Looking up: eye remodeling supports aerial vision in the four-eyed fish Anableps anableps

This dual vision capability is supported by specialized adaptations to the eye, including a thicker dorsal (aerial) cornea and asymmetric expression of visual opsins: opn1mw1 in the ventral retina, and opn1lw1 in the dorsal retina.

To investigate the molecular and spatial basis of this asymmetry, we used single-nucleus RNA sequencing (snRNAseq) of the retina in combination with spatial transcriptomics of the whole eye. Our findings reveal that the asymmetric opsin distribution results from a developmental expansion of the ventral retina, which is adapted for detecting aerial light, alongside a reduction in the dorsal retinal domain responsible for aquatic vision.