This document discusses choroidal coloboma, beginning with definitions and epidemiology. It describes the embryonic development of the eye and how failure of fusion of the embryonic fissure can result in coloboma. Types of coloboma are classified based on location and presence of other anomalies. Complications like retinal detachment are discussed. Management of cataracts and other ocular issues in the context of coloboma are covered. The prognosis depends on factors like presence of microphthalmos, corneal diameter, and type and timing of surgery.

1. Choroidal coloboma
Presenter :Dr. Rahul
Moderator: Dr. Archis

2. Coloboma
Coloboma
(kolobomos :Greek for
mutilation)
Indicates “a condition
where a portion of the
structure of the eye is
lacking”

3. Epidemiology
Incidence is 5 per 1,00,000 newborns
Prevalence is 1 in 10,000
60% are bilateral
Molecular genetics
 deletion in gene which maps to chromosome 7q26.
 a mutation in the PAX6 g
 # Warburg M
J Med Genet. 1993 Aug;30(8):664-9

4. Types
According to site of
genesis
 Typical
 Atypical
As an isolated
anomaly with or
without
microophthalmia
Unilateral or Bilateral

5. Phenotypic classification
It may help the clinician to give a systematic
description of the anomalies
Two major classes
Total
Partial

6. Aetiological classification
• The aetiological classification consists of
three classes:
• Genetic
• Prenatally acquired
• Associations
• The aetiological classification can be
applied to other congenital birth defects
and improves counselling of families #
# Warburg M
J Med Genet. 1993 Aug;30(8):664-9
Classification of microphthalmos and coloboma

7. Embryonic Origin
The eye is derived
from the neural tube
(neuroectoderm),
from which arise the
retina proper
The neural crest cells
produce the
corneoscleral and
uveal tunics
 From the surface
ectoderm, lens.

8. The earliest stage of
eye development is the
formation of the
paired optic
vesicles on either side
of the forebrain.

9. These growing
diverticula expand
laterally into the
mesoderm of the head
and develop a stalk-
like connection to the
main portion of the
rudimentary central
nervous system

10. In humans, this process begins at about 22 days of
development
 The vesicles continue to grow, their connection to
the brain becomes progressively narrower and more
stalk-like.
This stalks will eventually become the rudiments of
the optic nerves.

11. There is a seam at the
bottom of each stalk,
where blood vessels
originally run.
This seam is known as
the optic fissure or
choroidal fissure or
embryonic fissure.

12. The closure starts roughly in the middle of the
developing eye, and runs in both directions.
This process is start at five week & finished by the
seventh week of gestation.
If, for some reason, the closure does not happen, a
uveal coloboma is formed

13. Depending on
where the closure
did not happen, the
baby can have
 an iris coloboma
(front of the fissure)
 a chorio-retinal
coloboma (back of
the fissure)
 any combination of
these.

14. Uveal coloboma can
affect one eye
(unilateral) or both
eyes (bilateral)

15. A uveal coloboma may go from front to back
continuous or have “skip lesions”.
The fact that the seam runs at the bottom of the stalk
is the reason why uveal coloboma is always located in
the lower inside corner of the eye.

16. Pathophysiology
Fusion or closure of
the fissure begins in its
central portion in the
11-mm embryo and
proceeds anteriorly
and posteriorly.
Closure of the fissure
is complete by the
sixth week (13-mm
stage).

17. Pathophysiology
In the normal eye, optic fissure closes 33 to 40
days after conception.
Failure of the embryonic fissure to close along the inferonasal
aspect of the optic cup and stalk
That causes Retinal neurosensory elements and RPE precursors
fail to become confluent.
Due to which underlying choroid fails to differentiate
That results in bridge of bare sclera or a cyst formation

18. Pathophysiology
Anteriorly
defects in the neuroectodermally derived iris pigment
epithelium produce iris coloboma
Posteriorly
The entire optic nerve head may be involved in a
colobomatous malformation

