To answer this question, we have to know what 'blindness' actually means. According to the Cambridge dictionary ( .org website), blindness is “the condition of being unable to see”. But we do realise that lions have eyes, they hunt and conduct themselves as if they CAN see. Take for example, an ant. If you put a finger in front of a strolling ant, she would bang against your finger and then change her path. She doesn't see you from a distance and changes her direction beforehand. Imagine standing in front of a lion, it would most certainly KILL YOU, giving you the reward for considering it blind. Of Course they are not blind, but of course this is not click bait. Let's make it all make sense. Also, not all ants are blind. Some have a very blurred vision and some, like Australia's bulldog ants, have excellent vision.
A term which we should be cognizant of is - “VISUAL ACUITY”, which is the ability of the eyes of an animal to distinguish shapes and tell objects apart in the visual space. Just like we measure distance in metres, pressure in pascal or temperature in degree celsius, we measure visual acuity in cycles per degree (cpd). Fortunately, we can imagine what that could be, just like we can imagine how hot 50°C is, or a metre is approximately the length from your fingertips to your neck or the opposite shoulder (depending on your height). To visualise cpd, extend your arm and give a thumbs up. The thumb’s nail width represents roughly one degree of visual space of the 360 that surrounds you (a circle around is 360). A cpd of 60 means that if 60 alternating black and white strips are painted on your thumb, you would be able to tell them apart. Humans have a cpd of around 60-70. A person with cpd 10 or less is reckoned legally blind.
Humans are really blessed when it comes to sight. Only a few preying birds outstand humans. Wedge-tailed eagle of Australia holds the record for the highest cpd possible - 138. A honeybees’ acuity is just 1 cpd. Nearly 98% of all insects have this low level of acuity. “All the detail within that nail would collapse into a uniform smudge.” A lion has 13 cpd, too close to a legally blind person’s. That means, if one makes more than 13 stripes on that nail, a lion would not be able to distinguish them as separate lines. To them, that field is just grey. If a lion's eyes were transplanted in a human, they would become antsy and categorically blind.
These animals are not actually blind. They just have enough acuity that they call for. All creatures are designed with just the optimal structure needed for them to function. A preying bird's vision is expendable to a lion, because it need not spot a mouse from a mile away. An ant does not need vision (at all) because it can function properly with its pheromones. This also solves a childhood mystery. We were told that zebras have black and white stripes to camouflage, but nothing in its habitat is white or black to blend into. It's all almost yellowy in there. But having stripes makes them a blurred blob, which gives lions a hard to spot them, their prime predators. Had they been solid, lions would easily spot them as a big dark blob. To lions, zebra is just a donkey from afar. Images belong to owner, no copyright intended.
Who has more and more power they become blind and then do mistakes which destroys them else they get absolute power and become like God . So nature made this beautiful arrangement.