Vision Loss

Change the Definition of Blindness

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INTRODUCTION
The categorization of visual impairment currently in use worldwide is based on
the ICD 10th Revision 1st and 2nd edition. This is derived from a WHO Study
group on the Prevention of Blindness that was convened in 1972 to provide a
standardized definition. This was to facilitate the collection of population based
data on prevalence of vision impairment and blindness in a uniform and
comparable manner. At the time of this meeting four major causes of vision loss
had been identifie

d. These were Trachoma, Onchocerciasis, Xerophthalmia and
Cataract. There was no consideration of refractive error as an underlying cause
of visual impairment, if not blindness.
CASE FOR REVISION
There are five issues that dictate the need for consideration of a revision of the
current definition and categorization. These are:
(1)The definition of visual impairment categories based on “best corrected” vision
(2)The nomenclature
(3)The categorization of BLINDNESS
(4)The inconsistencies within H 54 subcategories
(5)The ICO Resolution on Revision of ICD 10
Recommendations of WHO Consultation on “Development of Standards for
Characterization of Vision Loss and visual functioning “
(1)Definition of Visual Impairment and Blindness
The currently used definition includes the term “best Corrected Vision” in the
better eye.
The methodology followed for measuring visual acuity, particularly in population
based studies, is to use a “pin hole” in patients whose “presenting“ vision is
below a certain cut off point (currently 6/18). Many recent studies have shown
that the use of “best corrected” vision overlooks a large proportion of persons
with visual impairment, including blindness, due to uncorrected refractive error, a
common occurrence in many parts of the world.
Uncorrected refractive error is now considered to be a major cause of visual
impairment and estimations are under way to calculate the loss in terms of
DALYs (disability-adjusted life years) resulting from this cause.
The correction of refractive error is a cost effective intervention and is one of the
priorities under the disease control component of the Global Initiative for the
Elimination of Avoidable Blindness (VISION 2020, the Right to Sight). 2
(2)Nomenclature
The current ICD uses the words “LOW VISION” for categories 1, 2 and 3 of
Vision impairment.
In the practice of eye care “LOW VISION” has a specific meaning as defined by
WHO.
This is as follows:
”A person with low vision is one who has impairment of visual functioning
even after treatment and/or standard refractive correction, and has a visual
acuity of less than 6/18 to light perception, or a visual field of less than 10
degree from the point of fixation, but who uses, or is potentially able to use,
vision for planning and/or execution of a task. “
Under this definition persons who would benefit from low vision care also exist
among those who are currently categorized as blind. This has led to
miscalculations in the estimation of persons requiring LOW VISION care.
(3)Definition of Blindness
The current definition does not make a distinction between those who have
“irreversible” blindness (NO perception of light) and those that have light
perception but are still less than 3/60 in the better eye.
The management of these two categories is different and categorization based
on this would be useful.
(4)Inconsistencies in H54 subcategories
The sub categories of H54 have inconsistencies when describing “Monocular
vision impairment” and “Monocular Blindness”; the fellow eye in these needs not
necessarily to be “normal”. To add clarity to the sub-categories it is proposed to
replace the current table (ICD – 10th Revision see below). 3
RECOMMENDATIONS
(1)The words “best corrected” be replaced by “presenting” in a revised definition
(2)Delete the term LOW VISION from the current ICD 10 definition to collectively
describe categories of visual impairment 1, 2 and 3
(3)Categories as shown in the revised Table.1.
(4) The wording in the H54 subcategories be changed as follows in line with the
proposed revised categories
