Spatial and spectral imaging of retinal laser photocoagulation burns

NoThe purpose of this research was to correlate in vivo spatial and spectral morphologic changes of short- to long-pulse 532 nm Nd:YAG retinal laser lesions using Fourier-domain optical coherence tomography (FD OCT), autofluorescence (AF), fluorescein angiography (FA), and multispectral imaging. Ten eyes with treatment-naive preproliferative or proliferative diabetic retinopathy were studied. A titration grid of laser burns at 20, 100, and 200 milliseconds was applied to the nasal retina and laser fluence titrated to produce four grades of laser lesion visibility: subvisible (SV), barely visible (BV, light-gray), threshold (TH, gray-white), and suprathreshold (ST, white). The AF, FA, FD-OCT, and multispectral imaging were performed 1 week before laser, and 1 hour, 4 weeks, and 3 and 6 months post-laser. Multispectral imaging measured relative tissue oxygen concentration. Laser burn visibility and lesion size increased in a linear relationship according to fixed fluence levels. At fixed pulse durations, there was a semilogarithmic increase in lesion size over 6 months. At 20 milliseconds, all grades of laser lesion were reduced significantly in size after 6 months: SV, 51%; BV, 54%; TH, 49%; and ST, 50% (P < 0.001), with retinal pigment epithelial proliferation and photoreceptor infilling. At 20 milliseconds, there was healing of photoreceptor inner segment/outer segment junction layers compared with 100- and 200-millisecond lesions. Significant increases in mean tissue oxygenation (range, four to six units) within the laser titration area and in oxygen concentration across the laser lesions (P < 0.01) were detected at 6 months. For patients undergoing therapeutic laser, there may be improved tissue oxygenation, higher predictability of burn morphology, and more spatial localization of healing responses of burns at 20 milliseconds compared with longer pulse durations over timeOptimedica Corp., the Manchester Academic Health Sciences Centre, and the NIHR Manchester Biomedical Research Centre. JD was funded by a College of Optometrists PhD Studentship, United Kingdom

High-resolution hyperspectral imaging of the retina with a modified fundus camera

NoThe purpose of the research was to examine the practical feasibility of developing a hyperspectral camera from a Zeiss fundus camera and to illustrate its use in imaging diabetic retinopathy and glaucoma patients. The original light source of the camera was replaced with an external lamp filtered by a fast tunable liquid-crystal filter. The filtered light was then brought into the camera through an optical fiber. The original film camera was replaced by a digital camera. Images were obtained in normals and patients (primary open angle glaucoma, diabetic retinopathy) recruited at the Manchester Royal Eye Hospital. A series of eight images were captured across 495- to 720-nm wavelengths, and recording time was less than 1.6s. The light level at the cornea was below the ANSI limits, and patients judged the measurement to be very comfortable. Images were of high quality and were used to generate a pixel-to-pixel oxygenation map of the optic nerve head. Frame alignment is necessary for frame-to-frame comparison but can be achieved through simple methods. We have developed a hyperspectral camera with high spatial and spectral resolution across the whole visible spectrum that can be adapted from a standard fundus camera. The hyperspectral technique allows wavelength-specific visualization of retinal lesions that may be subvisible using a white light source camera. This hyperspectral technique may facilitate localization of retinal and disc pathology and consequently facilitate the diagnosis and management of retinal disease

Supplementary Material for: Visualization and Identification of Silicone Oil Emulsification Using Dynamic Infrared Confocal Scanning Laser Ophthalmoscopy

Silicone oil (SO) plays a key-role as an intraocular tamponade in managing complex vitreoretinal diseases. However, its emulsification can lead to severe irreversible anterior and posterior segment complications. Traditional imaging often struggles to visualize SO, necessitating advanced techniques. This study aimed to introduce and evaluate the use of dynamic infrared confocal scanning laser ophthalmoscopy (IRcSLO) in imaging SO and its emulsification. Two patients, post pars plana vitrectomy with SO injection for retinal detachment, were imaged and recorded using the Heidelberg Retina Tomography Spectralis IRcSLO, focusing on the visualization of SO status and emulsified droplets. IRcSLO imaging technique effectively visualized emulsified SO droplets, even in cases where SO was removed. The droplets were identified as micron-sized, spherical entities, with non-uniform distribution. Case presentations highlighted the variability in SO emulsification patterns and the technique's ability to detect even tiny, emulsified droplets. Therefore, dynamic IRcSLO emerges as a potent imaging modality for SO emulsification visualization. It offers insights into droplet count, motility, and localization within the vitreous cavity. This technique holds promise for future studies focusing on emulsification timing, contributing factors, and potential preventive measures. It also offers a deeper understanding of emulsified SO droplet dynamics across different SO viscosities

Supplementary Material for: Home Artificial Nutrition in Switzerland: An Epidemiological Survey from 2005 to 2009

<b><i>Background and Aims:</i></b> Home artificial nutrition (HAN), including oral nutritional supplements (ONS) and enteral (HEN) and parenteral (HPN) nutrition, is an established, important treatment for malnourished patients. The aim of this study was to analyze the epidemiological data of patients on HAN in Switzerland. <b><i>Methods:</i></b> This retrospective study recorded all new cases of HAN in Switzerland from January 2005 to December 2009. <b><i>Results:</i></b> A total of 12,917 cases were recorded: 6,731 (52%) males and 6,186 (48%) females, with a mean age of 65.0 ± 17.6 years. The number of patients on ONS was 7,827 (57.4%), on HEN 3,966 (39.4%) and on HPN 433 (3.2%). The most common underlying disease category was neoplasms (6,519, 50.7%). The number of patients on ONS increased from 57.0% (n = 1,252) to 60.8% (n = 2,039), and on HPN from 2.1% (n = 45) to 4.0% (n = 134) between 2005 and 2009. <b><i>Conclusions:</i></b> This first analysis of the large-scale Swiss registry of HAN shows that approximately half of the patients received ONS, whereas HPN was rarely delivered. The frequency of ONS and HPN increased from the year 2005 to 2009. In accordance with previous European studies, malignant tumors were by far the most frequent indication for HAN