Classifications in Ophthalmology: 53 Systems in Tables
Last updated: October 2026
A quick-reference page for 53 classification systems used in ophthalmology, grouped by subspecialty and laid out as tables for revision before exams, ward rounds and clinics. For grading and staging scales (Roper-Hall, ICDR, Shaffer, ICROP3 and more), see the companion page Gradings & Stagings in Ophthalmology.
Revise with flip cards
53 cards, one per classification. Recall the categories, then tap the card to check. Use Shuffle for random revision.
Cornea, Conjunctiva & Sclera
- Keratorefractive surgical procedures (by mechanism and depth)
- Corneal dystrophies: IC3D anatomical classification (Edition 3, 2024)
- Herpes simplex keratitis (Holland and Schwartz)
- Dry eye disease: aetiological classification (TFOS DEWS II)
- Blepharitis
- Scleritis (Watson and Hayreh)
- Spheroidal degeneration (climatic droplet keratopathy): types
- Chemical injury: Hughes classification (historical)
Keratorefractive surgical procedures (by mechanism and depth)
Every corneal refractive procedure changes corneal curvature by adding tissue, removing tissue, relaxing it, or shrinking (coagulating or compressing) it, at one of three depths.
| Depth | Addition | Subtraction | Relaxation | Coagulation / compression |
|---|---|---|---|---|
| Superficial | Epikeratophakia; synthetic epikeratophakia | PRK, LASEK, Epi-LASIK, transepithelial PRK; PTK | — | Corneal moulding (orthokeratology) |
| Intrastromal | Keratophakia; corneal inlays (e.g. small-aperture and refractive inlays) | LASIK (microkeratome or femtosecond), keratomileusis, SMILE and other lenticule extraction | Lamellar keratotomy | — |
| Peripheral cornea | Intracorneal ring segments | Wedge resection | Radial, hexagonal and arcuate keratotomy; limbal relaxing incisions | Thermokeratoplasty (LTK, conductive keratoplasty); compression sutures |
More: Refractive surgery for residents
Corneal dystrophies: IC3D anatomical classification (Edition 3, 2024)
| Group | Main members |
|---|---|
| Epithelial and subepithelial | Epithelial basement membrane, epithelial recurrent erosion (COL17A1), Meesmann (KRT3/KRT12), Lisch (MCOLN1, autosomal dominant), gelatinous drop-like (TACSTD2, recessive), subepithelial mucinous |
| Epithelial–stromal TGFBI | Reis–Bücklers (R124L), Thiel–Behnke (R555Q), lattice type 1 (R124C) and lattice variants, granular type 1 (R555W), granular type 2 / Avellino (R124H) |
| Stromal | Macular (CHST6, recessive), Schnyder (UBIAD1), congenital stromal (DCN), fleck (PIKFYVE), posterior amorphous, central cloudy of François, pre-Descemet and PPPCD (PRDX3) |
| Endothelial | Fuchs (TCF4 repeat; COL8A2 early onset), posterior polymorphous (OVOL2, ZEB1, GRHL2), congenital hereditary endothelial (SLC4A11, recessive), X-linked endothelial |
Each dystrophy also carries an evidence category from 1 (gene and locus known) to 4 (suspected new dystrophy).
More: Corneal dystrophies made easy
Herpes simplex keratitis (Holland and Schwartz)
| Type | Forms | Treat with |
|---|---|---|
| Infectious epithelial keratitis | Dendritic, geographic and marginal ulcers (live virus) | Antivirals; no steroid |
| Neurotrophic keratopathy | Punctate erosions to persistent epithelial defect and melt (reduced sensation) | Lubrication, healing measures; avoid toxic drops |
| Stromal keratitis | Necrotising (live virus + inflammation) or immune (interstitial) stromal keratitis | Steroid plus antiviral cover |
| Endotheliitis | Disciform, diffuse or linear (immune reaction at the endothelium) | Steroid plus antiviral cover |
More: Dendritic ulcers
Dry eye disease: aetiological classification (TFOS DEWS II)
Dry eye is a continuum; most patients have features of both types.
