Mei Young

Exacerbation of choroidal and retinal pigment epithelial atrophy after anti-vascular endothelial growth factor treatment in neovascular age-related macular degeneration.

Purpose: To study the progression of retinal pigment epithelium (RPE) and choroidal atrophy in patients with neovascular age-related macular degeneration (AMD) and to assess for a possible association with the number and type of anti–vascular endothelial growth factor treatments. Methods: Patients with neovascular AMD and a minimum of 1-year follow-up were reviewed. Fellow eyes with nonneovascular AMD were used as control eyes. Retinal pigment epithelial atrophy area and choroidal thickness were determined using spectral-domain optical coherence tomography. Multivariable regression models were used for statistical analyses. Results: A total of 415 eyes were included in the study, with a mean follow-up of 2.2 years. Eyes with neovascular AMD had greater progression of RPE atrophy and choroidal atrophy compared with those with nonneovascular AMD (P < 0.001). Progression of RPE atrophy and choroidal atrophy was independently associated with the total number of injections of bevacizumab and ranibizumab (all P values ⩽ 0.001). In the subgroup of 84 eyes with neovascular AMD and without RPE atrophy at baseline, only bevacizumab was associated with the progression of RPE atrophy (P = 0.003). This study likely lacked statistical power to detect an association with ranibizumab in this subgroup. Conclusion: Retinal pigment epithelial atrophy and choroidal atrophy in neovascular AMD seem to be exacerbated by anti–vascular endothelial growth factor treatment. Possible differences between bevacizumab and ranibizumab require further investigation.

Real-time high-speed volumetric imaging using compressive sampling optical coherence tomography

Volumetric imaging of the Optic Nerve Head (ONH) morphometry with Optical Coherence Tomography (OCT) requires dense sampling and relatively long acquisition times. Compressive Sampling (CS) is an emerging technique to reduce volume acquisition time with minimal image degradation by sparsely sampling the object and reconstructing the missing data in software. In this report, we demonstrated real-time CS-OCT for volumetric imaging of the ONH using a 1060nm Swept-Source OCT prototype. We also showed that registration and averaging of CS-recovered volumes enhanced visualization of deep structures of the sclera and lamina cribrosa. This work validates CS-OCT as a means for reducing volume acquisition time and for preserving high-resolution in volume-averaged images. Compressive sampling can be integrated into new and existing OCT systems without changes to the optics, requiring only software changes and post-processing of acquired data.

Comparative analysis of repeatability of manual and automated choroidal thickness measurements in nonneovascular age-related macular degeneration.

PURPOSE We compared the reproducibility and mutual agreement of the subfoveal choroidal thickness measurements by expert raters and an automated algorithm in enhanced depth imaging optical coherence tomography (EDI-OCT) images of eyes with nonneovascular age-related macular degeneration (AMD). METHODS We recruited 44 patients with nonneovascular AMD and EDI-OCT images were acquired. Subfoveal choroidal thickness was measured manually by two expert raters and automatically by a graph-cut-based algorithm. Drusen area was measured using the automated software (version 6) of Cirrus SD-OCT. The manual and automated choroidal thickness measurements were compared in reproducibility, mutual agreement, and correlation with drusen area. RESULTS The mean subfoveal choroidal thickness was 246 ± 63 μm for the first rater, 214 ± 68 for the second rater, and 209 ± 53 for the automated algorithm. Intraclass correlation coefficients (ICC) and 95% confidence intervals (CI) were 0.96 (CI 0.94-0.98) between the raters, 0.85 (CI 0.77-0.90) between the first rater and the automated algorithm, and 0.84 (CI 0.75-0.89) between the second rater and the automated algorithm. Repeat scan measurement ICCs were 0.91 (CI 0.86-0.94) for the first rater, 0.96 (CI 0.94-0.97) for the second rater, and 0.87 (CI 0.80-0.92) for the automated algorithm. Manual and automated measurements were correlated with drusen area. CONCLUSIONS The automated algorithm generally yielded smaller choroidal thickness than the raters with a moderate level of agreement. However, its repeat scan measurement repeatability was comparable to that of the manual measurements. The mean difference between the raters indicated possible biases in different raters and rating sessions. The correlation of the automated measurements with the drusen area was comparable to that of the manual measurements. Automated subfoveal choroidal thickness measurement has potential use in clinical practice and clinical trials, with possibility for reduced time and labor cost.

