A study recently published in the American Journal of Ophthalmology assessed whether blue-light filtering (BLF) intraocular lenses (IOLs) reduce the risk of exudative age-related macular degeneration (AMD).
Give me some background.
In vitro and animal studies have demonstrated that blue light contributes to retinal degeneration by damaging the retinal pigment epithelium (RPE) and photoreceptors via:
- Mitochondrial dysfunction
- Cell apoptosis
- Endoplasmic reticulum stress
- Inflammation
Stick with this human-based research …
While human studies are limited, long-term exposure, particularly in the blue light spectrum, has been considered a risk factor for retinal degenerative diseases.
As a result; This has led to the hypothesis that reducing blue light exposure may prevent AMD.
- However: Evidence remains insufficient to confirm that blue light exposure from daily activities causes retinal toxicity in humans.
Consequently: Given these uncertainties, a research team from Korea sought to elucidate whether BLF IOLs effectively reduce AMD incidence in daily environments.
Now talk about the study.
In this nationwide, population-based cohort study, investigators utilized data from the Korean National Health Insurance Sharing Service (NHISS) database.
Inclusion criteria: Individuals who underwent cataract surgery and received the same type of IOL (BLF or clear) in both eyes within one year between January 2012 and December 2018.
And the setup for this analysis?
Participants were organized into one of two groups:
- BLF IOL group
- n = 21,741
- 33.3% male, mean age: 71.4 years
- Clear IOL group
- n = 56,357
- 34.9% male, mean age: 71.3 years
The research team then compared the risk of exudative AMD between the two.
What was measured?
Main outcome measures included (for exudative AMD):
- 10-year cumulative incidence
- Incidence rate
- Hazard ratios (HRs)
Cox proportional hazard models and the Fine-Gray model were applied to calculate adjusted HRs (aHRs), with 95% confidence intervals (CIs), adjusting for age, sex, socioeconomic status, and systemic diseases
- Further: The same analysis was performed in the cohort matched by age, sex, and the calendar year of the index date.
Findings?
The mean follow-up duration was 7.0±2.5 years in the BLF IOL group and 6.7±2.5 years in the clear IOL group (P = 0.069).
The 10-year cumulative incidence of exudative AMD for the BLF IOL group was 1.8% (95% CI: 1.5-2.0%) compared to 1.7% (95% CI: 1.5-1.8%) in the clear IOL group.
Anything else?
The incidence rates per 100,000 person-years were 162.8 and 153.9 in the BLF IOL and clear IOL groups, respectively.
- Additionally: There was no significant difference in the adjusted Cox model (aHR: 1.12, 95% CI: 0.96-1.30, P = 0.149) and the Fine-Gray model (aHR: 1.15, 95% CI: 0.97-1.36, P = 0.120).
Subgroup analyses based on age, sex, and history of nonexudative AMD revealed no protective effect of BLF IOLs, with comparable incidence rates across all subgroups.
- Moreover: Similar results were reported in the matched cohort analysis.
Expert opinion?
When explaining these results, the study authors noted: “Despite substantial evidence from in vitro and animal models linking BLF IOLs and AMD, these lenses may fail to demonstrate effectiveness in clinical human studies because blue light exposure in daily life is not a major contributing factor to AMD.”
- In addition: They speculated that racial characteristics may influence AMD risk
- Why: Because East Asians generally have a higher concentration of melanin pigment in the iris and retinal pigment epithelium (RPE)—potentially causing a protective effect against light-induced retinal damage.
Take home.
These findings demonstrate that BLF IOL implantation in cataract surgery does not reduce the risk of developing exudative AMD in the South Korean population, regardless of a history of nonexudative AMD.
For the future: Further research is warranted to explore multiethnic populations, longer follow-up periods, and other potential benefits of BLF IOL use.