External photography is used to document pathology of the eyelids, ocular adnexa, ocular surface, and anterior segment. High resolution images effectively document the color, size, position, and extent of lesions within external and anterior ocular structures.
Color Fundus Photography
OSOD specialists work independently or in collaboration with fundus photograph reading centers to:
- Document the appearance of the retina for GLP and GCP studies.
- Consult in the design, conduct, and analysis of multi-center clinical trials and epidemiologic studies that use ophthalmic imaging.
- Apply a large array of digital and film-based fundus cameras for imaging the retina, including the Micron III (Phoenix Labs Inc), for photographing the fundus in mice and rats.
Fluorescein angiography is used to assess the integrity of the retinal and choroidal vasculature. In pre-clinical studies it has been particularly useful in assessing the efficacy of anti-VEGF compounds in the laser animal model of AMD.
Fundus autofluorescence imaging has been shown to be a useful tool to document metabolic changes at the level of the retinal pigment epithelium (RPE), suggesting areas of high risk for visual function loss.
Slit Lamp Photomicrography
Slit lamp photomicrography is used to document the health of the adnexa and anterior segment, including finite evaluation of specific layers of the cornea and lens, and microscopic features of the iris as observed through a slit lamp biomicroscope.
The anterior chamber and trabecular meshwork can also be imaged using a variety of gonioscopic lenses. This procedure is suitable for a wide variety of species in pre-clinical studies, as well as clinical research.
Anterior Segment Optical Coherence Tomography (AS-OCT)
Optical coherence tomography (OCT) is a non-invasive imaging technique that provides three-dimensional and cross-sectional views of ocular structures with a resolution that approaches that of light microscopy. OCT is widely used clinically for diagnosis and longitudinal monitoring of many retinal disorders.
Anterior segment optical coherence tomography utilizes semi-coherent light with high absorption and low penetration, allowing visualization and assessment of the shape, size and position of anterior segment structures including the cornea, iris, and lens. In preclinical studies, it is often used for longitudinal evaluations of the cornea, anterior chamber angle, iris, and lens. At OSOD, we have experience acquiring high-quality AS-OCT images using the Heidelberg Spectralis® in tandem with an anterior segment lens, or with the Visante® AS-OCT unit (Zeiss-Meditec).
Posterior Segment Optical Coherence Tomography
Optical coherence tomography (OCT) is a non-invasive imaging technique that provides three-dimensional and cross-sectional views of ocular structures in the posterior segment including the retinal layers, vitreous, and portions of the choroid and optic nerve.
OCT is widely used clinically for diagnosis and longitudinal monitoring. It is particularly useful in the evaluation of macular edema, macular holes, glaucoma, and age-related macular degeneration. Preclinically, OCT is used for visualizing the posterior segment and assessing changes in retinal layers in drug safety studies. In tandem with our colleagues at MERIT CRO, Inc., OSOD has developed, validated, and published a semi-automated protocol for accurate segmentation and measurement of retinal layer thicknesses in both human patients and laboratory species.
OSOD primarily uses the Heidelberg Spectralis® instrument for acquisition of OCT images in preclinical studies.
Specular photomicroscopy is used to assess the integrity of the corneal endothelium. The instrument provides an image of the individual cells of the endothelial layer and determines cell counts, size, shape and organization. The presence of abnormal cellular organization may indicate the presence of toxicity to the corneal endothelium. OSOD uses both the Topcon SP-300™ contact system and the Konan CellChek XL™ for projects requiring specular microscopy.
The use of high frequencies has greatly increased the spatial resolution of non-invasive ultrasound.
High resolution ultrasound instruments are used to visualize lesions in the anterior segment, including the iridocorneal angle, as well as the posterior segment.
Ultrasound biomicroscopy is used to produce images of anterior segment structures or sub-surface lesions. This technique has proven useful in imaging conjunctival, lacrimal, and eyelid pathology, and in detecting and measuring anterior segment lesions.