We appreciate the interest of Takkar and colleagues in our recent publication, “Myopic shift 5 years after IOL implantation in the Infant Aphakia Treatment Study.”1 We previously published the changes in axial length in the treated and fellow eyes for both the contact lens and intraocular lens (IOL) treated groups.2 The difference in axial length growth between treated and fellow eyes was not significant and the change in axial length between treated eyes in the contract lens and IOL groups was similar at age 5 years (CL 3.2 mm, IOL 3.4 mm). While animal studies have reported that the relative peripheral refraction affects the rate of axial growth, studies in human have failed to find this association.3–5 To the contrary, two recent studies found that the myopic shift increased when myopic children switched from spectacles to contact lenses.6,7 We have not been able to identify preoperative factors that are helpful in predicting the magnitude of the myopic shift in infantile eyes following unilateral cataract surgery and IOL implantation. This is another reason to defer implanting an IOL in an infant’s eye in addition to the higher adverse event rate associated with IOL implantation compared to aphakia.8 By deferring IOL implantation until the axial length of these eyes has stabilized, the risk of high anisometropia and an IOL exchange can potentially be adverted.
The Infant Aphakia Treatment Study (IATS) did not find a significant difference in visual acuity for infants with a unilateral congenital cataract <7 months of age who were corrected with a contact lens compared to an intraocular lens (IOL) after cataract surgery. However, there were significantly more intraoperative and postoperative adverse events and additional intraocular surgeries in the IOL group compared to the contact lens group. This outcome prompted the recommendation that IOL implantation be limited to infants at risk of experiencing “significant periods of uncorrected aphakia” if an IOL was not implanted. Some pediatric cataract surgeons have speculated that if the IATS protocol had been designed differently or if more experienced surgeons had performed the cataract surgeries that the high rate of adverse events in the IOL group would have been averted. Some of these critiques have been published as letters-to-the editor and others have been raised in forums, both public and private.3 In this report, we address these issues and, in some areas, we provide additional outcome data from the IATS to help clarify areas where there may have been misunderstandings.
Purpose To report the prevalence of anisometropia at age 5 years after unilateral intraocular lens (IOL) implantation in infants. Design Prospective randomized clinical trial. Methods Fifty-seven infants in the Infant Aphakia Treatment Study (IATS) with a unilateral cataract were randomized to IOL implantation with an initial targeted postoperative refractive error of either +8 diopters (D) (infants 28 to <48 days of age) or +6 D (infants 48–210 days of age). Anisometropia was calculated at age 5 years. Six patients were excluded from the analyses. Results Median age at cataract surgery was 2.2 months (interquartile range [IQR], 1.2, 3.5 months). The mean age at the age 5 years follow-up visit was 5.0 ± 0.1 years (range, 4.9–5.4 years). The median refractive error at the age 5 years visit of the treated eyes was −2.25 D (IQR −5.13, +0.88 D) and of the fellow eyes +1.50 D (IQR +0.88, +2.25). Median anisometropia was −3.50 D (IQR −8.25, −0.88 D); range −19.63 to +2.75 D. Patients with glaucoma in the treated eye (n = 9) had greater anisometropia (glaucoma, median −8.25 D; IQR −11.38, −5.25 D vs no glaucoma median −2.75; IQR −6.38, −0.75 D; P = .005). Conclusions The majority of pseudophakic eyes had significant anisometropia at age 5 years. Anisometropia was greater in patients that developed glaucoma. Variability in eye growth and myopic shift continue to make refractive outcomes challenging for IOL implantation during infancy.
Purpose: To report the clinical and histopathological findings associated with congenital fibrovascular pupillary membranes.
Design: Case series.
Participants: Seven infants; six with a unilateral congenital pupillary membrane and one with classic persistent fetal vasculature (PFV).
Methods: Patients underwent a membranectomy, pupilloplasty and/or a lensectomy. Histopathological examination was performed on the excised membranes.
Main Outcome Measures: Visual acuity and pupil size.
Results: Four of the 6 patients with a unilateral congenital pupillary membrane had one or more recurrences after a membranectomy and pupilloplasty. The most recent pupil size ranged from 2 to 5 mm in the affected eye. When last tested, the vision in the affected eye was excellent in 4 of the 6 patients. The two patients without recurrences of the pupillary membranes underwent multiple iris spincterotomies at the time of the initial surgery. Histopathological examination of two primary pupillary membranes showed fibrovascular tissue that did not stain for neuron specific enolase. Smooth muscle actin was only present in vascular walls. In contrast, histopathology of a recurrent pupillary membrane revealed collagenized fibrovascular tissue that was immunoreactive for smooth muscle actin. Finally, histopathology of the retrolenticular membrane excised from an infant with classic PFV was similar to the latter aside from hypercellularity.
Conclusions: Congenital fibrovascular pupillary membranes in infants are likely a variant of PFV that may recur if incompletely excised. The risk of these membranes recurring may be reduced by excising as much as the membrane as possible and enlarging the pupil with iris spincterotomies. A lensectomy should be avoided if possible.
Purpose: To report the myopic shift at 5 years of age after cataract surgery with intraocular lens (IOL) implantation for infants enrolled in the Infant Aphakia Treatment Study (IATS).
Methods: Refractions were performed at 1 month and every 3 months postoperatively until age 4 years and then at ages 4.25, 4.5, and 5 years. The change in refraction over time was estimated by linear mixed model analysis.
Results: Intraocular lens implantation was completed in 56 eyes; 43 were analyzed (median age, 2.4 months; range, 1.0–6.8 months). Exclusions included 11 patients with glaucoma, 1 patient with Stickler syndrome, and 1 patient with an IOL exchange at 8 months postoperatively. The mean rate of change in a myopic direction from 1 month after cataract surgery to age 1.5 years was 0.35 diopters (D)/month (95% confidence interval [CI], 0.29–0.40 D/month); after age 1.5 years, the mean rate of change in a myopic direction was 0.97 D/year (95% CI, 0.66–1.28 D/year). The mean refractive change was 8.97 D (95% CI, 7.25–10.68 D) at age 5 years for children 1 month of age at surgery and 7.22 D (95% CI, 5.54–8.91 D) for children 6 months of age at surgery. The mean refractive error at age 5 years was −2.53 D (95% CI, −4.05 to −1.02).
Conclusions: After IOL implantation during infancy, the rate of myopic shift occurs most rapidly during the first 1.5 years of life. Myopic shift varies substantially among patients. If the goal is emmetropia at age 5 years, then the immediate postoperative hypermetropic targets should be +10.5 D at 4 to 6 weeks and +8.50 D from 7 weeks to 6 months. However, even using these targets, it is likely that many children will require additional refractive correction given the high variability of refractive outcomes.