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Ophthalmology / Inprogress

Minimizing Difficulties in Surgical Management of Posterior Lenticonus in Children

Suqin Guo, MD · Rudolph S. Wagner, MD · Brian Forbes, MD, PhD · Anthony R. Caputo, MD
Article

Suqin Guo, MD · Rudolph S. Wagner, MD · Brian Forbes, MD, PhD · Anthony R. Caputo, MD

Introduction

Posterior lenticonus is a defect in the posterior lens capsule associated with cataracts.1 The defect of the posterior lens capsule is often a well-circumscribed, spheroidal, or conical protuberance of the posterior lens surface that can reach a diameter of 2-7 mm.2 The condition is rare, with an incidence of 1:100,000.3 However, this ratio is probably an underestimate because the posterior lenticonus can be obscured by an overlying cataract. Posterior lenticonus is diagnosed in children between the ages of 3 and 7,3 and usually occurs unilaterally and sporadically. Bilateral occurrences tend to have a familial pattern.3,4

Cataract is associated with posterior lenticonus in 80% of the patients.5 The cortex overlying the defect can develop powdery, chalk-white cataractous changes that increase in diameter and density to obscure the lenticonus, and, eventually, spread to the adjacent subcapsular cortex.6

Currently, cataract removal associated with posterior lenticonus is performed either by phacoemulsification or lensectomy techniques. A posterior capsulotomy with anterior vitrectomy is indicated in poorly cooperative patients.7 A conventional phacoemulsification/aspiration lensectomy approach can be difficult and technically challenging. During the removal of the cataract by a conventional approach, the posterior capsule can rupture and the vitreous may prolapse prematurely and anteriorly through the defect of the posterior capsule.8,9,10 Removal of the cataract along with vitreous can lead to retinal tears and/or a traction retinal detachment. The authors have developed unique surgical techniques that minimize technical difficulties and potential complications.

Surgical Techniques


SLIDE 1

Hydrodissection: Conventionally, during hydrodissection, a single continuous irrigation is used to create a large fluid wave that passes circumferentially in the zone between the cortex and the posterior capsule. Instead, in this first step, the authors use multiple, small strokes in a circular peripheral fashion to not disturb the central portion of the posterior capsule and cataract. Flipping of the cataract should be contraindicated.

Cataract removal: In the second step, the peripheral portion of the cataract is removed first. The central portion of the cataract serves as a shield and protects the defect/thin portion of the posterior capsule (Slide 1), and also prevents vitreous from mixing with the cataract during the early stage of the surgery. Once the peripheral part of the cataract is removed, the central part of the cataract is approached with low flow and low vacuum, thus exposing the central defect of the posterior capsule with minimum amount of cataract (Slide 2).

Primary posterior capsulorrhexis: The last step involves, if needed, a primary posterior capsulorrhexis over the defect of the posterior lens capsule. A primary posterior capsulorrhexis with or without an anterior vitrectomy is indicated in eyes where the defect of the posterior capsule is noted during surgery and where extensive adherence between cataract and posterior capsule is present. A limited anterior vitrectomy via a primary posterior capsulorrhexis is also performed in children who are poor candidates for future laser capsulotomy. The margin of the posterior capsulorrhexis is more stable and resistant to radial tears during anterior vitrectomy and IOL insertion. The edge of the posterior capsulorrhexis can also serve as one of the indicators of vitreous traction. If the margin of the capsulorrhexis is smooth and its shape is round, then vitreous traction is unlikely. In contrast, if notches on the margin of the capsulorrhexis exist, then vitreous traction strands should be searched for and relieved. The primary posterior capsulorrhexis with/without anterior vitrectomy may play a role in preventing and delaying the onset of secondary cataracts in children.

Results


SLIDE 2

The authors reviewed the clinical records of 47 pediatric patients who underwent cataract surgery at the University of Medicine and Dentistry of New Jersey (UMDNJ), Newark, NJ, between 1999 and 2002. We included seven consecutive patients (10 eyes) who had posterior lenticonus associated with visually significant cataracts and who underwent cataract extraction with IOL implantation using the above described surgical technique.

All eyes included in this study had a posterior lenticonus associated with a visually significant posterior capsular/polar cataract confirmed by slit-lamp biomicroscopy. Patients with other ocular abnormalities were excluded from this study. Postoperatively, patients were scheduled for follow-up after 1 week, 4 weeks, 6 months, 1 year, and yearly thereafter. No complications were encountered. The age at which patients underwent the surgery ranged from 4 to 13 years (mean was 9 years). Preoperative visual acuity ranged from 20/60 to counting fingers.

Postoperatively, at 1 week, visual acuity ranged from 20/25 to 20/60. At 1 month, 67% of patients demonstrated postoperative acuities in the 20/20 to 20/30 range and 22% of patients achieved 20/40. At 6 months, 83% of patients had a visual acuity of 20/30 or better and other patients had a visual acuity of 20/40. At 1 year, all eyes had visual acuity in the 20/20 to 20/30 range.