Retinal angiography with real-time speckle variance optical coherence tomography

This report describes a novel, non-invasive and label-free optical imaging technique, speckle variance optical coherence tomography (svOCT), for visualising blood flow within human retinal capillary networks. This imaging system uses a custom-built swept source OCT system operating at a line rate of 100 kHz. Real-time processing and visualisation is implemented on a consumer grade graphics processing unit. To investigate the quality of microvascular detail acquired with this device we compared images of human capillary networks acquired with svOCT and fluorescein angiography. We found that the density of capillary microvasculature acquired with this svOCT device was visibly greater than fluorescein angiography. We also found that this svOCT device had the capacity to generate en face images of distinct capillary networks that are morphologically comparable with previously published histological studies. Finally, we found that this svOCT device has the ability to non-invasively illustrate the common manifestations of diabetic retinopathy and retinal vascular occlusion. The results of this study suggest that graphics processing unit accelerated svOCT has the potential to non-invasively provide useful quantitative information about human retinal capillary networks. Therefore svOCT may have clinical and research applications for the management of retinal microvascular diseases, which are a major cause of visual morbidity worldwide.

Optic Nerve Head and Peripapillary Morphometrics in Myopic Glaucoma

PURPOSE To investigate morphological characteristics of optic nerve head and peripapillary region with myopia and glaucoma. METHODS Ten normal and 17 glaucomatous myopic participants were imaged with a custom 1060-nm swept-source optical coherence tomography system. The three-dimensional images were processed and segmented for inner limiting membrane (ILM), posterior border of retinal nerve fiber layer (RNFL), Bruchs membrane (BM), and posterior border of choroid. Seven shape parameters were measured: nerve fiber layer (NFL) thickness; Bruchs membrane opening (BMO) area, eccentricity, and planarity; BMO and BM depths; and choroidal thickness. The results were analyzed by group and regional sector, and multiple regression was performed on each shape parameter with age, axial length, and glaucoma severity, measured by mean deviation (MD). RESULTS Bruchs membrane opening area (P < 0.001), eccentricity (P = 0.025), and planarity (P = 0.019) were correlated with axial length but not with MD, such that larger, more elliptical, and less planar BMO was associated with longer axial length. Several BMOs displayed a saddle-like shape configuration whose orientation appeared to be aligned with that of the BMO ellipse. All BM showed posterior deformation toward BMO such that BM closer to BMO was more posterior than that farther from BMO. Bruchs membrane depth was correlated with axial length (P = 0.014) and MD (P = 0.040) in intersubject regression, and BMO depth (P = 0.003) and BM depth (P = 0.006) were correlated with MD in intereye regression. Bruchs membrane depth was also associated with age. Choroidal thickness was negatively correlated with age (P = 0.001) and with axial length to a smaller degree (P = 0.034), but not with glaucoma severity. CONCLUSIONS Axial length was a significant factor in BMO and BM shape in normal and glaucomatous myopic subjects. Posterior deformation of BM was observed in all eyes and significantly associated with functional glaucomatous damage and age.

Optical coherence tomography-based measurement of drusen load predicts development of advanced age-related macular degeneration.

PURPOSE To determine whether baseline drusen load, as measured using spectral-domain optical coherence tomography (SD OCT), is a useful predictor of development of advanced age-related macular degeneration (AMD). DESIGN Retrospective cohort study. METHODS setting: Academic clinical practice. study population: All patients with non-neovascular AMD and no retinal pigment epithelial (RPE) atrophy at baseline who were seen between 2007 and 2012 in a single academic retina practice. A minimum of 1 year of follow-up was required. observation: Drusen load (area and volume) was assessed using automated SD OCT software algorithms. main outcome measure: RPE atrophy area, assessed using an automated SD OCT software algorithm, and the development of neovascular AMD. RESULTS Eighty-three patients met the inclusion criteria with a mean age of 80 years and a mean follow-up time of 2.8 years. Repeated-measures analysis of variance showed an association between drusen area (P = .005) and drusen volume (P = .001) and the development of RPE atrophy. We also found an association between drusen area (P = .001) and drusen volume (P = .001) and the development of neovascular AMD. CONCLUSIONS Drusen load, as measured using SD OCT, is associated with the development of RPE atrophy and neovascular AMD. SD OCT assessments of drusen load are simple and practical measurements that may be useful in stratifying the risk of developing advanced AMD. These measurements have potential applications in both routine clinical care and clinical trials.

