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4

Short answer No. Not two irises are alike, including the irises of identical twins and even the two irises of one and the same person. This uniqueness of the human iris is used in iris scans. The variety of the iris is caused by its complex structure and coloring pattern. Source: Jean-Fran├žois Mainguet Background The iris is explained on Biometric ...


1

The eye color follow quite well mendelian inheritance rules... Probably your parents are heterozygote recessive for the blue color, hence the children have 25% of probability of having blue eyes. Let's say color of the eyes has 2 alleles "BLACK" for the dark eyes and "blue" for the light eyes. Your parents are probably both BLACK-blue, BLACK-blue. They show ...


2

He may have extreme acuity, or he may even have an extra cone type that allows him to see extra colors (and more color attunement may allow easier reading of those particular plates). But, you won't know anything for sure by asking on here. Take him to an ophthalmologist and let us know what the doc says! If you aren't 40+ and have 20/20 vision and he's ...


17

The "normal" visual acuity in the Anglosphere is the 20/20 vision which means that on a Snellen chart characters with 8,86 mm height can be read conveniently from a distance of approximately 6 m. Now there are many known people who have very sharp eyes, having the doubled acuity of 20/10. This means they can discern characters of only 4,43 mm height from ...


16

Short answer Visual acuity decreases with age. Your son's age is within the age range that visual acuities are best. Acuity starts to decrease from about age 45. Background Visual acuity (visual resolution) first increases from birth up until around 4-6 years. Note that in the following graph better acuities are represented by lower numbers (logMAR ...


3

According to the Mayo Clinic website: As you age, the tissue structures and muscles supporting your eyelids weaken. The skin may start to sag, and fat that is normally confined to the area around the eye (orbit) can move into the area below your eyes. Also, the space below your eyes can accumulate fluid, making the under-eye area appear puffy or ...


2

When we are sad, our emotions are in an overdrive and the parasympathetic nervous system triggers lacrimation i.e. tears, and we cry.


11

Short answer In humans it is basically the red choroid plexus in the back of the eye you are seeing on a flashed photo, while it is the green-reflecting tapetum lucidum in dogs. Background The red-eye effect in humans was explained nicely by Yale Scientific Magazine, and I adapted the following text from that source: The human eye can effectively adjust to ...



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