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Updates on surgical techniques for pediatric cataract surgery
Experts discuss the latest management techniques regarding the anterior and posterior capsules, anterior vitreous face and IOL implantation.
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Globally, congenital cataracts account for 5% to 20% of blindness in children, and these numbers differ in various countries. In the U.S., the prevalence of visually significant infantile cataract was estimated to be three or four per 10,000 live births. Congenital cataracts may involve one or both eyes and can span a wide spectrum of lens opacities, from a visually insignificant, small, focal opacity not involving the visual axis to total lens opacification. Hence, treatment strategies will vary depending on the type of lens opacity. The overall focus is to clear the visual axis in a timely fashion to prevent potential lifelong amblyopia.
Extent and location of the congenital cataract, combined with presenting age, are important factors that determine whether or not surgical intervention is indicated. If surgery can safely be delayed until eye growth stabilization has been attained and IOL implantation is appropriate, temporary nonsurgical avenues may be pursued, including pupillary dilation with tropicamide or phenylephrine; also, avoiding amblyogenic atropine may be appropriate. In selected cases, part-time occlusion may be required to prevent amblyopia. When surgical intervention is necessary, the type of procedure would be influenced by presenting age, and the surgeon should be familiar with the various complexities in the overall management of pediatric cataracts. A pediatric ophthalmologist should be an integral part of the overall team approach, along with family support, for an optimal outcome.
In this column, Drs. Vasavada, Shah and Vasavada provide a comprehensive view and a practical surgical approach in the management of pediatric cataracts.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Column
Pediatric cataract surgery is a complex issue best left to surgeons who are familiar with its long-term complications and lengthy follow-up. Cataract surgery in children is the first steppingstone in the long road to visual rehabilitation. Treatment is often tedious and difficult, requiring a dedicated team effort with the most important members of the team being the parents. Maintaining a clear visual axis while correcting the eye for a changing residual refractive error requires careful observation, sound judgment and diligent follow-up.
Surgical technique
Pediatric cataract needs a special surgical strategy because these eyes have greater elasticity of the capsule, lower scleral rigidity, higher incidence of inflammation and posterior capsule opacification, a thick vitreous gel and a small, growing eye. The surgeon should strictly adhere to the principles of the closed chamber technique, such as valvular incision, injection of ophthalmic viscosurgical devices before removing any instrument from the eye, and bimanual irrigation and aspiration.
Anterior capsule management
The anterior capsule in children is very elastic, and therefore it may be difficult to perform a controlled manual continuous curvilinear capsulorrhexis (CCC). However, a manual CCC is the gold standard in terms of maintaining the integrity of the capsular edge. The shape, size and edge integrity of the anterior capsulotomy are important for long-term centration of the IOL. Capsulorrhexis is usually performed with microrhexis forceps (Figure 1). Alternative techniques to manual CCC include vitrectorhexis, radiofrequency diathermy with a Fugo plasma blade, the two-incision push-pull technique and the four-incision technique.
Images: Vasavada AR, Shah S, Vasavada V
Management of posterior capsule, anterior vitreous face
The most frequent and significant problem after pediatric cataract surgery is visual axis opacification. The younger the child, the higher the incidence and the earlier the onset of visual axis opacification. Maintenance of a clear visual axis remains a high priority when planning management of the posterior capsule in the amblyogenic age range. Posterior capsulotomy can be performed with various approaches including manual posterior continuous curvilinear capsulorrhexis (PCCC), vitrectorhexis, radiofrequency diathermy and Fugo plasma blade. Manual PCCC is performed before IOL implantation, whereas if a pars plana vitrectorhexis is performed, it is done after the IOL is implanted.
PCCC alone may delay the onset of visual axis opacification but cannot eliminate it completely. The anterior vitreous face may act as a scaffold for the proliferating lens epithelial cells. Moreover, because the inflammatory response in small children is severe, fibrous membranes may form on the intact anterior vitreous face, resulting in visual axis opacification. Hence, anterior vitrectomy along with posterior capsulotomy is advocated in infants and children younger than 6 to 7 years of age. Most surgeons prefer manual anterior limbal vitrectomy over pars plana vitrectomy. The adequacy of anterior vitrectomy may be confirmed by injecting triamcinolone to aid visualization of the vitreous. We have described a technique to render the vitreous visible and ensure a thorough, complete anterior vitrectomy in pediatric cataract surgery after a manual PCCC with or without IOL implantation using preservative-free triamcinolone acetonide (Figure 2).
