Orbital spaces

Orbital spaces and its importance in ocular anesthesia

1. ORBITAL SPACES & ITS IMPORTANCE IN OCULAR ANAESTHESIA DR. ANKITA MAHAPATRA 1 ST YR PG, DEPARTMENT OF OPHTHALMOLOGY VSSIMSAR,BURLA

2. Orbit is divided into 4 surgical spaces : INTRODUCTION :

3. SUBPERIOSTEAL SPACE Potential space between the periorbita and the orbital bones Limited anteriorly by the strong adhesions of periorbita and orbital bones

4. Tumors arising from the bones separate periorbita from the bones, which then becomes thicker & tougher, forming an effective barrier against spread of tumor towards the eye, unless subjected to extreme pressure for a long time. Tumours arising in this space: 1.DERMOID CYST 2.EPIDERMOID CYST 3.MUCOCELE 4.SUBPERIOSTEAL ABSCESS 5.MYELOMA 6.OSTEOMATOUS TUMOUR 7.HEMATOMA 8.FIBROUS DYSPLASIA PLAIN X-RAYS ARE MOST USEFUL IN DIAGNOSING THE TUMORS OF SUBPERIOSTEAL SPACE.

5. PERIPHERAL/ ANTERIOR / EXTRACONAL Between the periorbita and the muscle cone with its fascia BOUNDED , Peripherally by periorbita Internally by the four recti with their intermuscular septa Anteriorly by the septum orbitale Posteriorly, it merges with the central space

6. CONTENTS : Peripheral orbital fat Muscles : SO,IO,LPS Nerves : Lacrimal, Frontal, Trochlear, Anterior ethmoidal, Posterior ethmoidal Veins : Superior ophthalmic, Inferior ophthalmic Lacrimal gland Lacrimal sac

7. TUMOURS IN PERIPHERAL ORBITAL SPACE: MALIGNANT LYMPHOMA CAPILLARY HEMANGIOMA OF CHILDHOOD INTRINSIC NEOPLASM OF LACRIMAL GLAND PSEUDOTUMOUR Tumors in this space are usually approached by anterior orbitotomy & sometimes by lateral orbitotomy. -Tumors in this space produce eccentric proptosis and can usually be palpated.

8. INSERTION POINT: 1 st : - Junction of medial 2/3rd and lateral 1/3rd of lower lid adjacent & Parallel to orbital floor 2 nd - Just infero -medial to supra orbital notch or just medial to medial canthus U S ES O F P ERI B UL B A R B L O C K : Cataract Glaucoma Keratoplasty Vitreoretinal surgery Strabismus surgery PERIBULBAR BLOCK :

9. CENTRAL/ INTRACONAL POSTERIOR/ RETROBULBAR SPACE BOUNDED Anteriorly by the tenons capsule, P eripherally by the EO rectus muscles and their septa Posteriorly continues with the peripheral orbital space

10. INTRACONAL SPACE CONTENTS : Central orbital fat Vessels Ophthalmic artery Superior Ophthalmic Vein Nerves Optic nerve (with its meninges) Oculomotor Superior and inferior divisions Nasociliary Abducent Ciliary ganglion

11. TUMOURS IN CENTRAL SPACE : CAVERNOUS HEMANGIOMA, AV MALFORMATIONS, SOLITARY NEUROFIBROMA MENINGIOMA, OPTIC NERVE GLIOMA Produce axial proptosis. Such tumours often removed through a lateral orbitotomy

12. SITE OF INJECTION: In the lower lid margin just above a point between medial 2/3 rd & lateral 1/3 rd of lower orbital margin. SUCCESS- successful retrobulbar block is accompanied by anesthesia, akinesia, and abolishment of the oculocephalic reflex ( ie , a blocked eye does not move during head turning). RETROBULBAR BLOCK:

13. COMPLICATION : Retrobulbar haemorrhage Globe penetration Optic nerve sheath injury Optic nerve atrophy Retinal vascular occlusion Brain stem anaesthesia Frank convulsion Extra ocular muscle palsy Trigeminal nerve block Oculo-cardiac reflex Respiratory arrest

14. SUB-TENON’S SPACE Potential space around the eyeball between the tenons and the sclera. Anterior and posterior subtenons injections are given. Abscesses are drained by incising the conjunctiva

15. Conjunctival incision halfway between inf. limbus & fornix to open into post. sub-tenon space D i ssect i on Infiltration PARABULBAR OR SUB-TENON BLOCK :

16. Knowledge of the main compartments of the orbit & their boundaries helps in choosing the most direct approach to the tumor . As most orbital tumors tend to remain within the space in which they are formed unless they are large ,malignant or infiltrative pseudotumor which spreads beyond

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