DETECTION OF MICROVASCULAR CHANGES IN EYES OF PATIENTS WITH DIABETES BUT NOT CLINICAL DIABETIC RETINOPATHY USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: To evaluate the ability of optical coherence tomography angiography to detect early microvascular changes in eyes of diabetic individuals without clinical retinopathy. METHODS: Prospective observational study of 61 eyes of 39 patients with diabetes mellitus and 28 control eyes of 22 age-matched healthy subjects that received imaging using optical coherence tomography angiography between August 2014 and March 2015. Eyes with concomitant retinal, optic nerve, and vitreoretinal interface diseases and/or poor-quality images were excluded. Foveal avascular zone size and irregularity, vessel beading and tortuosity, capillary nonperfusion, and microaneurysm were evaluated. RESULTS: Foveal avascular zone size measured 0.348 mm² (0.1085-0.671) in diabetic eyes and 0.288 mm² (0.07-0.434) in control eyes (P = 0.04). Foveal avascular zone remodeling was seen more often in diabetic than control eyes (36% and 11%, respectively; P = 0.01). Capillary nonperfusion was noted in 21% of diabetic eyes and 4% of control eyes (P = 0.03). Microaneurysms and venous beading were noted in less than 10% of both diabetic and control eyes. Both diabetic and healthy control eyes demonstrated tortuous vessels in 21% and 25% of eyes, respectively. CONCLUSION: Optical coherence tomography angiography was able to image foveal microvascular changes that were not detected by clinical examination in diabetic eyes. Changes to the foveal avascular zone and capillary nonperfusion were more prevalent in diabetic eyes, whereas vessel tortuosity was observed with a similar frequency in normal and diabetic eyes. Optical coherence tomography angiography may be able to detect diabetic eyes at risk of developing retinopathy and to screen for diabetes quickly and noninvasively before the systemic diagnosis is made.

Choroidal thickness in retinal pigment epithelial tear as measured by spectral domain optical coherence tomography.

PURPOSE: To evaluate the choroidal thickness with spectral domain optical coherence tomography in subjects with retinal pigment epithelial (RPE) tear compared with the choroidal thickness of their fellow eye. METHODS: For this cross-sectional investigation, seven eyes of seven patients with neovascular age-related macular degeneration and RPE tear in one eye imaged with spectral domain optical coherence tomography were identified. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500 µm intervals up to 2,500 µm temporal and nasal to the fovea in both the eye with the RPE tear and the eye with intact RPE. All measurements were performed by two independent observers and averaged for the purpose of the analysis. Measurements were compared using paired t-test. RESULTS: The average age of patients was 79 years (range, 66-88 years). All subjects had dome-shaped pigment epithelial detachments before RPE tear and no dome-shaped pigment epithelial detachments in the unaffected eye. Average subfoveal choroidal thickness in the eye with the RPE tear was 154.9 ± 10.1 µm. Average subfoveal choroidal thickness in the eye with intact RPE was 212.9 ± 10.6 µm (P = 0.035). CONCLUSION: There is a significant decrease in subfoveal choroidal thickness in the subjects with RPE tear compared with their fellow eye with intact RPE. It is unclear if this thinning is a consequence of or precedes the RPE tear. Further studies are necessary to prospectively follow choroidal thickness in subjects with dome-shaped pigment epithelial detachments.

Analysis of choroidal morphologic features and vasculature in healthy eyes using spectral-domain optical coherence tomography.

