Retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in children with obesity

Obesity-induced ocular changes in children and adolescents: A review

Childhood obesity has reached epidemic levels worldwide. Overweight and obesity is associated with an increase in several inflammatory markers, leading to chronic low-grade inflammation responsible for macro- and microvascular dysfunction. While the impact of obesity on overall health is well-described, less is known about its ocular manifestations. Still, there are few studies in children and adolescents in this regard and they are inconsistent. However, some evidence suggests a significant role of overnutrition in the development of changes in retinal microvasculature parameters (wider venules, narrower arterioles, lower arteriovenous ratio). Higher values of intraocular pressure were found to be positively correlated with high body mass index (BMI) as well as obesity. In addition, the retinal nerve fiber layer (RNFL) values seem to be lower in obese children, and there is a significant negative correlation between RNFL values and anthropometric and/or metabolic parameters. Changes also could be present in macular retinal thickness and choroidal thickness as well as in the retinal vessel density in children with obesity. However, these associations were not consistently documented. The purpose of this review is to present the most current issues on child obesity and the related potential ocular effects through an overview of international publications from the years 1992-2022.

Macular Variability in Children and Adolescents with Metabolic Syndrome: A Cross-sectional Study Examining the Associations with Anthropometric Measurements, Metabolic Parameters and Inflammatory Markers

OBJECTIVE

Macular damage may be observed in obesity and metabolic syndrome (MetS), a condition which leads to chronic subclinical inflammation and affects most organ systems. To investigate the association between macular variability and anthropometric measurements, metabolic parameters, and inflammatory markers in children and adolescents with MetS.

METHODS

Two hundred and twenty eyes of 62 obese and 48 healthy children and adolescents were examined. Bilateral macular retinal thickness (MRT) and macular retinal volume (MRV) were measured in all subjects using optical coherence tomography. Associations between mean MRT and mean MRV and age, auxological measurements including body mass index standard deviation scores (BMI-SDS) and waist circumference-SDS (WC-SDS), metabolic parameters and inflammatory parameters including neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio and systemic immune-inflammatory index (SIII) were investigated.

RESULTS

No statistically significant difference was observed between the groups in terms of age or sex distribution (p>0.05). Mean MRT (r=-0.326, p=0.007) and MRV (r=-0.303, p=0.007) values in the obese group with MetS decreased as homeostasis model assessment-insulin resistance (HOMA-IR) values increased. SIII values were higher in obese groups, but particularly in obese subject with MetS, compared to the control group (p=0.021). The decrease in mean MRT (r=-0.544, p=0.046) and MRV (r=-0.651, p=0.031) in the obese subjects with MetS was negatively correlated with NLR. Mean MRT and MRV decreased in all obese subjects as SIII increased (p<0.05).

CONCLUSION

This is the first study to show that mean MRT and MRV values decrease as BMI-SDS, WC-SDS and HOMA-IR increase in obese children and adolescents with MetS. NLR and SIII may serve as markers of chronic inflammation in obese children with MetS associated with macular damage.

Somatic neural alterations in non-diabetic obesity: a cross-sectional study

BACKGROUND

Reports on alterations in somatic neural functions due to non-diabetic obesity, a major risk factor for diabetes, are few and still a matter of debate. Nevertheless, to our knowledge, reports lack any comments on the type of somatic nerve fibers affected in non-diabetic obesity. Therefore, this study aimed to find out the alteration in somatic neural functions in non-diabetic obese persons if any.

METHODS

The study was conducted on 30 adult non-diabetic obese persons (mean age 32.07 ± 7.25 years) with BMI > 30 Kg/m2 (mean BMI 30.02 ± 2.89 Kg/m2) and 29 age- and sex-matched normal weight controls (mean age 30.48 ± 8.01 years) with BMI: 18-24Kg/m2 (mean BMI 21.87 ± 2.40 Kg/m2). Nerve conduction study (NCS) variables of median, tibial and sural nerves were assessed in each subject using standard protocol. The data were compared by Mann Whitney 'U' test.

RESULTS

In comparison to normal weight persons, obese had lower compound muscle action potential (CMAP) amplitudes of right median [9.09(7.62-10.20) Vs 10.75(8.71-12.2) mV, p = 0.025] and bilateral tibial nerves [Right: 8.5(7.04-11.18) Vs 12.1(10.55-15) mV, p < 0.001 and left 9.08(6.58-11.65) Vs 13.05(10.2-15.6) mV, p = 0.002]. Furthermore, obese persons had prolonged CMAP durations of right and left median [10.5(9.62-12) Vs 10(8.4-10.3) ms, p = 0.02 and 10.85(10-11.88) Vs 10(9-10.57) ms, p = 0.019] and right tibial [10(9-11) 8.5(7.92-10) ms, p = 0.032] nerves. Sensory NCS (sural nerve) also showed diminished sensory nerve action potential (SNAP) amplitude [16(12.08-18.21) vs 22.8(18.3-31.08) μV, p < 0.001] and prolonged duration. However, onset latencies and conduction velocities for all nerves were comparable between the groups.

CONCLUSION

This study documents subclinical peripheral nerve damage in non-diabetic obese with abnormal NCS parameters; shorter amplitudes and prolonged CMAP and SNAP durations. The reduced amplitudes of mixed and sensory nerves might be due to decreased axonal number stimulation or actual decrease in number of axonal fibers, or defect at NMJ in non-diabetic obese. Prolonged durations but normal onset latencies and conduction velocities strongly suggest involvement of slow conducting fibers.