King Saud University College of Applied Medical Sciences Optometry Department OPTO-273: First Mid-Term Exam April   9th, 2007

                         Time Allowed:                             1 Hour

                         Student’s Name:       ___________________________

                         Student’s Number:   ___________________________

                          Course Instructor:              Dr. Idriss M. Bedja

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Question 1      In a good illumination, the human optical system can reach a maximum resolution

(1.25 Mark)     of :     40 lines per centimeter at a viewing distance of 40 cm

 

Question 2      To what have the retinal impressions of the visual scene been converted to

(2.5 Mark)       reach the visual cortex?             Visual impulses     TO      chemical impulses

                             TO      Electrical impulses before reaching the visual cortex

Question 3      There are specific neural channels for the detection of: (give two important aspects

(1.75 Mark)     of the visual scene)

1-                  Horizontal and vertical lines            

2-                  Different spatial frequencies

Question 4      When can we suspect neurological disorder in the pupil? Mention some reflexes

(1.5Mark)        failures:  Failure in direct, near and consensual reflexes

 

Question 5      Make a draw to show the cardinal points of the unaccommodated

(1.75 Mark)     schematic eye:     SEE THE CORRESPONDING LECTURE

 

Question 6      What will happen if the elasticity of the crystalline lens becomes less

(1 Mark)          elastic?  The accommodation decreases

 

Question 7      Why do the vitreous and aqueous humors have almost the same index of

(1 Mark)          refraction? Because both are composed of almost the same components

 

Question 8      The real images are formed in the cortex by the eye’s optical system.

(0.75 Mark)                 True:……                    False:…X..

 

Question 9      How entrance and exit pupils have been formed (brief answer)? …….

(2 Marks)       The entrance pupil is formed when the real pupil acts as an object

                       for the cornea and exit pupil when real pupil acts as an object for 

                      the lens.

 

Question 10    Crystalline lens' principal axis does not coincide with that of the cornea. 

(2 Marks)         Why? Because the crystalline lens is titled with respect to cornea

                              axis.

 Question 11    Make a draw of a schematic eye showing the optical axis and the visual

(1.75 Mark)     axis and define all nomenclatures inside.

                                     SEE THE CORRESPONDING LECTURE

 Question 12    Optical axis coincides with:

(1 Mark)

·         The lens' axis

·         The cornea's axis

·         The visual axis

·         None of them   X

 

Question 13    The optical axis in object space is above the visual axis, the angle between

(0.75 Mark)     being 2°.          True: …….      False: …X…..

 

Question 14    Nose, eyebrow and cheekbone limit the visual  in the temporal side.

(0.75 Mark)                             True: …….     False: …X…..

Question 15    Make a draw to show the relative sizes and positions of the macula and

(2.25 Marks)    optic disc of the left eye, indicating also the corresponding blind area.

 SEE THE CORRESPONDING LECTURE, BUT HERE YOU HAVE TO REVERSE THE PICTURES, MACULA AT RIGHT SIDE AND OPTIC NERVE AT LEFT SIDE (THIS IS LFT EYE)

 

Question 16    How first and second Purkinje images are formed? (Brief answer)

(3 Marks)          The first Purkinje image is formed by the reflection of light upon the anterior surface of cornea and the second image by the reflection of light uponthe posterior surface of cornea.

                                  Good Luck