| Type | Subtypes and causes |
|---|---|
| Aqueous-deficient | Sjögren syndrome; non-Sjögren (lacrimal gland disease or obstruction, reflex block, systemic drugs, age) |
| Evaporative: intrinsic | Meibomian gland dysfunction, disorders of lid aperture or lid–globe congruity, low blink rate (screen use, Parkinson disease) |
| Evaporative: extrinsic | Vitamin A deficiency, topical drugs and preservatives, contact lens wear, allergic eye disease |
More: Dry eye (TFOS DEWS III)
Blepharitis
| Type | Features |
|---|---|
| Anterior | Lash base: staphylococcal (collarettes, madarosis) or seborrhoeic (greasy scales); Demodex gives cylindrical dandruff |
| Posterior (meibomian gland dysfunction) | Capped or inspissated glands, frothy tears, lid margin telangiectasia; often with rosacea |
| Mixed | Both features; the commonest presentation |
Scleritis (Watson and Hayreh)
| Type | Features |
|---|---|
| Anterior diffuse | Widespread inflammation; the commonest and mildest |
| Anterior nodular | Immobile, tender scleral nodule |
| Anterior necrotising with inflammation | Severe pain, avascular patches; strongly linked to systemic vasculitis (rheumatoid arthritis, GPA) |
| Anterior necrotising without inflammation (scleromalacia perforans) | Painless thinning in long-standing rheumatoid arthritis |
| Posterior | Pain, proptosis, choroidal folds, exudative detachment; T-sign on B-scan |
Episcleritis is separate: simple (sectoral or diffuse) or nodular, blanches with phenylephrine and is rarely sight-threatening.
Spheroidal degeneration (climatic droplet keratopathy): types
| Type | Features |
|---|---|
| Type 1 (primary) | Bilateral, corneal, with no other eye disease (grades in the gradings page) |
| Type 2 (secondary) | Cornea, with another eye disease (scarring, inflammation) |
| Type 3 (conjunctival) | Conjunctival deposits; may occur with types 1 and 2 |
Chemical injury: Hughes classification (historical)
| Grade | Cornea | Conjunctiva / sclera | Prognosis |
|---|---|---|---|
| Mild | Epithelial erosion, faint haze | No ischaemic necrosis | Good |
| Moderately severe | Opacity blurs iris details | Minimal ischaemic necrosis | Guarded |
| Very severe | Pupil outline blurred | Blanching of conjunctiva and sclera | Poor |
In current practice use the Roper-Hall or Dua grading: see the Roper-Hall and Dua tables.
More: Chemical injury
Lens & Cataract
Cataract by morphology
| Group | Types |
|---|---|
| Congenital and developmental | Lamellar (zonular, commonest; often with riders), nuclear, anterior and posterior polar, sutural (Y-shaped), coronary, cerulean (blue dot), total, membranous, posterior lenticonus |
| Age-related | Nuclear sclerotic, cortical (spokes and wedges), posterior subcapsular, mixed |
| Secondary and complicated | Steroid-induced and uveitic (PSC), diabetic snowflake, myotonic (Christmas tree), Wilson sunflower, traumatic rosette, glassblower (true exfoliation), radiation, electrical |
| By maturity | Immature, intumescent, mature, hypermature (Morgagnian) |
More: Congenital cataract
Ectopia lentis: causes
| Group | Examples | Typical direction |
|---|---|---|
| Trauma | Blunt injury (commonest overall) | Any |
| Isolated hereditary | Simple ectopia lentis, ectopia lentis et pupillae | Varies |
| With systemic disease | Marfan syndrome | Upwards and outwards |
| Homocystinuria | Downwards and inwards | |
| Weill–Marchesani (microspherophakia) | Forwards (pupil block) | |
| Sulfite oxidase deficiency, Ehlers–Danlos | Varies | |
| Ocular conditions | Pseudoexfoliation, high myopia, buphthalmos, aniridia, hypermature cataract | Varies |
Intraocular lenses
| Basis | Types |
|---|---|
| Position | Anterior chamber (angle-supported), iris-fixated (claw), posterior chamber (in the bag, sulcus, scleral-fixated) |
| Material | Hydrophobic acrylic, hydrophilic acrylic, silicone, PMMA (rigid) |
| Optics | Monofocal, enhanced monofocal, toric, multifocal (bifocal, trifocal), extended depth of focus (EDOF), light-adjustable |
| Phakic IOLs | Posterior chamber (ICL), iris-fixated, angle-supported |
More: IOL types guide
Glaucoma
- Primary angle-closure disease (ISGEO, updated)
- Angle closure by mechanism (level of the block)
- Spaeth gonioscopic classification
- Childhood glaucoma: Childhood Glaucoma Research Network (CGRN) classification
- Glaucoma: broad classification
Primary angle-closure disease (ISGEO, updated)
| Stage | Definition |
|---|---|
| Primary angle-closure suspect (PACS) | Iridotrabecular contact for at least 180° (originally 270°) on gonioscopy; normal IOP, no PAS, no optic neuropathy |
| Primary angle closure (PAC) | PACS plus raised IOP and/or peripheral anterior synechiae; no glaucomatous optic neuropathy |
| Primary angle-closure glaucoma (PACG) | PAC plus glaucomatous optic neuropathy and field loss |
| Acute angle closure | A symptomatic attack (pain, haloes, high IOP, mid-dilated pupil) at any stage |
ZAP and ANA-LIG showed most PACS eyes do not progress, so prophylactic iridotomy is no longer automatic for PACS.
