Resources
Eye care glossary
Every term here appears somewhere on this site or in a real appointment. Definitions are written to be understood rather than to be technically exhaustive.
- Accommodation
- Accommodation is the process by which the lens inside the eye changes shape to bring near objects into focus. It is driven by the ciliary muscle and it weakens gradually from childhood, becoming noticeable in the mid forties as presbyopia.
- Amblyopia
- Amblyopia, commonly called lazy eye, occurs when one eye is not used properly during early visual development, so the brain pathway carrying its signal fails to develop. Treatment is far more effective before around age seven. The eye itself is usually structurally normal.See also: Strabismus
- Aqueous deficient dry eye
- The lacrimal gland does not produce enough tear volume. Less common than evaporative dry eye, and associated with age, autoimmune conditions and a range of medications.See also: Evaporative dry eye
- Astigmatism
- The eye's surface is curved more steeply in one meridian than another, so light focuses at two points rather than one. Regular astigmatism is corrected with toric lenses. Irregular astigmatism, as in keratoconus, needs specialty lenses.See also: Toric lens, Keratoconus
- Axial length
- The measurement that tracks true myopia progression. A longer eye means a stretched, thinner retina and permanently raised lifetime risk of retinal detachment, myopic maculopathy and glaucoma. Myopia control aims to reduce the final axial length reached.See also: Myopia
- Blepharitis
- Inflammation at the lid margin, often involving bacteria and debris at the lash line. Frequently coexists with meibomian gland dysfunction and is treated with lid hygiene.See also: Meibomian gland dysfunction
- Cataract
- The lens inside the eye gradually loses transparency, scattering light rather than focusing it. Causes blurred vision, glare and faded colours. Treated surgically, with timing driven by how much it interferes with daily life.
- Convergence insufficiency
- The eyes struggle to converge adequately for reading, or to hold convergence once achieved. Produces blur, doubling and headaches after several minutes of close work. Invisible on a distance vision chart and treatable.
- Cornea
- The transparent front surface of the eye. It performs around two thirds of the eye's focusing, which is why its shape matters so much and why an irregular cornea cannot be corrected with glasses.
- Corneal cross linking
- Riboflavin drops and controlled ultraviolet light strengthen the bonds between corneal collagen fibres, stiffening the cornea. It preserves the cornea as it currently is rather than recovering earlier shape, which is why timing matters.See also: Keratoconus
- Corneal topography
- Projected rings are measured as they reflect off the cornea, building a map from over 20,000 surface points. Detects keratoconus early and is the design input for every specialty and Ortho-K lens.See also: Keratoconus, Orthokeratology
- Diabetic retinopathy
- Diabetes damages the small blood vessels of the retina, producing microaneurysms, haemorrhages and swelling. It develops silently and is a leading cause of preventable vision loss, which is why annual screening is the standard of care.
- Drusen
- Small deposits that accumulate under the retina at the macula. Their presence, number and size are markers for age related macular degeneration risk and are tracked with retinal imaging over time.See also: Macular degeneration
- Evaporative dry eye
- Enough tears are produced but the oily layer that prevents evaporation is not working, usually because the meibomian glands are blocked. Far more common than aqueous deficiency, and the reason artificial tears often fail.See also: Meibomian gland dysfunction
- Fluorescein
- A harmless orange dye that glows under cobalt blue light, making the tear layer and any corneal surface damage directly visible. Used for contact lens fit assessment and for detecting abrasions and ulcers.
- Glaucoma
- Damage to the optic nerve, usually but not always associated with raised eye pressure. Peripheral vision is lost gradually and silently, and lost vision cannot be recovered. Normal eye pressure does not rule it out.See also: Intraocular pressure, Visual field
- High index lens
- Materials with a higher refractive index achieve the same correction with less curvature and therefore less thickness. The benefit is most noticeable above about three dioptres.
