Ophthalmology Glossary

Sight-threatening infection in contact-lens wearers; pain disproportionate to signs with ring infiltrate and radial keratoneuritis.

The eye’s ability to change focal power by altering lens shape via ciliary muscle contraction, allowing clear vision at varying distances.

Sharpness of central vision, typically measured with Snellen or logMAR charts at 6 m (20 ft).

A dilated, slow-reacting pupil with sectoral palsy due to post-ganglionic parasympathetic denervation; classically constricts to dilute pilocarpine 0.125%.

Asymmetric pupillary response on swinging-flashlight test indicating optic nerve dysfunction or extensive retinal disease.

Anterior ischaemic optic neuropathy; arteritic form (GCA) requires urgent steroids while non-arteritic affects vasculopaths with crowded discs.

IgE-mediated conjunctival inflammation with itching, chemosis, and papillae; managed by avoidance and mast-cell stabilisers / antihistamines.

Transient monocular vision loss lasting seconds to minutes, usually embolic from carotid disease; warrants urgent vascular workup.

Reduction in best-corrected visual acuity from abnormal visual development during the sensitive period; causes include strabismus, anisometropia, and deprivation.

A grid used to test the central 20° of vision for scotomas and metamorphopsia, especially in macular disease.

Process of new vessel formation driven by VEGF; therapeutically blocked by aflibercept, ranibizumab, bevacizumab in DR, AMD, and RVO.

Apposition of the peripheral iris to the trabecular meshwork blocking aqueous outflow, raising IOP.

Congenital partial or complete absence of the iris, usually bilateral; associated with PAX6 mutations and Wilms tumour risk in sporadic cases.

Unequal pupil size; differentiated by greater anisocoria in light (efferent defect) vs dark (sympathetic / Horner).

Difference in refractive error between the two eyes; ≥1.5 D is generally amblyogenic in children.

Fluid-filled space between cornea and iris containing aqueous humour; depth is key in angle-closure assessment.

Absence of the crystalline lens, surgical or congenital; causes high hyperopia and loss of accommodation.

Clear fluid secreted by the ciliary epithelium; maintains IOP and nourishes avascular ocular structures.

Posterior diversion of aqueous into vitreous causing shallow anterior chamber and high IOP after intraocular surgery in narrow-angle eyes.

Peripheral corneal lipid ring deposition with age; under 50 raises suspicion of dyslipidaemia.

Small irregular pupils with light-near dissociation, classically associated with neurosyphilis.

Lens with a non-spherical surface reducing spherical aberration and improving contrast sensitivity, especially in mesopic conditions.

Refractive error from non-spherical corneal/lenticular curvature producing two focal lines instead of a point image.

Objective instrument that estimates refractive error using infrared light and feedback optics.

Earliest stage of non-proliferative DR with microaneurysms, dot/blot haemorrhages, and hard exudates.

Systemic vasculitis with recurrent oral/genital ulcers and bilateral non-granulomatous panuveitis with shifting hypopyon.

Reflex upward and outward deviation of the globe on attempted lid closure; protects against exposure in facial palsy.

Autosomal-dominant vitelliform macular dystrophy (BEST1/VMD2) with a reduced Arden ratio on EOG.

Chronic inflammation of the lid margins (anterior/staphylococcal or posterior/meibomian gland dysfunction).

Surgical removal of redundant eyelid skin and fat, performed for dermatochalasis or aesthetic reasons.

Acellular subepithelial layer of the cornea; does not regenerate after injury, leading to scarring.

Mechanical restriction of the superior oblique tendon limiting elevation in adduction with positive forced duction.

Five-layered basement complex between RPE and choriocapillaris; thickens with age and is central to AMD.

Enlargement of the globe in congenital glaucoma due to scleral stretching before age 3.

Small tubular structure draining tears from the puncta into the lacrimal sac.

Any opacification of the crystalline lens reducing transparency and visual acuity.

Acute painless monocular vision loss with pale ischaemic retina and cherry-red spot; an ocular stroke requiring stroke workup.

Sudden monocular vision loss with diffuse retinal haemorrhages ("blood and thunder") and dilated tortuous veins.

Localised serous detachment of the neurosensory retina at the macula, typically in young men and steroid users.