We have stratified posterior capsule management according to the age of the child. Children younger than 3 years are subjected to PCCC and anterior vitrectomy. Children between 3 and 6 years are subjected to PCCC but no vitrectomy. In children older than 6 years, PCCC is not performed (Figure 3).
IOL implantation
Options for optical correction after pediatric cataract surgery are primary IOL implantation, aphakic glasses and contact lenses. Primary IOL implantation has become a preferred approach in children older than 2 years. IOL implantation is still controversial in children younger than 2 years, especially those younger than 1 year, because the safety of IOL implantation in these eyes is not proven. Eyes with juvenile rheumatoid arthritis, microcornea, microphthalmos and severe persistent fetal vasculature may be considered as contraindications for IOL implantation.
IOL implantation in children has the benefit of providing at least partial optical correction that aids in visual development, especially in eyes prone to amblyopia. For bilateral cataract during this first year, aphakic glasses and/or contact lens use may be a reasonable option. We have conducted a randomized clinical trial to compare the severity of complications and visual outcomes in children up to 2 years with bilateral cataracts undergoing cataract surgery with or without IOL implantation. At the 5-year postoperative follow-up, there was a higher incidence of secondary glaucoma in aphakic patients, while there was a higher incidence of posterior synechiae and visual axis opacification in pseudophakic patients. IOL implantation achieved better visual outcomes. However, for unilateral cataract, it is still controversial whether to offer primary IOL implantation at the time of infantile cataract surgery.
Both PMMA and hydrophobic acrylic foldable IOLs have been widely used in pediatric eyes. However, several studies have now shown that hydrophobic acrylic IOLs are preferable because they offer better uveal biocompatibility and decreased incidence of visual axis opacification, with hydrophobic acrylic IOLs causing a delayed onset of posterior capsule opacification. In-the-bag fixation is the most preferred site of IOL implantation, although the IOL may also be implanted in the ciliary sulcus in cases of inadequate posterior capsular support.
Newer approaches
Bag-in-the-lens implantation: Tassignon and colleagues reported the outcome of a surgical procedure they called “bag-in-the-lens” in pediatric cataractous eyes. In this technique, the anterior and posterior capsules are placed in the groove of a specially designed IOL, after a capsulorrhexis of the same size is created in both capsules. The principle behind this IOL design is to ensure a clear visual axis by mechanically tucking the two capsules into the IOL, thereby preventing any migration of proliferating lens epithelial cells.
Posterior capsulorrhexis combined with optic buttonholing: Recently, Menapace introduced posterior optic buttonholing, a safe and effective technique that not only excludes retro-optical opacification, but also withholds capsular fibrosis by obviating direct contact between the anterior capsular leaf and the optic surface.
Summary
While dramatic advances have occurred in this field over the past 10 years, some technical aspects of surgery, changing refraction and functional outcome continue to pose significant problems. Primary management of the posterior capsule is mandatory depending on the age of the child at the time of surgery. With refinements in surgical techniques, improvements in IOLs and better understanding of growth of the pediatric eye, in the coming years, IOL implantation is likely to become an established mode of treatment of children even in the youngest age group.
- References:
- Foster A, et al. J Cataract Refract Surg. 1997;doi:10.1016/S0886-3350(97)80040-5.
- Holmes JM, et al. Ophthalmic Epidemiol. 2003;doi:10.1076/opep.10.2.67.13894.
- Infant Aphakia Treatment Study Group, et al. Arch Ophthalmol. 2010;doi:10.1001/archophthalmol.2010.101.
- Plager DA, et al. Am J Ophthalmol. 2014;doi:10.1016/j.ajo.2014.07.031.
- Vasavada A, et al. J Cataract Refract Surg. 1997;doi:10.1016/S0886-3350(97)80048-X.
- Vasavada AR, et al. J Cataract Refract Surg. 2011;doi:10.1016/j.jcrs.2010.10.036.
- For more information:
- Abhay R. Vasavada, MS, FRCS, can be reached at Iladevi Cataract & IOL Research Center, Raghudeep Eye Hospital, Gurukul Road, Memnagar, Ahmedabad, India; email: icirc@abhayvasavada.com.
- Edited by Thomas “TJ” John, MD, a clinical associate professor at Loyola University at Chicago and in private practice in oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at tjcornea@gmail.com.
Disclosure: Vasavada and John report no relevant financial disclosures.