Two researchers from the Lions Eye Institute have taken out the top spot in the 2023 Nikon Small World Photomicrography Competition. Hassanain Qambari is a research student and Jayden Dickson is a research assistant with the Physiology and Pharmacology Research Group. They submitted a microscopic photograph of a rodent optic nerve head showing the intricacies of retinal vasculature. In the image above, astrocytes are shown in yellow and contractile protein in red.
Hassanain said, “I entered the competition because I thought it would be a great way to showcase my work and bring to light how intricate the retina is and why the study of retinal diseases poses such a challenge.”
As part of his research, Hassanain is investigating ways to detect diabetic retinopathy, a complication of diabetes, earlier in the disease progression. Diabetic retinopathy can damage the tiny blood vessels inside the retina at the back of the eye. It can cause bleeding and swelling which affects vision in a number of ways including blurry or distorted central vision, colours appearing faded, difficulty seeing at night or limited peripheral vision. In severe cases, diabetic retinopathy can cause blindness.
About the image
The staining of the vasculature was achieved via cannulation and perfusion of the ophthalmic artery (100-120 microns diameter), a technique pioneered by the Lions Eye Institute Physiology and Pharmacology research team more than 20 years ago. The intravascular perfusion technique was used to label the contractile proteins and the vasculature and once this was complete, the retina was dissected, separating it from the sclera and choroid. Because astrocytes are present in the top layer of the retina, intravascular perfusion cannot reach this structure and instead it must be immersion stained. Once both methods of labeling were completed, the retina was imaged with a Nikon Confocal microscope under a 20x objective lens. Lasers of different wavelengths were used to excite molecules that are bound to the cellular markers of interest.
Retinal astrocytes (yellow) function to maintain neuronal homeostasis, provide neurotrophic protection and form part of the blood-retinal-barrier together with pericytes and endothelial cells. In an activated state, astrocytes undergo reactive gliosis in response to insults such as trauma, ischemic damage, neuroinflammation, or neurodegeneration. This response seeks to regain retinal homeostasis and involves both structural and functional changes of glia, however, this process may become maladaptive and constitute the primary pathogenic element.
Contractile proteins (red) of the vasculature function to regulate blood flow in order to meet the dynamic retinal metabolic demands. Previous studies have shown that retinal hemodynamics is altered in subclinical disease. Thus, alterations to the retinal vascular contractile proteins may alter regional perfusion patterns and initiate or propagate neuronal or cellular injury related to diabetic retinopathy.
The retina has the greatest metabolic demand of any tissue in the body. Because of this the vasculature is highly important in meeting the retina’s actively changing metabolic demands in response to neuronal function. This is heightened due to the lack of autonomic innervation in the retina, instead the eyes metabolic demand is relied upon by local vascular mechanisms. Thus, neuronal activity evokes localised changes in blood flow which involves a coordinated interaction between the glia, vasculature and neurons. The retinal vasculature provides the metabolic support for all the cellular components of the retina.
We are grateful to the Stan Perron Charitable Foundation for supporting this research.
See below for a news interview with Hassanain Qambari on ABC.