Ophthalmology presentation on anaesthesia for cataract surgery

1. Type of anaesthesia for cataract
surgery
Roll no 0954

2. Anaesthesia
Local
Surface Regional
General

3. Local Anaesthesia
• Surgery can be undertaken as a day-care procedure
• Entails little risk and is less dependent upon patient’s
general health
• Does not require sophisticated equipment
• Easy to perform, has got rapid onset of action
• Provides a low intraocular pressure with dilated pupil.
• Can be used to reduce intraocular pressure and
vitreous volume when necessary
• Economical

4. Local anaesthetics
• Temporary loss of sensation, analgesia and/or function (akinesia)
• Protein bound receptors located near sodium channel
• Anaesthesia causes ↓ depolarisation of nerve membrane
Local anaesthetic Onset of action Duration Use(concentration)
Benoxinate 6-20 seconds 15 minutes Topical(0.4%)
Proparacaine 15-30 seconds 15-20 minutes Topical(0.5%)
Amethocaine 10-25 seconds 10-20 minutes Topical(0.5-1%)
Lignocaine (3
mg/kg max)
10-35 seconds
5-10 minutes
15-20 minutes
30-60 minutes
Topical(4%)
Infiltration(0.5%-
1%)
Bupivacaine (2
mg/kg max)
Moderate 75-90 minutes Infiltration(0.25-
0.75%)
Ropivacaine Moderate 1.5-6 hours Infiltration(1%)
Adrenaline-to prolong duration, reduce bleeding Propofal and midazolam- anxiety, amnesia

5. Surface (Topical) anaesthesia
•Phacoemulsification in cooperative patients
•Prior to regional blocks for intraocular surgery
•Usually a drop of anaesthetic solution instilled 4 times after every 4 minutes is
sufficient to produce conjunctival and corneal anaesthesia.
•Lignocaine 4 %
•Amethocaine 1%
•Benoxinate
0.4%
•Cocaine
,Paracaine
Oxybuprocaine or benoxinate: bactericidal
properties
Available mixed with flourescein for applanation pressure recordings

6. REGIONAL ANAESTHESIA
Nerve
blocks
Peribulbar
Parabulbar or sub-
Tenon
Intracameral
anaesthesia
Facial block
Frontal block
Retrobulbar
Local
infilteration

7. Peribulbar block
• This technique described in 1986 by Davis and Mandel
• Almost replaced the time-tested combination of retrobulbar and facial
blocks
• In a 10 ml syringe-
5 ml bupivacaine 0.75% Provides early onset of
action
5 ml lignocaine 2% with
1:20000 adrenaline
Prolonged efficacy
75 units hyaluronidase Permits diffusion into orbit
•25 gauge 2.5 cm disposable needle is attached to the syringe
•Topical anaesthesia is instilled into conjuctival sac
•Patient placed in supine position and asked to look steadily
straight ahead

8. • Needle is inserted transconjuctivally
or transcutaneously at junction of
middle 2/3 and lateral 1/3 of lower
lid adjacent and parallel to orbital
floor for about 2.5 cm
• Gentle aspiration is performed and 5
ml of mixture is injected into lateral
adipose tissue of orbit
•Pressure is applied to the site for a couple of minutes
•Just medial to middle canthus same needle is inserted to
2.5 cm and 3 ml is injected
•Pressure is applied for couple of minutes
•Or, inferomedial to supraorbital notch, more complications.
Honan pressure cuff applied for 15 minutes

9. • Anaesthesia and analgesia begin in 5 minutes
• Most patients- takes 15 minutes
• Supplemental injections:
 Inferiorly- persisting inferolateral movements
 Superiorly-residual superior or medial movements

10. Complications
• Chemosis
• Periorbital ecchymoses
• Penetration of globe- more in myopes with larger
eyes and staphylomas
• Oculocardiac reflex
• Retrobulbar hemorrhage
• Inadvertent intravascular or intrathecal injection
• Anaphylactic shock

