Prior to cataract surgery the lens must be calculated to appropriately fit a patient for the intraocular lens implant. Lenstar is an optical biometer that calculates the axial length, keratometry, lens thickness, pupillometry, and anterior chamber depth. Dilation drops are routinely used in eye exams in addition to pre-cataract surgery. The dilation drops include Tropicamide 1%, and Phenylephrine 2.5%. The Tropicamide achieves the dilation of the pupil which causes an anterior rotation of the ciliary body, which may affect the Lenstar measurements. This study is to determine if dilating medications affect the lens power prediction for emmetropia by the Lenstar biometer. Prior to dilation, Lenstar biometry will be performed on each eye. Patients will receive dilation medication and after waiting 20 minutes Lenstar biometry will be performed on each eye. Dilation and measurement with Lenstar will be done as standard of care. Measurements and calculations from before and after will be compared.

Inclusion Criteria:

• Candidates for cataract surgery undergoing routine evaluation of cataracts.

Exclusion Criteria:

• Patients that have had their cataracts removed
• Patients that cannot undergo routine evaluation for cataract surgery (because they are too ill to sit upright in a chair)