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Background/AimsPrior studies support an association between increased retinal venule diameter and elevated intracranial pressure (ICP). The purpose of this study was to test the hypothesis that retinal venule diameters decrease in association with long-term therapy for high ICP in subjects with idiopathic intracranial hypertension (IIH).MethodsThis is a retrospective analysis of multicentre randomised controlled trial data. Standardised procedures were used to measure area of optic nerve head elevation (ONHA) and diameters of 4 arterioles and 4 venules 2.7 mm from the optic disc centre on fundus photos collected at baseline and after 6 months of randomised treatment with placebo+diet or acetazolamide+diet in subjects participating in the IIH Treatment Trial (IIHTT) (n=115). Change in arteriole (Da) and venule (Dv) diameters from baseline to 6 months was studied as a function of IIH, haemodynamic and demographic variables.ResultsDv decreased following 6 months of therapy (8.1 µm, 5.9%, pConclusionsRetinal venule diameter decreased, and arteriole diameter did not change in association with treatment for elevated ICP with a weight loss intervention and placebo or acetazolamide in IIHTT participants. Further study is needed to determine how retinal vessel measurements can be combined with other clinical observations to inform disease management.

All retina-based vision restoration approaches rely on the assumption that photoreceptor loss does not preclude reactivation of the remaining retinal architecture. Whether extended periods of vision loss limit the efficacy of restorative therapies at the retinal level is unknown. We examined long-term changes in optogenetic responsivity of foveal retinal ganglion cells (RGCs) in non-human primates following localized photoreceptor ablation by high intensity laser exposure. By performing fluorescence adaptive optics scanning light ophthalmoscopy (AOSLO) of RGCs expressing both the calcium indicator GCaMP6s and the optogenetic actuator ChrimsonR, it was possible to track optogenetic mediated calcium responses in deafferented RGCs over time. Fluorescence fundus photography revealed a 40% reduction in ChrimsonR fluorescence in RGCs lacking photoreceptor input over the three weeks following photoreceptor ablation. Despite this, in vivo imaging revealed good cellular preservation of RGCs 3 months after the loss of photoreceptor input, and histology confirmed good structural preservation at 2 years. Optogenetic responses of RGCs in primate persisted for at least one year after the loss of photoreceptor input, with a sensitivity index similar to optogenetic responses recorded in intact retina. These results are promising for all potential therapeutic approaches to vision restoration that rely on preservation and reactivation of RGCs.

Optogenetic therapies for vision restoration aim to confer intrinsic light sensitivity to retinal ganglion cells when photoreceptors have degenerated and light sensitivity has been irreversibly lost. We combine adaptive optics ophthalmoscopy with calcium imaging to optically record optogenetically restored retinal ganglion cell activity in the fovea of the living primate. Recording from the intact eye of a living animal, we compare the patterns of activity evoked by the optogenetic actuator ChrimsonR with natural photoreceptor mediated stimulation in the same retinal ganglion cells. Optogenetic responses are recorded more than one year following administration of the therapy and two weeks after acute loss of photoreceptor input in the living animal. This in vivo imaging approach could be paired with any therapy to minimize the number of primates required to evaluate restored activity on the retinal level, while maximizing translational benefit by using an appropriate pre-clinical model of the human visual system., Non-human primate models are important for the development of high quality vision restoration therapies for blindness. Here, the authors demonstrate restoration of light responses in foveal retinal ganglion cells of the living macaque following optogenetic gene therapy.

Although imaging of the living retina with adaptive optics scanning light ophthalmoscopy (AOSLO) provides microscopic access to individual cells, such as photoreceptors, retinal pigment epithelial cells, and blood cells in the retinal vasculature, other important cell classes, such as retinal ganglion cells, have proven much more challenging to image. The near transparency of inner retinal cells is advantageous for vision, as light must pass through them to reach the photoreceptors, but it has prevented them from being directly imaged in vivo. Here we show that the individual somas of neurons within the retinal ganglion cell (RGC) layer can be imaged with a modification of confocal AOSLO, in both monkeys and humans. Human images of RGC layer neurons did not match the quality of monkey images for several reasons, including safety concerns that limited the light levels permissible for human imaging. We also show that the same technique applied to the photoreceptor layer can resolve ambiguity about cone survival in age-related macular degeneration. The capability to noninvasively image RGC layer neurons in the living eye may one day allow for a better understanding of diseases, such as glaucoma, and accelerate the development of therapeutic strategies that aim to protect these cells. This method may also prove useful for imaging other structures, such as neurons in the brain.

