Adaptive Optics Imaging Research Articles

Sky coverage assessment for the European ELT: a joint evaluation for MAORY/MICADO and HARMONI

The instruments developed for the upcoming Extremely Large Telescopes (ELTs) will need efficient adaptive optics (AO) systems to correct the effects of the atmospheric turbulence and allow imaging at the highest angular resolution. One of the most important requirements for ELT AO-assisted instruments will be to deliver diffraction-limited images in a significant part of the sky. For that, the instruments will be equipped with laser guide stars (LGSs) providing most of the information required by AO instruments. But even with LGSs, AO systems still require the use of natural guide stars (NGSs) to compensate for image motion (jitter) and some low order aberrations. These NGSs are eventually limiting the fraction of the sky that can be achieved by AO systems, the so-called sky coverage (SC). We first present the SC assessment methods used for high angular resolution monolithic optical and near-infrared integral field spectrograph (HARMONI) and multiconjugate adaptive optics relay/multi-AO imaging camera for deep observations (MAORY/MICADO), that are both instruments for the ELT of the European Southern Observatory (ESO). They are based on a semianalytical description of the main contributors in the AO error budget, allowing for a fast estimation of the residual jitter. As such, these methods are well suited for statistical estimation of the SC on multiple science fields and/or to efficiently explore the system parameter space. We then compute the SC of the two instruments in cosmological fields from the cosmic assembly near-IR deep extragalactic legacy survey catalog. The goal is to provide an insight on the possibilities given by two different types of tomographic AO systems, i.e., laser tomography AO with HARMONI and multiconjugate AO with MAORY, on the same telescope. In particular, we show that HARMONI and MAORY/MICADO are complementary, meaning that the overall SC of ESO’s ELT is much improved for applications common to both systems.

A Close-in Puffy Neptune with Hidden Friends: The Enigma of TOI 620

We present the validation of a transiting low-density exoplanet orbiting the M2.5 dwarf TOI 620 discovered by the NASA Transiting Exoplanet Survey Satellite (TESS) mission. We utilize photometric data from both TESS and ground-based follow-up observations to validate the ephemerides of the 5.09 day transiting signal and vet false-positive scenarios. High-contrast imaging data are used to resolve the stellar host and exclude stellar companions at separations ≳0.″2. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with multiple precision radial velocity (PRV) spectrographs to confirm the planetary nature of the transiting exoplanet. We calculate a 5σ upper limit of M P < 7.1 M ⊕ and ρ P < 0.74 g cm−3, and we identify a nontransiting 17.7 day candidate. We also find evidence for a substellar (1–20 M J ) companion with a projected separation ≲20 au from a combined analysis of Gaia, adaptive optics imaging, and RVs. With the discovery of this outer companion, we carry out a detailed exploration of the possibilities that TOI 620 b might instead be a circum-secondary planet or a pair of eclipsing binary stars orbiting the host in a hierarchical triple system. We find, under scrutiny, that we can exclude both of these scenarios from the multiwavelength transit photometry, thus validating TOI 620 b as a low-density exoplanet transiting the central star in this system. The low density of TOI 620 b makes it one of the most amenable exoplanets for atmospheric characterization, such as with the James Webb Space Telescope and Ariel, validated or confirmed by the TESS mission to date.

SHARP – VIII. J0924+0219 lens mass distribution and time-delay prediction through adaptive-optics imaging

