Eye defects Astigmatism

Astigmatism (cylindrical defect) is a vision disorder caused by a defect in the curvature of the lens or cornea that causes distorted vision.

Astigmatism usually occurs from birth, but can also be caused by eye injury or complications from eye surgery. Astigmatism can cause headaches and tired eyes.

Cause.

Astigmatism is caused by the lens or cornea that is not smooth so that light entering the eye becomes out of focus when transmitted to the retina.

Types of astigmatism :

• Corneal astigmatism ➡ is caused by defects in the cornea.
• Lenticular astigmatism ➡ is caused by defects in the lens.
• Regular astigmatism ➡ when one side of the cornea is more curved than the other. Can be treated with the help of glasses or eye lenses.
• Irregular astigmatism ➡ when the cornea is uneven not only on one side, but across the surface of the cornea. This condition is due to an injury that leaves a wound on the cornea. Can be treated with the help of contact lenses, but not with glasses.

Astigmatism cases generally arise from birth, the cause is not known with certainty, but it is suspected:

• Genetic.
• Low birth weight or premature birth.
• Complications due to eye surgery.
• Corneal injury due to infection.
• The shape of the eyelids which disturbs the structure of the cornea.
• Keratoconus and keratoglobus : corneal conditions can change shape (bulging or thinning).

Myopia (hypermetropy / hyperopia) and farsightedness (myopia) can accompany astigmatism.

Symptoms.

• A vague or unfocused vision.
• Dizzy.
• Eyestrain.
• Sensitivity to light rays (photophobia).
• Difficult to distinguish colors that are located next to each other.
• Difficulty seeing the full picture (straight lines appear slanted).
• In severe cases of astigmatism, sufferers can experience double vision.

Diagnosis.

• Astigmatism is detected through routine eye examinations. Regular eye examinations are important, especially for newborns and children.
• Visual acuity test to determine the accuracy of vision of an object from a certain distance with a Snellen chart.
• Keratometer test to determine the condition of defects in the cornea by looking at how focused the light is transmitted by the cornea to the retina.
• A retinoscope is used to shine light into the patient's eye to assess the degree of visual accuracy.

Treatment.

• Astigmatism treatment aims to improve the quality of the patient's vision by using glasses, eye lenses or through eye surgery procedures using laser light.
• Astigmatism treatment using laser light aims to repair the tissue in the cornea of ​​the eye that is not curved as it should. The outer cell tissue that is on the surface of the cornea will be removed first before the laser beam is used to change the shape of the cornea and restore the eye's ability to focus light.

Some laser surgery procedures for the treatment of astigmatism :

• LASIK (laser-assisted in situ keratomileusis).
• LASEK (sub-epithelial keratomileusis laser).
• Photorefractive keractectomy (PRK).

Complications.

Astigmatism that occurs in one eye from birth can cause lazy eye or amblyopia. This condition occurs because the brain is used to ignoring the signals sent by the eye. Amblyopia can be treated if diagnosed and treated early on before the visual pathways in the brain are fully developed.