APHAKIA

•  What is aphakia?

It is absence of crystalline lens in its normal position in the eyeball. It may be congenital absence of crystalline lens or acquired (surgical removal of lens as after cataract surgery). It creates a high degree of hypermetropia

• Causes 

1. Congenital absence of crystalline lens. 

2. Surgical aphakia, e.g. after cataract surgery 

3. Traumatic aphakia: Lens is expelled out due to some injury. 

4. Spontaneous absorption of lens may occur sometimes producing aphakia. 

5. Posterior dislocation of lens in the vitreous cavity. 

• Clinical Features: 

Patient complains of marked loss of vision for distance and near, as there is total loss of accommodation.

1. Surgical scar mark may be seen on the limbus. 

2. Anterior chamber is deep. 

3. Iris shows tremulousness (Iridodonesis) on the movement of the eyeball. 

4. Pupil is jet black in color. 

5. 3rd and 4th Purkinje images are absent. 

6. Fundus shows a small disk with indistinct disk margins. 

7. Retinoscopy shows high hypermetropia.

Treatment:

 It can be corrected by glasses, contact lens and intraocular lens implantation. Usually, a +10 DS lens along with a cylinder for induced astigmatism is required to correct aphakia in a previously emmetropic patient. However, each and every patient should be individually assessed by retinoscopy for the power of glasses required. Aphakic glasses have the advantage of being cheap, safe and easy method of rehabilitation of aphakia. However there are a lot of problems associated with use of these glasses. These are magnification of image by 30% thus totally unfit for unilateral aphakia as this causes diplopia. It also causes hand eye incordination, problems of spherical and chromatic aberration due to thickness of lens. Field of vision is limited. There is prismatic effect from edges of glass. Objects appear and disappear if the patient tries to see them by moving eyes, i.e. roving ring scotoma (Jack in box phenomenon). So patient should be advised to move his head instead of moving his eyes to look sideways. Cosmetically they are unacceptable especially in young persons. Somewhat better method is use of contact lenses. They are cosmetically acceptable with less magnification (7%), more suited for unilateral aphakia with wider and better field of vision. Spherical and chromatic aberrations are absent. However they are costly, difficult to wear especially for old bilateral aphakes. Very good personal hygiene is required.The best method of rehabilitation of aphakia is IOL implantation. It is fitted on the table during surgery. It can also be implanted later on as secondary IOL implantation. It has 1 to 2% magnification only, hardly appreciated by patient, no aberration, no prismatic effect. That is why they are becoming more and more popular. However special training needs to be given to the surgeon for good results and costly equipments are required for surgery. Another method of rehabilitation of aphakia is refractive corneal surgery. LASIK laser is the best modality. In this surgery corneal stroma is ablated with laser to alter its curvature and thus alter the power of eyeball. Keratophakia and epikeratophakia have still not gained popularity.

Does aphakia cause any complications?

Most people easily recovery from eye surgery, but there are a few possible complications.

Aphakic glaucoma

Having any kind of eye surgery can increase your risk of developing glaucoma. This happens when building pressure inside the eye damages your optic nerve. If left untreated, glaucoma can lead to vision loss. After having any kind of eye surgery, make sure you follow up with regular eye exams to check for glaucoma.

Retinal detachment

People who’ve had eye injuries or surgery also have a higher risk of developing a detached retina. The retina has visual receptors that change images into electrical impulses, which are sent to the brain. Sometimes the retina detaches and pulls away from the tissue that holds it in place.

Symptoms of a detached retina include:

• seeing spots or flashes of light
• loss of peripheral (side) vision
• color blindness
• blurry vision

Get immediate medical treatment if you think you have a detached retina because it can lead to total blindness without timely treatment.