Alan N. Carlson, M.D., Professor of Ophthalmology and Chief of the Corneal and Refractive Surgery Service at the Duke Eye Center was asked by Cataract and Refractive Surgery Today to review and edit the surgical “pearls” used for successful cataract surgery in patients with small, poorly dilating pupils. Patients undergoing cataract surgery with small pupils pose additional risk for potential complications. It is important to establish prior to surgery the ability to dilate the patient and factors that may hinder dilation. Identifying predisposing factors such as tamusolin (Flomax) usage or the condition of pseudoexfoliation is particularly important. Intraoperative “epi-Shugarcaine” is helpful in milder cases but inconsistent in patients with longstanding use of tamusolin. With regard to pupil stretching in non-IFIS cases like uveitis, less is more – meaning that it is easy to “over stretch” the pupil. You can do more if necessary but I teach trainees to stretch about half of what you think is needed and use viscomydriasis to do the rest. Relative to my colleagues, I am probably less likely to use a mechanical pupil expander, although I do think they can be beneficial when necessary. If the pupil is 3.5 mm or larger, mechanical aids for pupillary dilation are seldom needed with my technique as follows:
- Ensure that the patient has had additional time to achieve dilation in the pre-op holding area.
- I use a 2.2 mm keratome to make single plane incision parallel to the iris and I will often not go in all the way making the incision between 2.0-2.2 mm in length. By making this incision horizontal or parallel to the iris, I achieve a consistent length.
- I inject viscoelastic, typically Healon GV in my usual case with Healon 5 as backup for the more severe cases.
- Make the paracentesis incision after the primary incision to make sure that there is an optimal and ergonomic relationship between the two and also make this incision parallel to the iris, 1.0mm in width, avoiding wound construction that contributes to prolapse.
- Initiate the capsulorhexis centrally and spiral this out to the maximum that you can visualize. I will often allow it to go past the pupil border where I can no longer visualize it directly if I feel comfortable with the configuration of the tear and when “the Force” is with me.
- Cortical cleaving hydrodissection is critical but must not lead to turbulence or a gradient that causes iris prolapse. I try to get the canula under the capsule as close to the wound as possible. The wave then propogates posteriorly away from the wound. This is a brisk injection of a very small quantity of BSS (0.5-1.5cc). If I was successful in creating a capsulorhexis close to 4mm or more and I do not see a tendency for iris prolapse, I will often initiate a second wave that becomes the hydroexpression wave for a “pop and chop” procedure. This works incredibly well in advanced cases and I will link several videos that highlight this technique.
- I initiate phacoemulsification using a one-handed technique to with a low-flow, low-turbulence technique. Using a “second” instrument as needed but being careful to not allow this use to cause leakage and turbulence. Low energy and patience also reduce the risk of creating a wound burn (low flow) or iris injury. There is no single technique that works best for all of these cases so there is a lot of improvisation based on how the procedure is progressing but the principles remain consistent with regard to reducing turbulence. Maintain occlusion with the lens nucleus to reduce the risk of iris injury but don’t “lollipop” the nucleus.
- Cortex removal is best initiated in the sub-incisional location as this can be the most difficult and made additionally problematic in the small pupil patient. The remaining cortex expands the bag making subincisional cortex removal easier.
- Viscoelastic is instilled and the iris is gently retracted in all 4 quadrants to make sure that all lens material is removed.
- After the IOL is inserted, additional patience is needed to remove the viscoelastic as it is more likely to remain trapped behind the IOL in combination with a small capsulorhexis and pupil.
- Iris injury if fortunately less common; however, should it occur, I use Miostat at the end of the procedure to facilitate returning to a more normal pupil.
- I monitor IOP in the early postop period more closely in patients that undergo cataract surgery with small pupils.
It is import to counsel these patients prior to surgery as they need to recognize that in many cases, they can be far from routine and may require a longer period of time for post op recovery.