Patients with cataract and pre-existing corneal irregularities often represent one of the most difficult groups to manage surgically. Irregular astigmatism, higher-order aberrations, and less predictable biometry can all contribute to disappointing visual outcomes and refractive surprises after cataract surgery. A new study from Australia suggests that a small-aperture intraocular lens (IOL) may help address some of these longstanding challenges.
In a retrospective review published in Clinical Ophthalmology, researchers based at Westmead Institute of Medical Research in Sydney evaluated outcomes in 67 eyes of 45 patients with cataract and significant corneal comorbidities who underwent implantation of the IC-8 pinhole IOL (Apthera; Bausch + Lomb). The cohort included patients with keratoconus, previous corneal transplantation, radial keratotomy, corneal scarring, herpetic keratopathy, and other causes of irregular astigmatism.
The IC-8 lens uses pinhole optics, incorporating a 1.36 mm central aperture surrounded by an opaque mask. By restricting peripheral light rays and allowing predominantly paraxial rays to reach the retina, the design aims to reduce the impact of optical aberrations and improve retinal image quality.
Among the 67 eyes studied, 56 received the IC-8 lens alone, while 11 required a secondary piggyback IOL procedure to address significant residual refractive error. Twenty-two patients ultimately underwent bilateral IC-8 implantation.
Visual outcomes were encouraging – in eyes receiving the IC-8 lens alone, mean corrected distance visual acuity improved from 0.56 logMAR preoperatively to 0.16 logMAR after surgery. Uncorrected distance visual acuity averaged 0.24 logMAR, with 61.1 percent of eyes achieving 6/9 vision or better and 75.9 percent reaching driving-standard vision of 6/12 or better.
Refractive outcomes were similarly promising. Mean postoperative spherical equivalent refraction was −0.17 D, with more than half of eyes falling within 0.50 D of target and over 80 percent within 1.00 D.
The strongest results were seen in patients with post-surgical corneal irregularity and keratoconus. Among keratoconic eyes, nearly 70 percent achieved uncorrected visual acuity of 6/9 or better, while more than 86 percent reached 6/12 or better. Outcomes were somewhat less favorable in eyes with corneal scarring or herpetic disease, likely reflecting the highly asymmetric nature of these corneal abnormalities.
The study also compared the performance of five contemporary IOL power calculation formulas – including Barrett Universal II, Kane, EVO, Hill-RBF and Pearl DGS – using measurements from both the IOLMaster 700 and Pentacam. No statistically significant differences were found in refractive prediction accuracy between formulas or measurement methods, suggesting that no single calculation strategy currently stands out for these highly irregular eyes.
According to the authors, the findings support a broader role for pinhole optics in cataract surgery. They argue that clinical guidelines should be updated to include the use of IC-8 IOL selection for this challenging demographic.
