the sensitivity at 80% specificity was 89.5% in early glaucomatous eyes. The highest AUC was inferior average RNFL thickness (AUC = 0.967) and the sensitivity at 80% specificity was 94.1% in moderate glaucomatous eyes. The highest AUC was average RNFL thickness (AUC = 0.985) and the sensitivity at 80% specificity was 99.2% in advanced glaucomatous eyes. Among the eight regions around the optic disc, RNFL thickness of region ST (AUC = 0.915, 0.926 and 0.966 in early, moderate and advanced glaucomatous eyes, respectively) achieved the highest AUC. RNFL thicknesses of the nasal and temporal regions showed the lowest AUCs. CONCLUSIONS: RTVue OCT shows fair discriminating ability in distinguishing normal from glaucomatous eyes. RTVue OCT is a useful equipment for the diagnosis of glaucoma.

Narrow- and open-angle measurements with anterior-segment optical coherence tomography and Pentacam™.

BACKGROUND AND OBJECTIVE: To assess the agreement of the Pentacam (Oculus, Wetzlar, Germany) and anterior-segment optical coherence tomography (AS-OCT) in measuring open and narrow angles. PATIENTS AND METHODS: Prospective observational case series in which 39 healthy normal subjects (39 eyes) and 25 patients with narrow angles (37 eyes) were enrolled between May and September 2008. The anterior chamber measurements were performed by AS-OCT and the Pentacam. RESULTS: There was no significant difference in the open-angle measurements between the Pentacam and AS-OCT (P > .05). However, in patients with narrow angles, the average values of nasal and temporal anterior chamber angles taken by the Pentacam were larger than those of AS-OCT (25.5° ± 5.66° and 25.77° ± 5.15° vs 13.40° ± 6.81° and 12.13° ± 6.47°; P < .001). CONCLUSION: Both AS-OCT and the Pentacam can reliably measure anterior chamber angles in healthy normal subjects. The difference in measuring narrow angles by the two instruments was due to inability to view the angle recess or the scleral spur with the Pentacam.

Measurement of anterior chamber volume with rotating scheimpflug camera and anterior segment optical coherence tomography.

BACKGROUND: Measurement of anterior segment parameters plays an important role in diagnosis and treatment of glaucoma. The objective of this study was to evaluate the repeatability and reproducibility of anterior chamber volume (ACV) measurements with rotating scheimpflug camera (RSC) and to examine agreement with anterior segment optical coherence tomography (AS-OCT). METHODS: Thirty nine healthy normal subjects were recruited from the Eye Center of Tongren Hospital. ACV was measured using RSC and AS-OCT in a randomly selected eye for each subject. For RSC measurements, both automatic and manual ACV measurements and 2 independent operators' ACV measurements were obtained. All subjects were invited for 3 visits within a week to evaluate repeatability and reproducibility of ACV measurement by RSC. Agreement was evaluated between RSC and AS-OCT. RESULTS: Good repeatability and reproducibility were found for both automatic and manual ACV measurements obtained by RSC. For intrasession repeatability, coefficient of variation (CVw) and intraclass correlation coefficient (ICC) values for automatic were 3.52% and 0.98; the values for manual were 3.44% and 0.97, respectively. For intersession reproducibility, the respective CVw and ICC values were 3.96% and 0.96. Good agreement was also found in 2 operators for both automatic and manual ACV measurements; nevertheless, poor agreement was found between RSC and AS-OCT (95% confidence interval (CI) for agreement of automatic RSC measurement versus AS-OCT were -96.3 to 72.8 microl and 95% CI for agreement of manual RSC measurement versus AS-OCT were between -41.7 to 10.1 microl). CONCLUSIONS: Both RSC automatic and manual ACV measurements showed good repeatability and reproducibility, and showed comparable agreement between 2 independent operators, but poor agreement was found between RSC and AS-OCT.

Evaluation of optic nerve head and retinal nerve fiber layer in early and advance glaucoma using frequency-domain optical coherence tomography.

BACKGROUND: Recent research has suggested that structural significant damage in the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) may precede visual field loss. Optical coherence tomography (OCT) has become an important tool which has contributed to earlier and more accurate diagnosis of glaucoma over the past decade. RTVue OCT was the first frequency-domain OCT (FD-OCT) device to offer comprehensive glaucoma analysis including an RNFL thickness map and optic disc morphology. The aim of this study was to evaluate and compare the performance of FD-OCT for the detection of early and advanced glaucoma from normal eyes. METHODS: This was a cross-sectional study consisting of 63 normal eyes, and 37 with early and 41 with advanced glaucoma. All patients underwent RNFL thickness and ONH parameter measurements on the RTVue OCT. Glaucoma variables obtained from RTVue OCT were compared between the groups. Discriminating power for early glaucoma detection was expressed by using the analyses of area under the receiver operating characteristic curves (AUCs). RESULTS: All RNFL thickness and ONH parameters but disc area showed significant differences between the normal and the glaucoma groups, and the highest AUCs for RNFL thickness was average thickness (AUC = 0.816) and for ONH parameters was cup/disc vertical ratio (AUC = 0.782). They were the best parameters for discriminating normal from early glaucomatous eyes. CONCLUSIONS: Frequency-domain OCT (RTVue OCT) may offer comprehensive analysis for RNFL thickness and ONH, which showed good diagnostic ability in distinguishing normal from glaucomatous eyes.