This chapter covers general considerations for ophthalmologic procedures in children, specific anesthetic considerations for the more commonly performed pediatric ophthalmologic procedures, and several unique anesthetic complications that occur in pediatric ophthalmologic procedures.
Although the vast majority of children presenting for surgery on the eye are healthy, some ophthalmologic conditions are accompanied by coexisting morbidities. The majority of infants presenting for cataract surgery in the newborn period do not have coexisting diseases, but a variety of pediatric syndromes include cataracts in the constellation of anomalies. Some examples include intrauterine viral infection (e.g., rubella or toxoplasmosis) and metabolic disorders such as Lowe syndrome (developmental delay, hypotonia, and renal dysfunction). Infants with congenital glaucoma are less likely than those with cataracts to have coexisting abnormalities. Infants with retinopathy of prematurity (RoP) who present for laser photocoagulation will often have multisystem abnormalities associated with extreme prematurity, and they should be thoroughly evaluated preoperatively. Some children with strabismus may have a myopathic disease.
Preoperative Considerations
For children without traumatic disorders of the eye, age-appropriate anxiolytic premedication is indicated. If the child has an intravenous cathether, midazolam should be titrated to the child’s comfort. In the absence of intravenous access, oral midazolam 0.5 mg/kg (max 10 mg) can be administered.
Procedural Considerations
The major anesthetic implication for ophthalmologic procedures is the avoidance of factors that acutely increase intraocular pressure (IOP), especially in cases of ocular trauma where the integrity of the eye contents is at risk.
Normal IOP in children ranges from 10 to 21 mm Hg. Acute increases of IOP during intraocular surgery can cause extrusion of the vitreous humor, lens prolapse, and/or hemorrhage into the eye ( Table 27.1 ).
| FACTORS INCREASING IOP |
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| FACTORS DECREASING IOP |
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Anesthesia providers should be familiar with the types of topical ophthalmic medications used in the perioperative period and the possible related systemic effects ( Table 27.2 ).
| Medication | Concentration and Dose | Ocular Effects | Possible Systemic Effects |
|---|---|---|---|
| Phenylephrine HCI | 2.5%; 1–2 drops in each eye | Preoperative mydriatic: dilates the pupil and constricts the blood vessels of the eye | Hypertension and reflex bradycardia |
| Cyclopentolate HCI | 0.5%–1%; 1 drop in each eye every 5 minutes (2 doses) | Preoperative cycloplegic: dilates the pupil and prevents lens accommodation | Usually none |
Anesthetic Plan
Unless the child has significant comorbidities, standard monitors are sufficient for virtually all eye surgeries. Fluid and blood losses are minimal. Hypothermia does not usually occur, except in the smallest infants. In fact, in most cases, because most of the child’s body is covered, their temperature tends to rise by the end of the procedure. Most intravenous and inhaled agents will tend to lower IOP (in a dose-dependent manner), so they can safely be used for induction and maintenance of general anesthesia (see Table 27.1 ). There are, however, some notable exceptions. Ketamine has been shown to acutely increase IOP in children. Administration of intramuscular ketamine is associated with both increased and decreased IOP, depending on the study one reads. Nevertheless, other associated effects of ketamine such as blepharospasm and nystagmus render it undesirable during eye procedures. If intramuscular ketamine is required for an older uncooperative child who requires emergency eye surgery, then its advantages probably outweigh the risks; this decision should be made on a case-by-case basis. Administration of etomidate has been shown to reduce IOP, but in one case it was associated with loss of eye contents from a ruptured globe as a result of myoclonic movements that occurred after its administration. Nitrous oxide (N 2 O) should be avoided if the ophthalmologist plans to inject sulfur hexafluoride gas, because N 2 O can then diffuse into the eye and increase IOP. This also applies if sulfur hexafluoride gas was injected into the eye in the previous 2 weeks.
