Prevention of
Refractive Defects
of Vision
by Means of
Evolutionary
Medicine
Giacinto Libertini
www.r-site.org/ageing
www.programmed-aging.org
giacinto.libertini@tin.it
Preamble
What is Evolutionary
Medicine?
Evolutionary or Darwinian
Medicine [1-6] comes into
being in 1991 [1], but there
are
some
known
forerunners [7] (e.g. [8]) and
others not generally cited as
forerunners [9,10].
[1] Williams GC, Nesse RM (1991) The dawn of Darwinian medicine. Quart. Rev. Biol. 66, 1-22.
[2] Nesse RM, Williams GC (1994) Why we get sick. New York (USA), Times Books.
[3] Stearns SC (ed) (1999) Evolution in health and disease (1st ed.). Oxford (UK), Oxford University Press.
[4] Trevathan WR, Smith EO, McKenna JJ (eds) (1999) Evolutionary Medicine. New York (USA), Oxford
University Press.
[5] Trevathan WR, Smith EO, McKenna JJ (eds) (2008) Evolutionary Medicine: new perspectives. New York
(USA), Oxford University Press.
[6] Stearns SC, Koella JC (eds) (2008) Evolution in health and disease (2nd ed.). Oxford (UK), Oxford
University Press.
[7] Trevathan WR, Smith EO, McKenna JJ (2008) Introduction and overview of Evolutionary Medicine. In:
Trevathan WR, Smith EO, McKenna JJ (eds) Evolutionary Medicine: new perspectives. New York (USA),
Oxford University Press.
[8] Eaton SB, Shostak M, Konner M (1988) The paleolithic prescription: a program of diet & exercise and a
design for living. New York (USA), Harper & Row.
[9] Price WA (1939) Nutrition and Physical Degeneration. New York – London, Paul B. Hoeber.
[10] Libertini G (1983) Ragionamenti Evoluzionistici. Naples (Italy), Società Editrice Napoletana; English
Edition (2011): Evolutionary Arguments. Crownsville (USA), Azinet Press.
Evolutionary Medicine is not an
Alternative Medicine
(like homeopathy, iridology, ayurvedic
medicine, naturopathy, traditional
Chinese medicine, energy medicine, etc.)
but a Medicine that is
more thoroughly scientific
in that it involves the concepts of
Evolutionism.
A medicine that ignored the principles of
chemistry, for example, would be partially
scientific.
Similarly, a medicine that ignores
the principles of evolution
is partially scientific.
So, the contrast is not between:
Current Medicine
Alternative Medicines
but between:
Current Medicine
(which in most cases
ignores Evolutionism)
Evolutionary Medicine
(which is a more thoroughly
scientific medicine)
However, the first practical question is immediate:
Is this difference only a theoretical / verbal nicety?
or
Does this difference have strong and significant implications
for the structure of medical studies and for health organization?
Evolutionary Medicine involves
applicative consequences.
many
concepts and
Here, I develop a practical application of a simple concept,
the “mismatch” [1,2], to the genesis of refractive defects of
vision.
The concept of “mismatch” is simple but with huge
implications:
If a species is adapted to a certain range of
conditions (including diet, environmental
conditions, interrelations with other living
beings, etc.), called for brevity “ecological
niche”, any change in the ecological niche
potentially is a source of disfunctions (diseases),
because there is no adaptation to the new
conditions.
This is defined as "mismatch”.
[1] Eaton SB, Shostak M, Konner M (1988) The paleolithic prescription: a program of diet & exercise and
a design for living. New York (USA), Harper & Row.
[2] Libertini G (2009) Prospects of a Longer Life Span beyond the Beneficial Effects of a Healthy
Lifestyle, in: Bentely JV, Keller MA (eds) Handbook on Longevity: Genetics, Diet & Disease, New York
(USA), Nova Science Publishers Inc.
Refractive Defects of Vision
in the Context of Evolutionary Medicine
Step 1 - Epidemiological study
of modern populations
Refractive defects (myopia, astigmatism and hyperopia) are a
group of related diseases with frequency:
- very common [1-3]
- varying greatly from population to population (e.g.: “The
prevalence of myopia in Asia is as high as 70-90%, in Europe and
America 30-40%, and in Africa 10-20 %” [1])
…
[1] Fredrick DR (2002) Myopia. BMJ. 324, 1195-9.
