Test 3

1. Spasm of accommodation: a. can masquerade myopia  b. results in presbyopia  c. occurs more frequently in hypermetropia  d. causes convergence insufficiency  e. can be alleviated by miotics Answer1.    a.F    b.F    c.T    d.F    e.F Accommodation spasm: can masquerade hypermetropia by the moving the far point forward does not cause presbyopia which is caused by accommodation insufficiency more common in hypermetropia due to the attempted accommodative effort to bring the far point to he front  accommodation is closely linked to convergence. In accommodation spasm, there is esotropia which is variable can be alleviated by mydriatic 2. The following are true about schematic eye: a. it contains six cardinal pints  b. the cornea has a higher refractive power than the lens  c. the cornea has a higher refractive index than the lens  d. the anterior focal point is longer than the posterior point  e. the posterior lens surface has a larger radius of curvature than the      anterior lens surface Answer2.    a.T    b.T    c.F    d.F    e.F Schematic eye: is a modified eye which is used to represent the optical system of the eye it has a primary and secondary focal points, two principal points and two nodal points totalling six cardinal points the cornea accounts for 2/3 of the total eye power the cornea has a higher refractive power than the lens but a lower refractive index than the lens the anterior focal points is about 17.00 mm and that of the posterior focal point which is 22.60 mm the posterior lens surface is more curved than the anterior lens surface and therefore smaller radius of curvature 3. Image distortion from a cylindrical lens can be minimized by: a. decreasing the vertex distance  b. by reducing the cylinder power  c. using a toric contact lens  d. using plus cylinder lens  e. rotating the axis towards 90 or 180 degrees Answer3.    at    b.T    c.T    d.F    e.T Image distortion from cylindrical lens can be reduced by: reducing the vertex distance using minus cylinder spectacle lens using toric contact lens reducing the power of the cylinder rotating the axis towards 90 or 180 degrees 4. During streak retinoscopy, the following are true about the point of        neutrality: a. the reflex moves rapidly  b. the reflex becomes dimmer  c. moving towards the patient produces against movement in all meridians  d. the retinal and the peephole of the retinoscope forms the conjugate      points  e. the retinoscopic refraction is complete Answer4.    at    b.F    c.F    d.T    e.F At the point of neutrality: the reflex moves rapidly the reflex becomes brighter moving towards the patient produces with movement in all meridians the retina and the peephole of the retinoscope are conjugate in all meridians the working distance needs to be taken into account and therefore the refraction is not complete 5. Compared with soft contact lens, rigid gas permeable contact lens: a. is suitable for intermittent wear  b. gives a better vision  c. has a greater diameter  d. is more resistant to wear and tear  e. is not suitable for keratoconus    Answer5.    a.F    b.T    c.F    d.T    e.F Hard contact lens: requires sometimes to get use to and is not suitable for intermittent use gives a better vision has a smaller diameter

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