Medicontur 1stQ AddOn®: The “Swiss Army Knife” Lens – With Toric Stability

The AddOn® supplementary IOL family has earned the nickname “Swiss army knife” of lenses because it lets surgeons fine‑tune vision in pseudophakic eyes without disturbing a stable capsular bag IOL. For surgeons, the toric AddOn® is especially relevant: it delivers reliable astigmatism correction in the ciliary sulcus with strong evidence of safety and stability.

Why A Sulcus Add-On?

Many patients still have visual limitations after otherwise successful cataract surgery:

• Residual spherical or astigmatic error
• Complex corneas (post‑keratoplasty, post‑PPV, post‑refractive surgery)
• Monofocal IOLs in patients who now want spectacle independence

Corneal laser isn’t always ideal in these cases. A purpose‑designed sulcus IOL allows refractive fine‑tuning and even presbyopia correction while leaving the primary in‑the‑bag lens untouched – and remains reversible if circumstances change.

Designed For The Sulcus – Not Adapted To It

Earlier piggyback approaches often used standard bag‑designed IOLs in the sulcus, leading to iris chafing, pigment dispersion, angle closure and interlenticular opacification. The 1stQ AddOn® platform was engineered specifically to avoid these issues:

• Convex–concave optic creates ~500–600 μm clearance from the primary IOL, minimising IOL touch and interlenticular opacification.
• Square 6.0 mm optic with rounded edges helps prevent iris capture and pigment dispersion.
• Four closed-loop “4‑flex” haptics (13.0 mm overall) give four‑point fixation and excellent centration across a wide range of sulcus sizes.
• Hydrophilic acrylic (25% water) with UV absorber offers proven uveal biocompatibility.

These design features are common to the monofocal, toric, trifocal and trifocal toric AddOn® models.

Safety In The Sulcus

Across multiple clinical series, AddOn® lenses have shown:

• Stable IOP – no significant change compared with pre‑op, with pressures remaining in the physiological range.
• Minimal endothelial cell loss – typically around 2%, much lower than during primary phacoemulsification.
• Preserved anterior segment anatomy – OCT and gonioscopy show deep chambers and open angles after implantation.
• Very low complication rates – no reported patterns of dislocation, iris capture, clinically significant pigment dispersion or angle‑closure glaucoma when eyes are appropriately selected.

This profile is particularly important when operating on eyes that already have a premium or otherwise well‑functioning bag IOL.

Toric AddOn®: Proven Rotational Stability

For toric lenses, stability is critical; rotation quickly erodes astigmatic correction. The toric AddOn® has now been independently studied in several cohorts:

• In a long‑term series of 18 eyes, the mean absolute change in axis from surgery to final follow‑up was only 4.9° ± 3.7°, with no lenses requiring repositioning.
• In a head‑to‑head comparison with another widely used C‑loop toric sulcus IOL, the C‑loop design needed repositioning in around 62% of eyes. In contrast, no toric AddOn® lenses in that comparison required further surgery, and mean rotation remained low.
• A 22‑eye series using the monofocal toric AddOn® for residual astigmatism found:
  • 82% of eyes with residual cylinder ≤0.50 D, 100% ≤1.00 D
  • Mean absolute rotation of 3.2° ± 3.3° at 3 months
  • Only two eyes (9.1%) required a single early repositioning, with stable alignment thereafter.

These data comfortably meet typical rotational stability benchmarks and compare favourably with older sulcus toric platforms.