OBJECTIVE: To analyze the morphologic features and vasculature of the choroid in healthy eyes using spectral-domain (SD) optical coherence tomography (OCT). DESIGN: Cross-sectional retrospective review. PARTICIPANTS: Forty-two healthy subjects (42 eyes) with no ocular disease who underwent high-definition scanning with Cirrus high-definition OCT (Carl Zeiss Meditec, Inc., Dublin, CA) at the New England Eye Center, Boston, Massachusetts, between November 2009 and September 2010. METHODS: The SD OCT images were evaluated for morphologic features of the choroid, including the shape of the choroid-scleral border, location of the thickest point of choroid, and regions of focal choroidal thinning. Total choroidal thickness and large choroidal vessel layer thickness were measured by 2 independent observers experienced in analyzing OCT images using the Cirrus linear measurement tool at the fovea, 750 µm nasal and temporal to the fovea. Custom software was used to calculate the ratio of choroidal stroma to the choroidal vessel lumen. MAIN OUTCOME MEASURES: Qualitative assessment of the choroidal morphologic features, quantitative analysis of choroidal vasculature, and use of novel automated software to determine the ratio of choroidal stromal area to the area of choroidal vessel lumen. RESULTS: The 42 subjects had a mean age of 51.6 years. All subjects (100%) had a so-called bowl or convex shape to the choroid-sclera junction, and the thickest point of the choroid was under the fovea in 88.0% of the subjects. The mean choroidal thickness was 256.8 ± 75.8 µm, mean thickness of the large choroidal vessel layer was 204.3 ± 65.9 µm, and that of the medium choroidal vessel layer-choriocapillaris layer was 52.9 ± 20.6 µm beneath the fovea. The ratio of large choroidal vessel layer thickness to the total choroidal thickness beneath the fovea was 0.7 ± 0.06. The software-generated ratio of choroidal stromal area to the choroidal vessel lumen area was 0.27 ± 0.08, suggesting that choroidal vessel lumen forms a greater proportion of the choroid than the choroidal stroma in healthy eyes. CONCLUSIONS: This is the first study to describe the morphologic features and vasculature of the choroid in healthy eyes from 1-line raster scans obtained using SD OCT. The method described holds promise and has immediate clinical usefulness in recognizing subtle changes in choroidal morphologic features and the role of choroidal angiopathy in various disease states that, in the future, may inform new treatment methods. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Reproducibility of choroidal thickness measurements across three spectral domain optical coherence tomography systems.

PURPOSE: To investigate the reproducibility of choroidal thickness measurements in normal subjects on 3 spectral domain optical coherence tomography (SD-OCT) instruments: Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), and Optovue RTVue (Optovue Inc., Fremont, CA). DESIGN: Cross-sectional non-interventional study. PARTICIPANTS: Images were obtained in 28 eyes of 28 healthy undilated volunteers without ocular pathology in a clinical setting. METHODS: All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging (EDI), and RTVue retina-cross. MAIN OUTCOME MEASURES: The choroid was measured subfoveally, 750 µm temporal, and 750 µm nasal to the fovea. All measurements were performed by 2 independent observers. Two-way analysis of variance (ANOVA) with Bonferroni's post-test, Pearson correlation, and Bland-Altman analysis were used to compare measurements. RESULTS: The group of 28 subjects consisted of 7 men and 21 women, with an average age of 35.2 years (range, 23-64 years). A 2-way ANOVA with Bonferroni's post-test revealed no significant difference in the average subfoveal choroidal thickness (P > 0.05) among systems for any location: subfoveally, 750 µm temporal, and 750 µm nasal to the fovea. The measurements of choroidal thickness from any pair of 3 instruments (Cirrus vs. Spectralis, Cirrus vs. RTVue, Spectralis vs. RTVue) were also strongly correlated. The Pearson correlation among all 2 system pairs of the 3 systems was greater than 0.9 (P < 0.0001). The 95% limits of agreement among 4 choroidal thickness measurements were +11.21% to -13.57% (bias -1.17) between Cirrus and RTVue, +10.85% to -12.45% (bias -0.80) between Spectralis and RTVue, and +12.81% to -13.33% (bias -0.25) between Cirrus and Spectralis. CONCLUSIONS: In our population of young healthy adults with normal vision, there was good reproducibility among choroidal thickness measurements of images acquired with Cirrus, Spectralis, and RTVue. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Choroidal imaging using spectral-domain optical coherence tomography.

