Impact of stimulant treatment on refractive errors and pupil diameter in attention deficit hyperactivity disorder

PURPOSE

The relationship between attention deficit hyperactivity disorder (ADHD) and visual impairment remains poorly understood, and the impact of visual impairment on the development of ADHD is uncertain. The aim of this study was to investigate the refractive profile and ocular biometric characteristics in patients diagnosed with ADHD and compare them with a control group. Additionally, we aimed to explore the potential influence of sex and medication intake.

METHODS

A cohort of 100 participants, including 50 individuals with ADHD and 50 age- and sex-matched control subjects, was included in this study. Ocular biometric parameters were measured, and refractive error was assessed using cycloplegic and non-cycloplegic autorefraction. Subgroup analyses were performed within the ADHD group based on sex, medication intake and age to investigate potential associations with the ocular findings.

RESULTS

We observed no statistically significant differences in axial length, corneal topography parameters or anterior chamber characteristics between ADHD and control subjects. However, subgroup analysis within the ADHD group revealed that the prevalence of ametropia under cycloplegia was significantly higher in unmedicated (69.6%) compared to medicated (37.5%) (X2(2) = 7.320, p = 0.026) participants. Pupil diameter was significantly larger in medicated (3.91 mm) compared to unmedicated (3.58 mm; p = 0.017) individuals. Males had flatter (p = 0.004) and thicker (p = 0.008) corneas than females. Older ADHD participants had higher refractive error (p = 0.008 for non-cycloplegic and p = 0.0.003 for cycloplegic), axial length (p = 0.002) and corneal astigmatism (p = 0.049).

CONCLUSIONS

Our study provides compelling evidence that individuals diagnosed with ADHD exhibit a similar incidence of refractive errors and ocular parameters compared to normal subjects. Nonetheless, the prevalence of refractive errors appears to be higher in unmedicated ADHD patients, suggesting the potential benefit of stimulant treatment. Additionally, stimulant use is associated with an increase in pupil diameter.

Central autonomic regulation assessed by pupillary light reflex is impaired in children with attention deficit hyperactivity disorder

It is assumed that the Attention Deficit Hyperactivity Disorder is associated with the central autonomic dysregulation, however, the studies are rare. Analysis of pupillary light reflex represents a non-invasive tool to provide information related to the central autonomic regulation; thus, we aimed to evaluate potential disturbances in the central autonomic integrity using pupillary light reflex examination in Attention Deficit Hyperactivity Disorder. We have examined 20 children with Attention Deficit Hyperactivity Disorder (10 boys, 13.0+/-2.3 years) and 20 age/gender-matched healthy subjects. Pupillary light reflex was examined at rest for both eyes using Pupillometer PLR-2000 (NeurOptics, USA). Evaluated parameters were: diameter of the pupil before the application of light stimulus and after illumination at the peak of the constriction, the percentual change of the pupil diameter during constriction, average constriction velocity, maximum constriction velocity and average dilation velocity. We found significantly lower percentual change of the pupil diameter during constriction for both eyes in Attention Deficit Hyperactivity Disorder group compared to controls (right eye: -25.81+/-1.23 % vs. -30.32+/-1.31 %, p<0.05, left eye: -25.44+/-1.65 % vs. -30.35+/-0.98 %, p<0.05). The average constriction velocity and maximum constriction velocity were significantly shortened in left eye in Attention Deficit Hyperactivity Disorder group compared to controls (p<0.05). Our findings revealed altered pupillary light reflex indicating abnormal centrally-mediated autonomic regulation characterized by parasympathetic underactivity associated with relative sympathetic predominance in children suffering from Attention Deficit Hyperactivity Disorder.

Pupillometry measurement and its relationship to retinal structural changes in children with attention deficit hyperactivity disorder

PURPOSE

This study aims to assess the pupillometry measurements of the attention deficit hyperactivity disorder (ADHD) patients and to investigate their correlations with macular and RNFL thickness parameters by comparing the values with a healthy control group.

METHODS

Newly diagnosed ADHD patients in a child and adolescent clinic of a tertiary hospital were consulted in an ophthalmology clinic. All participants had undergone a standard ophthalmological examination including refractometry, best corrected visual acuity, color vision, anterior segment biomicroscopy, fundoscopy, pupillometry, and OCT. All results were compared with a healthy control group at the same age.

RESULTS

The study group consisted of 32 patients and there were 43 children in the control group. Mean pupillary velocities of ADHD patients and control group were 0.60 ± 0.11 mm/s and 0.63 ± 0.11 mm/s, and 0.49 ± 0.12 mm/s and 0.50 ± 0.10 mm/s, for right and left eyes, respectively. The difference was statistically significant for both eyes (p < 0.05). Mean RNFL thickness measurements of the study group were 90.69 ± 8.58 μm and 89.63 ± 8.14 μm for right and left eyes, respectively and those were 87.35 ± 7.67 μm and 88.77 ± 7.44 μm, respectively in the healthy group. Correlation between right pupillary velocity and RNFL thickness was statistically significant (r = 0.339, p = 0.003).

CONCLUSION

Higher pupillary velocity values were observed in both eyes of children with ADHD and that was positively correlated with RNFL measurements of their right eyes.

Novel approach to evaluate central autonomic regulation in attention deficit/hyperactivity disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD) is one of the most commonly diagnosed developmental disorders in childhood characterized by hyperactivity, impulsivity and inattention. ADHD manifests in the child's development by deficits in cognitive, executive and perceptor-motor functions, emotional regulation and social adaptation. Although the exact cause has not yet been known, the crucial role in the development of this disease plays the interaction of genetic, neurobiological and epigenetic factors. According to current knowledge, ADHD is defined as a biological dysfunction of central nervous system with genetically or organically defined deficits in noradrenergic and dopaminergic neurotransmission associated with structural abnormalities, especially in prefronto-striatal regions. In this context, a significant part of the difficulties could be due to a faulty control of fronto-striato-thalamo-cortical circuits important for attention, arousal and executive functions. Moreover, ADHD is associated with abnormal autonomic regulation. Specifically, reduced cardiac-linked parasympathetic activity associated with relative sympathetic dominance indexed by low heart rate variability can represent a noninvasive marker for prefrontal hypoactivity. However, the mechanisms underlying altered autonomic regulation in ADHD are still unknown. In this aspect, the evaluation of central autonomic regulation by noninvasive methods, namely pupillometry and eye-tracking, may provide novel information for better understanding of the neurobiological pathomechanisms leading to ADHD.

Pupillary Light Reflex in Children with ADHD

Attention deficit/hyperactivity disorder (ADHD) is one of the most frequently seen mental disorders in children with an increasing risk for other mental disorders. ADHD represents a primary biological dysfunction of the central nervous system, such as dysregulation of frontal-subcortical-cerebellar catecholaminergic circuits and imbalances in the dopaminergic system. However, autonomic nervous system, comprised of two primary branches - sympathetic and parasympathetic nervous systems that are normally in dynamic balance, plays an essential role in the regulation of body functions. Although it is generally assumed that the autonomic regulation is impaired during ADHD the information related to this dysregulation is limited. One of the options to observe changes of autonomic balance in ADHD is pupillary light reflex (PLR). Pupillometric evaluation can be used for the assessment of functioning of both autonomic nervous system branches and certain parameters of pupil responsivity can be helpful as a tool for medical diagnostic and treatment. In conclusion, these findings suggest the pupillometry as a non-invasive method that can indicate abnormalities in the complex central autonomic network regulating PLR.