Definitions of common terms

I'm reposting these definitions from the emmetropia thread hoping that it will help communications. I will edit this first post if anyone finds an error or wants me to add any items or clarifications.

all definitions assume accommodation is at rest, except for the first one and the last 5.

Accommodation (aka focusing): temporarily changing the refractive state of an eye resulting from a change in the crystalline lens shape due to an autonomic stimulus of the ciliary muscle.

Emmetropia=0.00 refractive error

Myopia (aka near-sightedness, short-sightedness)=negative refractive error, using spherical equivalent when astigmatism is present

Hyperopia (aka far-sightedness, long-sightedness, hypermetropia)=positive refractive error, using spherical equivalent " ".

Ametropia=any refractive state other than emmetropia.

Regular Astigmatism=any toric or cylindrical refractive error that can be completely defined by adding a cylinder and axis to a spherical component

Irregular astigmatism=any toric or cylindrical refractive error than cannot be completely defined by sphere cylinder and axis.

Anisometropia=a significant difference in refraction between the two eyes

Antimetropia=myopia in one eye and hyperopia in the other

Presbyopia=age related decrease in accommodation function

Heterotropia (aka strabismus, squint)=a manifest misalignment of the visual axes of the two eyes. (Esotropia is inward deviation, aka crossed eyes, exotropia is outward deviation aka wall eyed, hypertropia/hypotropia are vertical deviations)

Heterophoria=a latent misalignment of the visual axes of the two eyes (esophoria, exophoria, hyperphoria, and hypophorias are similar latent tendencies as above)

Orthophoria=zero misalignment of the visual axes of the two eyes.

Amblyopia (aka lazy eye, amblyopia ex anopsia)=an otherwise healthy eye that is not correctible to normal acuity due to strabismus, or to moderate to large amounts of uncorrected ametropias in childhood.

Definitions of common terms