HOTV cut unnecessary preschool vision referrals compared with tumbling E

Design

Cross-sectional comparison, randomised test order

Population

995 children aged 3 to 15 years in Shanghai

Primary outcome

Mean uncorrected acuity; referral and screening accuracy

Effect

Preschool referral 18.6% vs 31.2%; specificity 0.93 vs 0.79

Tumbling E remains the standard chart for child screening in much of Asia, including India, although HOTV letter matching is recommended for young children. This Shanghai study tested 995 children aged 3 to 15 years with both logMAR charts in random order, with cycloplegic refraction as reference.

Acuity measured about half a line worse with tumbling E, a gap of a full line at age 3 that shrank to a letter or less by age 8. In 183 preschool children, HOTV referred fewer (18.6% vs 31.2%), detected more true cases (true positive rate 0.68 vs 0.44) and had higher specificity (0.93 vs 0.79). In older children the tests performed alike.

Tumbling E asks a young child to understand orientation, which many cannot yet do reliably, so poor scores reflect the task as much as the vision.

• Use HOTV letter matching for children under 8 where available
• Expect tumbling E to underestimate acuity by up to a line at age 3 to 4
• Retest a young child who fails tumbling E with HOTV before referring
• Tumbling E performs adequately from about age 8

Why it matters

School screening programmes relying on tumbling E may be overwhelming eye clinics with false positives.

Don't overread it

A single-city Chinese study; the size of the difference may vary with screener training.

The statistics, in plain English

Specificity of 0.93 versus 0.79 means seven versus 21 false referrals per 100 children without disease.

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