Details of the anatomy of the iris and the congenital anomalies of the iris.

1. ANATOMY OF IRIS
AND
IT’S CONGENITAL
ANOMALIES
MODERATOR
DR. J. J. KULI
Professor
PRESENTER
DAISYVISHWAKARMA
Post Graduate Student
DEPARTMENT OF OPHTHALMOLOGY
ASSAM MEDICAL COLLEGE & HOSPITAL , DIBRUGARH

2. INTRODUCTIONIRIS -
A circular disc corresponding to diaphragm of a
camera
Lies in the frontal plane of the eye between the
anterior & posterior chamber
At its centre, there is an aperture called PUPIL
Colour comes from microscopic pigment cells
(melanin )
Colour, texture & pattern of each person’s iris is
as unique as a fingerprint

3. DEVELOPMENT
19th day – neural groove
20th day – neural fold
Optic sulcus
22nd day – fusion of neural
fold begins
Closure of neural groove in
cranial & caudal direction
to develop into the neural
tube
Neuroectodermal cells
proliferate from future
crest of neural folds –
population of Neural crest
cells

4. Before closure – optic
sulcus – optic pits –
optic vesicles
31/2 weeks –
appearance of optic
vesicle, grows laterally
to come in contact with
surface ectoderm
Optic stalk is
continuous with
diencephalon – third
ventricle

5. 27th day – lens placode
concurrently optic vesicles are developing
into optic cups
33rd day – lens vesicle separates from surface
ectoderm

6. 5th week (5.5-6 mm) –
development of embryonic fissure
7mm- hyaloid artery enters the
fissure & reaches upto posterior
pole of lens vesicle
6th week (11-12mm) – beginning of
closure of fissure in mid-portion
13-14mm- almost complete
closure of fissure except anterior
posterior extents
7th week (15-16mm)- distal end
closure complete
20-21 mm- proximal end closed

7. DEVELOPMENT OF IRIS
Mesenchyme on anterior
surface of lens- pupillary
membrane
2 layers of neuroectoderm
(that form edge of optic cup)
extend onto posterior surface of
pupillary membrane
3 structures- non-pigmented
epithelium, pigmented
epithlium & pupillary membrane
fuse to form – IRIS
Sphincter & dilator pupillae –
anterior epithelium
(neuroectodermal)

8. PUPILLARY MEMBRANE
Attached to edge of
pupil
As mesenchyme splits
the membrane
separates from iris but
remains attached
anteriorly
9th month- degenerates
& disappears

9. VASCULATURE
6th week -Vascular channels
arise as blind outgrowths
LPCA join peripheral vessels of
tunica vaculosa lentis- major
arterial circle
Vascular loops from LPCA &
major arterial circle – pupillary
membrane
End of 4th month- 2 layers of
vascular system of iris
Anteriorly- vessels of
iridopupillary membrane
Posteriorly -vessels of tunica
vasculosa lentis

10. COLLARETTE
Related to arteriovenous loops of pupillary
membrane
6th month- pupillary portion ofTVL regress
(central region to peripupillary region of iris)
Incomplete AV anastomosis (lesser circle) forms
at ciliary end of sphincter muscle - collarette

11. MACROSCOPIC APPEARANCE
ANTERIOR SURFACE OF IRIS
IT IS DIVIDED INTO 2 ZONES BYTHE COLLARETTE
CILIARY
ZONE
PUPILLARY
ZONE

12. CILIARY ZONE
RADIAL STREAKS
> due to underlying radial vessels
> straighten on miosis & get
wavy on mydriasis
CRYPTS
> Peripheral crypts ( near root )
> Central crypts ( near collarette )
CONTRACTION FURROWS
> prominent in outer ciliary zone
> prominent on mydriasis

13. PUPILLARY ZONE
1.6 mm wide
Between Collarette & pigmented Pupillary Ruff
Pupillary Ruff
• Represents anterior end of embryonic optic cup
• Posterior epithelial layers of iris extend forward
at the pupillary margin
• Crenations result from a forward extension of
radial folds of posterior iris surface

14. POSTERIORSURFACEOF IRIS
SCHWALBE’S CONTRACTION FOLDS
> radial furrows commencing 1mm from
pupillary border
SCHWALBE’S STRUCTURAL
FURROWS
> commencing 1.5mm from pupillary
border
CIRCULAR FURROWS
> finer than radial furrows
> more marked near the pupil

15. PUPIL
Defined as an aperture in the iris of about
(3-4)mm, which regularises the amount of light
reaching the retina.

