What is IOL stability?
Stability refers to the positional, rotational, optical, and material integrity over time. Key facets include resistance to dislocation, rotation (especially for toric lenses), decentration/tilt, material degradation, and maintaining optical power.
Why it matters
Visual outcomes depend heavily on stability, especially with premium IOLs (e.g. toric, multifocal). Misalignment or rotation can degrade vision quality.
Long-term complications can cause patient morbidity (e.g. glare, poor focus, need for secondary surgery).
Material biocompatibility and durability are essential for implants that will stay in the eye for decades.
These are both design and biological/environmental.
Haptic material, shape, flexibility and configuration influence how well the IOL is secured in the capsular bag or sulcus; sharp edges, loop/haptic design affect rotational stability. Studies show different designs vary in rotational drift.
How well the IOL is centered, how sutures are placed (if needed), how securely it is settled in the capsule. Poor fixation or leaving potential movement leads to late dislocation. A study of repositioning IOLs (1-piece vs 3-piece etc.) showed that with good technique, long-term safety can be comparable.
The lens capsule tends to contract, proliferating lens epithelial cells (LECs) can cause posterior capsule opacification (PCO), which can exert forces on the IOL. Also risk factors like pseudoexfoliation, inflammation.
Material affects biocompatibility, clarity, resistance to opacification or yellowing. For example, “yellow” vs “clear” IOL biostability has been compared in vitro.
For toric IOLs, rotational stability is especially critical. Evidence suggests some IOLs hold rotation better than others, and that design choices impact tilt and decentration.
Exposure to UV, oxidative stress; long-term effects of tinted materials; risk of calcification or other opacities over time.
A study comparing three different toric IOL models looked at their rotational stability over time; important especially right after surgery when rotation tends to happen.
A cohort study looked at patients with “late in-the-bag” dislocation and compared 1-piece vs 3-piece designs repositioned by scleral suturing. Outcomes over 2+ years showed similar safety and visual acuity between designs.
An in vitro study simulated intraocular environment to assess how different IOL materials (yellow filter tinted vs clear) maintain clarity, structural integrity etc. over long durations.
Another recent paper evaluated a new IOL, measuring how stable its position and orientation remains (tilt, decentration) in vivo over time.
To assess whether an IOL is stable in the long term, the following metrics or endpoints are useful:
Choosing the right intraocular lens is only part of the journey—ensuring its long-term stability is what secures vision for years to come. At InVision Biomedical, we combine precision design, advanced materials, and rigorous testing to deliver lenses that stand the test of time.
