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NEET Past Questions And Disscussion Part 2
1. Why is canthal incision not taken beyond lateral canthus of the eye?
- Cosmetic reason
- Prevent lymphatic drainage obstruction
- To Prevent ectroption
- Avoid damage to facial nerve
ANSWER b
Complication of lateral canthotomy
- Mechanical damage of the eye (eg, to the lateral rectus muscle, lacrimal gland, or lacrimal artery) or lids
- Hemorrhage
- Infection
- The urgency of the procedure, combined with traumatic distortion of the anatomy and possible unfamiliarity with the procedure by nonophthalmologists, may increase the risk of iatrogenic injury to the eyeball.
Step-by-Step Description of Lateral Canthotomy
- All preliminary steps should be done as quickly as possible, including rough estimation of visual acuity, inspection of the globe, and sometimes a simple cleaning and irrigation of the lateral canthus area.
- Place all your instruments on a tray near the head of the bed, so everything is within easy reach and you do not have to ask for assistance.
- Prepare the skin with an antiseptic agent such as povidone iodine or chlorhexidine; do not allow the antiseptic to enter the eye. Drape the area.
- Inject 1 or 2 mL of local anesthetic containing epinephrine into the lateral canthal incision site.
- Use a needle driver or hemostat to crush the tissue from the lateral canthus to the rim of the orbit, for about 20 seconds to 2 minutes. Crushing this tissue helps minimize bleeding and makes it easier to see where to cut when there is extensive traumatic edema.
- Use iris scissors to cut from the lateral canthus to the rim of the orbit, about 1 to 2 cm (canthotomy).
- Cut the inferior and sometimes both crus of the lateral canthal ligament (cantholysis). Most experts recommend starting with the inferior crus. Lift the lateral portion of lower eyelid. With the scissors pointing away from the globe, identify and cut the inferior crus. “Strumming” with the scissors may help identify the inferior crus. If the tendon is still intact, you will feel a twanging like a plucked string.
- Next, some experts recommend routinely cutting the superior crus. Others recommend reassessing for relief of orbital compartment syndrome (OCS—eg, by measuring intraocular pressure) and cutting the superior crus only if OCS persists.
- To cut the superior crus, lift and expose the underside of the lateral upper eyelid. Check whether the superior crus tendon has been cut by strumming across it with the scissors.
- If the tendon is still intact, cut it. Cutting the tendon loosens the eyelid and relieves pressure on the eye even more.
When cutting the inferior crus, aim inferoposteriorly toward the lateral rim to avoid injuring the levator muscle, lacrimal gland, and lacrimal artery, which are located superiorly
2. Parkland formula is represented by which calculation:
- Total body Surface area burnt x body weight/2
- Total body Surface area burnt x body weight/4
- Total body Surface area burnt x body weight x 2
- Total body Surface area burnt x body weight x 4
ANSWER d
3. Thermoluminescent dosimeter works on the principle of:
- Conversion of radiation into light
- Conversion of radiation into heat
- Conversion of radiation to light upon heating
- Conversion of energy to light
ANSWER c
Luminescent dosimeters are crystal structures which are able to trap and store energy when irradiated. This energy is later released via luminescence in the form of visible light. Measurement of emitted light may be used to determine the dose delivered to the dosimeter.
Dose Measurement
- Incident ionizing radiation creates an electron-hole pair in the crystal structure.
- The liberated electron is promoted to the conduction band and migrates to the electron trap. At the same time the hole migrates along the valence band to a hole trap.
- Energy (in the form of heat for a TLD or light for an OSLD) is imparted to the electron and hole allowing them to escape their traps. This causes the electron-hole pair to recombine at a luminescent center and release light.
- Emitted light is measured by a photomultiplier tube or camera (CCD or CMOS). This light is used to determine absorbed dose.
4. A 5-year-old patient presents with a root stump of tooth #75 which is painful. What is the treatment?
- A Extract 75 under local anesthesia
- A Extract 75 under local anesthesia followed by distal shoe space maintainer
- Do root canal therapy of root stump of 75 and put SS crown
- Give antibiotic and send back
ANSWER b
Distal shoe space maintainer
This appliance is called a distal shoe space maintainer or a distal extension space maintainer. It is used to prevent first permanent molars from moving mesially with the premature loss of second primary molars. The example shown is a crown with a distal extension segment soldered to the crown.
5. Which of the following is called Antioxidant vitamin?
- Tocopherol
- Vitamin A
- Thiamine
- Cyanocobalamin
ANSWER a
It's also known as tocopheryl acetate, tocopherol acetate, or vitamin E acetate. Vitamin E is known for its antioxidant properties. Antioxidants help to protect your body from damaging compounds called free radicals.
