Q-111. Corneal edema in hypoxic condition due to accumulation of
a) Lactate
b) Pyruvate
c) Glycogen
d) Carbon dioxide
Answer: Lactate
Explanation:
Stromal lactate accumulation can account for corneal edema osmotically following epithelial hypoxia.
Q-112. Which one of following is used in retinal sealing?
a) Co
b) SF6
c) Nitrous oxide
d) So2
Answer: SF6
Explanation:
Pneumatic retinopexy (PR) is an alternative to scleral buckling for the surgical repair of selected retinal detachments.
A gas bubble is injected into the vitreous cavity, and the patient is positioned so that the bubble closes the retinal break (s), allowing absorption of the sub-retinal fluid.
Cryotherapy or laser photocoagulation is applied around the retinal break(s) to form a permanent seal.
Sulfur hexafluoride (SF6) is the gas most frequently used for PR, followed by per-fluoro-propane (C3F8).
- Which of the following antibiotics can be used in the treatment of fungal kerato-mycosis?
a) Linezolid
b) Vancomycin
c) Silver sulphadiazine
d) Doxycycline
Answer: Silver sulphadiazine
Explanation:
Ocular anti-fungal agents:
Polyene anti-bacterial
Pyrimidines
Imidazole
Iodine and sulphadiazine
Important point:
Silver sulfadiazine is a topical antimicrobial agent with both antifungal and antibacterial activity and may also be useful in kerato-mycosis
Q-114. Which of the following topical agents causes hetero-chromia iridis?
a) Latanoprost
b) Prednisolone
c) Timolol
d) Olopatadine
Answer: Latanoprost
Explanation:
Heterochromia iridis occurs in several conditions:
Waardenburg syndrome
Fuchs hetero-chromic iridocyclitis
Melanosis oculi
Iris melanoma
Horner syndrome
Certain drugs, such as Latanoprost
Q-115. Evisceration of eye is not done in
a) Malignancy
b) Pan-ophthalmitis
c) Trauma
d) Hemorrhage
Answer: Malignancy
Explanation:
Indications of evisceration:
Pan-ophthalmitis
Expulsive choroidal hemorrhage
Bleeding anterior staphyloma
Severe traumatic injury
Q-116. Vitreous humor has high concentration of what compared to blood
a) Glucose
b) Sodium
c) Potassium
d) Ascorbate
Answer: Ascorbate
Explanation:
Ascorbic acid (AA) accumulates in vitreous at a concentration several times higher than in plasma.
It has been suggested that AA may serve as an antioxidant that protects ocular tissues from free radical attack.
Important points:
Composition of aqueous is similar to plasma except that it has high concentration of ascorbate, pyruvate and lactate; and low concentration of protein, urea and glucose.
Q-117. Corneal sensation is lost in which nerve palsy
a) Naso-Cilliary nerve
b) Supra-trochlear nerve
c) Infra-trochlear nerve
d) Infra-orbital nerve
Answer: Naso-Cilliary nerve
Explanation:
Loss of sensation in naso-ciliary nerves which are branch of ophthalmic division of 5th cranial nerve is of great importance.
Loss of sensation in cornea abolishes corneal reflex leaving the cornea unprotected and can lead to ulcer formation on cornea.
Q-118. High molecular weight proteins in cataractous lens seen only in humans
a) HM 1 and 2
b) HM 2 and 4
c) HM 3 and 4
d) HM 2 and 3
Answer: HM 3 and 4
Explanation:
The high molecular weight fractions isolated from nuclear cataracts:
Fraction HM3 and HM4 are only found in cataractous lens.
Q-119. Universal marker of limbal stem cells
a) Elastin
b) Keratin
c) Collagen
d) ABCG2
Answer: ABCG2
Explanation:
At the corneo-scleral junction in an area known as the limbus, there is a population of limbal epithelial stem cells.
Limbal epithelial stem cells share common features with other adult somatic stem cells including small size and high nuclear to cytoplasmic ratio.
They also lack expression of differentiation markers such as cyto-keratins 3 and 12.
ABCG2 has been proposed as a universal and conserved marker for stem cells from a wide variety of tissues.
Q-120. Multifocal ERG impulse records from
a) Rods
b) Ganglion cell layer
c) RPE layer
d) Macular cones
Answer: Macular cones
Explanation:
In patient with macular degeneration, the multifocal ERG technique is a useful tool to detect and quantify central cone function, especially in disease stages with no or subtle visible retinal changes.
Depending on the underlying disorder, patient with macular degeneration may show reduced and/or delayed central responses.