Which of the following practices may lead to infection of the eye? Use of

Step 1: Analyze the question The question asks which practice can lead to an eye infection. The key idea is direct contact with the eye surface and hygiene.

Step 2: Explain the concept

• Convex, concave, and biconcave lenses are types of lenses used in spectacles (eyeglasses) to correct vision defects. They sit in a frame some distance from the eye, so they do not touch the eyeball and do not normally cause infection.
• Contact lenses are placed directly on the cornea. If they are not cleaned properly, are worn for too long, are shared, or are handled with dirty hands, bacteria, fungi, or protozoa can build up on them. This can cause conjunctivitis (pink eye), keratitis (inflammation of the cornea), or corneal ulcers.

Step 3: Work through the options

• A. Contact lenses: touch the eye directly and can carry germs. Possible cause of infection.
• B. Convex lenses: correct long-sightedness, worn in spectacles. Not in contact with the eye.
• C. Biconcave lenses: correct short-sightedness, worn in spectacles. Not in contact with the eye.
• D. Concave lenses: same as C. Not in contact with the eye.

Step 4: Answer The correct option is A. contact lenses.

Tip: In Biology, when a question asks about "infection" of the eye, look for the option involving direct contact or poor hygiene, such as contact lenses, sharing towels, or rubbing the eyes with dirty hands. Convex and concave lenses are Physics or optics topics and are mainly about correcting vision, not about infection.