Progress is needed in developing animal models of photoreceptor degeneration and evaluating such models with longitudinal, noninvasive techniques. We employ confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT) and high-resolution retinal imaging to noninvasively observe the retina of non-human primates with induced photoreceptor degeneration. Photoreceptors were imaged at the single-cell scale in three modalities of adaptive optics scanning light ophthalmoscopy: traditional confocal reflectance, indicative of waveguiding; a non-confocal offset aperture technique visualizing scattered light; and two-photon excited fluorescence, the time-varying signal of which, at 730 nm excitation, is representative of visual cycle function. Assessment of photoreceptor structure and function using these imaging modalities revealed a reduction in retinoid production in cone photoreceptor outer segments while inner segments appeared to remain present. Histology of one retina confirmed loss of outer segments and the presence of intact inner segments. This unique combination of imaging modalities can provide essential, clinically-relevant information on both the structural integrity and function of photoreceptors to not only validate models of photoreceptor degeneration but potentially evaluate the efficacy of future cell and gene-based therapies for vision restoration.

PURPOSE: To compare measurements of papilledema using fundus photography, optical coherence tomography (OCT), and Frisén score in patients with idiopathic intracranial hypertension (IIH). DESIGN: Retrospective, non-comparative analysis of RCT data. METHODS: The Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) evaluated weight-management and treatment with acetazolamide compared with placebo in patients with IIH and mild visual loss. Among the 126 subjects in the IIHTT OCT sub-study, fundus photographs and OCT scans of the optic disc were taken at baseline and at 6 and 12 months after enrollment. Trained readers scored each eye using a modified Frisén scale and measured the area of disc elevation. OCT scans assessed optic nerve head (ONH) volume. Correlations between volume and area were computed for both study and non-study eyes. RESULTS: Disc area and ONH volume were positively correlated at baseline (R(2)=0.77 in study eyes, p

Insertion of light-gated channels into inner retina neurons restores neural light responses, light evoked potentials, visual optomotor responses and visually-guided maze behavior in mice blinded by retinal degeneration. This method of vision restoration bypasses damaged outer retina, providing stimulation directly to retinal ganglion cells in inner retina. The approach is similar to that of electronic visual protheses, but may offer some advantages, such as avoidance of complex surgery and direct targeting of many thousands of neurons. However, the promise of this technique for restoring human vision remains uncertain because rodent animal models, in which it has been largely developed, are not ideal for evaluating visual perception. On the other hand, psychophysical vision studies in macaque can be used to evaluate different approaches to vision restoration in humans. Furthermore, it has not been possible to test vision restoration in macaques, the optimal model for human-like vision, because there has been no macaque model of outer retina degeneration. In this study, we describe development of a macaque model of photoreceptor degeneration that can in future studies be used to test restoration of perception by visual prostheses. Our results show that perceptual deficits caused by focal light damage are restricted to locations at which photoreceptors are damaged, that optical coherence tomography (OCT) can be used to track such lesions, and that adaptive optics retinal imaging, which we recently used for in vivo recording of ganglion cell function, can be used in future studies to examine these lesions.

PURPOSE Identify a reproducible measure of axial globe position (AGP) for multicenter studies on patients with thyroid eye disease (TED). METHODS This is a prospective, international, multicenter, observational study in which 3 types of AGP evaluation were examined: radiologic, clinical, and photographic. In this study, CT was the modality to which all other methods were compared. CT AGP was measured from an orthogonal line between the anterior lateral orbital rims to the cornea. All CT measurements were made at a single institution by 3 individual clinicians. Clinical evaluation was performed with exophthalmometry. Three clinicians from each clinical site assessed AGP with 3 different exophthalmometers and horizontal palpebral width using a ruler. Each physician made 3 separate measurements with each type of exophthalmometer not in succession. All photographic measurements were made at a single institution. AGP was measured from lateral photographs in which a standard marker was placed at the anterior lateral orbital rim. Horizontal and vertical palpebral fissure were measured from frontal photographs. Three trained readers measured 3 separate times not in succession. Exophthalmometry and photography method validity was assessed by agreement with CT (mean differences calculation, intraclass correlation coefficients [ICCs], Bland-Altman figures). Correlation between palpebral fissure and CT AGP was assessed with Pearson correlation. Intraclinician and interclinician reliability was evaluated using ICCs. RESULTS Sixty-eight patients from 7 centers participated. CT mean AGP was 21.37 mm (15.96-28.90 mm) right and 21.22 mm (15.87-28.70 mm) left (ICC 0.996 and 0.995). Exophthalmometry AGP fell between 18 mm and 25 mm. Intraclinician agreement across exophthalmometers was ideal (ICC 0.948-0.983). Agreement between clinicians was greater than 0.85 for all upright exophthalmometry measurements. Photographic mean AGP was 20.47 mm (10.92-30.88 mm) right and 20.30 mm (8.61-28.72 mm) left. Intrareader and interreader agreement was ideal (ICC 0.991-0.989). All exophthalmometers' mean differences from CT ranged between -0.06 mm (±1.36 mm) and 0.54 mm (±1.61 mm); 95% confidence interval fell within 1 mm. Magnitude of AGP did not affect exophthalmometry validity. Oculus best estimated CT AGP but differences from other exophthalmometers were not clinically meaningful in upright measurements. Photographic AGP (right ICC = 0.575, left ICC = 0.355) and palpebral fissure do not agree with CT. CONCLUSIONS Upright clinical exophthalmometry accurately estimates CT AGP in TED. AGP measurement was reliably reproduced by the same clinician and between clinicians at multiple institutions using the protocol in this study. These findings allow reliable measurement of AGP that will be of considerable value in future outcome studies.

