Proptosis
Balasubramanian Thiagarajan
Otolaryngology online
Definition
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Proptosis is defined as abnormal protrusion of eye
ball
If protrusion of globe is 18 mm / less it is known as
proptosis
If protrusion of globe is more than 18 mm it is
known as exophthalmos
Proptosis + lid lag = exopthalmos
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Exorbitism
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This is caused due to decrease in the volume of orbit
causing the orbital contents to protrude forwards
Usually bilateral
Should be differentiated from proptosis /
exophthalmos
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Difference between proptosis /
exophthalmos
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Anatomy of orbit
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Volume of orbit is fixed
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30 ml
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Increase in soft tissue
volume of 5 ml will
cause 5 mm of proptosis
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Anatomy of orbit - 2
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Resembles a four sided
pyramid
Rim is 40 mm horizontally
and 35 mm in an adult male
Medial walls are parallel
and 25 mm apart in adults
Lateral orbital walls angle
about 90 degrees from each
other
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Orbital rim
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Superior orbital rim is formed by frontal bone
Inferior rim is formed by maxillary bone medially
and zygomatic bone laterally
Lateral orbital rim is formed by zygoma
Superior rim contains a notch at the junction of
medial and lateral thirds (supraorbital notch)
Medial portion of the rim is formed by frontal
process of maxilla
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Lacrimal fossa
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Lodges the lacrimal sac
This fossa is formed by
maxillary and lacrimal
bones
Bounded by anterior and
posterior lacrimal crests
Anterior crest is formed by
maxillary bone
Posterior lacrimal crest is
formed by lacrimal bone
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Weber's suture
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Lies anterior to lacrimal fossa
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Also known as sutura longitudinalis imperfecta
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This suture runs parallel to anterior lacrimal crest
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Infraorbital nerve artery branches pass through it to
supply nasal mucosa
Bleeding occurs from these vessels during lacrimal
sac surgeries
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Embryology
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7 bones involved in the formation of orbit are
derived from neural crest cells
Ossification of orbit is complete at birth excepting
its apex
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Lesser wing of sphenoid is cartilagenous
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Other bones undergo membranous ossification
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Orbital roof
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Formed by frontal bone
Posterior 1.5 cms of the roof is formed by lesser
wing of sphenoid
Optic foramen contains optic nerve
Optic nerve enters orbit at an angulation of 44
degrees
Lacrimal gland is located at the lateral end of orbital
roof
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Medial orbital wall
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Formed by frontal process of maxilla, lacrimal bone,
ethmoidal bone and lesser wing of sphenoid
Thinest portion of medial wall is the lamina
papyracea
It separates orbit from the nasal cavity
Infections from ethmoidal sinuses can breach this
bone and spread into the orbit.
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Medial wall of orbit applied anatomy
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Lacrimal bone at the level of lacrimal fossa is very
thin
This bone can easily be penetrated during
endoscopic DCR
If the maxillary component is predominant then it is
really difficult to breach this bone during endoscopic
DCR since this bone is rather thick.
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Fronto ethmoidal suture line
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Very important surgical landmark
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Marks the approximate level of ethmoidal roof
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Dissection above this line will expose the cranial
cavity
Anterior and posterior ethmoidal foramina are
present in this suture line
Anterior and posterior ethmodial arteries pass
throught these foramina
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Orbital roof
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Roof of orbit is formed by frontal bone
Posterior 1.5 cm of roof is formed by lesser wing of
sphenoid
Optic foramen is located in the lesser wing of
sphenoid
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Floor of orbit
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It is the shortest of all the walls
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Bounded laterally by infraorbital fissure
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Medially bounded by maxilloethmoidal strut of bone
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Almost entirely formed by orbital plate of maxilla
with minor contribution from orbital plate of
palatine bone posteriorly
Floor is thin medial to infra orbital groove
Infraorbital groove becomes infraorbital foramen
anteriorly
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Lateral wall
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Formed by greater wing of sphenoid
Zygoma & zygomatic process of frontal bone –
minor contribution
Recurrent meningeal branch of middle meningeal
artery is seen in this wall
4-5 mm behind the lateral orbital rim and 1 cm
inferior to the fronto zygomatic suture line lie the
whitnall's tubercle.
