Differential Diagnosis 
of 
Common Physical Signs in Iris
Iris neovascularization
(always look at the posterior segment for cause, the first two on the list are the commonest causes)
  • diabetes mellitus
  • central retinal vein occlusion / branch retinal vein occlusion
  • central retinal artery occlusion / branch retinal artery occlusion
  • carotid artery disease
  • chronic uveitis
  • retinal detachment
  • malignant melanoma
  • carotid cavernous fistula
  • retinopathy of prematurity


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    Iris transillumination
    (the patterns of the transillumination may give clues to the possible causes)

        Diffused

  •     Fuch's heterochromic cyclitis
  •     albinism
  •     post-cataract surgery
  •     diabetic mellitus
  •     previous acute glaucoma causing iris ischaemia
    •     Sectorial
  •     herpes zoster
  •     iridoschisis
  •     post-cataract surgery
  •     previous acute glaucoma
  •     iridocorneal-endothelial syndrome
    •     Peripupillary
  •     pseudoexfoliation syndrome
    •     Mid-periphery
  •     pigment dispersion syndrome
    •     Localized
  •     post-trabeculectomy
  •     post-laser iridotomy (both iridectomy and iridotomy are usually found superiorly)
  •     post-vitrectomy with silicone implant (Ando's procedure and the iridectomy is performed inferiorly)


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    Pigmented iris lesion
    (the lesion may be solitary or multiple, the following list is mainly a differential diagnosis of iris naevus)

  • iris naevus
  • iris melanoma (note: both melanoma and naevus can cause corectopia )
  • iris leiomyoma
  • tumour extended from the ciliary body
  • metastatic tumour
  • juvenile xanthogranuloma (classically seen only in young children)
  • iris cyst (which may result from surgery)
  • granuloma (typically in sarcoidosis, termed Koeppe nodules if at the pupil margin and Busacca nodules if at the periphery)
  • Lisch nodules (usually multiple)
  • Brushfield's spots (seen in Down's syndrome and usually multiple)


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    Heterochromia
    (Heterochromia refers to differences in the iris colour. The differences are best seen in day light; the abnormal eye may be hypochromic or hyperchromic. In the examination, the most common conditions with heterochromia are Fuch's heterochromic cyclitis, siderosis bulbi and congenital Horner's syndrome. Cases of iris transillumination mentioned above may also give rise to heterochromia if there is significant pigment loss)

    1) Causes of hypochromia

  • congenital (this may be isolated or associated with systemic features such as Waardenburg's syndrome - hypertelorism, white forelock, white eyelashes, leukoderma and cochlear deafness)
  • congenital Horner's syndrome (sympathetic innervation is important for the migration of the melanosome)
  • Fuch's heterochromic cyclitis
  • Chronic uveitis
  • Post-cataract surgery
    • 2) Causes of hyperchromia
  • congenital (this may be isolated or associated with conditions such as naevus of Ota)
  • siderosis bulbi ( the vision is usually poor and there is absence of pupil reaction to light)
  • diffuse iris naevus / melanoma
  • Sturge-Weber's syndrome
  • rubeosis iridis (differences in iris colour can become obvious if the blood vessels are extensive)
  • drug-induced (latanoprost, there may be associated hypertrichosis of the eyelashes)


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    Corectopia
    (this is diplacement of the pupils)

    • congenital (including coloboma)
    • iris naevus / iris melanoma
    • ectopia uvae
    • ciliary body tumours
    • anterior chamber cleavage syndrome (Axenfeld and Reiger's syndrome)
    • iridocorneal-endothelial syndrome
    • post-cataract surgery (especially with vitreous loss or the haptic is displaced)
    • post-trabeculectomy


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