In a recent study published in the American Journal of Ophthalmology, researchers assessed the effect of blue-light filtering (BLF) intraocular lenses (IOLs) on the development and progression of macular atrophy (MA) in eyes with neurovascular age-related macular degeneration (nAMD).
Give me some background first.
Let's talk AMD: AMD is the leading cause of irreversible blindness in older adults aged 65+. The disease causes damage to the macula and can blur the central vision.
Now BLF IOLs: These IOLs filter short-wave light and selectively reduce the transmission of ultraviolet (UV) radiation.
Now, talk about the study.
Researchers conducted a retrospective registry-based cohort study of consecutive cataract surgeries performed between September 2007 and September 2018 at the Ophthalmology Unit of Kymenlaakso Central Hospital in Kotka, Finland.
The inclusion criteria to study a nAMD cohort was the availability of consecutive optical coherence tomography (OCT) follow-ups of every participant in the study.
Note: The investigators noted that follow-ups of each patient were not retrospectively applicable for non-nAMD participants.
Who were the participants?
The study included 373 patients (373 eyes) with concomitant nAMD who received intravitreal anti-vascular endothelial growth factor (VEGF) injections and underwent uneventful cataract surgery.
Among the participants, 206 eyes were implanted with BLF IOLs and 167 eyes were implanted with standard IOLs.
Patient demographics were:
- Aged 50+
- Mean age 78.6±6.7 at surgery
- 67.4% female
How was the study designed?
The investigators conducted the following:
- Compared subsequent MA rates between the BLF IOL and non-BLF IOL participants
- Manually reviewed OCT scans in a masked manner to examine patient baseline variables and IOL status
- Assessed a patient’s overall risk of developing new-onset MA and the effect of the IOL type on disease progression
Technology update: Heidelberg Engineering software was used to manually evaluate and calculate the MA area.
Study duration: Patients were followed until June 2023; death was considered a censoring event.
Findings?
The researchers found that both groups had comparable baseline parameters including:
- Age
- Sex
- Corrected distance visual acuity (VA)
- Macular thickness
- Cumulative number of anti-VEGF injections
- Comparable follow-up times
- 3164±1420 days vs. 3180±1403 days, respectively, P=0.908
How many MA cases were detected?
It was discovered that:
- Nine pre-existing and 77 new-onset MA cases were detected
- Similar distribution between BLF (P=0.598) and non-BLF eyes (P=0.399)
When adjusted for age and sex, the Univariate Kaplan Meier (P=0.366) and multivariate Cox regression analysis showed:
- BLF-IOLs were comparable to non-BLF IOLs in relation to risk for new-onset MA
- (HR 1.236, 95% CI 0.784-1.949, P=0.363)
What about the data for MA?
Final MA area at the last visit was:
- 5.14±4.71mm2 for BLF IOLs (P=0.028)
- 8.56±9.17mm2 for non-BLF IOLs (P=0.028)
The mean annual MA area increase was:
- 78±0.84mm2 (P=0.042)
- 1.26±1.32mm2 (P=0.042)
Limitations?
The authors noted that the study was retrospective in design.
Why this matters: Residual confounding such as smoking, sunlight exposure, and genetic predisposition may have been present and were not accounted for.
Further, allocation to IOL type was at the surgeon’s discretion and not randomized; plus, the authors stated that they did not use fully automated image detection software.
A full overview of the limitations can be found here.
Expert opinion?
The investigators recommended that further research be conducted to observe if these findings can be generalized for a non-wet AMD cohort.
Take home.
The results of this study show that, while there is no added benefit of BLF IOLs to non-BLF IOLs regarding MA-free survival, BLF IOLs were associated with less MA progression over time.
The authors stated this may suggest that, “filtering the shorter wavelengths of light using BLF-IOLs could provide protection against MA progression.”