Cataract Surgery – Procedures

What the Anesthesiologist Should Know before the Operative Procedure

Cataract surgery is one of the most common surgical procedures in the world with over 1,000,000 cataract operations performed annually in America alone. The World Health Organization estimated more than 10 million cataract operations were performed worldwide annually at the end of the 20th century. Cataract surgery has a proven history of success with a very low complication rate.

A cataract is simply an opacity in the lens of the eye. These opacities may form due to a number of causes, but the most common is age. Age-related cataracts may be due to changes in the metabolic structure of the crystalline fibers of the lens. This leads to the clumping of the proteins in the lens or to a discoloration of the lens. This can cause blurry or tinted vision, which can lead to inability to perform daily activities. Cataracts typically form very slowly. Cataracts can also be congenital in infants or caused by trauma or other illnesses like glaucoma or diabetes. There is some evidence that hormone replacement therapy may increase the incidence of cataract formation in postmenopausal women.

Possible risk factors for cataract formation

• Age

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• Radiation

• Diabetes

• Smoking

• Alcohol use

• Lead exposure

• Glaucoma

• Trauma

• Congenital

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

N/A

2. Preoperative evaluation

There is nothing specific about the preoperative evaluation that needs to be completed prior to cataract surgery. In general, patients undergoing cataract surgery are elderly and have all of the complicating factors associated with the geriatric population.

3. What are the implications of co-existing disease on perioperative care?

Cataract surgery is considered a very low-risk procedure with minimal (not zero) impact typically on cardiac or pulmonary physiology. Some eye drop medications containing vasoactive substances (e.g., Phenylephrine), designed to dilate the pupil in preparation for surgery, can transiently worsen a pre-existing systemic condition like hypertension or arrhythmias.

b. Cardiovascular system:

N/A

c. Pulmonary:

N/A

d. Renal-GI:

N/A

e. Neurologic:

N/A

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient’s medications and how should they be managed in the perioperative period?

Antiplatelet and anticoagulant medications

In 2009, Benzimra et al retrospectively reviewed the data on more than 50,000 patients having eye surgery and published their findings in the journal Eye. They found that although patients on therapeutic levels of Warfarin (about 2500 patients) and Plavix (about 1000 patients) had a higher risk of non-threatening bleeding (e.g., lid and conjunctival hematoma) after eye blocks, none of the groups (including the patients on Aspirin – about 12,500 patients) had any sight threatening bleeding from these three drugs. There is currently no data to support the safety of “injection anesthesia” (Retrobulbar, Peribulbar or Subtenon anesthesia) in patients taking Dabigatran (Pradaxa), and therefore the current recommendations are to withhold this drug for 2-5 days prior to surgery.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

N/A

i. What should be recommended with regard to continuation of medications taken chronically?

N/A

j. How to modify care for patients with known allergies

N/A

k. Latex allergy – If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

N/A

l. Does the patient have any antibiotic allergies – Common antibiotic allergies and alternative antibiotics

N/A

m. Does the patient have a history of allergy to anesthesia?

N/A

5. What laboratory tests should be obtained and has everything been reviewed?

N/A

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Anesthesia for cataract surgery

Although general anesthesia was introduced for cataract surgery as early as 1846, it was not popular among ophthalmologists. This was due to the fact that patients died from the anesthesia for a procedure felt by the surgeon to be relatively simple. For the four decades from the 1840s to the 1880s, many ophthalmologists preferred to operate with patients in restraints rather than use general anesthesia.

The major advance in anesthesia for cataract surgery occurred in 1884 when Koller demonstrated and documented the use of cocaine as a topical anesthetic for “painless” eye surgery. The use of cocaine did not eliminate pain for patients and many would squint or move their eye or blink making it difficult for the surgeon. Therefore, many patients still required heavy sedation to remain comfortable for the procedure.

