Options for pediatric cataract surgery continue to improve

H. Burkhard Dick

As a result of continuous improvements in surgical techniques and IOL composition and design, pediatric cataract surgery and outcomes have improved dramatically in the last 20 years.

If the cataract is visually significant, surgery should be carried out as soon as possible. In the cover story in this issue, Dr. Dimple Prakash points out measures to diagnose cataract in children as early as possible, which is still a challenge in some countries.

Pediatric cataract management requires an individualized approach with a specific skill set and highly trained team. Therefore, I think that a well-trained anterior segment surgeon should perform the surgery and a pediatric ophthalmologist specializing in contact lens care should conduct the carefully monitored follow-up care.

Most congenital cataracts are familial or idiopathic, whereas metabolic disorders or ocular abnormalities are rare. Timing and choice of treatment are crucial for subsequent visual rehabilitation. Postoperatively, the proliferation of lens epithelial cells may induce visual obscuration. The highly elastic iris predisposes to iridocorneal adhesions, iris capture and pupillary distortion. The most prominent postoperative problem is posterior capsular opacification.

Primary intraoperative posterior capsule removal, preferably using posterior continuous curvilinear capsulorrhexis (PCCC), is regarded as mandatory in children 10 years and younger by the majority of pediatric cataract surgeons.

Preoperative examination

A careful preoperative examination of the eyes is essential. Direct ophthalmoscopy first assesses the red light reflex in an undilated pupil. It is advisable to postpone surgery until the child is older in case of an expected normal visual development.

An intraoperative situs of a pediatric eye with cataract after staining with trypan blue. Staining was performed to improve visibility and reduce the elasticity of the capsule. Image: Dick HB

Complete examinations with both eyes dilated to detect malformations in the non-cataract eye often require general anesthesia followed by surgery. Anterior segment examination and measurement of IOP, corneal curvature and axial length are carried out for contact lens or IOL power calculation. If possible, indirect ophthalmoscopy is necessary to exclude posterior segment abnormalities that might affect visual outcome.

Choice of surgical technique

Bilateral simultaneous surgery has become increasingly popular in infants with bilateral cataracts. Each surgery is performed as a separate procedure, including new draping and change of instrumentation, tubes, gloves and clothes.

According to a study by Saini and colleagues, “In cases of pediatric cataract, staining the anterior and posterior capsules with trypan blue 0.1% allowed recognition of capsule flaps and facilitated the creation of complete ACCCs [91.3%] and PCCCs [82.6%].”

In our own study, trypan blue staining affected the biomechanical properties of the human lens capsule and led to a significant reduction in elasticity and an increase in stiffness. Other surgeons use a vitrectomy-created capsulotomy, which is useful in children 2 years and younger.

PCCC is not an indicator of a clear visual axis result. The anterior vitreous face can become a scaffold for metaplastic lens epithelial cells, which leads to visual axis opacification. Optic capture through the PCCC without vitrectomy did not prevent opacification and, therefore, is less popular among pediatric surgeons.

Using a viscoadaptive ophthalmic viscosurgical device (OVD), I personally prefer implantation of a modified closed foldable capsular ring (CFCR, Morcher) as well as an acrylic hydrophobic foldable IOL with a sharp optic edge design in the capsular bag. The CFCR consist of eight hydrophobic and eight hydrophilic ring segments and is available in different diameters. As I wrote in my study, all operated eyes demonstrated a low postoperative inflammatory reaction and a clinically well-centered IOL. The band-shaped, sharp-edged CFCR facilitates the creation of a sharp, continuous bend in the equatorial capsule, which prevents fusion of the anterior capsule with the posterior capsule. It permanently keeps the capsular bag open for secondary lens implantation or later IOL exchange. Combining the OVD and the CFCR enhances the safety of primary and secondary posterior chamber IOL implantation in pediatric cataract surgery, reduces capsule opacification and facilitates IOL exchange.

IOL power, type

Many surgeons are reluctant to implant an IOL in patients with microphthalmia, persistent hyperplastic primary vitreous with ocular abnormalities and active juvenile rheumatoid arthritis. In case of aphakia, a contact lens is best fitted directly on the operating table.

