New research showcased during the 2024 annual Association for Research in Vision and Ophthalmology (ARVO) meeting earlier this month explored the potential impact of relevant climate-related variables on keratoconus prevalence.
Give me some background first.
Keratoconus is a corneal disorder in which the cornea thins and steepens and can lead to blurry or distorted vision.
In its early stage, symptoms can include:
- Mild blurry/distorted vision
- Increased sensitivity to light and glare
- Eye redness or swelling
Now, talk about the study.
Investigators systematically reviewed studies regarding keratoconus prevalence and incidence in the general population.
They utilized climate datasets including the ERA5 and its (unmentioned) derivatives to find climate data for each region analyzed. The EAR5 provides hourly estimates of a large number of atmospheric, land, and oceanic climate variables.
And how was it conducted?
The investigators then:
- Applied population density weighting to enhance exposure accuracy
- Utilized 10 years preceding data collection of each prevalence study as the climate exposure period
- Calculated the averages of relative humidity, wind speed, ultraviolet (UV) radiation, and maximum daily temperature over the 10-year period
- Used simple and multiple linear regression to investigate the potential impact of climate variables on keratoconus
Climate variables that approached significance on simple regression (P≤ 0.1) were included in the multiple regression model.
Note: Estimates from screening studies were excluded from quantitative analysis to ensure interstudy comparability.
How many studies were included in the analysis?
The researchers identified 18 relevant studies that reported keratoconus prevalence across various geographical locations.
Findings?
They determined the following::
- Eight studies with data from 58 states were deemed to have comparable prevalence estimates
- Simple linear regression resulted in the exclusion of maximum daily temperature
- (P=0.158)
- Remaining climate variables included in the multiple regression model showed a negative association between humidity and keratoconus prevalence
- (P= 0.015)
- Maximum daily temperature, wind speed, and UV radiation were not significantly associated with keratoconus prevalence
Expert opinion?
In a study abstract, the researchers stated that, “Future research is needed to confirm the role of low humidity in the pathogenesis of keratoconus, and to assess the potential therapeutic and preventive benefits of humidification.”
Take home.
Low humidity was shown to be an unexplored environmental risk factor for keratoconus while other climate variables did not seem to pose a significant risk.