Assia Pupil Expander useful for small pupils in routine and complex cataract surgeries

Issue: April 10, 2017

ByEhud I. Assia, MD

A well-dilated pupil is optimal for cataract surgery, including laser-assisted procedures, because it provides greater access to the cloudy lens, thus facilitating the surgical procedure and minimizing potential surgical complications. A small pupil not only limits visualization of the lens but may be associated with increased iatrogenic iris damage during cataract surgery that may be permanent and contributes to increased iris-related inflammation that may even cause postoperative macular edema, a poor visual outcome and an unhappy patient. A small pupil that does not dilate easily may be associated with previous long-term miotic therapy, pseudoexfoliation, posterior or anterior synechiae to the surrounding intraocular structures from previous traumatic injury, previous intraocular surgery, or chronic intraocular inflammation, diabetes or use of systemic selective alpha blockers for benign prostatic hyperplasia.

Surgical options to expand pupillary size during surgery include intracameral pharmacologic agents such as buffered lidocaine (Shugarcaine, named after Joel Shugar, MD) that contributes to iris sphincter paralysis, bisulfite-free epinephrine that stimulates the pupil dilator, or a combination of both lidocaine and epinephrine as in epi-Shugarcaine. Omidria (phenylephrine 1% and ketorolac 3% injection, Omeros) is a newer FDA-approved pharmacologic agent. Use of ophthalmic viscoelastic devices such as Healon GV or Healon5 (both Abbott Medical Optics/Johnson & Johnson Vision) can provide temporary pupil expansion during cataract surgery. Other approaches include incisional sphincterotomies or bimanual pupillary stretching with iris or Kuglen hooks, taking care to limit potential iris damage from such maneuvers. Pupil expansion devices and instrumentation such as the Graether pupil expander (EagleVision), Beehler pupil dilator (Moria), Visitec I-Ring pupil expander (Beaver-Visitec) and Malyugin ring (MicroSurgical Technology) help cataract surgeons to better deal with small pupils and optimize surgical safety.

In this column, Dr. Assia describes the Assia Pupil Expander to assist in small pupil cataract surgery.

Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor

A small pupil is still a significant challenge in cataract surgery and may lead to severe complications. In recent years, intraoperative floppy iris syndrome (IFIS) following intake of alpha-1A adrenergic blockers for benign prostatic hypertrophy is yet another cause of intraoperative constricted pupil. It is estimated that about 5% of all cataract operations are performed through pupils smaller than 4 mm to 4.5 mm, corresponding to more than 150,000 cases annually in the U.S. and about 1 million cases worldwide. Means to dilate the constricted pupil include mechanical stretching, sphincterotomies, iris hooks and intraocular pupillary rings, with the Malyugin ring being currently the most popular option. Iris hooks typically require four additional side-port incisions, and insertion and removal are time consuming. There are numerous pupillary rings, open or closed, of various materials. The main advantage of the rings over the hooks is that they are inserted through the main corneal incision and do not require additional openings; however, they all require intraocular manipulations for the insertion, positioning and removal of the rings. In the rare cases with no capsular support, a ring may potentially dislocate posteriorly into the vitreous cavity.

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Technique

The APX (Assia Pupil Expander, APX Ophthalmology) was designed to provide safe and effective pupil dilation with minimal intraocular manipulations. Two disposable devices are used in each case, inserted through two opposite 19-gauge (1.1 mm) side-port incisions. The closed scissors-like device is inserted into the anterior chamber parallel to the iris plane and slowly opened while the distal curved tips are positioned behind the iris sphincter. When located in the proper position, the APX is slowly released to its final spread.

Figure 1. Uveitic cataract. Posterior synechia is seen at 3:30 (a). The APX device is opened halfway, and the blunt tips are positioned behind the iris. Then the device is slowly released (b). The same procedure is done on the opposite side (c). A wide pupillary aperture allows comfortable anterior continuous curvilinear capsulorrhexis. Note that the capsulorrhexis forces do nor override any element of the pupil expander (d). Phacoemulsification is done using routine instruments and technique (e). IOL implanted within the capsular bag. The entire anterior continuous curvilinear capsulorrhexis is visible (f). The APX is removed using the designated forceps (g.) At the end of the procedure, the pupil regains its circular shape and diameter (h).

