Uncover the "three primary colors" of the whites of your eyes: Why are your whites no longer bright? Scientific analysis of the discoloration of the whites of your eyes and the misunderstanding of whitening

Author: Bi Yanlong, Chief Physician and Professor of Tongji Hospital Affiliated to Tongji University

Shao Yuting, Doctor of Medicine, Tongji Hospital, Tongji University

Reviewer: Rong Ao, Chief Physician of Tongji Hospital Affiliated to Tongji University

The idiom "old and yellow" was often used to describe the whites of the eyes of older people, but nowadays, the whites of young people's eyes are also facing various problems. Some are full of "red bloodshot", some become dull and yellow, and a very small number of people have blue whites. In addition, many young people have begun to try various whitening products in their pursuit of beauty, and even researched methods to whiten the whites of the eyes. So, what is the reason for the changes in the "three primary colors" of red, yellow, and blue in the whites of the eyes? Are the methods of whitening the whites of the eyes circulating on the Internet scientific?

"Seeing through" the white of the eye: the conjunctiva and sclera are "good brothers"

The "white part of the eye" that we see in the mirror is actually composed of the transparent conjunctiva and the white sclera, with a gap between them called the Tenon's capsule (see Figure 1). Tiny blood vessels run between the conjunctiva and the sclera, providing them with necessary nutrients. When the conjunctiva or sclera is diseased, the color of the white of the eye will change, the most common being red, yellow, and blue.

Figure 1 Copyright image, no permission to reprint

The white of the eye turns "red" - the "struggle" of the conjunctival blood vessels

The redness of the white of the eye is usually related to the blood vessels of the conjunctiva, which manifests as a large number of "red blood streaks" or large "red blood clots" in the white of the eye. There are microvessels in the normal white of the eye, but they are difficult to detect with the naked eye. However, in the following three common abnormal conditions, the blood vessels that nourish the conjunctiva will dilate or bleed, causing the white of the eye to turn red:

Figure 2 Copyright image, no permission to reprint

When the eyes are overused, the demand for nutrients increases, causing blood vessels to dilate to accelerate blood flow and nutrient exchange. Short-term overuse of the eyes can cause "eye fatigue", and the "red blood streaks" will gradually disappear after a period of rest; long-term overuse of the eyes may develop into dry eye syndrome, and the "red blood streaks" will only disappear after a long period of rest and medication.

When the conjunctiva is infected by bacteria or viruses or has an allergic reaction, it will cause an inflammatory response in the body, leading to dilation of the conjunctival blood vessels, i.e. conjunctivitis. This may be accompanied by symptoms such as increased eye secretions, foreign body sensation, and itchy eyes. At this time, a doctor needs to determine the cause based on the symptoms and signs, and take appropriate eye drops for treatment in order to improve the "red blood streaks".

When large "red blood clots" appear in the eye, if it does not affect vision and is painless, it is mostly subconjunctival hemorrhage. This is usually caused by the rupture of microvessels in the eye due to greater external force (such as severe coughing, sneezing, lifting heavy objects, etc.), and blood enters the subconjunctival tissue space. Generally, it will gradually disappear within 1 to 2 weeks without special treatment. If subconjunctival hemorrhage occurs repeatedly, systemic disease examination is required.

The white of the eye turns "yellow" - the pigment "rendering" of the conjunctiva and sclera

There are usually two manifestations of yellowing of the whites of the eyes: one is overall uniform yellowing, which occurs in the sclera; the other is localized appearance of yellow, brown, or brown spots or patches, which occurs in the conjunctiva.

When the sclera turns yellow evenly, the first thing to consider is whether a large amount of foods rich in beta-carotene (such as carrots) have been consumed recently. Intake of a large amount of beta-carotene (about 2 carrots) every day can cause yellow sclera within 25 to 42 days. If this is the case, just stop eating foods rich in beta-carotene, and the yellow color will disappear after 2 to 6 weeks. If it is not for the above reasons, it is recommended to go to the hospital immediately to check liver function, which may be caused by liver disease causing increased bilirubin in the body. At this time, the patient may also experience symptoms such as yellow skin and yellow urine, which require timely treatment.

When yellow, brown, or brown spots or patches appear locally on the conjunctiva, the most common ones are blepharoplasty, conjunctival pigmentation, pterygium, and pigmented nevus. These are usually caused by abnormal accumulation of pigments due to stimulation of the eyes by wind and sand, strong light, chronic inflammation, etc. It is recommended to wear sunglasses and goggles in daily life to protect the eyes, and to seek timely treatment in case of acute infection to prevent and delay the occurrence and development of the above diseases. Most blepharoplasty, conjunctival pigmentation, and pigmented nevus only affect the appearance, but do not threaten vision and health. The development of pterygium is also very slow, but it is necessary to be vigilant: pigmented nevus that appear after the age of 50 and another larger range of conjunctival brown changes (clinically called "primary acquired melanosis"), if the area continues to increase, especially the latter, is very likely to develop into malignant conjunctival melanoma, which is potentially fatal.

The white of the eye turns "blue" - the pigment of the sclera "camouflage"

The blue color of the white of the eye mainly occurs in the sclera. There is another layer of tissue below the sclera called the uvea. Infants under 6 months old have a light blue white eye because the collagen structure of the sclera is not yet fully developed and the sclera is thin, so the uvea below can be seen. As the age increases, the sclera will gradually thicken and turn white. When the child is over 6 months old, if the blue color of the sclera deepens, it may indicate that the child has osteogenesis imperfecta, iron deficiency anemia and other diseases, and needs to seek medical attention in time. In addition, if certain drugs (such as minocycline) are taken for a long time, the metabolites of the drugs will form insoluble complexes with melanin, iron or calcium and deposit in the sclera, resulting in blue-gray deposits. This pigmentation generally disappears gradually after stopping the drug.

Learn about the three primary colors of the whites of the eyes and seek beauty rationally to resolve controversy

On the Internet, we can see many "magic tools" that can instantly remove "redness" and "yellowness" and whiten the whites of the eyes, such as some eye washes and eye drops. What we want to emphasize here is:

Figure 3 Copyright image, no permission to reprint

All products that have the effect of instantly removing "redness" have added vasoconstrictor ingredients and only treat symptoms. After the effect of the drug wears off, the vascular congestion will return to normal or even worse. Long-term use will also affect vascular elasticity and may cause high blood pressure. Therefore, the elderly or people with cardiovascular and cerebrovascular diseases should use such products with caution. In the case of red eyes, we should take appropriate intervention measures based on the above-mentioned cause analysis to achieve both symptomatic and root cause treatment.

There is no clear clinical research evidence to prove that eye drops can treat yellowing of the whites of the eyes. Many patients mistake the yellow spots on the surface of the conjunctiva for the "yellow spots" of the fundus (the two are not the same concept), leading to drug misuse. In addition, most eye drops contain preservatives, and long-term use will damage the corneal epithelium. If combined with dry eye syndrome, it is recommended to use preservative-free artificial tears as daily care.

Normal, healthy whites of the eyes are not the absolute white shown in photos on the Internet, which are often processed with filters. Therefore, we should not over-pursue whitening of the whites of the eyes and abuse eye drops.