Optic Nerve Head Registration Via Hemispherical Surface and Volume Registration

We present an automated method for nonrigid registration of the optic nerve head (ONH) surfaces extracted from 3-D optical coherence tomography images to give a one-to-one correspondence between two ONH surfaces. This allows development of population-average ONH surfaces, pooling of morphometric data measured on ONH surfaces from multiple subjects into a single chosen template surface, and statistical analysis (cross sectional, or longitudinal, or both) in a common coordinate system. An application of this coordinate system to construct an average ONH shape across an illustrative dataset is demonstrated, and the impact of template selection is assessed.

Choroidal degeneration in birdshot chorioretinopathy.

Purpose: The purpose of the study was to determine if progressive choroidal changes occur in birdshot chorioretinopathy (BSCR). Methods: Retrospective chart review of all patients with BSCR who were seen over a 3-year period. Controls consisted of healthy age-matched and gender-matched patients. Choroidal thickness at baseline and final follow-up visit was measured with the use of optical coherence tomography. Results were analyzed using univariate and multivariable statistical models. Results: A total of 11 patients (22 eyes) with BSCR were identified. The majority of BSCR eyes (86%) had clinically inactive disease. Follow-up ranged from 2 months to 27 months. Mean age was 55 years. Patients with BSCR had significantly thinner choroid compared with controls (P < 0.001). Furthermore, the rate of choroid thinning for patients diagnosed with BSCR (2.68 &mgr;m per month) was significantly higher than that of controls (0.27 &mgr;m per month) (P = 0.003). There was no statistically significant difference in the rate of choroidal thinning between the two eyes of patients with BSCR (P = 0.859), indicating that the choroidal thinning was symmetrical. Conclusion: Despite having clinically inactive uveitis, eyes with BSCR can develop progressive choroidal thinning. The clinical relevance of this choroidal thinning, or degeneration, remains to be fully elucidated.

Automatic detection of subretinal fluid and sub-retinal pigment epithelium fluid in optical coherence tomography images

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. Subretinal fluid (SRF) and sub-retinal pigment epithelium (sub-RPE) fluid are signs of AMD and can be detected in optical coherence tomography images. However, manual detection and segmentation of SRFs and sub-RPE fluids are laborious and time consuming. In this paper, a novel pipeline is proposed for automatic detection of SRFs and sub-RPE fluids. First, top and bottom layers of retina are segmented using a graph cut method. Then, a Split Bregman-based segmentation method is used to segment dark regions between layers. These segmented regions are considered as potential fluid candidates, on which a set of features are generated. After that, a random forest classifier is trained to distinguish between the true fluid regions from the falsely detected fluid regions. This method shows reasonable performance in a leave-one-out evaluation using a dataset from 21 patients.

Quantitative Assessment of Retinal Degeneration in Birdshot Chorioretinopathy Using Optical Coherence Tomography.

BACKGROUND AND OBJECTIVE Retinal degeneration in birdshot chorioretinopathy (BSCR) has been assessed qualitatively using spectral-domain optical coherence tomography (SD-OCT). The purpose of this study was to determine whether these changes could be quantified. PATIENTS AND METHODS The charts of 22 eyes of 11 patients with BSCR and 22 eyes of 22 controls were reviewed. SD-OCT was used to determine the photoreceptor outer segment (PROS) volume and choroidal thickness. RESULTS PROS volume in patients with BSCR was lower than in controls (P < .003). Furthermore, the PROS volume in BSCR patients with abnormalities on electroretinography (ERG) was lower than the PROS volume in BSCR patients with normal ERGs (P < .02). There was no correlation between PROS volume and choroidal thickness (r = 0.27; P = .22). CONCLUSION SD-OCT can be used to quantitate retinal degeneration in BSCR. The retinal and choroidal degeneration in BSCR are not correlated, suggesting that the inflammatory pathophysiology affecting these two structures may be different.