The real voyage of discovery consists not in seeking new landscapes, but in having new eyes.
Introduction
Cataract surgery is a sizeable proportion of all operations performed in elderly patients and is the most common office-based procedure in Europe (Eurostat 2015). In the US, more than 2 million cataracts are extracted annually, in Italy there are 500,000 cases a year, which represent 83% of the total ophthalmic operations. Office-based operations are considered low-risk procedures, but in the case of cataract, most of the patients are elderly, ASA risk ≥ 3, and at great risk of perioperative complications. (Gayer and Zuleta 2008). Strategies for preoperative risk assessment and intraoperative anesthesia care are far from being univocally evaluated and homogeneously implemented worldwide, and organizational approaches can substantially differ from country to country and from institution to institution.
It has been argued that cataract surgery (CS) is one of the most cost-effective procedures in medicine, compared to other interventions across medical specialties (Busbee et al. 2003). A recent review (Lamoreaux et al. 2011) shows that the impact of CS on health-related quality of life is overwhelmingly compelling. Resulting in significant vision improvement, CS is translated to considerable gains in real life daily activities and several emotional and social components.
A cataract is defined as a clouding of the normally clear crystalline lens of the eye. Nuclear cataract is the most common type of age-related cataract leading to surgery. Both are caused by central opacities in the lens and have a substantial genetic component. Age, female sex and smoking seem to be significant risk factors. Cataract extraction is usually carried out by an ultrasound emulsification. In this technique, an ultrasonic probe, inserted into the eye, emulsifies the lens by vibration of the instrument tip. The emulsified lens material is vacuumed out of the eye, leaving the posterior capsule in place. At this point the extracted lens is usually replaced with a synthetic intraocular lens (IOL; Solomon and Donnenfeld 2003). The operation is usually performed on an office-based or outpatient basis.
Preoperative Evaluation
General Considerations
Elderly patients often present with associated conditions, have less physiologic reserve and are more compromised in their ability to handle stress. About one-third have four or more chronic conditions (Christmas et al. 2006). Some of them suffer from cognitive disorders and may offer limited compliance to surgical manipulation. Frail subjects are at greatest perioperative risk, even from minor procedures (see Chapter 2).
In addition, ophthalmic surgery requires extreme delicacy of surgical movements, and presents difficulties and inherent risks (extreme vagal reflectivity, difficult access to the patient’s mouth, need to cover the patient’s face, possible panic reactions and claustrophobia, inappropriate patient movement during surgery, etc.), that cannot be quantified with either the duration or the invasiveness of surgery. A procedure started under topical anesthesia may require a shift toward sedation or even general anesthesia. Thus, eye surgery in the elderly is not always plain and low risk (Raczynska et al. 2016), and the assumption that routine preoperative anesthesia assessment and intraoperative care is not needed should not be blindly followed.
No clear guidelines are available for when and how preoperative assessment should be performed in older patients undergoing cataract surgery, and routine anesthesia consultation often represents a substantial discretionary service (Thilen et al. 2014). Ophthalmic surgery, for the particular anatomy of the eyeball, requires extreme delicacy of surgical movements, and presents difficulties and inherent risks (extreme vagal reflectivity, difficult access to the patient’s mouth, need to cover the patient’s face, which can trigger panic reactions and claustrophobia, risk of inappropriate patient movement during surgery, etc.).
Some clinical centers and unfortunately some papers, in order to optimize the cost-effectiveness, propose performing the operation without an anesthesiologist, with only the availability of a MET (medical emergency team) and ignoring venous access, preoperative fasting and intraoperative monitoring (Koolwijk et al. 2015). In Italy, the Italian Opthalmologists Society (SOI) together with other Italian societies, disagree with this approach and underline the importance of the anesthesiologist during ambulatory surgeries in order to ensure patient safety (Il Sole 24 Ore, 2015).
The Royal College of Ophthalmologists Commission Guide on Cataract Surgery (2015) reports that the cataract pathway should cater for the needs of a minority of patients whose needs should be identified in order to secure the best achievable outcome, to reduce the risk of complications or to make the experience of surgery tolerable. The same guide also reports that approximately 5% of patients require general anesthesia to undergo the procedure and that these patients require formal preoperative anesthesia consultation. However no mention is made of how to manage possible cardiac or respiratory intra- and/or postoperative complications or agitation, which would require anesthesia care.
