To confirm the prediction of emmetropization feedback theory that myopia can be prevented by corr... more To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic. We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16. Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values. The treatment of the twins with partial correction of their hyperopia was successful. Prevention of myopia with this technique is relatively simple and powerful. The use of this myopia prevention treatment has no adverse effects. This prevention treatment is indicated in children with a hyperopic reserve at risk of developing myopia.
Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie, Jan 9, 2015
The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st ... more The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st and 2nd generation correlations, relevant to whether myopia is random or inherited. First- and second-generation ocular refraction data are assembled from N = 34 families, average of 2.8 children per family. From this group, data are available from N = 165 subjects. Inter-generation regressions are performed on all the data sets, including correlation coefficient r, and myopia prevalence [%]. Prevalence of myopia is [M] = 38.5 %. Prevalence of high myopes with |R| >6 D is [M-] = 20.5 %. Average refraction is <R> = -1.84 D ± 3.22 (N = 165). For the high myopes, |R| >6 D, prevalence for the parents is [M-] = 25 %, for the 2nd generation [M-] = 16.5 %. Average myopia level for the high myopes, both generations, is <S> = -7.52 D ± 1.31 D (N = 33). Regression parameters are calculated for all the data sets, yielding correlation coefficients in the range r = 0.48-0.72 for som...
Progressive myopia in humans and lid-sutured myopia in primates have been considered to be differ... more Progressive myopia in humans and lid-sutured myopia in primates have been considered to be different processes. This report seeks to establish the connection between progressive myopia in humans and lid suture myopia in macaque monkeys. We followed the axial length of 4 lid-sutured macaque monkeys over an 18 month period. Their axial length is directly related to myopia. We also studied the myopia progression in corrected human subjects. Macaques and humans exhibit a linear time course of myopia progression when lid-sutured or corrected with lenses, respectively. A linear progression is observed in lid-sutured eyes of four macaques, r = 0.94, p < 0.05. Human progressive myopia and lid-suture myopia can be modeled by the same feedback process. In both cases the functional equivalent is the opening of the feedback loop. The open loop feedback process predicts a linear progression of myopia. This prediction was confirmed in human subjects and it is now confirmed in our macaque subje...
This study examined differences in self-concept between children with congenital low vision and t... more This study examined differences in self-concept between children with congenital low vision and their sighted peers. The sample consisted of thirty-four eight- to eleven-year-old children, seventeen with congenital low vision (nine boys and eight girls) and seventeen who were sighted. The findings revealed that the children with low vision scored lower than those with normal vision in aspects of their
Bacterial viability in bacterial adherence to new soft contact lenses (SCLs) was studied by expos... more Bacterial viability in bacterial adherence to new soft contact lenses (SCLs) was studied by exposing polymacon and lidofilcon A lenses to Pseudomonas aeruginosa: L, live, untreated bacteria; H, bacteria heated for 1 h at 100 degrees C; and P, bacteria treated with 3% hydrogen peroxide for 1 h. Cultures of groups L, H, and P showed heavy, no, and minimal bacterial growth, respectively. Scanning electron microscopy (SEM) showed significantly less bacteria on new SCLs in groups H and P. Transmission electron microscopy (TEM) showed that bacterial shape was mostly preserved in all groups, with marked intracellular and cell membrane changes and breaks (groups H and P), margination of intracellular electron-dense material (group H), and central and peripheral vacuolation (group P). Adherence to new SCLs appears to be an active process, as killed or altered bacteria adhere less.
Medina, A. Nature Eye (16 June 2017) | doi:10.1038/eye.2017.123
ABSTRACT
Purpose and Background
... more Medina, A. Nature Eye (16 June 2017) | doi:10.1038/eye.2017.123
ABSTRACT Purpose and Background The eyeball and, in particular, the cornea deform in vitro by the application of a distending force like other visco-elastic tissue. If the force is large enough, the cornea strains beyond the elastic range, and a permanent deformation occurs. Such permanent strain is referred to as "plastic" strain. The phenomenon, however, has never been observed or produced on living tissue. This report seeks to demonstrate that the central radius of a patient’s cornea can be altered in a controlled manner designed to correct refractive errors. Methods To plastically deform the living cornea, we applied a vacuum to the cornea of eight rabbits and five human eyes with a novel device. This device consists of a chamber of 11 mm in diameter. The chamber is radially divided into four interconnected sub-chambers. Results Here we show that a strain can be achieved in vivo with a force produced by the application of the specially designed chamber where air is evacuated. An anatomical modification of the cornea of humans and rabbits was achieved. The deformation of the cornea was plastic, and therefore permanent. Conclusions The method described here -Pneumatic Keratology- can be used to alter the cornea by non-invasive means. A vacuum chamber with radial openings alters the collagen fibers in the stroma and flattens the cornea. A flatter cornea corrects or reduces myopia.
