Pathognomonic Signs in Ophthalmology: True and Near-Pathognomonic
Last updated: October 2026
A pathognomonic sign is so characteristic of one disease that finding it makes the diagnosis (Greek pathos, disease, and gnōmōn, indicator). True examples are rare, so examiners love them. This page separates the signs that really are pathognomonic from those that are only very suggestive.
Cornea and external eye
| Sign | Disease |
|---|---|
| Herbert pits (scarred limbal follicles) | Trachoma |
| Giant cobblestone papillae of the upper tarsus | Vernal keratoconjunctivitis |
| Radial keratoneuritis (perineuritis) | Acanthamoeba keratitis |
| Beaded corneal nerves (and iris pearls) | Leprosy |
| Iridescent needle-shaped corneal crystals from age 1 | Cystinosis |
| Corneal curvature equal to the sclera (flat cornea) | Cornea plana |
| Branching "pipestem" refractile lines in the stroma | Lattice corneal dystrophy |
| Saw-toothed (curly) fibres replacing Bowman layer on histology | Thiel–Behnke dystrophy |
| Unilateral painless lid oedema (Romaña sign) | Chagas disease |
Uvea and retina
| Sign | Disease |
|---|---|
| Diffuse stellate KPs over the whole endothelium with fine filaments, no synechiae | Fuchs uveitis syndrome |
| Snowbanks over the inferior pars plana | Pars planitis |
| Active retinochoroiditis next to an old pigmented scar | Toxoplasmosis |
| Transient foveal granularity (orange dots) | MEWDS |
| Subretinal tracks of RPE depigmentation | Internal ophthalmomyiasis |
| Perimacular crater-like retinal folds with multilayered haemorrhage | Abusive head trauma (shaken baby) |
| Avulsion of the vitreous base | Ocular contusion (blunt trauma) |
| Grape-like cysts with fluid–fluid levels on MRI | Orbital lymphatic malformation |
Systemic signs with eye relevance
| Sign | Disease |
|---|---|
| Erythema migrans | Lyme disease |
| Heliotrope eyelid rash (with Gottron papules) | Dermatomyositis |
| Ash-leaf macules under a Wood lamp | Tuberous sclerosis |
| Oculomasticatory myorhythmia | Whipple disease |
Often called pathognomonic, but not quite
| Sign | Disease | Why it is not strictly pathognomonic |
|---|---|---|
| Jaw claudication | Giant cell arteritis | The most specific symptom, but also seen in other vasculitides |
| Dark choroid on FA | Stargardt disease (ABCA4) | Present in most but not all, and absent in dominant forms |
| Sub-RPE infiltrates | Primary vitreoretinal lymphoma | Highly suggestive; biopsy is still needed |
| Pink iris nodules | Syphilitic uveitis | Rare and suggestive |
| Early blocking with late leakage on FA | Neovascular AMD | Characteristic pattern, not a pathognomonic sign |
| Busacca nodules | Granulomatous uveitis | Point to a group of diseases, not one |
| Polymorphous vesicles and bands on specular microscopy | Posterior polymorphous dystrophy | Characteristic; ICE syndrome can look similar |
Related: Triads in ophthalmology, Eponymous signs, Spot the diagnosis (200 cases).
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📘 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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