Idiopathic juxtafoveal retinal telangiectasis: new findings by ultrahigh-resolution optical coherence tomography.

OBJECTIVE: To investigate the capabilities of ultrahigh-resolution optical coherence tomography (UHR OCT); to compare with the commercially available OCT standard-resolution system, StratusOCT, for imaging of idiopathic juxtafoveal retinal telangiectasis (IJT); and to demonstrate that UHR OCT provides additional information on disease morphology, pathogenesis, and management. DESIGN: Retrospective, observational, interventional case series. PARTICIPANTS: Nineteen eyes of 10 patients diagnosed with IJT in at least one eye. METHOD: All patients were imaged with UHR OCT and StratusOCT at the same visit. A subset of patients was also imaged before and after treatment of IJT. MAIN OUTCOME MEASURES: Ultrahigh- and standard-resolution cross-sectional tomograms of IJT pathology. RESULTS: Using both standard- and ultrahigh-resolution OCT, we identified the following features of IJT: (1) a lack of correlation between retinal thickening on OCT and leakage on fluorescein angiography, (2) loss and disruption of the photoreceptor layer, (3) cystlike structures in the foveola and within internal retinal layers such as the inner nuclear or ganglion cell layers, (4) a unique internal limiting membrane draping across the foveola related to an underlying loss of tissue, (5) intraretinal neovascularization near the fovea, and (6) central intraretinal deposits and plaques. In 63% of cases, the presence of abnormal vessels and a discontinuity of the photoreceptor layer correlated with visual acuity. CONCLUSIONS: Ultrahigh-resolution OCT improves visualization of the retinal pathology associated with IJT and allows identification of new features associated with it. Some of these features, such as discontinuity of the photoreceptor layer, are revealed only by UHR OCT.

Comparison of ultrahigh- and standard-resolution optical coherence tomography for imaging macular pathology.

OBJECTIVE: To compare ultrahigh-resolution optical coherence tomography (UHR OCT) with standard-resolution OCT for imaging macular diseases, develop baselines for interpreting OCT images, and identify situations where UHR OCT can provide additional information on disease morphology. DESIGN: Cross-sectional study. PARTICIPANTS: One thousand two eyes of 555 patients with different macular diseases including macular hole, macular edema, central serous chorioretinopathy, age-related macular degeneration (AMD), choroidal neovascularization, epiretinal membrane, retinal pigment epithelium (RPE) detachment, and retinitis pigmentosa. METHODS: A UHR ophthalmic OCT system that achieves 3-microm axial image resolution was developed for imaging in the ophthalmology clinic. Comparative studies were performed with both UHR OCT and standard 10-microm-resolution OCT. Standard scanning protocols of 6 radial 6-mm scans through the fovea were obtained with both systems. Ultrahigh-resolution OCT and standard-resolution OCT images were correlated with standard ophthalmic examination techniques (dilated ophthalmoscopy, fluorescein angiography, indocyanine green angiograms) to assess morphological information contained in the images. MAIN OUTCOME MEASURES: Ultrahigh-resolution and standard-resolution OCT images of macular pathologies. RESULTS: Correlations of UHR OCT images, standard-resolution images, fundus examination, and/or fluorescein angiography were demonstrated in full-thickness macular hole, central serous chorioretinopathy, macular edema, AMD, RPE detachment, epiretinal membrane, vitreal macular traction, and retinitis pigmentosa. Ultrahigh-resolution OCT and standard-resolution OCT exhibited comparable performance in differentiating thicker retinal layers, such as the retinal nerve fiber, inner and outer plexiform, and inner and outer nuclear. Ultrahigh-resolution OCT had improved performance differentiating finer structures or structures with lower contrast, such as the ganglion cell layer and external limiting membrane. Ultrahigh-resolution OCT confirmed the interpretation of features, such as the boundary between the photoreceptor inner and outer segments, which is also visible in standard-resolution OCT. The improved resolution of UHR OCT is especially advantageous in assessing photoreceptor morphology. CONCLUSIONS: Ultrahigh-resolution OCT enhances the visualization of intraretinal architectural morphology relative to standard-resolution OCT. Ultrahigh-resolution OCT images can provide a baseline for defining the interpretation of standard-resolution images, thus enhancing the clinical utility of standard OCT imaging. In addition, UHR OCT can provide additional information on macular disease morphology that promises to improve understanding of disease progression and management.

