Managing Unexpected Zonular Instability in Traumatic Cataract

This case was complicated by unexpected, profound zonular instability, necessitating intraoperative conversion from planned extracapsular cataract extraction with phacoemulsification to intracapsular cataract extraction with anterior vitrectomy and anterior chamber intraocular lens (ACIOL) placement using a Sheets glide. This conversion reflects appropriate real-time surgical decision-making in response to inadequate capsular support and highlights one of several accepted strategies for managing severe zonular compromise encountered intraoperatively.

The indication for surgery was a hypermature cataract of the left eye resulting in significantly reduced visual acuity. Intraoperatively, extensive zonular loss rendered the capsular bag unsafe for continued phacoemulsification or standard extracapsular techniques. Intracapsular cataract extraction was therefore required, followed by anterior vitrectomy to address vitreous prolapse into the anterior chamber and enable safe secondary lens implantation.

In eyes with adequate zonular support, extracapsular cataract extraction with phacoemulsification is preferred due to lower complication rates and preservation of the posterior capsule. Intracapsular cataract extraction is not appropriate when capsular support is sufficient or in patients who are poor surgical candidates due to systemic instability or coexisting ocular pathology that precludes safe intervention.

Iris retractors were employed to achieve adequate pupil expansion in the setting of poor pharmacologic dilation. Capsular staining with trypan blue was used to enhance visualization in the presence of a hypermature cataract and poor red reflex. Given the high likelihood of capsular instability, backup instrumentation for intracapsular extraction, anterior vitrectomy, and ACIOL placement was prepared and immediately available. Additional instruments including a lens loop, anterior vitrectomy, anterior chamber intraocular lens, and Sheets glide were readily available.

Preoperative evaluation included best-corrected visual acuity, pupillary examination, intraocular pressure measurement, and slit-lamp examination, which demonstrated an advanced cataract in the left eye. Visualization of the posterior segment was not possible, limiting assessment for underlying retinal pathology. However, absence of a relative afferent pupillary defect suggested preserved optic nerve function and reasonable visual potential.

Intraoperatively, inferior zonular absence spanning approximately five clock hours was identified, resulting in significant lens instability. Due to the inability to safely preserve the capsular bag, the planned extracapsular approach was converted to intracapsular cataract extraction, followed by anterior vitrectomy and anterior chamber intraocular lens placement.

Intracapsular cataract extraction allows for complete lens removal in cases of severe zonular insufficiency where capsular preservation is unsafe or impossible. However, extracapsular techniques are preferred when feasible due to preservation of the posterior capsule and lower rates of vitreoretinal complications. Furthermore, an anterior chamber lens was placed in this case with the advantages of reliability in an unstable case, no scleral sutures, and predictable refractive outcomes. Other alternatives that one may consider include leaving the patient aphakic, scleral sutured posterior chamber IOL placement, or a suture less intrascleral fixation such as the Yamane method.

Intracapsular cataract extraction carries an increased risk of vitreous prolapse, vitreoretinal traction, retinal detachment, cystoid macular edema, endophthalmitis, corneal decompensation, secondary glaucoma, and aphakia. These risks were mitigated through controlled use of viscoelastic agents and prompt, thorough anterior vitrectomy to relieve vitreous traction and stabilize the anterior segment. Anterior chamber intraocular lens placement is associated with risks including chronic endothelial cell loss, secondary glaucoma, and uveitis–glaucoma–hyphema (UGH) syndrome. To minimize these risks, careful assessment confirmed adequate anterior chamber depth, healthy corneal endothelium, and normal angle anatomy prior to lens implantation.

The authors report no financial or institutional conflicts of interest related to this case.

The authors acknowledge the surgical team, anesthesia staff, and clinical personnel involved in the care of this patient.

1. Shen JF, Deng S, Hammersmith KM, et al. Intraocular lens implantation in the absence of zonular support: an outcomes and safety update: a report by the American Academy of Ophthalmology. Ophthalmology. 2020;127(9):1234–1258. doi:10.1016/j.ophtha.2020.03.005. https://pubmed.ncbi.nlm.nih.gov/32507620/ This American Academy of Ophthalmology report reviews surgical options for intraocular lens implantation when zonular or capsular support is inadequate, including anterior chamber intraocular lenses, scleral-sutured lenses, and sutureless fixation techniques. The report supports anterior chamber intraocular lens placement as an accepted and appropriate option following anterior vitrectomy when capsular support is not sufficient to safely proceed with extracapsular techniques. 2. Zhang C, et al. Clinical outcomes of scleral fixation secondary intraocular lens with Yamane versus suture techniques: a systematic review and meta-analysis. https://pubmed.ncbi.nlm.nih.gov/38892783/ This systematic review and meta-analysis compares outcomes of sutureless Yamane fixation and traditional scleral-sutured posterior chamber intraocular lenses in eyes lacking capsular support. While focused on posterior fixation methods, the study highlights that multiple accepted strategies exist for secondary intraocular lens placement, reinforcing that intraoperative lens selection should be individualized based on anatomical stability and surgical context. 3. Wagoner MD, Cox TA, Ariyasu RG, Jacobs DS, Karp CL. Intraocular lens implantation in the absence of capsular support: a comparison of anterior chamber and sutured posterior chamber intraocular lenses. Am J Ophthalmol. 2003;136(6):1107–1114. https://pubmed.ncbi.nlm.nih.gov/15975454/ This comparative study evaluates outcomes of anterior chamber versus sutured posterior chamber intraocular lenses in eyes without capsular support following complicated cataract surgery. The results demonstrate that anterior chamber intraocular lenses can achieve comparable visual outcomes, supporting their use as a reasonable and effective option when zonular instability necessitates conversion away from extracapsular cataract extraction.