This document defines common abbreviations used in ophthalmology, including XT for exotropia, ST for esotropia, astim for astigmatism, EM for emmetropia, MY for myopia, RK for radial keratotomy, LASIK for laser-assisted insitu keratomileusis, OD for right eye, and OS for left eye. It also provides the definitions for these medical terms and conditions, such as exotropia referring to an outward turning of the eye and myopia meaning nearsightedness.

1. CHAPTER 13
Samantha Loebbaka

2. XT
• XT is the abbreviation for Exotropia.
• Outward turning of the eye.
• Also called wall-eyed.
• Muscle weakness of the eye.

3. ST
• ST is the abbreviation for esotropia.
• Inward turning of eye.
• Also called cross-eyed.
• Muscle weakness of eye.

4. ASTIGM
• Astim is the abbreviation for astigmatism.
• Condition in which light rays are focused unevenly on the retina, causing a
distorted image, due to an abnormal curvature of the cornea.

5. EM
• EM is the abbreviation for emmetropia.
• State of normal vision.

6. MY
• My is the abbreviation for myopia.
• Nearsightedness
• Corrected with diverging or bicocnave lenses.
• Often squint or partially shut their eyes.

7. RK
• RK is the abbreviation for radial keratotomy.
• Spokelike incisions around the cornea that result in becoming flatter.
• A surgical treatment for myopia.

8. LASIK
• LASIK is the abbreviation for laser-assisted insitu keratomileusis.
• Laser surgery to remove corneal tissue.

9. OD
• OD is the abbreviation for right eye.

10. OS
• OS is the abbreviation for left eye.

11. PERRLA
• PERRLA is the abbreviation for pupils equal, round, react to light and
accommodation.