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Whitnall's tubercle (structures attached)
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Lateral canthal tendon
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Lateral rectus check ligament
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Suspensory ligament of lower eyelid (Lockwood's
ligament)
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Orbital septum
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Lacrimal gland fascia
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Anatomical relationship of orbit with
paranasal sinuses
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By its location – it is closely related to all paranasal
sinuses
By venous drainage – Both these areas share a
common venous drainage
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Peculiarities of orbital venous drainage
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Entire venous system is devoid of valves – hence
two way communication between orbit and sinuses
is a reality
Superior opthalmic vein connects facial vein to
cavernous sinus – causing spread of infections from
face to cavernous sinus
Inferior ophthalmic vein communicates with
pterygoid venous plexus and cavernous sinus by its
two branches
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Pseudoproptosis
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High myopia
Enophthalmos of one eye may cause apparant
proptosis of the other one
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Exophthalmometer
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Hertel's mirror
exophthalmometer is
used for this purpose
The distance between
the lateral orbital rim
and the corneal apex is
used as a measure for
proptosis
This distance is
normally 18 mm
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ENT - Causes
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Mnemonic – VEIN
V – Vascular causes
E – Endocrine causes
I – Inflammatory causes
N – Neoplastic causes
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Imaging
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CT / MRI may help in
identifying the cause
Fat in the orbit serves as
a contrast medium
3 mm cuts is ideal
Ultrasound – A mode /
B mode can be done to
identify the cause
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Role of MRI
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MRI is sensitive in identifying extraocular muscle
oedema
Increased T2 relaxation time indicates extraocular
muscle oedema, these pts respond well to steroid
therapy
Patients with normal T2 relaxation levels need
orbital decompression
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Vascular causes
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Classified into arterial and venous
Venous causes are due to dilated veins – Positional
proptosis is the classical feature in these patients. It
can also be induced by valsalva maneuver
Initially there may be atrophy of fat in these pts
causing enophthalmos
CT scan after jugular vein compression is diagnostic
Surgery is disastrous in these patients. Conservative
management is the best modality
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Proptosis due to dural venous sinus
fistula
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Shunt is low flow type
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Proptosis is insidiuous and often goes unnoticed
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A high index of suspicion is necessary to diagnose
these cases
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Carotid cavernous fistula
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High flow shunts
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Can occur spontaneously / trauma
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Subjective bruit / proptosis / chemosis / vision loss
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Arterolization of conjunctival vessels causing
corkscrew pattern
Intractable cases – shunt must be closed using
balloon / carotid artery ligation
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Endocrine proptosis - features
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Presence of lid lag / retraction
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Presence of temporal flare in upper eyelid
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Presence of orbital congestion
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Imaging shows enlarged extraocular muscles,
bulging of orbital septum due to fat protrusion
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Inflammatory causes
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Idiopathic inflammation – Pseudotumor of orbit
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Due to specific causes of orbital inflammation
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These pts have pain during ocular movement
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Associated dacryo adenitis +
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Perioptic neuritis can cause blindness
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Steroids may be helpful
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Neoplastic lesions involving nose and
sinuses
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Inverted papilloma
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Fungal infections
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Mucoceles of paranasal sinuses
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Fibrous dysplasia of maxilla
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Osteomas involving frontal / ethmoidal sinuses
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JNA
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Management
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Low dose irradiation (rarely used)
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Surgery
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Indications for orbital decompression
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Visual disturbance due to proptosis
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Failure of steroids to improve vision
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If steroids are necessary on a long term basis for
maintaining vision
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To preven exposure keratitis
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Diplopia
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Cosmesis
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Risks of orbital decompression
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Diplopia
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Intractable strabismus
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Hypoglobus
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Injury to optic nerve due to prolonged globe
