Temporal summation in children with a history of retinopathy of prematurity
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Published on: April 2, 2021
Ronald M Hansen1, Anne Moskowitz1, Jena L Tavormina1
1Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
Insights
Children with retinopathy of prematurity (ROP) show prolonged temporal summation, indicating delayed visual processing. This study measured the critical duration (tCRIT) in ROP patients, finding significantly longer times for complete summation.
Area of Science:
- Ophthalmology
- Neuroscience
- Visual Science
Background:
- Retinopathy of prematurity (ROP) is a condition affecting premature infants that can lead to visual impairment.
- Previous electroretinography (ERG) studies suggest prolonged phototransduction kinetics in the rod photoreceptors of individuals with ROP.
- Temporal summation, the ability of the visual system to integrate stimuli over time, is a key aspect of visual processing.
Purpose of the Study:
- To evaluate temporal summation in children with a history of ROP by measuring the critical duration (tCRIT) for complete summation.
- To investigate whether ROP affects the time course of rod-mediated visual responses.
Main Methods:
- A psychophysical method using a two-alternative, spatial, forced-choice procedure was employed.
- Dark-adapted visual thresholds were determined for stimuli of varying durations (10–640 ms).
- The critical duration (tCRIT) was estimated in groups of children with severe ROP, mild ROP, no ROP history, and term-born controls.
Main Results:
- The critical duration (tCRIT) for complete temporal summation was significantly longer in children with a history of ROP compared to controls.
- No significant difference in mean tCRIT was found between the mild and severe ROP groups.
- Both ROP groups exhibited significantly longer tCRIT values than those without ROP history and term-born controls.
Conclusions:
- Children with a history of ROP demonstrate a significantly prolonged critical duration (tCRIT).
- This prolongation suggests abnormal kinetics within the rod outer segment of the retina in ROP subjects.
- The findings indicate a lasting impact of ROP on the temporal processing capabilities of the rod visual system.
Purpose:
To assess temporal summation in children with a history of retinopathy of prematurity (ROP) by determining the critical duration (tCRIT) for complete temporal summation under rod-mediated conditions. From prior ERG studies, it is known that the kinetics of activation of phototransduction are prolonged in the ROP rod photoreceptor.
Methods:
Dark-adapted thresholds for detecting 10° diameter stimuli with durations from 10 to 640 ms were measured. A two-alternative, spatial, forced-choice psychophysical procedure was used. The tCRIT for complete summation was estimated in former preterm subjects with a history of severe ROP (n = 7), mild ROP (n = 23), and no ROP (n = 15). The subjects ranged in age from 10.4 to 17.6 (median 15.6) years. Age-similar term-born control subjects (n = 5) were also tested.
Results:
Critical duration was significantly longer in subjects with a history of ROP than in subjects who never had ROP or who were born at term. Mean tCRIT in the mild ROP group [127.5 (SD = 19.9) ms] and severe group [147.6 (SD = 18.9) ms] did not differ significantly, but both were significantly longer than in former preterms who never had ROP [101.1 (SD = 16.5) ms] and in term-born controls [101.0 (SD = 19.5) ms].
Conclusions:
In ROP subjects, tCRIT is significantly prolonged. This is likely due to abnormal kinetics in the rod outer segment.
