Two different visual stimuli that cause axial eye shortening have no additive effect

Area of Science:

• Ophthalmology
• Vision Science
• Physiological Optics

Background:

• Myopia progression is a significant public health concern.
• Previous research identified specific visual stimuli that may inhibit myopia by altering eye axial length.
• Two such stimuli include digitally filtered movies ("red in focus") and inverted contrast text.

Purpose of the Study:

• To investigate the combined effect of the "red in focus" filter and inverted contrast text on human eye axial length.
• To determine if these stimuli have an additive effect on myopia inhibition.

Main Methods:

• Twenty-two emmetropic subjects participated in the study.
• Subjects read text (standard and inverted contrast) for 30 minutes under different filter conditions (unfiltered or "red in focus").
• Axial length was measured using low-coherence interferometry before and after each reading session.

Main Results:

• Reading standard contrast text showed no significant change in axial length.
• Reading inverted contrast text resulted in a significant eye-shortening effect, consistent with prior studies.
• Surprisingly, combining inverted contrast text with the "red in focus" filter led to eye lengthening, not shortening.

Conclusions:

• The "red in focus" filter, when combined with inverted contrast text, negates the expected eye-shortening effect.
• This counterintuitive result may be due to the filter removing crucial blue channel spatial information required for the retina to utilize longitudinal chromatic aberration (LCA) analysis for choroidal thickening.