Although some surgeons had used injection of cocaine into the orbit in the 19th century, it was fraught with complications and was relatively unused until the 1920s when Lowenstein and Duverger showed excellent conditions for cataract surgery (and enucleations) could be achieved with regional orbital blocks with local anesthesia. Regional anesthesia for cataract surgery exploded in use in the 1950s in the US. Atkinson was the first to describe the use of the retrobulbar block to produce akinesia and anesthesia for cataract removal. Today, regional anesthesia is overwhelmingly preferred and utilized for cataract surgery.

Anesthetic goals for cataract surgery

• Akinesia

• Analgesia

• Minimal bleeding

• Avoiding oculocardiac reflex

• Minimal anxiety

Although traditionally, retrobulbar block was used to accomplish regional anesthesia for cataract surgery, peribulbar block has become more popular since the 1990s because of its better safety profile. And even more recently, many surgeons have been utilizing topical anesthesia for patients. Topical anesthesia is appropriate for cooperative patients and where the surgeon does not require akinesia of the eye. Subtenon blocks have gained popularity in the UK and Australia, and are now the dominant anesthesia used in Europe for cataract surgery, but are relatively infrequently used in America.

Retro/peribulbar anesthesia

Traditional concepts of ocular anatomy held that the four rectus muscles and its fibrous sheaths enveloped the eye posteriorly and formed an “orbital cone.” The goal of the retrobulbar block was to introduce a needle into this cone to deposit local anesthetic behind the eye. More recent studies in cadavers have shown that there is not a complete sheath or cone behind the eye, and that there are multiple septations and gaps in the rectal muscle sheath. Nevertheless, the retrobulbar block provides rapid and complete anesthesia of the eye with small amounts (2-3 mL) of local anesthesia. The retrobulbar needle is typically one and one-fourth to one and three-eighths inches in length in order to reach behind the globe. These blocks are typically performed by ophthalmologists when they need complete akinesia of the eye and/or may have concern of increasing IOP. Often times, retrobulbar blocks are utilized for retinal surgery.

In contrast, the peribulbar block typically utilizes a significantly shorter needle (length typically 7/8 inch) and deposits the local anesthetic outside of this muscle cone. Local anesthetic deposited in this extraconal space then diffuses toward the optic nerve to establish anesthesia. Peribulbar blocks typically require larger volumes of local anesthetic (we typically utilize 6-7 mL) and will take longer to develop anesthesia. Additionally, peribulbar blocks typically reach the branch of the facial nerve that enervates the orbicularis oculi so that lid akinesia is also achieved. Retrobulbar blocks often do not provide lid akinesia and another needle entry will be required if lid akinesia is required.

The peribulbar block has been shown to have fewer complications, at least theoretically, due to the fact that the needle tip cannot reach the vital intraorbital contents or brain. It is important to remember that it is still possible to penetrate the globe with either type of needle and careful, meticulous technique is essential for minimizing complications.

A Cochrane report on anesthesia for cataract surgery from 2015 showed there was no evidence of any difference between peribulbar versus retrobulbar block in complete akinesia or the need for further injections of local anesthetic. Conjunctival chemosis was more likely with peribulbar anesthesia and lid hematoma was more common after retrobulbar block. Retrobulbar hemorrhage was uncommon and severe local or systemic complications were rare for both types of block.

Possible complications

• Superficial hemorrhage (periorbital hematoma)

• Retrobulbar hemorrhage (can lead to glaucoma or increased IOP)

• Chemosis (anterior spreading of local anesthesia solution leading to ballooning of the conjunctiva)

• Orbital cellulitis (from worsening pre-existing infection or new onset infection after performing the eye block)

• Trauma to extraocular muscles (can lead to postoperative strabismus, diplopia)

• Globe penetration (can lead to permanent loss of vision, retinal detachment)

• Oculocardiac reflex stimulation (can lead to symptomatic hypotension or cardiac arrest)

• Central spread (penetrating optic nerve sheath)—leading to hypotension, respiratory failure, loss of consciousness

• Intravenous/arterial injection of local anesthetic—systemic local anesthetic toxicity

• Blindness

• Death

Table I displays the incidence of utilization of different anesthetic techniques for cataract surgery in the UK and the relative incidence of serious complications. Results based on a survey of NHS ophthalmologists.