Optimizing the correction of low corneal astigmatism in cataract patients

Resumen

OBJECTIVE: To analyse the visual quality of patients with low corneal astigmatism implanted with toric, aspheric and spherical intraocular lenses (IOLs). SETTING: FISABIO-Oftalmología Médica, Valencia, Spain. METHODS: Forty-five patients, mean age 73 ± 18 years, with no systemic or ocular conditions who needed a SN60T3 IOL (corneal cylinder ~0.75 D), were implanted with spherical, aspheric or toric IOLs. We measured the uncorrected and best corrected visual acuity (UCVA, BCVA), contrast sensitivity function (CSF) and ocular aberrations three months after surgery. RESULTS: Implantation of a toric IOL reduced the refraction astigmatism by 80%. Aberrations increased in all patients, but while astigmatic aberration decreased with toric IOLs, spherical aberration decreased with aspheric IOLs. The UCVA was better with toric and aspheric IOLs (0.1 logMAR), whereas the BCVA was statistically better with aspheric IOLs compared to spherical (p = 0.05). The CSF was similar under photopic conditions. Under mesopic conditions however, spherical IOLs performed best, while toric lenses produced a decrease in the CSF (p < 0.05). CONCLUSION: In patients with low corneal astigmatism, toric IOLs provide a similar visual performance to aspheric IOLs in photopic conditions. Under mesopic conditions, toric IOLs showed lower contrast sensitivity, probably due to a slight error in the axis position, which increases aberrations.