Eye Defect and Its Correction: Presbyopia

Presbyopia is an age-related vision defect where a person loses the ability to focus on nearby objects. It usually develops around the age of 40 and continues to progress with time. It affects even those who have had perfect vision before or those who already have myopia (nearsightedness).

Presbyopia

Presbyopia occurs due to natural ageing and changes in the eye lens and surrounding muscles.

Main Causes:

• Loss of lens flexibility → The eye lens stiffens over time, reducing its ability to adjust focus.
• Protein changes in the lens → The composition of the lens proteins alters, making the lens less elastic.
• Weakening of ciliary muscles → The muscles around the lens lose their ability to contract and change the lens’s focal length.

As a result, the near point (least distance of distinct vision) shifts farther from the eye, making it difficult to focus on close objects.

• Difficulty reading or seeing objects up close.
• Needing to hold books or mobile screens farther away to see clearly.
• Frequent headaches due to eye strain.
• Eye fatigue while reading or performing close-up tasks.
• Increased sensitivity to glare and bright lights.

A. Spectacles and Contact Lenses

1. Progressive Lenses: They are multifocal lenses that provide clear vision at all distances (near, intermediate, and far). No visible separation between lens sections.

2. Bifocal Lenses: Lenses with two distinct sections:

• Upper part (concave lens) → Corrects nearsightedness (myopia).
• Lower part (convex lens) → Corrects farsightedness (hypermetropia).
• A visible line separates the two sections.

3. Reading Glasses: It is used only when reading or viewing close objects. It cannot be worn throughout the day.

4. Photochromic Lenses: These lenses automatically darken in sunlight to reduce glare, making them suitable for people sensitive to bright light.

5. Multifocal Contact Lenses: Available for those who prefer contact lenses over glasses. Monovision correction involves one eye fitted for distance vision and the other for near vision.

B. Surgical Treatments for Presbyopia

• Corneal Inlay Implantation: A surgical procedure that enhances depth of vision. It reduces dependency on glasses without affecting distant vision quality.
• LASIK and Other Laser Surgeries: Reshapes the cornea to improve near vision.