[2] Dirani M et al. (2010) Prevalence of refractive error in Singaporean Chinese children: the strabismus,
amblyopia, and refractive error in young Singaporean Children (STARS) study. Invest. Ophthalmol. Vis.
Sci. 51, 1348-55.
[3] Chow YC, Dhillon B, Chew PT, Chew SJ (1990) Refractive errors in Singapore medical students.
Singapore Med. J. 31, 472–3.
Step 1 - (CONTINUED)
…
- varying greatly within the same population with changing conditions [1-3]
- varying greatly within a population over a short time [2,4,5] (see Figure)
[1] Rose KA , Morgan IG, Smith W, Burlutsky G,
Mitchell P, Saw S-M (2008) Myopia, lifestyle,
and schooling in students of Chinese ethnicity
in Singapore and Sydney. Arch. Ophthalmol.
126, 527-30.
[2] Cordain, L, Eaton, SB, Miller, JB, Lindeberg,
S, Jensen, C (2002) An evolutionary analysis
of the aetiology and pathogenesis of juvenileonset myopia. Acta Ophthalmol. Scand. 80,
125–35.
[3] Garner LF, Owens H, Kinnear RF, Frith MJ.
(1999) Prevalence of myopia in Sherpa and
Tibetan children in Nepal. Optom. Vis. Sci. 76,
282-5.
[4] Edwards MH, Lam CS (2004). The
epidemiology of myopia in Hong Kong. Ann.
Acad. Med. Singapore. 33, 34-8.
[5] Morgan, RW, Munro, M (1973) Refractive
problems in northern natives. Can. J.
Ophthalmol. 8,: 226–8.
(From [2]:) Figure 1. Moderate myopia (1.00–5.00 D)
by age in Indians and Eskimos of the Yukon and
NorthWest territories. Adapted from Morgan &
Munro (1973) ([5])
Step 2 - Comparison between the frequency of a disease in modern
populations and the frequency of the same disease in populations
in primitive conditions
The study of primitive peoples shows that these defects are very rare or nonexistent among
them.
As regards Australian Aborigenes: “The marvelous vision of these primitive people is
illustrated by the fact that they can see many stars that our race cannot see. In this
connection it is authoritatively recorded regarding the Maori of New Zealand that they can
see the satellites of Jupiter which are only visible to the white man's eye with the aid of
telescopes. These people prove that they can see the satellites by telling the man at the
telescope when the eclipse of one of the stars occurs. It is said of these primitive Aborigines
of Australia that they can see animals moving at a distance of a mile which ordinary white
people can not see at all.” [1]
As regards Yakuts (a Siberian people): “Many travelers observed what some of them call
‘telescopic’ eyesight among these peoples. A Yakut distinguished with the naked eye stars in
the Pleiades not usually seen without a telescope. The Yakuts say there are many stars in
this group, but only seven large ones” [2]
…
[1] Price, WA (1939) Nutrition and Physical Degeneration. New York – London, Paul B. Hoeber.
[2] De Hutorowicz H, Adler BF (1911) Maps of Primitive Peoples. Bull. Amer. Geogr. Soc. 43, 669-79.
Step 2 - (CONTINUED)
As regards two hunter-gatherer populations: “Using a retinoscope and cycloplegia, Holm
(1937) refracted 2364 members (aged 20–65 years) of several hunter-gatherer tribes in
Gabon (formerly French Equatorial Africa) in 1936. Of the 3624 eyes examined, only 14
were classified as myopic (nine eyes from − 0.50 to 1.00 D; five eyes from − 3.00 to − 9.00 D),
thereby yielding a myopia incidence rate of 0.4%. Similar low rates for myopia were
reported by Skeller (1954), who refracted the eyes of 775 Angmagssalik Eskimos as part of a
comprehensive anthropological study carried out in 1954. Retinoscopy in conjunction with
cycloplegia demonstrated that of the 1123 eyes examined, only 13 (1.2%) were classified as
myopic (nine eyes =− 1.00 D; four eyes =− 1.25 D).” [1]
“a number of lines of evidence strongly reject the notion that [a] recent (in evolutionary
terms) relaxation of natural selection pressures could be responsible for the high incidence
of myopia in modern, technological societies.” [1]
Data from Step 1 and Step 2 indicate that refractive defects are surely a group of diseases
caused by environmental factors, i.e. by presumable mismatch phenomena.