ABSTRACT Strongly lensed quasars can provide measurements of the Hubble constant (H0) independent of any other methods. One of the key ingredients is exquisite high-resolution imaging data, such as Hubble Space Telescope (HST) imaging and adaptive-optics (AO) imaging from ground-based telescopes, which provide strong constraints on the mass distribution of the lensing galaxy. In this work, we expand on the previous analysis of three time-delay lenses with AO imaging (RX J1131−1231, HE 0435−1223, and PG 1115+080), and perform a joint analysis of J0924+0219 by using AO imaging from the Keck telescope, obtained as part of the Strong lensing at High Angular Resolution Program (SHARP) AO effort, with HST imaging to constrain the mass distribution of the lensing galaxy. Under the assumption of a flat Λ cold dark matter (ΛCDM) model with fixed Ωm = 0.3, we show that by marginalizing over two different kinds of mass models (power-law and composite models) and their transformed mass profiles via a mass-sheet transformation, we obtain $\Delta t_{\rm BA}=6.89\substack{+0.8\\-0.7}\, h^{-1}\hat{\sigma }_{v}^{2}$ d, $\Delta t_{\rm CA}=10.7\substack{+1.6\\-1.2}\, h^{-1}\hat{\sigma }_{v}^{2}$ d, and $\Delta t_{\rm DA}=7.70\substack{+1.0\\-0.9}\, h^{-1}\hat{\sigma }_{v}^{2}$ d, where $h=H_{0}/100\,\rm km\, s^{-1}\, Mpc^{-1}$ is the dimensionless Hubble constant and $\hat{\sigma }_{v}=\sigma ^{\rm ob}_{v}/(280\,\rm km\, s^{-1})$ is the scaled dimensionless velocity dispersion. Future measurements of time delays with 10 per cent uncertainty and velocity dispersion with 5 per cent uncertainty would yield a H0 constraint of ∼15 per cent precision.

A Dearth of Close-in Stellar Companions to M-dwarf TESS Objects of Interest

TESS has proven to be a powerful resource for finding planets, including those that orbit the most prevalent stars in our galaxy: M dwarfs. Identification of stellar companions (both bound and unbound) has become a standard component of the transiting planet confirmation process in order to assess the level of light-curve dilution and the possibility of the target being a false positive. Studies of stellar companions have also enabled investigations into stellar multiplicity in planet-hosting systems, which has wide-ranging implications for both exoplanet detection and characterization, as well as for the formation and evolution of planetary systems. Speckle and AO imaging are some of the most efficient and effective tools for revealing close-in stellar companions; we therefore present observations of 58 M-dwarf TOIs obtained using a suite of speckle imagers at the 3.5 m WIYN telescope, the 4.3 m Lowell Discovery Telescope, and the 8.1 m Gemini North and South telescopes. These observations, as well as near-infrared adaptive optics images obtained for a subset (14) of these TOIs, revealed only two close-in stellar companions. Upon surveying the literature, and cross-matching our sample with Gaia, SUPERWIDE, and the catalog from El-Badry et al., we reveal an additional 15 widely separated common proper motion companions. We also evaluate the potential for undetected close-in companions. Taking into consideration the sensitivity of the observations, our findings suggest that the orbital period distribution of stellar companions to planet-hosting M dwarfs is shifted to longer periods compared to the expected distribution for field M dwarfs.

Visualizing retinal cells with adaptive optics imaging modalities using a translational imaging framework.

Adaptive optics reflectance-based retinal imaging has proved a valuable tool for the noninvasive visualization of cells in the living human retina. Many subcellular features that remain at or below the resolution limit of current in vivo techniques may be more easily visualized with the same modalities in an ex vivo setting. While most microscopy techniques provide significantly higher resolution, enabling the visualization of fine cellular detail in ex vivo retinal samples, they do not replicate the reflectance-based imaging modalities of in vivo retinal imaging. Here, we introduce a strategy for imaging ex vivo samples using the same imaging modalities as those used for in vivo retinal imaging, but with increased resolution. We also demonstrate the ability of this approach to perform protein-specific fluorescence imaging and reflectance imaging simultaneously, enabling the visualization of nearly transparent layers of the retina and the classification of cone photoreceptor types.

Impact of Reference Center Choice on Adaptive Optics Imaging Cone Mosaic Analysis.

