3. SIZE, SHAPE AND RELATIONS
OF BONY ORBIT
The two bony orbits are quadrangular
truncated pyramids
These are situated between the anterior
cranial fossa above and the maxillary
sinuses below.
Each orbit is formed by seven bones-
frontal, ethmoid, lacrimal, palatine, maxilla,
zygomatic and sphenoid.
4.
5. The medial walls of the two orbits are
parallel to each other.
They are in contact with the ethmoid and
sphenoid sinuses, which separate the
orbits from the nasal cavities.
The lateral wall of each orbit lies at an
angle of 45 degree to the medial wall.
The lateral walls of the two orbits are at
90° to each other.
6.
7. The lateral wall separates the orbit from
the middle cranial fossa posteriorly and
the muscular temporal fossa anteriorly
The depth of the orbit is 42 mm along the
medial wall and 50 mm along the lateral
wall.
The base of the orbit is 40 mm in width
and 35 mm in height.
8. The intra-orbital width i.e. the distance
between the medial margins of the right
and left orbits is 25 mm.
The extraorbital width, i.e. the distance
between the right and left lateral orbital
margins is 100 mm
9. The relationship between the height and
width of the orbit is expressed by the
orbital index.
Orbital index = (Height/Width) x 100.
This index shows racial variation.
Races having an orbital index greater than
89 are termed megasenes (e.g. orientals).
10. Mesosenes (e.g. Caucasians) have an
orbital index between 83 and 89.
Blacks with an index of less than 83 are
termed microsenes.
The volume of each orbit is about 29 ml.
The ratio between the volume of the orbit
and of the eyeball is 4.5:1
11.
12. WALLS OF THE ORBIT
The bony orbit has four walls: medial wall,
lateral wall, roof and floor.
These four walls meet at the superior
internal, superior external, inferior internal
and inferior external angles of the orbit.
13.
14. Medial Wall
It is quadrilateral In shape
It is formed (from front to back) by the-
Frontal process of the maxilla
Lacrimal bone
Orbital plate of the ethmoid bone
Body of the sphenoid bone
15.
16.
17. The anterior part of the medial wall bears
the lacrimal sac fossa, which is continuous
inferiorly with the nasolacrimal canal
The lacrimal fossa is bounded anteriorly
by the anterior lacrimal crest of the
maxillary bone and posteriorly by the
posterior lacrimal crest of the lacrimal
bone.
18. Medial to the lacrimal fossa lie the anterior
ethmoidal sinuses in the upper part and
middle meatus of the nose in the lower
part
Lacrimal sac along with its fascia lies in
the lacrimal fossa.
19. Just behind the posterior lacrimal crest
following structures have their attachment-
Horner's muscle (lacrimal fibres of the
orbicularis)
Septum orbitale
Check ligament of the medial rectus
muscle
20. Relations of the medial wall-
Medial to the medial wall (towards the
nose) lie anterior ethmoidal air sinuses,
middle meatus of nose, middle and
posterior ethmoidal sinuses and
sphenoidal air sinus.
21.
22. The orbital surface of the medial wall is
related to superior oblique muscle in the
upper part near the roof and medial rectus
muscle in the middle part.
In between these two muscles lie the
anterior ethmoidal nerve, posterior
ethmoidal nerve, infratrochlear nerve and
terminal branch of the ophthalmic artery.
23. Clinical applications of the medial wall-
The medial orbital wall is the thinnest wall
of the orbit.
This accounts for ethmoiditis being the
commonest cause of orbital cellulitis,
especially in children.
24. The medial wall is frequently eroded by
chronic inflammatory lesions, cysts and
neoplasms that originate in the adjacent
air sinuses.
It is easily fractured during injuries as well
as during orbitotomy operations.
25. During surgery along this wall,
haemorrhage is most troublesome due to
injury to ethmoidal vessels.
In addition, the medial palpebral, frontal
and dorsal nasal arteries pass forward
near the medial wall.
The medial wall can be easily visualised
with routine PA radiographs of the orbit.
26. Inferior orbital wall (floor)
It is triangular in shape.
It is the shortest of all the walls.
It is formed by three bones:
Orbital surface of the maxillary bone
medially
Orbital surface of the zygomatic bone
laterally
Palatine bone posteriorly
27.
28. The posterior part of the floor of the orbit is
separated from the lateral wall by the
inferior orbital fissure.
This fissure is continuous anteriorly with
the infraorbital groove which extends
anteriorly as a canal.
29.
30. The canal opens at the infraorbital
foramen located Just below the infraorbital
rim
The foramen transmits the infraorbital
nerve, the infraorbital artery and the
infraorbital vein (which connects the
inferior ophthalmic vein to the facial vein)
31. Relations of the inferior wall-
Below it is related to maxillary air sinus
and palatine air cells.
Above it is related to inferior rectus
muscle, inferior oblique muscle and nerve
to inferior oblique.
32.
33. Clinical applications of the floor-
The orbital floor being quite thin is
commonly involved in 'blow-out fractures'
and is easily invaded by tumours of the
maxillary antrum.
The floor of the orbit is best visualised with
standard posteroanterior radiographs.
