• Coloboma (pl:colobomata) is derived from the Greek word
koloboma,meaning mutilated or curtailed.
• used to describe ocular defects of the eyelids, lens, cornea,
iris, ciliary body, zonules, choroid, retina and optic nerve.
• typically located in the inferonasal quadrant of the involved
• often associated with microphthalmia.
• Incidence rates: 0.7 per 10,000
• The prevalence of coloboma
∞ among blind adults :0.6–1.9%
∞ among children :3.2–11.2%.
• highest prevalence in visually-impaired Japanese school
children - 11.2%.
• may be sporadic or inherited
A) Without associated systemic abnormality
• Autosomal dominant transmission
– Macular colobomas
• Autosomal recessive transmission
B) With associated systemic abnormalities
• Autosomal dominant transmission
– microphthalmia +coloboma with carcinomas, jaw cysts,
abnormalities of the ribs and spine and hip, and mental
– arachnodactyly, a marfanoid aspect + uveal coloboma. due to
deficient gene on chromosome 5.
• Autosomal recessive transmission
– Meckel-Gruber syndrome
– Sjogren-Larson .
• X chromosome
– Lenz syndrome
– Aicardi syndrome
• Transmission unknown
– CHARGE syndrome
• Chromosomal aberrations
– triploidy , trisomies 13, 18 and 22, duplications 4q +, 7q +, 9p
+, 9p + q +, 13q +, 14q +, 22q +, the deletions 2p22, 4p-, 4del
(q12q12.1) (P15q23.1), and an XY , XYY anomaly . inversions Inv
C. environmental causes and intrauterine insults
• thalidomide A
• Intrauterine vitamin A deficiency,anticonvulsants diphenyl
hydantoin and carbamazapine
• fetal alcohol syndrome
• due to failure of the fetal /choroidal fissure to close
during 5th - 7th week of fetal life, at 7–14 mm stage ,the
period between the invagination of the optic vesicle and
the closure of the fetal fissure.
• Coloboma eyelid defective eyelid development/ globe.
• Coloboma cornea, iris, ciliary body, choroid, retina and
ON failed or incomplete closure of embryonic fissure
on day 33 of gestation
• Coloboma of the lens is a misnomer & is due to
defective or absent development of the zonules in any
segment lack of tension on the lens capsule
contraction and notching of that region.
• named so, because it is the most frequent.
• occurs in the inferonasal quadrant,
• caused by defective closure of the fetal fissure.
• may affect any part of the globe traversed by the fissure from iris
to the optic nerve.
• located anywhere other than inferonasal quadrant of the globe
• the embryologic basis unclear, several theories suggested.
• “rotation” of the fetal fissure or a result of an intrauterine
• Atypical ciliary body coloboma : caused by persistence of
mesodermal tissue from the embryonic vascular system blocking
the forward growth of the neuroectoderm
• Optic nerve pits on the temporal aspect of the disc
• Eyelids develop from surface mesoderm as mesoblastic folds, at
4–5 weeks from above and below meet at palpebral fissure at
the 32-mm stage, Fusion :inner canthus regionlaterally
completes at 37–45 mm stage.
• Structures of the lid margin (Meibomian glands, Moll and Zeiss,
cilia, muscle fibers,tarsal plates) differentiate while the lids are
• by the end of the 5th month :Epithelial adhesion of the lids begins
to break down.
CAUSES OF LID COLOBOMA
• Failure of adhesion of the lid folds by maternal virus infection
• a deficiency in migration
• excessive death of neural crest cells
• due to 2⁰ to globe abnormalities(controversy)
• partial thickness
• full thickness
• quadrilateral or triangular gap, broadest at the lid margin;
• can affect orbital margin & adnexa localized absence of the
eyebrow,anomalous wedge of scalp hair extending toward
coloboma,Lacrimal drainage anomalies
• Upper lid colobomata
• more common
• generally isolated with the exception of Goldenhar syndrome,
• usually full thickness & occur at the junction of the inner and
middle thirds with normal adjacent lid margins
• lower lid colobomata
• usually seen with mandibulofacial dysostosis (TreacherCollins)
• mostly at the junction of the middle and lateral thirds, usually
partial thickness, only involving the anterior lamella
History & examination
• Perinatal and pregnancy history
• Family history of congenital eyelid colobomas /other
congenital anomalies (eg, cleft lip/palate)
• History of other birth defects
• Pediatric review of systems
• History of progressive corneal problems
complete ophthalmic assessment, under GA
– Dermoid tumors
• Eyebrows - Defects
• Lacrimal system -Obstruction proximal to the lacrimal sac
– Malformation of the caruncle
– Exposure keratopathy
– Cataract (anterior polar)
- Epibulbar dermoid tumor
• Iris – Coloboma
• Choroid – Coloboma
• CT scan of the orbits and the skull in Treacher Collins
• Treatment of eyelid defects
• depends on the extent of involvement , corneal
• conservative Rx
• Initial therapy
• topical lubricants,e/o,BCL,moisture chambers
bandages,bed time patching
• Surgical repair
– corneal decompensation by dehydration or trichiasis.
