The intervention supplement consisted of marigold extract, zeaxanthin, elderberry extract, bilberry extract, lycopene extract, multivitamin, silicon dioxide, inulin, and dextrose monohydrate, all in powder form and packaged in individual sachets (Twinkle Eyez™; Xmegami, Selangor, Malaysia). Each sachet contained 4.6 mg of lutein and zeaxanthin and 15.4 mg of elderberry extract.

Ocular Surface Disease Index (OSDI) was used to assess the ocular health of participants. The OSDI, a validated 12-item questionnaire, assesses three subcategories: ocular symptoms, vision-related function, and environmental triggers. Each item is rated on a scale from 0 ('none of the time') to 4 ('all of the time'), with the final OSDI score calculated by summing the participant's responses

Visual Analogue Scale (VAS) was used to assess the ocular health of participants. The VAS is a psychometric measuring instrument designed to document the characteristics of disease-related symptom severity or general wellbeing of an individual, often used in epidemiological and clinical research. Participants were asked to self-rate their current overall ocular health using a 10 cm VAS, where 0 indicated a very poor condition and 10 indicated an excellent condition.

Immune Status Questionnaire (ISQ) and Visual Analogue Scale (VAS) was used to assess the immunity status of participants. The ISQ consists of seven items that assess the occurrence of various immune-related symptoms in the past. The total ISQ score was recoded onto a scale from 0 (very poor) to 10 (excellent).

Visual Analogue Scale (VAS) was used to assess the immunity status of participants. The VAS is a psychometric measuring instrument designed to document the characteristics of disease-related symptom severity or general wellbeing of an individual, often used in epidemiological and clinical research. Participants were asked to self-rate their current overall immunity status using a 10 cm VAS, where 0 indicated a very poor condition and 10 indicated an excellent condition.

Dietary intakes of lutein and zeaxanthin over the previous six months were assessed using a validated, simplified food frequency questionnaire (FFQ) tailored to include 30 food items known for their lutein and zeaxanthin content (1). For each food item, a specific serving size was provided, and participants reported their consumption frequency in terms of 'never' or the number of occasions per day, week, or month, as appropriate. The dietary intake of lutein and zeaxanthin was then calculated based on values from the United States Department of Agriculture-National Cancer Institute Carotenoids Database.