Measuring rod-based vision

ScotopicKit

Striatech's ScotopicKit lets you extend the applications of your OptoDrum. With filter foils, you can stepwise reduce absolute light levels inside the OptoDrum to near darkness. Whether you want to monitor rod-based diseases, or ask questions about light adaptation - with the ScotopicKit you can evaluate your animals' visual threshold at different light levels, and characterize rod-driven vision.

Light and Dark Adaptation

Basic retinal neurophysiology

  • Add different numbers of filters in front of OptoDrum monitors to adjust ambient light level
  • Study time course and dynamics of light and dark adaptation

Scotopic Vision

Night vision in health and disease

  • Contrast sensitivity
  • Visual acuity
  • Track retinal degeneration
  • Evaluate new treatment options (stem cells, optogenetics, neuroprotection, ...)

Rod- and Cone-specific Diseases

Pre-clinical research

  • Compare optomotor behavior at different light levels.
  • Rod-based diseases can be revealed through optomotor deficits at scotopic light levels.
  • Animals with cone-specific diseases will likely have normal optomotor behavior at scotopic light levels.

USer voices

With scotopic optomotor measurements, I could show that mice see better at night due to the inverted nuclear architecture of their rods - a clear evolutionary advantage!

Dr. Kaushikaram Subramanian, Max Planck Institute , Dresden

Many genetic mouse lines reveal differences in visual abilities only under night-vision conditions. With the ScotopicKit, one is able to screen for such differences.

Dr. Hartwig Seitter, University of Innsbruck
The Optomotor Reflex

Background: Measuring rodent vision with innate reflex-behavior

All animals have reflexes that help to stabilize the image of the moving environment in their eyes. For example, if a person looks out the window of a moving train her eyes automatically follow the landscape. These compensatory eye movements are caused by the so-called optokinetic reflex. Many animals also have the optomotor reflex which triggers compensatory head movements.

These compensatory eye and head movements are only triggered if the moving stimulus can be seen by the animal. Thus, observing these innate reflexes can be used as a quantatative readout for visual performance needs of animals. In mice and rats, observing the optomotor reflex is particulary convenient: it does not require fixation or surgery, because the corresponding behavior can be observed macroscopically.

Differences between "normal" and scotopic optomotor measurements

The mammalian retina is sometimes called a "duplex retina" because of its two photoreceptor classes: cones support fast vision during daylight conditions (photopic vision), while rods are exquisitely light sensitive and support vision under low-light conditions (scotopic vision). During the transition between different light levels, complex adaptation mechanisms in the photoreceptors and in the retinal circuitry enable continued vision. By measuring the optomotor reflex with the OptoDrum, while changing light levels with the help of the ScotopicKit, you can obtain a behavioral readout of the consequences of light adaptation.

In many mammals, including mice, rats, and humans, rod photoreceptors constitute the majority of photoreceptors. Mutations in rod-specific genes are therefore underlying many retinal diseases, including diseases that lead to blindness. These mutations can affect the optomotor reflex, and this phenomenon can be caught earlier when looking specifically at vision driven by rods, under scotopic conditions. 

Even mutations that do not lead to blindness may have functional consequences that can only be seen under scotopic conditions - not only at the cellular and circuitry level in the retina, but also at the level of behavior. Optomotor behavior in particular, measured with the OptoDrum and the ScotopicKit, can provide a convenient readout in these cases.

Accessories and related Products

Filter Foils

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The ScotopicKit comes with a full set of filter foils. You can buy additional foils to replace old ones.

DarkAdapt

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Dark-adapt your animals in preparation for scotopic experiments. DarkAdapt can also be used to transport animals between your dark adaptation room and experimental room.

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