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Photorefractor and Keratometer / Photorefractor and Keratometer


The infrared eccentric Photorefractor was originally developed by Prof. Frank Schaeffel at the University of Tübingen (Germany), and is being used by numerous labs world-wide. Based on the analysis of retinal reflection of an eccentrically placed IR light field, the Photorefractor automatically and conveniently measures the eye's refracative state in alert small laboratory animals.



Myopia, also known as short-sightedness, or near-sightedness, is a common disease where close obejcts can still be seen clearly, but distant objects appear blurry. In myopia, the eye is too long, and the optics of the eye focuses the image in front of the retina. High myopia can be dangerous, because the retina can detach due to the long eye ball, and is a leading cause of blindness. The degree or severity of myopia can be described as the refractive state of the eye.

The refactive state can be measured with an eccentric Photorefractor. The fundus is observed through the pupil while an eccentrically placed light source illuminates the eye. The pupil reflects the light source back to the observer (e.g., a camera), similar to the red-eye effect known from photography. Depending on the amount of defocus, this reflection is not filling the pupil evenly, but it is displaced laterally. The asymmetry of the reflection is directly correllated with the strength of the refractive error.

Striatech's Photorefractor is designed to measure the refractive state in alert small laboratory animals. It is fully integrated (camera, light source, and provided analysis software) to obtain results quickly and automatically, even in alert and moving animals. Building upon the successful approach and design of Prof. Frank Schaeffel (University of Tübingen, Germany), it can be used with all common small animal models of myopia research: mice, rats, Guinea pigs, and chicken.


Fully automated process

Automated eye detection · Automated analysis of pupil diameter · Automated analysis of refractive state · Fast, objective, and bias-free results


No fixation or surgery is required · Animal can be awake and alert · Disease progression can be monitored over time because animals can be tested repeatedly, even daily

Cost saving and effective

No animal training is necessary · No specialized training of personnel needed: the software does the work for you! · Data can be obtained within a few seconds

Easy handling and maintenance

Fully integrated system, ready to use · Comes with convenient storage/transport case · Delivered with necessary accessories, including animal platform and cable to connect to your computer

For various animal models

One device adapable to various animal models with one-time calibration: mouse · rat · guinea pig

Journal Citations

Zhu, X., Du, Y., Li, D. et al. Aberrant TGF-β1 signaling activation by MAF underlies pathological lens growth in high myopia. Nat Commun 12, 2102 (2021).

SCHAEFFEL, FRANK PhD; BURKHARDT, EVA CTA; HOWLAND, HOWARD C. PhD; WILLIAMS, ROBERT W. PhD Measurement of Refractive State and Deprivation Myopia in Two Strains of Mice, Optometry and Vision Science: February 2004 - Volume 81 - Issue 2 - p 99-110

Violet light suppresses lens-induced myopia via neuropsin (OPN5) in mice

Xiaoyan Jiang, Machelle T. Pardue, Kiwako Mori, Shin-ichi Ikeda, Hidemasa Torii, Shane D’Souza, Richard A. Lang, Toshihide Kurihara, Kazuo Tsubota