FREE Opticianry Competency Questions and Answers
What refractive state causes light to focus straight on the retina?
The medical word for spontaneously occurring vision is emmetropia. Because the light entering the eye focuses directly on the retina, an emmetropic eye does not require vision correction. When light concentrates behind the retina, a condition known as hyperopia, or farsightedness, results, whereas myopia, or nearsightedness, happens when light focuses in front of the retina.
The index of refraction of the cornea is:
At the cornea-air surface of the eye, refraction occurs most frequently. The rays leave the cornea and enter the aqueous humor, which has a refractive index of roughly 1.336, making the cornea's refractive index about 1.37. The aqueous humor fills the region in front of the eyeball between the lens and the cornea.
Which of the following attributes of a titanium frame is a benefit?
Titanium instantly produces a robust protective oxide film when it is exposed to oxygen and moisture, making it completely corrosion resistant. An additional benefit of a titanium frame is that folks with sensitive skin or nickel allergies won't experience an allergic reaction to the metal due to its hypoallergenic properties. The metal's stiffness enables the frame to maintain its shape, making it harder rather than simpler to adapt for the dispenser. Memory metal frames, also known as nickel titanium alloys, are not constructed of 100% titanium and will, after being bent, revert to their former shape.
Which phrase best describes the outward inclination of a framed lens's bottom?
Retroscopic tilt refers to the modification made to a frame that pushes the front edge of the frame away from the face. This modification is made to stop a frame from resting against someone's cheek. Every 2 degrees of pantoscopical tilt will increase the portion of the bridge surface that rests on the nose and raise the ocular center of the lens by 1 millimeter. Retroscopic tilt, on the other hand, will bring the ocular center down. To improve vision, each frame should have a pantoscopic tilt that balances the vertex in the 90-degree meridian. Periscopic refers to having clear eyesight all around rather than only in a clear, direct path, as in periscopic vision. An adverb that describes something is retractive.
The cornea of an astigmatized patient is ________.
The middle layer of the cornea, which is the clear layer covering the outside of the eye, is the thickest and is formed of water and the protein collagen. The cornea's normal round shape is maintained by the collagen, which also gives it strength and flexibility. Astigmatism develops when the cornea, lens, or front surface of the eye all have uneven or malformed curves, resulting in blurry vision at all distances. A foggy cornea is typically an indication of scarring, an infection, an abrasion, or eye edema.
What is Aphakia?
Aphakia is the medical term for the crystalline lens' absence. This disorder may be inherited or brought on by an injury. During cataract surgery, an ophthalmologist will often remove the crystalline lens and replace it with an artificial lens to correct vision. The reduced ability of the eyes to focus while changing distances is referred to as accommodation. The crystalline lens may be removed during cataract surgery if a cataract or refractive defect is present, although this is not a requirement for the diagnosis of aphakia.
How is typically measured multifocal height?
The distance between the lower lens edge and the pupil's center is known as the multifocal height. For appropriate multifocal installation, it is always crucial to fit the frame to the wearer before taking a measurement. The multifocal will be positioned too high if the measurement is taken from the lower border of the frame, which will add extra millimeters to the measurement. The multifocal will most likely be set too low if you measure to the lower border of the frame or lens.