Commentary: Intracameral mydriatics in cataract surgery

Adequate mydriasis is crucial for any cataract surgery. The incidence of complications increases in a poorly dilated pupil. Conventionally, the pupil is dilated with a standard regime of topical drops (diluted for infants), given preoperatively starting a few hours before surgery. Topical drops have reduced penetration and take time to have their peak effect.[1,2] Therefore, a larger dose with repeated applications is required. This is supplemented with adrenaline in the irrigating fluid to maintain mydriasis. These drugs are absorbed into systemic circulation and can cause systemic cardiovascular and pulmonary side effects. These systemic side effects of topical mydriatics are more pronounced in children.[3,4]

An alternative method to dilate the pupil is the use of intracameral mydriatics. There have been numerous studies on the use of this solution during cataract surgery.[1,5,6,7] It would be well worthwhile exploring its role in a well-designed study on small-incision cataract surgery where a larger pupil is required for anterior capsulorhexis and expressing the lens. The use of intracameral injection can obviate the need for topical drops and their associated side effects. The efficacy and safety of a fixed dose intracameral combination of phenylephrine (0.31%), tropicamide (0.02%), and lidocaine (1%) in phacoemulsification is already established in adults.[5,6,7] The formulations have been proven to be effective and are a safe alternative to the standard topical regime for establishing and maintaining intraoperative mydriasis and analgesia. It has been shown to be effective in floppy iris syndrome. Not only are they efficacious, but they are also reportedly comfortable to an adult patient.[7,8] The effect of lidocaine in causing paralysis of the iris sphincter and decrease in pain might contribute to maintaining pupil stability. Pupils might be larger initially, but intraoperative miosis is more common and unpredictable with topical dilators. Sustained mydriasis is more critical to surgeons than the “maximum” size achieved.

Intraoperative miosis is a well-known problem with topical dilators.[5] These are more pronounced in children and in patients with diabetes and pseudoexfoliation.

In a pediatric age group, risk of poor mydriasis and intraoperative miosis is much higher compared to adults. Intracameral mydriatics have shown to be effective in dilating and maintaining the pupil size in children without any unexpected inflammatory sequelae.[9] The average pupillary dilation achieved (6.2 mm) was comparable to that reported (6.5–7.5 mm) in adults. Even when intraoperative miosis occurs with topical drops, intracameral dilators come to the rescue. Repeat injections do not have any additional effect on pupillary dilatation, possibly because of competitive binding of the iris receptors.

There are several advantages of using intracameral mydriatics over topical drugs. Apart from systemic side effects, topical mydriatics can cause ocular side effects from the preservatives. There is targeted delivery of the drug when using it as an injection without having to pass through the corneal barrier. Patient comfort increases with added local anesthetic when operating under topical anesthesia. In children, it is a safe option for those allergic to atropine. It is cost-effective compared to drops and improves operating room logistics. Thus, this combination could provide advantages of stable mydriasis and greater surgeon and patient comfort intraoperatively.