Introduction: Cataract is the leading cause of blindness and different levels of visual impairment worldwide. It can impact anyone, however, the most affected are developing countries, mainly because of lesser treatment capabilities and lower general availability of surgical treatment. Lack of knowledge about cataract among healthcare workers presents a problem, because it affects our ability to implement preventive measures and perform the appropriate health education. Purpose: The purpose of this thesis is to define cataract and confirm three hypotheses through a meta-synthesis of scientific studies: consuming not enough or too much vitamin C affects cataract development; smokers are at a bigger risk to develop cataracts and the third hypothesis that diabetes is an important factor in cataract development. Methods: A descriptive method was used. We performed a literature review about cataract and meta-synthesis of scientific studies. Literature search methods included COBISS.si portal and different databases, COBIB.si, Cochrane, Cinahl with full text, Medline, Medline plus, Wiley and NIH (National Institutes of Health). Results: Meta-synthesis of clinical and scientific studies was performed using a four-level scale by Eccles and Mason. The highest valued arguments are marked as level I, whilst the lowest are marked with a IV. Meta-synthesis shows that healthy lifestyle plays a very important role in cataracts, because it can affect the development of a cataract as well as cataract progression. All three hypotheses were confirmed: consuming not enough or too much vitamin C affects cataract development, smokers are at a bigger risk to develop cataracts and the last hypothesis that diabetes is an important factor in cataract development Discussion and conclusion: We cannot influence all the risk factors. Most important ones that can be affected include consumption of appropriate vitamin C levels, smoking cessation and correct diabetes treatment. Low level of knowledge about cataracts among healthcare workers presents an obstacle in health education, thus preventing us in implementing preventive measures.