34. The orbital floor can be approached by
inferior orbitotomy (antral approach)
easily.
However, the utility of this approach is
limited as only a small proportion of
tumours are found in this area.
35. Lateral wall
It is triangular in shape
It is formed-
Anteriorly by the zygomatic bone
Posteriorly by the greater wing of the
sphenoid bone
36.
37. On the posterior part of the lateral wall
there is a small bony projection (spina recti
lateralis) which gives origin to a part of the
lateral rectus muscle.
38. More anteriorly, the wall is marked by the
zygomatic groove and foramina (which are
traversed by the zygomatic nerve and
vessels)
On the anterior part of the wall there is a
projection, the lateral orbital tubercle of
Whitnall.
39. It gives attachment to the check ligament
of the lateral rectus muscle, and to the
suspensory ligament of the eyeball.
The lateral wall posteriorly is separated
from the roof by the superior orbital fissure
and from the floor by the inferior orbital
fissure
40. Relations of the lateral wall-
Laterally, the lateral wall separates the
orbit from temporal fossa anteriorly and
from the middle cranial fossa posteriorly .
Medially, i.e. its orbital surface is related to
lateral rectus, lacrimal nerve and vessels,
zygomatic nerve and the communication
between zygomatic and lacrimal nerves.
41. Clinical applications of lateral wall-
The lateral wall of the orbit protects only
the posterior half of the eyeball.
The anterior half of globe is not covered by
bone on the lateral side.
Hence palpation of retrobulbar tumours is
easier from the lateral rather than from the
nasal side of the eyeball.
42.
43. Because of its advantageous anatomical
position a lateral orbital surgical approach
is popular.
Further, the lateral wall is almost devoid of
foramina, so its anterior portion can be
broached without serious haemorrhage
(zygomatic-temporal vessels usually do
not pose a problem).
44. However, the lateral rim of the orbit, which
is the forward extension of the lateral wall,
is the strongest portion of the orbit and
needs to be sawed open in lateral
orbitotomy.
45. Once this bone flap has been turned, the
surgeon has direct access to the
superolateral, inferolateral and retrobulbar
quadrants of the orbit.
Since these quadrants are the common
sites of orbital tumours, the surgical
anatomy of this area is important.
46. Roof
It is triangular in shape
It is formed mainly by the orbital plate of
the frontal bone.
Behind this, it is formed by the lesser wing
of sphenoid.
The anterolateral part of the roof has a
depression called the fossa for the lacrimal
gland.
47.
48. It is usually quite smooth but may be pitted
by the attachments of the suspensory
ligament of the lacrimal gland.
The fovea for the pulley of the superior
oblique (trochlear fossa) is a small
depression situated close to the orbital
margin, at the junction of the roof and the
medial wall.
49.
50. Relations of the roof-
Above the roof is related to the frontal
lobe of cerebrum and meninges
Below the roof are periorbita, frontal
nerve, levator palpebrae superioris.
superior rectus, superior oblique,
trochlear nerve and lacrimal gland
51. At the junction of the roof and the medial
wall are the anterior and posterior
ethmoidal canals.
At the junction of roof with lateral wall is a
gap posteriorly, the superior orbital fissure.
52. Clinical applications of roof-
The superior wall is rather thin throughout
its whole extent and the periorbita easily
peels away from its undersurface.
A sharp object like walking stick or
umbrella, introduced into the orbit through
the upper lid penetrates the roof and may
damage the frontal lobe.
53. On the cranial side, the dura can be lifted
almost easily.
As the roof is perforated neither by major
nerves nor by blood vessels, it can be
easily nibbled away in transfrontal
orbitotomy.
54. BASE OF ORBIT
The anterior open end of the orbit is
referred to as base.
It is bounded by the orbital margins
The margins are formed by a ring of
compact bone.
It gives attachment to the septum orbitale
The orbital margin can be described under
four parts:-
55. Superior orbital margin-
It is formed entirely by the orbital arch of
the frontal bone.
Its lateral two-thirds is sharp and the
medial one-third is rounded.
Junction of the two parts is the highest
point of the orbital arch and here lies the
supraorbital notch
56. Which transmits the supraorbital nerve
and artery.
About 10 mm medial to the supraorbital
notch is the supratrochlear groove
Which transmits supratrochlear nerve and
artery.
57. Lateral orbital margin-
It is the strongest and is formed by
zygomatic process of the frontal bone and
the zygomatic bone.
It does not reach as far anterior as the
medial margin and thus anterior half of the
globe is not protected by the bone laterally
58. Inferior orbital margin-
It is formed by the zygomatic bone laterally
and maxilla medially, almost in equal
proportion.
It is slightly raised than the floor.
Medially it becomes continuous with the
anterior lacrimal crest.
59. The infraorbital foramen transmitting
infraorbital nerves and vessels is situated
4-5 mm below the orbital margin in line
with the supraorbital foramen.
60. Medial orbital margin-
Below it is formed by the anterior lacrimal
crest of the frontal process of maxilla and
above by the frontal bone.
Its upper part becomes continuous with
the posterior lacrimal crest.
61.
62.
63. APEX OF ORBIT
Orbital apex is the posterior end of the
orbit.
Here the four orbital walls converge.