Optical coherence tomography longitudinal evaluation of retinal nerve fiber layer thickness in glaucoma.

OBJECTIVES: To longitudinally evaluate optical coherence tomography (OCT) peripapillary retinal nerve fiber layer thickness measurements and to compare these measurements across time with clinical status and automated perimetry. METHODS: Retrospective evaluation of 64 eyes (37 patients) of glaucoma suspects or patients with glaucoma participating in a prospective longitudinal study. All participants underwent comprehensive clinical assessment, visual field (VF) testing, and OCT every 6 months. Field progression was defined as a reproducible decline of at least 2 dB in VF mean deviation from baseline. Progression of OCT was defined as reproducible mean retinal nerve fiber layer thinning of at least 20 mum. RESULTS: Each patient had a median of 5 usable OCT scans at median follow-up of 4.7 years. The difference in the linear regression slopes of retinal nerve fiber layer thickness between glaucoma suspects and patients with glaucoma was nonsignificant for all variables; however, Kaplan-Meier survival curve analysis demonstrated a higher progression rate by OCT vs VF. Sixty-six percent of eyes were stable throughout follow-up, whereas 22% progressed by OCT alone, 9% by VF mean deviation alone, and 3% by VF and OCT. CONCLUSIONS: A greater likelihood of glaucomatous progression was identified by OCT vs automated perimetry. This might reflect OCT hypersensitivity or true damage identified by OCT before detection by conventional methods.

Comparison of ultrahigh- and standard-resolution optical coherence tomography for imaging macular hole pathology and repair.

PURPOSE: To compare ultrahigh-resolution optical coherence tomography (UHR-OCT) technology to a standard-resolution OCT instrument for the imaging of macular hole pathology and repair; to identify situations where UHR-OCT provides additional information on disease morphology, pathogenesis, and management; and to use UHR-OCT as a baseline for improving the interpretation of the standard-resolution images. DESIGN: Observational and interventional case series. PARTICIPANTS: Twenty-nine eyes of 24 patients clinically diagnosed with macular hole in at least one eye. METHODS: A UHR-OCT system has been developed and employed in a tertiary-care ophthalmology clinic. Using a femtosecond laser as the low-coherence light source, this new UHR-OCT system can achieve an unprecedented 3-mum axial resolution for retinal OCT imaging. Comparative imaging was performed with UHR-OCT and standard 10-mum resolution OCT in 29 eyes of 24 patients with various stages of macular holes. Imaging was also performed on a subset of the population before and after macular hole surgery. MAIN OUTCOME MEASURES: Ultrahigh- and standard-resolution cross-sectional OCT images of macular hole pathologies. RESULTS: Both UHR-OCT and standard-resolution OCT exhibited comparable performance in differentiating various stages of macular holes. The UHR-OCT provided improved imaging of finer intraretinal structures, such as the external limiting membrane and photoreceptor inner segment (IS) and outer segment (OS), and identification of the anatomy of successful surgical repair. The improved resolution of UHR-OCT enabled imaging of previously unidentified changes in photoreceptor morphology associated with macular hole pathology and postoperative repair. Visualization of the junction between the photoreceptor IS and OS was found to be an important indicator of photoreceptor integrity for both standard-resolution and UHR-OCT images. CONCLUSIONS: Ultrahigh-resolution optical coherence tomography improves the visualization of the macular hole architectural morphology. The increased resolution of UHR-OCT enables the visualization of photoreceptor morphology associated with macular holes. This promises to lead to a better understanding of the pathogenesis of macular holes, the causes of visual loss secondary to macular holes, the timing of surgical repair, and the evaluation of postsurgical outcome. Ultrahigh-resolution optical coherence tomography imaging of macular holes that correspond to known alterations in retinal morphology can be used to interpret retinal morphology in UHR-OCT images. Comparisons of UHR-OCT images with standard-resolution OCT images can establish a baseline for the better interpretation of clinical standard-resolution OCT images. The ability to visualize photoreceptors and their integrity or impairment is an indicator of macular hole progression and surgical outcome.

Reproducibility of nerve fiber thickness, macular thickness, and optic nerve head measurements using StratusOCT.

