The purpose of this study is to evaluate the visual performance of a trifocal intraocular lens at distance, near and intermediate viewing, by way of visual acuity measurement, contrast sensitivity.

Patient satisfaction and quality of vision will also be assessed by way of a questionnaire.

Monocular and Binocular Unaided (UCVA) and Best Corrected Visual Acuity (BCVA) will be measured at 6m in LogMAR units under photopic conditions (85cd/m2).

Subjective Refraction will be performed to establish any residual refractive error will for distance, intermediate and near.

Defocus Profiles (visual acuity over imposed defocus) are measured for each patient. The patient observes the 6m LogMAR chart through best distance correction, then defocusing is achieved by the addition of pairs of lenses from +2.00D to -4.00D in 0.50D steps.. The LogMAR acuity will be recorded and the data plotted.

Contrast Sensitivity will be evaluated monocularly under photopic (85cd/m2) conditions and mesopic (4cd/m2) using the Pelli-Robson Contrast Sensitivity Chart.

Near and intermediate performance will be evaluated using the Radner Reading Charts to assess acuity (LogRAD units) and reading speed in photopic conditions 85cd/m2

Inclusion Criteria:

• Age 40-70yrs
• Bilateral implantation of a trifocal intraocular lens

Exclusion Criteria:

• existing ocular pathology
• surgical complications
• corneal astigmatism > 1.50DC

Patients from a private ophthalmology clinic