Optometry Glossary

Accommodative Convergence to Accommodation ratio — convergence (in prism dioptres) per dioptre of accommodation. Normal ~3:1 to 5:1.

Australian College of Optometry — the venue in Carlton, Melbourne where the COE clinical examination is held.

Assessment of Competence in Ocular Therapeutics — separate OCANZ assessment for therapeutic prescribing endorsement (Schedule 4 ocular medications).

Reading addition — extra plus power added to distance prescription for near, used in presbyopia, in dioptres.

Australian Health Practitioner Regulation Agency — administers national registration of health practitioners, including optometrists, in partnership with the Optometry Board of Australia.

Age-related Macular Degeneration — leading cause of vision loss in older Australians. Dry (atrophic) and wet (neovascular) forms.

Low-dose atropine used in myopia control in children; reduces myopia progression with minimal pupil dilation or accommodation effect.

Best Corrected Visual Acuity — visual acuity achieved with best refractive correction in place.

Branch Retinal Vein Occlusion — occlusion of a retinal vein branch, typically at an arteriovenous crossing.

Competency in Optometry Examination — the OCANZ assessment overseas-trained optometrists must pass to register in Australia or New Zealand. Comprises written + cultural safety + clinical components.

Continuing Professional Development — ongoing learning required for AHPRA registration renewal. Optometrists must meet the Board's annual CPD requirements.

Central Retinal Artery Occlusion — emergency producing sudden painless vision loss with cherry-red spot on fundus.

Central Retinal Vein Occlusion — blockage of the central retinal vein producing widespread retinal haemorrhages and oedema.

Clinically Significant Macular Oedema — older term defining macular oedema severity warranting treatment under ETDRS criteria.

Cycloplegic used for paediatric refraction. 0.5% (infants) or 1% (children/adults). Onset ~30 min, recovery ~24 hr.

Cylinder — astigmatic component of a refractive prescription, with axis specified in degrees (1–180).

Diabetic Macular Oedema — fluid accumulation at the macula in diabetes; significant cause of central vision loss.

Diabetic Retinopathy — microvascular complication of diabetes. Categorised as non-proliferative (NPDR) or proliferative (PDR).

Fundus Fluorescein Angiography — intravenous dye-based imaging of retinal circulation; used to assess leakage, ischaemia, neovascularisation.

Diagnostic dye used to assess corneal epithelial integrity, tear film, and fitting of rigid contact lenses. Stains epithelial defects.

Giant Cell Arteritis (temporal arteritis) — vasculitis of medium and large arteries in patients >50 years; causes arteritic AION. Suspect if jaw claudication, scalp tenderness, raised ESR/CRP.

Ganglion Cell Layer — retinal layer containing ganglion cell bodies; thinning is detected on OCT in glaucoma.

Examination of the iridocorneal angle using a gonioscopy lens; required to classify glaucoma as open- or closed-angle.

Internal Limiting Membrane — innermost layer of the retina, formed by Müller cell footplates.

Intraocular Pressure — measured in millimetres of mercury (mmHg). Normal range commonly 10–21 mmHg; elevated in ocular hypertension and glaucoma.

Progressive non-inflammatory thinning and conical protrusion of the cornea. Often presents in late adolescence with worsening astigmatism.

Transition zone between cornea and sclera; site of corneal epithelial stem cells.

Meibomian Gland Dysfunction — leading cause of evaporative dry eye disease.

Non-Arteritic Anterior Ischaemic Optic Neuropathy — sudden optic disc swelling and vision loss in the older patient. Distinguish from arteritic AION (giant cell arteritis).

Near Point of Convergence — closest point at which both eyes maintain bifoveal fixation. Receded NPC suggests convergence insufficiency.

Optometry Board of Australia — the National Board that sets standards and registers optometrists. Works through AHPRA.

Optometry Council of Australia and New Zealand — administers the Competency in Optometry Examination (COE) for overseas-trained optometrists.

Optical Coherence Tomography — non-invasive cross-sectional imaging of the retina, optic nerve, and anterior segment. Standard of care for glaucoma, AMD, DR.

OCT Angiography — non-invasive imaging of retinal and choroidal vasculature without dye.

Primary Angle-Closure Glaucoma — narrow or closed iridocorneal angle; can present as acute angle closure with red painful eye and vision loss.

Measurement of central corneal thickness (CCT). Influences IOP interpretation and is required prior to refractive surgery.

Pupillary Distance — distance between pupil centres in millimetres; required for spectacle dispensing.

Sympathomimetic mydriatic without cycloplegia. 2.5% commonly combined with tropicamide for dilated fundus exam.

Primary Open-Angle Glaucoma — most common form of glaucoma in Australia; chronic, progressive, usually asymptomatic until advanced.

Topical anaesthetics for tonometry, foreign body removal, gonioscopy.

Posterior Vitreous Detachment — separation of the vitreous from the retina. Symptoms: floaters, flashes. Examine for retinal tears.

Retinal Detachment — separation of the neurosensory retina from the RPE. Rhegmatogenous, tractional, or exudative. Urgent referral.

Retinal Nerve Fibre Layer — axons of ganglion cells running to the optic disc; thinning is a key glaucoma sign on OCT.

Retinal Pigment Epithelium — single layer of pigmented cells between the photoreceptors and Bruch's membrane. Critical for photoreceptor function and metabolism.

Sphere — spherical component of a refractive prescription, in dioptres. Negative for myopia, positive for hyperopia.

Tear Break-Up Time — time from a complete blink to the first dry spot on the cornea; <10 seconds suggests evaporative dry eye.

Map of corneal anterior surface curvature; key in keratoconus screening and contact lens fitting.

Short-acting mydriatic and cycloplegic; commonly used for fundus examination. 0.5% or 1%, peaks ~20–30 min, lasts ~4–6 hr.

Uncorrected Visual Acuity — visual acuity without any refractive correction.

Visual Field / Humphrey Visual Field — assessment of peripheral and central vision. SAP 24-2 and 10-2 are common protocols in glaucoma and macular disease.