[1] Cordain, L, Eaton, SB, Miller, JB, Lindeberg, S, Jensen, C (2002) An evolutionary analysis of the
aetiology and pathogenesis of juvenile-onset myopia. Acta Ophthalmol. Scand. 80, 125–35.
Step 3 - Hypotheses on the possible changes in the ecological niche
underlying the disease and on possible pathogenetical mechanisms
Excessive near work, especially using artificial lighting, an improbable condition in the
ecological niche to which we are adapted, is a common hypothesis regarding the causes of
refractive defects, in particular myopia [1,2].
Against this hypothesis: “In an earlier study of 977 school children (6–17 years of age) on
the remote South Pacific island of Vanuatu, Garner et al. (1985) found that only 1.3% of
subjects had myopia greater than − 0.25 D, despite engaging in about 8 hrs of school work
per day.” [3]
Another hypothesis ascribes the epidemic of myopia incidence to dietary alterations, in
particular the “increase in high glycaemicload foods” [3]. But, in two homogeneous
populations with no detectable difference in dietary habits, incidence of myopia was very
different [4].
…
[1] Zylbermann R, Landau D, Berson D (1993): The influence of study habits on myopia in Jewish
teenagers. J. Pediatr. Ophthalmol. Strabismus 30, 319–22.
[2] McBrien NA, Adams DW (1997): A longitudinal investigation of adult-onset and adult-progression of
myopia in an occupational group. Refractive and biometric findings. Invest Ophthalmol. 38, 321–33.
[3] Cordain L, Eaton SB, Miller JB, Lindeberg S, Jensen C (2002) An evolutionary analysis of the
aetiology and pathogenesis of juvenile-onset myopia. Acta Ophthalmol. Scand. 80, 125–35.
[4] Rose KA , Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw S-M (2008) Myopia, lifestyle, and
schooling in students of Chinese ethnicity in Singapore and Sydney. Arch. Ophthalmol. 126, 527-30.
Step 3 – (CONTINUED)
A study was made of two homogeneous groups of 6-7-years old children of Chinese
ethnicity, living in Singapore and in Sidney, respectively, with the same frequency of
myopia in their parents: “Children in Sidney read more books per week (P < .001) and did
more near-work activity (P = .002). Children in Sidney spent more time on outdoor
activities (13.75 vs 3.05 hours per week) (P < .001)”. The prevalence of myopia was 3.3%
in Sidney and 29.1% in Singapore [1].
This suggests that the critical factor is the outdoor activity, alias the exposition to natural
light, a hypothesis confirmed by other studies [2,3].
In particular “Higher levels of total time spent outdoors, rather than sport per se, were
associated with less myopia” [2].
In these studies, near-work activities appeared to be an independent aggravating factor,
but not the main cause of myopia [2,3].
[1] Rose KA, Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw SM (2008) Myopia, lifestyle, and
schooling in students of Chinese ethnicity in Singapore and Sydney. Arch. Ophthalmol. 126, 527-30.
[2] Rose KA, Morgan IG, Ip J, Kifley A, Huynh S, Smith W, Mitchell P. (2008) Outdoor activity
reduces the prevalence of myopia in children. Ophthalmol. 115, 1279-85.
[3] Dirani M, Tong L, Gazzard G, Zhang X, Chia A, Young TL, Rose KA, Mitchell P, Saw SM. (2009)
Outdoor activity and myopia in Singapore teenage children. Br. J. Ophthalmol. 93, 997-1000.
Step 4 - Study of the mechanisms linking alterations
of the ecological niche to the pathogenesis of the disease
It is known – from experiments on chickens - that the application (for 7 days, beginning at 5
days of age), of spherical defocus lenses or of translucent occluders to one eye, or exposure to
constant light, cause astigmatism associated with myopia or hyperopia.
In control birds, astigmatism is normal at birth and disappears, or decreases, over the
following days [1].
Similar results were obtained in monkeys [2].
In our species too, astigmatism is normal at the birth and disappears in the first years of life:
“Infants have a high incidence of clinically significant astigmatism.” “Of 28 children who
had large amounts of astigmatism in the first year, all showed elimination or a large
reduction in the amount of the cylindrical error by 4 years” [3]
“Full term newborn babies are known to be on average hypermetropic at birth. Preterm
babies tend to be myopic when examined at an age corresponding to term …” [4]
[1] Kee CS, Deng L (2008) Astigmatism associated with experimentally induced myopia or hyperopia in
chickens. Invest. Ophthalmol. Vis. Sci. 49, 858-67.
