12-month results with small-aperture IOL providing patients with an extended range of vision
Benefits of the IC-8 IOL
This IOL is an excellent option for a wide variety of patients, from basic presbyopic patients to challenging cases, because it works well in ametropic, emmetropic and post-LASIK presbyopes as well as monofocal pseudophakic patients. Additionally, vitreoretinal surgery can easily be performed in eyes implanted with the IC-8 IOL.1–3 It has also been reported to aid in reducing light sensitivity and spectacle dependence.4
One of the most significant benefits was discovered when we found that the pinhole effect blocks the degradation of vision from a corneal astigmatism of up to 1.5 D. In initial surgeries, we realised that, even in refraction, with 1.0 to 1.2 D of astigmatism, the patient was seeing 20/25 uncorrected.
The aperture enables astigmatism tolerance within this range. As astigmatism increases beyond 1.5 D, distance vision degrades proportionally as it does with any lens and it becomes necessary to use a toric or monofocal lens. However, for a patient with 1.5 D or less, which fortunately encompasses most of my patients, I use the IC-8 IOL.
When we operate, we cannot predict if we will induce or change astigmatism. We may induce more, or the axis may change, along with a host of other unpredictable issues. With most multifocal IOLs, a deviation of more than 0.50 D from the intended refractive target will result in the loss of one or two lines of uncorrected distance visual acuity (UDVA).
Another substantial benefit of the IC-8 IOL is its ability to tolerate ±1.00 D manifest refractive spherical equivalent deviation from the intended refractive target, with no appreciable change in acuity, at all distances.
The forgiveness in terms of astigmatism and refractive target, and the spherical nature of the lens, combine to make a greatly simplified cataract procedure. During toric lens implantation, the IOL power must first be calculated along with any corneal astigmatism. Then the axis is determined and marked both at the slit lamp and intraoperatively. Lens extraction is performed, and the IOL inserted and rotated into position.
There is no guarantee that the target will be reached or that the lens will stay in position, and even the smallest degree of rotation could considerably affect the effectiveness of the astigmatism correction. With the IC-8 IOL, these concerns are not present. The IOL power is calculated, the lens extracted, and the IOL inserted and rotated into position.
This is a wonderful feature, especially for patients who have had previous LASIK or have other issues, such as corneal aberrations or a previous radial keratotomy, which can make it difficult to compute power. Using the IC-8 IOL gives me much greater confidence in my outcomes, knowing that even if the target is off in terms of refraction, cylinder or sphere, the small aperture is forgiving and can mask the effect.