A patient with a dense cataract and pupillary miosis can not only test the skill and patience of even the most experienced cataract surgeon, it can also shake the confidence of those in training.
This is because the obscured visualization of the capsule and nucleus can wreak havoc on the key elements of a successful surgery – seriously limiting the ability to create the desired capsulorhexis, safely removing the lens material, or effectively inserting an intraocular lens (IOL).
Complications attributed to inadequate capsulorhexis or poor visualization of the peripheral nucleus during phacoemulsification can include anterior capsule tears, posterior capsular rupture (with or without vitreous loss), zonular dialysis/dehiscence, and nuclear fragment loss.1 These eyes are also at higher risk of iris damage, leaving patient with increased postoperative inflammation and iris defects that can be cosmetically unappealing or cause visual disturbances.
Keeping all these factors in mind, combined with the well-known phacoemulsification learning curve, eyes with dense cataract and pupillary miosis can be an OR nightmare for the novice surgeon.
The Creation of a Capsulorhexis
Dr. Stephen LoBue and co-authors from Murrieta, California, USA, have recently published their experience with an approach that they developed and standardized in order to facilitate the creation of a capsulorhexis in patients with pupillary miosis and dense nuclear sclerosis. (Cue the sigh of great relief for cataract surgeons everywhere!)
The technique incorporates a pupil expansile ring and capsular staining under both air and dispersive viscoelastic. This stabilizes the iris and provides consistent dilation throughout the course of the case, thereby minimizing complications. The work of Dr. LoBue was originally presented at the Association for Research in Vision and Ophthalmology (ARVO 2019) in Vancouver, Canada, and more recently published in Clinical Ophthalmology.2
The nine eyes included in the report had 4+ nuclear sclerosis, absent red reflex, white mature or brunescent cataracts, accompanied by impaired preoperative pupillary dilation of 3mm or less.
Recall that the minimum threshold for successful capsulorhexis and phacoemulsification has been described as a pupil diameter of 4.5-5.0mm for experienced surgeons and 6mm for novice surgeons. These eyes were at least half of that, and some were smaller.3,4 The mechanism for miosis of patients involved in this study included posterior synechia (3), tamsulosin (2), donepezil (2) and idiopathic (1).
To illustrate how rare the presentation of this combination of dense cataract and small pupils can be, these 9 included eyes were the result of a review of 1,408 phacoemulsification cataract surgeries performed at LoBue Laser and Eye Medical Center Inc.
All patients had best corrected visual acuity (BCVA) of 20/70 or poorer. All surgeries were performed by a single experienced surgeon, and phacoemulsification was done using the Alcon Centurion platform.
A Novel Procedure
Dr. LoBue described the approach, beginning with the creation of a 1mm corneal paracentesis, superiorly for right eyes and inferiorly for left eyes. They used intracameral methylparaben-free xylocaine to numb the iris and cohesive viscoelastic to fill the anterior chamber. The cohesive viscoelastic temporarily deepens the anterior chamber, widens the pupil and supports the iris.
Using a microkeratome blade, a 2.4mm temporal clear corneal incision was made. And if posterior synechiae were present, it was broken with a collar button (a collar button was preferred in order to minimize damage to surrounding structures). Next, to adequately expand the pupil, a 6.25mm malyugin ring was placed through the self-sealing, triplaner cornea wound, docking on the nasal and superior or inferior iris. The cohesive viscoelastic was then carefully removed using an irrigating/aspiration tip, and a small amount of viscoelastic sealed the paracentesis. If necessary, the wound was sealed with a single 10-0 nylon suture before air was injected through a 27-gauge cannula through the paracentesis.
Dr. LoBue explained that surgeons shouldn’t worry if multiple bubbles appear in the anterior chamber – they will quickly coalesce into a single bubble after a few seconds. Trypan blue was then injected through the paracentesis, ensuring visualization of the cannula in the air bubble. The air and dye were subsequently removed by filling the anterior chamber with a dispersive viscoelastic.
Special importance was placed on the ability to visualize the cannula within the air bubble so as not to compromise the integrity of the anterior capsule. Finally, a ~5 mm continuous curvilinear capsulorhexis was initiated with a cystotome and was completed using Utrata forceps. [A complete explanation and illustrations of this novel approach can be found in the full article, available in Clinical Ophthalmology.2]
The authors outlined the multiple reasons that this approach is advantageous in eyes with dense cataract and small pupils: “First, the anterior segment is well sealed, minimizing air leak and shallowing of the anterior chamber during capsular staining. Rapid changes of the lens-iris plane can lead to unintentional damage of the anterior capsule, compromising capsulorhexis formation. Secondly, staining under air prevents direct contact of the dye with the corneal endothelium and allows for better enhancement of the peripheral anterior capsule rim. As a result of better visualization, the rate of successful capsulorhexis formation significantly improves.”
They added that “the uniform staining of the anterior capsule with trypan may even be helpful for all grades of cataracts, especially in training ophthalmologists”.
Promising Results
A novel technique indeed, but more importantly, how were the patient outcomes? As noted, the preoperative distance visual acuity was 20/70 or poorer, but improved from 20/20 to 20/70 in all patients, including the majority of eyes achieving an impressive 20/40 or better.
Surgery was uneventful and capsulorhexis formation was successful in all cases with no capsular tear, vitreous loss, or necessary conversion to extracapsular cataract extraction – showing promising results to improve visualization in these difficult eyes.
This approach may be beneficial in other circumstances, including high-risk cataract surgery for white mature/ deep brunescent cataracts and miosis associated with intraoperative floppy iris syndrome or for patients with a history of dementia, both associated with a high complication rate.
References:
- Martin KR, Burton RL. The phacoemulsification learning curve: per-operative complications in the first 3000 cases of an experienced surgeon. Eye (Lond). 2000;14(Pt 2):190-195.
- LoBue SA, Tailor P, LoBue TD. A Simple, Novel Approach to Capsulorhexis Formation in the Setting of A Mature Cataract and Miotic Pupil. Clin Ophthalmol. 2019;(13)2:2361-2367.
- Kim JY, Ali R, Cremers SL, Yun S-C, Henderson BA. Incidence of intraoperative complications in cataract surgery performed by left-handed residents. J Cataract Refract Surg. 2009;35(6):1019-1025.
- Malyugin B. Cataract surgery in small pupils. Indian J Ophthalmol. 2017;65(12):1323-1328.