Chronic lipogranulomatous inflammation of a meibomian gland presenting as a painless lid nodule.

Oedema of the bulbar conjunctiva; seen in allergies, infections, orbital congestion, and severe trauma.

Crossing of nasal optic-nerve fibres; lesions classically cause bitemporal hemianopia.

Highly vascular pigmented layer between sclera and retina; supplies the outer retinal layers.

Commonest primary intraocular malignancy in adults; appears as a pigmented dome- or mushroom-shaped subretinal mass.

New vessels growing from choroid through Bruch membrane; key lesion of wet AMD, treated with anti-VEGF.

Ring of muscle and processes producing aqueous humour and providing accommodation via the lens zonules.

Unilateral idiopathic retinal telangiectasias causing exudative retinal detachment, classically in young boys.

Inherited disorders with progressive cone-photoreceptor degeneration causing photophobia, decreased acuity, and dyschromatopsia.

Translucent mucous membrane covering the sclera (bulbar) and inner lid (palpebral).

Salmon-pink subconjunctival mass, usually MALT-type B-cell lymphoma; biopsy and systemic workup required.

Avascular transparent anterior coat of the eye providing ~70% of refractive power.

UV-A and riboflavin-induced collagen cross-linking that stiffens the cornea to halt progression of keratoconus.

Mapping of corneal curvature; essential for diagnosing keratoconus and planning refractive surgery.

Fluffy white retinal lesion representing ischaemic infarct of the nerve fibre layer; seen in HTN, DM, HIV, vasculitis.

Clinical test for ocular alignment distinguishing tropias from phorias using monocular and alternate covering.

Small disc with small cup ("disc at risk"); predisposes to non-arteritic AION.

Difference of ≥0.2 between the two eyes; suggestive of glaucomatous damage.

Vertical ratio of the optic cup to disc; values above 0.6 or marked asymmetry suggest glaucoma.

Paralysis of the ciliary muscle abolishing accommodation; essential for refraction in young hyperopes.

Cyst-like fluid accumulation in the macula; commonly post-cataract surgery (Irvine-Gass), uveitis, or vein occlusion.

Opportunistic necrotising retinitis (pizza-pie appearance) in immunocompromised hosts; typically with CD4 <50.

Inflammation/infection of the lacrimal sac, usually due to nasolacrimal duct obstruction.

Upper lid retraction at primary gaze; a classical sign of thyroid eye disease.

Time-dependent recovery of retinal sensitivity in the dark mediated initially by cones and later by rods.

Pigmented border separating attached from detached retina; indicates a chronic retinal detachment.

Branching epithelial defect with terminal end-bulbs that stains with fluorescein; pathognomonic of HSV keratitis.

Basement membrane of the corneal endothelium; thickens with age and bulges as descemetocoele under raised pressure.

Bulging of Descemet membrane through a corneal stromal defect; precursor to perforation.

Macular thickening from leakage of incompetent retinal capillaries; first-line treatment is intravitreal anti-VEGF.

Microvascular complication of diabetes with non-proliferative and proliferative stages defined by ETDRS criteria.

Double vision; binocular (resolves with monocular occlusion) suggests strabismus, monocular suggests refractive or media cause.

Hyaline calcific deposits in the optic nerve head producing pseudopapilloedema; visible on B-scan and FAF.

End-stage fibrovascular subretinal scar of treated or untreated neovascular AMD.

Temporally displaced optic disc and macula seen in retinopathy of prematurity, FEVR, and Toxocara granuloma.

Extracellular deposits between RPE basement membrane and Bruch membrane; hallmark of dry AMD.

Multifactorial ocular surface disorder of tear film homeostasis; aqueous-deficient or evaporative subtypes.

Partial-thickness corneal transplant techniques that replace diseased endothelium with donor tissue, used in Fuchs and pseudophakic bullous keratopathy.

Congenital aberrant innervation of the lateral rectus by CN III causing limited abduction and globe retraction on adduction.

Progressive corneal thinning and bulging following refractive surgery; risk reduced by careful screening with topography and pachymetry.

Outward turning of the eyelid margin causing exposure and epiphora.

Parasympathetic nucleus of CN III in the midbrain that mediates pupillary constriction and accommodation.

Recording of the electrical response of the retina to light; used to diagnose rod-cone dystrophies and other retinal disorders.