19. Typical/atypical
Colobomas are called typical if they are located
inferonasally in the region of the fissure
Typical colobomas can involve the iris, ciliary body,
choroid, or any of the three, and also may involve the
optic nerve
Atypical colobomas are not related to closure of the fissure

20. Multi-system involvement
A single-gene disorder
with multisystem
involvement
Aicardi's syndrome
Lenz microphthalmia
syndrome
Meckel's syndrome
Warburg's syndrome

21. Aicardi's syndrome
Absence of corpus
callousm
Consist of triad -
Agenesis of the corpus
callosum
 infantile spasms.
morning glory
syndrome

22. Multisystem disorder
without known genetic
cause
CHARGE association of
anomalies
 colobomatous
Microphthalmos
 heart defects
 choanal atresia
 retarded growth
 genital anomalies
 ear anomalies or deafness
(At least three of the
features are necessary
for the diagnosis)

23. Iris coloboma
Total
if they involve a whole sector
of the iris up to the ciliary
body“keyhole” defect
Partial
if they do not involve a
whole sector of the iris
may appear as a notch at the
pupillary margin

24. Histological
Complete coloboma
involves the whole thickness of the iris
Incomplete coloboma
involves either the pigment epithelium or the stroma
Bridge coloboma
mesectodermal tissue forms a pupillary membrane that
stretches across the defect

25. Lens coloboma
Coloboma of the lens is not a true coloboma.
No lens tissue is missing
An absence of zonular fibers from an underlying
colobomatous ciliary body
Results in a lack of tension on the lens capsule in
that region
Notched equator/ Flattening of the inferior lens

26. Lens notches can
occur wherever
zonules are absent or
deficient
 zonular rupture
during early surgery

27. Ida Manns classification(1937)Ida Manns classification(1937)
1-above the optic disc
2-superior border of
optic disc
3-seperated from the
optic disc by normal
narrow area of retina
4-inferior crescent
below the disc
5- isolated gap in the
line of fissure
6-area of pigmentary
disturbance
7-extreme peripheral
coloboma

28. 1)area of pigmentary
disturbance
2) isolated gap in the
line of fissure
3) above the optic disc

29. Retinal detachment in colobomaRetinal detachment in coloboma
40% develop RD , accounts for 0.5% of RD in young.
May or may not be due to coloboma
Vitreous traction cause breaks outside coloboma

30. RD due to coloboma is break along edge of coloboma
It is difficult to visualise breaks because they are under
edge or close to haemorrhage

31. Treatment modalitiesTreatment modalities
 Cryo to anterior margin and photocoagulation to
posterior margin
 Radial buckles (Patnaik et al,1961)-may extend to disc if
large.35-57% success rate

32. Management of RD with ColobomaManagement of RD with Coloboma
Prophylactic laser delimitation of the coloboma margins
If RD is due to peripheral coloboma-conventional scleral
buckling surgery &Vitrectomy with
endophotocoagualation with silicon oil injection

33. Management of RD with ColobomaManagement of RD with Coloboma
Lensectomy may be required in cases of difficulty in
visualizing inferior retina
Breaks usually identified
AFE easily done as sclera is concave
Prolonged inferior tamponade needed-silicon oil gas.

35. SRNVM in retinochoroidal coloboma
Pathology-absence of choroid with breach in bruch’s
membrane leading to vessels entering sub-retinal space.
Also RPE abnormalities stimulate budding of
choriocapillaris endothelial cells.
Laser photocoagulation is advised modality of treatment.

