NCLE Practice Test Questions With Verified Answers

base curve - Answer refers to the radius of curvature of the central posterior surface of the lens. It may be expressed in diopters of surface power (D) or in millimeters (mm) of radius or curvature. optical zone - Answer the chord diameter over which the base curve extends on the posterior surface of the contact lens, described in millimeters secondary or intermediate curves - Answer lies between the base curve and the peripheral curve on the posterior lens surface, usually 0.70mm to 1.50mm flatter than the base curve radius, this allows the lens to better align the flatter portion of the cornea adjacent to the optical zone peripheral curve - Answer the outermost curve on the posterior lens surface, its function is to clear the flatter periphery of the cornea and to prevent lens impingement in the limbal areas as the lens moves with blinking blend curve - Answer the treatment given to the sharp junctions created by the difference in the radii of curvature between the base curve, the secondary curve, and the peripheral curve, rarely required at the base curve/secondary curve junction. lens diameter - Answer refers to the overall width of the lens from one edge to the other, it is measured in millimeters. Normal ranges are from 7.00mm to 10.50mm in rigid lenses and from 12.50mm to 16.00mm in soft contacts center thickness - Answer the measurement in millimeters from the anterior to the posterior surface of the lens at its geometric center, this measurement varies significantly depending on the power of the lens anterior - Answer nearer the front, especially situated in the front of the body or nearer to the head posterior - Answer further back in position; of or nearer the rear or hind end, especially of the body or a part of it. lens power - Answer the difference between the radii of the anterior and posterior lens surface abrasion - Answer rubbing off of the superficial layer accommodation - Answer adjustment by the eye for seeing different distances, accomplished by changing the shape of the crystalline lens through action of the ciliary muscle acuity - Answer clearness; measured by the smallest object that can seen at a certain distance adnexa oculi - Answer accessory structures of the eye, such as lacrimal apparatus and the eye lids albinism - Answer hereditary loss of pigment in the eye, skin & hair; usually associated with lowered visual acuity, nystagmus & light sensitivity amblyopia - Answer loss of vision with any apparent disease of the eye ametropia - Answer a refractive error in which the eye, when in state of rest, does not focus the image of an object upon the retina; includes hyperopia,myopia and astigmatism aniridia - Answer congenital absence of the iris aniseikonia - Answer a condition in which the ocular image of an object as seen by one eye differs so much in size or shape from the seen by the other eye that the two images cannot be fused into a single impression aniscoria - Answer inequality of the pupils in diameter anomaly - Answer departure from the normal anopthalmia - Answer absence of a true eyeball anterior chamber - Answer space in front of the eye, bounded in front by the cornea and behind by the iris; filled with aqueous humor antibody - Answer a specific substance produced by the body in the presence of an antigen antigen - Answer any substance that acts against the action of histamine aphakia - Answer absence of the crystalline lens of the eye aqueous humor - Answer clear, watery fluid that fills the anterior and posterior chambers within the front part of the eye arcus senilus - Answer grayish white ring in the periphery of the cornea asthenopia - Answer eye fatigue caused by tiring of the internal and/or external muscles astigmatism - Answer a refractive error that prevents light rays from coming to a single focus on the retina because of different degrees of refraction in the various meridians of the eye against-the-rule astigmatism - Answer condition in which the steepest corneal meridian is in the horizontal plane. An example of keratometer readings for a patient exhibiting this condition would be: K's 45.00@180/42.00@90 irregular astigmatism - Answer astigmatism caused by an irregularly shaped cornea lenticular astigmatism - Answer astigmatism found in the crystalline lens oblique astigmatism - Answer regular astigmatism in which the principal meridians are other than 90 & 180 residual astigmatism - Answer astigmatism remaining after the corneal astigmatism has been neutralized with-the-rule astigmatism - Answer condition in which the steepest corneal meridian is in the vertical plane, an example of keratometer reading for a patient exhibiting this condition would be: K's: 42.00@180/45.00@90 atrophy - Answer wasting or decrease of tissue due to faulty nutrition or loss of verve supply back vertex power (BVP) - Answer when neutralizing a lens, the concave or the posterior side of the lens in placed against the aperture of the lensometer bedewing (Cornea) - Answer an edematous condition of the epithelium of the cornea characterized by irregular reflecting from a multitude of droplets when the cornea is viewed with the slit lamp