Efficiency of electronically monitored amblyopia treatment between 5 and 16years of age: New insight into declining susceptibility of the visual system

Abstract

The notion of a limited, early period of plasticity of the visual system has been challenged by more recent research demonstrating functional enhancement even into adulthood. In amblyopia ("lazy eye") it is still unclear to what extent the reduced effect of treatment after early childhood is due to declining plasticity or lower compliance with prescribed patching. The aim of this study was to determine the dose-response relationship and treatment efficiency from acuity gain and electronically recorded patching dose rates, and to infer from these parameters on a facet of age dependence of functional plasticity related to occlusion for amblyopia. The Occlusion Dose Monitor was used to record occlusion in 27 participants with previously untreated strabismic and/or anisometropic amblyopia aged between 5.4 and 15.8 (mean 9.2) years during 4months of conventional treatment. Group data showed improvement of acuity throughout the age span, but significantly more in patients younger than 7years despite comparable patching dosages. Treatment efficiency declined with age, with the most pronounced effects before the age of 7years. Thus, electronic recording allowed this first quantitative insight into occlusion treatment spanning the age range from within to beyond the conventional age for patching. Though demonstrating improvement in over 7year old patients, it confirmed the importance of early detection and treatment of amblyopia. Treatment efficiency is presented as a tool extending insight into age-dependent functional plasticity of the visual system, and providing a basis for comparisons of effects of patching vs. emerging alternative treatment approaches for amblyopia.

The effect of occlusion therapy on motion perception deficits in amblyopia

“…On average, the children had been prescribed 1600 h (range: 0-8133 h, SD = 1940, Mdn = 823.3) of occlusion therapy, with a mean compliance of 83% based on parental report, prior to the first test session. This is similar to the compliance level of 77% reported with an electronic occlusion dose monitor (Fronius et al, 2014). At each test visit, visual acuity was assessed using the Regan high-contrast letter chart (Regan, 1988).…”

“…1 This often works quite well, particularly in children under the age of 7 years (Fronius et al, 2014), but occlusion fails to restore visual acuity in the amblyopic eye in up to one third of cases (Clarke et al, 2003;Flynn et al, 1999). This is partly because children and their parents do not always follow the treatment instructions they are given, so their compliance is poor (Fronius et al, 2014). However, failures can also occur when 1 Atropine drops or a fogged lens (Bangerter foil) may also be used to penalize the fellow eye, with similar results (Pediatric Eye Disease Investigator Group, 2008Group, , 2010.…”

“…In typical treatment for amblyopia, after the amblyogenic factors such as anisometropia or strabismus are corrected, the clinically unaffected fellow eye is occluded with a patch to improve the visual acuity of the amblyopic eye. 1 This often works quite well, particularly in children under the age of 7 years (Fronius et al, 2014), but occlusion fails to restore visual acuity in the amblyopic eye in up to one third of cases (Clarke et al, 2003;Flynn et al, 1999). This is partly because children and their parents do not always follow the treatment instructions they are given, so their compliance is poor (Fronius et al, 2014).…”

Sensory and cognitive plasticity: implications for academic interventions

“…However, children’s responsiveness to this treatment is highly age-dependent: earlier intervention is more effective . Cross-sectional studies report that children under the age of seven respond best to patching, confirming standard clinical practice [16,17]. Older children can respond to treatment, but the efficacy is substantially worse and thus the condition is less likely to fully resolve.…”

“…Behaviorally, animal models of monocular deprivation closely parallel human experiences with amblyopia, but it is unclear whether animal models of cognitive enrichment and social isolation adequately mirror the diversity of human cognitive experiences. Clinically, treatment efficacy is easily defined and measured in vision, e.g., acuity gain per 100 hours of patching [17], but optimal outcomes are more difficult to define in cognitive plasticity research. Most interventions show effects on some cognitive and academic measures but not others and the relative importance of these measures is unclear.…”