A recent Canadian study (Jastrzekski et al. 2016) evaluated the usefulness of a preoperative self assessment health questionnaire that allowed classification of patients into low-risk subjects not requiring a preoperative assessment and high-risk subjects requiring this assessment. This graded system resulted in no major complications and a low rate of minor complications and proved to save time and resources by eliminating unnecessary consultation.
Should Laboratory Tests be Performed Before Cataract Surgery?
Many papers and reviews have shown that routine preoperative tests do not influence outcome or reduce adverse events, and do not increase the safety of cataract surgery (Schein et al. 2000). The ASA (American Society of Anesthesiologists) task force on preoperative evaluation also concluded that routine preoperative testing does not influence outcome. Laboratory tests should be requested on the basis of a thorough evaluation by a physician (Roizen 2000).
A clinical history will identify patient characteristics that may warrant intervention and management before elective eye surgery. Both the history and the physical status may dictate the need for laboratory data (see Chapter 8).
Preoperative Assessment in Practice
The main purpose of a preoperative assessment is to identify patients suitable for ambulatory surgery, as well as to determine the risks associated with a detrimental outcome. The surgeon is the first physician who screens the patient. Anesthesiologists often meet the patient on the day of surgery or interview patients by telephone, the day before. As elderly patients have many comorbidities, the surgeon should address some of them, with the most frail in particular, to the anesthesiologist in order to reduce cancellations on the day of surgery, as well as to avoid perioperative complications and improve the efficiency of the ambulatory facilities (Holt et al. 2007).
In order to help surgeons to identify patients with severe diseases (ASA class ≥3), there are screening questionnaires available to evaluate their physical status. At our Institution (Catholic University of Sacred Heart, “A. Gemelli” Teaching Hospital – Rome) at the first ophthalmological visit surgeons submit a screening questionnaire to the patient assessing physical status and pass it to the anesthesiologist who will take care of the patient (Figure 29.1).
Figure 29.1 Screening questionnaire in use at the Sacred Heart Catholic University “A. Gemelli” Teaching Hospital – Rome.
As always, the anesthetist should evaluate habits, allergies, past operations, cardiovascular status, hypertension, anticoagulation status, pulmonary diseases, renal and hepatic disorders, neurological status, endocrine dysfunction, current medications and check for difficult airways. The responsibility of the anesthesiologist is to ensure that the patient is in optimal clinical condition before undergoing surgery (Pasternac 2003).
Management of Specific Conditions
Chronic Medical Conditions
Chronic medical conditions such as congestive heart failure or chronic obstructive pulmonary disease, patients with a recent attack of angina, uncontrolled arrhythmias, recent ischemia or infarction can be scheduled for ambulatory surgery after the optimization of therapy and clinical status. A similar approach must also be used for patients with a recent cerebrovascular attack or exacerbation of a chronic cerebral disorder.
Uncontrolled hypertension presents a significant cardiovascular risk and blood pressure must be decreased to acceptable levels (Chobanian et al. 2003). Blood pressure of 200/110 mmHg or more before the operation requires adjustment of therapy and the postponement of elective surgery. Topical phenylephrine, frequently used in ophthalmic surgery, can precipitate marked hypertension with potentially devastating consequences. Ophthalmologists should be advised to limit concentration, dose and frequency of application of phenylephrine drops, mostly in elderly patients with poorly controlled hypertension (Fraunfelder et al. 2002). Severe valvular diseases are active cardiac conditions that may require delay or cancellation of elective surgery until the valvular lesion has been fully evaluated and treated.
Many patients have implantable cardiac defibrillators (ICDs), but in ophthalmic surgery the risk for electromagnetic interference causing device discharge is negligible (Bayes 2006).
Elderly patients are more vulnerable to postoperative pulmonary complications. The risk increases with general anesthesia, but most cataract surgery can be performed under local or topical anesthesia, thus making this risk negligible. Nevertheless, the risk of aspiration should be carefully prevented, mostly in patients with neurological disease (Parkinsons, stroke, sleep apnea, neuromuscular disorders) where respiratory muscle dysfunction and impaired lingual control of swallowing can be present (Oliveira et al. 2004).
