Millions of patients who underwent radial keratotomy (RK) in the 1980s and '90s are now hitting cataract surgery age — and they're bringing a uniquely complicated set of challenges. RK incisions, which can reach 90% of corneal depth, permanently weaken the cornea's structure, causing it to flatten overnight and steepen throughout the day. This "diurnal shift" can swing vision by 0.5 D to over 1.5 D within a single day, making standard IOL selection a real challenge.

The emerging consensus among experts is that nondiffractive EDOF IOLs are the go-to choice for most post-RK cataract patients, offering roughly 1.75 D of continuous visual range that acts as a buffer against daily corneal fluctuations. For highly aberrated corneas, the small-aperture IC-8 Apthera IOL (which uses a pinhole effect to mask up to 2–3 D of irregular astigmatism) and the Light Adjustable Lens (LAL), which can be fine-tuned post-surgery, are strong alternatives. Traditional diffractive multifocal IOLs are generally avoided due to contrast sensitivity loss.

Key Takeaways:

• Target a slight myopic refraction of –0.25 D to –0.75 D to buffer against the ongoing hyperopic shift in post-RK eyes
• Use dedicated post-refractive biometry formulas (e.g., Barrett True-K, ASCRS/ESCRS calculators) — standard formulas tend to err toward hyperopia
• Screen corneal higher-order aberrations: if below 0.45 µm, EDOF or enhanced monofocal IOLs may be suitable; higher aberrations favor the IC-8 or LAL
• Consider a scleral tunnel incision to avoid intersecting old RK cuts, and always perform a fluorescein dye leakage test at closure

Why it matters: As the RK generation ages into cataract territory, surgeons need a clear playbook. The right IOL choice — paired with meticulous planning and honest patient counseling — can transform a complex, unpredictable case into a rewarding outcome.