Assessment

Method

Classification of Abnormality

Source

Visual acuity

Snellen chart

Normal = 6/12 or better; abnormal = worse than 6/12

 [29]

Color vision

Ishihara plates (24-plate edition)

Normal = fewer than 3 errors; abnormal = 3 or more errors

 [30]

Pupillary reaction

Penlight examination

Normal = brisk, direct, and consensual reaction; abnormal = sluggish or absent reaction

 [31]

Intraocular pressure

Schiotz tonometer

Normal = ≤ 21 mmHg; abnormal = >21 mmHg

 [32]

Fundoscopy

Direct ophthalmoscopy

Normal = no optic nerve or retinal abnormalities; abnormal = any abnormality noted

 [33]