Optimal Method for Mydriasis in Cataract Surgery

Overview

Obtaining appropriate mydriasis prior to cataract surgery is an important variable in successful surgery. The current practice includes using topical anticholinergic and sympathomimetic agents in the preoperative area prior to cataract surgery, but the pupils are sometimes insufficiently dilated and can often need additional mydriasis with intracameral agents during cataract surgery. Pre-operative topical mydriatic drops take time to take effect, are mildly uncomfortable for the patient, and have a cost to the healthcare system. If intracameral mydriasis alone can achieve adequate pupil dilation, perhaps topical mydriatics would not be needed. The purpose of this study is to evaluate whether topical versus intracameral versus topical + intracameral mydriasis is the optimal way to dilate pupils during routine cataract surgery. The results of this study have implications for improving the efficiency and reducing time prior to cataract surgery. In addition, it has significant potential to reduce the cost associated with cataract surgery if preoperative drops can be eliminated.

Recent research has compared the use of intracameral and topical agents with the preoperative pupil size and cataract surgery success. Studies have compared topical mydriatics with intracameral lidocaine and found no significant difference in dilation. , Other studies have compared topical mydriatics with intracameral dilation that includes solutions with and without epinephrine in the irrigating solution and concluded that irrigating solutions without epinephrine can safely be used with intracameral mydriatics but epinephrine is useful when using topical mydriatics. There have also been studies comparing the success of longer acting drug inserts of mydriatic agents with the use of intracameral agents. In addition to these standard agents, different surgeons have used various formulations of topical and intracameral agents to perform mydriasis. As of yet, there is no formal, standardized method for mydriasis and no large prospective study comparing the outcomes of the various methods. Considerations such as cost and time spent on preoperative mydriatic agents in light of the amount of success seen with these agents calls into question the need for such agents. The investigators would like to study the amount of pupillary dilation seen with topical preoperative mydriatic agents compared to intracameral agents compared to the use of them both together. This will be a prospective randomized controlled trial. Patients will be consented and enrolled at their pre-op visit. They will be randomized to topical drops alone, intracameral injection alone, or topical plus intracameral mydriasis. All patients will receive intracameral lidocaine, as this is used for its anesthetic effect but also has some mydriatic effect. The intervention will take place on the day of the operation. Patients will be followed until post-operative month #1. Data will be gathered on 4 visits: pre-op clinic visit, day of operation, and post-operative day #1 and post-operative month #1. These are all standard visits for routine cataract surgery, and this study will not require the patient to make any extra visits. Enrollment will continue until the sample size is met. Patients cannot be blinded to whether or not they receive topical mydriasis eyedrops, and no placebo drops are necessary because patients cannot voluntarily control their pupillary constriction, so no placebo effect would be expected. The surgeon cannot be blinded to whether or not the patient has received topical mydriasis eyedrops in the pre-op area because it will be evident based upon whether or not the patient's eye is dilated. Another researcher who was not present in the operating room will grade the photographs and measure the pupil size, and this researcher will be blinded to which intervention the patient received. Currently, some surgeons use topical plus intracameral mydriasis for mydriasis during cataract surgery. It is hypothesized that intracameral mydriasis alone may be sufficient to adequately dilate the pupil for cataract surgery. Patients who are not adequately dilated at the time of pupil size measurement immediately before the capsulorrhexis step will subsequently receive additional pharmacologic mydriasis, visco-dilation, or iris expansion devices to dilate their pupil to a size that is adequate for their surgery. Therefore, no matter which group the patient is in, their pupil will be eventually dilated to a size that is adequate to proceed with surgery. There is no placebo or non-treatment group, since all patients must be somehow dilated in order to undergo cataract surgery. The purpose of this study is to compare 3 methods of dilation. The pupil size will be measured after the viscoelastic is injected and before the capsulorrhexis is performed. Treatment failure is defined as a pupil size that is clinically deemed too small to safely proceed with surgery (approximately less than 5 mm). At this point, a rescue intervention will be implemented with additional pharmacologic mydriasis, visco-dilation, or iris expansion devices, until the pupil is adequately dilated to proceed with surgery. These patients will still be included in the study, and their pupil size prior to the rescue intervention is still the primary outcome. Participants can choose to stop participating in the study prior to receiving any of the mydriasis agents. Should they choose to withdraw from the study, they would end up receiving routine mydriasis with topical plus intracameral agents. The study ends on post-op month #1 for all individual patients. The study enrollment period will end when the sample size is met.