More: Angle closure
Angle closure by mechanism (level of the block)
| Level | Mechanism | Examples | Treatment |
|---|---|---|---|
| Iris | Pupil block | Primary angle closure, iris bombé, microspherophakia | Laser iridotomy |
| Ciliary body | Anteriorly placed ciliary processes push the iris forward | Plateau iris; ciliary body cysts; ciliochoroidal effusion (topiramate) | Iridoplasty, lens extraction, stop the drug |
| Lens | Large or forward lens | Phacomorphic glaucoma, lens subluxation | Lens extraction |
| Behind the lens | Posterior pushing | Aqueous misdirection, suprachoroidal haemorrhage, tumours, scleral buckle | Cycloplegia, vitrectomy, treat the cause |
Spaeth gonioscopic classification
| Component | Grades |
|---|---|
| Iris insertion | A: anterior to Schwalbe line; B: behind Schwalbe line (at the trabecular meshwork); C: at the scleral spur; D: deep (ciliary body band); E: extremely deep |
| Angle width | Angle between the iris surface and the trabecular meshwork, in degrees (0–40°+) |
| Peripheral iris configuration | s: steep (convex); r: regular (flat); q: queer (concave, as in pigment dispersion); plateau and bowed variants added later |
| Trabecular pigmentation | 0 (none) to 4+ (heavy) |
Written as e.g. C30r 2+. Record appositional (in brackets) and indented findings separately. See also Shaffer grading.
More: Gonioscopy grading
Childhood glaucoma: Childhood Glaucoma Research Network (CGRN) classification
| Group | Includes |
|---|---|
| Primary congenital glaucoma | Neonatal (birth to 1 month), infantile (1–24 months), late-onset (over 2 years); spontaneously arrested cases |
| Juvenile open-angle glaucoma | Onset after 4 years, normal-looking angle, no buphthalmos |
| Secondary: non-acquired ocular anomalies | Axenfeld–Rieger, Peters anomaly, aniridia, congenital ectropion uveae |
| Secondary: non-acquired systemic disease | Sturge–Weber, neurofibromatosis, Marfan, Lowe, congenital rubella |
| Secondary: acquired conditions | Uveitis, trauma, steroids, tumours, ROP |
| Glaucoma following cataract surgery | Open- or closed-angle glaucoma after childhood cataract removal |
More: Congenital glaucoma
Glaucoma: broad classification
| Group | Examples |
|---|---|
| Primary open-angle | POAG, normal-tension glaucoma, ocular hypertension (suspect) |
| Primary angle-closure | PACS, PAC, PACG (see above) |
| Secondary open-angle | Pseudoexfoliative, pigmentary, steroid-induced, uveitic, angle recession, phacolytic, raised episcleral venous pressure, ghost cell |
| Secondary angle-closure | Neovascular, ICE syndrome, uveitic with synechiae, phacomorphic, aqueous misdirection |
| Childhood | CGRN classification above |
More: Glaucoma hub
Retina & Vitreous
- Retinal detachment: types
- Giant retinal breaks
- Macular neovascularisation (CONAN 2020)
- Retinal vein occlusion
- Macular telangiectasia (Yannuzzi 2006) and MacTel type 2 stages (Gass–Blodi)
- Central serous chorioretinopathy
- Radiation retinopathy (Finger)
- Coats disease: Reese types (historical)
- Stickler syndrome
- Colour vision deficiency
- Drusen size
- Posterior vitreous detachment
Retinal detachment: types
| Type | Mechanism | Clues |
|---|---|---|
| Rhegmatogenous | Fluid passes through a retinal break | Tobacco dust, corrugated mobile retina, break found |
| Tractional | Fibrovascular membranes pull the retina | Concave, immobile; PDR, ROP, penetrating trauma |
| Exudative (serous) | Fluid leaks from choroid or retinal vessels; no break | Smooth, convex, shifting fluid; VKH, tumours, posterior scleritis, toxaemia |
| Combined tractional–rhegmatogenous | Traction creates a break | Convex areas in a tractional detachment; progresses fast |
More: Retinal detachment guide
Giant retinal breaks
| Type | Description |
