1. The document summarizes the anatomy of the orbital spaces and their clinical importance. It describes the four main anatomical spaces in the orbit - subperiosteal, peripheral orbital, central, and sub-Tenon's space. 2. The spaces are important because benign tumors typically remain within their space of origin, while large, malignant, or infiltrative tumors can spread beyond their original space. Understanding the orbital anatomy helps determine the surgical approach for orbitotomy or local anesthesia techniques. 3. Common pathologies are described for each space, such as dermoid cysts in the subperiosteal space and cavernous hemangiomas in the central space. Imaging features and clinical presentations of select conditions are

1. Anatomy of Orbital
Spaces & its clinical
importance
Presenter- Dr. Shashank Agarwal
Dr. Kanika Godani
Moderator- Dr. Ganesh C. Kuri

2. Anatomy of Orbit

3. Gross Anatomy
Dimensions
Depth – about 42 mm(40-45 mm) along the medial wall
- about 50 mm along the lateral wall.
Base width- 40mm, height- 35mm.
Intraorbital width - 25mm
Extraorbital width- 100mm
Volume of each orbit about 29-30 ml.
Ratio between the volume of orbit and eyeball- 4.5:1.

8. Anatomical spaces in the Orbit
The orbit is divisible into a number of spaces.
1.Subperiosteal space
2.Peripheral orbital space (anterior space)
3.Central space
4.Sub-Tenon’s space

9. 1. Subperiosteal space
Space between orbital bones and the periorbita,
limited anteriorly by the strong adhesions of
periorbita to the orbital rim.
Tumors arising from the bones separate periorbita
from the bone, which becomes thicker and tougher
forming an effective barrier against spread of the
tumor towards the eye.

11. 2. Peripheral anterior space/ Extraconal
space
- bounded peripherally by periorbita, internally by the 4
EOM with their intermuscular septa and anteriorly by
the septum orbitale.
- Posteriorly merges with the central space.
- Contents include peripheral orbital fat, SO, IO, LPS,
lacrimal, frontal, trochlear nerves, ant & post.
Ethmoidal N, sup. And inf. Ophthalmic V., lacrimal
gland and half of lacrimal sac.

13. 3. Central space/ Intraconal space
- aka Muscular cone / posterior/ Retrobulbar space.
- Bounded anteriorly by Tenon’s capsule lining the back
of the eye, peripherally by EO rectus muscles and their
intermuscular septa
- Posteriorly, space becomes continuous with peripheral
orbital space.
- Contents include optic N & its meninges,
occulomotor(sup. & inf. Div), abducent, nasociliary N,
ciliary ganglion, ophthalmic A, superior ophthalmic V
and the central orbital fat.

14. 4. Sub-Tenon’s space
- Space around the eyeball between the sclera and
Tenon’s capsule.

15. • malignant lesion-
1. irregular margin
2. INFILTERTION INTO THE ADCENT STRUICTUYRE
3. BONY EROSION
4. HETEROGENOUS INTERNAL CONSISTENCY
5. EXTRAORBITAL EXTENSIION
6. Fast growing

16. Diseases in subperiosteal space
• Dermoid cyst
• Epidermoid cyst
• Mucocele
• Subperiosteal abscess
• Myeloma
• Hematoma
• Fibrous dysplasia

17. Dermoid
• Choristoma-Normal tissue at abn place
• Lined by stratified squamous
epithelium
• Fibrous wall
• Sweat gland, sebaceous glands, hair
follicles
• Superficial and deep
• Painless, superotemporal , firm ,round,
smooth , non tender, adhere to
periosteum, post margin palpable
• Deep – proptosis, dystopia, indistinct
post margin
• Ct scan- well circumscribed
heterogenous lesion
• Can erode bone, extend intracranially
or inferotemporal fossa
1. Ct /mri
2. Orbit/brain/ both
3. Plain/ contrast enhanced
4. Axial/coronal/saggital
5. Level of scan
6. Abnormalities
7. Lesion – size, shape location,
number, margin, internal
consistency, surrounding
tissue, surrounding bone, ;
extraorbital extension
8. Benign/
malignant/vascular/cystic
9. Diagnosis
mid axial section of plain ct scan of orbit
and brain showing proptosis of left eye
with single well defined oval isodense mass
present behind the globe and pushing the
lateral wall of orbit. suggestive of a benign
lesion and it could be orbital dermoid

18. Sinus mucocele
• Infection, allergy, trauma, tumour,
congenital narrowing
• Obstruction of drainage of paranasal
sinus
• Accumulation of mucoid secretion
• Erodes the bony walls of sinus
• Causing proptosis or dystopia