36. Cataract in colobomatous eyes
Clinically significant cataract develops at a
younger age compaired with age-related nuclear
sclerotic cataract.
Cataract more likely to be denser.
Cuniform opacities are more likely to occur
earlier.
Increased no. of subluxated lens due to
associated zonuler deficiency
Michael L. Nordlund, Alan Sugar, Sayoko E.
Moroi,
J Cataract Refract Surg 2000; 26:1035-1040

37. Microophthalmos in colobomatous
eyes
Prevalence 21 per 100,000
82% at least >+7.00D of hypermetropia
Coloboma is the second MC association after cataract
(22% v/s 44%)
Microophthalmos with coloboma may or may not be
associated with microcornea
Mark J etal
Aetiology of severe visual impairment and
blindness in Microophthalmia
BJO 1994(78);332-334

38. Microophthalmos in colobomatous
eyes
A person with coloboma with microophthalmos
with microcornea has a poorer visual prognosis
than a person with coloboma with
microophthalmos without microcornea
Further a newborn with a corneal diameter<5mm
has a very poor prognosis
Mark J etal
 Aetiology of severe visual impairment
 and blindness in Microophthalmia
 BJO 1994(78);332-334

40. Microcornea in colobomatous eyes
The term microcornea implies
a corneal diameter of less than 10 mm.
 It thought to occur secondary to an arrest in corneal
growth after the fifth month of fetal development.
It often occurs with ocular abnormalities such as
colobomata and microophthalmos may be present
Microcornea accompanies anterior microphthalmos,
with crowding of the anterior segment structures

41. Management
Systemic evaluation
Ocular examination.
Investigations
Axial length
Keratometry
IOL Master
USG
UBM

42. Management
Clinically significant cataract develops at a younger age
If a coloboma involves the macula Axial length will be
varied so earlier refraction will be important or Axial
length may be obtained by locating the preferred fixation
point
Coloboma with microophthalmos with microcornea –
ECCE not a viable option
 The crystalline lens has been reported to be of normal or
slightly larger than normal size
#

43. Management
The lens:eye volume ratio is greater (10 to 32 percent) in
these eyes compared with emmetropic eyes (3 to 4
percent)
So Phaco-emulsification / manual phaco (SICS) is a
viable option
Phaco-emulsification—e.g. Slit Nucleotomy, Wooden
boot, Petalloid etc.
Manual phaco (SICS) —e.g. Sandwich technique,
Quarters technique, Phacotrisection etc.
 Michael L. Nordlund, Alan Sugar, Sayoko E. Moroi,
 J Cataract Refract Surg 2000; 26:1035-
#

44. Management
Minimal mydriasis or reactive miosis should be
anticipated
Iris retractors / multiple sphicterotomies
CCC run-off or tear can occur
Recommendations for CCC
Eccentric capsulorhexis
Increased magnification with dye assistance
Oblique illumination
Two stage CCC
Good chamber maintainence with viscoelastic
Nucleus sculpting / Nucleus cracking at opposite meridian + PCIOL@90°
to tear
Endothelial losses
Shell technique can be used
Michael L. Nordlund, Alan Sugar, Sayoko E. Moroi,
 J Cataract Refract Surg 2000; 26:1035-
#

46. Management
 Anterior vitrectomy
Vitreous loss –
Prolapse through PC rent
Prolapse through colobomatous area without PC rent
 Optimal centeration of the optic with the ectopic pupil to avoid
post-op mono-ocular diplopia
Puppiloplasty may be required
 Avoid silicon material IOLs
As future VR surgery may entail the use of silicon oil
# Michael L. Nordlund etal
Phacoemulsification and intraocular lens placement in
eyes with cataract and congenital coloboma: visual
acuity and complications
J Cataract Refract Surg 2000; 26:1035-1040

47. Prognosis
The prognosis for vision depended on the phenotype of
the better eye
 Microphthalmos with cyst has the worst prognosis
 Coloboma with microcornea and microphthalmos a poor
prognosis
 Coloboma with only microcornea has an intermediate prognosis
 Simple coloboma has the best prognosis
A corneal diameter <6 mm had a poor visual prognosis
whereas a corneal diameter >10 mm had a good prognosis
Time of surgery
Type of surgery
Hornby SJ, etal
Ophthalmology. 2000 Mar;107(3):511-20
Visual acuity in children with coloboma
Michael L. Nordlund, Alan Sugar,
Sayoko E. Moroi,
J Cataract Refract Surg 2000; 26:1035-
1040