PurposeFoveal center marking is a key step in retinal image analysis. We investigated the discordance between the adaptive optics (AO) montage center (AMC) and the foveal pit center (FPC) and its implications for cone mosaic analysis using a commercial flood-illumination AO camera.MethodsThirty eyes of 30 individuals (including 15 healthy and 15 patients with rod–cone dystrophy) were included. Spectral-domain optical coherence tomography was used to determine the FPC, and flood-illumination AO imaging was performed with overlapping image frames to create an AO montage. The AMC was determined by averaging the (0,0) coordinates in the four paracentral overlapping AO image frames. Cone mosaic measurements at various retinal eccentricities were compared between corresponding retinal loci relative to the AMC or FPC.ResultsAMCs were located temporally to the FPCs in 14 of 15 eyes in both groups. The average AMC–FPC discordance was 0.85° among healthy controls and 0.33° among patients with rod-cone dystrophy (P < 0.05). The distance of the AMC from the FPC was a significant determinant of the cone density (β estimate = 218 cells/deg2/deg; 95% confidence interval [CI], 107–330; P < 0.001) and inter-cone distance (β estimate = 0.28 arcmin/deg; 95% CI, 0.15–0.40; P < 0.001), after adjustment for age, sex, axial length, spherical equivalent, eccentricity, and disease status.ConclusionsThere is a marked mismatch between the AMC and FPC in healthy eyes that may be modified by disease process such as rod–cone dystrophy. We recommend users of AO imaging systems carefully align the AO montage with a foveal anatomical landmark, such as the FPC, to ensure precise and reproducible localization of the eccentricities and regions of interest for cone mosaic analysis.

3D Imaging with Double-Helix Point Spread Function and Dynamic Aberration Correction Using a Deformable Mirror

Imaging-based measurements through fluctuating phase boundaries such as free water surfaces or droplets have usually a higher uncertainty due to the changing refraction of light at the boundary. In this paper, a novel measurement system is presented for both 3D imaging with only one camera and aberration correction of light propagation through one boundary. 3D imaging is achieved by introducing a Double-Helix Point Spread Function (DH-PSF). The dynamically introduced aberrations of the phase boundary are measured with a Fresnel Guide Star (FGS) and are corrected with a deformable mirror in a closed-loop system with low latency. The measurement system and the adaptive optics image correction were characterized by means of a linear actuator and a demonstration measurement through an oscillating droplet. For the latter, the uncertainty of a reference flow could be lowered by 58 % using adaptive optics. The technique has the potential to measure complex three-dimensional flows that are optically difficult to access without modification of the experimental setup. Possible applications are optimizations of fuel cells for reducing the consumption of fossil energy.

Optimal Differential Astrometry for Multiconjugate Adaptive Optics. I. Astrometric Distortion Mapping using On-sky GeMS Observations of NGC 6723

Abstract The Extremely Large Telescope and the Thirty Meter Telescope will use state of the art multiconjugate adaptive optics (MCAO) systems to obtain the full D 4 advantage that their apertures can provide. However, to reach the full astrometric potential of these facilities for on-sky science requires understanding any residual astrometric distortions from these systems and find ways to measure and eliminate them. In this work, we use Gemini multiconjugate adaptive optic system (GeMS) observations of the core of NGC 6723 to better understand the on-sky astrometric performance of MCAO. We develop new methods to measure the astrometric distortion fields of the observing system, which probe the distortion at the highest possible spatial resolution. We also describe methods for examining the time-variable and static components of the astrometric distortion. When applied to the GeMS Gemini South Adaptive Optics Imager (GSAOI) data, we are able to see the effect of the field rotator at the subpixel level, and we are able to empirically derive the distortion due to the optical design of GeMS/GSAOI. We argue that the resulting distortion maps are a valuable tool to measure and monitor the on-sky astrometric performance of future instrumentation. Our overall astrometry pipeline produces high-quality proper motions with an uncertainty floor of ∼45 μas yr−1. We measure the proper motion dispersion profile of NGC 6723 from a radius of ∼10″ out to ∼1′ based on ∼12,000 stars. We also produce a high-quality optical–near infrared color–magnitude diagram, which clearly shows the extreme horizontal branch and main-sequence knee of this cluster.