retraction
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Retrobular hematoma – this can cause blindness
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Injury to infraorbital nerve
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Epistaxis
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Orbital decompression (Goals)
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To enlarge the confining space of orbit by removing
1-4 of its walls
15 mm of decompression can be achieved by
removing all 4 walls of the orbit
Usually successful surgery causes 3-7 mm
decompression of orbit
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Superior orbital decompression
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Naffzeiger technique
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Superior wall decompression
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Complete unroofing of orbit – frontal craniotomy
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Large amounts of bone can be removed creating
more space
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Craniotomy may be needed
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Used in pts with orbital trauma
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Naffzeiger --- Contd
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In collaboration with neurosurgeon
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Optic nerve should be visualized to begin with
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The roof of the orbit is removed starting from the
optic foramen to the anterosuperior orbital rim
Periosteum should be left intact to prevent injury to
levator muscle
H shaped incision is made over superior periosteum
allowing orbital fat to prolapse through it
Titanium mesh can be
used to cover orbital roof
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Medial orbital decompression
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Also known as Sewell procedure
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Coronal incision / external ethmoidectomy incision
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Medial canthal tendon is identified and divided
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Anterior and posterior ethmoidal arteries identified
and clipped
Complete ethmoidectomy is performed starting from
lacrimal fossa
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Bicoronal incision for medial orbital
decompression
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Medial canthal tendon can be left intact
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Ethmoidectomy is performed from above
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Lacrimal sac and trochlea should not be damaged
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Medial periosteum is incised and orbital fat is
allowed to prolapse into the nasal cavity
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Inferior decompression
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Hisch and Urbanek procedure
Artificial creation of blow out fracture of orbital
floor sparing infra orbital nerve
Trans conjunctival / subciliary incision plus
Caldwell Luc procedure
Laterally floor can be removed up to zygoma and
medially up to lacrimal fossa
Posteriorly bone is thick – 3 cms of bone can be
removed from this area
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Inferior decompression -- Contd
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Periosteum is incised to allow orbital fat to prolapse
into the maxillary antrum
Forced duction test should be performed to ensure
orbital muscles are not entrapped.
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Lateral decompression
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Kronlein procedure
Coronal incision, and lateral extension of subciliary
incision
Extended lateral canthotomy
Lateral orbital rim periosteum is exposed from
zygomatic arch to zygomatico frontal suture
Periosteum incised along lateral orbital rim and
orbital fat is teased out
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Combination of approaches
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Any of the above said approaches can be combined
for optimal benefit
Combination of apporaches reduces the surgical risk
and provides more increase of space than one
procedure alone
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Endoscopic decompression
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Inferior and medial orbital walls can be accessed
easily using nasal endoscope
A large middle meatal antrostomy is performed – 30
degree endoscope is used to identify the position of
inferior orbital nerve in the roof of maxillary sinus
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Total ethmoidectomy is performed
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Sphenoid osteum is identified and enlarged
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Endoscopic decompression ---Contd
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Lamina papyracea is exposed
Position of anterior & posterior ethmoid arteries
noted
If middle turbinate is resected it helps in post op
cleaning. If left behind it prevents excessive
collapse of orbital fat
Lamina papyacea is remove bit by bit using Freer's
elevator. It should be cracked in the middle portion
first
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Endocopic decompression --- Contd
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Initially periorbita is left intact to prevent orbital fat
prolapse which could obstruct vision
Bone is to be removed up to the roof of the ethmoid
superiorly, face of the sphenoid posteriorly, the
nasolacrimal duct anteriorly.
Inferiorly it can be removed up to maxillary
antrostomy
Small piece of bone is retained over frontal recess
area to prevent orbital fat obstruction frontal sinus
drainage
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contd
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Starting posteriorly periorbita is incised
Sickle knife is kept superficial to avoid injury to
extraocular muscles
Mutliple cuts are made in the periorbita allowing
orbital fat to prolapse into the nasal cavity
Exophthalmos of up to 3.5 mm can be corrected by
endoscopic decompression
Nasal packing is to be avoided to prevent optic nerve
compression
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Tips
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Nose blowing is to be avoided for 2 weeks following
surgery
Bilateral decompression should be done within an
interval of a week
For mild exophthalmos 2-3 mm any of the
approaches would suffice
For moderate – 3-5mm inferior decompression is
sufficient
For severe ones – 5-7 mm three wall decompression
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is preferred
Thank You
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