Table 2.

Glossary

Term	Definition
Accommodation	Contraction of the ciliary muscle resulting in a change of lens shape.53
Asthenopia	Subjective symptoms of ocular fatigue or eye strain.53
Astigmatism	Type of refractive error due to imperfection in the curvature of the eye that causes blurred distance and near vision.54
Cycloplegic refraction	A technique used to calculate the complete refractive error by temporarily paralysing the ciliary muscle of the eye that aids in focusing.53
Diplopia	Disorder of vision in which two images of a single object are seen.53
Dry eye	Alteration of ocular surface homeostasis characterised by an alteration of the tear film.
Emmetropia	Refractive state of an eye in which parallel rays of light entering the eye are focused on the retina, creating an image that is perceived as crisp and in focus.55
Esotropia	Eye misalignment in which one eye is deviated inward, or nasally.54
Hyperopia	Ocular condition in which the refracting power of the eye causes light rays entering the eye to have a focal point that is posterior to the retina while accommodation is maintained in a state of relaxation.54
Myopia	Ocular condition in which the refracting power of the eye causes light rays entering the eye to have a focal point that is anterior to the retina while accommodation is maintained in a state of relaxation.54
Orthokeratology	Use of specially designed and fitted contact lenses to temporarily reshape the cornea to improve vision.56
Refractive errors	Type of vision problem that makes it hard to see clearly and happens when the shape of your eye keeps light from focusing correctly on your retina.55
Spherical equivalent refraction	Estimate of the eyes’ refractive error, calculated independently for each eye. It is calculated by merging the spherical (near-sightedness or far-sightedness) and cylindrical (astigmatism) refractive error components.54
Vergence	The turning motion of the eyeballs towards (convergence) or away (divergence) from each other.53