Refractive state in which parallel rays focus on the retina without accommodation.

Severe intraocular inflammation, usually infective; post-cataract surgery acute endophthalmitis is most often caused by coagulase-negative staphylococci.

Number of corneal endothelial cells per mm²; normal ~2400-3200, decompensation risk rises below ~500.

Inward turning of the eyelid margin causing the lashes to abrade the cornea.

Surgical removal of the globe with preservation of extraocular muscles for prosthesis support; indicated for malignancy, blind painful eye, or trauma.

Vertical skinfold over the medial canthus; common in children and can mimic esotropia (pseudostrabismus).

Stellate remnant of the pupillary membrane on the anterior lens capsule; benign developmental finding.

Overflow tearing onto the cheek, due to lacrimal hypersecretion or, more commonly, drainage obstruction.

Fibrocellular proliferation on the inner retinal surface causing metamorphopsia and reduced vision; treated by pars plana vitrectomy with membrane peel.

Benign self-limited inflammation of the episclera; differentiate from scleritis by lack of deep pain and blanching with phenylephrine.

Manifest convergent strabismus; types include accommodative, infantile, sensory, and consecutive.

Removal of intraocular contents while preserving the scleral shell; quicker than enucleation but contraindicated if malignancy suspected.

Forward displacement of the globe; most commonly due to thyroid eye disease in adults.

Manifest divergent strabismus; intermittent exotropia is the commonest paediatric form.

Yellow lipid deposits in the outer retina from chronic leakage; ring patterns surround leaking microaneurysms in diabetes.

Detachment due to subretinal fluid without a break or traction; causes include VKH, posterior scleritis, choroidal tumour, malignant HTN.

Benign bone disorder that may involve orbital bones producing proptosis and compressive optic neuropathy.

Includes buttonhole, free cap, epithelial ingrowth, and diffuse lamellar keratitis; managed by lifting and irrigation or steroids.

Vitreous opacities perceived as drifting specks; sudden onset with flashes warrants retinal examination for tear/detachment.

Intravenous dye study mapping retinal/choroidal circulation; detects leakage, ischaemia, and neovascularisation.

Capillary-free central area of the fovea (~0.5 mm); preserved on OCT-angiography and enlarged in ischaemic retinopathies.

Underdevelopment of the foveal pit; associated with albinism, aniridia, and PAX6 mutations; produces nystagmus and reduced acuity.

Striking perivascular sheathing of retinal vessels; associated with CMV (in HIV), Behçet, and idiopathic causes.

Bilateral, slowly progressive corneal endothelial dystrophy with guttata, stromal oedema, and decreased vision on awakening.

Imaging modality detecting lipofuscin in the RPE; useful in geographic atrophy, Stargardt, and other dystrophies.

Sharply demarcated areas of RPE and outer-retinal loss in advanced dry AMD with progressive central scotoma.

Dominant parietal lobe syndrome with agraphia, acalculia, finger agnosia, and right-left disorientation; may include alexia.

Open-angle glaucoma caused by degenerated red cells (khaki ghost cells) obstructing the trabecular meshwork after vitreous haemorrhage.

Chronic progressive optic neuropathy with characteristic optic disc cupping and visual field loss in the presence of an open angle.

Microvacuoles within hydrophobic acrylic IOLs visible at the slit lamp; usually visually insignificant.

Kinetic manual perimetry useful for mapping peripheral defects and patients unable to perform static perimetry.

Contact-lens examination of the anterior chamber angle; the gold standard for differentiating open from closed angles.

TGFBI-related autosomal-dominant dystrophy with breadcrumb-like deposits; recurs after corneal grafting.

Uveitis with mutton-fat keratic precipitates and iris nodules; differential includes sarcoidosis, TB, syphilis, VKH, and sympathetic ophthalmia.

Horizontal breaks in Descemet membrane in congenital glaucoma due to corneal stretching.

Clip-on lens holder used to over-refract over a patient’s existing spectacles.

Rigid gas-permeable lens correcting irregular astigmatism; the optical workhorse in keratoconus.

Peripheral age-related excrescences of Descemet membrane; benign analogue of central corneal guttata.

Visual field loss of half the field; bitemporal indicates chiasmal compression, homonymous indicates retrochiasmal lesion.

