Flashcards on Optics - TimRoot.com

Here are flashcards about basic optics questions. Click on the cards for more information or if you’d like to leave a comment.

Will a child with cataract implants need glasses?

Yes. Even if the implant prescription is perfect for distance vision, the child will need bifocals for reading close up.

What is “with the rule” astigmatism?

This is when the axis of the positive cylinder in a pair of glasses is oriented at 90 degrees.

Are babies usually born myopic or hyperopic?

Babies have small eyes and are usually born hyperopic (far-sighted). Fortunately, they can accommodate their lens and still see near objects.

How might hyperglycemia affect a patient’s prescription?

High sugar leads to accumulation of sorbitol in the lens, swelling the lens and creating more myopia (nearsightedness).

What is presbyopia?

This is stiffness to the lens that occurs with age that makes it hard to read without glasses.

What is accommodation?

Accommodation is when the lens becomes “rounder” in order to focus nearby objects onto the retina.

What’s the difference between the axis and power of a cylinder?

A cylinder power (the refracting power of a lens) is 90 degrees from the axis of the cylinder.

What’s the difference between plus and minus cylinder?

These are ways to describe astigmatism in glasses. Ophthalmologists work in “plus” cylinder while optometrists like “minus” cylinder.

What is hyperopia?

A hyperopic (farsighted) eye is a small eye, such that images focus behind the eye. It is treated with plus power lenses.

What is myopia?

This is nearsightedness (also called short-sighted in other countries) which means that you can see near, but have problems with distant objects.