Renal insufficiency is considered an independent predictor of postoperative cardiac and pulmonary complications. End-stage renal disease patients undergoing elective eye surgery need to coordinate their surgical procedure with their dialysis schedule, to minimize any fluid imbalances and mitigate electrolyte abnormalities.
Benign prostatic hypertrophy treated with α1-receptor antagonists is associated with “floppy iris syndrome,” characterized by compromised iris muscle tone and inadequate pupil dilation, limiting the ophthalmologist’s surgical access.
Management of Chronic Antiplatelet/Anticoagulant Drugs
Many geriatric ophthalmic patients require chronic antiplatelet or anticoagulant therapy because of greater risks of myocardial infarction, stroke, deep venous thrombosis or pulmonary embolism. It was believed for many years that those patients might be at higher risk for complications during ocular surgery. There is a risk of thromboembolic events if antiplatelet or anticoagulation treatment is suspended; however, continuation of therapy may be associated with serious perioperative bleeding. Thus, different strategies were proposed in the past to prevent these complications, including discontinuation of anticoagulants, dose reduction or low-molecular-weight heparin replacement. The phacoemulsification technique with implantation of foldable intraocular lenses (IOLs) through avascular clear corneal incisions has a low risk for bleeding: the current thinking is to continue anticoagulants and antiplatelet treatment because the increased risk of thromboembolism outweighs the minor ocular hemorrhages that can happen (Grzybowski et al. 2015). Otherwise, there is no clear consensus about discontinuation of antiplatelet and anticoagulant therapy in vitreo-retinal surgery because it is not clear if the risk of bleeding is increased or not. In this case, the decision to maintain, reduce or discontinue anticoagulation preoperatively should involve communication with patient, physician prescribing the anticoagulant/antiplatelet therapy, ophthalmologist and anesthesiologist to evaluate risks and benefits associated with each strategy (Oh et al. 2011, Passemard et al. 2012).
Patient Positioning on the Operating Table
Cataract surgery can become more complex when the patient cannot be positioned supine on the operating table because of pulmonary disease, congestive heart failure, obesity, myotonic dystrophy or Ménière’s syndrome. With creative modifications to normal positioning, successful phacoemulsification can be executed under topical anesthesia, ensuring patient safety and surgeon comfort (Rogers and Goins 2010). Some papers present cases of extreme positioning, e.g., “face-to-face” positioning with the patient seated upright in his wheelchair (Pajaujis et al. 2013).
Anesthesia, Intraoperative Management and Monitoring
Cataract surgery is usually performed under topical or local anesthesia when allowed by the health condition of the patient, while general anesthesia is reserved only for particular cases. Decisions on the anesthesia technique largely depend on the condition of the patient, the expected duration of the operation and preferences of the surgeon.
Topical Anesthesia
Topical anesthesia is performed using local anesthetic drops, gels or sponges applied to the conjunctival sac while pressing lightly to prevent loss from the nasolacrimal duct (Page and Fraunfelder 2009).
Mepivacaine, lidocaine, ossibuprocaine, bupivacaine and ropivacaine are examples of commercially available local anesthetics. It has been demonstrated that intraocular pressure (IOP) can decrease after instillation (Almubrad and Ogbuehi 2007). Topical anesthesia may be insufficient to obtain complete analgesia. Supplemental blocks may cause sensory blockade of the iris and ciliary body and increase comfort during intraocular lens placement.
Retro-bulbar Block (RBB)
In the past, RBB was widely accepted as a regional technique for ocular anesthesia. The RBB method consists of injecting local anesthetics into connective tissue inside the extra-ocular muscle cone behind the globe. Insertion of the needle is onto the inferior orbital rime, two-thirds lateral from the inner canthus, since it is free from vascular and neural components. The eye must be kept in the neutral position, the globe may be displaced up and nasally with the finger of the free hand. The needle (27–30 G, 32 mm) is advanced directly, then angulated about 10° medially and superiorly. It is generally advisable not to introduce the needle more than 25 mm in order to prevent complications.
A local anesthetic volume of 2–4 ml is usually sufficient, but when necessary it may be increased. Both analgesia and akinesia of the globe are higher after RBB in comparison with other techniques. Ulterior blocks are requested for analgesia of eye annexes. Rare, but serious, local and systemic complications, including globe perforation, ipsilateral or contralateral vision loss, palsies and cardiac or respiratory arrest, can occur. This has led to progressive abandonment of this technique in favor of peribulbar block and topical anesthesia.
