What is aphakia and what is its treatment?

Aphakia is the term used when the lens is absent from the eye. So it must be replaced by an artificial lens. Know the therapeutic options.

Last update: September 13, 2022

The lens is a transparent structure in the eye that serves as a lens. allowing light rays to enter and strike the retina to focus images. Aphakia is the medical term for the absence of the lens.

There are several reasons why this structure is not present in the eye. The most frequent is secondary to removal due to the presence of cataracts.

For its part, congenital aphakia is a very rare entity, which is frequently associated with other structural alterations in the newborn eye. That is why a general inspection of the eyes at birth is necessary to notice any problems. It could mean visual limitation or even blindness for the rest of life.

lens function

The transparency of the lens is essential to allow light to enter the eye. In the same way, it is its main function: accommodation.

With this last term is known the ability of the lens to change shape, depending on the visual need. Thus, it is possible to focus the light beams on the retina.

The lens takes on a nearly spherical shape for near vision and a semi-flat shape for viewing objects in the distance.

In aphakia, as the lens is absent, accommodation is not possible. and light rays enter without a focus. This causes altered and blurred vision which, depending on whether the condition affects one or both eyes, can also be associated with other optical problems.

What are the causes of aphakia?

In intrauterine life, disturbances in the induction of lens precursor structures are a rare cause of aphakia. These children often have other eye defects, such as aniridia or absence of iris.

In contrast, the most common cause of aphakia in adults is cataract surgery. In it, the opaque lens is removed to avoid visual limitations.

Cataract correction: main cause of aphakia

Cataracts are opacities that appear in the lens, limiting the entry of light towards the retina. These cloudy spots can affect one or both eyes and their location on the lens varies.

Although there are multiple causes, in the newborn they are usually secondary to maternal infections during pregnancy. Similarly, genetic alterations and chromosomal abnormalities are causes as well.

In contrast, in the elderly, lens opacities appear as a result of the aging process. Other causes of cataracts, both in children and adults, are those of traumatic or metabolic origin or those related to the use of drugs (corticosteroids). Also, aphakic vision can be the result of lens dislocation or dislocation.

Cataracts can be large, with great visual impairment, or smaller, with a progressive evolution.

Therapeutic options in aphakia

The goal of aphakia correction is Replace the missing natural lens with an artificial one. Although intraocular lenses (IOLs) seem like the most logical option, their usefulness depends on the age of the patient.

In the adult, this is the ideal treatment in most cases. However, in children other considerations must be taken.

Glasses

Frame lenses continue to be useful in correcting aphakia, especially in pediatric patients with bilateral involvement. In children under 2 years of age, the choice is usually single vision glasses. After that age, bifocal segments are added to improve distance vision.

Aerial lenses are an attractive option for parents who do not feel comfortable handling contact lenses in their children. Either because of their own visual problems or because of difficulty in placing them.

The real advantages of glasses is that they are cheaper than contact lenses and provide protection against ultraviolet (UV) rays. In fact, there are some materials that darken in the presence of light, having the added benefit of minimizing light sensitivity.

However, they are thick and heavy, which is why they are considered unaesthetic. Similarly, as they tend to magnify images, they have a psychological and social impact on the patient.

With this type of glasses, the visual field is diminished and objects may appear and disappear in front of the eyes. In addition, they are not useful in unilateral aphakia or when the differences in magnification between the two eyes is great. This is because they do not allow the development of binocular vision, generating amblyopia and strabismus.



Aphakic contact lenses

Contact lenses are a very useful resource in visual rehabilitation in patients of any age. Likewise, they can be used in cases of affection of only one eye or in people with bilateral aphakia.

The biggest disadvantages they present are their high cost and the constant need for replacement, due to the growth of the eye in the first years of life. Placement can be difficult for some parents.

Similarly, the occasional loss of the lens is an additional problem to be aware of. Generally, in children with monocular aphakia, it is recommended that the fellow eye be occluded to prevent the development of visual disturbances.

There are rigid or flexible lenses on the market that have shown good tolerance.

Similar to what happens with frame glasses, in young children some diopters are added to increase the focus of near vision. Then, depending on the patient’s follow-up, it is decided to switch to bifocal lenses, which usually occurs between 2 or 3 years of age.

Some parents prefer to go to the consultation every month so that the contact lenses are replaced by a specialist. It is another possibility.



Intraocular lenses (IOLs)

Intraocular lens implants are an attractive option for rehabilitating vision in older children and adults. On the contrary, the technical problems faced by the surgeon, both in choosing the appropriate intraocular lens in young children and the high risks of subsequent complications, make it the least viable option for these patients.

With technological advances, the recommended age has decreased.

The main study that followed the treatment of aphakia in childhood, The Infant Aphakia Treatment Study (IATS), was performed with patients who did not have another structural abnormality in the eye. Therefore, considerations in children with additional conditions should be evaluated by an experienced team.

The intraocular lens implant does not eliminate the need to wear glasses. There are refractory changes that must be corrected after surgery and it is common to resort to glasses.

Likewise, the main complications to take into account with IOLs are the development of glaucoma and opacification of the visual axis. Not to mention the surgical difficulties dependent on the condition of each eye.

The placement of an IOL is an increasingly common practice. However, it is still a surgery with its risks.

Follow-up: the key to success in aphakia

It is vitally important that parents understand that cataract surgery is only the first step for the visual rehabilitation of the child. The cooperation of adults is essential for the success of the approach to aphakia.

During the first years, check-ups are regular and frequent, but follow-up of these patients should be maintained throughout life. Some of the consultations will have to be carried out under sedation to allow a thorough review in young children.

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