BACKGROUND: A structurally and functionally normal choroidal vasculature is essential for retinal function. Therefore, a precise clinical understanding of choroidal morphology should be important for understanding many retinal and choroidal diseases. METHODS: PUBMED (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed) was used for most of the literature search for this article. The criterion for inclusion of an article in the references for this review was that it included materials about both the clinical and the basic properties of choroidal imaging using spectral-domain optical coherence tomography. RESULTS: Recent reports show successful examination and accurate measurement of choroidal thickness in normal and pathologic states using spectral-domain optical coherence tomography systems. This review focuses on the principles of the new technology that make choroidal imaging using optical coherence tomography possible and on the changes that subsequently have been documented to occur in the choroid in various diseases. Additionally, it outlines future directions in choroidal imaging. CONCLUSION: Optical coherence tomography is now proven to be an effective noninvasive tool to evaluate the choroid and to detect choroidal changes in pathologic states. Additionally, choroidal evaluation using optical coherence tomography can be used as a parameter for diagnosis and follow-up.

Choroidal thickness in patients with diabetic retinopathy analyzed by spectral-domain optical coherence tomography.

PURPOSE: This study was designed to examine choroidal thickness in patients with diabetes using spectral-domain optical coherence tomography. METHODS: Forty-nine patients (49 eyes) with diabetes and 24 age-matched normal subjects underwent high-definition raster scanning using spectral-domain optical coherence tomography with frame enhancement software. Patients with diabetes were classified into 3 groups: 11 patients with mild or moderate nonproliferative diabetic retinopathy and no macular edema, 18 patients with nonproliferative diabetic retinopathy and diabetic macular edema, and 20 patients with treated proliferative diabetic retinopathy and no diabetic macular edema (treated proliferative diabetic retinopathy). Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-µm intervals up to 2,500 µm temporal and nasal to the fovea. RESULTS: Reliable measurements of choroidal thickness were obtainable in 75.3% of eyes examined. Mean choroidal thickness showed a pattern of thinnest choroid nasally, thickening in the subfoveal region, and thinning again temporally in normal subjects and patients with diabetes. Mean subfoveal choroidal thickness was thinner in patients with diabetic macular edema (63.3 µm, 27.2%, P < 0.05) or treated proliferative diabetic retinopathy (69.6 µm, 30.0%, P < 0.01), compared with normal subjects. There was no difference between nonproliferative diabetic retinopathy and normal subjects. CONCLUSION: Choroidal thickness is altered in diabetes and may be related to the severity of retinopathy. Presence of diabetic macular edema is associated with a significant decrease in the choroidal thickness.

Analysis of normal peripapillary choroidal thickness via spectral domain optical coherence tomography.

PURPOSE: To analyze the normal peripapillary choroidal thickness utilizing a commercial spectral domain optical coherence tomography (OCT) device and determine the intergrader reproducibility of this method. DESIGN: Retrospective, noncomparative, noninterventional case series. PARTICIPANTS: Thirty-six eyes of 36 normal patients seen at the New England Eye Center between April and September 2010. METHODS: All patients underwent high-definition scanning with the Cirrus HD-OCT. Two raster scans were obtained per eye, a horizontal and a vertical scan, both of which were centered at the optic nerve. Two independent graders individually measured the choroidal thickness. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid-scleral junction at 500-µm intervals away from the optic nerve in the superior, inferior, nasal, and temporal quadrants. Statistical analysis was conducted to compare mean choroidal thicknesses. Intergrader reproducibility was assessed by intraclass correlation coefficient and Pearson's correlation coefficient. Average choroidal thickness in each quadrant was compared with retinal nerve fiber layer (RNFL) thickness in their respective quadrants. MAIN OUTCOME MEASURES: Peripapillary choroidal thickness, intraclass coefficient, and Pearson's correlation coefficient. RESULTS: The peripapillary choroid in the inferior quadrant was significantly thinner compared with all other quadrants (P<0.001). None of the other quadrants were significantly different from each other in terms of thickness. The inferior peripapillary choroid was significantly thinner compared with all other quadrants at all distances measured away from the optic nerve (P<0.001). Generally, the peripapillary choroid increases in thickness the farther it was away from the optic nerve and eventually approaching a plateau. The intraclass correlation coefficient ranged from 0.62 to 0.93 and Pearson's correlation coefficient ranged from 0.74 to 0.95 (P<0.001). Neither RNFL thickness nor average age was significantly correlated with average choroidal thickness. CONCLUSIONS: Manual segmentation of the peripapillary choroidal thickness is reproducible between graders, suggesting that this method is accurate. The inferior peripapillary choroid was significantly thinner than all other quadrants (P<0.001). FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Use of Handheld Intraoperative Spectral-Domain Optical Coherence Tomography in a Variety of Vitreoretinal Diseases.