[2] Kee CS, Hung LF, Qiao-Grider Y, Ramamirtham R, Smith EL 3rd. (2005) Astigmatism in monkeys
with experimentally induced myopia or hyperopia. Optom. Vis. Sci. 82, 248-60.
[3] Gwiazda J, Scheiman M, Mohindra I, Held R (1984. Astigmatism in children: changes in axis and
amount from birth to six years. Invest Ophthalmol Vis Sci. 25, 88-92.
[4] Varghese RM, Sreenivas V, Mammen Puliye J, Varughese S (2009). Refractive Status at Birth: Its
Relation to Newborn Physical Parameters at Birth and Gestational Age. PLoS ONE 4(2): e4469.
Step 4 – (CONTINUED)
Thus, at birth, the eye is imperfect. The image is focused either too far forward or too far
behind the retina. There is also a deformation of the image on one plane versus the other
(astigmatism).
The genetic program of eye development means that, at birth, an eye will have only
approximate vision. Immediately after birth, it is activated another program that modulates
the further development of the eye in order to achieve optimum vision.
Step 4 – (CONTINUED)
In other words, these data indicate that, at birth, the eye is hyperopic (a little too short) or
myopic (a little too long) and astigmatic (different curvature on the vertical vs the horizontal
plane). In the first period of life, by means of neurological and morphogenetic mechanisms,
the length and the curvatures of the eye are adapted to obtain the achieve the best possible
vision (“emmetropization”).
It is like a camera with a very sophisticated autofocus capacity in its rest position (remote
viewing): when it comes out of the factory, it is not focused, but it achieves, by itself, an
optimal hardware focusing for remote viewing IF WE RESPECT THE
MANUFACTURER’S INSTRUCTIONS (e.g.: do NOT point the camera at anything which
is too dark or too bright!).
Well, our eye / camera has a hardware
focusing capacity only in the first period of
life, and it is essential that the conditions
are similar to the those to which our species
is adapted. In different conditions, proper
functioning is not guaranteed and
malfunction is probable!
Step 5 – Possible restoration of the normal, i.e. primeval, conditions
or possible compensatory conditions
Under modern conditions of life, particularly in urban areas with high population densities,
it is "normal" that babies do not grow up outdoors, with exposure to natural light.
It is a widespread belief that babies should be protected as much as possible from the
external environment, in particular from direct exposure to sunlight, as this will damage
them in some way.
Many infants spend their first months of life almost exclusively indoors, only exposed to
artificial lighting, with uneven and weak brightness, and, in all cases, under conditions quite
different from those to which our species is adapted.
For proper eye development, babies
should be exposed as much as possible
to natural light conditions; sunlight
should not be avoided and conditions
should be as similar as possible to the
original ones.
Step 6 - Analysis of the results achieved and ideation
and proposal of further improvements
Such measures should be applied on a large scale, because evidence indicates that the current
epidemic of refractive defects is caused by alterations in the exposure rate to natural light in
infants and children.
Selected groups of infants and children, growing up under various conditions of compliance
with these guidelines, should be carefully monitored from an ophthalmologic point of view
and compared with control groups that fail to comply with them.
It would be essential to know how much the exposure to natural light is needed to prevent the
occurrence of refractive defects.
First Objection
Before applying these measures of prevention on a large scale,
observation of controlled groups in order to confirm their validity
is necessary.
But this objection would be generated by a contradiction of current Medicine.
In fact, when a new drug is proposed, we rightly expect a series of experiments, in several
stages, before its use is authorized. Meanwhile, the NON-use of the drug is considered to be
due and NOT subject to preventive experimentation.
On the contrary, in the case of a new habit of life, alias a change of the ecological niche, the
new habit is introduced and accepted WITHOUT any trial that demonstrates its safety.
Now, If a new NOT tested habit of life is suspected of causing illness, the indication to stop
this habit of life is rightful and proper.
Why, before its suspension, should we demonstrate its harmfulness and the benefits
resulting from its suspension?
