The movie ‘Owl’ is a thriller depicting 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. Learn about ‘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, let’s suspect blindnessㅣSource: Getty Image Bank
What is the cause of the occurrence of day blindness, where 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, it is difficult to distinguish even the proper form. ‘Night blindness’, which we commonly know, refers to the symptoms of difficulty distinguishing objects in dim light 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 that refracts light together with the lens to see objects, the lens that refracts light with the cornea to see objects, the iris that regulates the amount of light entering the eye (the 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) that prevents light from leaking into the pupil, the retina, which allows about 130 million photoreceptors to recognize light and see objects, recognize objects clearly and accurately and The macula that collects, the optic nerve that transmits light information received by the retina and 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 narrows. Conversely, when the light is low, the iris opens and the pupil dilates. Light reflected from objects is reflected on the retina through the cornea and lens. At this time, if the lens becomes cloudy and the field of view becomes cloudy, it is difficult to see the surroundings even though there is enough light. This symptom is called ‘week blindness’. A typical symptom of opacity of the lens is a cataract. In other words, main blindness is one of the symptoms often found in the early stages of cataract.
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, from their causes. Night blindness is a condition in which you cannot see well at night, and it has various causes. Among them, the 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 decomposed by light. Vitamin A is an ingredient necessary for the production of rhodopsin, and a lack of vitamin A can cause night blindness. In addition, night blindness can occur due to retinitis pigmentosa, a progressive disease that occurs due to problems with the function of photoreceptors. It mainly appears in people in their teens and 20s, and the cause is unknown, but it is known to be a disease caused by genetic abnormalities. Congenital non-progressive night blindness is a case of congenital night blindness, which is mostly caused by heredity.
Suspicion of cataract in case of main blindness
Unlike night blindness, which is caused by various causes, day blindness usually appears as an early symptom of cataract. A cataract is a disease in which the lens in the eye becomes opaque due to some cause, causing visual impairment. It may be congenital due to genetic causes or rubella infection in early pregnancy, but it may also appear acquired due to aging, trauma, systemic disease, inflammation in the eye, 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, as the use of digital devices such as smartphones and computers has increased, cataracts have also increased in relatively young age groups.
Unlike usual, cataracts should be suspected if you have difficulty distinguishing objects in the daytime when there is enough light. Cataract is not a disease that requires quick treatment, but since there may be differences in the speed and degree of progression, it is good to visit an ophthalmologist and get a detailed diagnosis if blindness occurs. In particular, if main blindness appears in people over the age of 40, there is a high probability that cataracts are progressing. Severe blindness can make outdoor activities as well as indoor lighting difficult. If primary blindness is left untreated, it can lead to a vicious cycle in which the pupil turns white in the final stage and if left untreated, glaucoma occurs.
Cataract and blindness should be prevented through lifestyle improvement…
Cataracts progress slowly without any specific symptoms and are easy to detect after the symptoms have worsened. Therefore, if main blindness, an early symptom of cataract, appears, efforts are needed to slow down the progression of the cataract.
The fundamental treatment for cataract is surgery, but if it is detected relatively early, the progression of cataract can be slowed down by lifestyle changes. Since cataracts are mainly caused by aging of the eyes, the best way to prevent aging is to reduce the use of electronic devices such as smartphones. If it is difficult to reduce the time of using electronic devices for business reasons or realistically, you should make it a habit to reduce eye fatigue from time to time.
UV rays also have a significant effect on aging of the eyes. It is recommended to wear sunglasses or bring a wide-brimmed hat or safety goggles to block UV rays.
In addition, taking eye nutrients containing astaxanthin, lutein, and anthocyanin 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 lighting is also a good habit to prevent eye aging and cataracts.
<저작권©언론사 하이닥, 무단 전재 및 재배포 금지>