Retinal safety evaluation of two-photon laser scanning in rats.

Safe use of retinal imaging with two-photon excitation in human eyes is crucial, as the effects of ultrashort pulsed lasers on the retina are relatively unknown. At the time of the study, the laser safety standards were inadequate due to the lack of biological data. This article addresses the feasibility of two-photon retinal imaging with respect to laser safety. In this study, rat retinas were evaluated at various laser exposure levels and with different laser parameters to determine the effects of laser-induced optical damage. The results were experimentally verified using confocal reflectance imaging, two-photon fluorescein angiography, immunohistochemistry, and correlated to the IEC 60825-1 laser safety standard.

In vivo two-photon imaging of retina in rabbits and rats.

The purpose of this study was to evaluate the retina using near-infrared (NIR) two-photon scanning laser ophthalmoscopy. New Zealand white rabbits, albino rats, and brown Norway rats were used in this study. An autofluorescence image of the retina, including the retinal cells and its associated vasculatures was obtained by a real-time scan using the ophthalmoscope. Furthermore, the retinal vessels, nerve fiber layers and the non-pigmented retina were recorded with two-photon fluorescein angiography (FA); and the choroidal vasculatures were recorded using two-photon indocyanine green angiography (ICGA). Two-photon ICGA was achieved by exciting a second singlet state at ∼398 nm. Simultaneous two-photon FA and two-photon ICGA were performed to characterize the retinal and choroidal vessels with a single injection. The minimum laser power threshold required to elicit two-photon fluorescence was determined. The two-photon ophthalmoscope could serve as a promising tool to detect and monitor the disease progression in animal models. Moreover, these high-resolution images of retinal and choroidal vessels can be acquired in a real-time scan with a single light source, requiring no additional filters for FA or ICGA. The combination of FA and ICGA using the two-photon ophthalmoscope will help researchers to characterize the retinal diseases in animal models, and also to classify the types (classic, occult or mixed) of choroidal neovascularization (CNV) in macular degeneration. Furthermore, the prototype can be adapted to image the retina of rodents and rabbits.

EFFECT OF PLASMAPHERESIS AND PASSAGE OF ANTI-RETINAL ANTIBODIES THROUGH THE PLACENTA IN A CASE OF NON-PARANEOPLASTIC AUTOIMMUNE RETINOPATHY.

PURPOSE: To present a case of nonparaneoplastic autoimmune retinopathy in association with myasthenia gravis in a young woman, and to report the effect of plasmapheresis as well as passage of antiretinal antibodies through the placenta. METHODS: Case report. RESULTS: A 31-year-old woman presented with a history of myasthenia gravis and rapidly progressive vision loss at the age of 23. Funduscopic appearance and fluorescein angiographic findings on presentation were consistent with an autoimmune retinopathy. Paraneoplastic etiology was ruled out, and antiretinal antibody testing revealed positivity for autoantibodies against GAPDH, aldolase, enolase, arrestin, as well as unnamed 48-kDa and 60-kDa proteins. ARA Western Blot and immunohistochemistry profiles were unchanged by either plasmapheresis therapy or passage of serum through the maternal placenta. However, the patient's 6-month and 8-year-old daughters appeared unaffected. CONCLUSION: This is the first report of nonparaneoplastic autoimmune retinopathy associated with myasthenia gravis, although a strong history of autoimmune disorders is a known risk factor. Our patient's antiretinal antibody panel was unaffected immediately after plasmapheresis treatment. Antibodies to GAPDH and unnamed 38-kDa and 86-kDa proteins were able to pass through the placenta into the fetal circulation, although their effect on the growing fetus is not clear.

The Walnuts and Healthy Aging Study (WAHA): Protocol for a Nutritional Intervention Trial with Walnuts on Brain Aging.

