Abstract Cataract occurs when the lens loses its transparency thereby scattering or absorbing light that visual acuity is compromised. Worldwide, Cataract is the most common cause of blindness and visual impairment. It may occur at any age and babies may be born with congenital cataract. Cataract can also be caused by eye injury. Cause of cataracts is not known. Data from epidemiological and case-control studies have suggested various risk factors, among them, sunlight, diabetes, diarrhoea, smoking and alcohol. Opacities of the lens are one of the most common causes of blindness today. Data given by the World Health Organisation reveal that more than 40 million people are blind, half of which are blinded by cataract. In the western world the incidence of cataract in adults older than 50 years is 15% the incidence in the developing countries is far higher and in India, reaches 40%. Therefore, identification and early treatment of cataract is crucial.1 A cross-sectional study was conducted to assess the knowledge regarding cataract among adults aged 40 years and above attending different OPDs in tertiary care centre of North East India in August 2025. A structured knowledge-based questionnaires was used to collect data from 180 participants attending different OPDs who were selected using consecutive, sampling technique. Analysis was done using descriptive and inferential statistics (chi-square). Out of 180 participants majority of them, 110(61.1%) had average knowledge regarding cataract, 26(14.4%) had poor knowledge and 44(24.4%) had good knowledge. From the study, it is found that there is no association of knowledge of the participants regarding cataract with age, gender, occupation, education, religion, except there is a significant association of knowledge with their place of residence.