Relationship between macular thickness measurement and signal strength using Stratus optical coherence tomography.

PURPOSE: To examine the relationship between signal strength and macular thickness as measured by Stratus optical coherence tomography (OCT)'s fast macular thickness protocol in healthy subjects. METHODS: In this prospective cross-sectional study 79 eyes of 42 healthy subjects were enrolled. The age, gender, and eye (right vs left) of each subject were recorded. The Stratus OCT fast macular thickness scan protocol was used and the macular thickness was measured with retinal thickness map analysis. Each eye was imaged at least six times to acquire images with signal strengths of 4, 5, 6, 7, 8, and 9 out of 10 via adjustment of the focusing knob. The OCT parameters included in the analysis were thickness in the central 1 mm and in the different quadrants in the 3-mm area. RESULTS: Overall 79 eyes of 42 patients with a mean age of 38.4±12.4 were included. There was no significant difference between the signal strength measurements obtained with different signal strengths in the central thickness (P=0.20). In the superior, nasal, inferior, and temporal quadrants, a signal strength of 8 demonstrated up to 3 µm thicker measurements than a signal strength of 5 (P<0.05). In general linear regression analysis, after accounting for age and gender, signal strength did not remain a significant predictor of thickness in any quadrant. CONCLUSIONS: When using fast map macular measurements, a signal strength of 5 is clinically as efficient as a signal strength of 8 in measuring macular thickness in all quadrants. Insisting on higher signal strength may not be necessary.

Comparison and interchangeability of macular thickness measured with Cirrus OCT and Stratus OCT in myopic eyes.

AIM: To investigate the difference of macular thickness measurements between stratus optical coherence tomography (OCT) and Cirrus OCT (Carl Zeiss Meditec, Dublin, CA, USA) in the same myopic patient and to develop a conversion equation to interchange macular thickness obtained with these two OCT devices. METHODS: Eighty-nine healthy Chinese adults with spherical equivalent (SE) ranging from -1.13 D to -9.63 D were recruited. The macular thickness was measured by Cirrus OCT and Stratus OCT. The correlation between macular thickness and axial length and the agreement between two OCT measurements were evaluated. A formula was generated to interchange macular thickness obtained with two OCT devices. RESULTS: Average macular thickness measured with Stratus OCT (r=-0.280, P=0.008) and Cirrus OCT (r=-0.224, P=0.034) were found to be negatively correlated with axial length. No statistically significant correlation was found between axial length and central subfield macular thickness (CMT) measured with Stratus OCT (r=0.191, P=0.073) and Cirrus OCT (r=0.169, P=0.113). The mean CMT measured with Cirrus OCT was 53.63±7.94 µm thicker than with Stratus OCT. The formula CMTCirrus OCT=78.328+0.874×CMTStratus OCT was generated to interchange macular thickness obtained with two OCT devices. CONCLUSION: Macular thickness measured with Cirrus OCT were thicker than with Stratus OCT in myopic eyes. A formula can be used to interchange macular thickness measured with two OCT devices in myopic eyes. Studies with different OCT devices and larger samples are warranted to enable the comparison of macular values measured with different OCT devices.

Changes of Peripapillary Retinal Nerve Fiber Layer Thickness Profile According to Aging in Myopic Eyes

PURPOSE: To evaluate the effects of age on the distributional variability of peripapillary retinal nerve fiber layer (RFNL) thickness measured by optical coherence tomography (OCT) in myopia. METHODS: Only the right eye of 64 myopic patients with long axial length (> or =24.5 mm) was included in the present study. The patients were divided into 2 age groups, 20 to 39 years of age and 40 to 59 years of age. Eventually, 42 subjects were selected and matched based on the difference of axial length not exceeding 0.5 mm between subjects in each group. The RFNL thickness was measured using Stratus OCT and average thickness, angular locations of double humps, and false-positive rate were compared. RESULTS: In both groups, the distribution of RNFL thickness in a double hump pattern was observed, which had a deviation to the temporal side only in the younger myopic eye group, but not in the middle-aged group. The middle-aged group had significantly thinner RNFL in 1, 7, and 8 clock-hour sectors compared to the younger myopic eyes (p < or = 0.02). Probability of abnormal OCT parameters at the 5% level of the 2 groups with the built-in RNFL normative database was not significantly different. CONCLUSIONS: The variability of RFNL thickness distribution related to axial length was less observed in the middle-aged group than the younger-aged group. These results should be considered in glaucoma diagnosis when using OCT.

Structural and functional relationships in glaucoma using standard automated perimetry and the Humphrey Matrix.

PURPOSE: To evaluate and compare correlations between structural and functional loss in glaucoma as assessed by optical coherence tomography (OCT), scanning laser polarimetry (GDx VCC, as this was the model used in this study), standard automated perimetry (SAP), and the Humphrey Matrix (Matrix). METHODS: Ninety glaucomatous eyes identified with SAP and 112 eyes diagnosed using Matrix were independently classified into six subgroups, either S1/M1 (MD>-6dB), S2/M2 (-12

Structural and Functional Relationships in Glaucoma Using Standard Automated Perimetry and the Humphrey Matrix

PURPOSE: To evaluate and compare correlations between structural and functional loss in glaucoma as assessed by optical coherence tomography (OCT), scanning laser polarimetry (GDx VCC, as this was the model used in this study), standard automated perimetry (SAP), and the Humphrey Matrix (Matrix). METHODS: Ninety glaucomatous eyes identified with SAP and 112 eyes diagnosed using Matrix were independently classified into six subgroups, either S1/M1 (MD>-6dB), S2/M2 (-12

