The World Health Organization recently released its first "World Vision Report," pointing out that the number of people with visual impairment or blindness worldwide exceeds 2.2 billion, of which at least 1 billion cases were preventable or have yet to be addressed.

We often say "protect the environment like we protect our eyes," "cherish our brand like our eyes," but do we truly take good care of our eyes?

Which of our caring habits are right, and which are actually harmful?

Cai Jianqi from the Vision Health and Safety Protection Laboratory of the China National Institute of Standardization explains that their research focuses on the biological mechanism of light on the human body, making the abstract concept of "health" concrete and standardized through objective and quantitative methods.

Guest speaker: Cai Jianqi, Director of the Vision Health and Safety Protection Laboratory, China National Institute of Standardization, Researcher.

1 About "Visual Fatigue"

The description of "visual fatigue" is too subjective; we have quantified it.

When discussing eye health, visual fatigue is a frequent topic. Many products (displays, lighting, glasses, eye patches) claim to be "anti-fatigue" or "comfort-enhancing."

But what is the mechanism of visual fatigue? How can it be quantified? How effective are products in relieving visual fatigue? Few can answer these questions clearly.

Traditional evaluations rely on subjective feedback, for example, having a dozen people read under a lamp and then rate their feelings – this is easily influenced by mood or environment, leading to inaccurate and unstable results.

International product assessments have the same flaw: they can only say whether you feel tired, not the degree of fatigue. So we should not blindly trust foreign "anti-fatigue" products.

Our laboratory began systematic research on visual fatigue in 2011. Through visual physiological experiments on nearly 10,000 people, we established a quantitative visual fatigue evaluation model (VICO – Visual Comfort Index) integrating visual imaging quality, ciliary muscle regulation, and individual eye structure differences.

VICO is a model tailored to the Chinese population (yellow race) and objectively quantifies the impact of lighting, displays, and glasses on visual fatigue.

2 About Classroom Lighting

We, the yellow race, need more and stronger light.

As of June this year, China's VICO evaluation indicators have been highly recognized by ISO, CIE, and ISA, and have formed multiple national and international standards. For yellow race eyes, a product with VICO value lower than 2 is considered truly eye-protective.

For classroom lighting, the current Chinese national standard requires desktop illuminance >300lx, based on ISO 8995-1 (which is based on Caucasian physiological characteristics). However, Chinese people (yellow race) differ significantly: pupil size is about 3-5mm (vs. 6-8mm in Caucasians), and the melanin in dark eyes is much more light-tolerant than blue/green eyes. Therefore we need more light.

Our VICO yellow‑race model gives the answer: 500-750lx illuminance, which minimizes visual fatigue and is optimal for Chinese eyes. This finding has been adopted by ISO into the revised ISO 8995 standard, and also included in China's myopia prevention national standard.

3 About High Myopia

Parents should pay attention to whether children's axial length grows too fast.

In August 2018, eight ministries including the Ministry of Education and National Health Commission issued the "Comprehensive Plan for the Prevention and Control of Myopia in Children and Adolescents." However, there are special points to note.

Myopia is generally divided into corneal myopia and axial myopia. Axial myopia often leads to high myopia. Normal axial length is about 24-24.5mm; each 1mm increase equals about 300 degrees of myopia. People with axial length exceeding 26mm and myopia over 600 degrees are considered high myopia.

Data from recent years show that the tendency for high myopia among Chinese adolescents is very obvious. During visual function examinations, corneal curvature and axial length must be measured. If a pre-adolescent child's axial length exceeds 24.5mm, parents need to take intervention measures to prevent progression to high myopia.

Why focus on axial myopia and high myopia? Because excessive axial elongation stretches and thins eye tissues, potentially causing fundus damage, retinal tears, detachment, macular degeneration, and even blindness.

Parents should take children for checkups twice a year: axial length and corneal refraction. If axial length grows too fast, various interventions are needed.

There are many misconceptions about glasses. Some parents ask children to wear glasses only in class and take them off after school – but constantly switching between distance and near vision aggravates eye fatigue and accelerates myopia progression, converting corneal myopia into axial myopia.

4 About Refraction

First-time refraction for adolescents must use cycloplegic refraction (dilated pupils).

Besides measuring corneal curvature and axial length, the first refraction for adolescents must use cycloplegia. Many children under 12 have extremely strong ciliary muscle adjustment – a child may be hyperopic in the morning but become myopic in the afternoon when tired. Cycloplegia (paralyzing the ciliary muscle) accurately measures true refractive status. Without it, computer refraction can easily be inaccurate, misdiagnosing pseudomyopia as true myopia. Therefore, cycloplegic refraction is mandatory for the first eye exam in youth.

5 About Myopia Prevention

Outdoor sports with natural light are very important; indoor exercise cannot replace outdoor activity.

Natural light is key. For thousands of years before the industrial age, humans lived in changing light environments, and adaptation to natural light is in our genes. In nature, we mostly look into the distance. High myopia incidence is largely due to excessive near work. In nature, we engage in distance viewing, and natural light triggers photochemical reactions in ocular tissues, strengthening the sclera and inhibiting axial elongation – producing a huge effect in controlling myopia.