Dr Boothe

Reading glasses - Framed lenses that increase visual acuity for close distances. They become necessary when presbyopia develops after about age 40. See also Bifocals and Trifocals.

Dr William Boothe

Sclera - (SKLEH-ruh) The white outer layer of the eye, which is tough and protective. It joins smoothly with the cornea and continues in the back of the eye, connecting with the sheath that covers the optic nerve.

Scotopic Pupil Size - The size of the pupil in dim lighting conditions, as in moonlight.

Dr Boothe

: Phakic - An adjective describing an eye which has its natural crystalline lens intact.

Phakic Intraocular Lens (P-IOL) - A removable artificial lens which is placed in front of the natural lens, to increase its focusing ability.

Phoropter - A vision-testing instrument with many lenses, through which a person looks at the eye chart. As the lenses are switched, the person is asked which one gives the clearest images of the letters on the chart. On this basis, a prescription is determined for glasses or contact lenses. The eye chart is set first at 20 feet away, then at 16 inches away, to test both far and near vision.
Dr William Boothe