Amblyopia

Impaired vision.

Unilateral reduction in visual acuity, in which there is no apparent pathologic condition of the eye.

Reduced vision in an eye without a detectable organic lesion.

“Lazy eye,” the most frequent cause of visual impairment in preschool children.

A lack of normal vision without a structural cause. A common example is squint and other forms may be caused by the cyanide in tobacco smoke or by drinking methylated spirits.

Reduced visual acuity not correctable by refractive means and not attributable to obvious structural or pathological optical.

Amblyopia is a term used to describe a loss of vision in an eye that appears to be physically healthy. It is commonly known as lazy eye. Amblyopia can occur for a variety of reasons, including strabismus (crossed or turned eye), congenital cataracts, cloudy cornea, droopy eyelid, nearsightedness, farsightedness, or astigmatism. Amblyopia may occur in various degrees depending on the severity of the underlying problem. The visual system is fully developed between approximately the ages of 9 and 11. If it is caught early, amblyopia can be corrected, however, after age 11 it is difficult if not impossible to train the brain to use the eye normally.

A serious eye condition that may involve loss of sight in one eye.

Dimness of vision without detectable organic lesion of the eye.

Impaired vision that is unrelated to an ocular lesion and cannot be fully corrected with glasses; most likely cause is abnormal vision during developmental years.

Poor vision in one eye resulting from a failure to develop normal sight during childhood; commonly known as “lazy eye.” The brain’s center of vision usually develops from birth to age 6 or 7 years. If the brain’s visual center has not developed by then, vision may be permanently impaired.

Poor vision in one eye resulting from a failure to develop normal sight during childhood; commonly known as “lazy eye.” Amblyopia results from functional and structural abnormalities after birth. The brain’s center of vision usually develops from birth to age 6 or 7 years. If the brain’s visual center has not developed by then, vision may be permanently impaired. A newborn can see, but must learn to focus and to coordinate images from both eyes into a single, three-dimensional image. If vision in one eye is distorted, nerve connections between that eye and the brain fail to develop properly. The brain learns to ignore the distorted image and relies only on the better eye. The result is amblyopia or a failure to develop normal vision in the affected eye.

Poor sight, not due to any detectable disease of the eyeball or visual system. In practice this strict definition is not always obeyed. For example, in toxic amblyopia, caused by tobacco, alcohol, certain other drugs, and vitamin deficiency, there is a disorder of the optic nerve. The commonest type is amblyopia ex anopsia, in which factors such as squint, cataract, and other abnormalities of the optics of the eye (see refraction) impair its normal use in early childhood by preventing the formation of a clear image on the retina.

Defective vision for which no recognisable cause exists in any part of the eye. It may be due to such causes as defective development or excessive use of tobacco or alcohol. The most important form is that associated with squint, or gross difference in refraction between the two eyes. It has been estimated that in Britain around 5 per cent of young adults have amblyopia due to this cause.

Unilateral or bilateral decrease of best corrected vision in an otherwise healthy eye, commonly due to asymmetric refractive error or strabismus.

In the realm of ocular intricacies, a perplexing phenomenon unveils itself—a gradual decline in visual acuity, often confined to a solitary eye. Curiously, this diminishment manifests without any discernible structural aberrations within the ocular apparatus. It is as if an enigmatic veil obscures the clarity of sight, leaving behind a disconcerting puzzle for both patients and clinicians alike. Amidst the absence of tangible ocular anomalies, the quest to unravel this visual enigma unfolds, seeking answers to restore the precious gift of unhindered vision.

Amblyopia refers to a lasting impairment of visual acuity that typically does not involve any structural anomalies in the eye. In numerous cases, this condition arises from an interruption in the visual pathway connecting the retina to the brain. The term “amblyopia” may also be used to describe the diminished visual acuity caused by toxic or nutritional factors, such as in the case of tobacco-alcohol amblyopia.

In order for normal vision to develop in infancy and childhood, it is crucial that both retinas receive clear and corresponding visual images, allowing compatible nerve impulses to transmit from the eyes to the brain. When no images are received, the development of normal vision becomes unattainable. In cases where the images from each eye significantly differ, one eye is suppressed to prevent the occurrence of double vision.

The primary cause of amblyopia, often observed in young children, is a condition called squint, which involves the misalignment of one eye relative to the other. In these cases, the failure to generate normal retinal images can lead to amblyopia. Additionally, congenital cataract (opacity of the eye’s lens) present from birth, as well as significant or unequal focusing errors, such as uncorrected astigmatism in one eye while the other eye has normal vision, can also hinder the formation of clear retinal images. Toxic and nutritional amblyopia may occur due to damage to the retina and/or optic nerve.

The usual treatment for amblyopia due to squint is patching (covering up the good eye to force the deviating eye to function properly). Surgery to place the deviating eye in the correct position may be necessary. Glasses may be needed to correct severe focusing errors. Cataracts may be removed surgically. After the age of eight, amblyopia cannot usually be remedied.