|---|---|
| Giant retinal tear | Tear of 90° (3 clock hours) or more, usually at the posterior vitreous base; record extent, location, flap (flat, rolled or inverted), radial extensions, PVR and cause |
| Giant dialysis | Disinsertion at the ora serrata, usually after trauma; the vitreous stays attached to the posterior edge |
| Giant retinotomy | Surgical relaxing retinotomy of 90° or more |
Macular neovascularisation (CONAN 2020)
| Type | Location | Old name and examples |
|---|---|---|
| Type 1 | Under the RPE | Occult CNV; includes polypoidal choroidal vasculopathy (aneurysmal type 1) |
| Type 2 | Above the RPE (subretinal) | Classic CNV; myopic, inflammatory CNV |
| Type 3 | Within the retina, from the deep capillary plexus | Retinal angiomatous proliferation |
| Mixed | Types 1 and 2 together | Minimally classic / predominantly classic in old terms |
More: AMD
Retinal vein occlusion
| Type | Subtypes |
|---|---|
| Central (CRVO) | Non-ischaemic (perfused) or ischaemic: 10 or more disc areas of capillary non-perfusion (CVOS); a third of non-ischaemic convert |
| Hemiretinal / hemispheric | Occlusion of a superior or inferior trunk at or near the disc |
| Branch (BRVO) | Major branch (at the disc or along the arcade), macular branch, or peripheral branch not involving the macula; usually at an arteriovenous crossing |
More: Retina hub
Macular telangiectasia (Yannuzzi 2006) and MacTel type 2 stages (Gass–Blodi)
| Type / stage | Features |
|---|---|
| Type 1: aneurysmal | Unilateral, men; visible telangiectasia and exudates (Coats spectrum) |
| Type 2: perifoveal | Bilateral, middle age; loss of retinal transparency, crystals, right-angle venules, outer retinal cavitation on OCT |
| Type 3: occlusive | Rare; capillary occlusion with systemic disease |
| MacTel 2 stage 1–2 | Faint parafoveal leakage on FFA; then greying of the parafoveal retina |
| MacTel 2 stage 3 | Right-angle venules |
| MacTel 2 stage 4 | Intraretinal pigment plaques |
| MacTel 2 stage 5 | Subretinal neovascularisation |
Central serous chorioretinopathy
| Basis | Categories |
|---|---|
| Course (traditional) | Acute (resolves within about 3–6 months), chronic (persistent fluid or widespread RPE change), recurrent |
| CSCR International Group (2020) | Simple (RPE change of 2 disc areas or less), complex (more than 2 disc areas), atypical (bullous detachment, large PED, etc.); each described as primary, recurrent, persistent or resolved |
More: CSCR
Radiation retinopathy (Finger)
| Stage | Findings |
|---|---|
| 1 | Changes outside the macula: microaneurysms, haemorrhages, cotton wool spots, exudates, ghost vessels, choroidopathy; retinal ischaemia under 5 disc areas |
| 2 | Stage 1 findings within the macula |
| 3 | Stage 1–2 plus macular oedema or retinal neovascularisation |
| 4 | Stage 1–3 plus vitreous haemorrhage or retinal ischaemia over 5 disc areas |
Coats disease: Reese types (historical)
| Type | Features |
|---|---|
| I | Exudation without visible vascular change |
| II | Exudation with abnormal (telangiectatic) vessels |
| III | Exudation around a large retinal angioma |
Today Coats disease is staged with the Shields staging in the gradings page.
More: Leukocoria
Stickler syndrome
| Type | Gene | Features |
|---|---|---|
| Type 1 (commonest) | COL2A1 | Membranous (type 1) vitreous anomaly; high myopia, giant retinal tears; midline cleft, deafness, arthropathy |
| Type 2 | COL11A1 | Beaded (type 2) vitreous; more hearing loss |
| Non-ocular type | COL11A2 | Systemic features only (the gene is not expressed in the eye) |
| Recessive types | COL9A1, COL9A2, COL9A3 and others | Rare; high myopia, deafness |
Prophylactic 360° cryotherapy or laser is often advised in type 1 to reduce retinal detachment risk.
