The Light Adjustable Lens (LAL) is an intraocular lens that can be non-invasively adjusted after cataract surgery by exposure to ultraviolet (UV) light to change its power.
Achieving accurate postoperative refraction remains a challenge in cataract surgery. Inaccurate biometry, errors in predicting effective lens position, and individual variations in wound healing are major causes of postoperative refractive error. The Light Adjustable Lens was developed to address these issues.
This technology was pioneered in 1997 by Dr. Schwartz at the University of California, San Francisco, and Professor Grubbs at the California Institute of Technology, and received FDA approval on November 22, 2017.
In an FDA clinical trial (600 cases), the LAL group achieved 20/20 uncorrected visual acuity at twice the rate of the standard monofocal IOL group 1). High refractive accuracy was reported, with 92% of patients within 0.5 D of target refraction after adjustment.
The Light Adjustable Lens is intended for patients with postoperative refractive error (residual hyperopia, myopia, or astigmatism).
The postoperative course and adjustment process after light-adjustable lens implantation are described below.
Implantation to Pre-Adjustment
Healing period: Refractive stability is confirmed 2 to 4 weeks after implantation.
Refraction test: Manifest refraction is performed to evaluate the difference from the target refraction.
Pupil dilation confirmation: Pupil dilation of at least 6.5 to 7 mm is required for light adjustment.
UV Irradiation to Lock-In
Number of irradiations: Adjustment is performed over 2 to 4 sessions (each 40 to 120 seconds, approximately 3 days apart).
Lock-in: After achieving the target refraction, the entire optic is irradiated with UV light to lock the power.
UV-blocking glasses: Must be worn for up to 24 hours after lock-in.
Changes in the shape of the light-adjustable lens can be confirmed with anterior segment optical coherence tomography. Spherical power adjustment changes the curvature radius of the anterior and posterior surfaces, while astigmatism correction produces asymmetric shape changes2).
The FDA approval criteria are as follows.
Light-adjustable intraocular lenses are not recommended for the following patients.
In addition to standard preoperative cataract evaluation, confirm the following:
| Evaluation Item | Details |
|---|---|
| Refraction Test | Manifest refraction, uncorrected distance visual acuity, best corrected visual acuity |
| Optical Coherence Tomography | Exclusion of macular edema (recommended before and after UV irradiation)1) |
| Pupil dilation evaluation | Confirm at least 6.5–7 mm dilation |
If visual acuity decreases after UV irradiation, perform macular evaluation using optical coherence tomography. Cases of cystoid macular edema after UV irradiation have been reported, and early detection is important1).
If visual acuity decreases after UV irradiation, cystoid macular edema is a possibility. Discontinue UV irradiation and evaluate the macula with optical coherence tomography. For cystoid macular edema, treatment with topical nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroid eye drops has been reported to be effective1).
The light-adjustable intraocular lens contains photosensitive molecules called “macromers” within a silicone matrix. Irradiation with 365 nm UV light causes the macromers to polymerize, creating a concentration gradient between irradiated and non-irradiated areas. Over the following 12 hours, unreacted macromers diffuse, changing the lens curvature and thus the refractive power3).
After adjustment is complete, a lock-in treatment (UV irradiation of the entire optic) polymerizes all remaining macromers, fixing the power.
The adjustment device (Light Delivery Device) consists of a slit-lamp microscope with an optical projection system and UV light source, focusing on the intraocular lens through a contact lens placed on the cornea. Pupil dilation of at least 7 mm is required, and all light adjustments are performed under dilation.
The mechanism by which unpolymerized photosensitive silicone macromers migrate along a concentration gradient after UV irradiation is fundamental to the power adjustment of light-adjustable intraocular lenses3).
In spherical power adjustment, both anterior and posterior surface radii of curvature change. A Japanese research group visualized the actual lens shape changes using an anterior segment optical coherence tomography device (CASIA2)2).
Kato et al. (2025) reported that in a 70-year-old male, after spherical power adjustment (+0.75 D → −0.25 D), the anterior radius of curvature decreased from 11.59 mm to 9.03 mm, and the posterior radius increased from 10.98 mm to 13.41 mm2). In an astigmatism correction case (80-year-old female, Cyl −1.50 D → S +0.25 D), the change in posterior radius of curvature occurred asymmetrically along the astigmatic axis, correcting astigmatism through a mechanism similar to that of toric intraocular lenses.
The following mechanisms are considered for cystoid macular edema caused by UV irradiation1):
Bilateral cystoid macular edema after ultraviolet irradiation is a new complication that has rarely been reported previously.
Shakarchi et al. (2025) reported the world’s first case of simultaneous bilateral cystoid macular edema in an 81-year-old woman who underwent ultraviolet lock-in treatment after implantation of a light-adjustable intraocular lens 1). One week after ultraviolet irradiation, visual acuity decreased to 20/40, and optical coherence tomography revealed cystoid changes with foveal retinal thickness of 397 μm (right eye) and 427 μm (left eye). After discontinuing ultraviolet irradiation and initiating topical prednisolone 1% (4 times/day) and ketorolac 0.5% (4 times/day), the edema completely resolved within three weeks.
The authors recommend “discontinuing ultraviolet irradiation and initiating local treatment at a low threshold” and “considering routine optical coherence tomography before and after adjustment even in low-risk patients” 1).
Refractive Index Shaping, which uses femtosecond lasers to alter the chemical composition of acrylic intraocular lenses, is also under investigation. This technology may allow changes in spherical, cylindrical, and power across a single lens, and is expected to enable multiple adjustments through a mechanism different from light-adjustable intraocular lenses 3). Multi-component intraocular lenses, mechanically adjustable intraocular lenses, magnetically adjustable intraocular lenses, and liquid crystal intraocular lenses are also being studied.
Corneal astigmatism changes over time, which may affect the long-term stability of vision provided by light-adjustable intraocular lenses. The concept of combining adaptive optics with light-adjustable intraocular lenses, where the device automatically detects and corrects optical distortions, has also been proposed.
