=Paper=
{{Paper
|id=Vol-1327/11
|storemode=property
|title=The Ontological Treatment of Sight and Blindness
|pdfUrl=https://ceur-ws.org/Vol-1327/icbo2014_paper_43.pdf
|volume=Vol-1327
|dblpUrl=https://dblp.org/rec/conf/icbo/RayCJD14
}}
==The Ontological Treatment of Sight and Blindness==
https://ceur-ws.org/Vol-1327/icbo2014_paper_43.pdf
ICBO 2014 Proceedings
The Ontological Treatment of Sight and Blindness
Patrick L. Ray*, Alexander P. Cox, Mark Jensen, Travis Allen, and Alexander D. Diehl
The State University of New York at Buffalo
Buffalo, NY, USA
*
plray@buffalo.edu
Abstract—There have been relatively few attempts to II. REPRESENTING BLINDNESS ONTOLOGICALLY
represent sight or blindness ontologically. This is unsurprising as
the related phenomena of sight and blindness are surprisingly A. Seeing and Sight
difficult to represent ontologically for a variety of reasons. This Seeing is a relational process in Basic Formal Ontology
paper discusses those reasons, explores the current attempts to (BFO). The process is a relation between an agent who detects
represent sight or blindness, and how these attempts fail at and processes stimuli from the environment (external to the
representing certain types of blindness, viz., color blindness and
agent herself) and the stimulus itself. The process of seeing is
flash blindness. We then explore a possible solution to
representing sight and blindness ontologically. The solution
representational insofar as the agent represents the stimulus in
capitalizes on the resources afforded to one who adopts the some manner (we will leave the nature of this representation to
upper-level Basic Formal Ontology. Roughly, we characterize further examination). The diminishment or cessation of this
sight as a function and blindness as a reduction in the conditions relational process is often characterized as loss of vision or
under which the sight function is realized. blindness. The main subject of this paper will be an
examination of the loss of vision (seeing) in formal ontology.
Keywords—ontology; sight; blindness; function; disposition;
Currently there are very few ontologies that seek to
color blindness; flash blindness; Basic Formal Ontology.
represent blindness. The reasons for this are as follows: first, it
I. INTRODUCTION is rather difficult to characterize an entity via a lack or absence,
which seems to be the case with blindness (the lack of sight)
In its most basic form, blindness is the impairment of visual [2]. Metaphysically speaking, it is unclear whether a lack is
function below a certain threshold. Where this threshold lies ontologically significant. Taking the paradigm case of
varies depending on context. The World Health Organization ontological absence involving material entities, a hole, there
characterizes blindness as visual acuity of less than 20/500 or a does not even seem to be anything to which one can attribute
visual field of less than 10 degrees [1]. In the United Kingdom, characteristics at all. This seems to indicate at least a prima
the Certificate of Visual Impairment characterizes blindness as facie problem with characterizing entities via lacks; if one is
visual acuity of less than 20/400 [1]. In the United States, the defined by a lack, then there are all sorts of things that seem to
American Medical Association characterizes blindness as count at least when it is both a necessary and sufficient
visual acuity of less than 20/200 or a visual field of less than 20 condition. Although a strategy for representing a lack of a part
degrees [1]. This indicates that the standards of blindness vary in the context of anatomy has emerged, it is contentious
across international borders. Furthermore, there are the recent whether such a strategy will translate well for functions
calls by the International Council of Ophthalmology to define (dispositions) as the latter are not material entities [3].
blindness and visual impairment according to their own
standards, at least part of which involve visual substitution Second, blindness does not seem to yield a precise
skills employed by persons [1]. Moreover, visual acuity only definition or even clearly differentiated conditions under which
represents one dimension of blindness. There are other types of it is present or absent. Many cases of blindness are progressive
visual impairments that fall beyond the scope of visual acuity – and it will be exceedingly difficult to determine at which point
such as the ability or inability to differentiate color. Blindness blindness has come into existence. Many cases present in
then has many types and presents in degrees. degrees, which is common with the degeneration of the eye or
apparatuses associated with vision. In addition to these
There are two obvious problems with representing and complications, there is controversy over the threshold for
defining blindness and visual loss. First, different groups use blindness. It is common for publications regarding blindness to
different standards of measurement. Second, different specify which definition of ‘blindness’ they employ [1].
