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Does [pupil] size matter? How premium surgeons can avoid the inevitable
When a pupil is at least 5.25 mm or greater at the start of the procedure, the main goal is to prevent intraoperative progressive miosis as the case proceeds.
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Every day when a premium surgeon enters the operating room to perform ophthalmic surgery, pupillary dilation — the portal to the operative field — will inevitably have a major stake in the success and outcome of the surgery. As a cataract surgeon, I am amazed how often intraoperative miosis and/or small pupils at the outset of a case can wreak havoc for even the most experienced anterior segment surgeons.
As we know, intraoperative miosis is frequently unpredictable or may be associated with conditions such as intraoperative floppy iris syndrome associated with systemic use of alpha-1 adrenergic antagonists (all ending with –osin), pseudoexfoliation syndrome, diabetes mellitus, prior history of uveitis, prior history of trauma or intraocular surgery, and most recently femtosecond laser-assisted cataract surgery (FLACS). Pupil size does matter, and a well-known colleague of mine, Johnny L. Gayton, MD, once reminded me that “pi r squared,” or the area of a circle, is probably the geometry lesson I slept through in high school. Intraoperative pupillary diameter, if starting at a 6-mm diameter, is reduced to 3.5 mm during surgery; this reduction represents a 66% reduction in operative viewing field for the surgeon. And most of us know what can happen next — a visit to our cardiologist postoperatively.
There are several pharmacological and surgical approaches to avoid the inevitable small pupil during surgery. When pupils are less than 5 mm from the outset, I still implement my personal preoperative pharmacological recipe of cyclopentolate 1%, two sets placed by patient at home prior to leaving for the surgery center, with repeat cyclopentolate 1%, phenylephrine 2.5%, and Prolensa (bromfenac 0.07%, Valeant Pharmaceuticals) at the surgery center. I then use one of many surgical devices for pupillary expansion, such as the APX spring-like device (APX Ophthalmology Ltd, Israel), Malyugen ring (MicroSurgical Technology), Grieshaber iris retractors (Alcon) or Beehler pupil dilator (Moria). Personally, I find the disposable APX device to give the best pupillary dilation and is the easiest to remove from the eye at the end of the case. I use MST capsular tension hooks to keep pupils larger and stabilize the capsular bag for phacoemulsification when there is brittle pseudoexfoliation and significant phacodonesis seen at the slit lamp preoperatively. Ike K. Ahmed, MD, FRCSC, has a novel technique of using iris retractors to stabilize a zonular compromise and gluing in the back end of the iris retractor into a scleral tunnel no different than the glued IOL technique described by Amar Agarwal, MS, FRCS, FRCOphth. When a pupil is at least 5.25 mm or greater at the start of the procedure, my main goal is to prevent intraoperative progressive miosis as the case proceeds. In FLACS cases, I always place a drop of Paremyd (hydroxyamphetamine hydrobromide 1%/tropicamide 0.25%, Akorn) immediately after the femtosecond portion of the cataract procedure is completed.
Historically, I would use intracameral “Shugarcaine” (phenylephrine/epinephrine/lidocaine preservative-free solutions in appropriate diluted mixtures) to avoid miosis, but much of this effect initially gets “washed out” as the procedure carries on, especially in complex cataract cases. I have now switched to the newest FDA-approved Omidria (phenylephrine 1% and ketorolac 0.3% injection, Omeros Corporation), which is approved to prevent intraoperative miosis and reduce postoperative pain in adults. The advantages of Omidria are that its 4-mL single-use vial is easily added to a 500-mL container of standard BSS irrigation solution, it delivers steady-state concentrations to the anterior chamber throughout the procedure, it is preservative-free and bisulfite-free (reducing the risk of toxic anterior segment syndrome), and it is Medicare reimbursed via the CMS transitional pass-through process. It has the advantage of not being a compounded product, which is frowned upon by many state accreditation agencies. Omidria is a safe, well-tolerated and efficacious pharmaceutical option as seen in the FDA clinical trials in which approximately 30% of patients treated with Omidria vs. placebo avoided a pupil diameter decrease of greater than or equal to 2.5 mm, and up to 85% of patients never had a pupil less than 6 mm at any time during cataract surgery. The main disadvantage is that not all insurance carriers cover the use of Omidria yet.
In the end, pupil size does matter and maintaining pupillary dilation either through surgical or pharmacological maneuvers as described will definitely avoid the inevitable. Complex cataract cases can now be more manageable especially in conjunction with other advanced technologies such as FLACS and intraoperative aberrometry.
- References:
- Chang DF. J Cataract Refract Surg. 2005;31:664-673.
- Crandall AS. Cataract and Refractive Surgery. New York, NY: Springer-Verlag; 2006.
- Chang D, et al. Ophthalmology. 2014;121:829-834.
- Safety and Efficacy of OMS302 in Patients Undergoing Intraocular Lens Replacement (NCT01454063 and NCT01579565). Available at: https://www.clinicaltrials.gov.
- Schultz T, et al. J Refract Surg. 2015;doi:10.3928/1081597X-20131021-03.
- Shugar JK, et al. J Cataract Refract Surg. 2006;32:1074-1075.
- Lindstrom RL, et al. Clin Ophthalmol. 2014;8:1735-1744.
- For more information:
- Mitchell A. Jackson, MD, can be reached at Jacksoneye, 300 N. Milwaukee Ave., Suite L, Lake Villa, IL 60046; email: mjlaserdoc@msn.com.
Disclosure: Jackson reports he is a consultant for Omeros and APX Ophthalmology.