ASCRS News: ASCRS/EyeWorld Journal Club
July 2021

by Saira Khanna, MD, Shivam Amin, MD, Lindsay Chun, MD, Farida Hakim, MD, Jacob Kanter, MD, Zhuangjun Si, MD, Peter Veldman, MD

Iatrogenic iris defects are a common complication of cataract surgery that can negatively impact the visual function of patients. The complication rate has been reported to be 0.55–1.1%.^1,2 Patients can experience debilitating glare, halos, or have significant cosmetic concerns that may require surgical intervention.³ Iris defects can be classified according to anatomic layer, size, and location and will impact the decision and type of repair. Because of the frequency, understanding how to minimize and manage iris defects is imperative for cataract surgeons. The authors comprehensively described not only how to approach patients to avoid iatrogenic iris trauma but also various techniques to address iris defects preoperatively, intraoperatively, and postoperatively.

Summary

The iris can be damaged during phacoemulsification in a myriad of ways: prolapsing through the wound, being aspirated through the handpiece, mechanical chafing with a chopper or lens fragment, as well as generalized damage from ultrasound energy, with a small pupil being the most common risk factor. The authors discussed the risk factors for inadequate dilation including senile miosis, posterior synechiae, pseudoexfoliation, and systemic medications, most commonly alpha-1a adrenergic antagonists, which also cause intraoperative floppy iris syndrome (IFIS). Thorough preoperative review for these risk factors, discontinuation of miotic agents, ophthalmic viscosurgical devices, and additional mydriatics or preoperative NSAID use to maintain intraoperative dilation are potential pharmacologic recommended strategies. 

Surgical strategies to protect the iris include attention to fluidics and wound construction to prevent anterior chamber turbulence and iris prolapse. The authors also discussed techniques for the enlargement of small pupils including stretch pupilloplasty with Kuglen hooks and Vannas scissors and the insertion of devices such as iris hooks and pupil expansion rings.

If an iris defect does occur, the authors recommended that during surgery the surgeon first inspect the location and extent of an iris defect to gauge whether it will be visually significant and determine whether to repair immediately or in a subsequent surgery. The advantages of immediate repair include limiting potential visual symptoms, improved cosmesis, and avoidance of future scarring. Delaying repair can allow the surgeon to gauge whether a defect is visually significant enough to warrant repair. Alternatives such as prosthetic contact lenses, corneal tattooing, or topical pilocarpine can be explored. Topical NSAIDs and corticosteroids may be used in the interim to prevent excess inflammation from injured iris tissue.  

If proceeding with surgical repair, the authors stated the importance of selecting the appropriate modality of sedation and anesthetic and paying attention to which area of the iris is affected. The authors discussed that focal iris sphincter damage repair involves passing sutures through underactive iris and approximating it such that the radiality of the iris is achieved. In cases of diffuse sphincter damage, they recommended an iris cerclage technique wherein multiple paracentesis openings are used to access the iris and pass basting or whip stitches evenly spaced along the pupil margin and tied with an intraocular knot to produce a smooth, round pupil. 

Mid-peripheral iris defects may be repaired by passing sutures through undamaged iris tissue on either side of the defect; larger mid-peripheral defects may require multiple sutures placed along the length of the defect. The authors offered two approaches to iridodialysis damage repair: placement of mattress sutures through the peripheral edge of the iris defect and scleral wall or the sewing machine technique. Iris cautery is discussed as a method of reshaping the pupil with 25-gauge intraocular diathermy at the pupillary margin to cause contraction of iris collagen with care to avoid over-cauterizing the iris sphincter. In cases where there is extensive iris damage or friable iris tissue that make primary surgical repair unfeasible, the authors suggested iris prosthetics.

The authors discussed intraocular knots that can be used to suture iris tissue. They discussed the forces that comprise a knot’s holding strength: internal friction (suture on suture from multiple throws) and external friction (from the surrounding iris); they stated that a 2-1-1 configuration strikes the right balance between security and ease with which it can be pulled into the eye. The authors then detailed the Siepser knot and several of its variations. These include the Osher-Cionni-Snyder, Condon, Ahmed, and Narang-Agarwal variants, which differ in their means of tying, but all involve externalizing the throws and pulling to tighten over the iris. The authors discussed the Ogawa knot and the Ahmed variant, which are similar to the Siepser in that the knot is formed outside the eye but differ in their use of an IOL manipulator to slide the knot onto the iris. They also mentioned the Ahmed 2-intraocular forceps knot, which is the only knot to be performed entirely within the anterior chamber. 

