StriatechJournal Club

IR Photorefraction and IR Photokeratometry - Measuring Refractive State and Corneal Curvature in Animals and Humans

Prof. Frank Schaeffel - University of Tübingen, Germany

Live date was Oct 07th, 2021

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While there are sophisticated and highly precise autorefractors and keratometers commercially available to measure refractive state and corneal power maps in humans, it is difficult to measure small eyes of animal models like mice or guinea pigs. Prof. Frank Schaeffel has overcome this problem and has developed eccentric infrared (IR) photorefraction for small animal models, with the first version published in 1986 (Vision Research). Since then, IR photorefraction has been continuously improved. The device was first applied to mouse eyes in 2002, where it remains the only currently available refraction technique. It is used by a considerable number of laboratories around the world.
An advantage of the device is speed with over 100 measurements per second, depending on the camera frame rate. Frank Schaeffel will highlight its optical principles, the image processing algorithms, its calibration and its potential pitfalls.

He will also describe IR photokeratometry (used to measure the corneal radius of curvature), the underlying image processing algorithms, calibration and some applications in mouse and chicken eyes. This technique made it possible to show in 1987 that birds can accommodate by changing the curvature of the cornea.

Key Topics

For both IR photorefraction and IR photokeratometry, we will cover:

  • history
  • application
  • benefits
  • optics
  • software algorithms
  • calibration

Learning Objectives

Applications, benefits, and pitfalls of IR photorefraction and IR keratometry

Background Reading

Lack of oblique astigmatism in the chicken eye. Maier FM, Howland HC, Ohlendorf A, Wahl S, Schaeffel F.
Vision Res. 2015 Apr;109(Pt A):68-76.
doi: 10.1016/j.visres.2015.02.002.

Measurement of refractive state and deprivation myopia in two strains of mice. Schaeffel F, Burkhardt E, Howland HC, Williams RW.
Optom Vis Sci. 2004 Feb;81(2):99-110.
doi: 10.1097/00006324-200402000-00008.

Natural accommodation in the growing chicken.
Schaeffel F, Howland HC, Farkas L.
Vision Res. 1986;26(12):1977-93.
doi: 10.1016/0042-6989(86)90123-9.

Corneal accommodation in chick and pigeon. Schaeffel F, Howland HC.
J Comp Physiol A. 1987 Mar;160(3):375-84.
doi: 10.1007/BF00613027.

A large number of mouse myopia studies using IR photorefraction can be found here.

About the speaker

Prof. Frank Schaeffel

Prof. Frank Schaeffel

Professor Neurobiology of the Eye, Ophthalmic Research Institute University of Tuebingen, and Guest Professor at the Institut of Molecular and Clinical Ophthalmology (IOB) Basel
University of Tübingen, Germany


Prof. Frank Schaeffel has studied biology and physics at the University of Freiburg followed by a PhD in biophysics on the visual system of the fruit fly. After two postdoctoral positions at Cornell University (Ithaca, NY, USA) with Howard Howland (1985-1988) and at the Max-Planck-Laboratory at the Eye Clinics (Munich, Germany) with Prof. Eberhard Zrenner (1988-1989), he became research associate and Schilling Foundation Professor at the University Eye Clinics Tübingen (Germany). Since 2000, he has been C3 professor and head of the Section of Neurobiology of the Eye at the Research Institute of Ophthalmology in Tübingen. Frank Schaeffel is senior professor since 2019 and guest professor at the Institute of Molecular and Clinical Ophthalmology Basel (IOB) since 2020. In the IOB Myopia Research Group, Frank Schaeffel works with other scientists to develop and study visual stimuli to reduce eye growth. This research involves human subjects and also studies visual control of eye growth in mouse models.

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