Match List I with List II and select the correct answer using the code given below the Lists : List I (Disease) A. Hypermetropia B. Presbyopia C. Myopia D. Cataract List II (Remedy) 1. Concave lens 2. Bifocal lens 3. Surgery 4. Convex lens Code : A B C D
- (a)4 2 1 3
- (b)4 1 2 3
- (c)3 1 2 4
- (d)3 2 1 4
Correct — A, the code 4 2 1 3. Hypermetropia is long sight, in which the eye brings a nearby object to a focus behind the retina, so it needs extra converging power and is corrected by a convex lens, item 4. Presbyopia is the age-related stiffening of the eye lens that costs the eye its power of accommodation, so the same person needs one power for distance and another for reading — a bifocal lens, item 2, carries both in one piece. Myopia is short sight, in which a distant object is focused in front of the retina, and a diverging concave lens, item 1, pushes that focus back on to the retina. A cataract is not a focusing error at all but a clouding of the eye lens itself, and the remedy is surgery, item 3, in which the clouded lens is replaced by an artificial one.
- (b)4 1 2 3 — It keeps hypermetropia with the convex lens and cataract with surgery, but swaps the two remaining pairs — it hands presbyopia a concave lens and myopia a bifocal. A concave lens only weakens the eye's converging power, which does nothing for the loss of accommodation that presbyopia is.
- (c)3 1 2 4 — It sends hypermetropia to surgery and cataract to a convex lens. Long sight is a refractive error that a lens corrects, while a cataract is an opacity in the lens that no spectacle power can see through.
- (d)3 2 1 4 — The middle two pairs are right, but the outer two are exchanged: hypermetropia is given surgery and the cataract a convex lens. That reverses the one distinction the question is built on — a defect of focusing versus a defect of transparency.
Three of the four conditions listed are focusing errors and one is not. In myopia the eyeball is too long or the lens too strong, so parallel rays from a distant object meet in front of the retina and a diverging (concave) lens is added to move the focus back. In hypermetropia the opposite holds and a converging (convex) lens is added. Presbyopia is the loss of accommodation with age, so the eye can no longer change its own power between distance and near work, and a bifocal supplies two powers in one lens. A cataract is an opacity of the crystalline lens, treated by surgically removing it and implanting an artificial intraocular lens.
The quickest way through a four-pair match is to fix the pair you are surest of and let the code do the rest. Cataract to surgery is that pair, and only options (a) and (b) place surgery against D. Between them, decide hypermetropia — long sight needs converging power, so A must be the convex lens, item 4 — and both still survive. The tie-breaker is myopia, which is corrected by a concave lens, and only option (a) gives C the number 1.
- Myopia is corrected with a concave (diverging) lens; hypermetropia with a convex (converging) lens.
- Presbyopia is a loss of the eye's power of accommodation with age, which is why a bifocal lens with separate distance and near portions is prescribed.
- A cataract is a clouding of the eye lens, so it is treated surgically rather than with spectacles.
- Accommodation is the change in the eye lens's focal length brought about by the ciliary muscles.
Reading down the four rows gives A-4, B-2, C-1, D-3, which is option (a).
- Reversing the two lens corrections — myopia takes concave, hypermetropia takes convex.
- Treating presbyopia as just another name for hypermetropia; the first is a loss of accommodation with age, the second is a refractive error that can appear at any age.
- Assuming every eye complaint can be corrected with spectacles — a cataract cannot.
NDA asks either for the corrective lens of a named defect or, as here, for the whole defect-to-remedy match in code form.
An air bubble in water will act like a
- (a) convex mirror
- (b) convex lens
- (c) concave mirror
- (d) concave lens
Answer(d) concave lens
Tests the same idea from the other side — what makes a lens diverge rather than converge light, which is exactly why myopia takes a concave lens.
Myopia is a defect in human vision where an image of a
- (a) nearby object is focused beyond the retina.
- (b) nearby object is focused before the retina.
- (c) distant object is focused before the retina.
- (d) distant object is focused beyond the retina.
Answer(c) distant object is focused before the retina.
Fixes the one pairing that decides this match, by defining myopia in terms of where the image lands.
- practice — not a real PYQ
A person cannot see distant objects clearly. The defect and its correction are
- (a)hypermetropia, convex lens
- (b)myopia, concave lens
- (c)presbyopia, bifocal lens
- (d)cataract, surgery
Answer(b) myopia, concave lens — blurred distance vision means the image forms in front of the retina, which a diverging lens corrects.
- practice — not a real PYQ
A bifocal lens is prescribed mainly for
- (a)cataract
- (b)colour blindness
- (c)presbyopia
- (d)night blindness
Answer(c) presbyopia — the ageing eye loses accommodation, so one lens must carry a distance power and a near power.