– 4 cosmesis
• complication :in young children occlusion amblyopia
during the healing phase.
Small defects well managed with lubricants
• repair delayed until adulthooddirect closure by
apposition of the edges after they are mobilized and
freshened with sharp incisions & precise
anastamosislid margin approximation in 2 layers
,tarsus & skin.
• lateral cantholysis to minimise sutural tension.
moderate sized coloboma(70% of the lid)
• fashion a pentagonal lid defect to facilitate
reapproximation a lateral cantholysis
• immediate closure to protect cornea2 staged
• procedure employed depends on the lid involved
• Lower lid: modified Hughes procedure:upper lid tarso-
conjunctival flap (for tarsus layer) with retroauricular
skin flap (for skin layer)
• Upper lid: modified Cutler-Beard procedure : lower lid
tarso-conjunctival flap (for tarsus layer) with
retroauricular skin flap (for skin layer).
• Alternate techniques for upper lid or the lower lid:
– a semicircular flap from the lateral canthal area (Tenzel or
modified Tenzel )
– full-thickness lid rotational flap.
• Congenital amniotic band syndrome
• Eyelid trauma
• Total /Partial
• Complete /Bridge/Incomplete
• full thickness defect
• involves both the pigment epithelium and the iris
• may be :
o total, extending to iris root “keyhole pupil”
o partial, involving only pupillary margin slightly oval
Small strands of mesodermal tissue bridge the
coloboma polycoria/may extend to the lens as a
persistent pupillary membrane
• usually partial thickness, involving either the
pigment epithelium or the iris stroma.
• usually wedge-shaped
• best demonstrated by iris transillumination.
• associated with Heterochromia iridis
• usually no visual defect,
• indicated only for cosmesis
• cosmetic contact lens :
– resembles normal iris & can be optically corrective also.
– designed to match the fellow eye in appearance.
– useful for microcornea + coloboma and microphthalmia
• undertaken as part of cataract extraction /PK at any age.
• Post implantation, coloboma is repaired with
nonabsorbable sutures/with artificial iris
• PCIOL >sulcus placement >ACIOL :IOL preferred
• haptics are placed 90⁰ from the defect ,to stabilize
• provide a stable platform for ACIOL.
• lens implantation and may prevent Synechiae ,2⁰ ACG.
• in cataract and microphthalmia postop uveal effusion,
RD , intraocular hemorrhage, malignant glaucoma.
• previous or simultaneous sclerotomy or sclerectomy can
b done to reduce the incidence of postoperative uveal
• not a true coloboma
• secondary to zonular & ciliary body defects.
• No lens tissue is missing but absence of zonular fibers
from area of colobomatous ciliary body lack of tension
on the lens capsule there Notched equator/ Flattening
of the inferior lens /superior lens subluxation.
• usually u/l & infero nasal
• dilated eye examinationmanifest refractiontreated
with corrective lenses.
• If severe & not corrected lens extraction IOL to
prevent amblyopia taking care of zonular abnormalities.
CILIARY BODY COLOBOMA
• most common congenital defect in the ciliary
• may be visible through the overlying iris
coloboma as white lesions with varying degrees
of pigmentation at the margins related to
hyperplasia of pigment epithelial cells
• no specific treatment for ciliary body colobomata
• choroidal /retinochoroidal coloboma
– macular coloboma
– optic nerve coloboma
– Uveal coloboma
• If the retina is involved, glial tissue with no
underlying RPE or choroidarea of whitening
with pigment deposition at the junction of the
coloboma and normal retina.
• If the optic nerve is involvedrange of
appearance from physiologic cupping to
extensive retinal involvement
• infrequent, 0.5 to 2.2 cases per 10,000 births
• Histological findings :
– absence of RPE beneath but hyperplastic at the edge of defect.