BACKGROUND AND OBJECTIVE: The use of intraoperative optical coherence tomography (iOCT) has been described with a variety of imaging devices and techniques. The purpose of this investigation is to examine the role of iVue (Optovue, Fremont, CA), a commercially available, handheld spectral-domain iOCT system, in vitreoretinal surgery. PATIENTS AND METHODS For this retrospective, observational case series, patients who underwent a vitreoretinal surgical procedure and were imaged with the iVue were identified. Images were qualitatively assessed. RESULTS: Five cases were identified, including an examination under anesthesia, epiretinal membrane, macular hole, retinal detachment, and non-clearing vitreous hemorrhage in the setting of proliferative diabetic retinopathy. CONCLUSION: Clinically useful images were obtained in all cases, though it was difficult to center the scan on the area of interest in the retina. Further work is necessary to improve system design and investigate the ways in which iOCT can aid in vitreoretinal surgery.

Choroidal thickness in older patients with central serous chorioretinopathy.

BACKGROUND: To investigate the choroidal thickness in older patients with central serous chorioretinopathy (CSCR) compared to age-matched normal subjects. METHODS: Fifteen patients (30 eyes) with CSCR, all aged ≥60 years, and 21 age-matched normal subjects (21 eyes) underwent high-definition raster scanning using SD-OCT. Both eyes from CSCR patients were included in the analysis. The eyes in patients with CSCR were divided into two groups: active CSCR (17 eyes) if there was foveal-involving subretinal fluid and inactive contralateral eye group (13 eyes). Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroidal-scleral junction at 500 µm intervals up to 2500 µm temporal and nasal to the fovea (11 locations). RESULTS: The mean age of the patients with CSCR was 68.87 ± 6.83 years (mean ± standard deviation). Reliable measurements of choroidal thickness were obtainable in 70.6 % of eyes examined. The choroid was statistically significantly thicker in eyes with both active CSCR (P < 0.001) and inactive contralateral eyes (P < 0.01) when compared to normal age-matched eyes. The subfoveal choroid was 95 µm (P < 0.01) thicker in eyes with active CSCR (338.05 ± 31.42 µm) compared with normal eyes (243.05 ± 13.39 µm). The subfoveal choroid thickness in the inactive contralateral eyes was numerically greater than normal, and it was not statistically significantly thicker compared to the normal eyes (difference-55.68 µm, P > 0.05). CONCLUSION: Choroid in older patients with active CSCR was thicker than the choroid in age-matched normal eyes. It is important to consider CSCR as a differential diagnosis of serous retinal detachment in elderly patients with thickened choroid and to consider SD-OCT as an imaging modality by which to evaluate the choroidal thickness.

Analysis of short-term change in subfoveal choroidal thickness in eyes with age-related macular degeneration using optical coherence tomography.

BACKGROUND AND OBJECTIVE: To measure the subfoveal choroidal thickness in patients with age-related macular degeneration (AMD) over 6 months. PATIENTS AND METHODS: A retrospective, observational study of patients with AMD followed up for 6 months at the New England Eye Center. Baseline and 6-month follow-up subfoveal choroidal thickness was measured using spectral-domain OCT and compared. RESULTS: For the entire cohort, there was statistically significant thinning of the subfoveal choroidal thickness at 6 months compared to baseline that was driven by the cohort of patients with neovascular AMD (181.2 ± 75 µm to 173.4 ± 63 µm; P = .049). CONCLUSION: There was a statistically significant decrease in subfoveal choroidal thickness observed in this cohort of patients with AMD over 6 months, but it was driven by the subgroup of patients with neovascular age-related macular degeneration.