PURPOSE: The measurement reproducibility of the third generation of commercial optical coherence tomography, OCT-3 (StratusOCT, software ver. A2, Carl Zeiss Meditec Inc., Dublin, CA) was investigated. The nerve fiber layer (NFL) thickness, macula thickness map, and optic nerve head (ONH) parameters in normal eyes were studied. METHODS: Ten normal subjects were imaged six times (three before and three after dilation) per day, and the series was repeated on three different days. The order of the scans before pupil dilation was randomized in each of the 3 days of scanning. After pupil dilation, the scans were also randomized in each of the 3 days of scanning. Each series was performed separately for standard-density (128 A-scans per macular and ONH image and 256 A-scans per NFL image) and high-density (512 A-scans per image for all three scan types) scanning. RESULTS: The mean macular thickness was 235 +/- 9.8 micro m. A-scan density (or image acquisition speed) had a statistically significant effect (P < 0.05) on the reproducibility of the mean macular thickness, macular volume, and a few sectors of the macular map. No significant dilation effect was found for any of the macular parameters. The best intraclass correlation coefficient (ICC; 94%) for macular scans was found for dilated high-density scanning, with an intervisit SD of 2.4 micro m and an intravisit SD of 2.2 micro m. The mean NFL thickness for standard scanning was 98 +/- 9 micro m. NFL reproducibility showed mixed results and had interactions between scan density and dilation for some parameters. For most of the NFL parameters, reproducibility was better with dilated standard-density scanning. The mean NFL thickness ICC for dilated standard scanning was 79%, with an intervisit SD of 2.5 micro m and an intravisit SD of 1.6 micro m. For the ONH analysis, the reproducibility was better for dilated standard-density scanning for almost all the parameters, except for disc area, horizontal integrated rim volume, and vertical integrated rim area, which were better before dilation. The best reproducibility was found for cup-to-disc ratio (ICC = 97%, with intervisit SD of 0.04 micro m and intravisit SD of 0.02 micro m). CONCLUSIONS: StratusOCT demonstrated reproducible measurements of NFL thickness, macular thickness, and optic nerve head parameters. The best reproducibility was found for dilated standard scanning for NFL and ONH parameters and for dilated high-density scanning for macular parameters.

Optical coherence tomography disc assessment in optic nerves with peripapillary atrophy.

BACKGROUND AND OBJECTIVE: Optical coherence tomography (OCT) is able to determine the optic disc margin automatically. The aim of this study was to investigate the accuracy of the automatic OCT optic nerve head measurements in the presence of peripapillary atrophy. PATIENTS AND METHODS: This was a cross-sectional, retrospective study. Thirty-one subjects with peripapillary atrophy underwent optic nerve head scanning with OCT version 3. Nineteen of the eyes were classified clinically as having glaucoma, nine had suspected glaucoma, and three were normal. Automatic OCT results were compared with manual tracing results. RESULTS: Significant differences were found between most OCT optic nerve head automated and manual disc assessment parameters; however, good agreement was found between the two methods for all parameters (intraclass correlation, 0.71 to 0.94). Areas under receiver operator characteristics curves for clinical status were similar for all parameters with both methods. CONCLUSION: Automated OCT optic nerve head analysis may be used in the clinical setting in the presence of peripapillary atrophy; however, caution should be used when comparing individual results with population-derived optic nerve head results.

Absolute frequency-domain pulse oximetry of the brain: methodology and measurements.

A new method to non-invasively measure the absolute tissue oxygen saturation (SO2) and arterial oxygen saturation (fdSaO2) by frequency-domain spectroscopy is described. This method is based on the quantitative measurement of the tissue absorption spectrum, which is used to determine global SO2. From the amplitude of absorption changes caused by arterial pulsation oscillations, in the range of 633-841 nm, the fdSaO2 can be calculated. During deoxygenation (air/N2 mixture) experiments, we measured the fdSaO2 and SO2 on the forehead of three healthy volunteers and compared them to the arterial oxygen saturation measured by conventional pulse oximetry (poSaO2) on the finger. fdSaO2 and poSaO2 agree very well (mean difference: -1.2 +/- 2.6%). Changes in SO2 were systematically smaller than in fdSaO2 or poSaO2 probably due to autoregulation. The measurements with 4 and 8 wavelengths had comparable quality.

Comparison of optic nerve head measurements obtained by optical coherence tomography and confocal scanning laser ophthalmoscopy.

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.