16. EMBRYOLOGICALLY
IRIS IS DIVIDED INTO 3 LAYERS
SUPERFICIAL
MESENCHYMAL
LAYER
DEEP
MESENCHYMAL
LAYER
POSTERIOR
SURFACE

17. Ciliary border to
Collarette
Gives colour to Ciliary
portion of iris
In it lies the iris crypts,
bounded by the
trabeculae of the
Collarette
SUPERFICIAL MESENCHYMAL LAYER

18. DEEP MESENCHYMAL LAYER
Ciliary border to Pupillary edge
Superficial mesenchymal layer is
loosely attached & glides freely over
it
On mydriasis, the pupillary edge
approaches nearer to the collarette

19. POSTERIOR SURFACE
is dark brown in color & smooth in
appearance
displays radial and circular furrows

20. SPHINCTER PUPILLAE
 circular group of muscle
 contracts pupillary size
in bright light
DILATOR PUPILLAE
 radial group of muscle
 dilates pupillary size in
dim light
MUSCLES OF IRIS
2 GROUPS OF MUSCLES –

21. MICROSCOPIC STRUCTURE
ANTERIOR LIMITING LAYER
IRIS STROMA
ANTERIOR EPITHELIAL LAYER
POSTERIOR PIGMENTED EPITHELIAL LAYER

22. MICROSCOPIC STRUCTURE
ANTERIOR LIMITING LAYER
consists of melanocytes & fibroblasts
deficient in areas of crypts & very thin at
contraction furrows
definitive colour of iris depends on this layer

23. IRISSTROMA
SPHINCTER PUPILLAE
DILATOR PUPILLAE
BLOODVESSELS
PIGMENT CELLS

24. IRISSTROMA
1. SPHINCTER PUPILLAE
> 1mm broad circular band in the
pupillary part of iris
> derived from Neuro - ectoderm
> supplied by parasympathetic fibers
through the 3rd nerve
> constricts pupil
2. DILATOR PUPILLAE
> derived from Neuro - ectoderm
> extends from iris root towards pupil
> supplied by cervical sympathetics
> dilates pupil

25. 3. BLOODVESSELS
> radial vessels are derived from CIRCULUS
ARTERIORUS MAJOR
> responsible for the radial streaks
> straighten when pupil constricts & wavy when pupil
dilates
> absence of internal elastic lamina
> non - fenestrated capillary – endothelium
4. PIGMENT CELLS
 Melanocytes
 Clump cells

26. IRISSTROMA

27. BLUE IRIS
It is due to the absence of pigment in the iris stroma,
the pigment in the retinal epithelium being seen
through the translucent membrane

28. ANTERIOR EPITHELIAL LAYER
 anterior continuation of the pigment
epithelium of retina & ciliary body
 lacks in melanocytes
 Dilator pupillae arises from basal processes
of this layer

29. POSTERIOR PIGMENTED
EPITHELIAL LAYER
 anterior continuation of Non – pigmented
epithelium of Ciliary body (continuation of the
sensory retina)
 derived from Internal layer of the optic cup

30. ARTERIAL SUPPLY
Iris is mainly supplied by –
 Long posterior ciliary
arteries
 Anterior ciliary arteries
These arteries form 2 arterial
arcades –
a) Circulus Arteriosus Major
b) Circulus Arteriosus Minor

31. ARTERIAL SUPPLY

32. ARTERIAL ARCADES

33. VENOUS DRAINAGE
Iris is drained mainly by VORTEXVEINS
4 - 8 in number
Superior – temporal, Superior – nasal, Inferior –
temporal & Inferior – nasal
Superior vortexV. Superior ophthalmicV.
Inferior vortexV. Inferior ophthalmicV.

34. VENOUS DRAINAGE

35. NERVE SUPPLY
 Sensory –
derived from Ophthalmic division of
trigeminal nerve (Vth CN)
 Motor –
 Dilator pupillae Long ciliary nerve
(Cervical sympathetic chain)
 Sphincter pupillae Short ciliary nerve
(post-ganglionic parasympathetic fibers of III
CN)

