Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2023 Mar 7;6:246. doi: 10.1038/s42003-023-04575-x

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2023

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Fig. 1 — Diagrams of apposition and superposition eyes demonstrating the geometric tradeoffs between D, Δφ, and FOV for spherical (a. and b.) and non-spherical eyes (c. and d.). a In spherical apposition eyes, D directly determines sensitivity while Δφ inversely determines acuity. b In superposition eyes, migrating pigment (indicated by the arrows) allows the ommatidia to share light, increasing the eye’s sensitivity. As a result, these eyes generally adhere to a spherical design. c-d In nonspherical eyes, the intersection of ommatidial axes differs from the center of curvature, with ommatidial axes askew from the surface of the eye. Consequently, FOV and Δφ are not externally measurable and the effect of D on sensitivity is reduced by greater angles of skewness. c. When the distance to the intersection is greater than the radius of curvature, FOV and Δφ decrease, increasing average spatial acuity by directing more ommatidia over a smaller total angle. d Inversely, when the distance to the intersection is less than the radius of curvature, FOV and Δφ increase, decreasing average spatial acuity by directing fewer ommatidia over a smaller total angle. In both cases, optical sensitivity is lost because skewness reduces the effective aperture of the ommatidia.