Ocular Pathology

OSOD has unparalleled expertise in working with clients to provide a full range of eye pathology services including consultation regarding study design, recommendations for animal models, examination and processing of tissue samples, and peer review. We would like to help you by:

 - Providing expert opinion in the pathology of spontaneous eye diseases and toxicities in animal models as well as humans (choroidal neovascularization (CNV), glaucoma, retinal abnormalities, ocular implants, ocular inflammation, corneal diseases, diabetic retinopathy, and cataract).
 - Utilizing the best technology to offer slide preparation services including paraffin, plastic, EM, and immunohistochemistry.
 - Receiving and processing wet tissue for light microscopy, IHC, and transmission and scanning EM.
 - Consulting on appropriate fixation and tissue processing for ocular tissues.

Ocular Histopathology

  • Histopathology refers to the study of eye disease at the microscopic level. We advise and may participate in the collection, preparation, and staining of tissue, and provide interpretation of specimen after processing. We have demonstrated expertise in each of the following areas:​
    • Collection of ocular tissues, fluids, and adnexa
    • Processing, sectioning, and non-GLP microscopic evaluation
    • Multiple ocular fixation techniques including OCT frozen blocks, immersion, injection of fixative into the vitreous, and upper-body perfusion
    • Trimming eyes to isolate internal anatomic structures, lesions, or adnexa
    • Areas of interest embedded in epoxy resin, glycol methacrylate, and paraffin for light or electron microscopy
    • Peer review of client-supplied slides​
  • OSOD's ocular histopathology service can provide basic diagnostic services as well as investigative analyses designed to assess the pathogenesis or prognosis of ocular disease, effectiveness, and safety of treatment in toxicity studies, and epidemiology of spontaneous ocular disease in animals and humans. We have access to a reference slide library that contains over 23,000 pathology specimens dating back to 1921, and we have the ability to obtain fresh ocular tissue from normal samples as well as those representing a variety of eye diseases. We also have extensive experience in testifying as expert witnesses on ocular pathology issues at FDA hearings and trials.

Bright Field Microscopy

  • Bright Field (or ‘Light’) microscopy is the most popular microscope technique and is the backbone of all pathology to study the morphology or pathology of tissue. Our pathologists are among the world’s experts in the interpretation of changes in ocular tissues.
  • We have experience in both spontaneous ocular disease and in ocular toxicologic pathology. We can recommend the most optimized protocols, the use of special stains or viewing techniques and, if needed, image analysis schemes.


  • Immunohistochemistry is a microscopy technique that allows the observer to label and localize particular antigenic tissue components, such as infectious agents, structural molecules or signaling molecules. The technique is powerful but needs to be approached very carefully as it is only useful if the protocols used are carefully chosen and then verified in each species and with each fixative used.

Development of Models/Cell Lines

  • Pharmaceutical companies and instrument companies sometimes require the development of animal models and/or cell lines of diseased tissues for use in studying the effectiveness or toxicity of drugs or other treatments. Our ocular pathology service is equipped to provide these services. Examples include:
    • A model of wet macular degeneration induced by light exposure in rats and mice
    • Transgenic models of ocular tumors

Transmission Electron Microscopy (TEM)

  • The transmission electron microscope (TEM) images are useful for examining intracellular structures. The magnification and resolution provided by TEM allow the evaluation of the cellular structure to the level of cellular organelles.
  • Subtle changes not detectable on light microscopy can be recorded and graded. This additional power can be useful in studies of toxicity and in studies of pathogenesis or efficacy. Because TEM is a powerful tool, it is important that the user has experience in using it.

Scanning Electron Microscopy (SEM)

  • Scanning electron microscopy (SEM) allows the study of surface structures of tissue under great magnification and in three dimensions. The SEM produces very high-resolution images with a depth of field that can reveal the topography of ocular cells within multiple layers of healthy or diseased tissue. SEM images convey information about cell composition, contour, and diameter and provide clues as to how ocular tissues are organized.

Atomic Force Microscopy (AFM)

  • The atomic force microscope is a very useful, yet under-utilized tool in the vision sciences. It allows imaging in liquid with minimal sample preparation (no labeling, fixing, or coating) and yields topographic characterization of surfaces at high resolutions not achievable by optical microscopy. Molecular-scale features of normal and diseased eyes can be identified and compared within the native environment of the sample and in real time providing insight into molecular reorganizations not observable by other techniques. AFM has been used in the imaging of the ommatidium surface of Diptera compound eyes, rhodopsin in the native membrane, and aquaporin in a lens capsule.