Principle that yoke muscles in both eyes receive equal and simultaneous innervation, producing conjugate movements.

Reactivation of VZV in the ophthalmic division of CN V; Hutchinson sign (tip-of-nose lesion) predicts globe involvement.

Plot of ocular motility used to map and follow extraocular muscle palsies.

Difference in iris colour between the two eyes; causes include congenital Horner, Fuchs heterochromic iridocyclitis, melanoma, and Waardenburg.

Rhythmic spontaneous oscillations of pupil size unrelated to stimulation; usually a benign physiological phenomenon.

Tonic pupil with diminished deep tendon reflexes, often in young women.

Acute suppurative infection of an eyelid gland; external (Zeis/Moll) or internal (meibomian).

Triad of mild ptosis, miosis, and ipsilateral anhidrosis from sympathetic chain interruption.

Standard automated perimeter delivering static stimuli; 24-2 and 10-2 patterns are core glaucoma tests.

Vestigial fetal artery; persistence causes Mittendorf dot, Bergmeister papilla, or persistent fetal vasculature (PFV).

Far-sightedness in which parallel rays focus behind the retina; corrected with convex (+) lenses.

Spectrum of retinal vascular changes from arteriolar narrowing to flame haemorrhages and papilloedema in malignant hypertension.

Blood in the anterior chamber, commonly post-traumatic; risk of rebleed and raised IOP within first week.

Layered leukocytes in the anterior chamber; classically seen in HLA-B27 uveitis, Behçet, and infectious endophthalmitis.

Iridocorneal-endothelial syndrome: unilateral corneal endothelial proliferation, iris atrophy and secondary glaucoma in young women.

Synthetic lens implanted to replace the natural lens after cataract surgery; available monofocal, toric, EDOF, and multifocal designs.

Pressure exerted by aqueous humour; mean ~15.5 mmHg, upper normal ~21 mmHg.

Disinsertion of the iris from its root, usually post-traumatic; may produce a second pupil and glare.

Splitting of the anterior iris stroma into shredded strands; typically bilateral in elderly patients.

Nd:YAG laser opening in the peripheral iris that equalises pressure between anterior and posterior chambers, treating pupillary block.

Anterior bowing of the iris due to pupillary block from 360° posterior synechiae, causing acute IOP rise.

Inflammation of the iris; the major component of anterior uveitis with cells, flare, and ciliary injection.

Pseudo-isochromatic colour vision plates screening for red-green deficiency.

Two-step fluorescein dye test assessing patency of the nasolacrimal drainage system.

Chronic anterior uveitis often asymptomatic in young girls with oligoarticular ANA-positive JIA; needs routine screening.

Brown-green peripheral copper ring at Descemet membrane; diagnostic of Wilson disease.

Cellular deposits on corneal endothelium in uveitis; fine in non-granulomatous, large "mutton-fat" in granulomatous disease.

Progressive non-inflammatory thinning and conical protrusion of the cornea producing irregular myopic astigmatism.

Corneal melting from severe vitamin A deficiency; a major preventable cause of childhood blindness.

Measurement of corneal curvature in two principal meridians; essential for IOL calculations and contact lens fitting.

Corneal transplantation; penetrating (PKP) replaces full thickness, while DSAEK/DMEK and DALK replace specific layers.

Prism-based measurement of strabismus angle by centring corneal light reflexes.

Tubuloacinar gland in the superotemporal orbit producing aqueous tears; innervated by parasympathetic fibres via CN VII.

Diagnostic irrigation of the lacrimal system to assess patency in epiphora.

Laser-Assisted In Situ Keratomileusis: corneal flap creation followed by excimer ablation to correct refractive error.

Amyloid deposition in branching refractile lattice lines within the stroma; causes recurrent erosions.

Peripheral retinal thinning with overlying liquefied vitreous; predisposes to atrophic holes and retinal detachment.

Severe autosomal recessive retinal dystrophy presenting in infancy with poor vision, nystagmus, and an extinguished ERG.

Mitochondrial DNA disease causing painless sequential bilateral subacute optic neuropathy in young males.

White pupillary reflex; in a child must exclude retinoblastoma, Coats disease, congenital cataract, PFV, and toxocariasis.

