FRCS part 2 (15th, April 2009)
         

1. Munnerlyn’s formula for estimating needed central corneal ablation depth for LASIK.

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2. Apostilb – the luminance of a perfectly diffusing reflecting surface reflecting or emitting 1 lumen/sq m

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3. The atoms used in producing excimer lasers of 193nm – Argon Fluoride

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4. Laser light can be focused to a small spot unlike white light because it is –very highly monochromatic

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5. Idea pinhole aperture size – 1.2 mm

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6. Range of refractive errors that can be corrected with pinhole vision - -5D to +5D

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7. Diffractive effects of reducing pinhole size and subsequent effect on VA

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8. Pinhole VA will become WORSE  in a case of 

a. Corneal scarring

b. ARMD

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9. ‘Pumping’ refers to – exciting atoms in ground state to excited state

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10. What are the image characteristics of an object placed inside the focal length of a convex lens

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11. What are the image characteristics of a convex mirror x 2 – Virtual, upright, minified

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12. Operating microscopes are based on which optical principle – Astronomical Telescope

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13. BIO is based on what optical principle? – Astronomical Telescope

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14. If a patient’s pupil is not conjugate with the observer’s pupil, - the 

a. Peripheral fundus is dark

b. The whole image is dim

c. The whole image is blurred

d. The image is larger and blurred

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15. The image formed by a prism is – virtual, erect, displaced toward the apex

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16. Formula for projected post-operative K reading

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17. The Keratometer measures 

a. The refractive power of the cornea – wrong, it INFERS the refractive power of the central 3 mm of the FRONT surface of the cornea

b. The REFLECTIVE power of the surface of the cornea – Right answer

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18. The Keratometer – the formed image size is proportionate to the radius of the cornea

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19. Goldmann applanation tonometry – Dynes of pressure equivalent to mmHg x 10

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20. Goldmann applanation tonometry – 3.06 mm (size of applanated cornea when measurement taken)

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21. Ophthalmic USS – 8MHz

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22. Non contact axial length can be taken through

a. Partial coherence interferometry

b. High frequency uss

c. Scanning laser ophthalmoscopy

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23. A prism with a power of 1 prism dioptre – shifts an image one cm at one m away.

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24. Anisometropic aniseikonia can be reduced by – using combinations of contact lenses and spectacle lenses to produce Galilean telescopic effects

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25. Position of Phakic IOLS

a. Papillary plane

b. 2mm behind papillary plane

c. Gently touching the crystalline lens

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26. The human eye is equivalent to a simple magnifier of power – 60D

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27. A patient who is -13D myopic will have better best corrected VA with contacts rather than spectacle lenses because

a. Magnification effect of CLS as opposed to spectacle lenses – Right answer

b. Spectacle lenses induce prismatic effects – But in primary position through optical centre?

c. Spectacle lenses dirty easily

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28. A previously emmetropic aphakic eye is best corrected with a lens placed at

a. 15.7mm from eye

b. Pupillary plane

c. In contact with the eye

d. 2 mm behind the pupillary plane

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29. Streak retinoscopy: Scissors reflex  – part of pupil reflex showing WITH and another part showing AGAINST within the pupil 

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30. Streak retinoscopy: If the working distance were 67 cm, what working distance lens would you use? – +1.5D

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31. With the rule astigmatism can be corrected with a plus cylinder lens at – Axis 90

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32. Streak retinoscopy: If the observer were at the patient’s far point in streak retinoscopy and he moved forward, what would the pupil reflex be? – Against Movement

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33. Streak retinoscopy :If the observer were at the patient’s far point – all the light from the patients eye would enter the observer’s eye and illumination would be uniform and not move

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34. Streak retinoscopy and pupil reflex if streak is not aligned with the cylinder axis

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35. A -10D myopic eye has a magnification power of – 16.75x (70D/4)

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36. A +20 D condensing lens used in indirect ophthalmoscopy will form an image where? – 5cm behind the lens at its posterior focal plane, of course, assuming patient is emmetropic.

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37. Image characteristics of image in indirect ophthalmoscopy – Inverted, real

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38. TIR – 100% reflectance

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39. Refractive Index – velocity of light in air/velocity of light in medium

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40. Polarising sunglasses – vertically polarized to block horizontally polarized light

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41. Snellen acuity – each letter subtends an angle of – 5 min of arc

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42. Snellen acuity – each letter stroke subtends an angle of – 1 min of arc

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43. Contrast sensitivity – measured as a function of spatial frequency

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44. Contrast sensitivity and and clinical significance – amblyopia etc.

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45. Light transmission of 2 means the medium allows transmission of 

a. 10%

b. 1%

c. 0.1%

d. 50%

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46. Myopes with bifocal segments – best shape for the segment is the Flat top segment (reduces prismatic effect and thus reduces image displacement and subsequent heterophoria)

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47. Contact lenses – in general the best form of sclera lenses are 

a. Air ventilated rigid sclera lenses

b. Fluid ventilated rigid sclera lenses – Right answer

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48. In general, spherical soft contact lenses can be used in patients with astigmatism up to -1D

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49. Patient with -3.50D of CORNEAL astigmatism will prefer contacts over spectacles because

a. contacts will avoid the meridional aniseikonia from the significant corneal b.astigmatism by its tear lens masking the effect of the astigmatic cornea.

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50. Upper limit of LASIK correction is

a. 3D

b. 6D

c. 5D

d. 12D

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51. The minimal corneal bed thickness than can be left post excimer laser treatment is 

a. 50 microns

b. 500 microns

c. 250 microns

d. 100 microns

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52.  The acellular Bowman’s membrane is

a. Destroyed in LASIK

b. Intact in LASEK

c. Not affected in PRK

d. Does not regenerate

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53. The most common fitting for a spherical RGP lens is  - base curve matches anterior corneal curvature and its upper edge fits under the upper lid

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54. What are the peripheral curves of a contact lens – the posterior peripheral curvature of the lens outside the base curve of the lens

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55. In Gullstrand’s REDUCED schematic eye, the axial length is – 22.6mm

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56. In Gullstrand’s schematic eye, the eye has a power of - +58.64D

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57. Bandage Contact lenses are used mainly for – pain

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58. Fitting of rigid sclera contact lenses - features of a good fit

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59. Thin, high refractive glass has a RI of – 1.7

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60. Videokeratoscopes measure – Corneal topography

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61. In measuring the central corneal curvature,  the refractive index of the cornea is taken to be 1.3375

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62. Orthokeratology can correct errors up to

a. 12D

b. 9D

c. 6D

d. 3D

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63. The streak retinoscope is usually used with its sleeve in which setting? – Plano mirror setting

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64. With a large angle Kappa, the eye appears to be deviated

a. Superiorly

b. Inferiorly

c. Nasally

d. Temporally

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65. Conductive keratoplasty-?!!?

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66. Intrastromal corneal rings have the effect of – flattening the central portion of the cornea

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67. Pachymeters are used to measure 

a. Corneal thickness

b. AC depth

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68. The pupil that is seen is the ‘entrance pupil’ which is the image of the real pupil, magnified by the dioptric power of the cornea. How much larger is it compared to the real pupil – 13%

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69. What is the magnification of the retinal image in a previously emmetropic, aphakic eye with contact lenses? – 7-12%

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70. Most of the magnification in an operating microscope is provided by the

a. Objective lens

b. Astronomical telescope

c. Galilean telescope

d. Porro prism

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71. Zernicke polynomials are used to study? 

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72. Why is the viewing arm set at an angle to the illumination arm while performing specular microscopy?

 

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