Discussion

Major theories exist regarding possible causes of posterior lenticonus, which include: inflammation, overgrowth of posterior lens fibers, rupture of the posterior capsule, traction exerted by a hyaloid artery remnant, and trauma. Weakness of the posterior capsule can be inherited or caused by a defect in the formation of the zonular lamellae of the capsule during and after fetal development. Another proposed mechanism is that the highly plastic epithelium of a young child's lens can herniate posteriorly with the strain of accommodation. The true etiology of the defect has yet to be elucidated.7

An extensive study reported by Cheng and colleagues7 looked at surgical intervention in patients with posterior lenticonus and recommended that early surgery be indicated to prevent visual deprivation amblyopia. Indications for surgery, as recommended by Cheng and colleagues, were a visual acuity of less than 20/70, loss of a central fixation reflex, or the onset of strabismus. At the Institute of Ophthalmology and Visual Science, Newark, NJ, a complete eye examination is conducted on all patients before cataract surgery. Once a patient is identified as having a posterior lenticonus associated with cataract, the patient's eye is carefully monitored for changes in visual acuity and cataract progression. When necessary, patients are treated with spectacle correction, including bifocals for refractive error, and occlusion therapy for amblyopia before surgery is warranted. Postoperative management includes topical antibiotics and corticosteroids for a few weeks, correction of refractive error, and aggressive treatment of ambylopia.

Surgeons should be aware of a defect or thinning of the posterior capsule when performing cataract surgery in patients with posterior lenticonus.6 These patients exhibit a high incidence of posterior capsular rupture during cataract surgery, reported at 26% rupture by Osher and colleagues8 and 36% rupture by Vasavada and Singh.9 Cataract surgery in patients with posterior lenticonus can be difficult and challenging.10 Allen and Wood1 recommended the viscodissection technique to minimize the risk of vitreous loss in patients with posterior polar cataracts. In using the approach of multiple small strokes instead of a single continuous injection during hydrodissection, the authors are able to gently separate the cortical cataract from the capsule without compromising the integrity of the central posterior capsule. In addition, by removing the peripheral part of the cataract first, the authors are able to avoid the technical difficulty of removing the cataract mixed with vitreous, therefore minimizing the potential complications associated with vitreous traction. To further ensure the strength of the posterior capsule, a primary posterior capsulorrhexis is performed in patients with posterior capsular defects and extensive adherence between the central opacity and the posterior capsule. Posterior capsulorrhexis provides a smooth and stable margin for IOL implantation and maintains its centration, allowing the surgeon to avoid vitreous and retinal traction during IOL implantation and an anterior vitrectomy when necessary. To date, none of the authors' patients had complications.

Conclusion

The techniques described in this tutorial offer better control of preexisting posterior capsule defects and easier removal of cataracts associated with posterior lenticonus. The unique surgical steps include performing multiple, peripheral strokes of hydrodissection, first cleaning the peripheral portions of cataract, and then converting the capsular defect to a primary posterior capsulorrhexis when needed. These techniques have enabled the authors to achieve consistent and excellent results and to minimize potential complications.

Slides

Slide 1. Cataract removal is initiated in the peripheral portion first. The central portion of cataract is left to serve as a shield and protect the thin/defect part of the posterior capsule.

Slide 2. After the central portion of the cataract is removed, a large central posterior capsule defect is noted and anterior vasectomy is complete.

References

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  2. Jacobs K, Meire FM. Lenticonus. Bull Soc Belge Ophthalmol. 2000; 277:65-70.
  3. Gibbs ML, Jacobs M, Wilkie AOM, Taylor D. Posterior lenticonus: Clinical patterns and genetics. J Pediatric Ophthalmol Strabismus. 1993; 30:171-175.
  4. Pollard ZF. Familial bilateral posterior lenticonus. Arch Ophthalmol. 1983; 101:1238-1240.
  5. Kralich RG, Boyce PJ. Treatment opinion for concurrent ocular disease presenting with posterior lenticonus. Optom Vis Sci. 1998; 75:468-475.
  6. Kalyanansundaram TS, Bearn MA. Surgical identification of posterior lenticonus. J Cataract Refract Surg. 2002; 28:1069-1070.
  7. Cheng KP, Hiles DA, Biglan AW, Pettapiece MC. Management of posterior lenticonus. J Pediatric Ophthalmol Strabismus. 1991; 28:143-150.
  8. Osher RH, Yu BU, Koch DD. Posterior polar cataracts: A predisposition in intraoperative posterior capsular rupture. J Cataract Refract Surg. 1990; 16:157-162.
  9. Vasavada A, Singh R. Phacoemulsification in eyes with posterior polar cataract. J Cataract Refract Surg. 1999; 25:238-245.
  10. Simons BD, Flynn HW Jr. A pars plana approach for cataract surgery in posterior lenticonus. Am J Ophthalmol. 1997; 124:695-696.