More: Genes and eye diseases
Colour vision deficiency
| Type | Cone affected | Notes |
|---|---|---|
| Protanopia / protanomaly | L (red) cone absent / anomalous | Red-green; X-linked; reds look dark |
| Deuteranopia / deuteranomaly | M (green) cone absent / anomalous | Red-green; X-linked; deuteranomaly is the commonest (about 5% of men) |
| Tritanopia / tritanomaly | S (blue) cone | Blue-yellow; autosomal dominant; rare |
| Achromatopsia (rod monochromacy) | No functioning cones | Poor acuity, photophobia, nystagmus |
| Blue cone monochromacy | Only S cones and rods | X-linked |
| Acquired (Köllner rule) | — | Outer retina and media disease → blue-yellow defects; optic nerve disease → red-green defects (glaucoma is an exception, often blue-yellow) |
Suffix -opia = dichromacy (one cone class missing); -anomaly = anomalous trichromacy (one cone class shifted). About 8% of men and 0.5% of women have a red-green defect.
More: Colour vision testing guide
Drusen size
| Size | Diameter | Comparison |
|---|---|---|
| Small (hard) | Under 63 µm | Less than half the width of a vein at the disc margin |
| Medium (intermediate) | 63 to under 125 µm | Between small and large |
| Large | 125 µm or more | About the width of a vein at the disc margin |
AMD stages based on drusen and pigment are in the Beckman classification; the AREDS simplified severity scale is also in the gradings page.
More: AMD
Posterior vitreous detachment
| Type | Features |
|---|---|
| Complete PVD | Hyaloid separated from the posterior pole; Weiss ring often seen |
| Partial (incomplete) PVD | Persistent attachment at the fovea (vitreomacular adhesion or traction), disc or vessels |
| Anomalous PVD | Liquefaction without enough separation: vitreoschisis, macular hole, ERM, traction |
OCT staging (Uchino) and clinical stages are in the gradings page.
More: Retinal detachment guide
Uvea
- Uveitis: SUN anatomical classification
- Uveitis by cause (IUSG)
- Granulomatous versus non-granulomatous uveitis
- Endophthalmitis
Uveitis: SUN anatomical classification
| Type | Primary site | Includes |
|---|---|---|
| Anterior | Anterior chamber | Iritis, iridocyclitis, anterior cyclitis |
| Intermediate | Vitreous | Pars planitis, posterior cyclitis, hyalitis |
| Posterior | Retina or choroid | Focal, multifocal or diffuse choroiditis, chorioretinitis, retinochoroiditis, retinitis, neuroretinitis |
| Panuveitis | Anterior chamber, vitreous and retina or choroid | VKH, sympathetic ophthalmia, Behçet, sarcoid, TB, syphilis |
Describe also onset (sudden/insidious), duration (limited ≤3 months or persistent) and course (acute, recurrent, chronic). Grading of cells and flare is in the gradings page.
More: Uveitis made easy
Uveitis by cause (IUSG)
| Group | Examples |
|---|---|
| Infectious | Bacterial (TB, syphilis), viral (HSV, VZV, CMV), fungal, parasitic (toxoplasma, toxocara) |
| Non-infectious, with systemic disease | HLA-B27 spondyloarthropathies, sarcoidosis, Behçet, VKH, JIA, multiple sclerosis |
| Non-infectious, eye only | Birdshot, pars planitis, Fuchs uveitis, sympathetic ophthalmia, white dot syndromes |
| Masquerade | Lymphoma, retinoblastoma, leukaemia, metastases, retinal detachment, intraocular foreign body |
More: Uveitis work-up
Granulomatous versus non-granulomatous uveitis
| Type | Signs | Causes |
|---|---|---|
| Granulomatous | Mutton-fat KPs, Koeppe and Busacca iris nodules, choroidal granulomas | Sarcoid, TB, syphilis, VKH, sympathetic ophthalmia, herpes, toxoplasma, lens-induced |
| Non-granulomatous | Fine KPs, fibrin, hypopyon | HLA-B27, JIA, Behçet, Fuchs uveitis (stellate KPs) |
Endophthalmitis
| Group | Types |
|---|---|
| Exogenous: postoperative | Acute (within 6 weeks: staphylococci, streptococci) and delayed/chronic (after 6 weeks: Cutibacterium, fungi) |
| Exogenous: bleb-related | Early or late after filtering surgery; streptococci and Haemophilus |
| Exogenous: post-traumatic | Open globe, especially with an IOFB; Bacillus cereus |
| Exogenous: post-injection | After intravitreal injection |
| Endogenous | Spread from the blood: Candida, Klebsiella (liver abscess), endocarditis |
More: Endophthalmitis guide
Paediatrics & Strabismus
- Accommodative esotropia
- Duane retraction syndrome (Huber)
- Amblyopia
- Nystagmus (CEMAS)
- Uveal coloboma: classifications
- Albinism
Accommodative esotropia
| System | Types |
|---|---|
| von Noorden (by cause) | Refractive (hyperopia, normal AC/A); non-refractive (high AC/A); hypo-accommodative; partially accommodative |
| CEMAS: pure refractive | Esotropia fully eliminated by hyperopic spectacles |
| CEMAS: non-refractive | Esotropia at near only, eliminated by plus lenses at near (bifocals) |
| CEMAS: mixed | Esotropia at distance, greater at near; responds to distance correction plus bifocal |
| CEMAS: partially accommodative | Hyperopia with incomplete response to spectacles and bifocals |
More: Strabismus hub
Duane retraction syndrome (Huber)
| Type | Abduction | Adduction | Note |
|---|---|---|---|
| 1 (about 80%) | Limited | Normal or near normal | Commonest; often left eye, girls |
| 2 | Normal or slightly limited | Limited | Least common (about 7%) |
| 3 | Limited | Limited | About 15% |
All types show globe retraction and lid narrowing on adduction.
