Aphakia

Aphakia is the absence of the lens of the eye, due to surgical removal, such as in cataract surgery, a perforating wound or ulcer, or congenital anomaly. It causes a loss of accommodation, high degree of farsightedness (hyperopia), and a deep anterior chamber. Complications include detachment of the vitreous or retina, and glaucoma.

Babies are rarely born with aphakia. Occurrence most often results from surgery to remove congenital cataract. 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: Surgical removal of lens, mainly in cataract surgery is the most common cause of aphakia.
• Spontaneous absorption of lens: Traumatic absorption of lens matter is a rare condition.
• Congenital primary aphakia: Congenital absence of lens is a rare condition.
• Subluxation or dislocation of lens: Traumatic subluxation or dislocation of lens may cause aphakia. It may occur due to congenital problems also.

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 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 ICCE or ECCE.

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 high anisometropia, spectacle correction in uniocular aphakia may cause diplopia.
• Glaucoma: Secondary angle closure glaucoma may occur due to vitreous prolapse.
• Retinal detachment
• Aphakic bullous keratopathy

Treatment

Aphakia can be corrected by wearing glasses, contact lenses, artificial lens implantation, or refractive corneal surgeries. Eye with artificial lenses are described as "pseudophakic".

Etymology

Gr. a- alfa priv + phakos, lens, anything shaped like a lens