Findings from a recent study published in eClinicalMedicine evaluated whether children with amblyopia have an increased risk of cardiometabolic disorders as adults.
Give me some background first.
Primary amblyopia is a neurodevelopmental condition affecting 1-3% of children globally and is the most common cause of pediatric vision loss.
There is a known association between neurodevelopmental impairment and cardiometabolic dysfunction later in life, which prompted a British research team to investigate the association between amblyopia and cardiometabolic diseases.
Now talk about the study.
In this cross-sectional and longitudinal study, researchers analyzed the data of 126,399 United Kingdom (UK) Biobank participants aged 40+ who underwent ophthalmic examinations.
Within this cohort, a subset of 67,321 participants received color fundus photography (CFP).
Of note, the UK Biobank is a large-scale biomedical database and research resource with de-identified genetic, lifestyle, and health information and biological samples from 500,000 UK participants.
Keep going…
Participants with childhood amblyopia were sorted into either “resolved” or “persisting” amblyopia by adulthood. Cardiometabolic disease and mortality were defined using:
- Ophthalmic assessment
- Self-reported questionnaires
- Hospital admissions
- Death records
Additionally, morphological features of the optic nerve and retinal vasculature and sublayers were extracted from CFP and optical coherence tomography (OCT) imaging.
Findings?
Compared to non-amblyopic participants (18,481), individuals with persisting amblyopia (2,647) were more likely to be:
- Obese (adjusted odds ratio [AOR] 1.16 [95% confidence interval (CI) 1.05-1.28])
- Hypertensive (AOR 1.25 [95% CI 1.13-1.38])
- Diabetic (AOR 1.29 [95% CI 1.04-1.59])
The authors also found that amblyopia was associated with an increased risk of myocardial infarction (adjusted hazard ratio [AHR] 1.38 [95% CI 1.11-1.72]) and death (AHR 1.36 [95% CI 1.15-1.60]).
Did childhood amblyopia impact retinal morphology in adulthood?
On retinal imaging, amblyopic eyes had:
- Significantly increased venular caliber (0.29 units [95% CI 0.21-0.36])
- Increased tortuosity (0.11 units [95% CI 0.03-0.19])
- Lower fractal dimension (-0.23 units [95% CI -0.30 to -0.16])
- Thinner macular ganglion cell-inner plexiform layer (mGCIPL, -2.86 microns [95% CI -3.47 to -2.22])
Further, non-amblyopic fellow eyes also had significantly lower retinal fractal dimension (-0.08 units [95% CI -0.15 to -0.01]) and thinner mGCIPL (-1.14 microns [95% CI -1.74 to -0.54]).
Amblyopic eyes with a persisting visual deficit had smaller optic nerve disc height (-0.17 units [95% CI -0.25 to -0.08]) and width (-0.13 units [95% CI -0.21 to -0.04]).
Anything else?
The study authors noted that differences in retinal features in both the amblyopic and unaffected non-amblyopic eye in patients with persisting amblyopia indicate a generalized versus localized systemic structural dysregulation of brain and visual pathways in amblyopia.
However …
These changes in retinal features were not observed in adults with amblyopia that resolved following treatment, indicating that early life neurodevelopmental dysregulation is associated with cardiometabolic conditions in later life.
Limitations?
While the sample of participants with amblyopia was large, it was mainly comprised of individuals with persisting amblyopia.
Additionally, the primary analysis utilized self-reported medical conditions, which are potentially subject to recall bias.
Ultimately, the authors highlighted that the current study design and analysis “cannot interrogate any causal relationship between amblyopia and cardiometabolic outcomes.”
Take home.
These findings suggest that adults who had amblyopia in childhood have an increased risk of cardiovascular disease and metabolic dysfunction.
As such, the study authors concluded that eyecare practitioners can be cognizant and proactive in the monitoring of cardiometabolic dysfunction in adults who had childhood amblyopia.
Next steps?
Further research is required to validate these findings and elucidate the basis of this observed association.
The authors recommended that optic nerve morphology be investigated as a prognostic factor for treatment response in children undergoing amblyopia treatment.