The pediatric eye is unique to the adult eye in many aspects. The different anatomy of children’s eyes includes steeper cornea, shallower anterior chamber and shorter axial length, all of which affect IOL calculation, Lin and Buckley reported in a study. The appropriate lens power proves challenging to choose because of the constantly changing refraction, they said. Because biometry and IOL calculations are less reliable under the age of 2 years, aiming for an initial slight undercorrection theoretically provides more flexibility over time.

In children older than 2 years, IOL implantation is generally considered. In children younger than 2 years, most surgeons do not implant an IOL. To the best of my knowledge, no study to date has compared the visual outcomes and adverse events of contact lens with primary IOL correction of monocular aphakia during infancy.

In this issue, Dr. Wilson reports the first study results of the Infant Aphakia Treatment Study Group. The study group concluded that until longer-term follow-up data are available, caution should be exercised when performing IOL implantation in children 6 months or younger.

Several studies demonstrated satisfactory results after implantation of foldable hydrophobic acrylic IOLs, which is the IOL of choice in pediatric cataract surgery. A hydrophilic IOL may demonstrate insufficient capsular bag performance in pediatric eyes. Because of the lower tackiness and stiffness of hydrophilic IOL material to the anterior and posterior capsule compared with hydrophobic IOLs, there is a greater chance of IOL decentration, excessive capsule contraction and anterior opacification.

The promising bag-in-the-lens implantation technique introduced by Dr. Marie-José Tassignon might especially profit from the upcoming increased use of femtosecond laser technology for a perfect capsulorrhexis in cataract surgery. That could possibly improve acceptance and safety to keep the visual axis clear after cataract removal.

Bifocal lenses offer an appealing option for aphakic or pseudophakic eyes. Especially in the older age group, these eyes respond well to a multifocal IOL, especially the diffractive optics in small pupils. There has been no consensus or sufficient research to justify routine use of multifocal IOLs in pediatric cataract surgery.

Conclusion

Because of all the surgical challenges and the relatively low incidence of pediatric cataract, the postoperative care ideally is centralized. The routine use of highly viscous OVDs, anterior and posterior continuous curvilinear capsulorrhexis, in-the-bag or bag-in-the-lens implantation and modern-design foldable acrylic IOLs significantly improves outcomes in pediatric cataract surgery.

References:

• Dick HB. Closed foldable capsular rings. J Cataract Refract Surg. 2005;31(3):467-471.
• Dick HB, Aliyeva SE, Hengerer F. Effect of trypan blue on the elasticity of the human anterior lens capsule. J Cataract Refract Surg. 2008;34(8):1367-1373.
• Dick HB, Schwenn O, Pfeiffer N. Implantation of the modified endocapsular bending ring in pediatric cataract surgery using a viscoadaptive viscoelastic agent. J Cataract Refract Surg. 1999;25(11):1432-1436.
• Infant Aphakia Treatment Study Group, Lambert SR, Buckley EG, Drews-Botsch C, et al. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol. 2010;128(7):810-818.
• Kurz S, Krummenauer F, Dumbach C, Pfeiffer N, Dick HB. Effect of a closed foldable equator ring on capsular bag shrinkage in cataract surgery. J Cataract Refract Surg. 2006;32(10):1615-1620.
• Lin AA, Buckley EG. Update on pediatric cataract surgery and intraocular lens implantation. Curr Opin Ophthalmol. 2010;21(1):55-59.
• Saini JS, Jain AK, Sukhija J, Gupta P, Saroha V. Anterior and posterior capsulorhexis in pediatric cataract surgery with or without trypan blue dye. J Cataract Refract Surg. 2003;29(9):1733-1737.
• Tassignon MJ, De Veuster I, Godts D, Kosec D, Van den Dooren K, Gobin L. Bag-in-the-lens intraocular lens implantation in the pediatric eye. J Cataract Refract Surg. 2007;33(4):611-617.

• H. Burkhard Dick, MD, can be reached at University Eye Clinic, University of Bochum, In der Schornau 23-25, 44892 Bochum, Germany; +49-234-299-3101; email: burkhard.dick@kk-bochum.de.
• Disclosure: Dr. Dick holds part of a patent on the closed foldable capsular ring from Morcher.