The apex has two orifices: the optic canal
and the superior orbital fissure which are
situated in the sphenoid bone (where the
body, greater wing and lesser wing meet
each other)
64. Optic canal-
It connects the orbit to the middle cranial
fossa.
It transmits the optic nerve (surrounded by
meninges) and the ophthalmic artery.
65. Its average length is 6-11 mm (lateral wall
is shortest and medial wall is longest).
Tumours such as optic nerve glioma and
meningioma may lead to unilateral
enlargement of the optic canal, which may
be detected on X-ray films.
66. Superior orbital fissure-
It is a comma shaped aperture in the
orbital cavity.
It is bounded by lesser and greater wing of
the sphenoid.
It is situated lateral to the optic foramen at
the orbital apex.
The fissure is divided into upper, middle
and lower parts by the common tendinous
ring (for origin of the recti).
67. The structures passing through the upper
and lateral part are the lacrimal and frontal
nerves (branches of ophthalmic division of
Vth nerve),trochlear nerve, superior
ophthalmic vein and recurrent branch of
the ophthalmic artery.
68. The middle part of the fissure (within
tendinous ring) transmits the superior and
inferior divisions of the oculomotor nerve,
the nasociliary branch of the ophthalmic
division of the trigeminal nerve and the
abducent nerve.
The lower and medial part of the fissure
transmit the inferior ophthalmic vein
69.
70. PERIORBITA
The periosteum lining the surface of the
orbital bones is called the periorbita.
Generally it is loosely adherent to bone.
However, it is firmly adherent at the orbital
margin, superior and inferior orbital
fissures, the optic canal, the lacrimal fossa
and at the sutures.
71. At the orbital margin periorbita is thickened
to form the arcus marginale to which the
septum orbitale is attached.
At the posterior lacrimal crest the
periorbita splits into two layers which
reunite at the anterior lacrimal crest.
72. These two layers enclose the lacrimal sac
(in the form of lacrimal fascia).
At the apex of orbit, the periorbita is
thickened to form the common tendinous
ring of Zinn.
73. ORBITAL FASCIA
It is a complex interwoven thin connective
tissue membrane joining the various
intraorbital contents.
It can be described under the heads of
fascia bulbi, muscular sheaths,
intermuscular septa, membranous
expansions of the extraocular muscles,
and ligament of Lockwood.
74.
75. Fascia bulbi-
Fascia bulbi, or Tenon's capsule, envelops
the globe from the limbus to the optic disc
Its inner surface is well defined and lies in
close contact with sclera to which it is
connected by fine trabeculae.
76.
77. Globe and the capsule move together in
the surrounding fat.
The outer surface of the fascia bulbi lies in
contact with orbital fat posteriorly and with
subconjunctival tissue anteriorly with
which it merges near the limbus.
78. Tenon's capsule is separated from the
sclera by episcleral space (Tenon's
space). which can be readily injected.
The lower part of the fascia bulbi is
thickened and takes part in the formation
of a sling or hammock on which the globe
rests (suspensory ligament of Lockwood).
79. Around the distal end of optic nerve the
fascia is fused with the dural sheath of the
optic nerve.
Fascia bulbi is pierced posteriorly by the
optic nerve, ciliary nerves and vessels, just
behind the equator by venae vorticosae,
and anteriorly by six extraocular muscles;
where it becomes continuous with the
fascial sheaths of these muscles.
80. Fascial sheaths of extraocular muscles-
At the points where the fascia bulbi is
pierced by an extraocular muscle it sends
a tubular reflection, which clothes the
muscles like a glove.
81. Fascial expansions of extraocular
muscles-
The muscular sheath of each extraocular
muscle sends expansions to the
surrounding structures.
Fascial expansions of lateral and medial
rectus muscles are strong
82. Which are attached to orbital tubercle on
the zygomatic bone and to the lacrimal
bone, respectively.
These are also called lateral and medial
check ligaments.
83.
84. Rectus muscle pulleys of connective
tissue and some smooth muscle fibres are
located close to the equator of globe.
These are suspended from the orbital
walls through which the rectus muscles
pass
These pulleys become the functional origin
of the muscles
85. Thus effectively modify the direction of pull
of rectus muscles.
These are stabilized by septa which are
attached to fascia bulbi, intermuscular
septa and periorbita
Expansion of superior rectus muscle is
attached to the levator palpebrae
superioris.
86. This attachment ensures synergic action
of the two muscles.
Thus, when the superior rectus makes the
eye look up, the upper lid is also raised.
In maximal levator resection for ptosis,
hypotropia can be induced if these
connections are not severed.
87. An expansion from the inferior rectus
muscle is attached to the capsulopalbebral
fascia.
An expansion from the superior oblique
passes up to the trochlea.
An expansion from the inferior oblique
passes to lateral part of the roof of the
orbit.
88. From the anterior end of the expansion
of each extraocular muscle, a fibrous
band passes to be attached to the
conjunctival culde-sac.
These connections account for the
retraction of the conjunctival sac when
these muscles contract.
89. Suspensory ligament of Lockwood-
It is a thickened sling or hammock of
fascial sheath
It extends from the posterior lacrimal
crest to the lateral orbital tubercle, on
which rests the eyeball.
