There has been a great deal of research on the eye of N. glauca.
These insects use their eyes for both day and night vision, which is used for prey capture and flight when searching for new habitats.
Notonecta glauca, like other insects, have a compound eye.

Specifically, their eye is an acone-type with corneal structure, which helps them create a sharp image when both in the water and in the air.
The acone is the site of the pupil.
Immonen et al. (
2014), found that backswimmers are able to see in both day and night light conditions because of:
their large variations in the peripheral photoreceptor cell properties
having a roust migration of pigment and photoreceptors
They also found that the green-sensitive peripheral photoreceptors function in a similar way as nocturnal Phasmatodea (or stick insects).

To protect their eye from direct sunlight during the day, the pigment cell's diaphragm are condensed, and during the night they open fully to allow as much light in as possible.
Notonecta glauca have two photoreceptor subsystems: 
Large and most sensitive peripheral photoreceptors
Smaller peripheral and central photoreceptors
The first subsystem is sensitive to green light, one of the colours in the visible spectrum.
This sensitivity helps the backswimmer see in dimmer light or at night.
The second subsystem allows the backswimmer to see in bright light and when in flight.
Notonecta glauca pupil (acone) take a different amount of time to adjust to light.
It takes the N. glauca approximately 40 minutes for the pupil to adjust to daylight and approximately 50 minutes to adjust to the light at night.
There has been a great deal of research on the eye of N. glauca. These insects use their eyes for both day and night vision, which is used for prey capture and flight when searching for new habitats. Notonecta glauca, like other insects, have a compound eye. 
Specifically, their eye is an acone-type with corneal structure, which helps them create a sharp image when both in the water and in the air. The acone is the site of the pupil. Immonen et al. (2014), found that backswimmers are able to see in both day and night light conditions because of:
their large variations in the peripheral photoreceptor cell properties
having a roust migration of pigment and photoreceptors
They also found that the green-sensitive peripheral photoreceptors function in a similar way as nocturnal Phasmatodea (or stick insects). 
To protect their eye from direct sunlight during the day, the pigment cell's diaphragm are condensed, and during the night they open fully to allow as much light in as possible. Notonecta glauca have two photoreceptor subsystems: 
Large and most sensitive peripheral photoreceptors
Smaller peripheral and central photoreceptors
The first subsystem is sensitive to green light, one of the colours in the visible spectrum. This sensitivity helps the backswimmer see in dimmer light or at night. The second subsystem allows the backswimmer to see in bright light and when in flight. Notonecta glauca pupil (acone) take a different amount of time to adjust to light. It takes the N. glauca approximately 40 minutes for the pupil to adjust to daylight and approximately 50 minutes to adjust to the light at night.
Notonecta glauca