More: Strabismus measurement reference
Amblyopia
| Basis | Categories |
|---|---|
| Cause | Strabismic; anisometropic; isoametropic (bilateral high refractive error); meridional (astigmatic); deprivation (cataract, ptosis, corneal opacity) |
| Severity (PEDIG patching trials) | Moderate: 20/40 to 20/80 (6/12 to 6/24); severe: 20/100 to 20/400 (6/30 to 6/120). ATS1 used 20/40–20/100 for moderate |
More: Amblyopia treatment updates
Nystagmus (CEMAS)
| Type | Features |
|---|---|
| Infantile nystagmus syndrome | Onset in the first months; horizontal, increasing velocity waveform, null point, damps on convergence; idiopathic or with afferent disease |
| Fusion maldevelopment nystagmus syndrome | Latent / manifest latent nystagmus with infantile esotropia; fast phase towards the fixing eye |
| Spasmus nutans syndrome | Asymmetric, small, fast nystagmus with head nodding and tilt; exclude chiasmal glioma |
| Acquired | Vestibular, gaze-evoked, downbeat, upbeat, see-saw, periodic alternating, convergence–retraction |
More: Nystagmus
Uveal coloboma: classifications
| System | Types |
|---|---|
| Ida Mann (1937) | 1: above the disc; 2: at the upper border of the disc; 3: separated from the disc by a narrow band of normal retina; 4: inferior crescent below the disc; 5: isolated gap in the line of the fissure; 6: area of pigment disturbance; 7: extreme peripheral coloboma |
| Gopal et al. (disc in fundal coloboma) | 1: normal disc outside coloboma; 2: abnormal disc outside coloboma; 3: disc outside but separately colobomatous; 4: disc within coloboma, normal; 5: disc within coloboma and colobomatous (commonest, about 44%); 6: disc not identified, vessels from the coloboma's upper edge |
Vision was better in Gopal types 1–3 than 4–6. Retinal detachment is a lifelong risk.
More: Eye embryology made easy
Albinism
| Type | Gene | Features |
|---|---|---|
| OCA1A / OCA1B | TYR | No melanin (1A) or some melanin developing later (1B) |
| OCA2 | OCA2 (P gene) | Commonest worldwide, especially in Africa |
| OCA3 / OCA4 | TYRP1 / SLC45A2 | OCA4 common in Japan |
| Ocular albinism (OA1) | GPR143 | X-linked; eyes affected, skin near normal; carrier mothers have mottled fundi |
| Syndromic | Hermansky–Pudlak, Chédiak–Higashi | Bleeding tendency (HPS); infections (CHS) |
All types: foveal hypoplasia, nystagmus, iris transillumination and excess decussation at the chiasm.