Discussion

The authors provided an excellent overview of risk factors for iris injury due to a small pupil, along with various pharmacological options for enhancing dilation. The literature largely supports intracameral use of medications over topical dilating drops alone, especially for patients who are at risk for IFIS. Wilson et al. looked at the need for pupil expansion devices (PED) with topical versus intracameral dilation and found that intracameral dilation significantly decreased the need for PED use, especially in patients on tamsulosin.⁴ In addition to cost-saving benefits, there was presumably less iris manipulation/injury in cases not requiring PEDs. A small randomized controlled trial showed that there was less iris prolapse and billowing in patients on tamsulosin who received phenylephrine and ketorolac in the irrigation solution compared to those who received balanced salt solution alone.⁵ The authors do not mention Mydriasert (Thea Pharmaceuticals), a tropicamide/phenylephrine pill-like implant that is inserted in the inferior fornix. One study compared a cocktail of intracameral tropicamide, phenylephrine, and lidocaine vs. Mydriasert and found that the implant provided almost an additional millimeter of dilation.⁶

In discussion of surgical strategies, the authors’ attention to fluidics and wound construction is particularly useful for surgeons early in their training. There may be a temptation to use continuous irrigation for ease of maintaining the anterior chamber stability. However, irrigation while exiting the wound may promote iris prolapse. One discussant suggested that if iris prolapse due to an unstable wound occurs more than once during a case, the surgeon may consider closing the wound with sutures and creating a better incision elsewhere to reduce risk of iris injury during the rest of the case. In the discussion of methods for pupil enlargement, the authors described the advantages and disadvantages of each technique. Iris hooks increase surgical time compared to pupil expansion rings but are more versatile intraoperatively. Pupil expansion rings have also been associated with higher rates of postoperative corneal edema and uveitis.⁷ 

The authors provided a helpful overview of the complexities involved in the difficult decision of whether to repair an iris defect caused during cataract surgery. In addition to gauging the potential visual significance and cosmesis of a given iris defect, the surgeon must consider the timing of surgical repair and his/her comfort level. The authors mentioned alternatives to surgical repair for cosmetically undesirable or visually significant iris defects. Keratopigmentation is an effective alternative to intraocular surgery. In a case series, 11 patients with moderate to severe visual dysfunction from iris defects and pupil abnormalities underwent manual intralamellar or femtosecond-assisted keratopigmentation with marked improvement in symptoms and acceptable cosmesis in all 11 patients.⁸ Furthermore, newer micronized mineral pigments have been shown to be non-toxic to the cornea.⁹ Keratopigmentation may be an effective alternative to avoid a second intraocular surgery in larger, more complex iatrogenic iris defects.

The authors offered a systematic approach to the examination of the iris based on location and extent of the defect. While the options of iris repair are helpful to have in the surgeon’s arsenal, it would also be important to consider the comparative safety profiles of the different techniques of iris repair. In a study of 50 eyes that underwent iridodialysis repair, Wan et al. demonstrated that eyes that underwent either hypodermic needle-guided suturing or double-armed suturing achieved similar outcomes of improvement in visual acuity, intraocular pressure, round pupil shape, and endothelial cell count by 6 months.¹⁰ However, there are no multicenter and adequately powered studies that compare long-term functional outcomes, cost-effectiveness, and accessibility of the different iris repair techniques. The trends in the long-term implications of different iris repair strategies would require stratification based on the etiologies that underlie iris defects, whether they be congenital, traumatic, or iatrogenic, and the effects by co-occurring complications on outcomes of iris repairs. 

The choice of technique should be informed with a systematic consideration of the associated risks to the patient. It would also be helpful to plan for surgical repair in cases of multiple types of iris defects; for example, if there was a case of simultaneous iridodialysis and sphincter damage, it may not be obvious which defect to first address. 

