Measurement of power quality and MTF of intraocular and soft contact lenses in wet cells

摘要

Abstract: The need to measure the optical properties of IOLs in a wet cell stems from the required in- situ conditions. Soft contact lenses also benefit from wet conditions since the blotting procedure introduces significant errors. An instrument with a high degree of accuracy is needed to compensate for the reduced sensitivity due to the small refractive index difference between the lens and saline. An optical setup based on a new deflectometer module with continuous tuning of shear and tilt provides the necessary resolution and flexibility. Various optical properties can be evaluated from the fringe pattern: Power and cylinder distributions across the lens, aberrations, OTF curve, through focus MTF, and others. A criterion for determining the lens quality may be derived from the power distribution, from the full MTF curve or from the through power MTF. The width of the through power MTF curve relative to the resolution of the visual system is a good quality criterion, while the maximum provides a repeatable outcome for the overall power or cylinder. A single measurement yields both power and MTF of intraocular lenses immersed in a model-eye type wet cell. Arbitrary values of spatial frequency and pupil size up to the full diameter of the IOL can be selected. !11