11. Retrobulbar block• introduced by Herman Knapp in 1884.
•22 gauge 3.5 cm long needle is used to enter
transcutaneously at junction of middle and lateral
thirds of lower orbital margin
• It is first directed straight backwards for about 15
mm
• then angled upwards and medially towards the
apex of the orbit, up to a depth of 2.5 to 3 cm.
•As needle pierces the intermuscular septum
between lateral and inferior rectus muscles, the
feel is altered.
•After aspiration, 2 -4 ml of anaesthetic solution is
injected into the muscle cone behind the eyeball

12. (2% xylocaine with added hyaluronidase 5 IU/ml and with or
without adrenaline one in one lac)

13. • Retrobulbar block anaesthetizes the ciliary nerves, ciliary ganglion and
third and sixth cranial nerves thus producing globe akinesia (better
than peribulbar), anaesthesia and analgesia.
• The superior oblique muscle is not usually paralyzed as the fourth
cranial nerve is outside the muscle cone.
• Needs an additional facial block

14. Complications
• retrobulbar haemorrhage
• globe perforation
• optic nerve injury
• extraocular muscle palsies.
• amaurosis
•Oculocardiac reflex
•Anaphylactic shock

16. Parabulbar / sub-Tenon
block• Conjunctival incision 2-3 mm is made halfway between inferior limbus and fornix
to open into sub-Tenon space
• A blunt cannula or needle is used to inject anesthetic into posterior sub-Tenon
space, bathing the nerves and muscles within the cone
•Thought to
completely avoid
vascular and optic
nerve injury
•Low volumes of
anaesthetic required
•Better anesthesia to
iris and anterior
segment

17. Complications
• Chemosis
• Subconjunctival hemorrhage
• Penetration of globe
• Oculocardiac reflex
• Anaphylactic shock

18. Facial block
• To block the facial nerve which supplies the orbicularis
oculi muscle, so that patient cannot squeeze the
eyelids.
• Necessary with retrobulbar block
• 1. van Lint’s block:
• Blocks the terminal branches of the facial nerve
• produces localized akinesia of the orbicularis oculi without
associated facial paralysis.
• 22 gauge 3.5 cm needle is inserted subutaneously outside the
lateral canthus and advanced upwards towards the brow, and
downwards towards the infraorbital foramen, injecting along
both paths

19. 2. O’Brien’s block.
• facial nerve is blocked near the condyloid process of mandible.
• The condyle is located 1 cm anterior to the tragus. It is easily
palpated if thepatient is asked to open and close the mouth
with the operator’s index finger located across the neck of the
mandible.
• At this point the needle is inserted until contact is made with
the periosteum and then 4 to 6 ml of local anaesthetic is
injected while the needle is withdrawn
• Pain at the injection site and unwanted facial paralysis.

20. • 3. Nadbath block:
• the facial nerve is
blocked as it leaves the
skull through the
stylomastoid foramen
• Painful
• 4. Atkinson’s block:
• In it superior branches
are blocked
• Anaesthetic injected at
the inferior margin of
the zygomatic bone.

21. Complications
• Bruising
• Full hemifacial palsy-stylomastoid foramen
• 9, 10 nerves :Dysphagia, respiratory difficulty

22. Intracameral anaesthesia
• Lignocaine 1% without preservative or
adrenaline
• Provides only anaesthesia
• With topical anaesthesia
• For phacoemulsification

23. GENERAL ANAESTHESIA
Indications
• infants and children
• anxious,unco-operative and
psychiatric patients
• those suffering from dementia or
Alzheimer disease,
• perforating ocular injuries, major
operations like exenteration
• the patients willing for operation
under general anaesthesia.

24. • In perforating injuries and other ocular
emergency cases, use of suxamethonium
should always be preferred over non-
depolarizing relaxants
•use of relaxants, endotracheal intubation and
controlled respiration is preferred.
• it must be ensured that patient does not
develop carbon dioxide retention.
•When this occurs, choroid swells to many times
its normal value and ocular contents prolapse as
soon as the eye is opened.