Giant Planet Atmospheres: Dynamics and Variability from UV to Near-IR Hubble and Adaptive Optics Imaging

Each of the giant planets, Jupiter, Saturn, Uranus, and Neptune, has been observed by at least one robotic spacecraft mission. However, these missions are infrequent; Uranus and Neptune have only had a single flyby by Voyager 2. The Hubble Space Telescope, particularly the Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) instruments, and large ground-based telescopes with adaptive optics systems have enabled high-spatial-resolution imaging at a higher cadence, and over a longer time, than can be achieved with targeted missions to these worlds. These facilities offer a powerful combination of high spatial resolution, often &lt;0.05”, and broad wavelength coverage, from the ultraviolet through the near infrared, resulting in compelling studies of the clouds, winds, and atmospheric vertical structure. This coverage allows comparisons of atmospheric properties between the planets, as well as in different regions across each planet. Temporal variations in winds, cloud structure, and color over timescales of days to years have been measured for all four planets. With several decades of data already obtained, we can now begin to investigate seasonal influences on dynamics and aerosol properties, despite orbital periods ranging from 12 to 165 years. Future facilities will enable even greater spatial resolution and, combined with our existing long record of data, will continue to advance our understanding of atmospheric evolution on the giant planets.

Comparing Measurements of Vascular Diameter Using Adaptative Optics Imaging and Conventional Fundus Imaging.

The aim of this prospective study was to compare retinal vascular diameter measurements taken from standard fundus images and adaptive optics (AO) images. We analysed retinal images of twenty healthy subjects with 45-degree funduscopic colour photographs (CR-2 Canon fundus camera, Canon™) and adaptive optics (AO) fundus images (rtx1 camera, Imagine Eyes®). Diameters were measured using three software applications: the VAMPIRE (Vessel Assessment and Measurement Platform for Images of the REtina) annotation tool, IVAN (Interactive Vessel ANalyzer) for funduscopic colour photographs, and AO_Detect_Artery™ for AO images. For the arterial diameters, the mean difference between AO_Detect_Artery™ and IVAN was 9.1 µm (−27.4 to 9.2 µm, p = 0.005) and the measurements were significantly correlated (r = 0.79). The mean difference between AO_Detect_Artery™ and VAMPIRE annotation tool was 3.8 µm (−34.4 to 26.8 µm, p = 0.16) and the measurements were poorly correlated (r = 0.12). For the venous diameters, the mean difference between the AO_Detect_Artery™ and IVAN was 3.9 µm (−40.9 to 41.9 µm, p = 0.35) and the measurements were highly correlated (r = 0.83). The mean difference between the AO_Detect_Artery™ and VAMPIRE annotation tool was 0.4 µm (−17.44 to 25.3 µm, p = 0.91) and the correlations were moderate (r = 0.41). We found that the VAMPIRE annotation tool, an entirely manual software, is accurate for the measurement of arterial and venular diameters, but the correlation with AO measurements is poor. On the contrary, IVAN, a semi-automatic software tool, presents slightly greater differences with AO imaging, but the correlation is stronger. Data from arteries should be considered with caution, since IVAN seems to significantly under-estimate arterial diameters.

Phenotype Heterogeneity and the Association Between Visual Acuity and Outer Retinal Structure in a Cohort of Chinese X-Linked Juvenile Retinoschisis Patients

