Development of a validated computer-based instrument (software program) for the assessment of intermediate visual acuity (IVA). It is known that no validated method for the evaluation of IVA exists.~Primary objective of the study is to validate a specific computer-based chart (optotype) that will enable: a) comparative studies among different groups of presbyopic patients with refractive errors (ie. myopia, hyperopia, and/or astigmatism), and, b) assessment of the efficacy of surgical refractive procedures (ie. LASIK) on presbyopic patients.~Intermediate Visual acuity chart is similar to the prevalent Jaeger chart. It consists of short blocks of text in various type sizes.The computer screen is set at a specific reading distance (1 meter) and the patient is asked to read the passage with the smallest type he/she can see. According to the smallest text he/she can read, IVA is classified from IVA1 (which is considered the equivalent of 20/20 distance visual acuity) to IVA5~Validation of the computer-based IVA chart will be done by correlating the results of the IVA chart to the corresponding ones from the validated 20/20 distant and Jaeger near visual acuity charts, in a random sample of study participants with different refractive errors and different near and distant visual acuities.
Development of a validated computer-based instrument (software program) for the assessment of intermediate visual acuity.