How light and the body’s internal clock influence daily eye pressure changes in mice lacking specific brain signaling molecules

Intraocular pressure in mice exhibits a 24-hour sinusoidal rhythm, peaking during the dark phase.

• Wildtype mice show significant daily variations in intraocular pressure, with the lowest values during the light phase.
• Transferring wildtype mice to constant darkness maintains the pattern of intraocular pressure changes observed under light/dark conditions.
• VPAC2 receptor knockout mice demonstrate a sinusoidal pattern of intraocular pressure under light/dark conditions, but lose rhythmicity when in constant darkness.
• PACAP deficient mice show significant oscillations in intraocular pressure in both light and dark phases, though with reduced amplitude compared to wildtype.
• The findings suggest that the circadian master clock primarily regulates daily intraocular pressure rhythms, with light and darkness having a lesser effect.

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