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UPenn - Vision Research Center Noninvasive Assessment of Visual Function Example Projects

 

December 2013: Animal Pupillometry

Pupillometry is supported by an A-2000 animal pupillometer located at the Stellar-Chance Lab, rm 332. The benefits of pupillometry are high sensitivity and simplicity.

The following records illustrate the use of pupillometry for evaluating results of gene augmentation therapy for the Leber Congenital Amaurosis 5 in a mouse model of this condition (lebercilin-/- mouse).

The right eye of a lebercilin-/- mouse was injected with a preparation of an AAV  carrying wild-type lebercilin cDNA.  Two weeks after the injection pupil reflexes from both eyes were tested.  Flashes delivered to the non-injected eye elicited no response (black trace). Flashes delivered to the treated eye  produced a clear pupil contraction (blue trace).

Both traces represent direct pupil reflexes.

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November 2013: Watermaze with a Cued Escape Platform

Watermaze with an escape platform

Watermaze with an escape platform

The main direction of recent work has been development of behavioral approaches to vision assessment. A fast, high throughput protocol for determining absolute thresholds within a range of 10-5  to 102  cd m-2 in a watermaze with a cued escape platform was developed and used for assessment of efficacy of gene therapy in a knock-out model of a human condition.

threshold plots

Determination of absolute visual thresholds in normal and knock-out mice in the watermaze, an illustration. The animals used were wild-type, mGlu6R-/- (no function in “on” bipolar neurons), and Nrl-/- (no rods) mice. The smooth curves are root mean square logistic fits                     F(I) =  1/{1+exp[-(I-I50)/b]}

Where I stands for illuminance, F for the frequency of success, I50 and b are constants, and I50 (the threshold) corresponds to the illuminance at which 50% of animals were able to find the platform.

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January 2012: Custom ERG Protocols for Assessing Visual Function in Mice

ERG Transducin Alpha

The noninvasive assessment module has developed a number of custom protocols for using the ERG to assess visual function in mice. These may be used in conjunction with apparatus associated with the module, and which is available for use by Penn investigators. An example is shown in the image, where ERG recordings of wild type and a knockout missing the transducin alpha subunit are shown for various adapting conditions and flash intensities. Data of this sort allow characterization of the change in visual function produced by deletion of the alpha subunit. The module can develop protocols appropriate for studying a variety of visual functions in mice. Contact Arkady Lyubarsky (arkady@mail.med.upenn.edu) if this is of interest to your lab.