Peribulbar Block (PB)
PB is a more recent technique and is widely employed. It consists of the injection of local anesthetic externally to the muscle cone. The needle entry point is the same as for the RBB (Figure 29.2). The needle (26 G, 25 mm) is introduced directly and is shorter than for RBB. A larger volume of local anesthetic is required and the onset is longer compared with the previous technique. The complication rates for the PB is lower than that reported with other techniques.
Figure 29.2 Peribulbar block: needle entry point.
The incidence of pain during the injection in both techniques is high: analgo-sedation with remifentanil slow bolus (0.5–1 mcg/kg over 2 minutes) is useful to obtain an intense, but short analgesia while the patient remains awake and cooperative (Johnson et al. 2002).
Monitored Anesthesia Care (MAC)
MAC is a specific anesthesia technique in which the anesthesiologist is requested to participate in the care of a patient undergoing a diagnostic or therapeutic procedure. Cataract surgery performed under topical or regional anesthesia and light sedation is a classic example of MAC. The goal is to provide analgesia, amnesia and sedation without compromising protective airway reflexes.
An ideal sedative drug should have a rapid onset and a short duration of action to ensure quick awakening and home readiness. Common medications used for sedation in ophthalmic procedures can be classified into three categories: benzodiazepines (midazolam), opioids (fentanyl, remifentanil) and hypnotic agents (propofol, ketamine). Various combinations of these drugs have been used in tandem (Lin and Tao 2014). Elderly patients require careful titration of lower doses of sedatives, hypnotics and opioids because the drugs can frequently produce oversedation, apnea, hypoxia, hypotension and bradycardia. A sedation level that allows communication with the patient is usually appropriate, while heavy sedation is not suitable: indeed the patient could awaken suddenly and compromise surgery course and outcome.
The ASA have determined the minimum requirements of monitoring during MAC including ECG, pulse oximetry, non-invasive blood pressure, temperature, end-tidal CO2 and respiratory rate monitoring. Oxygen should be administered through nasal cannulae. Measures for claustrophobic patients should include raising the sterile drapes to improve patient comfort.
General Anesthesia (GA)
GA offers motionless surgical conditions including ocular akinesia with decreased intraocular pressure. GA is reserved for particular cases and may be needed in neurological diseases, intractable claustrophobia and in patients with difficulty keeping a supine position. Nowadays, thanks to short-acting drugs (such as desflurane and remifentanil) balanced anesthesia is the best GA technique, as it allows deep anesthesia until the end of the operation and a rapid recovery. It is also the best technique in high-risk patients. Total Intravenous Anesthesia-Target Controlled Infusion (TIVA-TCI) allows controlled hypotension and shows the best control of IOP.
Postoperative Care and Discharge
Discharge planning and postoperative patient instructions should begin preoperatively, preferably with the patient’s family members or friends. Diminished risk of developing postoperative complications, reduced need for pain medication and improved patient satisfaction are the benefits of early preoperative education.
On the day of surgery the patient must always be accompanied by family members or friends because of the impossibility of seeing with both eyes at the time of discharge.
The criteria to allow a patient’s hospital discharge are: stable vital signs, well-managed pain, ability to tolerate fluids and food intake, restored preoperative mental ability, minimal nausea and vomiting (PONV) and ability to walk without dizziness (Dunn 1998).
Pain can be managed with NSAID drugs, acetaminophen and, in more painful surgeries, opioids (tramadol, morphine). The best timing for drugs to prevent PONV is the administration of desametasone before starting surgical maneuvers and ondansetron at the end of surgery. Vomiting, sneezing, straining or any activity that may produce the Valsalva maneuver may increase IOP, which can damage the operated eye. To prevent pressure increasing in the operated eye, the patient should lie on their back or on the non-operated side. After vitreo-retinal surgery, the patient may require special positioning (Spires 1996).
Nowadays ophthalmic surgery, thanks to new technologies and techniques, is easier than in the past and can be mostly considered an office-based practice. Clear instructions at discharge are essential and help to improve surgical outcome and patient satisfaction.
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