Intraocular lens short wavelength light filtering.

There is increasing interest in the effects of reactive oxygen species ('free radicals') in ageing, both in the body overall and specifically in the eye. Cataract and age-related macular degeneration (AMD) are two major causes of blindness, with cataract accounting for 48 per cent of world blindness and AMD accounting for 8.7 per cent. Both cataract and AMD affect an older population (over 50 years of age) and while cataract is largely treatable provided resources are available, AMD is a common cause of untreatable, progressive visual loss. There is evidence that AMD is linked to exposure to short wavelength electromagnetic radiation, which includes ultraviolet, blue and violet wavelengths. The ageing crystalline lens provides some protection to the posterior pole because, as it yellows with age, its spectral absorption increasingly blocks the shorter wavelengths of light. Ultraviolet blocking intraocular lenses (IOLs) have been the standard of care for many years but a more recent trend is to include blue-blocking filters based on theoretical benefits. As these filters absorb part of the visible spectrum, they may affect visual function. This review looks at the risks and the benefits of filtering out short wavelength light in pseudophakic patients.

Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration.

PURPOSE: To compare the clinical performance of the zero spherical aberration (SA) SofPort LI61AO (AO, Bausch & Lomb) intraocular lens (IOL) to the AcrySof SA60AT (AT, Alcon), which has positive spherical aberration. METHODS: Patients underwent uneventful phacoemulsification with implantation of either an aspheric (AO, n = 19) or spherical (AT, n = 20) IOL. Postoperatively, a 5 mm artificial pupil was positioned in trial frames with the cycloplegic refraction during monocular, mesopic contrast sensitivity (CSF) and low-contrast visual acuity (LCVA) testing with glare. Ocular and corneal wavefront error was determined at 5 mm diameters. RESULTS: Mean CSF scores were better at all frequencies tested for the AO than for the AT group, and achieved statistical significance at 1.5 cpd (p = 0.038) and 6 cpd (p = 0.017). With glare, AO eyes read 30.9 +/- 5.0 low-contrast letters versus 25.2 +/- 6.8 for AT eyes (p = 0.005) (mean DeltaLogMAR = -0.10), while high-contrast acuity and refraction were similar. Eyes implanted with the SA60AT had 43% greater positive spherical aberration at a 5 mm wavefront diameter, with no significant difference in corneal SA between groups. A through-focus analysis demonstrated a similar depth of field, yet a comparatively higher visual Strehl ratio for the aspheric IOL at emmetropia (p = 0.038). CONCLUSION: Eyes with the SofPort Advance Optics neutral aberration IOL demonstrated less spherical aberration and better low-contrast acuity compared to eyes with a spherical IOL, without sacrificing tolerance to defocus. The aspheric IOL showed superior optical and clinical performance, which is most likely due to its surface design.