Optometry Lingo

Nigeria Optometry Students' Association — the national body representing optometry students across all universities in Nigeria.

A university-level branch of NOSA. Each recognised optometry school has its own chapter.

Short for Executive Committee — the elected officers who manage either the national association or a chapter.

The supreme deliberative body of NOSA, comprising delegates from all chapters. Meets annually to set direction and make key decisions.

Activities and initiatives designed to support student wellbeing, ranging from financial aid to mental health awareness.

A distinguished senior optometrist or stakeholder who lends guidance and mentorship to a chapter or the national body.

A measure of how clearly the eye resolves fine detail, typically expressed as a fraction (e.g. 6/6 or 20/20).

The clinical procedure for determining the lens prescription needed to correct a patient's refractive error.

The ideal state where the eye is in perfect focus at distance with no accommodative effort.

Nearsightedness — objects up close are clear but distant objects appear blurred. Corrected with minus (concave) lenses.

Farsightedness — the eye is too short or the cornea too flat, making near objects harder to focus on. Corrected with plus (convex) lenses.

An irregular curvature of the cornea or lens causing distorted or blurred vision at all distances. Corrected with cylindrical lenses.

The age-related loss of near focusing ability, typically noticed after age 40, caused by reduced lens flexibility.

A significant difference in refractive error between the two eyes, which can lead to amblyopia if uncorrected in childhood.

The eye's ability to change focus from distant to near objects by altering the curvature of the crystalline lens.

Intraocular Pressure — the fluid pressure inside the eye. Elevated IOP is a major risk factor for glaucoma.

The clinical measurement of IOP, performed with instruments such as a non-contact tonometer or Goldmann applanation tonometer.

Commonly called "lazy eye" — reduced vision in one eye due to abnormal visual development in early childhood, often without obvious structural cause.

Misalignment of the eyes (e.g. esotropia — inward turn; exotropia — outward turn). Can cause diplopia (double vision) or amblyopia.

A group of eye diseases characterised by damage to the optic nerve, often associated with elevated IOP, leading to progressive vision loss.

Clouding of the crystalline lens, reducing the amount of light reaching the retina. The leading cause of reversible blindness worldwide.

Deterioration of the macula (the central retina), causing loss of central vision. Age-related macular degeneration (AMD) is the most common form.

Damage to retinal blood vessels caused by poorly controlled diabetes, potentially leading to vision loss or blindness.

The clear, dome-shaped front surface of the eye responsible for the majority of the eye's refractive power.

The light-sensitive layer lining the back of the eye that converts light signals into electrical impulses sent to the brain.

The small central region of the retina responsible for sharp, detailed central vision and colour perception.

The nerve that transmits visual information from the retina to the brain. Damage to it (e.g. in glaucoma) causes irreversible vision loss.

The coloured part of the eye that controls the size of the pupil and therefore the amount of light entering the eye.

The transparent, flexible structure behind the iris that fine-tunes focus by changing shape (accommodation).

The clear, gel-like substance filling the space between the lens and the retina, giving the eye its round shape.

The interior posterior surface of the eye, including the retina, optic disc, macula, and posterior pole — examined with an ophthalmoscope.

A binocular microscope used to examine the anterior and posterior segments of the eye under high magnification and focused illumination.

An instrument used to examine the interior of the eye (fundus). Direct and indirect types exist.

A handheld instrument that projects light into the eye to objectively determine refractive error — the basis of retinoscopy.

An automated instrument that measures the eye's refractive error quickly as a starting point before subjective refraction.

A procedure to map the full extent of the visual field, used to detect and monitor conditions like glaucoma and neurological disorders.

Measurement of the curvature of the corneal surface, essential for contact lens fitting and pre-surgical assessment.

Optical Coherence Tomography — a non-invasive imaging technique that produces high-resolution cross-sectional images of retinal layers.

An ultrasound imaging technique used to visualise intraocular structures when optical methods are not possible (e.g. dense cataract).

The component of a spectacle prescription that corrects myopia (minus values) or hyperopia (plus values).

The component that corrects astigmatism, specifying the lens power along one meridian.

The orientation (in degrees, 0–180) of the cylindrical component in a spectacle prescription.

The additional plus power added to the distance prescription for near correction — used in bifocals and progressive lenses.

A lens element that displaces the image to compensate for eye muscle imbalance (strabismus) or prismatic demand.

Pupillary Distance — the distance between the centres of the two pupils, critical for centring lenses correctly in a frame.

Near/Distance Visual Outcome — recorded after a refraction to document how well the patient sees at near or far with the new prescription.