standards of classification can be used while adopting a single
standard of measurement. The primary difficulty arising from Even with these complications regarding blindness, we feel
these problems is that it is exceedingly difficult to gather and it is useful to give a univocal account of the phenomenon for
compare data on blindness and vision related disorders. In purposes of ontological development. Such an account should
addition, there are more complex problems that arise in capture all or a vast majority of the cases of blindness and the
representing blindness in formal ontology. This paper explores various classifications of blindness found in the literature.
the difficulties that arise in representing blindness ontologically Thus, it should remain general and flexible enough to capture a
and proposes a novel solution to these problems. wide range of characterizations yet it should also be rigid
enough as to remain informative and insightful.
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ICBO 2014 Proceedings
There are many types of blindness. It is also the case that sensitive or both). We favor the view that the term ‘blindness’
blindness can be defined relative to a context. For example, denotes a single phenomenon reflecting severe visual
there is color blindness and change blindness, which both seem impairment relative to a particular context of evaluation. Thus,
to be types of blindness themselves. An individual might be ‘blindness’ denotes an ontologically well-formed category.
legally blind but still be able to detect some light stimulus – or
Attempts to characterize blindness using current ontologies
one might be blind enough to be prohibited from flying a jet
aircraft but not blind enough to be prohibited from driving. In yields the results listed in table 1.
this way, we might say that someone is ‘blind according to [x]’ B. Some Preliminary Distinctions
where [x] is some standard of evaluation for sightedness. In According to the framework we have adopted, functions
this sense it can be said that blindness comes in degrees. The are a type of disposition. Functions are realizable entities that
extent to which someone has a lack of sight or cannot see will are realized in processes (what are sometimes called
be graded. If we think of seeing or sight as a relational process ‘functionings’). Because functions are non-accidental, all of the
between an agent who is representing and the thing represented functions a given entity possesses are intimately tied to the type
and the accuracy of such representations ranging from 1 of entity under examination, whether the entity is biological or
(complete representational veracity) and 0 (no representational artifactual. Functions are internally-grounded realizable entities
veracity), blindness will be somewhere on the continuum from so changing the physical structure of its bearer may alter the
0 to 1 – the closer to 0 one's representation of stimulus, the realization of the function in question; and if the function
more blind that individual is. Given the above considerations, ceases to exist, the bearer must be changed physically [5].
one might draw the conclusion that there does not seem to be
an ontological category that corresponds to what blindness is as We think that sight is a BFO function of visual systems (or
an entity – blindness could be an amalgam of loosely related at least visual systems of creatures with higher-order cognitive
entities or something that is not itself ontologically well functions). One of the reasons we have for maintaining this
formed. While this conclusion is tempting, we do not find it to proposition is that sight appears to be a result of an
be satisfactory. evolutionary process and the various mechanisms of sight for
biological organisms straightforwardly seem the product of
Lending to the confusion surrounding the status of evolution. For non-biological entities possessing sight, if any,
blindness (and sight) is the method used for assessing visual the sight that they possess is not accidental, but rather a product
acuity. Typically, visual acuity is expressed as a relationship of design or intention on the part of the creator. This is
between two values – the distance a subject stands from an consistent with with the non-accidental nature of functions.
optical chart, and distance at which a normal subject would
stand from the chart to discern the same visual detail. Putting Another reason to think that sight is a function is that it is
aside the problems associated with this particular type of visual realized by processes grounded in a material entity. This is a
acuity assessment, we have discussed above how this can lead hallmark of a function as described above. Furthermore,
to confusion regarding what conditions are indicative of another reason that sight is a function lies in the fact that if
blindness [4]. sight ceases to exist, then the bearer is physically changed.