90. It is formed by fusion of expansions from
the muscular sheaths of the medial rectus,
inferior oblique, inferior rectus and lateral
rectus muscle joined with the thickened
inferior part of Tenon's capsule.
91.
92. Superior transverse ligament of the
Whitnall -
It is a thickened band of orbital fascia
It extends from the trochlear pulley to the
lacrimal gland and its fossa.
It is formed by a condensation of the
superior sheaths of the levator muscle
93. Which joined medially by the sheath of the
reflected tendon of superior oblique
muscle.
It forms a true check ligament of the
levator muscle.
94. Suspensory ligaments of the fornices-
Superior suspensory ligament of the fornix
is formed by the continuation forward of
the fibrous tissue between the superior
rectus and levator muscles to the upper
fornix.
95. During ptosis surgery, if this ligament is
cut fornix conjunctiva can prolapse.
Inferior suspensory ligament of the fornix
is formed by the continuation forward up to
the inferior fornix of the fibrous tissue of
lower lid retractors
96.
97. Orbital septa of elastic and
collagenous tissue-
These septa pass inward from the
periobita to fascia bulbi
Such septa also pass to and between the
extraocular muscles and provide specific
supportive channels for the ophthalmic
veins
98.
99. Intermuscular septa/membrane-
The sheaths of the four rectus muscles are
joined to each other by a fascial
membrane called the intermuscular
septum.
This membrane divides the orbital cavity
and orbital fat into a central and a
peripheral part.
100.
101.
102. ORBITAL FAT & RETICULAR
TISSUE
Most of the orbital cavity is occupied by
orbital fat
Which extends from the optic nerve to the
orbital wall and from the apex of the orbit
to the septum orbitale.
The fat lobules lie in the interstices of a
web of reticular tissue called the orbital
reticulum
103. This tissue is the supporting framework of
the orbital fat, anchoring it to the orbital
fascia
The orbital fat is divided into central and
peripheral parts by the intermuscular
septa.
104. Posteriorly, where there is no
intermuscular septa, the peripheral and
central fat pads are continuous with each
other.
The peripheral orbital fat consists of four
lobules-
Superomedial, superolateral, inferomedial
and inferolateral.
105. Benign encapsulated tumours do not alter
the normal structure of reticular tissue and
fat except that these structures are under
great pressure and when the periorbita
has been opened, bulge more persistently
into the operative field.
106. However, in case of malignant tumours
and infiltrative lesions like pseudotumours
and endocrine exophthalmos this basic
matrix may alter depending on the nature
and duration of the lesion.
107. The orbital fat and its reticular tissue are
not as inert as is commonly assumed.
At times they may become very reactive.
Therefore, lesser the disturbance of these
structures during orbitotomy, the better the
functional and cosmetic results.
108. OPENINGS INTO THE
ORBITAL CAVITY
Orbital Opening-
The orbital opening lies anteriorly
About onesixth of the eye is exposed
The remainder is protected by the walls of
the orbit.
109. Supraorbital Notch (Foramen)-
The supraorbital notch is situated on the
superior orbital margin
It transmits the supraorbital nerve and
blood vessels.
110. Infraorbital Groove and Canal-
The infraorbital groove and canal are
situated on the floor of the orbit in the
orbital plate of the maxilla
They transmit the infraorbital nerve (a
continuation of the maxillary nerve) and
blood vessels.
111. Nasolacrimal Canal-
The nasolacrimal canal is located
anteriorly on the medial wall
It communicates with the inferior meatus
of the nose
It transmits the nasolacrimal duct
112. Inferior Orbital Fissure-
The inferior orbital fissure is located
posteriorly between the maxilla and the
greater wing of the sphenoid
It transmits the maxillary nerve and its
zygomatic branch, the inferior ophthalmic
vein, and sympathetic nerves
113. Superior orbital fissure-
It is located posteriorly between the
greater and lesser wings of the sphenoid
It transmits the lacrimal nerve, frontal
nerve, trochlear nerve ,oculomotor nerve
(upper and lower divisions),abducent
nerve, the nasociliary nerve, and the
superior ophthalmic vein.
114. Optic Canal-
The optic canal is located posteriorly in the
lesser wing of the sphenoid
It transmits the optic nerve and the
ophthalmic artery
117. Anterior and Posterior Ethmoidal
Foramina-
The ethmoidal foramina are located on the
medial wall in the ethmoid bone
They transmit the anterior and posterior
ethmoidal nerves, respectively.
118. SURGICAL SPACES IN THE
ORBIT
The orbit is divisible into a number of
spaces.
These are of importance as most orbital
tumours tend to remain within the space in
which they are formed (unless they are
large or malignant or unless they
represent an infiltrative process such as
pseudotumours)
119. Therefore, a knowledge of the main
compartments of the orbit and their
boundaries helps the surgeon in choosing
the most direct approach to the tumour
From the surgical point of view, five
spaces can be described in the orbit
120. 1.Subperiosteal space-
This is a potential space between orbital
bones and the periorbita
It is limited anteriorly by the strong
adhesions of periorbita to the orbital rim
121. Dermoid cyst, epidermoid cyst, mucocele,
subperiosteal abscess, myeloma,
osteomatous tumour, haematoma and
fibrous dysplasia are commonly seen in
this space.
