Defects of Vision and their Corrective Measures:

(i) Milky and Cloudy Eye Lens:
Defect: The eye lens becomes milky and cloudy due to the formation of a cataract.
Corrective Measure: Cataract surgery is the most common and effective treatment for this defect. During the surgery, the cloudy lens is replaced with an artificial intraocular lens (IOL). This improves vision clarity and restores normal vision.

(ii) Excessive Curvature of Eye Lens:
Defect: The excessive curvature of the eye lens results in the condition known as myopia or nearsightedness.
Corrective Measure: The corrective measure for myopia is the use of concave lenses. Concave lenses diverge the incoming light rays before they enter the eye, allowing the image to form on the retina instead of in front of it. This helps in focusing distant objects properly and correcting the vision.

(iii) Large Focal Length of Eye Lens:
Defect: When the eye lens has a larger focal length than normal, it leads to the condition called hypermetropia or farsightedness.
Corrective Measure: Hypermetropia can be corrected by using convex lenses. Convex lenses converge the incoming light rays, helping the eye lens to focus the image properly on the retina. This improves near vision and corrects the defect.

Explanation in Detail:

(i) Milky and Cloudy Eye Lens:
Cataract is a condition where the eye lens becomes milky and cloudy due to the clumping of proteins within the lens. This results in blurred vision, difficulty in seeing in bright light, and eventually, loss of vision. Cataract surgery is the most common and effective treatment for this defect. During the surgery, the cloudy lens is removed and replaced with an artificial intraocular lens (IOL) that allows light to pass through and focus properly on the retina. This improves vision clarity and restores normal vision.

(ii) Excessive Curvature of Eye Lens:
Myopia or nearsightedness occurs when the eye lens has excessive curvature or when the eyeball is too long. This causes the light rays to focus in front of the retina instead of directly on it, resulting in blurred vision for distant objects. The corrective measure for myopia is the use of concave lenses. Concave lenses diverge the incoming light rays before they enter the eye, which compensates for the excessive curvature of the eye lens and helps in focusing the image on the retina. This allows the individual to see distant objects clearly.

(iii) Large Focal Length of Eye Lens:
Hypermetropia or farsightedness occurs when the eye lens has a larger focal length than normal or when the eyeball is too short. In this condition, the light rays focus behind the retina, causing blurred vision for near objects. Hypermetropia can be corrected by using convex lenses. Convex lenses converge the incoming light rays, helping the eye lens to focus the image properly on the retina. This improves near vision and corrects the defect.

In conclusion, the defects of vision mentioned above can be corrected through appropriate measures such as cataract surgery, concave lenses for myopia, and convex lenses for hypermetropia. It is essential to consult an eye care professional for an accurate diagnosis and prescription of corrective measures.

1.catract
2.myopia
3.hypernetropia