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Surodex in paediatric cataract surgery
  1. S-Y Lee1,
  2. S-P Chee1,2,3,
  3. V Balakrishnan1,2,
  4. S Farzavandi1,
  5. D T H Tan1,2,3
  1. 1Singapore National Eye Centre
  2. 2Singapore Eye Research Institute
  3. 3Department of Ophthalmology, National University of Singapore
  1. Correspondence to: Soon-Phaik Chee Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751; cheesoonphaiksnec.com.sg

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Paediatric cataract surgery is associated with a high incidence of postoperative inflammation.1–3 Intensive topical steroid therapy is still relied upon as the conventional mode of prevention and treatment.1–4 Frequently, adjuvant systemic2–5 and/or periocular steroids3–5 may be required for further control, particularly if the child has a history of, or is at risk of, uveitis (for example, microphthalmos).5–9 Non-compliance and missed application of steroid drops into the eye impedes control of the postoperative uveitis.

The Oculex Drug Delivery System (DDS; Oculex Pharmaceuticals, Inc, Sunnyvale, CA, USA) is a biodegradable device that allows sustained drug release after insertion into the anterior chamber (AC). Surodex is a DDS with 60 μg of dexamethasone incorporated into the polymer matrix (poly(lactic-glycolic)-acid, PLGA) with sustained and controlled release of dexamethasone over 7 days, achieving higher intraocular drug levels than with conventional dexamethasone eye drops.10 Randomised controlled trials found Surodex to be as effective as 0.1% dexamethasone eye drops in the control of post-cataract surgery inflammation.10–12 Surodex is approved for use in cataract surgery in Singapore.

We reviewed retrospectively all paediatric patients who underwent cataract surgery with the insertion of one pellet of Surodex into the AC at the conclusion of surgery. Eighteen eyes of 13 patients (nine males and four females) were diagnosed with cataracts at a mean age of 57.4 months (range 1 day to 136 months). The mean age at surgery was 66.5 months (range 1 week to 139 months) and follow up period ranged from 6–18 months (mean 7.8 months). Factors predisposing to cataracts included hereditary cataracts (two), microphthalmos (three), severe atopic dermatitis (one) and traumatic cataract (one). The types of cataract included total/mature (seven), nuclear (two), lamellar (three), subcapsular (two), posterior lenticonus (two), and posterior polar (two).

All eyes underwent lens aspiration through can opener anterior capsulotomy or continuous curvilinear capsulorrhexis (CCC) under general anaesthesia. Fourteen eyes had either posterior capsulotomy (with the vitrectomy cutter) or a posterior CCC (surgeon’s preference). Anterior vitrectomy was done in 13 eyes. Eleven eyes (61.1%) were implanted with a foldable intraocular lens (IOL) (Acrysof lens MA60BM, 10 and MA30BM, 1) (pseudophakic group) (Table 1). This group was older (mean 84.81 months) than the aphakic group (mean age 14.31 months). Only seven eyes (63.6%) of the pseudophakic group underwent posterior CCC/capsulotomy and anterior vitrectomy, compared to all eyes in the aphakic group. Complications were encountered in four eyes in the pseudophakic group (36.4%)—malposition of IOL, vitreous strand in AC, posterior synechiae and raised IOP.

Table 1

Pseudophakic and aphakic groups

Four eyes (two in the pseudophakic and two in the aphakic group) did not receive additional postoperative topical steroids (prednisolone acetate 1%). This decision was made for patients 4 and 12 as there was minimal manipulation and iris trauma intraoperatively. These children were older (ages 131 and 115 months at surgery), allowing for easier follow up examination. Patient 13 had developmental delay and was difficult to manage. All four eyes were assessed to be quiet by slit lamp examination 2–4 weeks postoperatively. Additional steroids were not indicated and there was no glaucoma or endophthalmitis.