Purpose: X-linked juvenile retinoschisis (XLRS), caused by mutations in the RS1 gene, is an X-linked recessive inherited disease that typically involves both eyes in the first 2 decades of life. Recently, the phenotype heterogeneity of this condition has drawn increasing attention. We reported various phenotypes caused by RS1 gene mutations in eleven patients from ten Chinese families. Methods: Data on the medical history of the patients from ten Han families of central China were collected. Ophthalmic examinations including best-corrected visual acuity (BCVA), fundus photography, ultra-wide-angle sweep source optical coherence tomography (SS-OCT), and electroretinography (ERG) were performed. Adaptive optics (AO) images were acquired to evaluate the cone photoreceptor mosaic when applicable. Venous blood of the probands and their family members was collected, and DNA was subjected to sequencing based on next-generation sequencing with a custom-designed targeted gene panel PS400 for inherited retinal diseases. Validation was performed by Sanger sequencing and cosegregation. Pathogenicity was determined in accordance with the American College of Medical Genetics and Genomics (ACMG) guidelines. Results: Ten RS1 mutations, including eight missense mutations and two terminator mutations, were identified in 10 XLRS families. c.657C > A (p.C219X) was a novel mutation in this cohort. These patients showed a variety of clinical phenotypes, including fovea schisis, bullous retinoschisis, and macular or peripheral atrophy. Fifteen eyes of eight patients exhibited macular retinoschisis, and twelve eyes of seven patients exhibited peripheral retinoschisis. In addition, three patients showed asymmetrical fundus manifestations. Of importance, three patients without macular retinoschisis were misdiagnosed until genetic testing results were obtained. AO showed a decrease in cone density and loss of regularity in the cystic schisis macular of XLRS. Furthermore, the BCVA was associated with the photoreceptor inner segment and outer segment (IS/OS) thickness. Conclusion: With complicated clinical manifestations, a considerable portion of XLRS patients may present various phenotypes. It should be noted that asymmetry in fundus appearance in both eyes could lead to misdiagnosis easily. Thus, genetic testing is crucial for making a final diagnosis in those patients who are suspected of having amblyopia, bilateral or unilateral macular atrophy, or conditions presenting an asymmetric fundus appearance. In addition, the residual cone photoreceptor structure was critical for the maintenance of useful vision.

Flexible refractive and diffractive micro-optical films shaped by fitting aspherical microprofiles with featured aperture and depth and their spatial arrangement for imaging applications

Patterned surface microstructures over a common silicon wafer are constructed by a single-mask ultraviolet (UV) photolithography and a dual-step wet potassium hydroxide etching. Oriented surface contours such as aspherical refractive profiles, diffractive phase steps, or even the composite appearance shaped by combining both refractive and diffractive microprofiles can be accurately predicted and finely configured through computational fitting. This critical operation involves a careful adjustment of the location of silicon microholes with suitable apertures and concave depths so as to outline a needed square microwindow map defined by the single-mask UV photolithography. This approach leads to an aspherical surface or phase steps with required roughness based on a greedy algorithm developed in-house. The obtained micro-optical films can be effectively used to transform common laser beams with a typical Gaussian profile into patterned beams with various complicated wavefronts. The proposed method highlights a low-cost development of adaptive optical imaging by constructing relatively complicated wavefront or objective circumstances for quantitatively evaluating imaging efficiency. The technology should find typical applications in antilaser interference or attack imaging.

High-throughput volumetric adaptive optical imaging using compressed time-reversal matrix

Deep-tissue optical imaging suffers from the reduction of resolving power due to tissue-induced optical aberrations and multiple scattering noise. Reflection matrix approaches recording the maps of backscattered waves for all the possible orthogonal input channels have provided formidable solutions for removing severe aberrations and recovering the ideal diffraction-limited spatial resolution without relying on fluorescence labeling and guide stars. However, measuring the full input–output response of the tissue specimen is time-consuming, making the real-time image acquisition difficult. Here, we present the use of a time-reversal matrix, instead of the reflection matrix, for fast high-resolution volumetric imaging of a mouse brain. The time-reversal matrix reduces two-way problem to one-way problem, which effectively relieves the requirement for the coverage of input channels. Using a newly developed aberration correction algorithm designed for the time-reversal matrix, we demonstrated the correction of complex aberrations using as small as 2% of the complete basis while maintaining the image reconstruction fidelity comparable to the fully sampled reflection matrix. Due to nearly 100-fold reduction in the matrix recording time, we could achieve real-time aberration-correction imaging for a field of view of 40 × 40 µm2 (176 × 176 pixels) at a frame rate of 80 Hz. Furthermore, we demonstrated high-throughput volumetric adaptive optical imaging of a mouse brain by recording a volume of 128 × 128 × 125 µm3 (568 × 568 × 125 voxels) in 3.58 s, correcting tissue aberrations at each and every 1 µm depth section, and visualizing myelinated axons with a lateral resolution of 0.45 µm and an axial resolution of 2 µm.