- Hydrops
- A break in the inner corneal layer allows fluid into the cornea, causing sudden swelling, clouding and light sensitivity. Uncommon and needs prompt assessment.See also: Keratoconus
- Intraocular pressure
- A major risk factor for glaucoma and the target of most glaucoma treatment. A normal reading does not exclude glaucoma, because normal tension glaucoma occurs within the normal pressure range.See also: Glaucoma
- Invisalens
- The practice's branding for its overnight vision correction service, covering candidacy assessment, custom lens design, fitting, training and follow up. The underlying technique is orthokeratology.See also: Orthokeratology
- Keratoconus
- The cornea thins and bulges forward, producing irregular astigmatism that glasses cannot correct. Diagnosed with corneal topography and managed with specialty contact lenses and, where appropriate, cross linking.See also: Corneal topography, Scleral lens, Corneal cross linking
- Macular degeneration
- Affects the macula, the small central retinal area responsible for detailed vision. The dry form progresses slowly. The wet form involves abnormal blood vessel growth and can cause rapid central vision loss requiring urgent treatment.See also: Drusen
- Meibomian gland dysfunction
- Glands in the eyelid margins secrete the oil that stops tears evaporating. When they block or the oil thickens, the tear film loses its protective layer. Treatment requires sustained heat and lid hygiene over six to eight weeks.See also: Evaporative dry eye
- Myopia
- Light focuses in front of the retina rather than on it, usually because the eyeball is too long. In children it progresses as the eye elongates, which is what myopia control aims to slow.See also: Axial length
- OCT
- Uses light waves to build a cross section of ocular tissue at microscopic resolution. Measures retinal nerve fibre layer thickness for glaucoma, macular structure, corneal layers and scleral lens vault.
- Optomap
- Scanning laser imaging that captures over 80 percent of the retina in a single image without dilating drops. Particularly valuable for the peripheral retina where tears and early diabetic changes appear.
- Orthokeratology
- A custom rigid lens worn during sleep gently reshapes the corneal surface, giving clear daytime vision without glasses. Developed in 1962. Fully reversible, and it also slows myopia progression in children.See also: Invisalens, Corneal topography
- Pachymetry
- Measures corneal thickness at multiple points. Important for keratoconus severity, cross linking candidacy, refractive surgery safety and interpreting eye pressure readings.
- Presbyopia
- The lens inside the eye loses flexibility with age, making near focus progressively harder from the mid forties. It happens to everyone regardless of distance vision and is corrected with reading glasses, progressives or multifocal lenses.See also: Accommodation
- Pterygium
- A wedge shaped growth of conjunctival tissue onto the cornea, more common in sunny, dusty and windy climates. Can affect vision if it grows across the pupil and can destabilise the tear film.
- Refraction
- The sequence of lens comparisons that refines an objective starting measurement into the prescription your visual system actually prefers. Objective refraction, used for infants, requires no responses at all.
- Retinal detachment
- Fluid passes through a retinal tear and lifts the retina away from the wall of the eye. A surgical emergency. Typically preceded by sudden floaters, flashes and a shadow moving across the vision.See also: Retinal tear
- Retinal tear
- A hole in the retina, most often in the far periphery, caused by the vitreous gel pulling as it separates. Treatable with laser if caught before detachment occurs.See also: Retinal detachment, Vitreous
- Scleral lens
- Arches completely over the cornea and lands on the white of the eye, with a saline reservoir underneath. Restores vision for irregular corneas and provides continuous surface relief in severe dry eye.See also: Keratoconus
- Slit lamp
- A binocular microscope with a controllable slit of light, used to examine the cornea, lens, lids, tear film and, with additional lenses, the retina.
- Strabismus
- One eye turns in, out, up or down while the other fixates. Can be constant or intermittent. Untreated it commonly causes amblyopia because the brain suppresses one image.See also: Amblyopia
- Tear film break up time
- Measures tear film stability. A short break up time indicates evaporative dry eye and is one of the key measurements distinguishing it from aqueous deficiency.See also: Evaporative dry eye
- Toric lens
- Weighted or shaped to stay rotationally stable on the eye, because the correction only works when correctly aligned. Available in soft, rigid and scleral designs.See also: Astigmatism
- Visual field
- Mapped by presenting targets across the field of view and recording which are detected. The standard test for glaucoma damage and for neurological field defects, because it measures function rather than structure.See also: Glaucoma
- Vitreous
- Liquefies with age, causing floaters as collagen fibres clump. Its eventual separation from the retina, posterior vitreous detachment, is normal but can tear the retina where adhesion is strong.See also: Retinal tear
- Wavefront analysis
- Measures higher order aberrations that a standard prescription cannot describe. Explains why vision feels the way it does in irregular corneas better than an acuity score does.
- WOW Warranty
- The practice's guarantee on eyewear it sells, covering unlimited replacement, alongside a 120 day redo guarantee and free cleaning, repairs and adjustments for as long as the frame is worn.
A
B
C
D
E
F
G
H
I
K
M
O
P
R
S
T
V
W
Something on your notes you do not recognise?
Bring it to your appointment and ask. Two patients an hour means there is time to explain it properly. Call (480) 706-3937.