When a person looks at the sun, his receptors are irritated, lacrimation begins, then irritation of the nasal passages occurs, which causes sneezing.
Research shows that 35% of people experience a "light sneeze reflex". When they get out of the dark into a bright light, they sneeze. There is evidence that such a predisposition is inherited.
The most convincing theory of the light sneezing reflex states that a bright light that irritates the optic nerve of each eye somehow affects the receptors that play a role in the ordinary sneezing. The visual and olfactory receptors are located close to each other, like the optic and olfactory nerves. Indeed, these nerves enter the brain at almost the same point. In some people, after a long period of being in the dark, when exposed to bright light, the pupils do not contract and the eyes become irritated. For unknown reasons, the optic and olfactory nerves "close", and the brain perceives the visual stimulus as olfactory, that is, sent by the nose, not the eyes. The brain stimulates sneezing to get rid of the irritant as if it were dust, dirt, pollen, or some other foreign substance. In addition, when bright light enters the eyes, tears may appear due to severe visual stress. Tears flowing from the lacrimal canals can themselves cause sneezing, as it happens in cases when they are not provoked by bright light.
Bright light increases tear production as a protective reaction of the eyes. The excess tear fluid passes through the lacrimal canal into the nose and, when salty, irritates the sinuses, which in some people leads to sneezing.
This effect is called photic sneeze. But not everyone has it. The researchers conclude that between 17 and 35 percent of the population is affected. Also, in English, this phenomenon is called achoo, which translates as an autosomal dominant uncontrolled helio-ophthalmic outbreak.
In 2010, a group of geneticists led by Nicholas Ericsson discovered two separate nucleotide polymorphisms that are associated with sneezing under exposure to bright light. The result was obtained through the study of ten thousand genotypes of customers of the company where Ericsson worked. These polymorphisms are changes to single letters. One of them is called rs10427255, and the other, about which is known a little less so far, is rs11856995. One is located near the gene for light-induced seizures. This suggests a connection between the two syndromes.
Sneezing is an unconditioned reflex that occurs with a certain irritation of the ternary nerve. It is assumed, but it is not known for sure, that the sharp excitation of the optic nerve, associated with the need to cover the eyes from strong light, is mistakenly transmitted to the ternary nerve, and sneezing occurs.
The light sneezing reflex is present in 20-30% of the population , is inherited.
Which gene is responsible for this and what may be associated with it is still unknown. wikipedia.org
The question has already been asked twice, perhaps someday experts will explain. The brain can redirect information from different nerves to some extent. There are experiments where the blind began to see with the help of hearing and touch. Those. in response to certain sounds, tingling sensations, the area of the brain responsible for vision was excited. Maybe this feature is triggered by mistake here too?
This phenomenon is called "Autosomal Dominant Involuntary Helio-Ocular Explosion Syndrome"
I am attaching a link to an article with a detailed and good explanation of this feature bbc.com