This is a spider-like webbing across the cat’s eye that you see in the photograph. In the photograph it looks as if the cornea has been hit by an object and shattered. But that’s not the case. The picture caught my eye on the Reddit.com website. The owner/caregiver of the cat asked if anybody knew what was going on. I had never seen it before, and I will presume that it is quite rare in domestic cats. Although, it is not uncommon in newborn humans as it is seen in 95% of neonates and is a common congenital anomaly.
Persistent papillary membrane is an eye condition in which remnants of a faecal membrane remains across the eye. This membrane exists at the faecal stage to supply blood to the lens. It normally atrophies i.e., disappears, from the time of birth and over the early weeks of life. If the atrophying does not take place you end up with persistent papillary membrane as shown in the photograph.
The condition exists in humans in just the same way as is the case with so many illnesses that we share with domestic cats. Persistent papillary membrane strands normally connect to the iris, but they can connect to the cornea or lens of the eye.
Vets don’t normally treat this condition. As I understand it the eyesight is not normally impaired enough to warrant an operation to remove the structure when considering all aspects of the operation including risk.
At the embryonic stage, the iris forms as a solid sheet of mesodermal tissue known as the pupillary membrane. The ‘mesoderm’ is a germ layer that arises during gastrulation.
Sources: various including, Google Search results, Science Direct and Wikipedia.
Below are some more articles on the eye.