– The overlying retina is hypoplastic ,gliotic, and has rosettes &
if recognizable, the retinal layers are reversed,with rods and
cones facing inward and RNFL adjacent to sclera.
– Underlying choroid is either hypoplastic or absent
– thin sclera with cystic spaces filled with glial proliferation
• primarily genetic in origin.
• may go from front to back (continuous) / as “skip
• iris coloboma (front of the fissure), a chorio-retinal
coloboma (back of the fissure), or combination
Ida Manns classification(1937)
2-superior border of OD
3-seperated from OD by n/l 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
• depends on amount and location of missing tissue.
– retino choroidal coloboma in early life as leukocoria
– coloboma of macula and optic nerve reduced vision.
– coloboma of any part of retina absolute scotomata
– coloboma of iris & lens asymptomatic ,except glare .
• RD in retinochoroidal choloboma 23–42%, common in males <
• retinal break have higher rate, holes are atrophic, without
operculae, and hidden near the edge of the coloboma or under a
hemorrhage, and are difficult to localize, due to low contrast in
colobomatous area, nystagmus,ectatic sclera, absence of choroid,
and thinned retina
• Near the margin of the coloboma, the retina splits into
two layers at the level of INL/OPLThe inner layer b
comes intercalary membrane on to the coloboma, while
the outer layer becomes disorganized, and fuses RPE
• The choroid is terminated as a distinct pigmented layer
peripheral to this point of reversal.
• The junction where this reversal occurs is a locus
minoris resistentiae. The intercalary membrane
• progressively becomes thinner as it is traced centrally.
• Breaks can occur at the junction and in the intercalary
• usually bilateral, symmetrical, circumscribed and
excavated defects that involve both the choroid and
• classified into three main types:
– pigmented macular coloboma,
– nonpigmented macular coloboma,
– macular coloboma associated with abn/l
• U/l sensory strabismus,with organic amblyopia.
• B/l in infancy with poor visual function and
• toxoplasmosis,Leber’s congenital amaurosis
optic disc coloboma
• Isolated disc coloboma presents as large,white,
sharply delineated, bowl-shaped excavation of
disc, 2–8 D in depth with a rim of neural tissue
preserved superiorly .
• classified into six types, to help in predicting the
degree of visual impairment in optic disc
colobomata, particularly in infants and young
• v/a best in type 1,2,3.
– morning glory disc anomaly,
– congenital forebrain anomalies.
– Basal encephalocoeles/herniations of brain tissue
– craniofacial :cleft lip and palate, agenesis of the corpus
colosum, defects in the sella turcica, endocrine
• Optic Nerve coloboma
– Morning glory
– Congenital optic pits
– Optic nerve staphylomata
• Retinochoroidal colobomata
– inflammatory lesions
– causes of leukocoria.
• Prophylactic laser treatment atleast in 3-4 rows
posteriorly along the edge of the coloboma and
• If adequate chorioretinal adhesion can be achieved
around the coloboma, laser of the papillomacular
bundle and OD not done.
• complication :creates RNFL defects in eyes with already
compromised visual fields so, diode laser is better than
• If requiring surgery, initially laser photocoagulation.
Vitrectomy and air-fluid exchange with a buckle
• retinal detachment + choroidal coloboma vitrectomy
with either long-acting gas or oil tamponade is done .
COMPLICATIONS OF COLOBOMA
• Chorio retinal colobomas retinal detachment
• Dislocations associated with lens colobomes
• A coloboma and retinoblastoma in 13q- deletion .
• Subretinal neovascularizations
• corneal complications ( ulcerations )in upper
• effective examination under general anesthesia.
• S/L evaluation to find AS manifestations.
• Choroidal, retinal, ON direct and indirect ophthalmoscopy.
• Accurate refraction
• CT/MRI microphthalmia and associated CNS d/s.
• Axial length by high resolution ultrasonography.
• Older patients VF assessment
• severe microphthalmia scleral shells With periodic refitting,
• gradual expansion of the fornices with ring-type prostheses.
• Orbital growth induced by spherical intraorbital tissue
expanders/intraorbital balloon devices/dermis graft to
promote the development of symmetrical ocular appearance
• safety glasses & goggles for sports in children
• trial of part-time occlusion
• Strabismus & nystagmus with compensatory face turn is
• Genetic counselling wherever necessary