The section on intraocular knots is a useful overview, but a more detailed discussion with respect to the benefits and drawbacks of the various categories of knots would be welcome. A similar published review had a more narrow scope but dove deeper into the historical context of these various knots and their relative utility.¹¹ Importantly, though the Siepser knot spares the iris potential traction induced trauma compared to the McCannel knot, many of the variations on the Siepser were published due to its technical difficulty.¹² Furthermore, other variants have been published that are useful in specific settings. There is a Siepser modification in which the knot lies posterior to the iris, which is useful in concomitant corneal transplants.¹³ 

Overall, this review is a thorough summary of how to approach iatrogenic iris defects. It is a helpful overview for all cataract surgeons, but especially for those in the early stages of their surgical careers. 

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Management of common iatrogenic iris defects induced by cataract surgery

Gary Foster, MD, Brandon Ayres, MD, Nicole Fram, MD, Sumitra Khandewal, MD, Gregory Ogawa, MD, Susan MacDonald, MD, Kevin Miller, MD, Michael Snyder, MD, Abhay Vasavada, MD
J Cataract Refract Surg. 2021;47(4):522–532

The proximity of the iris to the instruments and currents of cataract surgery makes iatrogenic damage to the iris a common complication of cataract surgery. This paper discusses techniques to prevent or minimize this damage. When damage does occur, the surgeon must decide if, when, and how to repair the damage. Principles governing these decisions and techniques for repair are discussed. Figures and videos, included as online Supplemental Data files, illustrate cases of iatrogenic damage and repair techniques.

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References

1. Syed ZA, et al. Cataract surgery outcomes at a UK independent sector treatment centre. Br J Ophthalmol. 2015;99:1460–1465. 
2. Norregaard JC. Results from the International Cataract Surgery Outcomes Study. Acta Ophthalmol Scand. 2007;85:5–32. 
3. Dunn SP, Stec L. Iris Reconstruction. In: Macsai, MS (Ed.). Ophthalmic Microsurgical Suturing Techniques. Springer Berlin Heidelberg. 2007:71–83. 
4. Wilson CW, et al. Pupil expansion device use and operative outcomes with topical dilation vs intracameral epinephrine in resident-performed cataract surgery. J Cataract Refract Surg. 2020;46:562–566. 
5. Silverstein SM, et al. Effect of phenylephrine 1.0%–ketorolac 0.3% injection on tamsulosin- associated intraoperative floppy-iris syndrome. J Cataract Refract Surg. 2018;44:1103–1108. 
6. de Faria A, et al. Same-eye comparison of pupillary dilation with an intraoperative standardized intracameral combination of mydriatics (Mydrane®) versus a preoperative ophthalmic (Mydriasert®) in standard cataract surgery in non-diabetic patients. J Fr Ophtalmol. 2019;42:e339–e348.
7. Nderitu P, Ursell P. Iris hooks versus a pupil expansion ring: Operating times, complications, and visual acuity outcomes in small pupil cases. J Cataract Refract Surg. 2019;45:167–173. 
8. Alio JL, et al. Keratopigmentation (corneal tattooing) for the management of visual disabilities of the eye related to iris defects. Br J Ophthalmol. 2011;95:1397–1401. 
9. Amesty MA, et al. Corneal tolerance to micronised mineral pigments for keratopigmentation. Br J Ophthalmol. 2014;98:1756–1760. 
10. Wan W, et al. Comparing safety and efficiency of two closed-chamber techniques for iridodialysis repair – a retrospective clinical study. BMC Ophthalmol. 2018;18:311. 
11. Lian RR, et al. Iris reconstruction suturing techniques. Curr Opin Ophthalmol. 2020;31:43–49. 
12. Osher RH, et al. Modification of the Siepser slip-knot technique. J Cataract Refract Surg. 2005;31:1098–1100. 
13. Schoenberg ED, Price FW. Modification of Siepser sliding suture technique for iris repair and endothelial keratoplasty. J Cataract Refract Surg. 2014;40:705–708.

Contact 

Khanna: Saira.Khanna@uchospitals.edu
Veldman: pveldman@bsd.uchicago.edu