OVERVIEW
OF BLINDNESS

DEFINITION

Blindness is defined as
visual acuity of 3/60 or worse or visual field of 10 degrees from fixation or
worse in the better eye.

There are four levels of visual function, according to the International
Classification of Diseases -11 (by WHO): Using visual acuity in the better eye

          

*<10 degrees central visual field is equivalent to ‘Blind’

 – Mild visual impairment (6/12 –
6/18) was recently introduced

 – Moderate visual impairment
combined with severe visual impairment are grouped under the term

   “low vision”

 – Low vision taken together with
blindness represents all visual impairment.

CAUSES OF BLINDNESS IN
NIGERIA

1.    
Avoidable blindness is blindness
attributable to causes that can be treated or prevented. In sub-Saharan Africa
accounts for about 80% of the causes of blindness according to WHO estimates.

Avoidable blindness is
broadly divided into treatable (70.8%) and preventable (13.2%). According to
the Nigerian national blindness and visual impairment study (NNBVIS),
avoidable blindness accounts for 84.0% of blindness.

Treatable causes-

·       
Cataract 43.0%,

·       
Glaucoma 16.7%,

·       
Uncorrected aphakia 8.4%,

·       
refractive error 1.4%,

·       
PCO 0.2%,

·       
Diabetic retinopathy 0.5%,

·       
Pterygium (0.5%).

Preventable causes: –

·       
Trachoma 4.2%,

·       
Oncho 1.1%,

·       
other corneal scars 7.9%

·       
Other corneal scars include Vit-A
deficiency, Measles keratopathy and TEM.

                               

             

2.    
UNAVOIDABLE

·       
Absent globe/phthisis bulbi 2.3%

·       
Macular degeneration 1.8%

·       
Optic atrophy 3.7%

·       
Other posterior segment diseases 3.0%

The strategies are
targeted towards the specific diseases

·       
like scaling up cataract uptake by
tackling all the barriers to cataract surgery for example.

·       
Immunization for measles, dietary
supplementation for Vit-A def, SAFE for trachoma,

·       
Ivermectin for onchocerciasis,

·       
school eye health for refractive errors
and

·       
distribution of spectacles for presbyopia

·       
screening for diabetic retinopathy by
encouraging eye exams for diabetics

General measures will
involve:

·       
health education,

·       
community awareness,

·       
policy, funding etc

also include community
participation, primary eye care PEC which has to be inculcated into PHC and
social marketing.

Core
strategies

• Disease
control: facilitate the implementation of specific programmes to control
and treat the major causes of blindness.

• Human
resource development: support training of ophthalmologists and other eye
care personnel to provide eye care.

• Infrastructure
and appropriate technology development: assist to improve infrastructure
and technology to make eye care more available and accessible.

 

 DERIVED FROM;

ST JOSEPH’S EYE HOSPITAL MGBIRICHI 

OPHTHALMIC THEATRE COURSE