Download Ocular anesthesia

OCULAR ANESTHESIA
ANANT VIR JAIN
THE PURPOSE OF ANESTHESIA IS
TO SAFELY PROVIDE COMFORT FOR
THE PATIENT WHILE OPTIMIZING
THE CONDITION FOR SURGEON
SELECTION OF ANESTHESIA
A number of factors influence the choice of
anesthesia:
The anticipated complexity and duration of the
surgical procedure.
The patient's medical status (e.g., the presence of
cardiopulmonary disease or coagulopathy).
The patient's emotional status and ability to
cooperate.
The surgeon's skill and preference.
The anesthesiologist's skill and preference.
TYPES
Retrobulbar
Peribulbar
parabulbar
Topical
Topical with intracameral
Facial
General
LOCAL ANESTHESIA AGENTS
Xylocaine 2%
Xylocaine 2% with adrenaline 1:200000
Xylocaine 4%
Bupivacaine .5%
Hyaluronidase 25 to 75 I.U. /ml
RELEVANT ORBITAL ANATOMY
Orbital rim is usually 35mm
vertically and 40 mm
horizontally in diameter
Depth from infra orbital rim to
orbital foramen is 42 to 54mm
RETROBULBAR ANESTHESIA
injection of local anesthetic into the muscle cone
in the retrobulbar space
An effective retrobulbar block results in ocular
akinesia, anesthesia of the ocular surface, and
internal ophthalmoplegia of the iris sphincter and
ciliary muscle
TECHNIQUE
Use a sharp or dull l.5-inch., 25-gauge needle with a 5rnl syringe
Length of needle should ideally be less than 33mm
Instill topical proparacaine in the upper and lower
conjunctival fornices (optional)
Palpate the inferior orbital margin at its outer one third
and clean the skin in this area with an alcohol swab
direct the patient to gaze primary gaze, Which keeps
the optic nerve out of the needle's path
Introduce the needle along the inferior orbital rim at the
junction of its outer one-third and inner two-thirds
The needle should be parallel to the orbital floor for
approximately the first 1 cm of its insertion, then
directed medially toward the orbital apex as it is
advanced posteriorly
As the muscle cone is entered, resistance can
frequently be felt if the Atkinson needle (dull) is used
Aspirate with the plunger, if no blood is seen in the
syringe, perform a slow deliberate injection of the
anesthetic agent (3 to 4 ml) with infiltration along the
track of the needle as it is withdrawn
Inject slowly 1 ml / 10 second
Immediately after withdrawing the needle, close the lids
and apply pressure to the eye with the flat of the hand
over a gauze square. Maintain pres- sure for
approximately 60 seconds
If considerable proptosis exists or the globe feels firm,
apply additional pressure, but for no longer than 60
seconds at a time
Retract the lids manually and examine the eye for signs
of retrobulbar hemorrhage
COMPLICATIONS
Chemosis
Sub conjunctival haemorrhage
Retrobulbar haemorrhage
Globe perforation
Intrathecal injection
strabismus
Peribulbar
the injection of anesthesia is "deliberately" extraconical, introduced about 15 years ago to reduce
the incidence of complications associated with
the intra-conical injection
usually produces good anesthesia but bulbar
akinesia is usually incomplete except when
considerable volumes of anesthetic are injected
technique
injection of 7-10 mI of anesthetic split into two
administrations
the first inferotemporal injection ( 4-5 mI) differs
from the Retrobulbar because the needle is not
angled and it is not moved centrally once the
bulbar equator has been exceeded
The second injection is performed in a
superonasal position (4-5 mI) more proximally on
the edge of the superior rectus muscle
As the considerable volume of anesthetic used,
it is necessary to perform adequate ocular
pressure to obtain the adequate conditions of
intraocular tension
Complications same as retrobulbar but less
frequency
PARABULBAR (SUB TENON)
Sub Tenonian space extends from the limbus to
sub-dural space of the optic nerve
An anesthetic solution injected in the subTenonian space spreads along the eye- bulb, in
the retrobulbar space as far as the optic nerve,
eyelids and extra ocular muscles
The sub- Tenonian injection produces good
anes- thesia of the iris and the anterior segment,
and akinesia is proportional to the volume of the
anesthetic injected
TECHNIQUE
The conjunctiva and the Tenon capsule are
opened 2- 3 mm from the limbus with Vannas or
Westcott scissors, following appropriate
cauterization
the injection is normally performed in the superonasal quadrant
Greenbaum polyethylene cannula with a flat
edge facing downwards is introduced in to the
sub- Tenonian space until the base of the
cannula closes the opening forming a fold in the.
conjunctiva
Once the cannula has been positioned, 1-1.5 mI
of solution is injected under sufficient pressure to
diffuse the anesthetic posteriorly. The anesthetic
effect is immediate whereas akinesia appears
later (4-5 min)
It does not create a significant rise in the IOP
Complications are chemosis and sub
conjunctival haemorrhage
TOPICAL
Advantages
• Absence of potential complications associated with the
orbital block:
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Retrobulbar hemorrhage
Perforation of the bulb
Retinal vascular occlusion
Diplopia
Ptosis
Systemic complications
Immediate functional recovery
No anxiety from the injection
Persistence of blinking
Greater safety during systemic therapy / pathology
(anticoagulants)
• Limited allergic reactions
• Saving in terms of time and cost
• Disadvantages
• more challenging owing to saccadic eye movements
during surgery
• Maximum anxiety to the patient
• Eye motility
• Relatively contra-indicated in complicated cases
(narrow pupil) and in patients affected by deafness
or dementia
TECHNIQUE
Sterile, preservative-free topical anesthesia such as
methylparaben-free 0.75% bupivacaine hydrochloride or
4 to 2% xylocaine should be used
Every attempt should be made to avoid applying the
drop directly onto the cornea, as this can result in
epithelial toxicity
Applica- tion of the topical anesthetic in a circurn-limbal
pattern anesthetizes the long ciliary nerves while
protecting the cornea
intravenous sedation can be a useful adjunct to topical
or intra- cameral anesthesia
One percent preservative free xylocaine is an excellent
adjunct to topical anesthesia
A 0.25- to 0.50-ml bolus may be injected into the AC
FACIAL BLOCKS
Van Lint's technique
• The needle is inserted 1cm posterior to the junction point between the
inferior and lateral orbit rim and penetrates as far as the periostium 1
mI of anesthetic is injected
• The needle is then directed towards the lower eyelid and 1 mI of
anesthetic is injected deep in the orbicular muscle
• The needle is then re-direct~d towards the upper eyelid and another 1
mI of local anesthetic is injected
O'Brien's technique
• The needle is introduced 1 cm anterior to the tragus until it comes into
contact with the periostium of the mandibular condyle that is easily
identified when the patient opens and closes his mouth
• 2-4 mI of anesthetic agent is introduced as the needle is withdrawn
Atkinson's technique
• The branches of the facial nerve are blocked on the zymgomatic arc by
injecting 5-10 mI of anesthetic agent
• The technique is not frequently used because of the high number of
failures
Nadbath and Rehman technique
• The block of facial nerve is achieved with the injection of local anesthesia
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where the main trunk of the nerve emerges from the stylomastoideal foramen
The injection site is located between the mastoid process and the posterior
edge of the mandibular branch
A short needle (12-16 mm) is used and between 2-4 mI of anesthetic agent is
injected
Associated with the highest risk of serious complications as rapid-onset
dysphagia, accumulation of secretions, laringo-spasm and distressed
respiration because of ipsilateral paralysis of the IX, X and XI cranial nerves
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