Introduction: An unwanted consequence of population aging is the growing number of elderly at risk of neurodegenerative disorders, including dementia and macular degeneration. As nutritional and behavioral changes can delay disease progression, we designed the Walnuts and Healthy Aging (WAHA) study, a two-center, randomized, 2-year clinical trial conducted in free-living, cognitively healthy elderly men and women. Our interest in exploring the role of walnuts in maintaining cognitive and retinal health is based on extensive evidence supporting their cardio-protective and vascular health effects, which are linked to bioactive components, such as n-3 fatty acids and polyphenols. Methods: The primary aim of WAHA is to examine the effects of ingesting walnuts daily for 2 years on cognitive function and retinal health, assessed with a battery of neuropsychological tests and optical coherence tomography, respectively. All participants followed their habitual diet, adding walnuts at 15% of energy (≈30-60 g/day) (walnut group) or abstaining from walnuts (control group). Secondary outcomes include changes in adiposity, blood pressure, and serum and urinary biomarkers in all participants and brain magnetic resonance imaging in a subset. Results: From May 2012 to May 2014, 708 participants (mean age 69 years, 68% women) were randomized. The study ended in May 2016 with a 90% retention rate. Discussion: The results of WAHA might provide high-level evidence of the benefit of regular walnut consumption in delaying the onset of age-related cognitive impairment and retinal pathology. The findings should translate into public health policy and sound recommendations to the general population (ClinicalTrials.gov identifier NCT01634841).

Purtscher-Like Retinopathy: Optical Coherence Tomography and Visual Field Findings.

A 30-year-old male presented with decreased vision in the right eye after a recent hospitalization for acute pancreatitis. On presentation, his visual acuity was 20/100 right eye (OD) and 20/20 left eye (OS). The funduscopic examination findings were consistent with Purtscher-like retinopathy (PLR). Cirrus HD-OCT (Spectral Domain Technology, Zeiss) of the right eye showed retinal nerve fiber layer swelling and significant subretinal fluid. Humphrey visual field (Central 24-2) revealed generalized defect on the right and inferior nasal step on the left. During the next 6 months, the patient had improvement in visual acuity (20/30 OD and 20/20 OS) and normalization of optical coherence tomography (OCT) findings. However, the visual field (VF) worsened bilaterally suggesting that the injuries induced by micro-infarctions at the level of the retinal nerve fiber layer (RNFL) were not reversible. To our knowledge, there have been no reports in the literature that compare high-resolution OCT and VF findings in patients with PLR.

Abnormalities of fundus autofluorescence in central serous retinopathy.

PURPOSE: To report abnormalities of fundus autofluorescence associated with acute and chronic central serous retinopathy (CSR). DESIGN: A prospective cohort study of patients with CSR was undertaken in which the intensity and spatial distribution of fundus autofluorescence were documented. METHODS: Fundus autofluorescence was recorded using a confocal laser scanning ophthalmoscope (cLSO) and the images compared with the fundus appearance and fluorescein angiograms in 69 eyes of 63 subjects with either acute or chronic CSR. Areas of increased and decreased autofluorescence were compared with ophthalmoscopic and fluorescein angiography abnormalities. Thirty patients with focal leakage on angiography and serous retinal detachment or pigment epithelial detachment were designated as having acute CSR. Thirty-three patients with diffuse leakage on fluorescein angiography, but without manifest detachment were classified as having chronic CSR. RESULTS: The mean age was 39 years (range 29-56 years) 14 were female and 49 male. Acute CSR of more than 4 months duration showed a mild diffuse increase in autofluorescence that corresponded with the detached area. The leaking point on the angiogram corresponded to a focal area of intense autofluorescence. In chronic CSR the autofluorescence was very irregular, there being regions with greater and less than the background levels of fluorescence. CONCLUSION: In acute CSR, increased autofluorescence may occur at the site of leakage and in the area of retinal detachment probably indicating an increased metabolic activity of the retinal pigment epithelium (RPE). Decreased or absent autofluorescence in long-standing lesions may indicate reduced metabolic activity of the RPE due to photoreceptor cell loss. Documenting photoreceptor cell loss with autofluorescence imaging may be useful in identifying patients who would not benefit from laser photocoagulation.