Infant Aphakia Treatment Study (IATS)

Intraocular lenses are now a commonly accepted treatment for cataracts in older children and are used increasingly in younger children and infants. Intraocular lenses are superior to contact lenses in that they more closely replicate the optics of the crystalline lens, do not require daily ongoing care, and ensure at least a partial optical correction at all times. The simplicity and improved visual outcome of an intraocular lens correction may make caring for a child with a unilateral congenital cataract less stressful for parents. However, contact lenses remain the accepted treatment for children under 1 year of age due to concerns about the long-term safety of intraocular lenses and the potential for a large myopic shift developing in these eyes as they grow. Contact lenses provide excellent visual results in infants treated for bilateral congenital cataracts; however, two-thirds of infants treated with contact lenses for unilateral congenital cataracts remain legally blind in their aphakic eye. These poor visual outcomes are usually ascribed to competition from the sound eye and poor compliance with patching and contact lens wear regimens. Data from our pilot study and the literature suggest that superior visual results can be obtained if an intraocular lens is used to correct unilateral aphakia during infancy, but these eyes will experience more complications. Intraocular lenses will be increasingly implanted in infants regardless of whether or not we perform this trial. By performing this clinical trial, we can determine if the higher rate of complications with intraocular lenses is offset by improved visual outcome and decreased parenting stress.

The Infant Aphakia Treatment Study (IATS) is a multi-center randomized clinical trial comparing intraocular lens and contact lens correction for monocular aphakia. Infants will be enrolled over a 4 year period. Infants 28 to 210 days of age with a visually significant cataract in one eye are eligible. Cataract surgery will be performed in a standardized fashion by a surgeon who has been certified for the study. Surgery consists of a lensectomy, posterior capsulotomy, and anterior vitrectomy. Infants will be randomized at the time of surgery to one of two treatment groups. Infants randomized to the intraocular lens group will have an intraocular lens implanted into the capsular bag. Spectacles will subsequently be used to correct the residual refractive errors. Infants randomized to the contact lens group will be fitted with a contact lens immediately after surgery. Both groups will receive the same patching therapy and follow-up. All children will be examined by Investigators at fixed intervals using standard protocols with the major endpoint assessed at age 12 months by a Traveling Vision Examiner.

We are currently in a continuation of this project (beyond 5 years) in order to assess which of these patients have glaucoma or glaucoma suspect at age 10.5 years. Our goal is to understand which type of initial optical correction, an IOL or a CL, results in the best long-term visual outcome following unilateral congenital cataract surgery during infancy. Our central hypothesis is that primary IOL implantation will result in a better visual outcome. The rationale for this proposal is that final visual acuity cannot be determined by 5 years of age and the recommendation for early treatment can only be substantiated by adequate long-term assessment in this unique cohort. We chose a follow-up to age 10.5 years because it will provide a more accurate assessment of visual acuity and will allow us to diagnosis most cases of glaucoma.

Inclusion criteria

• Visually significant unilateral congenital cataract (central opacity equal to or greater than 3 mm in size).
• Cataract surgery performed when the patient is 28 to 210 days of age and at least 41 post-conceptional weeks.

Exclusion criteria

• The cataract is known to be acquired from trauma or as a side-effect of a treatment administered postnatally such as radiation or medical therapy.
• A corneal diameter less than 9 mm measured in the horizontal meridian using calipers.
• An intraocular pressure of 25 mm Hg or greater in the affected eye measured with a Perkins tonometer, tonopen, or pneumatonometer.
• Persistent fetal vasculature (PFV) causing stretching of the ciliary processes or a tractional retinal detachment.
• Active uveitis or signs suggestive of a previous episode of uveitis such as posterior synechiae or keratic precipitates.
• The child is the product of a pre-term pregnancy (<36 gestational weeks). Screening for prematurity will be based on the clinician's best assessment of gestational age. If a physician is uncertain regarding the gestational age, review of medical records or contact with the pediatrician and/or obstetrician should be used to confirm gestational age at delivery. Unless a clinician is uncertain as to whether a child was born at less than 36 weeks or not, confirmation of gestational age via medical record review may be delayed until after enrollment.
• Retinal disease that may limit the visual potential of the eye such as retinopathy of prematurity.
• Previous intraocular surgery.
• Optic nerve disease that may limit the visual potential of the eye such as optic nerve hypoplasia.
• The fellow eye has ocular disease that might reduce its visual potential.
• The child has a medical condition known to limit the ability to obtain visual acuity at 12 months or 4 years of age.
• Refusal by the Parent/Legal Guardian to sign an informed consent or to be randomized to one of the two treatment groups.
• Follow-up of the child is not feasible because the child would not be able to return for regular follow-up examinations and the outcome assessments (e.g. transportation difficulties, relocation, etc.).