Comparison of Macular Thickness Measurements Between Fourier-Domain and Time-Domain Optical Coherence Tomography in Normal Eyes and Eyes With Macular Diseases

PURPOSE: To define and measure macular thickness and volume using Fourier domain OCT (FD OCT) and compare the values with Stratus OCT in normal eyes and eyes with macular disease. METHODS: On the same day, macular thicknesses of the ETDRS 9 subfield and total macular volumes were measured in 35 eyes of 23 normal subjects and 19 diseased eyes of 24 patients with FD OCT and Stratus OCT. The macular cube scan protocol for FD OCT and the fast macular thickness map protocol for Stratus OCT were used to measure macular thicknesses. RESULTS: Foveal thickness of the central subfield in FD OCT (251.49+/-79.45 micrometer) was thicker than the value of Stratus OCT (210.26+/-60.57 micrometer) (p<0.001) in all eyes. Total macular volume was 7.72+/-1.06 mm3 and 7.04+/-0.96 mm3 for FD OCT and Stratus OCT, respectively (p<0.001). Retina thickness of the ETDRS 9 subfields in FD OCT was thicker than the value obtained using Stratus OCT. In addition, foveal thickness differences were statistically significant in both the normal and diseased eye groups. CONCLUSIONS: Macular thickness and total macular volume as measured by the FD OCT were larger than the values obtained using the Stratus OCT in both the normal and the diseased eye groups. The measuring algorithm of FD OCT defines the top of RPE as the outer retinal boundary, but Stratus OCT defines the outer retinal boundary as the IS/OS junction of the photoreceptor. Therefore, macular thicknesses of FD OCT are thicker than those of Stratus OCT. This difference should be considered when comparing the results of FD OCT with those of Stratus OCT.

Comparison of Frequency Doubling Technology Perimeter and RNFL Photography for Early Diagnosis of Glaucoma

PURPOSE: To compare the frequency doubling technology perimeter (FDT) with retinal nerve fiber layer (RNFL) photography as a tool for the early detection of glaucoma. METHODS: Ninety-eight eyes of 98 patients were evaluated over a period of 3 months. According to the results of RNFL photography and FDT, Patients were divided into four groups based on the results of RNFL photography and optical coherence tomography (OCT). A comparison of the RNFL thickness of each group was performed using the OCT results. RESULTS: RNFL thickness in the group with abnormal FDT and normal RNFL were significantly decreased from those in the group with normal FDT and RNFL photography at the 6, 7 and, 10 o'clock area (p<0.05). CONCLUSIONS: There were statistically significant differences in the RNFL thickness between the group with abnormal FDT and normal RNFL photography, and the group with normal FDT and RNFL photography within the limited areas. These results imply that FDT is more useful for the early detection of glaucoma than RNFL photography.

Stratus OCT, SWAP, Matrix FDT in Preperimetric Glaucoma

PURPOSE: To evaluate the peripapillary retinal nerve fiber layer (RNFL) thickness with optical coherence tomography (OCT) in normal subjects and preperimetric glaucoma patients, as well as compare the results of OCT, short wavelength automated perimetry (SWAP), frequency doubling technology perimetry (FDT) in preperimetric glaucoma patients. METHODS: Thirty-six eyes of 36 preperimetric glaucoma patients who have definitive localized RNFL defects in disc photograph and normal standard visual field, as well as 35 eyes of 35 normal subjects, were enrolled in this study. We compared the peripapillary RNFL thickness between the two groups using Stratus OCT. Stratus OCT, FDT, and SWAP results in preperimetric glaucoma group were also compared. RESULTS: Compared with normal controls, peripapillary RNFL thickness, including the average, superior, and inferior quadrant, was significantly low (P<0.05) in the preperimetric glaucoma group, 93.40+/-11.16 micrometer, 118.33+/-21.17 micrometer, and 108.72+/-16.76 micrometer respectively. In preperimetric glaucoma group, functional and structural abnormalities were found in 55.6% with Stratus OCT, 31.4% with SWAP, and 79.4% with Matrix FDT. CONCLUSIONS: Statistically significant reduction of RNFL thickness was revealed in the preperimetric glaucoma group, and Matrix FDT was the most sensitive test for detecting early glaucomatous change, followed by Stratus OCT, and SWAP.

Diagnosis of Glaucoma in the Cases of the Opposed Results of GDx and OCT

PURPOSE: To investigate the coincidence of visual field loss in cases with different GDx VCC and Stratus OCT results, and to analyze the cause of these differences. METHODS: We retrospectively reviewed the medical records of patients who had visited our hospital for glaucoma evaluation from September 2003 to August 2005 for sensitivity, specificity, positive predictive rate, and negative predictive rate of GDx and OCT. In order to analyze the cause of discrepancy between the GDx and OCT results, we divided patients into Group A, consisting of GDx abnormal and OCT normal eyes, and Group B, consisting of GDx normal and OCT abnormal eyes. We compared optic disc tilting, peripapillary atrophy, and cup-disc ratio between the two groups. RESULTS: In cases of differing results between GDx and OCT, sensitivity, specificity, positive predictive rate and negative predictive rate were higher in Stratus OCT than in GDx. Peripapillary atrophy did not represent a statistically significant difference between group A and group B (p=0.601), where as the difference in cup-disc ratio between the two groups was statistically significant (p=0.000). CONCLUSIONS: OCT parameters coincided better than GDx with cases having different results on GDx and OCT. In cases with a large cup/disc ratio, there was a tendency to be normal according to GDx and abnormal by OCT.