Photographic Screening for Factors Leading to Amblyopia

Abstract

Two types of photographic systems have been developed to screen for amblyogenic factors. Each has evolved over the past 10 to 15 years, and each has been evaluated for potential use in mass screening situations.

In each system the image of a strobe flash is photographed after having been reflected off the patient's fundus. The two systems, “off-axis” and “on axis,” are differentiated by the placement of the flash source with respect to the optic axis of the instrument. Each system produces images of both eyes simultaneously.

These systems, the “off-axis” system, and the “on-axis” system, have been used to photographically screen for significant refractive errors. The off-axis system additionally evaluates for clarity of the media (by assessing red reflex) and screening for strabismus (by corneal light reflex). Advantages as well as limitations of the particular systems are defined. Further refinements of each system and better understanding of their limitations are in order before widespread application to mass screening settings is performed. Nevertheless, such systems offer the distinct potential for screening of amblyogenic factors in the pre-verbal infant and child.

• photorefraction
• amblyopia
• vision screening
• infant vision