More: Paediatric ophthalmology hub
Neuro-ophthalmology
Third nerve palsy
| Type | Usual cause | Action |
|---|---|---|
| Complete, pupil-sparing | Microvascular ischaemia (diabetes, hypertension) | Observe; image if no recovery by 3 months or atypical |
| Pupil-involving | Compression (posterior communicating aneurysm) | Same-day CTA or MRA |
| Partial with normal pupil | Either | Image and watch closely |
| With aberrant regeneration | Trauma or compression (never ischaemia) | Image |
More: Ocular motility made easy
Horner syndrome by neuron
| Order | Where | Causes |
|---|---|---|
| 1st (central) | Hypothalamus to C8–T2 | Lateral medullary stroke, syrinx, MS |
| 2nd (preganglionic) | Lung apex and neck | Pancoast tumour, neck surgery, neuroblastoma |
| 3rd (postganglionic) | Along the internal carotid | Carotid dissection, cavernous sinus lesions, cluster headache |
More: Pupils made easy
Sturge–Weber syndrome (Roach scale)
| Type | Features | Glaucoma |
|---|---|---|
| I | Facial and leptomeningeal angiomas | May occur |
| II | Facial angioma only | May occur |
| III | Isolated leptomeningeal angioma | Usually none |
More: Glaucoma hub
Optic atrophy
| Type | Appearance | Causes |
|---|---|---|
| Primary | Chalk-white disc, sharp margins | Optic neuritis, compression, trauma, hereditary |
| Secondary | Dirty grey disc, blurred margins, sheathed vessels | After papilloedema or papillitis |
| Consecutive | Waxy pale disc with attenuated vessels | Retinal disease: RP, CRAO, extensive PRP |
| Glaucomatous | Cupped disc with rim loss | Glaucoma |
| Band (bow-tie) | Pallor of the nasal and temporal disc | Chiasmal or optic tract lesions (the eye with temporal field loss) |
More: Neuro-ophthalmology hub
Oculoplasty & Orbit
- Thyroid eye disease: NOSPECS (Werner)
- Thyroid eye disease: EUGOGO severity and VISA
- Orbital infection: Chandler classification
- Ptosis
- Entropion and ectropion
- Orbital fractures
Thyroid eye disease: NOSPECS (Werner)
| Class | Features |
|---|---|
| 0 (N) | No signs or symptoms |
| 1 (O) | Only signs (lid retraction, lag), no symptoms |
| 2 (S) | Soft tissue involvement |
| 3 (P) | Proptosis |
| 4 (E) | Extraocular muscle involvement |
| 5 (C) | Corneal involvement |
| 6 (S) | Sight loss (optic nerve compression) |
NOSPECS is mainly historical; activity is graded by the Clinical Activity Score and severity by EUGOGO (below).
More: Thyroid eye disease
Thyroid eye disease: EUGOGO severity and VISA
| Category | Features | Management |
|---|---|---|
| Mild | Minor impact on life: lid retraction under 2 mm, mild soft-tissue signs, proptosis under 3 mm above normal, transient or no diplopia | Local measures, selenium, observe |
| Moderate-to-severe | Lid retraction 2 mm or more, moderate or severe soft-tissue signs, proptosis 3 mm or more, inconstant or constant diplopia | IV methylprednisolone (with mycophenolate), teprotumumab, orbital radiotherapy |
| Sight-threatening | Dysthyroid optic neuropathy and/or corneal breakdown | Urgent IV steroids, decompression |
| VISA (alternative) | Vision, Inflammation, Strabismus, Appearance graded separately | Treat each domain on its own merits |
More: Thyroid eye disease
Orbital infection: Chandler classification
| Group | Description |
|---|---|
| I | Preseptal cellulitis |
| II | Orbital cellulitis (diffuse orbital inflammation) |
| III | Subperiosteal abscess |
| IV | Orbital abscess |
| V | Cavernous sinus thrombosis |
More: Orbital cellulitis
Ptosis
| Group | Types |
|---|---|
| Congenital | Simple myogenic (dystrophic levator), blepharophimosis syndrome, Marcus Gunn jaw-winking (synkinetic), congenital III palsy, congenital Horner |
| Acquired: aponeurotic | Involutional, contact lens wear, after eye surgery (high lid crease, good levator function) |
| Acquired: neurogenic | Third nerve palsy, Horner syndrome |
| Acquired: myogenic / neuromuscular | Myasthenia gravis, CPEO, myotonic dystrophy, oculopharyngeal muscular dystrophy |
| Acquired: mechanical / traumatic | Lid tumours, scarring, oedema; levator injury |
| Pseudoptosis | Dermatochalasis, enophthalmos, hypotropia, contralateral lid retraction |
Severity and levator function grades are in the gradings page.