H54.- Visual impairment including blindness (binocular or monocular)
Note: For definition of visual impairment categories see table below.
Excludes: amaurosis fugax (G45.3)
H54.0 Blindness, binocular
Visual impairment categories 3, 4 & 5
H54.1 Severe visual impairment, binocular
Visual impairment category 2
H54.2 Moderate visual impairment, binocular
Visual impairment category 1
H54.3 Mild or no visual impairment, binocular
Visual impairment category 0
H54.4 Blindness, monocular
Visual impairment categories 3, 4, 5 in one eye and categories 0, 1, 2 or 9 in the
other eye.
H54.5 Severe visual impairment, monocular
Visual impairment category 2 in one eye and categories 0, 1 or 9 in other eye
H54.6 Moderate visual impairment, monocular
Visual impairment category 1 in one eye and categories 0 or 9 in other eye
H54.9 Unspecified visual impairment (binocular)
Visual impairment category 9
Note: The table below gives a classification of severity of visual impairment
recommended by the Resolution of the International Council of Ophthalmology
(2002) and the Recommendations of the WHO Consultation on “Development of
Standards for Characterization of Vision Loss and Visual Functioning” (Sept 2003)
For characterizing visual impairment for codes H54.0 to H54.3, visual acuity
should be measured with both eyes open with presenting correction if any. For
characterizing visual impairment for codes H54.4 to H54.6, visual acuity should
be measured monocularly with presenting correction if any. If the extent of the
visual field is taken into account, patients with a visual field of the better eye no
greater than 10° in radius around central fixation should be placed under
category 3. For monocular blindness
(H54.4), this degree of field loss would apply to the affected eye. 4
Table 1 Proposed revision of categories of visual impairment
Presenting distance visual acuity
Category Worse than: Equal to or better than:
Mild or no visual
impairment
0
6/18
3/10 (0.3)
20/70
Moderate visual
impairment
1
6/18
3/10 (0.3)
20/70
6/60
1/10 (0.1)
20/200
Severe visual impairment
2
6/60
1/10 (0.1)
20/200
3/60
1/20 (0.05)
20/400
Blindness
3
3/60
1/20 (0.05)
20/400
1/60*
1/50 (0.02)
5/300 (20/1200)
Blindness
4
1/60*
1/50 (0.02)
5/300 (20/1200)
Light perception
Blindness
5
No light perception
9 Undetermined or unspecified
* Or counts fingers (CF) at 1 metre.
Note: The term visual impairment in category H54 comprises category 0 for mild
or no visual impairment, category 1 for moderate visual impairment, category 2
for severe visual impairment, categories 3, 4 and 5 for blindness and category 9
for unqualified visual impairment. The term “low vision” included in the previous
revision has been replaced by categories 1 and 2 to avoid confusion with those
requiring low vision care.
Revise category title in Volume 2, page 126, ICD-10 2nd edition:
Chapter VII: Diseases of the eye and adnexa
H54.- Visual impairment including blindness (binocular or monocular)
This code is not to be used as the preferred code for the “main condition” if the
cause is recorded, unless the episode of care was mainly for the blindness itself.
When coding to the cause, H54.- may be used as an optional additional code.
Revise codes and add subterms in Volume 3:
Blindness (acquired)(congenital)(both eyes)(binocular) H54.0
….
– hysterical F44.6
– mind R48.8
– monocular H54.4
– night H53.6 5
– – vitamin A deficiency E50.5
– one eye (other eye normal) H54.4
– – low vision, other eye H54.1H54.4
Defect, defective
– vision NEC H54.9
Impaired, impairment (function)
….
– tolerance, glucose R73.0
– vision NEC H54.9
– visual
– – binocular H54.9
– – – mild H54.3
– – – moderate H54.2
– – – severe H54.1
– – monocular
– – – moderate H54.6
– – – severe H54.5
Poor

– urinary stream R39.1
– vision NEC H54.9
Problem (related to)(with)

– sight H54.9
Vision, visual
– binocular, suppression H53.3
– blurred, blurring H53.8
– – hysterical F44.6
– defect, defective NEC H54.9
….
– halos H53.1
– loss H54.9
– – both eyes H54.3H54.1
– – complete, with or without light perception— see Blindness
– – one eye H54.5
– – sudden H53.1
– low (both eyes) H54.2
– – one eye (other eye normal) H54.6
– – – blindness, other eye H54.4
– perception, simultaneous without fusion H53.3