This study provides a structured methodology based on a multi-criteria approach (technique for order of preference by similarity to ideal solution – TOPSIS), which is suitable for supporting hospitals and ophthalmologic centers when selecting the optimum instrument for cataract diagnostics. Purchases of technology in general (not only in healthcare) are a much-discussed issue.?The main task when selecting a diagnostic instrument is to optimize the diagnostic output due to the suitable technical parameters of the instrument, but also with regard to operator user-friendliness. This study considers cataract diagnostics in three main steps: measuring the axial length of the eye with the corresponding calculation; measuring the corneal curvature; and verification measurement of the axial length of the eye complemented by two-dimensional B-scan and ultrasound (UBM -– Ultrasound Biomicroscope) measurements. Within each step, a pair of instruments available on the Czech market was identified and, in each category, ten key criteria were established by an expert group. Weight values for individual criteria were then established with the aid of Saaty's matrix, and costs related to one-year operation as well as other effects entering into the cost-efficiency analysis (CEA) were evaluated with the aid of the TOPSIS method. The new generation of diagnostic instruments, i.e., the IOL Master 700 and Pentacam 70700, are better from the cost-efficiency viewpoint in the first two steps of the diagnostics, while in the third step of the diagnostics, the DGH Scanmate biometer, distinguished by a unique three-star quality-assessment system, has a worse level of cost efficiency than the OTI-Scan 2000.