Methods for Achieving Adequate Pupil Size in Cataract Surgery

Andrzej Grzybowski; Piotr Kanclerz

Disclosures

Curr Opin Ophthalmol. 2020;31(1):33-42. 

In This Article

Pharmacological Treatment of the Small Pupil

Preoperative Management

Three types of topical agents are commonly used to obtain and sustain intraoperative mydriasis: anticholinergic agents, sympathetic agents and NSAIDs. Anticholinergic agents (such as tropicamide 1% or cyclopentolate 1%) act by blocking the parasympathetic muscarinic acetylcholine receptors located in the iris sphincter muscle. Sympathetic agents (such as phenylephrine 2.5 or 10%) induce adrenergic mydriasis by overstimulation of the α1-receptors of the iris dilator muscle with subsequent continuous iris contraction.

NSAIDs inhibit the release of prostaglandins and allow maintaining adequate pupil size, as intraoperative miosis is induced by surgical trauma and the release of prostaglandins.[37] Corticosteroids inhibit the synthesis of both prostaglandins and leukotrienes by blocking phospholipase A2.[38] Thus, theoretically, they could also support maintaining intraoperative mydriasis. However, Shaikh et al.[39] reported that with the presence of epinephrine 1 : 106 in the irrigating solution, neither flurbiprofen 0.03%, nor prednisolone 1% allowed to sustain mydriasis during the critical steps of cataract surgery.

Although diabetic patients respond relatively poorly to mydriasis with topical tropicamide 1%, in several cases it might be achieved by additional application of topical phenylephrine.[11] A 10% concentration is recommended, particularly in cases with darkly pigmented iris.[40]

Intraoperative Management

For intraoperative management of a small pupil a stepwise approach is recommended; injection of pharmacological agents into the anterior chamber might be the first choice in aiding pupil dilation. Moreover, in some cases intracameral drugs can be used instead of topical treatment. An advantage of intracameral application is easier preoperative preparation and more rapid pupil dilation.[41] Another issue is better bioavailability compared with topically administered substances, which have significant systemic absorption.[42] This effect should be concerned particularly with topical application of sympathetic agents, in patients with potential cardiovascular risks, in unstable cardiac arrhythmia or uncontrolled hypertension.[43,44] Nearly a half of the patients undergoing cataract surgery suffers from hypertension which even if medically controlled has a risk for preoperative blood pressure (BP) rise.[42]

Sympathetic agents are used topically, and similarly they might be injected into the anterior chamber for example, sterile epinephrine in a 1 : 2500 dilution.[45] In the study by Bekir et al. 0.25 ml of phenylephrine 2.5% was administered into the anterior chamber in 421 patients undergoing cataract surgery. A statistically significant, but clinically insignificant rise in mean arterial pressure from 106.6 to 108.0 mmHg was noted.[43] Other studies did not find BP or heart rate alterations after injection of 0.3 ml of three phenylephrine hydrochloride 2.5% minims mixed with 0.3 ml of balanced salt solution[46] two to three drops of 0.1% epinephrine diluted in 1 ml of saline[47] or intraocular irrigation with 1 : 1000 000 epinephrine.[48]

Another option to achieve mydriasis is the application of intracameral preservative-free lidocaine hydrochloride 1%.[49–51] The mydriatic effect of a local anesthetic is associated with blocking the transmission of nerve impulses on the voltage-gated sodium channels; subsequently, pupil constriction to light is blocked. Intracameral application of lidocaine 1% (0.2–0.3 ml) provided rapid mydriasis, and greater pupil dilation than preoperative cyclopentolate 1% and phenylephrine 5%.[51] Another possibility is to supplement the irrigating solution with epinephrine in the concentration of 1 : 106.[39,52]

Several combinations of intracameral drugs can be used. One option is intracameral application of a solution of phenylephrine 1.5% and lidocaine 1%.[53] Lundberg and Behndig[42] proposed the use of cyclopentolate hydrochloride 1 mg, phenylephrine hydrochloride 15 mg, and lidocaine hydrochloride 10 mg with the addition of sodium edetase 1 mg, boric acid 3.85 mg (for isotony), and aqua injectable to a total volume of 1 ml prepared by the pharmacy. Currently, preparations for intracameral administration are available commercially.

Finally, application of an ocular visoelastic device (a maximally cohesive agent is indicated) might be suitable for viscomydriasis and preventing the iris to prolapse, particularly in IFIS cases[22]

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