In a cohort study to study association between factor

66. In a cohort study, to study association
between factor and disease, the risk ratio
was calculated to be equal to 1. What
does this signifies?
a) There is no association present between the factor and the
disease
b) There is positive association between the factor and the
disease
c) There is negative association between the factor and the
disease
d) Data insufficient to comment
Correct Answer - A
Ans: A. There is no association present between the factor and
the disease
Estimation of relative risk (RR):
Direct measure (or index) of strength of association between
suspected cause and effect.
RR=1 - Indicates no association.
RR > 1 - Indicates positive association between exposure & disease
under study.
RR = 2 - Indicates incidence rate of disease is 2 times higher in
exposed group (compared with unexposed).
Important in etiological enquiries.

67. According to the WHO definition of
hearing loss, what is the value to classify
as profound hearing loss?
a) 61-71 dB
b) >81 dB
c) >91 dB
d) >101 dB
Correct Answer - B
Ans: B. >81 dB
(Ref:
)
According to the WHO (2008) definition of hearing loss, hearing
threshold in better ear >81 dB is classified as profound hearing loss.
WHO (2008) Classification of Degree of Hearing Loss
Hearing threshold in better ear (average of
500, 1000,
Grade of Impairment
0-25 No impairment
26-40 Mild° impairment
41-60 Moderate° impairment
61-80 SevereQ impairment
>81
Profound impairment
including

68.

Maximum contribution to the refractive power
of the eye is by which part of the eye?
a) Anterior surface of cornea
b) Posterior surface of cornea
c) Anterior surface of lens
d) Posterior surface of lens
Correct Answer - A
Ans: A. Anterior surface of cornea
Maximum contribution to refractive power of eye - By anterior
surface of cornea.
Cornea's anterior surface is approximately spherical with a radius of
curvature that is typically 8 mm.
This surface is responsible for about two-thirds of the eye's refractive
power.

69. What is the usual weight of rabbit used in
ophthalmological experiments?
a) 0.5-1 kg
b) 1.5-2.5 kg
c) 5-7 kg
d) 10-12 kg
Correct Answer - B
Ans: B. 1.5-2.5 kg
(Ref: Animal Models in Eve Research/ p188).
The usual weight of rabbit used in ophthalmological experiments is
between 1.5-2.5 Kg.
Laboratory Animals:
Laboratory Animals
Animal Weight
Rat 180-200 gm
Guinea Pig400-600 gm
Mouse 20-25 gm
Rabbit 1.5-2.5 Kg°
Hamster 80-90 gm