This column is one in an invited series by Dr. Osher. The series highlights techniques that may be helpful in particular to young practitioners.
This column will describe a technique that facilitates removal of the adult nuclear rim, usually adherent to the cortex when hydrodelineation is performed when removing the posterior polar cataract. The Escape Route is created to allow late hydrodissection to separate the epinucleus from the lens cortex and capsule leading to a safer procedure.
When Osher and Koch published the first series of posterior polar cataracts removed by phacoemulsification in 1990, the incidence of posterior capsule rupture was 26%.1 The surgery was performed using multimeridional hydrodissection in an attempt to avoid creating a forceful fluid wave that could raise the pressure behind the adult nucleus leading to a rupture of the thin central posterior capsule. A few years later, Dr. Abhay Vasavada demonstrated how hydrodelineation could facilitate central nuclear removal by separating the nucleus from the epinucleus.2 By preventing a more peripheral fluid wave, hydrodelineation seemed to protect the fragile posterior capsule and the incidence of posterior capsule tear decreased. Many surgeons have subsequently proposed different in situ techniques to manage the posterior polar cataract, but removal of the epinucleus remains a challenge because the fluid wave of hydrodelineation deliberately prevents a more peripheral cleavage plane between the epinucleus and the cortex.3 We describe a technique we call the Escape Route, which allows the advantage of mobilizing the more central fetal nucleus with hydrodelineation then allowing safe hydrodissection for mobilization of the adherent epinucleus without raising the risk of blowing out the posterior capsule.
After the surgeon has avoided overfilling the anterior chamber with an ophthalmic viscosurgical device, which could drive the nucleus backward through the posterior capsule, the manual capsulorhexis is completed followed by hydrodelineation. This step is the same if a laser capsulorhexis has been performed, also described by Dr. Vasavada.4 The delineated central fetal nucleus is removed with an in situ approach, which is less traumatic than rotating or decentering the lens.
The Escape Route
After hydrodelineation and emulsification of the fetal nucleus, there is inevitably an adult nucleus and epinucleus that is “stuck” to the cortex and capsule because hydrodissection has been avoided. With the phacoemulsification tip, the surgeon carefully burrows into the lens substance opposite the incision. Usually, the adult nucleus and epinucleus are soft because these patients are typically in the younger age group, allowing aspiration with the phacoemulsification needle. Then, the adjacent cortex opposite the incision is also aspirated, creating the so-called Escape Route. Now, it becomes safe to hydrodissect under the capsule with either a straight or a curved reverse cannula, which loosens the epinucleus, especially the subincisional epinucleus. Because the fluid wave can easily flow through the Escape Route, the remaining adult and epinucleus can be safely mobilized and then emulsified without stress on the posterior capsule. Although we prefer slow motion phacoemulsification with lower parameters, most strategies for removing the remaining nuclear layers will be effective once the adult nucleus and epinucleus have been separated from the cortex and capsule.5
The cortex can be removed using a coaxial, bimanual, or dry technique. We prefer a soft tip for enhanced safety, starting the cortical removal with the more difficult subincisional cortex because the capsular bag is held open by the cortical bowl. The stubborn cortex can be removed by gentle viscodissection, which is also safer because of the Escape Route. Although a central plaque can be opened after surgery with the Nd:YAG laser, we also describe a “minimal aspiration technique” where the surgeon taps the foot switch creating the lowest possible vacuum to clean the capsule by only the re-expansion of the tubing. If the posterior capsule tears, the surgeon should not withdraw the I&A tip, which would allow the chamber to shallow. The chamber must be maintained throughout these maneuvers to prevent rupture of the anterior hyaloid face leading to vitreous prolapse. The ophthalmic viscosurgical device must be injected through the second incision site, and then, the I&A tip can be safely withdrawn. The surgeon should be prepared to perform a posterior capsulorhexis, excising the plaque and the abnormally thin adjacent capsule followed by traditional optic capture, reverse optic capture, or prolapsing the optic through the posterior capsular opening into the Berger space (Video 1, https://links.lww.com/JRS/A621).
Even if the Escape Route has worked exactly as described and the lens has been safely removed leaving an intact posterior capsule, the surgeon must remain vigilant. As the intraocular lens is being injected, incidental contact between the leading haptic and the central posterior capsule may result in an unexpected capsular rupture. Posterior capsule rupture is even possible if the stream of fluid during hydration of the incision causes momentary capsular block. Every step of this procedure must be carefully planned and executed with caution. Although it is difficult to become experienced with these unusual cases, a knowledgeable surgeon who respects these principles has an excellent chance to achieve a successful outcome. We believe that the Escape Route technique adds to the safety of the procedure when the surgeon operates on the patient with a posterior polar cataract.
1. Osher RH, Yu BC-Y, Koch DD. Posterior polar cataracts: a predisposition to intraoperative posterior capsule rupture. J Cataract Refract Surg 1990;16:157–162
2. Vasavada AR, Raj SM. Inside-out delineation. J Cataract Refract Surg 2004;30:1167–1169
3. Foster GJL, Ayers B, Fram N, Hoffman RS, Khandewal S, Ogawa G, MacDonald SM, Snyder ME, Vasavada A. Phacoemulsification of posterior polar cataracts. J Cataract Refract Surg 2019;45:228–235
4. Vasavada AR, Vasavada V, Vasavada S, Srivastava S, Vasavada V, Raj S. Femtodelineation to enhance safety in posterior polar cataracts. J Cataract Refract Surg 2015;41:702–707
5. Osher RH. Slow motion phacoemulsification approach [letter]. J Cataract Refract Surg 1993;195:667