Posttraumatic iris implantation cysts are rare ocular findings that are often associated with poor visual outcomes. Iris implantation cysts can present clinicians with diagnostic and therapeutic challenges given their variable presentations and frequently destructive nature. In this paper, we provide descriptions of two unusual cases of posttraumatic iris implantation cysts. The first case is of a recurrent keratin-filled iris implantation cyst that developed after open globe injury and intraocular implantation of cilia and was treated with cyst debulking procedures, injections of 5-Fluorouracil, and iridocyclectomy. The second case is of recurrent posttraumatic serous iris implantation cysts that were treated with laser, cyst aspiration, and injections of 5-Fluorouracil. We use these cases as a platform to discuss the different manifestations of implantation cysts, the roles of anterior segment optical coherence tomography, ultrasound biomicroscopy, and histopathology in facilitating timely and accurate diagnosis and review the range of available therapeutic modalities. We discuss conservative treatment approaches, including the novel use of 5-Fluorouracil therapy as an adjunct therapy, as well as more aggressive surgical excision requiring ocular reconstruction. Through a discussion of these cases and review of the literature, we provide recommendations to assist clinicians in managing this uncommon but vision-threatening condition and minimizing complications.

Two-photon ophthalmoscopy has potential for in vivo assessment of function of normal and diseased retina. However, light safety of the sub-100 fs laser typically used is a major concern and safety standards are not well established. To test the feasibility of safe in vivo two-photon excitation fluorescence (TPEF) imaging of photoreceptors in humans, we examined the effects of ultrashort pulsed light and the required light levels with a variety of clinical and high resolution imaging methods in macaques. The only measure that revealed a significant effect due to exposure to pulsed light within existing safety standards was infrared autofluorescence (IRAF) intensity. No other structural or functional alterations were detected by other imaging techniques for any of the exposures. Photoreceptors and retinal pigment epithelium appeared normal in adaptive optics images. No effect of repeated exposures on TPEF time course was detected, suggesting that visual cycle function was maintained. If IRAF reduction is hazardous, it is the only hurdle to applying two-photon retinal imaging in humans. To date, no harmful effects of IRAF reduction have been detected.

Optical coherence tomography (OCT) provides high-resolution views of the macula and enables quantitative assessment of macular thickness.1 Spectral-domain (SD) OCT systems, with faster imaging speed and better resolution than time-domain systems, have increased the utility of this technology for assessing macular thickness. Of paramount importance to the sensitivity and accuracy of these devices for diagnosing macular disease is comparison against a normative database. Although there is well-known racial variability in the susceptibility to retinal diseases such as retinopathy of prematurity,2 age-related macular degeneration (AMD),3,4 and glaucoma,5 widespread acceptance and use of normative databases that control for race- or sex-related differences in retinal anatomy (macula or optic nerve) are currently lacking. This deficit may be due in part to a lack of understanding of the etiology of the racial differences in retinal anatomy. Using a retinal thickness analyzer, Asrani et al.6 first reported differences in retinal thickness between the sexes and races, with black women having the thinnest retinas. As summarized in Table 1, in subsequent studies, OCT has been used to characterize sex- and race-based differences in retinal thickness.7–13 Asefzadeh et al.8 used time-domain OCT and observed significantly thinner total foveal and total macular thickness in African Americans compared with age-matched Caucasians in a small sample (n = 14). This finding was replicated, also with time–domain OCT, in two larger studies that found the mean foveal thicknesses in African Americans to be significantly thinner than in Caucasians.9,12 Interestingly, a study in which SD-OCT was used found no sex-related difference in central macular thickness.11 A second SD-OCT study also found no difference between the sexes in retinal thickness, but did report a significant reduction in retinal thickness in African Americans compared with Caucasians.10 A more recent SD-OCT study of 198 subjects showed that women had significantly thinner retinas than did men.13 Understanding possible race- and sex-associated differences and the mechanism leading to such differences could significantly enhance the interpretation of OCT measurements of retinal thickness. Table 1. Summary of Previous OCT Studies on Racial and Sex Differences in Retinal Thickness Recently, we developed an automated technique to quantify the morphology of the foveal pit (depth, diameter, and slope), and observed significant variation in all three parameters.17 The purpose of the present study was to examine the differences in foveal pit morphology between the sexes and races and their relationship to differences in retinal thickness. Our data indicate that retinal thickness alone is an inadequate explanation of the mechanisms behind observed race- and sex-based differences in retinal thickness. Rather, foveal morphology and retinal thickness together provide a more complete picture of foveal anatomy and should be used in tandem to construct race- and sex-based normative databases.