Quantitative 3D-OCT motion correction with tilt and illumination correction, robust similarity measure and regularization.

Variability in illumination, signal quality, tilt and the amount of motion pose challenges for post-processing based 3D-OCT motion correction algorithms. We present an advanced 3D-OCT motion correction algorithm using image registration and orthogonal raster scan patterns aimed at addressing these challenges. An intensity similarity measure using the pseudo Huber norm and a regularization scheme based on a pseudo L0.5 norm are introduced. A two-stage registration approach was developed. In the first stage, only axial motion and axial tilt are coarsely corrected. This result is then used as the starting point for a second stage full optimization. In preprocessing, a bias field estimation based approach to correct illumination differences in the input volumes is employed. Quantitative evaluation was performed using a large set of data acquired from 73 healthy and glaucomatous eyes using SD-OCT systems. OCT volumes of both the optic nerve head and the macula region acquired with three independent orthogonal volume pairs for each location were used to assess reproducibility. The advanced motion correction algorithm using the techniques presented in this paper was compared to a basic algorithm corresponding to an earlier version and to performing no motion correction. Errors in segmentation-based measures such as layer positions, retinal and nerve fiber thickness, as well as the blood vessel pattern were evaluated. The quantitative results consistently show that reproducibility is improved considerably by using the advanced algorithm, which also significantly outperforms the basic algorithm. The mean of the mean absolute retinal thickness difference over all data was 9.9 um without motion correction, 7.1 um using the basic algorithm and 5.0 um using the advanced algorithm. Similarly, the blood vessel likelihood map error is reduced to 69% of the uncorrected error for the basic and to 47% of the uncorrected error for the advanced algorithm. These results demonstrate that our advanced motion correction algorithm has the potential to improve the reliability of quantitative measurements derived from 3D-OCT data substantially.

Analysis of the morphology and vascular layers of the choroid in retinitis pigmentosa using spectral-domain OCT.

BACKGROUND AND OBJECTIVE: To analyze choroidal morphology and vascular layers in eyes with retinitis pigmentosa (RP) using spectral-domain optical coherence tomography. PATIENTS AND METHODS: Cross-sectional, retrospective analysis of 14 patients (14 eyes) with RP and 33 healthy subjects (33 eyes) who underwent high-definition one-line raster scanning at a single center. Two independent raters evaluated the morphology, thickness, and vascular layers of the choroid in both groups. RESULTS: The choroid had an irregular shape in 11 of 14 eyes (79%) with RP. The thickest point of choroid was not subfoveal as in healthy eyes, and exaggerated nasal thinning of the choroid was observed in nine of 14 eyes (65%) with RP. Mean subfoveal total choroidal thickness and large choroidal vessel layer thickness were significantly lower in eyes with RP (P = .04 and P = .02, respectively) than in healthy eyes. CONCLUSION: Choroidal morphology is altered and an exaggerated thinning of the large choroidal vessel layer is observed in eyes with RP. Further studies involving correlation of disease stage and severity with choroidal changes may provide further insight into the involvement of choroid in RP and other inherited retinal dystrophies.

The role of spectral-domain OCT in the diagnosis and management of neovascular age-related macular degeneration.

Spectral-domain optical coherence tomography (SD-OCT) has emerged as the ancillary examination of choice to assist the diagnosis and management of neovascular age-related macular degeneration (AMD). SD-OCT provides more detailed images of intraretinal, subretinal, and subretinal pigment epithelium fluid when compared to time-domain technology, leading to higher and earlier detection rates of neovascular AMD activity. Improvements in image analysis and acquisition speed make it important for decision-making in the diagnosis and treatment of this disease. However, this new technology needs to be validated for its role in the improvement of visual outcomes in the context of anti-angiogenic therapy.