Such an absurd principle has been used for decades to extend the use of smoke without that
smokers were at least warned of the deadly risks they were running. Again, a new habit
(smoking) was introduced without any evidence that proved its safety and for decades it was
claimed that its harm should be proved before taking action against it.
After many
scientific tests
(while the slaughter
continued)
Any change of the ecological
niche to which a species is
adapted must be considered
potentially harmful until the
contrary is proved.
In the case of a new drug, this
principle is observed!
[Precautionary principle]
But for other modifications of
the ecological niche, no
precaution is taken.
It is presumed – irrationally
and stupidly, because of nonscientific evaluations – that a
modification must not be
considered harmful until the
experience
proves
the
contrary!
[Imprudence Principle]
The correct scientific logic would be to take steps against a change in the
ecological niche on the sole grounds of the suspicion that this change is
bad and BEFORE the sure demonstration in irreproachable scientific
terms.
Afterwards, the results in populations (or fractions of populations), which pursue - to a
greater or lesser extent - the restoration of more physiological (alias natural) conditions
must be compared both to confirm the expected results and for evaluating other possible
measures.
But one should not expect the results of test samples before applying the aforesaid
preventive actions on a large scale.
For refractive defects the case is analogous.
It is not acceptable to wait decades of experimentation to prove that the restoration of
conditions closer to the natural ones can dramatically reduce the incidence of refractive
disorders.
Measures of increased exposure to natural light conditions from the newborn age must be
propagandized and applied on a large scale.
Afterwards, the results in populations, and fractions of populations, which apply to a
greater or lesser extent the restoration of more physiological, alias natural, conditions must
be compared both to confirm the expected results and for evaluating the necessary degree of
exposure to natural light for optimal results.
But one should not expect the results of test samples before applying the aforesaid
preventive actions on a large scale.
Second Objection
The refractive defects should be attributed to the combination
of environmental and genetic factors.
This is a misleading way of describing the case.
Certainly, when an individual is exposed to an ecological niche to which its genes are not
adapted, in the diseases that are caused by the altered ecological niche, his genes, which are
more or less resistant to the onset of diseases, come into play.
But, we cannot and should not consider the genes that are less resistant to the diseases as
pathological: they are entirely normal genes that in new conditions, to which the species is
not adapted, have responses that are more or less effective against the onset of pathological
changes.
For example, our species is certainly not adapted to smoking.
If, in smokers, some suffer respiratory failure, others chronic bronchitis and others cancer,
it is not correct to say that those who develop these diseases have bad genes that somehow
must be corrected, or for which it is necessary to develop opportune treatments.
The logic says that we must avoid the alteration of the ecological niche and thus prevent the
development of diseases that result from it.
It should be noted that in some cases refractive defects are actually due to a genetic
alteration. In these cases any preventive measure is not able to prevent the disease. But, if we
refer to data from the study of populations living under primitive conditions, the incidence
of such cases is less than 1%. Therefore, the attribution of responsibility to genetic factors
should not be an excuse to diminish or avoid to address the most attention and efforts on
prevention.
Conclusion
Refractive defects involve significant costs arising from the adoption of artificial means to
correct refraction (lenses, contact lenses, lenses inserted artificially, laser surgery or other
methods).
In cases where the defects are of high grade, there are complications that involve additional
costs, worsening vision and often involve the loss of sight.
Even in cases where there is no loss of sight, artificial means of correction only partially
remedy the defect and are a source of limitation or disability for many activities.
Overall, refractive defects involve significant costs and reduced quality of life.
Current Medicine is directed to pursue means of correction that are increasingly
sophisticated and refined.
But the best goal would certainly be to minimize new cases of refractive defects, reserving
the cures to exceptional cases.
This would limit the degradation of quality of life, a lot of suffering, and - last but something
to be reckoned with - rising costs.
This is possible with the correct application of trivial principles of Evolutionary Medicine.
…
Conclusion - (CONTINUED)
Modern doctors, largely unaware even of the
most basic principles of Evolutionism, do not
know these possibilities.
At the same time, evolutionary biologists are
unaware of the extreme importance of these
possibilities for a rational organization of a
health system that should primarily prevent
diseases.
It is therefore essential the integration of the
knowledge of Evolutionism into the active
body of current Medicine, transforming it
into Evolutionary Medicine.
Thanks
for your attention
This presentation is on my personal pages too:
www.r-site.org/ageing
(e-mail: giacinto.libertini@tin.it)