Dynamical Mass of the Exoplanet Host Star HR 8799

Abstract HR 8799 is a young A5/F0 star hosting four directly imaged giant planets at wide separations (∼16–78 au), which are undergoing orbital motion and have been continuously monitored with adaptive optics imaging since their discovery over a decade ago. We present a dynamical mass of HR 8799 using 130 epochs of relative astrometry of its planets, which include both published measurements and new medium-band 3.1 μm observations that we acquired with NIRC2 at Keck Observatory. For the purpose of measuring the host-star mass, each orbiting planet is treated as a massless particle and is fit with a Keplerian orbit using Markov chain Monte Carlo. We then use a Bayesian framework to combine each independent total mass measurement into a cumulative dynamical mass using all four planets. The dynamical mass of HR 8799 is 1.47 − 0.17 + 0.12 M ⊙ assuming a uniform stellar mass prior, or 1.46 − 0.15 + 0.11 M ⊙ with a weakly informative prior based on spectroscopy. There is a strong covariance between the planets’ eccentricities and the total system mass; when the constraint is limited to low-eccentricity solutions of e &lt; 0.1, which are motivated by dynamical stability, our mass measurement improves to 1.43 − 0.07 + 0.06 M ⊙. Our dynamical mass and other fundamental measured parameters of HR 8799 together with Modules for Experiments in Stellar Astrophysics Isochrones and Stellar Tracks grids yields a bulk metallicity most consistent with [Fe/H] ∼ −0.25–0.00 dex and an age of 10–23 Myr for the system. This implies hot-start masses of 2.7–4.9 M Jup for HR 8799 b and 4.1–7.0 M Jup for HR 8799 c, d, and e, assuming they formed at the same time as the host star.

Resolving the Multiplicity of Exoplanet Host Stars in Gemini/NIRI Data

Abstract The majority of stars have one or more stellar companions. As exoplanets continue to be discovered, it is crucial to examine planetary systems to identify their stellar companions. By observing a change in proper motion, companions can be detected by the acceleration they induce on their host stars. We selected 701 stars from the Hipparcos–Gaia Catalog of Accelerations (HGCA) that have existing adaptive optics imaging data gathered with Gemini/Near InfraRed Imager (NIRI). Of these, we examined 21 stars known to host planet candidates and reduced their archival NIRI data with Gemini’s DRAGONS software. We assessed these systems for companions using the NIRI images as well as Renormalized Unit Weight Error values in Gaia and accelerations in the HGCA. We detected three known visible companions and found two more systems with no visible companions but astrometric measurements indicating likely unresolved companions.

Detection of elliptical components in adaptive optical image of space target

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

High-resolution images of two wiggling stellar jets, MHO 1502 and MHO 2147, obtained with GSAOI+GeMS

Aims. We investigated the possible cause–effect relation between the wiggling shape of two stellar jets, MHO 1502 and MHO 2147, and the potential binarity of the respective driving stars. Methods. We present high-angular-resolution H2 (2.122 μm) and K-band images obtained with the Gemini South Adaptive Optics Imager (GSAOI) and the Gemini Multi-conjugate Adaptive Optics System (GeMS). The profiles of the jets are depicted in detail by the H2 images. We used K-band data to search for potential close companions to the previously suggested exciting sources, and used archive data to investigate these sources and the environments in which the jets are located. We also applied a model to reproduce the wiggling profiles of the jets. Results. MHO 1502 is composed of a chain of knots delineating the wiggling jet, suggesting that the driving source emitted them in an intermittent manner. Our K-band image of the previously proposed exciting star, IRAC 18064, shows two sources separated by ~240 AU, hinting at its binarity. However, as IRAC 18064 is located off the jet axis at ~2064 AU, it is questionable as to whether this source is the true exciting star. Moreover, the orbital model centred on IRAC 18064 suggests a binary companion at a much greater distance (~2200 AU) than the nearby star (at ~240 AU). On the other hand, the orbital model centred on the axis provides the best fits. Nevertheless, the precession model centred on the axis cannot be discarded, despite having larger residuals and χ2. MHO 2147 displays an S-shaped gentle continuous emission in H2. We identify two other jets in the field of MHO 2147: a previously reported quasi-perpendicular jet, MHO 2148, and a third jet adjacent to MHO 2147. The model that best fits the morphology of the MHO 2147 jet and that of its adjacent jet is precession. The exciting source of MHO 2147 may be a triple system.

