A new validated ophthalmic patient questionnaire for cataract and lens surgery CLOQ: cataract and lens ophthalmic questionnaire

Background: The new patient cataract and lens ophthalmic questionnaire (CLOQ) determines subjective patient satisfaction before and after cataract surgery according to item response theory (IRT). Methods: A total of 317 patients with bilateral cataract surgery and implantation of different intraocular lens (IOL) types were included. The questionnaire (37 questions) is divided into questions on visual acuity-relevant quality of life (VRQoL), quality of vision (QoV), spectacle dependence, and general satisfaction. For all questions, five response categories are available. Analysis is performed by determining the model parameters/item characteristic curves. Testing of the model is performed by expected score curves, infit/outfit statistics, and determination of reliability and Cronbach's alpha. Results: The IRT analyses for the QoL and QoV questions showed 1. a clear order of threshold parameters in the multilevel response scale; 2. a good fit of the response model of the empirical and the expected score curves; 3. unidimensionality, with values of < 1 for the mean square in- and outfit statistics; and 4. reliability of FWLE = 0.87 and 0.71, respectively. The post-surgical improvement is clearly evident in the higher person parameters, spectacle dependency, and better visual acuity. Conclusion: Standard calculations were performed for model parameters, model tests, and reliability based on a partial credit model. The results confirm the suitability for evaluation of subjective patient satisfaction.