Excursion of the upper lid from extreme down- to up-gaze; guides ptosis surgical planning.

Pupil that constricts to near but not to light; causes include Argyll Robertson pupil, dorsal midbrain lesions, and tonic pupil.

Transition zone between cornea and sclera containing the trabecular meshwork and stem cells of the corneal epithelium.

Topographic feature of keratoconus where the symmetric bowtie pattern of astigmatism is distorted by inferior steepening.

X-linked oculocerebrorenal syndrome with congenital cataract, glaucoma, intellectual disability, and renal Fanconi syndrome.

Capsulopalpebral fascia and inferior tarsal muscle that pull the lower lid in downgaze; disinsertion contributes to involutional entropion.

Central retinal area ~5.5 mm in diameter containing the fovea; mediates high-acuity colour vision.

Full-thickness break at the fovea; staged by SD-OCT and treated with vitrectomy plus internal-limiting-membrane peel.

Loss of eyelashes/brows; causes include chronic blepharitis, alopecia areata, sebaceous carcinoma, and leprosy.

Old term for relative afferent pupillary defect (RAPD).

Autosomal-dominant fibrillin-1 disorder; ocular features include superotemporal lens subluxation, axial myopia, retinal detachment.

Ropy mucus discharge of vernal keratoconjunctivitis.

Corneal diameter >13 mm without raised IOP; X-linked, usually bilateral; differentiate from congenital glaucoma.

Sebaceous gland in the tarsal plate producing the lipid layer of the tear film.

Chronic abnormality of meibomian glands producing evaporative dry eye; managed with lid hygiene and warm compresses.

Perception of straight lines as wavy or distorted; indicates macular pathology and is screened with Amsler grid.

Saccular outpouching of retinal capillary; earliest visible sign of diabetic retinopathy.

Corneal diameter <10 mm in an otherwise normal-sized eye; associated with angle-closure glaucoma.

Small disorganised eye, often with coloboma or cataract; may be syndromic (e.g., CHARGE).

Small keratin-filled cysts of the eyelid; benign and removed with simple incision and expression if cosmetically desired.

Drug causing pupillary constriction (e.g., pilocarpine); useful in angle-closure and accommodative esotropia.

Illuminated targets reflected off the cornea by a keratometer; their separation determines corneal curvature.

Remnant of the posterior hyaloid attachment on the posterior lens capsule; benign developmental finding.

Trabeculectomy with adjunctive antimetabolites (5-FU, MMC) or releasable sutures to improve outcomes.

Painful chronic peripheral corneal ulceration of unknown cause; can lead to perforation.

IOL providing simultaneous distance and near foci via diffractive or refractive optics; trades spectacle independence for halos.

Autoimmune disease of the neuromuscular junction; ocular features include variable ptosis, diplopia, fatigability, Cogan lid twitch.

Drug causing pupil dilation (e.g., tropicamide, phenylephrine); used for fundus examination and refraction.

Historical test for occludable angles by pharmacologic dilation; rarely used today.

White feathery patches of retinal nerve fibres with myelin sheath that did not stop at lamina cribrosa; usually asymptomatic.

Near-sightedness where parallel rays focus in front of the retina; corrected with concave (–) lenses.

Non-arteritic AION: painless monocular vision loss with altitudinal field defect in vasculopaths with "discs at risk".

Bony-membranous channel draining tears from the lacrimal sac to the inferior meatus via the valve of Hasner.

Wet form of age-related macular degeneration characterised by choroidal neovascularisation; treated with anti-VEGF injections.

Secondary glaucoma due to new vessels on iris/angle, typically following ischaemic retinal disease such as PDR or CRVO.

Pathologic new vessels on or away from the optic disc in ischaemic retinopathies; indication for PRP ± anti-VEGF.

Autoimmune disorder with aquaporin-4 antibodies producing severe bilateral optic neuritis and transverse myelitis.

Impaired vision in low light; causes include retinitis pigmentosa, vitamin A deficiency, and congenital stationary night blindness.

Glaucomatous optic neuropathy with IOP consistently within statistically normal limits.

Age-related yellow-brown hardening of the lens nucleus producing myopic shift and decreased contrast sensitivity.

Involuntary rhythmic oscillation of the eyes; classified as jerk or pendular, congenital or acquired.

