Pupillary problems are commonly associated with increased intra- and postoperative complications. When faced with a challenge such as a small pupil, a floppy iris, or intraoperative miosis, the best approach is to pinpoint its cause and deploy a plan of attack before it has a negative effect on the surgical outcomes.

THE CAUSE

Small pupils. The major causes of small pupil include pseudoexfoliation (PXF) syndrome, diabetes, the use of certain systemic drugs, age-related pupil dilator atrophy, trauma, uveitis, long-term use of miotics for glaucoma, and multiple types of previous surgeries including trabeculectomy and phakic lens implantation. In the presence of such conditions, it may be difficult to dilate the pupil with current dilatation protocols.

Floppy iris. Awareness of intraoperative floppy iris syndrome (IFIS) has increased since its description in the past decade by Chang and Campbell,¹ leaving surgeons to determine the best surgical course for these patients. This condition is characterized by poor dilation of the pupil, intraoperative progressive miosis, billowing of the iris tissue, and iris prolapse through the ocular incisions during cataract surgery. Largely associated with the use of systemic alpha-1 blockers such as tamsulosin, IFIS may also be linked to other systemic medications, such as nonselective alpha-blockers² that may cause a decrease or lack of iris dilator smooth muscle tone. IFIS can be classified according to the severity of presentation: mild (billowing only), moderate (billowing and intraoperative miosis), or severe (billowing, miosis, and iris prolapse).^3,4

Although IFIS is the most likely cause of a floppy iris, it can also occur in traumatic cataracts that are accompanied by severe damage to the iris or in any condition that causes derangement in the iris dilator muscle tone. Intraoperative miosis. Pupil constriction can be a side effect of IFIS, as mentioned, or it can be caused by intraoperative iris trauma. It may also occur in postvitrectomy eyes, highly myopic eyes, and eyes with weak zonules. In these cases, fluctuations in anterior chamber depth can induce miosis as surgery progresses. Whatever the cause, eyes with pupil problems represent a surgical challenge.

SURGICAL APPROACHES

At our center, we have achieved an extraordinary cataract surgical technique with great efficacy and safety and rapid visual recovery. But today’s patients have greater expectations and are more demanding, wanting not only to see better postoperatively but to achieve a good aesthetic appearance. Therefore, in the approach to these particularly complicated cataract surgical cases, the main goals are to obtain reasonable and sustainable dilatation, avoid potential complications such as iris prolapse, and maintain normal pupil shape and function after surgery. To achieve these goals, many strategies have been described, from pharmacologic approaches to the use of a variety of mechanical devices and techniques. In the specific case of IFIS, the range of severity and incidence has led to a diversity of approaches with varying success.

Pupil problems can present in isolation or in association with other ocular conditions, such as a shallow anterior chamber, weak zonules, low endothelial cell density, and dense cataract, which not only increase the risk of complications but affect the surgical options.

Because there are no universal solutions for pupil problems, the strategies chosen for pupil enlargement, miosis prevention, and the avoidance of iris prolapse depend greatly on the surgeon’s skills and preferences as well as the intraoperative situation. Rather than try to describe the numerous surgical techniques, below I offer my top 10 tips to prevent intra- and postoperative complications in the presence of pupil problems.

Tip No. 1: Perform a thorough preoperative exam that includes the patient’s history and a listing of current and past medications. Anticipation is always a good strategy. Identifying patient risk factors before surgery may spare intra- or postoperative complications and help the surgeon to prepare the surgical course, modifying the steps of cataract surgery as necessary. If complications are expected, it is important to explain the possible problems and outcomes to the patient, so that his or her level of expectations can be adjusted. This also helps the patient stay calm and cooperative during surgery.

Tip No. 2: Adopt a step-by-step approach. It is advantageous for surgeons to be familiar with several strategies from which they may select one or a combination according to the situation and the surgery’s progress. Whatever technique is chosen to treat pupil problems during cataract surgery, it should adhere to the following two principles: (1) ensure a stable anterior chamber throughout the procedure with balanced pressure gradients and (2) avoid as much iris manipulation as possible. Following these two principles will not only reduce the incidence of intraoperative complications but also dull the eye’s postoperative inflammatory response.

Tip No 3: Use lidocaine in addition to topical anesthesia. If I anticipate pupillary problems, or if a patient’s pupil is not dilating with our current topical protocol, I use my standard topical anesthesia but add an intracameral injection of 0.2 to 0.3 mL of 1% preservative-free lidocaine. This injection has a dual effect, promoting anesthesia and providing a certain degree of pupil dilatation due to iris nerve palsy.⁵ During this instillation, I check the behavior of the iris, as the appearance of billowing with the irrigation fluid is a warning sign for the presence of IFIS.

Tip No. 4: Avoid aggressive stretching maneuvers that can permanently damage the iris sphincter. In the presence of posterior synechiae, gently releasing the adherences with an ophthalmic viscosurgical device (OVD) or spatula or performing a pupillary membranectomy⁶ or synechiarhexis with forceps (Figure 1) followed by viscomydriasis with a high-viscosity OVD enables sufficient enlargement of the pupil in most cases. Performing mechanical stretching before these maneuvers can cause anterior capsular rupture. With the increase in cases of IFIS, I avoid over-stretching the iris. Although the IFIS pupil is not fibrotic and typically can be stretched without tearing the sphincter muscle, this maneuver should not be used in these cases. This is because it is not effective (usually the pupil returns to its original shape due its elasticity) and can worsen the situation by increasing the floppiness of the iris.⁷

Tip No. 5: Perform viscomydriasis very slowly. This is advisable to avoid trapping of the aqueous humor, leading to intraocular pressure (IOP) rise. For this purpose, I use DisCoVisc (Alcon Laboratories, Inc., Fort Worth, Texas), a high-viscosity OVD with cohesive and dispersive properties. Depending on the type of pupil problem, I inject the OVD in the center or near the edge of the pupil, trying to not over-inflate the eye at the beginning of the procedure and bringing about safe viscomydriasis. Whenever necessary, I repeat instillation of the OVD to maintain pupil dilatation or to move the iris away from the incisions. Always be alert to the IOP gradient, particularly during hydrodissection.