Although the entities still have the sight function, it is that they
It is useful for clinicians and researchers to have a coherent cannot realize that function due to some change in their
theory of blindness that encompasses the range of conditions physical constitution. Thus, there are many good reasons to
commonly understood to be forms of blindness. We support the assertion that sight is a function.
simultaneously realize that blindness seems to be characterized
as relative or context-sensitive (the term itself might be TABLE I. CURRENT ATTEMPTS TO CHARACTERIZE BLINDNESS
context-sensitive or the phenomenon might be context-
Ontology Term Definition Parent Class
The series of events required for an organism to receive a visual stimulus, convert Sensory
Gene Ontology (GO) Visual perception it to a molecular signal, and recognize and characterize the signal. Visual stimuli perception of
are detected in the form of photons and are processed to form an image. light stimulus
The series of events in which a visible light stimulus is received by a cell and
converted into a molecular signal. A visible light stimulus is electromagnetic
Detection of
GO Detection of visible light radiation that can be perceived visually by an organism; for organisms lacking a
light stimulus
visual system, this can be defined as light with a wavelength within the range 380
to 780 nm.
Detection of light stimulus
The series of events involved in visual perception in which a light stimulus is Visual
GO involved in visual
received and converted into a molecular signal. perception
perception
Determination of sensory The determination of the type or quality of a sensation. Sensory modalities Sensory
GO
modality include touch, thermal sensation, visual sensation, auditory sensation and pain. processing
Mammalian Abnormal
Blindness Loss of the sense of sight.
Phenotype (MP) vision
Abnormal eye
MP Abnormal vision Inability or decreased ability to see.
physiology
Abnormal
MP Decreased visual acuity Loss of visual acuity or ability to distinguish small details
visual acuity
Human Disease
Blindness N/A Retinal disease
Ontology (DO)
Color blindness A blindness that is characterized by the inability or decreased ability to see color,
DO Blindness
or perceive color differences, under normal lighting conditions.
Human Phenotype Blindness is the condition of lacking visual perception due to physiological or Visual
Blindness
(HP) neurological factors. Impairment
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ICBO 2014 Proceedings
Proceeding with the proposition that sight is a function, we within a few minutes. There are some extreme cases, however,
can characterize the specific type of function it is by where flash blindness will result in permanent vision loss [11].
identifying its defining features. Employing such a strategy, we
characterize sight as the function to receive photons and C. Current Solutions
interpret them as visual information. Relatedly, we can Given the above discussion, it seems that there should exist
characterize seeing as the process by which photons are the resources to represent blindness. One of the most likely
interpreted as visual information. Having given an account of candidate solutions involves using the Human Disease
sight as the realization of a function, it is then natural to Ontology (DO). DO currently does not provide a definition of
identify the process by which the sight function is realized as blindness but one plausible candidate posited on their behalf
vision. would follow their characterization of color blindness as an
inability or decreased ability to detect light stimulus. Color
An additional feature of functions (dispositions) and their blindness in DO is defined as: “a blindness that is characterized
functionings (realization processes) is that they are associated by the inability or decreased ability to see color, or perceive
with certain triggering processes under which they are realized. color differences, under normal lighting conditions.” [12]
The nature of this association is currently the subject of Moving from this definition of a specific type of blindness to
discussion in BFO but this much is clear: the relationship blindness generally should produce the result that blindness is
between the realization of a disposition and the disposition “the inability or decreased ability to see or perceive, under
itself is mediated by the trigger, and the triggering process is normal lighting conditions.”
connected to the realization process (perhaps causally) such
that the presence of the trigger and the disposition lead to the While an attractive view in general and one to which we are
realization of the disposition. For example, a sample of salt has mostly sympathetic, such a definition of blindness will not
a disposition to dissolve when placed in water. The realization stand up to careful examination. In the first place, DO
process would be the physical mechanism of the dissolving categorizes blindness as a disease. Blindness is not a disease.
process while the triggering process (or trigger) is the salt and Moreover, it is not a type of retinal disease as DO currently
water being together such that the process can manifest the characterizes it. Blindness may result from many diseases and
disposition to dissolve. Although there are few attempts to many diseases will complicate blindness and the sightedness of
formalize such entities as triggers, they are a commitment of individuals, but is not itself a disease. But it may also be the
BFO [6]. case that blindness does not result from a disease but rather a
single event, as is the case with flash blindness. It is also not
III. TWO INTERESTING CASES the case that blindness is limited to problems in the retina.
The reasons for thinking that sight is a function realized by Cortical blindness is a type of blindness that does not involve
a vision process in higher-order animals detailed in the last any malfunction with the retina. Even some specific types of
section provide our initial motivation. This section details two blindness are not limited to just one mechanism of realization
cases of blindness or types of blindness according to this in one location, as detailed in the last section.
account of sight. These rather easily remedied problems notwithstanding, the
A. Color Blindness more pressing concern is that there does not seem to be any
indication of what an inability or decreased ability would be.