High-resolution non-invasive imaging that produces cross-sectional retinal/anterior segment scans using low-coherence light.

Dye-free OCT-based imaging of retinal and choroidal vasculature; useful in CNV, DR, and macular telangiectasia.

IOP >21 mmHg without glaucomatous optic nerve or visual-field changes; managed based on individual risk assessment.

Spectrum from CIN to invasive squamous cell carcinoma; treated with excision and/or topical chemotherapy (MMC, 5-FU, interferon).

Glaucoma with a gonioscopically open anterior chamber angle, the most common worldwide form.

Paralysis of one or more extraocular muscles producing limited motility and diplopia.

Pale optic disc reflecting loss of axons; classified by aetiology (compressive, hereditary, ischaemic, inflammatory, toxic).

Excavation of the optic disc reflecting loss of neuroretinal rim; vertical elongation and notching are characteristic glaucomatous features.

Childhood low-grade pilocytic astrocytoma of the optic nerve, often associated with neurofibromatosis type 1.

Inflammatory demyelination of the optic nerve presenting with subacute monocular vision loss and pain on eye movement; commonly associated with multiple sclerosis.

Congenital depression in the optic disc; may be complicated by serous macular detachment.

Combination of CN II, III, IV, V1, VI dysfunction from apex lesion; causes diplopia, visual loss, and V1 sensory loss.

Postseptal infection causing proptosis, painful ophthalmoplegia, and reduced vision; usually arising from sinusitis.

Idiopathic orbital inflammatory disease presenting with painful proptosis; responds dramatically to corticosteroids.

Measurement of central corneal thickness; influences IOP interpretation and refractive surgery candidacy.

Scatter laser ablation of ischaemic peripheral retina to induce regression of neovascularisation in PDR and other ischaemic retinopathies.

Bilateral optic disc swelling due to raised intracranial pressure with preserved early vision and enlarged blind spot.

Dorsal midbrain syndrome of upgaze palsy, convergence-retraction nystagmus, light-near dissociation, and lid retraction (Collier sign).

Microsurgical removal of the vitreous via three sclerotomies; used in vitreous haemorrhage, retinal detachment, ERM, macular hole, and endophthalmitis.

Occlusion of the dominant eye to force use of the amblyopic eye; mainstay of amblyopia treatment with atropine penalisation as alternative.

Bilateral inferior corneal thinning producing "against-the-rule" or "crab-claw" astigmatism on topography.

Cataract removal technique using ultrasound to emulsify and aspirate the lens nucleus through a small incision.

Open-angle glaucoma due to leakage of high-molecular-weight lens proteins through an intact capsule of a hypermature cataract.

Secondary angle-closure glaucoma from an intumescent cataract pushing the iris forward.

Liberation of iris pigment depositing on cornea (Krukenberg spindle), TM, and zonules; predisposes to pigmentary glaucoma in young myopic males.

Yellowish bulbar conjunctival elastotic degeneration adjacent to the limbus; benign but may inflame (pingueculitis).

Posterior retinal vessel dilation and tortuosity in retinopathy of prematurity; indicates progressive disease requiring treatment.

Convex lens with positive power used to correct hyperopia, presbyopia, and aphakia.

Late opacification of the posterior lens capsule after cataract surgery, treated with Nd:YAG capsulotomy.

Prominent anteriorly displaced Schwalbe’s line; isolated finding or part of Axenfeld-Rieger spectrum.

Adhesions between iris and anterior lens capsule due to uveitis; may cause pupillary block and iris bombe.

Age-related loss of accommodation due to lens stiffening producing near-vision difficulty from the mid-40s.

Unit of deviation: one prism diopter shifts the image 1 cm at 1 m; key in strabismus measurement.

Advanced diabetic retinopathy with neovascularisation of disc, retina, or iris; risk of vitreous haemorrhage and tractional detachment.

Systemic disorder with dandruff-like material on lens capsule and pupil margin; commonest identifiable cause of secondary open-angle glaucoma.

Triangular fibrovascular growth of conjunctiva onto the cornea, typically from the nasal limbus, associated with UV exposure.

Drooping of the upper eyelid; classified as aponeurotic, myogenic, neurogenic, or mechanical.

