Does the Spot (Autorefractor) overestimate cylinder power or other refractive errors in certain subpopulations, such as young children or individuals with dark irides?

From the Guidelines

Spot Vision Screeners are known to overestimate cylinder power in certain subpopulations, particularly in young children and individuals with dark irides. The device's accuracy can be affected by various factors, including pupil size, iris pigmentation, and fixation quality, which can lead to overestimation of astigmatism and hyperopia, while underestimating myopia in young children 1. Some key points to consider when interpreting Spot screening results include:

• The device may indicate higher levels of astigmatism than actually present in children under 3 years of age
• Spot tends to overestimate hyperopia while underestimating myopia in young children
• Reduced accuracy in patients with very dark irides due to challenges in pupil detection and light reflection patterns
• Difficulty obtaining accurate measurements in children with small pupils or certain ocular conditions like nystagmus These measurement discrepancies occur because photorefraction technology, which Spot uses, relies on light reflection patterns that can be affected by pupil size, iris pigmentation, and fixation quality 1. Clinicians should consider these potential biases when interpreting Spot screening results, especially in very young children or those with dark irides, and follow up with comprehensive eye examinations when results are borderline or when clinical suspicion remains despite normal screening results 1.

From the Research

Refractive Error Measurement in Subpopulations

• The accuracy of autorefraction in measuring refractive errors in subpopulations, such as young children and individuals with dark irides, has been evaluated in several studies 2, 3, 4, 5, 6.
• In children, noncycloplegic autorefraction has been found to overestimate myopia and result in a high error rate for emmetropic and hyperopic refractive errors 5.
• Cycloplegic autorefraction is more sensitive than noncycloplegic autorefraction in measuring refractive errors, especially in children and young adults 4.
• The difference between cycloplegic and noncycloplegic refractive error is associated with factors such as age, intraocular pressure, and uncorrected visual acuity 5, 6.

Specific Subpopulations

• In young children (less than six years old), autorefraction may not be reliable and should be corroborated with retinoscopy 2.
• In school-aged African children, noncycloplegic autorefraction may accurately detect astigmatism and myopia, but may elicit higher myopic values and lower hyperopic values than cycloplegic refraction 3.
• In Chinese children and adolescents, lack of cycloplegia in refractive error measurement is associated with significant misclassifications in both myopia and hyperopia 6.

Refractive Error Types

• Myopia: noncycloplegic autorefraction may overestimate myopia in children and adolescents 5, 6.
• Hyperopia: cycloplegic autorefraction is more sensitive than noncycloplegic autorefraction in measuring hyperopia, especially in children and young adults 4.
• Astigmatism: noncycloplegic autorefraction may accurately detect astigmatism in school-aged African children 3.