Longitudinal chromatic aberration compensation method for dual-wavelength retinal imaging adaptive optics systems

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Short-Term Parafoveal Cone Loss Despite Preserved Ellipsoid Zone in Rod Cone Dystrophy.

PurposeRod–cone dystrophy (RCD) is characterized by centripetal loss of rod followed by cone photoreceptors. In this prospective, observational cohort, we used flood-illumination adaptive optics (AO) imaging to investigate parafoveal cone loss in regions with preserved ellipsoid zone (EZ) in patients with RCD.MethodsEight patients with RCD and 10 age-matched healthy controls underwent spectral-domain optical coherence tomography and AO imaging. The RCD cohort underwent a follow-up examination after 6 months. Cone density (CD) and intercone distance (ICD) measurements were performed at 2° temporal from the fovea. Baseline CD and ICD values were compared between the control and patient groups, and longitudinal changes were calculated in the patient group. Residual EZ span in patients was measured in horizontal foveal B-scans.ResultsBetween the control and patient groups, there was no significant difference in the baseline CD (2094 vs. 1750 cells/deg2, respectively; P = 0.09) and ICD (1.46 vs. 1.62 arcmin, respectively; P = 0.08). Mean CD declined by 198 cells/deg2 (−11.3%; P < 0.01), and mean ICD increased by 0.09 arcmin (+5.6%; P = 0.01) at the 6-month follow-up in the patient group. Mean baseline and follow-up residual EZ spans in the six patients with EZ defect were 3189 µm and 3065 µm, respectively (−3.9%; P = 0.08).ConclusionsAO imaging detected significant parafoveal cone loss over 6-month follow-up even in regions with preserved EZ. Further studies to refine AO imaging protocol and validate cone metrics as a structural endpoint in early RCD are warranted.Translational RelevanceCD and ICD may change prior to EZ span shortening in RCD.

Multimodal Imaging of Torpedo Maculopathy With Fluorescence Adaptive Optics Imaging of Individual Retinal Pigmented Epithelial Cells.

Torpedo maculopathy (TM) is a rare congenital defect of the retinal pigment epithelium (RPE). The RPE is often evaluated clinically using fundus autofluorescence (AF), a technique that visualizes RPE structure at the tissue level from the intrinsic AF of RPE fluorophores. TM lesions typically emit little or no AF, but this macroscopic assessment is unable to resolve the RPE cells, leaving the organization of the RPE cell mosaic in TM unknown. We used fluorescence adaptive optics scanning laser ophthalmoscopy (AOSLO) to show here for the first time the microscopic cellular-level structural alterations to the RPE cell mosaic in TM that underlie the tissue-level changes seen in conventional clinical imaging. We evaluated two patients with TM using conventional clinical imaging techniques and adaptive optics (AO) infrared autofluorescence (IRAF) in AOSLO. Confocal AOSLO revealed relatively normal cones outside the TM lesion but altered cone appearance within it and along its margins in both patients. We quantified cone topography and RPE cell morphometry from the fovea to the margin of the lesion in case 1 and found cone density to be within the normal range across the locations imaged. However, RPE morphometric analysis revealed disrupted RPE cells outside the margin of the lesion; the mean RPE cell area was greater than two standard deviations above the normative range up to approximately 1.5 mm from the lesion margin. Similar morphometric changes were seen to individual RPE cells in case 2. Multi-modal imaging with AOSLO reveals that RPE cells are abnormal in TM well beyond the margins of the characteristic TM lesion boundary defined with conventional clinical imaging. Since the TM fovea appears to be fully formed, with normal cone packing, it is possible that the congenital RPE defect in TM occurs relatively late in retinal development. This work demonstrates how cellular level imaging of the RPE can provide new insight into RPE pathologies, particularly for rare conditions such as TM.