Multifocal small chorioretinal lesions in young myopic women; can develop choroidal neovascularisation requiring anti-VEGF.

Relative Afferent Pupillary Defect; objective sign of asymmetric optic-nerve or extensive retinal dysfunction.

Repeated episodes of spontaneous epithelial breakdown, typically on awakening; managed with lubricants, bandage lens, and PTK.

Glistening crystals seen in chronic retinal pathology, talc retinopathy, Bietti dystrophy, and Sjögren reticular dystrophy.

Determination of the dioptric correction needed to focus parallel light on the retina, performed objectively and subjectively.

Ratio of light speed in vacuum to that in a medium; cornea ~1.376, aqueous ~1.336, lens ~1.42.

Procedures that alter corneal or lenticular power to reduce dependence on spectacles (LASIK, PRK, SMILE, phakic IOL, RLE).

Separation of the neurosensory retina from the RPE; rhegmatogenous, tractional, or exudative.

Obstruction of the central or branch retinal vein causing haemorrhages, oedema, and ischaemia; managed with anti-VEGF for macular oedema.

Inherited rod-cone dystrophy with night blindness, bone-spicule pigment, attenuated vessels, and a ring scotoma.

Childhood malignant retinal tumour from mutations in the RB1 gene; presents with leukocoria, strabismus, and Flexner-Wintersteiner rosettes histologically.

Abnormal retinal vascularisation in premature infants exposed to oxygen; treated by laser ablation or anti-VEGF in type 1 disease.

Splitting of the retina into two layers; degenerative (typical/reticular) or juvenile X-linked types.

White-centred retinal haemorrhage; classically seen in bacterial endocarditis, leukaemia, and severe anaemia.

Pigmented line anterior to Schwalbe’s line; classic gonioscopic feature of pseudoexfoliation syndrome.

Multisystem granulomatous disease; ocular involvement most commonly granulomatous anterior uveitis with mutton-fat KPs.

Pigment line anterior to Schwalbe’s line seen on gonioscopy in pigment dispersion and pseudoexfoliation syndromes.

Indentation tonometer that estimates IOP from corneal indentation by a calibrated plunger; largely replaced by applanation.

Termination of Descemet membrane; the anterior border of the trabecular meshwork on gonioscopy.

Tough opaque collagenous outer coat of the eye; thinnest just behind the recti insertions.

Painful inflammation of the sclera, often associated with systemic disease such as rheumatoid arthritis or granulomatosis with polyangiitis.

An area of partial or complete visual loss within an otherwise intact field; central, paracentral, arcuate, or ring.

Localised loss of iris sphincter contraction giving vermiform movements; characteristic of an Adie pupil.

Fluorescein-strip test detecting aqueous leakage from a corneal wound; positive when fluorescein is diluted by streaming aqueous.

Frequency-doubled Nd:YAG (532 nm) laser selectively targeting pigmented trabecular meshwork cells to lower IOP.

Gonioscopic system grading angle width from 0 (closed) to 4 (wide open) based on visible angle structures.

Autoimmune exocrinopathy producing keratoconjunctivitis sicca and xerostomia; associated with anti-Ro/La antibodies.

Bio-microscope providing high-magnification stereoscopic examination of the anterior segment and, with auxiliary lenses, posterior segment.

Standardised visual acuity test using letter optotypes at 6 m; recorded as a fraction (e.g., 6/6).

Visual acuity recorded as testing distance over the smallest letter size read; equivalent logMAR values are increasingly preferred.

Non-contact imaging quantifying corneal endothelial cell density, size variability (CV), and hexagonality.

Air sinus posterior to the orbital apex; infection or mucocele may compress the cavernous sinus or optic nerve.

Autosomal-recessive juvenile macular dystrophy (ABCA4 gene) with flecks, beaten-bronze macula, and dark choroid on FA.

Binocular depth perception requiring fusion of disparate retinal images; tested by Titmus, TNO, Lang, and Frisby tests.

Severe mucocutaneous hypersensitivity reaction with ocular surface inflammation, symblepharon, and long-term limbal stem cell deficiency.

Ocular misalignment; concomitant or incomitant, paralytic or restrictive.

Adhesion between bulbar and palpebral conjunctiva; seen after chemical burns, Stevens-Johnson, and trachoma.

