Basic ophthalmology knowledge

Vision Facts

In 2020 in Ghana, there were an estimated 3.2 million people with vision loss. Of these, 100,000 people were blind. Source: IAPB

Know your health care professionals.

Allied ophthalmic personnel

Typically, allied ophthalmic personnel comprise opticians, ophthalmic nurses, orthoptists, ophthalmic and optometric assistants, ophthalmic and optometric technicians, vision therapists, ocularists, ophthalmic photographer/ imagers, and ophthalmic administrators.


Ophthalmologists are medical doctors who have been trained in ophthalmic medicine and/or surgery and who evaluate and treat diseases of the eye.


Optometrists are the primary healthcare practitioners of the eye and visual system who provide comprehensive eye and vision care, which includes refraction and dispensing, detection/diagnosis and management of disease in the eye, and the rehabilitation of conditions of the visual system.

Vision impairment, distance
The International Classification of Diseases for distant vision impairment is as follows.

For characterizing binocular vision impairment, vision acuity should be measured with both eyes open with presenting correction if any. For characterizing monocular visual impairment, visual acuity should be measured monocular with presenting correction if any.

Level of vision impairment Visual acuity scale
6m 20ft Decimal
Mild <6/12 but ≥6/18 <20/40 but ≥20/70 <0.5 but ≥0.3
Moderate <6/18 but ≥6/60 <20/70 but ≥20/200 <0.3 but ≥0.1
Severe <6/60 but ≥3/60 <20/200 but ≥20/400 <0.1 but ≥0.05
Blindness <3/60 <20/400 <0.05

Vision impairment, near
The International Classification of Diseases classifies near vision impairment as presenting near visual acuity worse than N6 at 40cm with existing correction.

Vision loss
According to VLEG, vision loss is habitual distance or near vision impairment, which may be permanent or treatable.