NCLE questions with correct answers

What is the thickest layer of the cornea? - Answer stroma Which corneal layer controls the fluid content of the cornea? - Answer endothelium What is cornea edema? - Answer excess fluid in the stroma that can swell it and lead to loss of visual acuity What kind of contact lenses must be stabilized (not rotate) on the eye for good vision? - Answer toric contact lenses Concentric vs Aspheric Multifocal Lens Design - Answer aspheric multifocal lenses have a gradual change in power from distance to near where as the power change in concentric designs is not gradual eye dominance - Answer the preference of one eye over the other for visual acuity and monocular activity average central corneal curvature - Answer 7.8 mm of radius or 43.25D cornea's index of refraction - Answer 1.376 corneal apex - Answer Central and steepest part of the cornea, 3-5 mm in diameter. (also the only part of the cornea tested during keratometry reading) with-the-rule astigmatism - Answer the vertical corneal meridian has the steepest curvature against-the-rule astigmatism - Answer the horizontal meridian has the steepest curvature Oblique astigmatism - Answer regular astigmatism in which the principal meridians are other than 90 & 180 Irregular astigmatism - Answer The principal meridians are not 90 degrees apart HVID (horizontal visible iris diameter) - Answer measured corneal diameter. average= 11.7 mm