SINGAPORE - The longer a person has diabetes, the more chance he has of developing impaired colour vision, a local study has found.
One in five diabetics who do not have diabetic retinopathy - a diabetic eye disease which can result in vision loss - sees blue colours in a greener shade and finds it difficult to differentiate yellow and red from pink, making it hard for him or her to get jobs in professions like interior design and architecture. In comparison, impaired colour vision affects only an estimated 8 per cent of all men and less than 1 per cent of women worldwide.
This finding stems from a study of 849 patients of different ethnicities. They were aged 21 to 80, and all of them had Type 2 diabetes.
The study, carried out by SingHealth Polyclinics and Singapore Polytechnic from 2013 to 2015, also found that people who are older and have a lower education level are more likely to have colour vision problems. Patients also tend to develop such issues six years after the onset of the disease.
The risk of developing impaired colour vision increases by 7 per cent for each additional year the patient has Type 2 diabetes, the study found.
Yet there is no standard test for colour blindness as part of regular diabetes screening, said Dr Tan Ngiap Chuan, director of research at SingHealth Polyclinics, who is also the lead researcher of the study.
"We already know from other studies that they may be a bit more withdrawn from social life... for chefs, cooking might be a bit difficult because you really need to pick fresh ingredients (based on colour) and it might affect the presentation of the food," he added.
There are several types of impaired colour vision. Blue-yellow colour blindness, known as tritanomaly, was the most common, while red-green colour blindness was less common.
People with impaired colour vision may not be able to see certain colours or have difficulty in telling different shades of a colour apart.
The prevalence of Type 2 diabetes here is expected to rise from 11.3 per cent in 2010 to 15 per cent in 2050. This means that the number of people with impaired colour vision is expected to increase significantly, said Dr Tan.
There is currently no treatment available for diabetic patients with impaired colour vision, said Dr Tan.
"The message is: First, don't develop diabetes; if you've already developed diabetes, get it well controlled so that you will not end up with colour vision defects and other more serious eye complications," he advised.