Color blindness is a condition wherein an individual has an The concern is plain – abilities cannot lack according to BFO.
inability to distinguish between two or more colors. In some If abilities are dispositions or functions, then they are realizable
cases the two wavelengths of light are represented or entities. Realizable entities cannot present in degrees, as their
interpreted as the same when they are distinct. In other cases, existence is an all-or-nothing affair. If blindness is an inability
an individual cannot report a difference between two or more to detect light, then all cases of blindness will be a complete
wavelengths of photons [7]. The inability to distinguish inability to detect light stimulus, which fails to capture the
between two or more types of light is not limited to just one cases of blindness that are not the complete inability to detect
cone type [8]. Complicating this picture somewhat is that there light stimulus. If blindness is a decreased ability to detect light,
are many mechanisms identified as causes of color blindness then it cannot be represented as a decreased function or
and that these mechanisms are not localized to one anatomical disposition in BFO. But, since sight is a function, and blindness
region. Some color blindness is due to an individual lacking is the lack of sight, we are left to wonder whether an account of
cone cells or a certain type of cone cell. Other times the cause blindness can be given as an inability. We believe that this type
is cortical [9]. Thus, color blindness is similar to other types of of account is confused.
blindness in that the causes and mechanisms associated with it
are diverse and complex. Another route for capturing blindness is to maintain that
blindness is a disorder, where a disorder is “[a] material entity
B. Flash Blindness that is clinically abnormal and part of an extended organism.”
Flash blindness is a type of blindness that results from [13] The problem with this approach is that it is unclear that
exposure to sudden-onset bright light. The sudden light will blindness, as a phenomenon, is a material entity. If one thinks
oversaturate the photopigments of the retina and the individual that blindness is the absence of the sight function, then it does
will be unable to convert photons to a neural signal due to this not seem that blindness is a material entity (material entities are
oversaturation [10]. Flash blindness is commonly temporary not absences of functions). Further, one cannot point to a
blindness, where the subject regains their full ability to see material entity and identify it as blindness as blindness is not
spatially extended; but spatial extension is a hallmark of
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ICBO 2014 Proceedings
material entities. For these reasons, blindness cannot be a triggers and dispositions in formal ontology. This discussion is
disorder. a step toward providing an account of causality in BFO.
D. Proposed Solution The motivation of this project is to provide a simple yet
Drawing on the lessons from the previous sections we flexible ontological account of blindness. Since blindness is the
propose a solution to the problem that blindness poses for result of many ocular diseases, the construction of ontologies
ontology development. Because sight is a function and that incorporate both blindness and the diseases that result in
blindness is seemingly the non-realization of the function that blindness, either directly or indirectly, is of importance to the
is sight, we set forth an account of blindness where blindness is biomedical community. But this is not a purely classificatory
a reduction of the conditions under which the disposition that is exercise – the employment of the conditions under which a
the sight function is realized. To put it another way, the range disposition is realized (in this case a function) is a novel
of the triggering processes is narrowed such that the sight application of a tool that has been available for ontological
function is realized under a narrower range of conditions. developers for some time. It is the opinion of these authors that
this type of usage could yield further fruitful results.
This solution is able to deal with the cases outlined above.
For color blindness, we would say that color blindness is a ACKNOWLEDGMENTS
reduction in the (color) conditions under which a vision The authors would like to thank William Duncan and Isaac
function is realized. Although different types of color blindness Berger for their insights in commenting on this manuscript. We
will involve different types of reduction of conditions, they would also like to thank three anonymous reviewers for helpful
will be unified into a single phenomenon by the fact that they comments.
all involve the reduction of the light wavelengths that result in
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