Intra-Subject Variability and Diurnal Cycle of Ocular Perfusion Pressure as Characterized by Continuous Telemetry in Nonhuman Primates.

Purpose: To characterize ocular perfusion pressure (OPP) fluctuations with continuous telemetry over 24-hour periods across multiple days in nonhuman primates (NHPs) to test the hypotheses that OPP differs among NHPs and that the diurnal cycle of OPP is characterized by low OPP during sleep.

Methods: We have developed and validated two implantable radiotelemetry systems that allow continuous measurement of intraocular pressure (IOP), arterial blood pressure (BP), and OPP up to 500 Hz. OPP was measured unilaterally in 12 male NHPs for periods of 38 to 412 days.

Assessing Retinal Structure in Patients with Parkinson's Disease.

Objective: The retina is an extension of the central nervous system (CNS), and ocular symptoms can precede manifestations of CNS disorders. Given that several neurodegenerative conditions that affect the brain exhibit ocular symptoms, the retina may be an accessible biomarker to monitor disease progression. Dopamine, the key neurotransmitter related to Parkinson's disease (PD), is contained in amacrine and interplexiform cells, which reside in specific retinal layers.

DYNAMISM OF DOT SUBRETINAL DRUSENOID DEPOSITS IN AGE-RELATED MACULAR DEGENERATION DEMONSTRATED WITH ADAPTIVE OPTICS IMAGING.

Purpose: To investigate the natural history of dot subretinal drusenoid deposits (SDD) in age-related macular degeneration, using high-resolution adaptive optics scanning laser ophthalmoscopy.

Methods: Six eyes of four patients with intermediate age-related macular degeneration were studied at baseline and 1 year later. Individual dot SDD within the central 30° retina were examined with adaptive optics scanning laser ophthalmoscopy and optical coherence tomography.

RefMoB, a Reflectivity Feature Model-Based Automated Method for Measuring Four Outer Retinal Hyperreflective Bands in Optical Coherence Tomography.

Purpose: To validate a model-driven method (RefMoB) of automatically describing the four outer retinal hyperreflective bands revealed by spectral-domain optical coherence tomography (SDOCT), for comparison with histology of normal macula; to report thickness and position of bands, particularly band 2 (ellipsoid zone [EZ], commonly called IS/OS).

Methods: Foveal and superior perifoveal scans of seven SDOCT volumes of five individuals aged 28 to 69 years with healthy maculas were used (seven eyes for validation, five eyes for measurement). RefMoB determines band thickness and position by a multistage procedure that models reflectivities as a summation of Gaussians.

Variability in Human Cone Topography Assessed by Adaptive Optics Scanning Laser Ophthalmoscopy.

Purpose: To assess between- and within-individual variability of macular cone topography in the eyes of young adults.

Design: Observational case series.

Methods: Cone photoreceptors in 40 eyes of 20 subjects aged 19-29 years with normal maculae were imaged using a research adaptive optics scanning laser ophthalmoscope.

Outer retinal structure in best vitelliform macular dystrophy.

Importance: Demonstrating the utility of adaptive optics scanning light ophthalmoscopy (AOSLO) to assess outer retinal structure in Best vitelliform macular dystrophy (BVMD).

Objective: To characterize outer retinal structure in BVMD using spectral-domain optical coherence tomography (SD-OCT) and AOSLO.

Design, Setting, And Participants: Prospective, observational case series.

Subclinical macular findings in infants screened for retinopathy of prematurity with spectral-domain optical coherence tomography.

Objective: To evaluate subclinical macular findings in premature patients at risk of retinopathy of prematurity (ROP) with the use of handheld spectral-domain optical coherence tomography (SD-OCT).

Design: Prospective, observational case series.

Participants: Forty-nine prematurely born neonates.

High-resolution images of retinal structure in patients with choroideremia.

Purpose: To study retinal structure in choroideremia patients and carriers using high-resolution imaging techniques.