36. MOTOR NERVE SUPPLY

37. CONGENITALANOMALIES OF
IRISBASED ON PIGMENTATION
HETEROCHROMIA IRIDIUM
HETEROCHROMIA IRIDIS

38. HETEROCHROMIA IRIDIUM
One iris having a different colour from the other

39. Parts of same iris, usually a sector, may differ in
color from the remainder
HETEROCHROMIA IRIDIS

40. IRIS PIGMENT ALTERATIONS
INCREASED
UVEAL & LID
PIGMENT
OCULODERMAL
MELANOCYTOSIS
INCREASED PIGMENT
& PUPILARY BORDER
CHANGES
CONGENITAL
ECTROPION
UVEAE
FOCAL &
MENTAL
RETARDATION
YES
BRUSHFIELD
SPOTS
NO
WOLFFLIN
NODULES
DIFFUS
E
(24% NORMAL POPU)

41. DIFFUSE IRIS PIGMENT
ALTERATIONS
DECREASED
SKIN/HAIR
PIGMENTATION
ALBINISM
SEIZURES &
WHITE
FORLOCKS
WAARDENBURG
KLEIN SYNDROME
SEIZURES
‘SPLASHED
PAINT’ SKIN
CHANGES
INCONTINENTIA
PIGMENTI
PTOSIS
MIOSIS
CHS

42. OCULODERMAL MELANOCYTOSIS
(NEVUS OF OTA)
Asian people
Risk of uveal, orbital and intracranial melanoma
Risk of glaucoma

43. Brushfield
spots
Wolfflin
nodules

44. WAARDENBURG KLEIN SYNDROME
Autosomal dominant
Iris heterochromia
Complete / partial / segmental
Unilateral or bilateral
Lateral displacement of medial canthi
White forlocks
Deafness

45. INCONTINENTIA PIGMENTI
X linked dominant trait
All cases – female
Hyperpigmented macules – ‘splashed paint’ app
Iris heterochromia
1/4th to 1/3rd patients – proliferative retinal
vasculopathy

46. BASED ON STRUCTURE
COLOBOMATA OF IRIS
• Greek koloboma meaning “mutilated” or
“curtailed”
ANIRIDIA
CONGENITAL ECTROPION UVEAE
PERSISTENT PUPILLARY MEMBRANE

47. TYPES OF COLOBOMATA OF IRIS
COLOBOMA
TYPICAL
COMPLETE INCOMPLETE
ATYPICAL

48. TYPICAL COLOBOMATA OF IRIS
Due to defective closure of the embryonic
fissure
Inferonasal quadrant of the eye

49. COMPLETE COLOBOMATA
extends from pupil to the optic nerve
Sector-shaped gap occupying 1/8th of the
circumference of the retina, choroid, ciliary body,
iris
corresponding indentation of the lens where
zonular fibres are missing

50. INCOMPLETE COLOBOMATA
May involve-
Iris
iris & ciliary body (more common)
iris, ciliary body & part of choroid
stops short of optic nerve

51. Colobomata of iris found in other directions
Usually incomplete
ATYPICAL COLOBOMATA OF IRIS

52. TYPES OF COLOBOMATA

53. ANIRIDIA
Rare bilateral condition
Abnormal neuroectodermal development
secondary to PAX6 gene linked to 11p13
PAX6 is adjacent toWT1
Mutation of WT1 predisposes to WILM’s tumour
Associated withWAGR syndrome
May be total or partial

54. CEU
iris stromal
atrophy
congenital
fibrosis of the
anterior iris
stroma
CONGENITALECTROPIONUVEAE
Iris pigment epithelium present at
pupillary margin & on anterior iris
stroma
Exhuberant growth of neural
ectoderm over the iris stromal
mesenchyme

55. PERSISTENT PUPILLARY MEMBRANE
Continued existence of the anterior vascular
sheath of the lens (tunica vasculosa lentis); a
fetal structure which normally disappears shortly
before birth

56. TYPES OF PPM
DUKE ELDER CLASSIFICATION
TYPE – I
membranes that are attached solely to iris

57. TYPE – II IRIDOLENTICULAR ADHESIONS
In a sub-variant of type – II
Pigmented dendritic iris stromal melanocytes (singly
& in clumps) situated on anterior lens capsule
Pigmented stars -- “chicken tracks”

58. TYPE – III
Membranes which are attached to the cornea
Typically occurs in AXENFELD – RIEGER syndrome

59. TYPE - IV
Membranes are found floating freely in
the anterior chamber

60. CONGENITAL ANOMALIES OF
PUPIL
CONGENITAL CORECTOPIA
ANISOCORIA
POLYCORIA

61. CONGENITALCORECTOPIA
Eccentric location of the pupil
Normal or malformed
Pupil may have an abnormal
shape (dyscoria) & not in line
with the lens
Marker for chromosomal or CNS
abnormalities
May be associated with
coloboma of iris

