Table 2

Quality indicators of included instruments

	Visual acuity	Visual field	Ocular alignment	Ocular movement	Quality of life	Functional vision
	LogMAR	Peripheral perimetry	Prism cover test	Rotation grading	VFQ-25	Radner reading
Use in target population	Yes	Yes	Yes	Yes	Yes	Yes
Content validity
Reliability	+	+	+	+	+	+
Responsiveness	+	+	+	+	+	+
Internal consistency	+	+	+	+	+	+
Structural validity	+	+	+	+	+	+
Measurement error	+	+	+	+	+	+
Hypothesis testing	+	+	+	+	+	+
Criterion validity	+	+	+	+	+	+
Cross-cultural validity	+	+	+	+	+	+
Quality of evidence	High	High	Moderate	Moderate	Moderate	Moderate
Feasibility
Patient comprehension	Widely understood	Widely understood	Widely understood	Widely understood	Widely understood	Widely understood
Interpretability	Clear usage	Clear usage	Clear usage	Clear usage	Clear usage	Clear usage
Ease of administration	High	Relative	High	High	High	High
Length of instrument	Small—small number of lines	Moderate—can take time per eye	Small	Small	Moderate	Moderate
Completion time	Within minutes	15–20 min	Within minutes	Within minutes	Relative	Relative
Patient mental ability level	Low—use with children	Medium	Low	Low	Medium	Medium
Ease of standardisation	High ease	High	High	High	Moderate	Moderate
Clinician comprehension	Widely understood	Widely understood	Widely understood	Widely understood	Widely understood	Widely understood
Type of instrument	Letter chart	Perimeter	Occluder, target, prisms	Occluder, target	Questionnaire	Reading paragraphs
Cost	Low	High	Low	Low	Relative to licence	Low
Required equipment	Letter chart	Perimeter	Occluder, target, prisms	Occluder, target	Questionnaire	Book
Type of administration	Clinician-led	Clinician led	Clinician led	Clinician led	Clinician-led Self-administered	Clinician led
Availability in different settings	Yes	Yes	Yes	Yes	Yes	Yes
Copyright	Per company	Per company	Per company	Per company	Per company	Per company
Patient physical ability level	Minimal	Relative	Minimal	Minimal	Relative	Relative
Regulatory approval	No	No	No	No	No	No
Ease of score calculation	High ease	High ease	High ease	High ease	High ease	High ease

LogMAR, Logarithm of the Minimal Angle of Resolution; VFQ-25, Visual Function Questionnaire 25.