Disclaimer: This article is intended solely for informational and educational purposes only. It does not constitute medical advice.
Anesthesia management of glaucoma surgery must balance akinesia, analgesia, and patient comfort against a vulnerable optic nerve and a dynamic intraocular pressure (IOP). Most glaucoma procedures involve the anterior segment and can be performed under regional or topical anesthesia, although medication use, topical glaucoma therapy, and IOP control shape the choice of technique [1].
The central concern in adults is injection behind the globe. Retrobulbar-space injections can raise pressure and reduce perfusion to an optic nerve that is already compromised in glaucoma [1]. Retrobulbar blocks also carry the greatest severity of complications among regional techniques, including optic nerve injury, retrobulbar hemorrhage, and globe perforation. Central nervous system complications are reported in 0.09% to 1.50% of patients and orbital hemorrhage in 1.7% [1]. When a block is preferred for trabeculectomy, an anterior sub-Tenon’s block is recommended because it places less stress on the optic nerve [1].
Topical anesthesia offers an alternative for appropriate glaucoma patients. In trabeculectomy and aqueous shunt surgery, it is associated with greater pain and a higher requirement for intraoperative intravenous anesthetic than regional blocks. This must be weighed against avoiding globe perforation, retrobulbar hemorrhage, optic nerve injury, and central nervous system depression [1]. In one comparison for drainage device implantation, retrobulbar block produced greater discomfort during injection, no difference in intraoperative or postoperative pain, and a less favorable safety profile than topical agents [1].
Topical anesthesia is also the only option indicated for peripheral iridotomy in angle-closure glaucoma. Non-penetrating procedures such as deep sclerectomy and viscocanalostomy may be performed under any anesthetic class, though general anesthesia is typically not considered [1]. Clinicians should also recall that subconjunctival 2% lidocaine may impair trabeculectomy healing, although evidence on the effect of anesthetic technique on surgical outcomes remains sparse [1].
Although it also increases IOP, peribulbar block remains in use as well. In a randomized trial of eyes undergoing subscleral trabeculectomy, mean IOP rose from roughly 26 to 28 mmHg before injection to approximately 29 to 30 mmHg across all groups [2]. The trial tested dexmedetomidine 25 µg and 50 µg as adjuvants, hypothesizing that it would mitigate this increase. It did not, and no between-group IOP differences appeared at any time point [2]. However, dexmedetomidine did shorten block onset from six minutes to 3.57 minutes and prolong duration from 160 to 252 minutes at the higher dose. No sedative effect was observed [2].
Pediatric patients present a different problem. Surgery in young children is almost always performed under general anesthesia because this population tolerates surgery poorly and may move [1]. Pediatric glaucoma is primarily treated surgically, since medications are often ineffective or poorly tolerated. Brimonidine can cause central nervous system depression, hypotension, bradycardia, and respiratory difficulty, and systemic acetazolamide may cause clinically significant metabolic acidosis in infants and children [3]. Because of these effects, IOP-lowering medications are often used only as temporizing measures, and anesthesiologists should review recent exposure preoperatively [3].
Surgical choice can also affect anesthetic burden. Valved tube shunts may be advantageous over some nonvalved devices because they require only one procedure under general anesthesia [3]. Finally, IOP targets must be interpreted in context, since inhalational anesthetics may lower IOP and success criteria are lower when measured under general anesthesia [3].
Anesthesia management of glaucoma surgery favors techniques that avoid additional stress on the optic nerve, namely topical or anterior sub-Tenon’s anesthesia in adults and general anesthesia in young children. Selection should account for patient cooperation, comorbidities, procedure type, and surgical team experience [1].
References
- Pucchio A, Pur DR, Dhawan A, Sodhi SK, Pereira A, Choudhry N. Anesthesia for ophthalmic surgery: an educational review. Int Ophthalmol. 2022. https://doi.org/10.1007/s10792-022-02564-3
- Ali H, Eissa S, Magdy H, Khashba M. Dexmedetomidine as an additive to local anesthesia for decreasing intraocular pressure in glaucoma surgery: a randomized trial. Anesth Pain Med. 2020;10(3):e100673. https://doi.org/10.5812/aapm.100673
- Chen TC, Chen PP, Francis BA, Junk AK, Smith SD, Singh K, Lin SC. Pediatric glaucoma surgery: a report by the American Academy of Ophthalmology. Ophthalmology. 2014;121(11):2107-2115. https://doi.org/10.1016/j.ophtha.2014.05.010