Week 6

Question 1

Presbyopia

Answer 1

Normal distance vision, but lens loses elasticity w age and is unable to assume spherical shape. Fix is to use half convex lenses (reading) which allows refracted light to strike surface of cornea at smaller angle.

Question 2

Hyperopia

Answer 2

Refractive power of lens system is too weak or eyeball too short. When viewing distance, object is focused at point beyond retina.

Question 3

Myopia

Answer 3

Refractive power of lens system is too strong or eyeball too long. Near-sighted, sees distant objects as blurry. Uses concave lenses that diverge the light rays entering eye. May need bifocals w age.

Question 4

Astigmatism

Answer 4

Cornea surface isn’t spherical-more oblong. Corrected w cylindrical lens having a curvature that corrects for corneal astigmatism.

Question 5

Monocular visual field

Answer 5

Area in space visible to one eye. Potential visual field is described as hemisphere. (Nasal and temporal hemisphere)

Contains blindspot in temporal hemifield.

Question 6

Binocular field

Answer 6

Area of overlap between both eyes.

Question 7

Visual acuity

Answer 7

Ability to detect and recognize small objects visually depends on refractory (focusing) power of eye’s lens system and cytoarchitecture of retina. (Eye chart used to measure visual acuity)