Refractive error is the inability of parallel light rays to form a clear image on the retina after passing through the eye’s refractive action when the eye is not using accommodation, but is imaged in front of or behind the retina. It includes farsightedness, myopia and astigmatism.
There are many causes of refractive error, among which genetic factors are very important, of course, unreasonable eye use is not negligible, children are in the growth and development period, and do not pay attention to eye hygiene, such as reading, writing incorrect posture, or poor light, resulting in eye and book distance is too close, or reading for too long, or walking, reading in a car, etc. can cause excessive eye fatigue, contributing to refractive error.
Clinical manifestations
1.Myopia
Mild or moderate myopia, in addition to blurred vision of distant objects, there are no other symptoms, when working at close range, no adjustment or less adjustment can see the small target, but feel convenient, but in highly myopic eyes, the target distance is very close when working, both eyes are too inward collection, which will cause excessive use of the internal rectus muscle and visual fatigue symptoms.
2.Farsightedness
The visual acuity of farsighted eyes is determined by the level of their farsightedness and the strength of the regulating power. The total combination of hyperopia and vision is called total hyperopia, and the hyperopic eye is in a state of regulatory tension for a long time, so it is easy to have visual fatigue symptoms.
3.Sight fatigue symptoms
After reading, writing or working at close range for a long time, blurred handwriting or targets, dry eyes, heavy eyelids, a sense of fatigue, and eye pain and headache can occur, and after a few moments of rest, the symptoms can be significantly reduced or disappear, and such symptoms are usually most common in the afternoon and evening, and in severe cases, even nausea and vomiting can occur.
4. Astigmatism
Low refractive error may be asymptomatic, while slightly higher astigmatism may have reduced visual acuity, unclear vision at distance and near, seemingly with double vision, and often with symptoms of visual fatigue.
Examination
1.Subjective examination method
(1) According to the preliminary analysis of visual acuity examination to determine the refractive nature of the method.
(2) The method of insertion optometry.
(3) Crossed column lens and astigmatism correction device optometry method.
(4) Clouding method.
(5) Astigmatism table optometry method.
(6) Pinhole film and slit film examination method.
(7) Laser astigmatism chart method.
2.Objective examination method
(1) Direct ophthalmoscopy method.
(2) Retinoscopy method.
(3) Strip light inspection method.
(4) Corneometer.
(5) Automatic optometry, etc.
Differential diagnosis
1. Myopia should be differentiated from pseudomyopia.
2.Farsightedness should be differentiated from optic papillitis, myopia, presbyopia and orthopia.
Treatment
1.Myopia treatment
Mild and moderate myopia can be corrected with moderate concave lenses. High myopia often feels small, dizzy and difficult to see near objects after wearing a lens should be reduced as appropriate, or wear corneal contact lenses, but the latter can cause a series of corneal complications if not handled properly.
Myopia laser surgery is often referred to as “excimer laser surgery”, which uses an excimer laser to reduce the curvature of the cornea in the pupil area by refractively cutting the stromal layer under the corneal flap to correct myopia.
For myopia surgery, many people are afraid of slow recovery after surgery, which will delay their work, so many myopic patients want to know how fast or slow the recovery of myopia surgery is. The speed of recovery of vision from laser myopia surgery depends on age, refractive adjustment of the eyes and the degree of myopia before surgery.
In general, young people and those with low pre-surgical myopia will recover faster; in addition, vision from far away will recover earlier than vision from near (e.g. reading, looking at fine objects, etc.). Generally, after resting for one or two days after surgery, you can live and work normally. However, in the process of postoperative vision recovery, attention should be paid to eye hygiene so as not to cause eye fatigue and discomfort.
2.Farsightedness treatment
Farsightedness, if the vision is normal and there are no conscious symptoms, no treatment is needed. If you have symptoms of vision fatigue or your vision has been affected, you should wear a suitable convex lens for correction. Children with high degree of hyperopia, especially those with internal strabismus, should be fitted with lenses early. With the development of the eye, children’s hyperopia tends to decrease gradually, so they should be examined once a year in order to adjust the prescription of the glasses they wear at any time. In addition to convex lenses, corneal contact lenses can also be used for correction.
3.Treatment of astigmatism
Generally mild and asymptomatic people can not be treated, otherwise they should be corrected with columnar lenses, myopic astigmatism with concave columnar lenses, hyperopic astigmatism with convex columnar lenses.