To the Editor:
The review (
Pediatric Patient, December 2013) of the Pediatric Eye Disease Investigator Group’s (PEDIG) article misses some contradictions in the group’s reports.
A PEDIG finding was that the acuity of both the amblyopic and fellow eyes gradually improved with age prior to treatment.1 (Table 3 [Baseline Characteristics According to Age at Enrollment]). The degree of improvement with increasing age was very similar to treatment outcomes. This confirmed Clarke’s observation that “As in all trials, there is a possibility that those left untreated may suffer, but the no-treatment group in fact showed a tendency to spontaneous improvement.”2
The lack of untreated controls in most amblyopia treatment studies makes it impossible to distinguish the effects of training and increasing literacy from the presumed benefits of treatment. The PEDIG authors agree that inclusion of an untreated control group would have been desirable from a scientific point of view.3 Since “the response to treatment in this study was similar across the age range …”4 a delay in including a control group would not have incurred appreciable risk.
Spatial and temporal visual impairments are prominent features of amblyopia. Judging treatment outcomes with static and isolated optotypes may not be an optimum indicator of visual improvement. When reading ability was tested in amblyopic eyes that were successfully treated, a PEDIG study found that significant limitations were still present.5
PEDIG was formed in 1997 following a review by Snowdon and Stewart-Brown. They found “no studies of natural history of amblyopia, … no randomised controlled trials of treatment vs. no treatment …”.6 These deficiencies have still not been addressed by the PEDIG’s reports. These lapses inappropriately elevate hypotheses that are based on insufficient or irrelevant data to dogma. We cannot be certain about their conclusions until objective information is available.
The clinical environment for amblyopia is complicated by the availability of many therapies in addition to occlusion and penalization. These include, among others, forehead massage, suturing eyelids closed, perceptual learning, rotating prisms, neuroadaptation, periauricular acupuncture, vision training, levodopa-carbidopa, colored lenses, Bangerter filters, supervised near work, playing computer games and neurologic organization training. The providers of these therapies claim results that are equivalent to conventional therapies. Michael Repka, MD, [of the American Academy of Ophthalmology] warned that the Affordable Care Act may encourage overutilization of amblyopia screening and treatments. He is correct, and the lack of objective data may encourage inappropriate remedies.
It is important for our profession to develop a sound basis for the diagnosis and treatment of children presumed to have amblyopia—a basis consistent with proofs of efficacy that are consistent with therapies in other specialties, a basis that shows improvement in acuity, reading rate, and other visual functions that does not occur without that treatment. We are all familiar enough with alternative treatment to know what awaits if we fail to properly address this issue now.
Philip Lempert, MD
1. Pediatric Eye Disease Investigator Group. The clinical profile of moderate amblyopia in children younger than 7 years. Arch Ophthalmol 2002;120:281-7.
2. Clarke MP, Wright CM, Hrisos S, et al. Randomised controlled trial of treatment of unilateral visual impairment detected at preschool vision screening. BMJ 2003;327:1251.
3. The Pediatric Eye Disease Investigator Group. Amblyopia. Ocular Surgery News July 15, 2002 Page 7.
4. The Pediatric Eye Disease Investigator Group. The course of moderate amblyopia treated with patching in children: Experience of the amblyopia treatment study. Am J Ophthalmol 2003;136:620-9.
5. Repka MX, Kraker RT, Beck RW, Cotter SA, et al; Pediatric Eye Disease Investigator Group. Monocular oral reading performance after amblyopia treatment in children. Am J Ophthalmol 2008;146:942-7.
6. Snowdon S, Stewart-Brown SL. Preschool vision screening: Results of a systematic review. York: NHS centre for reviews, 1997 Report 9.