Visual correction in childhood aphakia

How common is it?

In developed countries, congenital cataract occurs at a frequency of 0.3 – 0.9%, whilst this complication represents the main cause of potential visual loss in childhood in less developed countries. Overall, the congenital cataract and cataract in childhood - both bilateral and unilateral - lead to distinct visual deprivation.

Dense congenital cataracts and childhood trauma invariably lead to deprivational amblyopia in childhood, with IOL implantation and/or a prescription of binocular or progressive glasses being the current recommendation in children over the age of two years. In order to achieve good functional results, however, early surgical treatment and occlusion therapy are essential to prevent the development of amblyopia in this patient population. In my opinion, orthoptic control, regular check-ups and correction of refractive errors by skiaskopy are mandatory aspects of treatment.

How should we be treating it?

Glasses present a feasible option for the correction of refractive errors in children; however, they are only effective in children with bilateral aphakia, and drawbacks include the weight and the cosmetic appearance of the glasses, prismatic distortion and visual field constriction. Currently, contact lenses are most frequently recommended for visual correction of childhood aphakia. These should be fitted immediately after cataract surgery ensuring refraction is adapted to the action range of the infant (approximately arm's length). Regular six to 12 month check-ups are also advisable because of eyeball growth and accompanying alterations in lens power.

In my opinion, IOL implantation should also be considered in children over the age of two years.

When considering monofocal IOLs, power calculation of the lenses should be done in the range of hyperopia with compensation by glasses or piggyback IOL implantation. IOLs > 40 D are generally required in order to achieve "playing distance" vision (approximately 30 cm).

Second generation multifocal IOLs, like the ReZoom IOL (AMO), are a good alternative to the monofocal lenses because they are associated with greater steroptic, uncorrected and distance-corrected visual outcomes. Furthermore, visual performance after lensectomy is better in eyes that had been treated for bilateral cataracts compared with unilateral cataracts with the multifocal lenses.

In the past, IOLs were considered as a good alternative for the treatment of unilateral cataract; however, postoperative irritations and the issues relating to eyeball growth have hindered their widespread use. Today, IOL implantation is a feasible treatment option for visual rehabilitation in congenital cataract, particularly in older children. Many studies have certainly advocated the use of the multifocal IOLs in this patient population^1-6 and, although contact lenses present an adequate treatment approach, especially in the younger child, employment of the new generation of multifocal lenses when dealing with these cases should be carefully considered.

Klaus Weber is an ophthalmic consultant based in Mannheim, Germany. He indicates no financial interest in any product mentioned herein. He can be reached by E-mail: dr.k.weber@gmx.de

References

1. W. Schrader, H. Witschel. Ophthalmologe 1994 91:490-97.

2. P.C. Jacobi, et al. Ophthalmology 2001 108:1375-1380.