Amblyopia refers to the condition where the best-corrected visual acuity is below 0.9 (0.9 applies to those aged 5 and above; for those below 5 years old, the standard should be adjusted as follows: 0.8 for 4-year-olds, and 0.6 for 3-year-olds and younger). In femtosecond laser myopia surgery, amblyopia can be divided into two types: that formed with obvious organic lesions and that caused without obvious organic lesions.
(1) Strabismic Amblyopia: Patients either have strabismus or have had it in the past. Due to eye misalignment, double vision occurs. To eliminate or overcome the double vision caused by strabismus, the brain's visual cortex suppresses the visual impulses transmitted from the deviated eye. The macular function of the deviated eye is suppressed over a long period, leading to amblyopia. This type of amblyopia is a consequence of strabismus, secondary and functional. Therefore, appropriate treatment at an early stage may improve the vision of the amblyopic eye. However, there are some stubborn cases where, despite long-term treatment, there is little improvement in vision.
(2) Anisometropic Amblyopia: When there is a significant difference in refractive error between the two eyes, the clarity or size of the images formed on the maculae of both eyes differ greatly, making fusion difficult. The cerebral cortex then suppresses the image coming from the eye with greater refractive error, eventually leading to amblyopia over time. This type of amblyopia is functional and has the potential for vision recovery through treatment. Early correction of refractive errors could possibly prevent its occurrence.
(3) Deprivation Amblyopia: In infancy, if there is corneal opacity, ptosis, congenital cataracts, or even inappropriate occlusion of one eye, light cannot fully enter the eye, depriving the macula of that eye from receiving normal light stimulation. The development of visual function is inhibited, resulting in amblyopia. This kind of amblyopia not only causes low vision but also has a poor prognosis.
(4) Refractive Amblyopia: Mostly bilateral, this occurs in individuals with high refractive errors who have never worn corrective glasses. After wearing suitable glasses, vision gradually improves, but this process takes a relatively long time, generally requiring 2-3 years.
(5) Congenital Amblyopia: The exact pathogenesis is not yet fully understood. It might be due to small hemorrhages in the retina or visual pathway after birth, affecting the normal development of visual function. Some cases are secondary to nystagmus or total color blindness. The prognosis for this type of amblyopia is generally poor.
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