Figure 2. Subluxated lens in an eye of a patient with Marfan syndrome. After capsulorrhexis is performed through the dilated pupil, the capsular anchor is inserted to secure the capsular bag to the scleral wall (a). At the end of procedure, the posterior chamber IOL is centered and stable. The capsular anchor is partially seen at the 11:30 position (b).

Figure 3. Nanophthalmic eye (axial length 18.9 mm). The APX is positioned despite shallow anterior chamber (a). A very hard cataract is removed by direct visualization (b).

Figure 4. Morgagnian cataract. APX is utilized to dilate the relatively small pupil (a). The milky white cortical material is aspirated before anterior continuous curvilinear capsulorrhexis (b). Dense small nucleus is phacoemulsified at the center of the visual axis (c). IOL implantation in the bag (d).

The second device is then inserted through the opposite incision in a similar manner to create a quadrangular 6 mm × 6 mm opening. Alternatively, the second incision can be slightly skewed to create a trapezoidal-shaped pupillary opening, the wider base facing the surgeon. This provides a large “device-free” area for the phaco tip and the second hand instrument so that the surgical instruments do not override any element of the pupil dilator, as necessarily occurs using pupillary rings. In case the terminal tips are not located properly behind the iris in the first attempt, the APX is regrasped and repositioned until properly placed. At the end of the operation, removal of the pupil expanders is done by using the same designated forceps in a reversed manner. No intraocular manipulations or any additional instruments such as lens hooks or manipulators are needed for the insertion, positioning or removal of the APX devices.

Use of the expander

I have personally used the APX in more than 50 cases, including some complicated cases such as:

Pseudoexfoliation syndrome;
IFIS;
Uveitis with posterior synechiae;
Mature and hypermature cataracts (including one case of Morgagnian cataract);
Narrow angles and shallow anterior chamber, including one case after angle closure glaucoma and two nanophthalmic eyes (axial length of 19 mm and less);
Iris coloboma (using one device only, located superiorly);
Scleral-fixated IOLs (one suture fixated and one glued IOL);
Iris fixation posterior chamber IOL, one case;
Pars plana vitrectomy, three cases;
Subluxated lenses, two eyes in cases of Marfan syndrome using capsule stabilizing devices (capsular anchor); and
Manual extracapsular cataract extraction (very dense cataract).

In the four cases with IFIS, the iris was relatively taut and did not prolapse through the incisions.

In all cases the pupil was effectively dilated, and all operations were completed successfully. No device-related adverse events were recorded except for a single case of head-nodding inadvertent touch of the anterior capsule with the tip of the APX, which resulted in a tear of the capsule. The pupils typically resumed a central and circular shape; however, sphincter defects were occasionally seen in eyes with fibrotic pupils or posterior synechiae.

In conclusion, the APX is effective for pupil dilation in routine as well as complex cataract operations and may serve as an alternative option in cases of small pupil and IFIS.

References:
Akman A, et al. Ophthalmology. 2004;doi:10.1016/j.ophtha.2004.02.008.
Jhanji V, et al. Middle East Afr J Ophthalmol. 2011;doi:10.4103/0974-9233.75888.
Kershner RM. J Cataract Refract Surg. 2002;doi:10.1016/S0886-3350(02)01206-3.
Lindstrom RL, et al. Clin Ophthalmol. 2014;doi:10.2147/OPTH.S69710.
Papaconstantinou D, et al. Clin Interv Aging. 2016;doi:10.2147/CIA.S97254.
Shugar JK. J Cataract Refract Surg. 2006;doi:10.1016/j.jcrs.2007.02.011.

For more information:
Ehud I. Assia, MD, can be reached at Meir Medical Center, 59 Tshernichovsky, Str Kfar-Saba, 44281, Israel; email: assia@netvision.net.il.
Edited by Thomas “TJ” John, MD, a clinical associate professor at Loyola University at Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at email: tjcornea@gmail.com.

Disclosures: Assia reports he is founder, partner and chief medical officer of APX Ophthalmology and is a consultant for Hanita Lenses. John reports no relevant financial disclosures.