Sequential Intrastromal Corneal Ring Segments And Phakic Lens Implantation In Stable Keratoconus – Five-Year Follow-Up Outcomes

Keratoconus is a progressive corneal ectasia marked by thinning and conical protrusion, leading to irregular astigmatism and myopia with reduced visual quality. Corneal collagen cross-linking (CXL) and intrastromal corneal ring segments (ICRS) help stabilize and regularize the cornea. ICRS reduce higher-order aberrations and improve corrected distance visual acuity (CDVA), though residual refractive errors often persist. Phakic intraocular lenses (pIOLs) can correct moderate to high residual ametropia and enhance uncorrected distance visual acuity (UDVA). This study assesses long-term visual and refractive outcomes of sequential ICRS and pIOL implantation in stable keratoconus.

This retrospective study was conducted at a tertiary referral hospital in Braga, Portugal.

This study included patients with Grade I–III stable keratoconus, keratometry 40.0–62.0D, astigmatism <10.0D, axial myopia, and minimum corneal thickness of 400µm at the implantation site. All underwent manual ICRS followed by pIOL implantation with 3.2mm anti-astigmatic incisions on the steepest meridian (one for ≤1.0D, two for ≥1.0D). UDVA, CDVA, subjective refraction, and anterior segment optical coherence tomography were assessed preoperatively, at 6 months after each procedure, and at 5 years postoperatively.

Fifty eyes from 42 patients (mean age 36.1±8.5 years) were included. Forty-four Ferrara rings (89.8%) and 5 Intacs (10.2%) were implanted; 37 eyes (74%) received posterior chamber and 13 (26%) iris-fixated IOLs. UDVA improved from 1.00 (IQR 0.30) to 0.70 (IQR 0.30) after ICRS (p=0.002) and 0.22 (IQR 0.26) after pIOL (p<0.001). CDVA improved from 0.52 (IQR 0.51) to 0.22 (IQR 0.22) and 0.15 (IQR 0.20) (all p<0.001). Visual outcomes remained stable at 5 years (p>0.05). Efficacy and safety indexes were 1.33 and 1.52. Spherical equivalent improved from –10.62D to 0.37D (p<0.001). Cylinder decreased from –3.50D to –1.00D (p<0.001). Mean vault at 5 years was 575.7±315.4 μm, trending higher. No angle-closure glaucoma or IOP rise occurred.

Sequential ICRS and pIOL implantation represents a safe and effective therapeutic strategy for visual rehabilitation in keratoconus. ICRS regularizes the corneal surface and reduces irregular astigmatism, creating a more favorable optical profile, while pIOL implantation corrects residual spherical and astigmatic refractive errors, further refined by anti-astigmatic incisions when needed. With careful patient selection, adequate corneal stability, and appropriate surgical timing, this staged approach provides predictable, stable, and sustained long-term visual and refractive outcomes, with a favorable safety profile.