One eye (patient 17) required adjuvant periocular dexamethasone (1 mg) for fibrinous inflammation in the first week. The left eye of patient 6, which had been quiescent and without treatment for 2 months, developed raised IOP (30 mm Hg) at 3 months after surgery. This was controlled with topical betaxolol. There was no glaucomatous cupping and visual fields could not be performed in view of the age of the child.

Patient 13 had severe atopic dermatitis requiring systemic prednisolone. When visually significant cataract developed in the left eye, preoperative prednisolone was increased prophylactically and a pellet of Surodex was inserted at the end of surgery. As there was minimal inflammation, the systemic steroid was tapered over 2 weeks and the steroid eye drops were stopped after 3 weeks. This eye achieved a final visual acuity of 20/20.

Comment

Fibrinous anterior uveitis is common after paediatric cataract surgery, occurring in varying severities in up to 100% of cases.2,3

In our series, only two eyes (11.1%) developed inflammation that required additional steroid therapy. The remaining 16 eyes achieved good control of inflammation, particularly the four eyes that received Surodex without postoperative topical steroids. None experienced rebound uveitis after 1 week, when the pellet had ceased its release of dexamethasone. This suggests that in selected eyes, a Surodex pellet alone may be adequate to control postoperative inflammation. A randomised controlled trial comparing Surodex versus conventional steroid eye drop therapy will be needed to determine the ultimate efficacy of Surodex in paediatric eyes.

The efficacy of eye drops is dependent on compliance and timely application for drug penetration and absorption. In infants and young children, the systemic absorption of the steroid may have potentially serious complications such as hyperglycaemia and immunosuppression. Surodex significantly reduces the total dose delivered, as the 60 μg of dexamethasone in one pellet is approximately equivalent to that in just one drop of 0.1% dexamethasone.10 A system such as the DDS allows for direct application of the drug to the target site, potentially eliminating the problems of compliance.

The single complication encountered, which may be related to Surodex insertion, is the late onset of raised IOP (patient 6) despite the lack of marked postoperative inflammation. The fellow eye had also undergone cataract surgery with insertion of Surodex without complications. Steroid responsive glaucoma is an unlikely cause as the drug has been shown to persist only for 7 days in rabbits, although this has not been demonstrated in human eyes.13 Gonioscopy may reveal focal peripheral anterior synechiae (PAS) at the site of residual pellet, but it is unlikely that this minor degree of synechiae may cause angle closure glaucoma, although the pellet may persist for weeks in the angles.10 Unfortunately, gonioscopy was not performed in this eye. Glaucoma after paediatric cataract surgery is, however, a complication that increases in frequency with longer durations of follow up (3–22%).1,5,14

We acknowledge that there are several limitations to these findings. Firstly, being a retrospective review, the efficacy of Surodex in preventing posterior capsular opacification, an indicator of postoperative inflammation, could not be assessed. We are also unable to establish if Surodex alone is sufficient for postoperative control of inflammation, this would require a prospective randomised clinical controlled trial. The efficacy of control of postoperative inflammation and safety are incomplete without the assessment of flare and endothelial cell counts but these are difficult in children, although endothelial cell count studies in adult eyes have shown no significant change.10,12 Finally, gonioscopy to visualise the angles to look for PAS was also not done.

Surodex has previously been shown to be safe and effective in uncomplicated cataract surgery in adults. This retrospective review provides preliminary data to suggest that Surodex may be an effective and safe adjunctive anti-inflammatory agent that in some paediatric eyes may eliminate the need for other steroid administration. Further studies will be required to determine the ultimate safety of Surodex in paediatric eyes.

References

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Footnotes

  • The authors have no proprietary or financial interest in Oculex Pharmaceuticals, Inc, Sunnyvale, CA, or in the product Surodex.

  • Financial support: Nil.

  • Presentation: Poster presentation at the XXIXth International Congress of Ophthalmology, Sydney, Australia. 21–25 April 2002.

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