Aphakia is the absence of the
lens
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
of the
eye, due to surgical removal, such as in
cataract surgery
Cataract surgery, also called lens replacement surgery, is the removal of the natural lens (anatomy), lens of the human eye, eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artific ...
, a
perforating wound or
ulcer
An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughin ...
, or
congenital
A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...
anomaly. It causes a loss of ability to maintain focus (
accommodation), high degree of farsightedness (
hyperopia),
and a deep
anterior chamber. Complications include detachment of the
vitreous or
retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
, and
glaucoma.
Babies are rarely born with aphakia. Occurrence most often results from surgery to remove a congenital
cataract
A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...
. Congenital cataracts usually develop as a result of infection of the fetus or genetic reasons. It is often difficult to identify the exact cause of these cataracts, especially if only one eye is affected.
People with aphakia have relatively small
pupils and their pupils dilate to a lesser degree.
Causes
Surgical removal of a lens, mainly in cataract surgery, is the most common cause of aphakia.
Spontaneous traumatic absorption or congenital absence of lens matter is rare.
Traumatic subluxation or dislocation of a lens may cause it.
Signs and symptoms
* Hypermetropia: Without the focusing power of the lens, the eye becomes very
farsighted.
* Loss of accommodation: Since the lens and its
zonules are responsible for adjusting the focus of vision to different lengths, patients with aphakia will have a total loss of
accommodation.
* Defective vision: High degree hypermetropia and total loss of accommodation cause defective vision for both distance and near.
*
Cyanopsia: Absence of lens cause cyanopsia or blue vision.
Some individuals have said that they perceive ultraviolet light, invisible to those with a lens, as whitish blue or whitish-violet.
* Erythropsia: Sometimes, objects appear reddish.
* Deep anterior chamber: Since the lens is absent, anterior chamber will be deep.
*
Iridodonesis:
Iridodonesis is the vibration or agitated motion of the iris with eye movement.
* Purkinje test shows only two images; the reflection from anterior and posterior corneal surfaces.
*
Iridectomy mark may be seen in surgical aphakia.
*
Astigmatism: With-the-rule astigmatism due to corneal wound healing may occur in surgical aphakia, mainly after
intracapsular cataract extraction or
extracapsular cataract extraction.
Complications
Main complications of surgical aphakia include:
* Spectacle intolerance: Due to image
magnification (up to 30%),
optical aberration, prismatic effect and roving ring scotoma, spectacles are not well tolerated by aphakic patients.
Due to
unequal refractive power between the eyes, wearing spectacles with single-eye aphakia may cause
double vision.
* Glaucoma: Secondary angle closure glaucoma may occur due to vitreous prolapse.
* Retinal detachment
* Aphakic bullous keratopathy
Treatment
Aphakia can be corrected by wearing
glasses or
contact lenses, by
artificial lens implantation, or by
refractive corneal surgeries.
Eyes with artificial lenses are described as "
pseudophakic".
Etymology
From
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
''a-'', privative prefix + ''phakós'',
lentil, anything shaped like a lentil, e.g. a lens, via
New Latin.
[aphakia. (n.d.) Farlex Partner Medical Dictionary. (2012). Retrieved April 13, 2016 from http://medical-dictionary.thefreedictionary.com/aphakia]
References
External links
{{Congenital malformations and deformations of eye, ear, face and neck
Congenital disorders of eyes
Disorders of lens