3.5 Eye Blocks Flashcards
Innervation of Eye
Globe receives: Motor Sensory Autonomic Nerve trunk enter eye back orbit through superior optic canal + inferior orbital fissure
Motor
Extra ocular
Enters superior orbital fissure
LR6SO4 3
Superior oblique - CN 4 -
Trochlear
Lateral Rectus - CN 6
Abducens
Remain Ex Occ muscle - CN III
Oculomotor
incl lev palpebrae superioris
Autonomic
Dilation:
Pupillary muscles
Allows diameter of pupil
alter amount light conveyed retina
Dilation: Contraction dilator pap muscle Sympathetic impulse along short + long ciliary N. Originating superior cervical ganglion Mydriasis
Constriction:
Constriction: Meiosis Parasympathetic fibres Edinger Westphal Nucleus oculomotor
Synapse Ciliary ganglion
Short post ganglionic ciliary N
innervate circular constrictor
Sensory
Branch trigeminal:
Skin eyelid
Conjunctiva
Ophthalmic div ->
lacrimal
nasociliary
front N.
Maxillary division
infra orbital nerve
Special sensory greater petrosal from Facial N. Geniculate ganglion PS autonomic -> pterygopalatine ganglion Lacrimation -< lacrimal gland
Optic N.
Impulse from retina to Chiasm
Techniques
Retrobulbar
Peribulbar
Retrobulbar
Intraconal injection
40mm 25g needle
Perc or transconjunctival tech possible
Inferotemporal quadrant chosen area
- relative deficiency in blood vessel
Check Axial length
C/I >26mm
Retrobulbar
Technique
Injection point
in line lateral edge iris
Advance 1cm
Angle superomedially
piercing muscle cone
Eye bob downards - penetrating cone
Aspirate + inject 4-5ml LA
Less popular:
Globe perf
NV injury
Supplemental Facial n
- orbicularis oculi
Peribulbar
Extraconal injection
Larger dose 5-10ml LA
Shorted needle
aim not to pass equator globe
Injection point as for retrobulbar tech
Needle advance posteriorly touch posterior wall orbit
Aspirate + inject 5-10ml LA
May require medial injection
2-5ml LA
medial caruncle
Additional facial N
usually not required
