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Purpose: To investigate the thickness and variation profiles of 8 intraretinal layers in myopia. Design: Prospective cross-sectional study. Methods: Young subjects with spherical equivalents ranging from +0.50 to -10.25 diopters and good corrected vision were divided into emmetropic (n = 20), low myopic (n = 50), and high myopic (n = 30) groups. Retinal images centered on the fovea along the horizontal and vertical meridians were obtained by ultrahigh-resolution optical coherence tomography (OCT). Macular images were segmented into 8 intraretinal layers by an automatic segmentation algorithm to yield thickness profiles within a 6-mm-diameter circle divided into central, pericentral, and peripheral regions. Results: For intraretinal layers in the central region, the outer segment of receptors layer was thicker in the high myopic group and positively correlated with axial length. In the pericentral and peripheral regions, all layers except the ganglion cell and inner plexiform layer had thickness changes in high myopia. The total thickness of the peripheral region was less than in the emmetropic controls owing to thinner inner nuclear layer, combined Henle fiber and outer nuclear layer, and outer segment of receptors layer. Nevertheless, the thicknesses of the combined myoid and ellipsoid zone and the combined interdigitation zone and retinal pigment epithelium/Bruch complex in the peripheral region were greater than for the emmetropic controls. Conclusions: Intraretinal layer thicknesses in young high myopic eyes varied significantly from emmetropic controls, especially in the peripheral region. Ultrahigh-resolution OCT with automated segmentation can detect changes in retinal macular microstructure during the development of myopia. [ABSTRACT FROM AUTHOR]

Radiation-associated toxicities due to sophisticated ocular anatomy and shape variability of organs at risk (OARs) are major concerns during external beam radiation therapy (EBRT) of patients with intraocular cancer. A novel two-step image registration strategy between optical coherence tomography (OCT) and computed tomography (CT) images was proposed and validated to precisely localize the target in the EBRT of patients with intraocular cancer. Specifically, multiple features from OCT and CT images were extracted automatically, then spatial transformation based on thin-plate spline function was performed iteratively to achieve feature alignment between the CT and OCT images. Finally, an exclusive OR (XOR) algorithm was applied for precise 3D registration using a 3D-mesh model generated from OCT and CT volumes. The accuracy of the proposed novel registration strategy was validated and tested in a schematic-eye phantom with an artificially introduced tumor and in ten patients with confirmed primary and/or secondary intraocular cancer. There was an average registration error and computational time of 0.21  ±  0.05° and 259  ±  5 s, together with an average Dice similarity coefficient and Hausdorff distance of 88.4  ±  0.65 and 0.89  ±  0.09, respectively. The preliminary experimental results demonstrated that the proposed novel strategy to overcome current limitations on eye modeling and to localize precisely the tumor target during EBRT of intraocular cancer is promising. [ABSTRACT FROM AUTHOR]

Corneal collagen cross-linking (CXL) strengthens the biomechanical properties of damaged corneas. Quantifying the changes of stiffness due to different CXL protocols is difficult, especially in vivo. A noninvasive elastic wave-based optical coherence elastography system was developed to construct in vivo corneal elasticity maps by excitation of air puff. Biomechanical differences were compared for rabbit corneas given three different CXL protocols while keeping the total energy delivered constant. The Young's modulus was weaker in corneas treated with higher irradiance levels over shorter durations, and a slight increase of Young's modulus was present in all groups one week after the recovery process. Due to the noninvasive nature and minimal force to generate corneal elastic waves, this technique has the potential for early detection and treatment of corneal diseases in clinic. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to investigate the repeatability of retinal oximetry using slit-lamp adapted ultrahigh-resolution optical coherence tomography (SL-UHR-OCT). Methods: SL-UHR-OCT was developed and fringe patterns were obtained for a major retinal artery and a major retinal vein. A-scans at the central wavelengths of 805 nm and 855 nm were analyzed for calculating optical density ratios (ODRs), from which the percentage oxygen saturation was calculated. Measurements were made on two occasions for each person. Repeatability and coefficients of repeatability were calculated. Results: The mean ODRs of the artery were 0.79 ± 0.86 and 0.88 ± 0.97 in sessions 1 and 2, respectively. The mean ODRs of the vein were -0.08 ± 0.69 and 0.14 ± 0.77 between the two sessions, and were significantly lower than that of the artery (P < 0.05). The coefficients of repeatability were 1.44 and 1.81 for the artery and vein, respectively. The mean oxygen saturation of the major retinal artery was 94% ± 45% and 98% ± 51% in sessions 1 and 2, respectively, and the mean oxygen saturation of the major retinal vein was 48% ± 36% and 60% ± 40% between sessions. Conclusion: Optical coherence tomographic oximetry for evaluating retinal oxygen saturation was subject to variation, although the averaged measurements in repeated sessions were matched. Further work on reducing variation will be needed. [ABSTRACT FROM AUTHOR]