Tip No. 6: Use a pupil expander. If after topping up the OVD I am still unable to increase the size of a small pupil, I insert a mechanical device such as the Malyugin Ring (MicroSurgical Technology, Redmond, Washington) to facilitate pupil expansion before proceeding with the capsulorrhexis. I prefer to use the 6.25-mm size ring because it does not stretch the iris too far and allows me to perform the capsulorrhexis with ease. This is my first choice in PXF (Figure 2) and IFIS because in the first case good visualization of the capsule during capsulorrhexis and phaco is paramount, and in the second case it serves to avoid intraoperative miosis and to reduce the incidence of iris prolapse.⁸ In the presence of weak or loose zonules, I prefer to use disposable iris retractors and to perform the capsulorrhexis through the sideport incision with a microforceps before creating the main incision. I then transfer the iris retractors to hold the capsular bag (Figure 3). This produces a very stable capsular bag and anterior chamber and maintains dilatation without the need to stretch the iris with the retractors.

Tip No. 7: Place the main incision superiorly. I create a clear cornea 2.2-mm main incision, placing it superiorly because the anterior chamber is deeper superiorly than temporally.⁹ This can be a helpful strategy in cases of potential iris prolapse. In case of iris trauma, the risk of postoperative visual problems is reduced by a superior approach because the incision site is covered by the upper lid. Additionally, I always create two smaller sideport incisions to perform bimanual I/A, which can be especially useful in the presence of loose zonules or in a highly myopic eye. These dual sideport incisions provide complete access to the anterior chamber and allow me to switch placement of the instruments. All the incisions must be as small and square as possible to avoid leakage and access to the iris root.

Tip No. 8: Always work in the center of the pupil. When performing phacoemulsification in a case with intraoperative miosis, I keep the instruments as central as possible in the pupil and work in this so-called safety zone, because I can visualize the instruments and make sure they do not dip behind or touch the iris. I use a quick chop or vertical chop maneuver to fracture the nucleus and then bring the pieces anterior to or into the plane of the iris for removal (Figure 4), sometimes injecting DisCoVisc under the nuclear pieces to float them out of the capsular bag, to inflate the capsular bag, or to expand the pupil. I always use torsional phaco with the Ozil handpiece and IP software (Alcon Laboratories, Inc.), because it allows me to work with very low turbulence and a stable anterior chamber— important factors when dealing with these cases. With this approach, I rarely feel the need to use a pupil expander in this stage of cataract surgery.

Tip No. 9: Use bimanual I/A. In comparison to coaxial, bimanual I/A helps maintain a closed anterior chamber and stable IOP. Bimanual I/A has the advantage of separating the infusion from the aspiration so that fluid currents in the eye can be carefully controlled. Additionally, the ability to switch hands allows full access to the capsular bag and complete removal of the cortex even in small pupils (Figure 5). The handpieces can be used via two small paracentesis incisions, preventing excessive leakage from the main incision that can lead to iris prolapse. I use bimanual I/A in most of my cases, and it is a great help in the management of pupil problems due the versatility and safety of the procedure.

Tip No. 10: Implant a one-piece IOL whenever possible. Three-piece lens designs are more difficult to implant because they require more rotation than a onepiece lens, and the proximal haptic can drag the iris. One-piece lenses also unfold gently within the eye. If the pupil is very small, I typically use a spatula to guard the iris from any lens touch during IOL implantation. After the lens is implanted, I use the bimanual I/A handpieces or a spatula to ensure proper positioning of the haptics, as it is common with a small pupil to end up with one haptic in the capsular bag and the other in the sulcus. In cases that require three-piece IOL implantation in the sulcus, try to capture the optic behind the anterior or posterior capsulorrhexis, as the presence of abnormal iris increases the chance of postoperative iris capture of the optic.

Bonus tip: At the end of surgery, carefully remove the OVD from the eye to avoid collapse of the capsular bag and iris prolapse. The highly retentive OVDs usually used in cases with pupil problems can mask a mismatched pressure gradient. I use one of the bimanual I/A handpieces to hold the lens during aspiration of the OVD. One of the disadvantages of bimanual I/A is the lower capacity of irrigation flow and the time-consuming nature of the OVD aspiration. In these cases, however, this is an advantage, as it allows me a higher control of fluidics and a gentle procedure. Also in this phase I check for the presence of any hidden or trapped lens fragments.

CONCLUSION

Small pupils, floppy irises, and intraoperative miosis are three pupil problems that can complicate routine cataract surgery. In these cases, the length of the procedure will undoubtedly be longer than a normal procedure, but as I tell my residents, the extra time you spend during surgery will spare a lot of time after surgery. It is crucial to take your time and perform all the necessary maneuvers to ensure a safe procedure in the presence of pupil problems. Therefore, further complications can be avoided, and postoperative patient counseling can be kept to a minimum.

Isabel Prieto, MD, is Chief of the Ophthalmology Department at the Professor Fernando Fonseca Hospital, Lisbon, Portugal. Dr. Prieto states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +35 1 217781991 or +35 214348290; e-mail: isabelprieto@netcabo.pt.

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