To what extend the white spot can affect the vision of mouse and do you have better practice to minimize the occurrence of them?
P.S: I keep the eye covered with animal eye gel, try to minimize the direct light from the lamp, but sometimes the white spot becomes so obvious within 1hr that it almost occupy most of the eye.
Many Thanks!
Hi.
As I understand this is the same thing we observed when doing preclinical PET and SPECT.
Mouse are very sensitive to light, and when they are anesthetized they can not protect themselves, so you have to be very careful not to point strong light sources directly to them. If you do so, you will produce cornea damage do them, that is what the white spots are.
As Mao says, the eye gel provides to keep the eyes dry can help preventing these.
Protect from light with good amount of artificial tear gel and try covering their eyes with folded gauze or cloth through out procedure.
The sensitivity of rodents to light is greater than that of humans. Direct light during surgery can rapidly cause retinal damage and cataract formation, specially in albino animals. It is adviced to keep the eyes hydrated during surgery and also to protect them from prolonged bright light.
In our lab we liberally apply Lacrilube to the surface of the eyes once the animal is anesthetized. Prevents any drying during the surgery.
Does the white spot resolve post surgery?
The white spot could be caused by hypotension due to low cardiac output, which leads to the collapse blood vessels. The brain, the eyes, and the heart will become ischemic if the level of hypotension is low enough.
All the ointment in the world doesn't help and sometimes, too much ointment can be detrimental because it will attract debris that can lead to ulcerations especially during recovery in a cage with bedding.
see: http://www.anesthesiaweb.org/hypotension.php
Hi Janet, the white spot usually disappears gradually during the recovery stage. I later find a complete wetting of the cornea during the whole surgery dramatically diminishes the chance of having white spots. In addition, it is good to avoid a direct surgical lighting towards the eyes.
Thanks for putting forward a possible cause by the hypotension. The cardiac output diminishes for sure when the mouse is anesthetized.
Good luck to your research!
Jiahao
Hi,
I think Janet Wolforth is right. I am doing in vivo recordings on visual cortex and it is really important for me to keep the eye in a good shape. We observe sometimes a white spot in (it is in the eye not on the cornea) the eye of animal (looks a bit like foggy eye), which disappears while we lower the anaesthesia (we use isoflurane). Also we observed that such eyes are connected with luck of visual response from the cells, so the hypotension which was mentioned before by Janet would explain all the things well.
Even if we use the same age of animals and we keep standard doses of isoflurane with some animals we see that it is or too low (they react for pinching so we need to go upper with the dose) or it is to high (we observe the foggy eye). There is some variability then and we just keep observing our animals all the time during experiment carefully.
In our case while we lower the anaesthesia the eye comes back to the normal state after few minutes.
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