19. Sub-Perisoteal Abscess
• Commonly occurs from ethmoidal sinusitis, extending into the orbit via
the lamina papyracea but can also occur secondary to frontal sinusitis.
• Mass effect on MR
• Opacification of ethmoid cells
• Iv antibiotics
• External drainage
• Transnasal endoscopic drainage
• if any of the following criteria are present, then surgical intervention is
warranted:
• Presence of frontal sinusitis
• Large, non-medial SPA
• Suspicion of anaerobic infection (presence of gas in abscess on CT)
• Re-accumulation of SPA after previous drainage
• Evidence of chronic sinusitis (e.g., nasal polyps)
• Acute optic neuropathy

20. Peripheral orbital space tumors
• Orbital varices
• Capillary hemangioma
• Lymphoma
• Lacrimal gland tumours
• Pseudotumors

21. Orbital varices
• Venous- lymphatic
malformation
• Thin walled, distensible , vein
like vessels of low flow nature
• M/c cause for spontaneous
orbital hemorrhage- painful
proptosis
• Stress proptosis-Increase in
venous pressure- distension
of lesion
• Ct scan- varices may be
smooth contoured, or
segmentally dilated or
tangled mass, along with
contrast enhancemet.

22. Capillary haemangioma
• most common tumour of the orbit and
periorbital area in childhood.
• Girls are affected
• Hamartoma
• Superficial cutaneous lesion- bright red
• Deeper preseptal- dark blue
• Deep orbit- u/l proptosis, no
discoloration
• Can be extraconal or anterior orbit
• Usg- medium internal reflectivity
• CT scan- lobulated, heterogenous mass
with irregular margin and Contrast CT-
homogenous enhancement of soft
tissue mass

23. Pleomorphic lacrimal gland
adenoma
• m/c epithelial tumour
• Painless
• Palpebral lobe- upper lid swelling
without dystopia
• Orbital lobe- smooth, firm, non
tender, mass in lac gland fossa,
inferonasal dystopia, post
extension causes proptosis
• Ct scan –round mass, smooth
outline, indent the globe, no
bony erosion
• Pain is frequent feature
• Inferolateral dystopia
• Post extension- superior
orbital fissure, proptosis
• CT scan– irregular serrated
edges, bony erosion
Lacrimal gland carcinoma

24. Idiopathic orbital inflammatory
disease
• non-specific orbital inflammation or orbital
pseudotumor
• non-neoplastic, non-infective, space
occupying orbital infiltration with
inflammatory features
• Acute or subacute ocular and periocular
redness, swelling and pain
• Proptosis
• Mild to severe ophthalmoplegia
• Frozen orbit-ophthalmoplegia +ptosis
+visual impairment
• CT scan- ill defined orbital opacification and
loss of definitions of contents

25. Tumors of central space
• Cavernous hemangioma
• Optic nerve glioma
• Optic nerve sheath meningioma
• Neurilemomas
• Solitary neurofibroma

26. Cavernous haemangioma
• Middle age, female
• m/c orbital tumour in adult
• Lateral part of muscle cone ,
behind the globe
• u/l axial proptosis
• Encapsulated mass
• Ct/mri- well circumscribed oval
lesion, slow contrast
enhancement

27. Optic nerve glioma
• Ass with NF1
• Age = 6yr -8yrs
• Slowly progressive visual
loss
• Non axial proptosis, inferior
dystopia
• Intracranial spread
• Mri/ ct- fusiform
enlargement of the optic
nerve

28. Optic nerve sheath meningioma
• Primary uncommon
• Gradual loss of vision
• Most meningioma of ON
sheath arises from the
extension of prim intracranial
lesion
• Tumour encircles the optic
nerve
• Ass with NF2
• Mri- tram track sign

29. LYMPHOMA
• Asymptomatic
• Double vision, bulging eye or visible
mass- Rubbery consistency
• Any part of the orbit affected
Ct scan- homogeneous mas, either
isodense or slightly hyperdense when
compared to the extraocular muscles

30. Subtenons space
• Subtenons block
• Fluid and abscess accumulate in this space

31. 3
1. Peribulbar block
2. Retrobulbar block
3. Episcleral block(sub tenons block)
4. Medial canthal block
4

32. Importance of orbital spaces
• Benign tumors remains in their space of origin
• Large or malignant or infilterative tumour spreads beyond their origin
• Deciding the approach for orbitotomy
• Anesthesia

33. Thank you