More: Blepharoptosis
Entropion and ectropion
| Type | Entropion | Ectropion |
|---|---|---|
| Involutional | Lower lid; laxity, retractor dehiscence, overriding orbicularis | Lower lid; horizontal laxity |
| Cicatricial | Conjunctival scarring (trachoma, pemphigoid, SJS, burns) | Skin scarring or shortage (burns, trauma, sun damage) |
| Paralytic | — | Facial nerve palsy |
| Mechanical | — | Lid mass or oedema pulling the lid down |
| Spastic / acute | Ocular irritation or after surgery | — |
| Congenital | Rare (epiblepharon is more common) | Rare |
More: Oculoplasty hub
Orbital fractures
| Type | Description |
|---|---|
| Pure blowout | Orbital floor (or medial wall) fracture with an intact rim |
| Impure blowout | Associated rim fracture (zygomatic or maxillary) |
| Trapdoor (children) | Linear hinged fracture trapping muscle; white-eyed blowout, oculocardiac reflex: urgent repair |
| Roof | Children (before frontal sinus pneumatisation); CSF leak risk |
| Zygomaticomaxillary complex and Le Fort II/III | Mid-face fractures involving the orbit |
More: Orbital fracture
Trauma
Mechanical eye injury: Birmingham Eye Trauma Terminology (BETT)
| Type | Subtype | Definition |
|---|---|---|
| Closed globe | Contusion | No full-thickness wound; injury from direct blow or shape change |
| Lamellar laceration | Partial-thickness wound of the eye wall | |
| Open globe | Rupture | Full-thickness wound from blunt force (inside-out); often at the limbus or behind the recti |
| Penetrating injury | Single entrance wound from a sharp object | |
| Intraocular foreign body | Retained foreign body with an entrance wound | |
| Perforating injury | Entrance and exit wounds |
Zones and grades of open globe injury are in the gradings page.
More: Open globe injuries
Intraocular foreign bodies
| Basis | Categories |
|---|---|
| Location | Anterior chamber or angle, iris, lens, vitreous, retina or choroid, intraorbital (outside the globe) |
| Material: inert | Glass, plastic, stone, gold, silver, platinum (may be left if quiet and away from the visual axis) |
| Material: toxic | Iron and steel (siderosis), copper (chalcosis; pure copper causes acute sterile endophthalmitis), lead, zinc |
| Material: organic | Wood and vegetable matter: high infection risk (fungi, Bacillus) |
| Magnetic properties | Magnetic (iron, steel) or non-magnetic; avoid MRI until a metallic IOFB is excluded |
Image with CT (not MRI). Remove toxic and organic foreign bodies early.
More: Ocular siderosis
Systemic & Miscellaneous
- Visual impairment (WHO ICD-11, presenting acuity in the better eye)
- Laser safety classes
- Evidence levels used in guidelines
Visual impairment (WHO ICD-11, presenting acuity in the better eye)
| Category | Visual acuity |
|---|---|
| No impairment | 6/12 or better |
| Mild | Worse than 6/12 to 6/18 |
| Moderate | Worse than 6/18 to 6/60 |
| Severe | Worse than 6/60 to 3/60 |
| Blindness | Worse than 3/60, or a central field under 10° radius |
| Near vision impairment | Worse than N6 or M 0.8 at 40 cm |
India's 2018 disability matrix uses its own percentage categories: see the visual disability calculator.
More: Levels of visual impairment
Laser safety classes
| Class | Summary |
|---|---|
| 1 / 1M | Safe (1M: unless viewed through optics) |
| 2 / 2M | Visible, up to 1 mW; blink reflex protects |
| 3R | Up to 5 mW; low risk, avoid staring |
| 3B | Up to 500 mW; direct viewing is hazardous |
| 4 | Over 500 mW; eye, skin and fire hazard (most surgical lasers) |
Full table with notes in the gradings page (IEC 60825-1, which replaced the older US 3A class).
More: Lasers made easy
Evidence levels used in guidelines
| System | Levels |
|---|---|
| ADA | A, B, C, E (expert consensus): see the gradings page |
| Oxford CEBM | Level 1 (systematic reviews of RCTs) to level 5 (mechanism-based reasoning) |
| GRADE | Certainty of evidence: high, moderate, low, very low; recommendations strong or conditional |
More: Biostatistics for ophthalmologists
Key sources
- Weiss JS, et al. IC3D classification of corneal dystrophies, edition 3. Cornea. 2024;43:466-527
- Jabs DA, et al. Standardization of uveitis nomenclature (SUN). Am J Ophthalmol. 2005;140:509-516
- Spaide RF, et al. Consensus nomenclature for neovascular AMD (CONAN). Ophthalmology. 2020;127:616-636
- Kuhn F, et al. Birmingham Eye Trauma Terminology. Ophthalmology. 1996;103:240-243
📘 Want the exam-ready deep dive? This topic, and much more is covered in Ophthalmology Explorer (A High-Yield Clinical Reference for Ophthalmology Residents, Fellows & Board Exams) — available on Kindle. See all my books.
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