The Incidence Of Toric Intraocular Lens (Iol) Implantation In Naïve Cataract Eyes, When Tomography-Derived Total Corneal Cylinder Is Used And 0.5 Diopter With-The-Rule Is Targeted: A Consecutive Case Series Of 1250 Eyes.

Refractive accuracy of novel use of keratometry data of total corneal cylinder as measured by Scheimpflug tomography-to include anterior and posterior central 5mm corneal power-and use of toric IOL powers from +1 to + 6 Diopters was evaluated in a large case series for safety and efficacy

LaserVision Ambulatory Eye Surgery Unit, Athens, Greece

In 1250 consecutive clear corneal cataract cases over 5 years by one surgeon (AJK), we used 2 types of IOLs: the Acrysof SN60WF (a spherical-power-only aspheric hydrophobic acrylic lens and the it’s  toric equivalent: the SN6AT (toric powers T2 to T9). Central 5mm total corneal power as measured with Scheimpflug tomography was used in all cases for keratometry data along with the Lenstar interferometer axial length, while targeting 0.50 Diopters with-the-rule postoperative refractive astigmatism via the Alcon toric IOL calculator. The Hoffer-Q and Holliday 1 formulas were used dependent on anterior chamber depth and mean keratometry value.  Postoperative clear-cornea cataract surgery UDVA, CDVA and refraction were evaluated up to 12 months

In 1025 (82%) of the eyes were implanted a SN6AT toric IOL, while 225 (18%) with a non-toric SN60WF. Of these SN6AT lenses used the toric power was specifically: 67% : T2 and T3 (cylindrical power: +1 and +1.5 D), 20% T4 to T5 (powers +2.25 to 3 Diopters) and 8% T6 to T7 (power +3.75 and +4.50 Diopters) and final 5% T8 and T9 (powers +5.25 to +6 Diopters) respectively. Residual refractive astigmatism was up to 0.5 Diopters in 89% of cases by month 3. Mean preop  UDVA changed from 20/400 to 20/32 postop, CDVA: from 20/50 to 20/24. The average postoperative spherical refraction change from pre- to postop in Diopters: sphere: -4.5 (-12.50 to +5.5) to -0.50 (+0.50 to -1) and cylinder: +2.5 (+5.5 to +0.25) to +0.55 (plano to +0.75) respectively.

When targeting a slight with-the-rule postoperative astigmatic outcome in clear cornea cataract surgery and when keratometric values used derive from total corneal central 5mm measurements with Scheimpflug tomography, the majority of naïve eyes undergoing clear corneal cataract surgery can benefit from the use of an even lower power toric IOL. These data are very different of the peer-reviewed published practices internationally, that are usually based on astigmatic measurements from manifest refraction and/or central up to 3mm anterior keratometry pre-operative data