Plain X-rays are most useful in diagnosing
the tumours of this space.
122. 2.Peripheral orbital space (anterior
space)-
This space is bounded peripherally by
periorbita,internally by the four extraocular
muscles with their intermuscular septa and
anteriorly by the septum orbitale (including
tarsal plates and tarsal ligaments).
123. Posteriorly, it merges with central space
Tumours in this space produce eccentric
proptosis and can usually be palpated.
Common tumours found in this space are
malignant lymphoma, capillary
haemangioma of childhood, intrinsic
neoplasms of the lacrimal gland and
pseudotumours.
124. Tumours residing in this space are
explored usually by anterior orbitotomy
and some times by lateral orbitotomy
125. Contents of this space are peripheral
orbital fat, superior oblique, inferior oblique
and levator palpebrae superioris muscles;
lacrimal, frontal, trochlear, anterior
ethmoidal and posterior ethmoidal nerves;
superior and inferior ophthalmic veins;
lacrimal gland and half of the lacrimal sac.
126. 3.Central space-
It is also called muscular cone or posterior
or retrobulbar space
This space is bounded anteriorly by
Tenon‘s capsule lining the back of the eye
and peripherally by the extraocular rectus
muscles and their intermuscular septa(in
the anterior part)
127. In the posterior part this space becomes
continuous with the peripheral orbital
space.
Contents of the central space include optic
nerve and its meninges, superior and
inferior divisions of oculomotor nerve,
abducent nerve, nasociliary nerve, ciliary
ganglion, ophthalmic artery, superior
ophthalmic vein and the central orbital fat.
128. Many of the circumscribed orbital tumours
such as cavernous haemangioma of
adults, solitary neurofibroma,
neurilemomas, nodular orbital
meningiomas and optic nerve gliomas
occur in this space and usually produce an
axial proptosis.
Such tumours are often removed through
a lateral orbitotomy.
129. 4.SubTenon’s space-
It is a potential space around the eyeball
between the sclera and Tenon's capsule.
Pus collecetd in this space is drained by
incision of Tenon's capsule through the
conjunctiva.
130. 5.Apical space-
It is bounded peripherally by periorbita;
anteriorly becoming continuous with the
anterior (peripheral) and posterior (central)
spaces, at the level of posterior limit of
intermuscular membrane and ending
posteriorly at the apex of the orbit
131.
132.
133.
134. APERTURES AT THE BASE
OF ORBIT
The base of orbit is closed partially by the
globe and extraocular muscles with their
fascial expansions
These expansions and two oblique
muscles bound about five orifices between
the orbital margin and globe
Through these orifices fat may herniate
from the orbit to come into contact with the
septum orbitale
135. These apertures form a communication
between the orbital cavity and deep
portions of eyelids
It is through them that blood and pus pass
out of the orbit from the space between
periorbita and peripheral fat
Their further spread in the lids is stopped
by septum orbitale.
136. These apertures are described as-
1.Superior aperture-
This is a comma shaped orifice and lies
between the roof of the orbit and the upper
surface of the levator palpebrae superioris
muscle.
137. Fat from the superomedial lobe may
herniate through this aperture to form a
retroseptal roll, which serves as an
important landmark during levator
resection surgery for ptosis.
138. 2.Superomedial aperture-
This vertically oval aperture lies between
the reflected tendon of the superior
oblique muscle and the medial check
ligament.
The infratrochlear nerve, dorsal nasal
artery and angular vein pass through this
aperture.
139. Herniation of fat through this aperture is a
common cause of lobulated prominence in
old people
140. 3.Inferomedial aperture-
This is vertically oval in shape
It lies between the medial check ligament,
origin of inferior oblique muscle and the
lacrimal sac.
141. 4.Inferior aperture-
This is triangular in shape
It is bounded by the inferior oblique
muscle, arcuate expansion of inferior
oblique and floor of the orbit.
142. 5.Inferolateral aperture-
This is a small oval aperture
It is situated between the arcuate
expansion of the inferior oblique muscle
and the lateral check ligament
143.
144. CONTENTS OF THE ORBIT
Eyeball occupies about one fifth of the
total orbital volume
Muscles include superior rectus, inferior
rectus, medial rectus, lateral rectus,
superior oblique, inferior oblique, levator
palpebrae superioris, and muller's muscles
of the orbit
145. Nerves include optic nerve, oculomotor
nerve, trochlear nerve, abducent nerve,
branches of ophthalmic division of Vth
nerve (lacrimal, frontal, nasociliary) and
branches of maxillary division of Vth nerve
(infraorbital, zygomatic).
146. Vessels include ophthalmic artery and its
branches, Infraorbital vessels, orbital
branch of middle meningeal artery and
superior and inferior ophthalmic veins.
Orbital fat, reticular tissue and orbital
fascia.
Lacrimal gland and lacrimal sac.
151. Congenital anomalies can affect the orbit
in two ways.
First, there can be a primary defect in the
structural architecture of the bony orbit.
This type includes defects of the anterior
cranial base and facial skeleton.
