WS/T 663-2020 in English

As the first health industry specification in my country specifically for refractive error screening among primary and secondary school students, this standard systematically stipulates the use standards of equipment such as ophthalmometers and mirror strings, as well as the complete process from screening preparation to result processing. The technical points are mainly reflected in three aspects:

• Standardization of screening methods: clarify the detection requirements under non-ciliary muscle paralysis conditions
• Quality control system: establish quality control nodes such as instrument calibration and averaging of multiple measurements
• Graded referral mechanism: accurate referral threshold based on equivalent spherical power (SE)

1. Preparation before screening

Special attention should be paid to the special treatment of orthokeratology lenses wearers: Night wearers are exempt from refractive testing, but the visual acuity with glasses must be recorded. The screening site should meet the following requirements:

1. 5-meter straight-line distance from the visual acuity chart
2. Environmental noise <55 decibels
3. Optometre operating temperature 18-28℃

2. Operational specifications

Emphasis on the use of ophthalmometer:

• Daily correction with a standard simulated eye
• Cylinder value set to negative state
• Fluctuation > 0.50D requires a note

The standard innovatively established a three-level referral mechanism:

1. Observation and follow-up: naked eye visual acuity ≥4.9 and SE ≥0.00D
2. Early Warning Review: Elementary school students with SE <+2.00D or astigmatism ≥1.50D
3. Emergency Referral: Middle school students with SE <-0.50D or SE >+3.00D

Special Case Handling: Wearers of contact lenses are required to take off their lenses and test them 30 minutes later

Compared with previous standards, this standard has the following major breakthroughs:

• Technology Integration: The ISO ophthalmometer standard and the domestic vision examination standard are integrated for the first time
• Process Innovation: Establish a three-level prevention and control system of "screening-early warning-referral"
• Data Standardization: It is mandatory to retain two decimal places to improve data comparability

Typical case: After Shanghai adopted this standard, the accuracy of myopia warning increased by 37%