The difference between nearsightedness and farsightedness.

Written by Li Zhen Dong
Ophthalmology
Updated on September 26, 2024
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Myopia is characterized by clear vision up close and blurred vision at a distance; hyperopia is characterized by clear vision at a distance and blurred vision up close. The main difference between myopia and hyperopia is the issue with the eye’s axial length. In an unaccommodated state, when parallel light rays enter the eye and focus in front of the retina, it is called myopia; when they focus behind the retina, it is called hyperopia. Myopic glasses are concave lenses, while hyperopic glasses are convex lenses. When myopia or hyperopia occurs, it is important to rest, reduce close-up activities, avoid eye fatigue, use eyes properly, eat a light diet, adjust your attitude, have regular check-ups, and pay attention to vision health.

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Written by Deng Jiang Tao
Ophthalmology
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Does myopia correction rebound?

Will there be a rebound after myopia correction surgery? Generally, it relates to two aspects. The first is associated with your pre-surgery degree of myopia; the second relates to your habits in using your eyes after the surgery. Generally speaking, the higher the degree of myopia before the surgery, the more likely a rebound will occur. Roughly speaking, if your degree of myopia was above 700 degrees before the surgery, there's about a 20% to 30% chance of rebounding. However, a rebound does not mean it will return to the previous degree of over 700; typically, it might rebound by around 100 to 200 degrees. The second aspect is significantly related to your post-surgery visual habits. If, after the surgery, you frequently use computers, read documents, or use your phone, there’s a higher chance of experiencing some degree of rebound. Conversely, if your screen time is less, the proportion of myopia rebound tends to be smaller.

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Written by Zheng Xin
Ophthalmology
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What should I do if nearsightedness is inherited by my child?

Not all myopia is hereditary, but high myopia does have a genetic component. The occurrence of myopia is mainly related to genetic and environmental factors. If there are children in the family with a history of high myopia, they should develop good eye habits from a young age, or undergo genetic testing for high myopia. If myopia occurs, it can be corrected by wearing glasses, or by refractive surgery after reaching adulthood.

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Written by Tao Yuan
Ophthalmology
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Can people with high myopia and floaters undergo myopia surgery?

Patients with high myopia who experience floaters can also undergo myopia correction surgery to eliminate nearsightedness. However, symptoms of floaters will not improve after the surgery. The commonly used myopia correction surgeries include laser surgery and the implantation of a posterior chamber intraocular lens for aphakic eyes. Patients need to visit the ophthalmology department of a hospital for optometry, corneal topography, and A-scan ultrasound examinations. The type of surgery is then determined based on the condition of the eyes. Floaters are caused by the clouding of the vitreous body within the eye due to aging. They can be treated with oral medications to promote absorption. For example, currently, lecithin complex iodine tablets can be taken, but the absorption is slow, requiring patients to adhere to regular treatment. (Please follow the doctor's advice when taking medication.)

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Written by Wang Fang
Ophthalmology
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Can eye fatigue cause nearsightedness?

Eye fatigue can exacerbate myopia, and it is an important factor in worsening nearsightedness. When the eyes look into the distance, they are in a completely relaxed state, which does not cause or worsen myopia. Myopia occurs due to near-distance eye activities. Prolonged close-distance eye activities and working too closely can lead to chronic fatigue in the external eye muscles. When this happens, the eye axis is stretched and, over time, cannot fully return to its original state, resulting in the onset or worsening of myopia. Therefore, during daily eye use, it is essential to avoid excessive duration and too close distances to prevent fatigue and thus avoid worsening myopia.

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Written by Li Zhen Dong
Ophthalmology
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Will nearsightedness be inherited?

Myopia has a certain hereditary aspect, but it is mainly caused by improper use of the eyes. Myopia is characterized by clear near vision and blurred distant vision, primarily due to changes in the eye's axial length. After the onset of myopia, it is crucial to properly dilate the pupils and conduct an optometric examination to rule out false myopia and amblyopia. Currently, the main treatments for myopia are still corrective glasses or orthokeratology lenses. Surgical treatment can also be considered for individuals aged 20 to 45. Once myopia develops, proper eye usage should be practiced, reducing close-range activities to avoid eye strain, and regular follow-ups are advised.