Alternatively, defects in the development
of the globe and soft tissues can induce
secondary changes in the bony orbit.
152. Most congenital and developmental
anomalies of the orbit can be classified
into three categories:
1) Localized anomalies of the orbit
2) Craniosynostosis or deformities of
premature cranial suture closure
3) Facial clefting syndromes
Others are Non specific congenital orbital
anomalies
153. LOCALIZED ORBITAL
ANOMALIES
Localized anomalies of the orbit and
periorbital adnexa are the most common
congenital defects
These "localized" problems may affect
other facial and intracranial structures.
154. MICROPHTHALMOS AND
ANOPHTHALMOS-
True anophthalmos is a rare condition that
results from failure of development or
complete regression of the optic vesicle.
It is clinically indistinguishable from severe
microphthalmos, which results from
incomplete invagination of the optic vesicle
or closure of the embryonic fissure.
155. The term clinical anophthalmos has been
used to describe patients who have no
clinical or radiographic evidence of an
ocular remnant, although true
anophthalmos can only be verified after
careful histologic sectioning of the orbital
tissues.
156. Anophthalmos and microphthalmos are
usually unilateral and can be associated
with a variety of craniofacial and systemic
anomalies, including orbital hypoplasia,
facial clefts, basal encephalocele,
hemifacial microsomia, mandibulofacial
dysostosis, cardiac anomalies,
polydactyly, and mental retardation.
157. When unilateral, they also can be
associated with anomalies of the other
"normal" eye, including cataract, corneal
opacities, microphthalmos, coloboma,
epibulbar dermoids, and nystagmus.
Unilateral microphthalmos and
anophthalmos can be associated with
secondary orbital hypoplasia
158. Anophthalmos and severe microphthalmos
frequently are associated with small
conjunctival fornices, phimotic eyelids, and
generalized hypoplasia of the periocular
soft tissues
159.
160.
161. When soft tissue contractures occur, the
early use of conformers is essential to
expand these tissues.
This treatment should be instituted in the
first month of life, with progressive
enlargement of the conformer every 2
weeks to achieve maximum expansion of
the conjunctival fornix.
162. Unfortunately, these soft tissue expanders
have minimal effect on bony orbital
growth.
In recent years surgically placed expansile
orbital implants have been advocated to
stimulate bony orbital development.
163. DERMOID CYST-
Dermoid cysts are developmental
choristomas that are believed to arise from
ectodermal rests pinched off by the fusion
of bony sutures around the orbit.
These cysts often originate from the
frontozygomatic suture temporally
But are also seen nasally, arising from the
frontonasal and frontolacrimal sutures.
164. They rarely occur deep in the orbit.
They commonly present during the first
decade of life
Presents as a well-circumscribed, firm,
rubbery subcutaneous mass just below the
temporal eyebrow.
165. Deeper dermoids can remain
asymptomatic for many years, often
presenting later in life as a slowly
expanding orbital mass.
Complete excision of these encapsulated
lesions is the preferred treatment.
Rupture of the cyst from trauma or during
surgery can result in severe orbital
inflammation
166. ORBITAL DYSTOPIA-
It is defined as a vertical malignment of the
globes.
Congenital anomalies of orbital
development are the most common cause
of orbital dystopia.
167. These anomalies include
craniosynostosis, hemifacial microsomia,
and orbitofacial clefts.
Acquired orbital dystopia can occur as a
result of facial and orbital fractures or
mass lesions that arise from the orbit,
periorbital sinuses, and adjacent
structures.
168. ANATOMIC VARIATION-
A variety of localized aberrations occur in
the bones and soft tissues of the orbit.
These aberrations include accessory
ossicles and sutures; redundant or
misplaced notches, foramina, and canals;
and variation in the orbital vascular supply.
These conditions are sporadic and rarely
have any clinical significance
169. CRANIOSYNOSTOSIS
Craniosynostosis implies premature fusion
of the bony sutures of the skull.
These craniofacial anomalies usually
display a sporadic inheritance pattern,
although several well-recognized
syndromes have distinct inheritance
patterns, such as the autosomal dominant
pattern of Crouzon's disease.
170. Although premature suture fusion was
believed to be the primary pathologic
process, evidence suggests that this early
fusion may be a compensatory change
caused by an abnormality in cranial bone
development.
171. Scaphocephaly-
It is an elongated, narrow cranium
associated with premature fusion of the
sagittal suture.
Brachycephaly-
It is a short, wide cranial vault associated
with bilateral coronal synostosis.
172. Plagiocephaly-
It results from premature closure of one
coronal suture, leading to prominent orbital
asymmetry
A flattened, recessed forehead occurs on
the affected side, and persistent growth of
the contralateral side
It results in frontal bossing, inferolateral
orbital dystopia, and a prominent occiput.
173.
174. Trigonocephaly-
It is a triangular deformity of the anterior
cranial fossa that results in medial
displacement of the orbits (hypotelorism)
175.
176. Acrocephaly-
It results from multiple suture closure,
including bicoronal synostosis.
Typically, there is excessive skull height
and a pointed head.
177.
178. CROUZON'S DISEASE-
This is a autosomal dominant disease
This can have a variety of ocular findings,
including exophthalmos, hypertelorism,
strabismus, nystagmus, and optic atrophy.