Methods: Subjects from four families (six female carriers and five affected males) with choroideremia (CHM) were characterized with best-corrected visual acuity (BCVA), kinetic and static perimetry, full-field electroretinography, and fundus autofluorescence (FAF). High-resolution macular images were obtained with adaptive optics scanning laser ophthalmoscopy (AOSLO) and spectral domain optical coherence tomography (SD-OCT).

Evaluation of normal human foveal development using optical coherence tomography and histologic examination.

Objective: To assess outer retinal layer maturation during late gestation and early postnatal life using optical coherence tomography and histologic examination.

Methods: Thirty-nine participants 30 weeks' postmenstrual age or older were imaged using a handheld optical coherence tomography system, for a total of 102 imaging sessions. Foveal images from 16 participants (21 imaging sessions) were normal and evaluated for inner retinal excavation and the presence of outer retinal reflective bands.

Assessing retinal structure in complete congenital stationary night blindness and Oguchi disease.

Purpose: To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease.

Design: Prospective, observational case series.

Methods: We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control.

Imaging the photoreceptor mosaic with adaptive optics: beyond counting cones.

Recent years have seen an explosion in the development of novel ophthalmic imaging devices, delivering non-invasive views of the living retina. Adaptive optics (AO) imaging systems enable resolution of individual cells in the living retina. Analysis of these images has been limited to measures of cone density and regularity.

Assessing the photoreceptor mosaic over drusen using adaptive optics and SD-OCT.

Drusen are extracellular deposits that accumulate between the retinal pigment epithelium and Bruch's membrane. They are one of the earliest clinical manifestations of age-related macular degeneration and it is thought that they disrupt the overlying photoreceptors, leading to subsequent vision loss. The purpose of this study was to illustrate how spectral domain optical coherence tomography and adaptive optics fundus imaging can be used to quantitatively analyze the integrity of the overlying photoreceptors in a single subject with macular drusen.

Adaptive optics retinal imaging: emerging clinical applications.

The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases.

Spectral domain optical coherence tomography and adaptive optics: imaging photoreceptor layer morphology to interpret preclinical phenotypes.

Recent years have seen the emergence of advances in imaging technology that enable in vivo evaluation of the living retina. Two of the more promising techniques, spectral domain optical coherence tomography (SD-OCT) and adaptive optics (AO) fundus imaging provide complementary views of the retinal tissue. SD-OCT devices have high axial resolution, allowing assessment of retinal lamination, while the high lateral resolution of AO allows visualization of individual cells.

Spectral-domain optical coherence tomography and adaptive optics may detect hydroxychloroquine retinal toxicity before symptomatic vision loss.

Purpose: To describe spectral-domain optical coherence tomography (SD-OCT) and adaptive optics (AO) imaging in hydroxychloroquine retinal toxicity.

Methods: Two patients with long-term hydroxychloroquine use, subtle perifoveal ophthalmoscopic pigmentary changes, and bilateral perifoveal defects on automated Humphrey visual field (HVF) 10-2 perimetry were imaged using SD-OCT and AO.

Results: SD-OCT images demonstrated loss of photoreceptor inner segment/outer segment (IS/OS) junction and a downward "sink-hole" displacement of inner retinal structures in areas of hydroxychloroquine toxicity corresponding to HVF 10-2 defects and ophthalmoscopic clinical examination findings.

Variable optical activation of human cone photoreceptors visualized using a short coherence light source.

It has been shown that after a visible stimulus, optical oscillations of nearly all cone photoreceptors can be observed using long coherence length light and in a few cones using short coherence length light. Here, we show that after exposure to a visible stimulus, a short coherence length imaging source reveals light-evoked oscillation signals in a large number of cones. More than 80% of cones in a given retinal area are activated (modulation in the reflectance signal) after stimulation, and the pattern of their activation can be subjectively classified into one of four categories.