PURPOSE To describe the methods used by the Photographic Reading Center (PRC) of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) and to report baseline assessments of papilledema severity in participants. METHODS Stereoscopic digital images centered on the optic disc and the macula were collected using certified personnel and photographic equipment. Certification of the camera system included standardization and calibration using a model eye. Lay readers assessed disc photos of all eyes using the Frisen grade and performed quantitative measurements of papilledema. Frisen grades by PRC were compared with site investigator clinical grades. Spearman rank correlations were used to quantify associations among disc features and selected clinical variables. RESULTS Frisen grades according to the PRC and site investigator's grades, matched exactly in 48% of the study eyes and 42% of the fellow eyes and within one grade in 94% of the study eyes and 92% of the fellow eyes. Frisen grade was strongly correlated (r > 0.65, P < 0.0001) with quantitative measures of disc area. Cerebrospinal fluid pressure was weakly associated with Frisen grade and disc area determinations (r ≤ 0.31). Neither Frisen grade nor any fundus feature was associated with perimetric mean deviation. CONCLUSIONS In a prospective clinical trial, lay readers agreed reasonably well with physicians in assessing Frisen grade. Standardization of camera systems enhanced consistency of photographic quality across study sites. Images were affected more by sensors with poor dynamic range than by poor resolution. Frisen grade is highly correlated with quantitative assessment of disc area. (ClinicalTrials.gov number, NCT01003639.).

Many retinal imaging instruments use infrared wavelengths to reduce the risk of light damage. However, we have discovered that exposure to infrared illumination causes a long-lasting reduction in infrared autofluorescence (IRAF). We have characterized the dependence of this effect on radiant exposure and investigated its origin.A scanning laser ophthalmoscope was used to obtain IRAF images from two macaques before and after exposure to 790-nm light (15-450 J/cm(2)). Exposures were performed with either raster-scanning or uniform illumination. Infrared autofluorescence images also were obtained in two humans exposed to 790-nm light in a separate study. Humans were assessed with direct ophthalmoscopy, Goldmann visual fields, multifocal ERG, and photopic microperimetry to determine whether these measures revealed any effects in the exposed locations.A significant decrease in IRAF after exposure to infrared light was seen in both monkeys and humans. In monkeys, the magnitude of this reduction increased with retinal radiant exposure. Partial recovery was seen at 1 month, with full recovery within 21 months. Consistent with a photochemical origin, IRAF decreases caused by either raster-scanning or uniform illumination were not significantly different. We were unable to detect any effect of the light exposure with any measure other than IRAF imaging. We cannot exclude the possibility that changes could be detected with more sensitive tests or longer follow-up.This long-lasting effect of infrared illumination in both humans and monkeys occurs at exposure levels four to five times below current safety limits. The photochemical basis for this phenomenon remains unknown.

Morgan and colleagues demonstrated that the RPE cell mosaic can be resolved in the living human eye non-invasively by imaging the short-wavelength autofluorescence using an adaptive optics (AO) ophthalmoscope. This method, based on the assumption that all subjects have the same longitudinal chromatic aberration (LCA) correction, has proved difficult to use in diseased eyes, and in particular those affected by age-related macular degeneration (AMD). In this work, we improve Morgan's method by accounting for chromatic aberration variations by optimizing the confocal aperture axial and transverse placement through an automated iterative maximization of image intensity. The increase in image intensity after algorithmic aperture placement varied depending upon patient and aperture position prior to optimization but increases as large as a factor of 10 were observed. When using a confocal aperture of 3.4 Airy disks in diameter, images were obtained using retinal radiant exposures of less than 2.44 J/cm(2), which is ~22 times below the current ANSI maximum permissible exposure. RPE cell morphologies that were strikingly similar to those seen in postmortem histological studies were observed in AMD eyes, even in areas where the pattern of fluorescence appeared normal in commercial fundus autofluorescence (FAF) images. This new method can be used to study RPE morphology in AMD and other diseases, providing a powerful tool for understanding disease pathogenesis and progression, and offering a new means to assess the efficacy of treatments designed to restore RPE health.