A variable pattern of suture closure is
seen, including coronal, sagittal, and
lambdoid sutures.
179. The deformities of the orbit and cranial
vault are in part a result of the
compensatory expansion of the cranium
from increased intracranial pressure.
Forward displacement of the greater wing
of the sphenoid bone results in a
shortening of the lateral orbital wall and a
dramatic reduction in orbital volume.
180. To compound the problem, there is also
inferior displacement of the orbital roof
from anterior cranial fossa expansion and
shortening of the orbital floor from
maxillary hypoplasia.
These defects account for a 6-cc reduction
in orbital volume, or approximately 20% to
25% of the total volume of the orbit.
181.
182. APERT'S SYNDROME-
Ocular findings include brachycephaly,
exophthalmos, hypertelorism, and
maxillary hypoplasia.
The distinguishing feature of Apert's
syndrome is a symmetric syndactyly of the
hands and feet.
Ptosis, an antimongoloid slant to the intra-
palpebral fissure, and oculomotor palsies
can also be seen.
183.
184.
185. TREATMENT OF CRANIOSYNOSTOSIS-
Early intervention is aimed at reducing the
intracranial pressure to permit normal
visual and mental development, and to
achieve a satisfactory cosmetic result.
186. The techniques employed include a variety
of frontal and facial bone advancements
designed to expand the intracranial
volume and improve the cosmesis of the
facial skeleton
187.
188. FACIAL CLEFTS
Facial clefts range from small, isolated soft
tissue defects to severe, disfiguring
craniofacial deformities
Tessier developed an anatomic
classification for this diverse group of
congenital anomalies
Tessier classification numbers the clefts
based on their location in relation to the
orbit
189.
190. Tessier cleft 0-14, a true median cleft, is
associated with orbital hypertelorism and
meningoencephalocele.
191.
192. Clefts 1 and 2 are associated with
telecanthus from involvement of the soft
tissues of the medial canthus, but spare
the lacrimal system and eyelids.
Tessier clefts 3 and 4 involve the
inferomedial orbit and lower eyelid medial
to the punctum.
193. Tessier cleft 5 is associated with a defect
in the inferolateral orbital rim and floor, a
lateral lower eyelid cleft and, frequently,
microphthalmia.
Features of Tessier clefts 6, 7, and 8 are
seen in Treacher-Collins syndrome,
Goldenhar's syndrome, and hemifacial
microsomia.
194. Tessier cleft 9 is characterized by defects
in the superolateral orbital rim and the
lateral one-third of the upper eyelid, and
distortion of the lateral canthus.
A central cleft of the eyebrow, upper
eyelid, supraorbital rim, and orbital roof
characterize Tessier cleft 10.
195. Tessier cleft 11 is characterized by defects
in the medial aspect of the upper eyelid
and brow, but no bony defect in the
supraorbital rim.
196. Tessier cleft 12 is associated with
telecanthus, hypertelorism, and a defect at
the medial root of the eyebrow.
Clefts 13 and 14 are characterized by
hypertelorism with sparing of the orbital
soft tissues.
197.
198.
199.
200. NONSPECIFIC CONGENITAL
ORBITAL ANOMALIES
HYPERTELORISM-
Orbital hypertelorism is defined as an
abnormally wide distance between the
orbits.
It is not a syndrome, but a physical finding
that is found in a variety of craniofacial
anomalies.
Hypertelorism implies an increased
interpupillary distance.
201. Hypertelorism is associated with a variety
of facial clefts, craniosynostosis, and
meningoencephaloceles.
The normal distance between the orbits is
roughly 16 mm at birth and increases to 25
to 28 mm in adults.
This distance is best measured by taking
the shortest distance between the medial
walls of the orbits on a transverse
computed tomography scan.
202. A widening of the anterior ethmoid air cells
is believed to be the main anatomic defect
responsible for primary orbital
hypertelorism.
The posterior ethmoid air cells and the
sphenoid bone are usually normal.
As a result, the optic foramina are usually
normal as well.
203. The cribiform plate is not widened, but can
be depressed 10 mm below its usual level,
making the extracranial approach to the
correction of this defect hazardous.
The angle between the central axis of
each orbit is normally 25°.
In orbital hypertelorism, the axes of the
orbits are more divergent, measuring up to
60° in severe cases.
204. There is an increase in soft tissue, bone,
and cartilage between the medial canthi.
Defects including nasolacrimal duct
obstruction and absence of the puncta,
have been described.
Surgical correction of hypertelorism
usually entails a combined intracranial and
extracranial approach.
205. All four walls of each orbit are
osteotomized to free them from the frontal,
zygomatic, maxillary, nasal, and sphenoid
bones.
The excessive intervening tissues are
removed, and the orbits are brought closer
together in the midline.
The resultant bone gaps are filled with
bone grafts
206.
207. MENINGOENCEPHALOCELE-
Congenital defects in the bony sutures of
the cranial skeleton can result in a
herniation of brain and meninges into the
orbit, known as meningoencephalocele
This defect usually occurs medially
between the sutures of the frontal,
ethmoidal, lacrimal, or nasal bones.