Bilateral granulomatous panuveitis following penetrating injury or intra-ocular surgery to one ("exciting") eye.

Surgical or laser breaking of synechiae to restore aqueous flow and iris mobility.

Tri-layered film of mucin (goblet cells), aqueous (lacrimal gland) and lipid (meibomian glands) maintaining ocular surface health.

Topical ester anaesthetic used for tonometry and minor surface procedures; longer acting and more painful on instillation than proparacaine.

Autoimmune orbitopathy of Graves disease producing proptosis, lid retraction, restrictive myopathy, and compressive optic neuropathy.

Measurement of intraocular pressure; Goldmann applanation is the clinical gold standard.

Sterile post-cataract inflammation appearing within 24-48h; due to chemical contaminants on instruments or fluids.

Nematode infection (dog roundworm) causing posterior pole or peripheral granuloma with traction in children; differentiate from retinoblastoma.

Most common cause of posterior uveitis worldwide; recurrent focal necrotising retinitis adjacent to old pigmented scar.

Sieve-like tissue at the iridocorneal angle through which 70-90% of aqueous humour drains into Schlemm’s canal.

Filtering glaucoma surgery creating a guarded fistula between the anterior chamber and subconjunctival space.

Mucin-secreting cells of conjunctiva responsible for the inner layer of the tear film.

Brief greying-out of vision in papilloedema, especially on standing; a sentinel symptom of IIH.

Misdirected eyelashes that rub the cornea, producing irritation and abrasion; treated by epilation, electrolysis, or cryotherapy.

Manual kinetic perimetry technique used historically for detailed field mapping.

Scattering of slit-lamp light by anterior chamber protein and cells; basis for grading flare and cells in uveitis.

Two-dimensional ophthalmic ultrasound useful when media is opaque to view posterior segment, masses, and retinal detachment.

High-frequency (35–50 MHz) ultrasound providing detailed images of anterior segment structures including ciliary body and angle.

Pigmented vascular middle coat of the eye, comprising iris, ciliary body, and choroid.

Inflammation of any part of the uveal tract; classified by anatomy (anterior/intermediate/posterior/pan) and aetiology.

Slit-lamp estimate of peripheral anterior chamber depth comparing chamber-to-cornea thickness ratio at the limbus.

Benign acquired peripheral retinal vascular tumour producing exudation; commonly idiopathic or secondary to chronic uveitis or RP.

Disjunctive eye movement that turns the eyes inward (convergence) or outward (divergence) to maintain single vision.

Light-activated drug therapy producing localised vascular occlusion; used in chronic CSCR, PCV, and certain choroidal tumours.

Anti-epileptic causing bilateral concentric visual-field loss; requires periodic perimetric monitoring.

Mapping of peripheral and central visual sensitivity; standard automated perimetry (SAP) is used in glaucoma and neuro-ophthalmology.

Brand name for verteporfin used in photodynamic therapy.

Blood within the vitreous cavity; commonest causes are PDR, PVD-related tear, RVO, and trauma.

Gel-like substance (mostly water with hyaluronic acid and collagen) filling the posterior segment; liquefies and detaches with age.

Autoimmune disease against melanocytes causing bilateral granulomatous panuveitis with exudative RDs, vitiligo, poliosis, and meningism.

Upper lid lag on downgaze; classic sign of thyroid eye disease.

Autosomal-recessive copper metabolism disorder; ocular signs include Kayser-Fleischer ring and sunflower cataract.

Astigmatism with the steepest meridian vertical (near 90°); the commonest form in young patients.

Red-green filter test assessing sensory binocular status: fusion, suppression, or diplopia.

Yellow lipid plaques of the eyelids; may indicate dyslipidaemia and warrants lipid screening.

Ocular surface dryness due to vitamin A deficiency; spectrum from night blindness to Bitot spots and keratomalacia.

Nd:YAG photodisruption of posterior capsule opacification restoring visual axis clarity after cataract surgery.

Modified sebaceous gland associated with eyelash follicles; infection produces an external hordeolum.

Fibrous ring at the orbital apex giving origin to the four rectus muscles and surrounding the optic foramen.

Fibres of the suspensory ligament of Zinn connecting ciliary body to the lens equator; mediate accommodation and are weakened in pseudoexfoliation.