The film ‘Owl’ is a thriller that depicts the struggle of a blind acupuncturist who can only see at night to reveal the truth after witnessing the death of the crown prince. Actor Ryu Jun-yeol plays the role of a blind acupuncturist who can only see at night. He discovered “week blindness,” a condition that cannot be seen during the day and can only be seen dimly at night.
If you can’t see better during the day, we suspect blindnessㅣSource: Getty Image Bank
What causes day blindness, in which a clear night is better than a cloudy day?
A representative element that allows us to see something clearly is ‘light’. In the dark with little light, even the correct shape is difficult to distinguish. “Night blindness,” which we commonly know, refers to symptoms of difficulty seeing objects in dimly lit or dark places. The opposite concept is “week blindness”. Unlike night blindness, night blindness is more difficult to see during the day than at night.
The eyeball is made up of nine tissues. The cornea which refracts light together with the lens to see objects, the lens which refracts light with the cornea to see objects, the iris which regulates the amount of light entering the eye (pupil refers to the hole between the iris), protects the eye The sclera (commonly referred to as the white of the eye), the choroid (uvea) which blocks light from entering the pupil, the retina, which enables approximately 130 million photoreceptors to recognize light and see objects, recognize objects clearly and accurately and The macula that collects, the optic nerve that transmits the light information received from the retina and the macula to the brain and the vitreous body that fills a large area of the eye.
The iris, which regulates the amount of light, closes when too much light enters and the pupil constricts. Conversely, when the light is dim, the iris opens and the pupil dilates. Light reflected from objects is reflected back to the retina through the cornea and lens. At this time, if the lens becomes cloudy and the field of vision becomes cloudy, it is difficult to see the surroundings even if there is enough light. This symptom is called “week blindness”. A typical symptom of opacity of the lens is cataract. In other words, major blindness is one of the symptoms often seen in the early stages of cataracts.
Why does night blindness occur when the eyes are dark at night?
There is a difference between night blindness and day blindness, which we commonly know, by their causes. Night blindness is a condition in which you cannot see well at night and has various causes. Among these, representative causes are vitamin A deficiency, retinitis pigmentosa, and congenital non-progressive night blindness.
In order for our eyes to perceive light, the light must be detected by the photoreceptor and transmitted to the brain via the optic nerve. At this time, a visual substance called rhodopsin (a protein that detects red light in the retina of the eye) of the photoreceptor cell is broken down by light. Vitamin A is a necessary ingredient for rhodopsin production, and a lack of vitamin A can cause night blindness. Also, night blindness can occur due to retinitis pigmentosa – a progressive disease that occurs due to problems with photoreceptor function. It appears mostly in people in their teens and twenties and the cause is unknown, but it is known to be a disease caused by genetic abnormalities. Non-progressive congenital night blindness is a case of congenital night blindness, which is mainly caused by heredity.
Suspicion of cataract in case of major blindness
Unlike night blindness, which is caused by various causes, day blindness usually appears as an early symptom of cataracts. A cataract is a disease in which the lens of the eye becomes cloudy due to some cause, causing vision problems. It can be congenital due to genetic causes or rubella in early pregnancy, but it can also appear acquired due to aging, trauma, systemic disease, eye inflammation or toxins.
Cataract is the most common surgical procedure in Korea. According to the 2020 Major Surgery Statistical Yearbook announced by the National Health Insurance Corporation, the number of cataract surgeries was the highest at 702,621. It was followed by general spinal surgery (188,394 cases), hemorrhoid surgery (169,669 cases), cesarean section (146,427 cases), and cholecystectomy (86,274 cases). Cataract, a representative geriatric disease, is caused by changes in the protein structure of the lens during the aging process, and is also affected by the living environment, such as prolonged exposure to ultraviolet rays. It can also occur as a complication of diseases such as high blood pressure and diabetes. In recent years, with the increase in the use of digital devices such as smartphones and computers, cataracts have also increased in relatively young age groups.
Unlike usual, cataracts should be suspected if you have difficulty distinguishing objects during the day when there is enough light. Cataracts are not a disease that requires quick treatment, but as there may be differences in the rate and degree of progression, it is good to visit an ophthalmologist and get a detailed diagnosis if blindness occurs. In particular, if major blindness occurs in people over the age of 40, there is a high probability that the cataract is progressing. Severe blindness can make outdoor activities and indoor lighting difficult. If primary blindness is not treated, it can lead to a vicious cycle in which the pupil turns white in the final stage and, if left untreated, glaucoma occurs.
Cataracts and blindness should be prevented through lifestyle improvements…
Cataracts progress slowly without any specific symptoms and are easy to detect after symptoms worsen. Therefore, if major blindness occurs, an early symptom of cataracts, efforts are needed to slow the progression of the cataract.
The basic treatment for cataracts is surgery, but if it is caught relatively early, the progression of the cataract can be slowed by lifestyle changes. Since cataracts are mainly caused by eye aging, the best way to prevent aging is to reduce the use of electronic devices such as smartphones. If it’s difficult to reduce the time you use electronic devices for work or realistically, you should get into the habit of reducing eye strain from time to time.
UV rays also have a significant effect on eye aging. It is recommended that you wear sunglasses or bring a wide-brimmed hat or goggles to block the UV rays.
Additionally, taking eye nutrients containing astaxanthin, lutein, and anthocyanins can help prevent cataracts. In addition, keeping the indoor temperature and humidity at an appropriate level so that the eyes do not dry out, and living in bright light conditions is also a good habit to prevent eye aging and cataracts.
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