62. CONGENITAL CORECTOPIA
Ectopia lentis et pupillae
Autosomal recessive trait
eccentric location of both
the lens & pupil
eccentric together and in
line or
displaced in opposite
direction (more common)
Axial myopia

63. ANISOCORIA
Unequal sizes of pupils
Defined by difference of 0.4 mm or more
May be normal & asymptomatic
May be associated with Congenital Horner’s
Syndrome or other congenital neurological
abnormalities

64. POLYCORIA
Condition in which there
are many openings in
the iris
Local hypoplasia of the
iris stroma & pigment
epithelium
TYPES
True polycoria
multiple openings
in iris with intact
sphincter action
Pseudopolycoria
multiple openings
in iris without
sphincter action

65. CONGENITAL ANOMALES OF IRIS
ASSOCIATED WITH OTHER
ANOMALIES
OCULAR ALBINISM
CONGENITAL HORNER’S SYNDROME
COGAN – RESSE SYNDROME
AXENFELD – RIEGER SYNDROME
PETER’S ANOMALY

66. OCULAR ALBINISM
Genetic condition due to disorder of
melanosome biosynthesis
GPR143 gene mutation
Minor skin manifestations & congenital
and persistent visual impairment in
affected males
X – linked Inheritance
Males are affected
Females are carrier
Typical carrier signs
 irregular retinal hypopigmentation
 mild iris transillumination

67. OCULAR CHARACTERISTICS -
 Infantile Nystagmus
 Hypopigmentation of the Iris
 Hypopigmentation of ocular fundus
 Foveal hypoplasia
 Reduced visual acquity
 Aberrant optic pathway projections

68. CONGENITALHORNER’SSYNDROME
Defect in sympathetic innervation to the eye &
adnexal structures
Ipsilateral ptosis, miosis, enophthalmos &
anhydrosis of the face
Less than 5% of cases are truly congenital

69. CAUSES OFCHS-
Birth trauma resulting in brachial plexus injury
Thoracic & Cervical neuroblastoma
Agenesis of the Internal carotid artery
Complications from perinatal surgical procedures
Carotid artery aneurysms

70. IRIS NAEVUS ( COGAN – RESSE )
SYNDROME
Characterized by
diffuse naevus which covers the anterior iris or
iris nodules

71. AXENFELD– RIEGERSYNDROME
It is characterized by –
AXENFELD ANOMALY
Autosomal dominant trait
Posterior embryotoxon & bridges of iris tissue
crossing anterior chamber angle to insert at
Schwalbe’s line

72. RIEGER ANOMALY
It is characterized by –
Posterior embryotoxon
Iris stromal hypoplasia
Ectropion Uvea
Corectopia & full thickness iris defects

73. RIEGER SYNDROME
Dental anomalies – hypodontia & microdontia
Facial anomalies – maxillary hypoplasia, broad
nasal bridge, telecanthus & hypertelorism
Other anomalies – redundant periumbilical
skin & hypospadius
2 gene loci –
 4q25
13q14

74. PETERSANOMALY
Extremely rare but serious condition
Defective neural crest cell migration in
the 6th to 8th weeks of fetal development
( time of development of anterior
chamber )

75. It is characterized by –
Central corneal opacity of
variable density
underlying posterior stromal
defect
defect in the descement
membrane & endothelium with
or without irido-corneal or
lenticulo-corneal adhesions

76. PRIMARY IRIS CYSTS
TYPES
EPITHELIAL
CYSTS
STROMAL
CYSTS
(rare)

77. EPITHELIAL CYSTS
Lesions arise from iris epithelium
Unilateral or Bilateral
Solitary or multiple globular structures
Brown or transparent
Location may be at the pupillary border or in
the mid zone of the iris root

78. STROMAL CYSTS
Solitary & U/L
Smooth translucent anterior wall
Remain dormant for many years or
Suddenly enlarge & cause Secondary Glaucoma
& Corneal decompensation

79. CONCLUSION
Iris is an important ocular structure
It regulates the amount of light entering
the interior of the eye
It regulates the flow of aqueous from
posterior to anterior chamber
It keeps the interior of the eye dark
Knowledge of its structural anatomy &
embryology is very important for diagnosis
& evaluation of not only various congenital
& acquired anomalies of eye but also of
other systems as it is associated with
various syndromes