Vitreoretinal lymphoma is a form of central nervous system (CNS) lymphoma that often is misdiagnosed as uveitis, but is the most common form of intraocular lymphoma. A proper diagnosis of vitreoretinal lymphoma requires the histological identification of lymphoma typed cells within the vitreous of the globe or retina which can be a trick due to reactive lymphocytes as well as necrotic regions in the retina. Contemporary approaches also require immunohistochemistry to reveal the monoclonality.
This rare form of lymphoma commonly has a poor prognosis and is often associated with a CNS lymphoma in aged populations. That said, historically treatment, like other retinal cancers was commonly enucleation. These days, chemotherapy combined with radiation therapy is more commonly used, though without good outcomes in many cases due to the difficulty delivering drugs into the eye from systemic administration. New approaches are being explored through the direct injection of drugs into the globe and those efforts are ongoing.
Fundus photos were made by James Gilman of the Moran Eye Center.
Trilobites were one of the most successful marine arthropods that lived from the Early Cambrian throughout the Devonian, finally going extinct in the Permian ages, a run of over 270 million years. They are well represented in the fossil record and even the earliest forms had complex compound eyes much like modern arthropods. These eyes had elongated lenses composed of calcite that modeling has revealed to provide excellent optical properties with good depth of field and little to no spherical aberration. These lenses brought light to photoreceptor cells at the base of the lens, but we’ve never before had an understanding of what that structure or anatomy looked like.
The problem of course with the fossil record is that very little internal structure remains in fossilized specimens. However, a very cool new study that examines trilobite eyes through X-ray tomography by Brigitte Schoenemann and Euan N. K. Clarkson reveals how these cells looked, down, perhaps to the cellular level. Followup work with μct-scanning and synchrotron radiation analysis reveals that the sensory structures (like rod or cone outer segments) are arranged in flower petal like structures around a central, diamond shaped photoreceptor cell body with pigment granules packed in-between. Its kind of like a modern limulus eye (image here).
It will be interesting to see if they can image other species of trilobite to get an evolutionary look at how eyes and perhaps primitive retinas developed over 500 million years ago.
Image Credit: Bryan William Jones, Ph.D.
Vision in fishes and crustaceans is a fascinating and understudied area. In past decades, there were far more studies on the visual systems of sea-dwelling creatures, but with the push towards applied or translational research, the number of reports in these species have dropped off, much to our detriment as one never knows where the applications of basic research will pay off.
At the same time, the whole study of bioluminescence and vision is an interesting examination of how organisms use bioluminescence for mating, warning or aposematism, crypsis or counter-illumination and predation. It is explicitly a visual phenomenon and as such, has informed a variety of investigations into biomedical, commercial and military applications. Continue reading “Interesting papers: Light and vision in the deep-sea benthos”
Jason Shepherd, Assistant Professor in Neurobiology and Anatomy at the University of Utah will be delivering a seminar titled “Cellular Mechanisms of Experience Dependent Plasticity in Mouse Visual Cortex” on March 19th at 12:00 in the John A. Moran Eye Center Auditorium.
Abstract: A myriad of mechanisms have been suggested to account for the full richness of cortical plasticity. We found that visual cortex lacking the activity-dependent gene Arc is imprevious to the effects of deprivation or experience. Using intrinsic signal imaging and chronic visually evoked potential recordings, we found that Arc KO mice did not exhibit depression of deprived-eye responses or a shift in ocular dominance after brief monocular deprivation. Moreover, Arc KO mice lacked stimulus-selective response potentiation, as in in vivo form of plasticity that resembles long-term potentiation (LTP). Although Arc KO mice exhibited normal visual acuity, baseline ocular dominance was abnormal and resembled that observed after dark-rearing. These data suggest that Arc is required for the experience-dependent processes that normall establish and modify synaptic connections in visual cortex.