Purpose: This study was designed to determine the ability of ultra-high-resolution optical coherence tomography (UHR-OCT) to monitor tear meniscus volume after dry eye treatment with Restasis® (0.05% cyclosporine). Methods: UHR-OCT was used to image the upper and lower tear menisci (height and volume) in 14 consecutive dry eye patients at baseline. The treatment group was initiated on daily Restasis and measurements were repeated at 1 and 2 months while on treatment. All measurements were performed immediately after a blink. Results: The baseline tear meniscus volumes were 0.40 ± 0.19 μL (upper) and 0.43 ± 0.18 μL (lower). In the treatment group, tear meniscus heights showed significant increases of both upper (post-hoc test with Bonferroni correction: P = 0.003) and lower (P = 0.0003) tear menisci, after 1 month on Restasis. The tear meniscus volumes in the treatment group after 1 month of Restasis showed significant increases of both upper (P = 0.007) and lower (P = 0.007) tear menisci. At 2 months, the increase of the tear meniscus was still evident in all measured variables compared with baseline (P < 0.05). Conclusion: UHR-OCT offers a promising tool for monitoring dry eye treatment. With this method, a measurable increase in tear meniscus volume was evident after 1 month of treatment with Restasis in dry eye patients. [ABSTRACT FROM AUTHOR]

The etiology of the highly myopic condition has been unclear for decades. We investigated the genetic contributions to early-onset high myopia (EOHM), which is defined as having a refraction of less than or equal to -6 diopters before the age of 6, when children are less likely to be exposed to high educational pressures. Trios (two nonmyopic parents and one child) were examined to uncover pathogenic mutations using whole-exome sequencing. We identified parent-transmitted biallelic mutations or de novo mutations in asyet-unknown or reported genes in 16 probands. Interestingly, an increased rate of de novo mutations was identified in the EOHM patients. Among the newly identified candidate genes, a BSG mutation was identified in one EOHM proband. Expanded screening of 1,040 patients found an additional four mutations in the same gene. Then, we generated Bsg mutant mice to further elucidate the functional impact of this gene and observed typical myopic phenotypes, including an elongated axial length. Using a trio-based exonic screening study in EOHM, we deciphered a prominent role for de novo mutations in EOHM patients without myopic parents. The discovery of a disease gene, BSG, provides insights into myopic development and its etiology, which expands our current understanding of high myopia and might be useful for future treatment and prevention. [ABSTRACT FROM AUTHOR]

Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 μm. Tear films in human eyes, with and without a contact lens, have also been evaluated. A high-contrast spectral reflectance signal from the precontact lens tear film is clearly observed, and the thinning dynamics have been easily recorded from 3.69 to 1.31 μm with lipid layer thickness variation in the range of 41 to 67 nm. The accuracy of the measurement is better than ±0.58% of the film thickness at an estimated tear film refractive index error of ±0.001. The fiber-based reflectometer system is compact and easy to handle. [ABSTRACT FROM AUTHOR]

We demonstrate quantitative analysis and error correction of optical coherence tomography (OCT) retinal images by using a custom-built, computer-aided grading methodology. A total of 60 Stratus OCT (Carl Zeiss Meditec, Dublin, California) B-scans collected from ten normal healthy eyes are analyzed by two independent graders. The average retinal thickness per macular region is compared with the automated Stratus OCT results. Intergrader and intragrader reproducibility is calculated by Bland-Altman plots of the mean difference between both gradings and by Pearson correlation coefficients. In addition, the correlation between Stratus OCT and our methodology-derived thickness is also presented. The mean thickness difference between Stratus OCT and our methodology is 6.53 mand 26.71 mwhen using the inner segment/outer segment (IS/OS) junction and outer segment/retinal pigment epithelium (OS/RPE) junction as the outer retinal border, respectively. Overall, the median of the thickness differences as a percentage of the mean thickness is less than 1 and 2 for the intragrader and intergrader reproducibility test, respectively. The measurement accuracy range of the OCT retinal image analysis (OCTRIMA) algorithm is between 0.27 and 1.47 mand 0.6 and 1.76 mfor the intragrader and intergrader reproducibility tests, respectively. Pearson correlation coefficients demonstrate R20.98for all Early Treatment Diabetic Retinopathy Study (ETDRS) regions. Our methodology facilitates a more robust and localized quantification of the retinal structure in normal healthy controls and patients with clinically significant intraretinal features. [ABSTRACT FROM AUTHOR]