If you've ever worn contact lenses
There may be such an experience
It's hard to finish the day
But I found that my eyes were dry and astringent
There was even a faint hint of red blood
You might tell yourself
Maybe it's a whole day of crazy output on a computer screen
Let your eyes be overwhelmed
Just get a good night's sleep
But in fact, red eyes or dry eyes
It doesn't have to be overuse of the eyes
It may be related to your "contact lenses"
Let Dr. Tian Tai show us today
Contact lenses that do not fit
What will be done to our eyeballs?
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It starts with the "cornea" in the eye
The cornea is one of the main refractive media in the eyeball
Equivalent to a convex lens
You can also understand it as "the lens of the camera"
Cornea and lens
By concentrating light onto the retina
Let's see the world
And our eyes
Tears are secreted to maintain the cornea
Every blink of an eye
Tear fluids keep the surface of the cornea moist
Rinse and lubricate the corneal surface
Provides nutrients
And the most important point is
Tear fluids supply oxygen to the cornea through contact with air
Wear contact lenses
That's the equivalent of an extra wall
If this wall is airtight
Let the tear fluid not adequately deliver oxygen to the cornea
That would make the cornea chronically hypoxic
Once hypoxic
The eye will find a way to "save" the cornea
Capillaries proliferate at the edges of the cornea of the eye
Trying to oxygenate the cornea through the blood
These blood capillaries transport oxygen one more
The red blood of the white eyes increases
The eyes were red
A long time
Proliferative vessels may extend to the transparent center of the cornea
This is one of the factors that cause blindness in the eyes!
There is also a case of red eyes
The edge treatment of some contact lenses is not smooth
This increases the mechanical friction of the lens against the conjunctiva
This can also cause conjunctival congestion and reddening of the whites of the eyes
Severe or even "giant papillary conjunctivitis"
Except for "red eyes"
"Dry eyes" are also a common symptom of contact lenses
It is related to the moisturizing effect of contact lenses
Our cornea is covered with a layer of tear fluid called the tear film
There is a layer of grease on the surface of the tear film
It can envelop moisture and reduce moisture evaporation
But some contact lenses are put on after
Lens pores absorb fluid from the tear film
Causes insufficient tear film on the surface of the eye
At the same time, the lenses do not have water locking technology
Causes accelerated evaporation of moisture from the eyeball
Some contact lens products advertise themselves as having a high moisture content
In fact, this is not necessarily a good thing
Because once the moisture content is high
Coupled with the general water lock, it is easy to evaporate
The water in that tear
It will be sucked away and evaporated by contact lenses
It's a "loser"
So
High moisture content ≠ good moisturizing effect
Conversely, the eyes may be drier
If you do not pay attention to the habit of using your eyes, look at the electronic screen for a long time,
The number of blinks and decreased tear secretion
Then the problem is even worse
How to choose
A suitable pair of contact lenses
1. See through the oxygen
It is recommended to choose contact lenses made of silicone hydrogel
Or choose hydrogel contact lenses with an oxygen permeability greater than 24 (units) or 18 (units).
Remarks: There are two units of oxygen permeability,
单位 (cm/s)[mLO /(mL*mmHg)]
单位 (cm/s)[mLO /(mL*hPa)]
The two can be converted to each other *0.75 =
Of course, oxygen permeability is not as high as possible
The value reaches a certain level
The amount of oxygen to the cornea does not increase significantly
Instead, the lens material may be harder,
Poor elasticity affects comfort
So it's actually a matter of balance
2. Look at the water lock moisturizing technology
It is recommended to choose some of the main products with R & D strength of large brands
For example, technology that contains various moisturizing factors
It can make contact lenses lose moisture more slowly
Maintains the stability of the tear film
Reduce evaporation and avoid dry eyes
3. Look at the softness of the lenses
Bad contact lenses
Increases mechanical friction on the eyeball
Therefore, the softness and smoothness of the lens itself is very important
It is recommended before bulk purchase
Try on 1 to 2 times and choose a comfortable lens
Special Reminder:
Before choosing any contact lens, be sure to go to a regular hospital or optometry center to check your own degree, base arc size, and make a choice based on the ophthalmologist's advice.
If the astigmatism is high to a certain extent, it is recommended to choose astigmatism contact lenses.
This article is reviewed by experts
This article is co-authored by experts
Liu Jiaxing
Senior Optometrist
Bachelor of Optometry from Liaoning Ho Medical College
Jin Xin
Grade II optometry technician
Director of Shouyang Institute of Myopia Strabismus Amblyopia Prevention and Control
bibliography
Xie Peiying. Contact lens fitting technology[M]. People's Medical Publishing House, 2012.
[2] Ready. Contact lenses of the cornea[J]. People's Medical Publishing House, 2014.
Lü Fan. Contact lenses for optometry(for optometry)[M]. People's Medical Publishing House, 2005.
Planning and production
Planner: Yang Dafeng, Zhu Dakeng | Illustration: Made your own
Executive Producer: Feidi | Cover Source: Made your own