Retinal imaging using adaptive optics optical coherence tomography with fast and accurate real-time tracking.

One of the main obstacles in high-resolution 3-D retinal imaging is eye motion, which causes blur and distortion artifacts that require extensive post-processing to be corrected. Here, an adaptive optics optical coherence tomography (AOOCT) system with real-time active eye motion correction is presented. Correction of ocular aberrations and of retinal motion is provided by an adaptive optics scanning laser ophthalmoscope (AOSLO) that is optically and electronically combined with the AOOCT system.

Wide-vergence, multi-spectral adaptive optics scanning laser ophthalmoscope with diffraction-limited illumination and collection.

Visualizing and assessing the function of microscopic retinal structures in the human eye is a challenging task that has been greatly facilitated by ophthalmic adaptive optics (AO). Yet, as AO imaging systems advance in functionality by employing multiple spectral channels and larger vergence ranges, achieving optimal resolution and signal-to-noise ratios (SNR) becomes difficult and is often compromised. While current-generation AO retinal imaging systems have demonstrated excellent, near diffraction-limited imaging performance over wide vergence and spectral ranges, a full theoretical and experimental analysis of an AOSLO that includes both the light delivery and collection optics has not been done, and neither has the effects of extending wavefront correction from one wavelength to imaging performance in different spectral channels.

Super-resolution retinal imaging using optically reassigned scanning laser ophthalmoscopy.

Super-resolution optical microscopy techniques have enabled the discovery and visualization of numerous phenomena in physics, chemistry and biology. However, the highest resolution super-resolution techniques depend on nonlinear fluorescence phenomena and are thus inaccessible to the myriad applications that require reflective imaging. One promising super-resolution technique is optical reassignment, which so far has only shown potential for fluorescence imaging at low speeds.

Three-dimensional pattern of extraretinal neovascular development in retinopathy of prematurity.

Background: The application of three-dimensional (3D) visualization techniques to evaluate the earliest visible onset of abnormal retinal vascular development in preterm infants with retinopathy of prematurity (ROP), using bedside non-contact optical coherence tomography (OCT) imaging to characterize morphology and sequential structural changes of abnormal extraretinal neovascularization.

Methods: Thirty-one preterm infants undergoing routine ROP screening with written informed consent for research imaging were enrolled in this prospective observational study. We imaged the macula and temporal periphery of preterm infants using a handheld OCT system (Envisu 2300 or handheld swept-source research system).

Versatile multi-detector scheme for adaptive optics scanning laser ophthalmoscopy.

Adaptive optics scanning laser ophthalmoscopy (AOSLO) is a powerful tool for imaging the retina at high spatial and temporal resolution. In this paper, we present a multi-detector scheme for AOSLO which has two main configurations: pixel reassignment and offset aperture imaging. In this detection scheme, the single element detector of the standard AOSLO is replaced by a fiber bundle which couples the detected light into multiple detectors.

Handheld Adaptive Optics Scanning Laser Ophthalmoscope.

Adaptive optics scanning laser ophthalmoscopy (AOSLO) has enabled in vivo visualization and enhanced understanding of retinal structure and function. Current generation AOSLOs have a large footprint and are mainly limited to imaging cooperative adult subjects. To extend the application of AOSLO to new patient populations, we have designed the first portable handheld AOSLO (HAOSLO) system.

Wide-field retinal optical coherence tomography with wavefront sensorless adaptive optics for enhanced imaging of targeted regions.

The peripheral retina of the human eye offers a unique opportunity for assessment and monitoring of ocular diseases. We have developed a novel wide-field (>70°) optical coherence tomography system (WF-OCT) equipped with wavefront sensorless adaptive optics (WSAO) for enhancing the visualization of smaller (<25°) targeted regions in the peripheral retina. We iterated the WSAO algorithm at the speed of individual OCT B-scans (~20 ms) by using raw spectral interferograms to calculate the optimization metric.

Handheld, rapidly switchable, anterior/posterior segment swept source optical coherence tomography probe.

We describe the first handheld, swept source optical coherence tomography (SSOCT) system capable of imaging both the anterior and posterior segments of the eye in rapid succession. A single 2D microelectromechanical systems (MEMS) scanner was utilized for both imaging modes, and the optical paths for each imaging mode were optimized for their respective application using a combination of commercial and custom optics. The system has a working distance of 26.

True color scanning laser ophthalmoscopy and optical coherence tomography handheld probe.

Scanning laser ophthalmoscopes (SLOs) are able to achieve superior contrast and axial sectioning capability compared to fundus photography. However, SLOs typically use monochromatic illumination and are thus unable to extract color information of the retina. Previous color SLO imaging techniques utilized multiple lasers or narrow band sources for illumination, which allowed for multiple color but not "true color" imaging as done in fundus photography.

Handheld simultaneous scanning laser ophthalmoscopy and optical coherence tomography system.

Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) are widely used retinal imaging modalities that can assist in the diagnosis of retinal pathologies. The combination of SLO and OCT provides a more comprehensive imaging system and a method to register OCT images to produce motion corrected retinal volumes. While high quality, bench-top SLO-OCT systems have been discussed in the literature and are available commercially, there are currently no handheld designs.

Optimization of confocal scanning laser ophthalmoscope design.

Confocal scanning laser ophthalmoscopy (cSLO) enables high-resolution and high-contrast imaging of the retina by employing spatial filtering for scattered light rejection. However, to obtain optimized image quality, one must design the cSLO around scanner technology limitations and minimize the effects of ocular aberrations and imaging artifacts. We describe a cSLO design methodology resulting in a simple, relatively inexpensive, and compact lens-based cSLO design optimized to balance resolution and throughput for a 20-deg field of view (FOV) with minimal imaging artifacts.

Distributed scanning volumetric SDOCT for motion corrected corneal biometry.

We present a method, termed distributed scanning OCT (DSOCT), which reduces the effects of patient motion on corneal biometry utilizing current-generation clinically available spectral domain optical coherence tomography (SDOCT) systems. We first performed a pilot study of the power spectrum of normal patient axial eye motion based on repeated (M-mode) SDOCT. Using DSOCT to reduce the effects of patient motion, we conducted a preliminary patient study comparing the measured anterior and posterior corneal curvatures and the calculated corneal power to both corneal topography and Scheimpflug photography in normal subjects.

Corneal biometry from volumetric SDOCT and comparison with existing clinical modalities.

We present a comparison of corneal biometric values from dense volumetric spectral domain optical coherence tomography (SDOCT) scans to reference values in both phantoms and clinical subjects. We also present a new optically based "keratometric equivalent power" formula for SDOCT that eliminates previously described discrepancies between corneal power form SDOCT and existing clinical modalities. Phantom objects of varying radii of curvature and corneas of normal subjects were imaged with a clinical SDOCT system.

Robust automatic segmentation of corneal layer boundaries in SDOCT images using graph theory and dynamic programming.

Segmentation of anatomical structures in corneal images is crucial for the diagnosis and study of anterior segment diseases. However, manual segmentation is a time-consuming and subjective process. This paper presents an automatic approach for segmenting corneal layer boundaries in Spectral Domain Optical Coherence Tomography images using graph theory and dynamic programming.