In this study, the authors used data from the UK Biobank to examine the association of caffeine intake with intraocular pressure (IOP) and glaucoma, and whether genetic predisposition to higher IOP modified these associations. The authors reported that coffee, tea and caffeine consumption were associated weakly with lower IOP, and the association between these exposures and glaucoma were null. However, once exposed to correction for an IOP Polygenic Risk Score, the data support a positive association between caffeine intake and both IOP and glaucoma prevalence, but only among those with the highest genetic susceptibility to elevated IOP.
Once exposed to correction for an IOP Polygenic Risk Score, the data support a positive association between caffeine intake and both IOP and glaucoma prevalence, but only among those with the highest genetic susceptibility to elevated IOP
The strengths of study include (a) a very large sample size of 121,374 participants; and (b) an objective accurate estimate of the IOP (the authors adopted the Ocular Response Analyzer technology, thereby offsetting the measurements for cornea-induced confounders). Weaknesses include a rather weak definition of glaucoma (based upon either patient's reported 'doctor's opinion' or ICD-labelling in medical records) that is exposed to the risk of overestimation (e.g., an ocular hypertensive patient might have being mistaken for an actual glaucoma patient). As well, no data on the severity of the disease are available. However, the appropriate and aided by the large sample size, the outcomes are well-defined and the results are well-supported by the data analysis.
The study's results are consistent with the concepts of personalized medicine. While confirming the available literature on the inconclusive results of generalized analyses on the relationship between caffeine consumption and elevated IOP/glaucoma, they offer a potential path for a better understanding by correcting the data for genetic susceptibility. This study is strategic in promoting a less generalized epidemiology, and thereby offering the clinician more precise tools to understanding the risk to individual patients encountered in everyday practice.
Last, but not least, the data on caffeine consumption have been collected from a large sample of individuals living in the UK. Since the British habits, in terms of caffeine consumption, might not be comparable to what has been observed in other parts of the world. Albeit showing valid results , extending them to the general world population needs further studies.