Succinylcholine causes a 7 to 12 mm Hg increase in IOP that lasts 5 to 6 minutes. The mechanism of this phenomenon is controversial: originally, it was thought that succinylcholine uniquely caused contraction of the extraocular muscles, but one study demonstrated an increase in IOP in an in vitro isolated eye model without extraocular muscles attached. Different induction regimens have been reported to attenuate the effects of succinylcholine before tracheal intubation, but none consistently decreases IOP. Therefore, most pediatric anesthesiologists prefer to avoid succinylcholine in open globe procedures, unless its benefit (i.e., rapid paralysis) clearly outweighs its risks. In other words, one would have to believe that the risk for pulmonary aspiration is sufficiently high so as to risk the loss of sight that would occur if succinylcholine caused extrusion of eye contents. On the other hand, proponents of succinylcholine cite the fact that there are no reported cases of succinylcholine-induced loss of sight, and an often-cited article described the use of succinylcholine in 71 patients with an open globe without a single instance of eye content extrusion. Fortunately, reasonable alternatives to succinylcholine exist, such as rocuronium or high-dose vecuronium. If a situation arises whereby the anesthesiologist believes that succinylcholine is required to relieve acute life-threatening airway obstruction, then it should be used immediately.
Lidocaine, in doses of 1 to 2 mg/kg, has been evaluated for attenuating the increase in IOP seen after laryngoscopy and intubation during halothane/N 2 O anesthesia, or after administration of succinylcholine. All doses of lidocaine were effective in decreasing, but not abolishing, the increase in IOP. Although there are no data evaluating the optimal timing of lidocaine administration, it is logical to administer it 1 to 3 minutes before intubation.
Unless specifically contraindicated, nondepolarizing neuromuscular blockers should be used during the maintenance phase of the anesthetic to ensure lack of movement that could endanger the contents of the eye. In an American Society of Anesthesiologists (ASA) closed claims analysis, lack of neuromuscular blockade and subsequent patient movement was commonly cited as the primary reason for vision loss. An additional safety procedure is the use of a skin-tight barrier across the bridge of the nose to prevent nasal secretions from entering the eye during an open procedure and introducing potential infectious organisms.
In many cases, a deep extubation may be warranted to avoid acute increases in IOP during emergence, assuming there are no contraindications (e.g., full stomach, difficult airway). Lidocaine may attenuate the acute increase in IOP that may occur during emergence when the child reacts to the endotracheal tube, but no studies have specifically examined this issue.
Postoperative Considerations
Except for lacrimal duct probing, most children who undergo eye surgery either have their operative eye patched or have some impairment of vision in the immediate postoperative period. This can cause a great deal of confusion and annoyance for the child. Parents should be allowed to comfort their children as soon as possible in the postanesthesia care unit (PACU). For hospitalized patients, mild sedatives and anxiolytics can be titrated to effect. Postoperative pain can be disabling. Eye surgery patients describe this feeling as having a foreign object stuck in their eye. Therefore, the child should be comforted and ongoing pain or agitation treated with oral or parenteral opioids, nonsteroidal antiinflammatory drugs (NSAIDs) such as ketorolac, or dexmedetomidine to induce sleep.
Anesthetic Management of Common Pediatric Ophthalmologic Procedures
Lacrimal Duct Probing and Irrigation
Many infants are born with a blocked nasolacrimal (tear) duct, but more than 90% of cases resolve with conservative management (external massaging of the duct) by 1 year of age. Some families may choose to undergo this procedure earlier than 1 year of age because of constant eye irritation or recurrent infections. The procedure, which usually takes less than ten minutes to complete, involves the placement of a fine metal probe from the opening of the duct through to its exit in the nasal cavity, followed by irrigation to confirm that it is patent ( Fig. 27.1 ). Occasionally, the probing includes moving a portion of the inferior turbinate, which can result in minor bleeding. In refractory cases, a silicone stent is placed into the duct, or balloon dilatation is performed.
