Local and topical anesthesia are now the norm for cataract surgery, with only 2% of patients requiring general anesthesia. Topical anesthesia involves applying local anesthetic eye drops. Retrobulbar and peribulbar blocks involve injecting local anesthetic behind or around the eye muscle cone. Sub-Tenon's block involves injecting local anesthetic into the space beneath the outer protective layer of the eye. While topical and local blocks provide anesthesia, general anesthesia allows for a quiet, immobile patient but is more expensive and risky.

1. Anesthesia for Cataract Surgery

2. • Local and topical techniques are now the
norm
• 2% of patients requiring general anesthesia

3. Local Anesthesia
• Minimal disruption for the patient
• Sedation may be useful (Standard fasting
times)
• Monitoring: ECG, pulse oximetry
• Supplemental oxygen

4. Local Anesthesia
• Topical anesthesia
• Retrobulbar block
• Peribulbar block
• Sub-Tenon's block

5. Topical anesthesia
• Oxybuprocaine (benoxinate) 0.4% : frequently
used
• Proparacaine (proxymetacaine) 0.5% is less
toxic to the corneal epithelium, shorter
duration of action (20 min)
• Other: including tetracaine (amethocaine)
0.5–1%, lidocaine 1–4% and bupivacaine 0.5–
0.75%, longer duration, but increased
associated corneal toxicity

6. Advantages
•No risk associated with needle insertion
•Reduced risk of periocular hemorrhage
•Functional vision is maintained; advantageous for uniocular patients
•Reduced postoperative diplopia and ptosis
Disadvantages
•An awake and talkative patient can be distracting for the surgeon
•No akinesia of the eye
•Less-effective anesthesia than sub-Tenon's block
•Increased risk of surgical complications. If difficulties or problems
occur anesthesia may be inadequate
•May be unsuitable for less-experienced surgeons

7. Adverse Effects of Topical Ocular Anesthetics
•Direct corneal effects – alteration of lacrimation and tear film stability
•Epithelial toxicity – healing has been shown to be delayed when an
epithelial defect occurs (lidocaine does not appear to affect healing)
•Endothelial toxicity – this occurs when penetrating trauma is present
and appears to be related to the preservative benzalkonium
•Systemic effects – lethal toxicity (this is only a problem with cocaine)
•Allergy and idiosyncratic reactions
Secondary Adverse Effects
•Surface keratopathy

8. • Topical anesthesia may be combined with
subconjunctival or, more commonly,
intracameral anesthesia to improve patient
comfort
• As visual perception is not lost
• Several studies showing inferior analgesia
compared to both peribulbar and sub-Tenon's
blocks, and an increase in surgical
complication rate

9. Retrobulbar Block
• Aim is to block the oculomotor nerves before
they enter the four rectus muscles by
depositing local anesthetic directly into the
posterior intraconal space
• Peribulbar block offers a safer

10. Advantages
•Reliable akinesia
•Onset of block is quicker than with peribulbar anesthesia
•Low volumes of anesthetic result in a lower intraorbital
tension and less chemosis than with peribulbar blocks
•Temporary loss of visual acuity occurs more reliably than for
peribulbar block
Disadvantages
•Risk of brainstem anesthesia – reason for the development
of the peribulbar block
•Risk of myotoxicity and globe perforation

12. • Clean the lower lid with the prep wipe.
• Ask an assistant to pull the upper lid upward to see if the block needle is
going through muscle, which will be indicated by movement of the globe.
• Palpate the inferior orbital margin. Feel the infraorbital notch,
approximately at the junction between the medial two thirds and the
lateral one third of the inferior orbital rim.
• Make a skin wheal immediately lateral to the notch using a small gauge
(30 gauge) needle and syringe.
• Advance the block needle straight down and perpendicular to the plane of
the face, until you encounter a distinct pop that indicates passage through
the orbital septum
• Angle the block needle 45 degrees medially and 45 degrees superiorly
toward the apex of the orbit until the second pop through the muscle
cone is felt
• Aspirate for blood.
• Inject 2 to 3 mL of the anesthetic solution.

13. Peribulbar Block
• instill local anesthetic outside the posterior
muscle cone
• avoid accidental injection into the optic nerve

14. Technique
• local anesthetic drops are applied to the cornea
• At the inferotemporal lower orbital margin a 25-
gauge, 25 mm needle is advanced parallel to the
plane of the orbital floor either transcutaneously
or transconjunctivally
• A degree of upwards and inwards angulation may
be needed once past the equator of the globe
• Local anesthetic (4–6 mL) is injected at a depth
of about 20 mm from the inferior orbital rim

16. Complications
-Most serious complications of peribulbar
anesthesia relate to the use of sharp needles.
•Globe perforation/penetration
•Retrobulbar hemorrhage
•Extraocular myotoxicity

17. Sub-Tenon's Block
• Tenon's capsule is a facial sheath, a thin
membrane enveloping the eyeball and
separating it from orbital fat

18. Technique
• The conjunctiva is anesthetized first with a topical local
anesthetic of choice
• The commonest approach is via the infranasal quadrant
• The eye is cleaned with iodine 5% and the patient asked to
look upwards and outwards
• Aseptically, the conjunctiva and Tenon's capsule are held 3–
5 mm from the limbus using non-toothed Moorfields
forceps
• A small incision is made through these layers using blunt-tipped,
sprung Westcott scissors exposing the sclera
• A cannula is then advanced into the sub-Tenon space and
around the globe

21. General Anesthesia
• unsuitable for local anesthesia
• method of choice for babies, children, and the
uncooperative

22. Advantages
•Patient comfort
•Ideal operating conditions – a quiet, immobile patient and soft eye
•Allows for rapid alterations in intraocular pressure if required
•No risk of complications associated with local anesthetic blocks
•No residual paralysis of the eye when the patient is awake
•Bilateral surgery can be performed
•Better conditions for teaching
Disadvantages
•Slower turnaround times
•More expensive
•Greater risk in frail elderly
•Greater physiological disruption for patient

23. • Ophthalmology , Fourth Edition, Myron Yanoff,
and Jay S. Duker