208. A soft, pulsatile mass that bulges with
coughing and valsalva appears in the
upper medial canthal area during the first
years of life.
Rarely, a congenital dehiscence in the
greater wing of the sphenoid bone results
in a slowly progressive pulsatile,
exophthalmos that presents later in life.
209. HEMIFACIAL MICROSOMIA-
Complex disorder of unknown etiology
It is characterized by facial asymmetry
with ipsilateral abnormalities of the middle
ear, mandibular ramus, and condyle.
Dystopia can result from hypoplasia of the
orbital bones.
Associated systemic defects can involve
the heart, kidneys, and limbs.
210. OCULOAURICULAR DYSPLASIA-
Also known as Goldenhar's syndrome
It is a unilateral disorder characterized by
malformations of the eye, ear, and malar
and vertebral structures
It is a variant of hemifacial microsomia.
211. Soft tissue findings include epibulbar
dermoids, orbital lipodermoids,eyelid
colobomas, preauricular appendages, and
aural fistulas.
Marked facial asymmetry can occur due to
unilateral hypoplasia of the zygoma,
mandible, and chin.
Abnormalities of the cervical vertebrae
have been shown.
212.
213. PROGRESSIVE HEMIFACIAL
ATROPHY-
Also known as Romberg's syndrome
It is a rare disorder characterized by
progressive atrophy of the skin,
subcutaneous tissue, muscle, cartilage,
and bone
Usually involving only one side of the face.
214. This condition has been associated with a
variety of ocular findings, including
progressive enophthalmos, heterochromia,
uveitis, restrictive strabismus, papillitis,
retinal vasculitis and oculomotor nerve
palsy.
215. MANDIBULOFACIAL DYSOSTOSIS-
Also known as Treacher-Collins syndrome
or Franceschetti syndrome
It is a bilateral, autosomal dominant
condition that results from abnormal
development of structures derived from
the first and second branchial arches
216. Hypoplasia of the maxilla, mandible, and
zygoma are associated with a variety of
soft tissue malformations.
These malformations include
underdevelopment of the midfacial
musculature, lower eyelid colobomas,
inferior displacement of the lateral canthi
(antimongoloid slant), inferior punctal
agenesis, and blepharoptosis.
217. Additional ocular anomalies may include
high myopia, dermolipoma, lens
subluxation, and secondary glaucoma.
218.
219. PIERRE ROBIN SYNDROME-
It is characterized by micrognathia,
glossoptosis, cleft palate, and respiratory
distress from airway obstruction at the
level of the tongue.
Associated ocular disorders include
microphthalmia, congenital glaucoma, and
high myopia, with associated retinal
detachments.
220. FIBROUS DYSPLASIA-
Fibrous dysplasia is a benign disorder
characterized by an arrest of bone
maturation that results in immature bone
and osteoid in a cellular fibrous matrix.
This congenital disease usually becomes
clinically apparent in children and young
adults.
221. It occurs in both monostotic and
polyostotic forms.
Polyostotic fibrous dysplasia sometimes is
associated with cutaneous cafe’au lait
spots, endocrine abnormalities, and
precocious puberty in girls,known as
Albright's syndrome
222. Approximately one-third of all fibrous
dysplasia patients show involvement of the
facial bones or skull
The maxillary, frontal, and sphenoid bones
are most commonly involved.
Maxillary bone involvement can cause
nasolacrimal duct obstruction.
223. Involvement of the frontal and sphenoid
bones can result in orbital asymmetry from
contour deformities, vertical dystopia, and
exophthalmos.
Radiographically, fibrous dysplasia
appears as an expansile bone lesion with
a characteristic ground-glass appearance
224. Additional ocular complications include
compressive optic neuropathy, oculomotor
nerve palsy, and trigeminal neuralgia.
Involvement of the sphenoid bone can
result in narrowing of the optic canal, with
secondary compressive optic neuropathy
225. Definitive treatment entails unroofing the
optic canal by way of a transcranial
approach, although high-dose steroids can
be used as a temporizing measure.
Fibrous dysplasia is not a true neoplasm;
however, there is a small incidence of
malignant degeneration, usually into
osteogenic sarcoma
226. Treatment options range from careful
observation to aggressive debulking of the
diseased bone, with subsequent
reconstruction
Recent advances in craniofacial surgery,
including cranial bone grafting with mini-
and microplate fixation, have made the
latter approach more appealing.
227.
228. ANENCEPHALY-
Partial or total absence of the brain
It is a severe congenital birth defect
incompatible with life.
This dramatic deformity results from failure
of forebrain development.
229. The vault of the skull is absent, and the
forebrain consists of a degenerated mass
of glial tissue.
The orbits are shallow and tilted upward.
The eyes are fairly well developed, but the
optic nerves, when present, taper down to
a loose mass of glial tissue at the optic
canal.
230. CYCLOPIA/SYNOPHTHALMOS-
True cyclopia (cyclopia sensu stricto) is a
rare congenital anomaly characterized by
a single eye situated in a single median
orbit.
Synophthalmos (cyclopia sensu lato) is
much more common than true cyclopia,
occurs when paired ocular structures are
found in a single median orbit
