lens
A lens is a transmissive optical device which 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''), ...
cataract surgery
Cataract surgery, also called lens replacement surgery, is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract, and its replacement with an intra ...
, a
perforating
A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes collectively are called a ''perforation''. The process of creating perforations is called perfor ...
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 sloughing o ...
, or
congenital
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
anomaly. It causes a loss of accommodation, high degree of farsightedness (
hyperopia
Far-sightedness, also known as long-sightedness, hypermetropia, or hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blurred effect is due to incoming light being focused behind, i ...
), and a deep
anterior chamber
The anterior chamber ( AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. Hyphema, anterior uveitis and glaucoma are three main pathologies in this area. In hyphema, blood f ...
. Complications include detachment of the vitreous or
retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...
, and
glaucoma
Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...
.
Babies are rarely born with aphakia. Occurrence most often results from surgery to remove congenital
cataract
A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...
. 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
pupil
The pupil is a black hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black ...
s 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
''Cyanopsia'' is a medical term for seeing everything tinted with blue. It is also referred to as ''blue vision''. Cyanopsia often occurs for a few days, weeks, or months after removal of a cataract from the eye. Cyanopsia also sometimes occurs a ...
: 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 lens is absent, anterior chamber will be deep.
*
Iridodonesis Iridodonesis () is the vibration or agitated motion of the iris with eye movement. This may be caused by lens subluxation, the incomplete or partial dislocation of the lens; or by aphakia, the absence of a lens. The term originated from irido- ( la, ...
: 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
An iridectomy, also known as a surgical iridectomy or corectomy, is the surgical removal of part of the iris.Cline D; Hofstetter HW; Griffin JR. ''Dictionary of Visual Science''. 4th ed. Butterworth-Heinemann, Boston 1997.
*
Astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at nig ...
: With-the-rule astigmatism due to corneal wound healing may occur in surgical aphakia, mainly after ICCE or ECCE.
Complications
Main complications of surgical aphakia include:
* Spectacle intolerance: Due to image
magnification
Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in siz ...
(up to 30%),
optical aberration
In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. Aberrations cause the image formed by a lens to be blurred or distorted, with th ...
, prismatic effect and roving ring scotoma, spectacles are not well tolerated by aphakic patients. Due to high
anisometropia
Anisometropia refers to a condition when two eyes have unequal refractive power. Generally, a difference in power of one diopter (1D) or more is the accepted threshold to label the condition anisometropia. Patients can tolerate 3 D of anisomet ...
, spectacle correction in uniocular aphakia may cause
diplopia
Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...
.
* Glaucoma: Secondary angle closure glaucoma may occur due to vitreous prolapse.
* Retinal detachment
* Aphakic bullous keratopathy
Treatment
Aphakia can be corrected by wearing
glasses
Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or ...
,
contact lenses
Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic ...
Gr. ''a-'' alfa priv + ''phakos'', lens, anything shaped like a lensaphakia. (n.d.) Farlex Partner Medical Dictionary. (2012). Retrieved April 13, 2016 from http://medical-dictionary.thefreedictionary.com/aphakia