Purpose
To confirm the prediction of emmetropization feedback theory that myopia can
be prevented... more Purpose To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic. Methods We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16. Results Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values. Conclusions The treatment of the twins with partial correction of their hyperopia was successful. Prevention of myopia with this technique is relatively simple and powerful. The use of this myopia prevention treatment has no adverse effects. This prevention treatment is indicated in children with a hyperopic reserve at risk of developing myopia. See link for full paper.
The mystery of emmetropization, that strange force
squeezing the frequency distribution of the to... more The mystery of emmetropization, that strange force squeezing the frequency distribution of the total refractive errors into its sharply peaked shape has been up-to-date unsolved. Let alone the cause of ametropia. After analysing refraction with age in any subject it is clear that a servo mechanism exists and furthermore it can be measured. This servo can explain theoretically all kind of ametropias, the effect of glasses and the eye refraction of any subject from intrauterine life. Experiments already conducted support the theory, and the results show that they are in perfect agreement. From a practical point of view, both theoretical and experimental considerations would allow us to treat ametropic patients in order to reduce their dioptric value.
The response of a second-order feedback system is used to describe the control ling process that... more The response of a second-order feedback system is used to describe the control ling process that regulates the refraction of the human eye to achieve optimal visual acuity over the years (emmetropization). From data collected in past refractions, the equation of the feedback system has been derived for individual eyes and used to predict changes in their refraction with age with an accuracy of 0.50 diopters for 89 .1% of the eyes tested. If the model is applied to other populations, the root mean square error of prediction will be between 0.20 and 0.36 diopters with a 95% degree of confidence. The model indicates that corrective lenses applied to the eyes, especially in the early years of life, will cheat the servo system and defeat the emmetropization process.
A mechanism called emmetropization appears to control the ocular focus over the years. Emmetropiz... more A mechanism called emmetropization appears to control the ocular focus over the years. Emmetropization could regulate the refractive media (dimensions of cornea, lens, and axial length), detecting the focus or refractive error of the eye at rest and initiating changes to reduce the refractive error; this concept suggests that a feedback loop is operational. A feedback mechanism for ocular refraction implies that correcting ametropia with lenses initiates a change in the refractive state of the eye. The long-term effect of corrective lenses on ocular refraction is investigated with a mathematical feedback model that can predict the extent and direction of this change. The results indicate that lenses worsen existing ametropia conditions. However, the use of appropriate lenses in early life can reduce and correct developing ametropia.
Vision Res. Vol. 33, No. 1, pp. 21-26. 1993
The existence of a regulatory mechanism that control... more Vision Res. Vol. 33, No. 1, pp. 21-26. 1993 The existence of a regulatory mechanism that controls the growth of the eye toward emmetropia is generally agreed upon, but such an emmetropization mechanism has never been verified experimentally. This report supports the hypothesis that emmetropization can be described as a feedback process with a first-order equation and establishes a theoretical framework for future study, experimentation, and manipulation of this elusive mechanism. The feedback hypothesis has been tested by comparing two models. The first is a first-order feedback system, the second a non-feedback model with an almost identical equation. The feedback model fits data from human subjects significantly better.
Objective: Progressive myopia in humans and lid-sutured myopia in primates have been considered t... more Objective: Progressive myopia in humans and lid-sutured myopia in primates have been considered to be different processes. This report seeks to establish the connection between progressive myopia in humans and lid suture myopia in macaque monkeys. Methods: We followed the axial length of 4 lid-sutured macaque monkeys over an 18 month period. Their axial length is directly related to myopia. We also studied the myopia progression in corrected human subjects. Macaques and humans exhibit a linear time course of myopia progression when lid-sutured or corrected with lenses, respectively. Results: A linear progression is observed in lid-sutured eyes of four macaques, r = 0.94, p < 0.05. Human progressive myopia and lid-suture myopia can be modeled by the same feedback process. In both cases the functional equivalent is the opening of the feedback loop. Conclusions: The open loop feedback process predicts a linear progression of myopia. This prediction was confirmed in human subjects and it is now confirmed in our macaque subjects. This process also explains the very rapid rate of myopia progression of lid sutured eyes. Journal of Nature and Science, 1(6):e121, 2015 Emmetropia | emmetropization | myopia | Laplace transform | feedback | ultrasound Nomenclature r = correlation coefficient p = significance level d = diopters t = time [years] s = complex variable in the Laplace or s domain k = emmetropization system time constant [years] R = uncorrected refractive error [d] A = initial refraction at birth [d] F(s) = emmetropization transfer function o(t) = system output or response [d] G(s) = forward or open loop transfer function i(t) = input to the feedback system [d] O(s) = output function in the Laplace or s domain L{ } = Laplace transform L-1 { } = inverse Laplace transform (A/k)t = open loop response function to step A input R/k = ramp slope or myopia progression rate, human [d/year] A/k = ramp slope or myopia progression rate, macaque [d/year]
To confirm the prediction of emmetropization feedback theory that myopia can be prevented by corr... more To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic. We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16. Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values. The treatment of the twins with partial correction of their hyperopia was successful. Prevention of myopia with this technique is relatively simple and powerful. The use of this myopia prevention treatment has no adverse effects. This prevention treatment is indicated in children with a hyperopic reserve at risk of developing myopia.
Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie, Jan 9, 2015
The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st ... more The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st and 2nd generation correlations, relevant to whether myopia is random or inherited. First- and second-generation ocular refraction data are assembled from N = 34 families, average of 2.8 children per family. From this group, data are available from N = 165 subjects. Inter-generation regressions are performed on all the data sets, including correlation coefficient r, and myopia prevalence [%]. Prevalence of myopia is [M] = 38.5 %. Prevalence of high myopes with |R| >6 D is [M-] = 20.5 %. Average refraction is <R> = -1.84 D ± 3.22 (N = 165). For the high myopes, |R| >6 D, prevalence for the parents is [M-] = 25 %, for the 2nd generation [M-] = 16.5 %. Average myopia level for the high myopes, both generations, is <S> = -7.52 D ± 1.31 D (N = 33). Regression parameters are calculated for all the data sets, yielding correlation coefficients in the range r = 0.48-0.72 for som...
Progressive myopia in humans and lid-sutured myopia in primates have been considered to be differ... more Progressive myopia in humans and lid-sutured myopia in primates have been considered to be different processes. This report seeks to establish the connection between progressive myopia in humans and lid suture myopia in macaque monkeys. We followed the axial length of 4 lid-sutured macaque monkeys over an 18 month period. Their axial length is directly related to myopia. We also studied the myopia progression in corrected human subjects. Macaques and humans exhibit a linear time course of myopia progression when lid-sutured or corrected with lenses, respectively. A linear progression is observed in lid-sutured eyes of four macaques, r = 0.94, p < 0.05. Human progressive myopia and lid-suture myopia can be modeled by the same feedback process. In both cases the functional equivalent is the opening of the feedback loop. The open loop feedback process predicts a linear progression of myopia. This prediction was confirmed in human subjects and it is now confirmed in our macaque subje...
This study examined differences in self-concept between children with congenital low vision and t... more This study examined differences in self-concept between children with congenital low vision and their sighted peers. The sample consisted of thirty-four eight- to eleven-year-old children, seventeen with congenital low vision (nine boys and eight girls) and seventeen who were sighted. The findings revealed that the children with low vision scored lower than those with normal vision in aspects of their
Bacterial viability in bacterial adherence to new soft contact lenses (SCLs) was studied by expos... more Bacterial viability in bacterial adherence to new soft contact lenses (SCLs) was studied by exposing polymacon and lidofilcon A lenses to Pseudomonas aeruginosa: L, live, untreated bacteria; H, bacteria heated for 1 h at 100 degrees C; and P, bacteria treated with 3% hydrogen peroxide for 1 h. Cultures of groups L, H, and P showed heavy, no, and minimal bacterial growth, respectively. Scanning electron microscopy (SEM) showed significantly less bacteria on new SCLs in groups H and P. Transmission electron microscopy (TEM) showed that bacterial shape was mostly preserved in all groups, with marked intracellular and cell membrane changes and breaks (groups H and P), margination of intracellular electron-dense material (group H), and central and peripheral vacuolation (group P). Adherence to new SCLs appears to be an active process, as killed or altered bacteria adhere less.
Medina, A. Nature Eye (16 June 2017) | doi:10.1038/eye.2017.123
ABSTRACT
Purpose and Background
... more Medina, A. Nature Eye (16 June 2017) | doi:10.1038/eye.2017.123
ABSTRACT Purpose and Background The eyeball and, in particular, the cornea deform in vitro by the application of a distending force like other visco-elastic tissue. If the force is large enough, the cornea strains beyond the elastic range, and a permanent deformation occurs. Such permanent strain is referred to as "plastic" strain. The phenomenon, however, has never been observed or produced on living tissue. This report seeks to demonstrate that the central radius of a patient’s cornea can be altered in a controlled manner designed to correct refractive errors. Methods To plastically deform the living cornea, we applied a vacuum to the cornea of eight rabbits and five human eyes with a novel device. This device consists of a chamber of 11 mm in diameter. The chamber is radially divided into four interconnected sub-chambers. Results Here we show that a strain can be achieved in vivo with a force produced by the application of the specially designed chamber where air is evacuated. An anatomical modification of the cornea of humans and rabbits was achieved. The deformation of the cornea was plastic, and therefore permanent. Conclusions The method described here -Pneumatic Keratology- can be used to alter the cornea by non-invasive means. A vacuum chamber with radial openings alters the collagen fibers in the stroma and flattens the cornea. A flatter cornea corrects or reduces myopia.
Purpose
To confirm the prediction of emmetropization feedback theory that myopia can
be prevented... more Purpose To confirm the prediction of emmetropization feedback theory that myopia can be prevented by correcting the hyperopia of a child at risk of becoming myopic. Methods We conducted such myopia prevention treatment with twins at risk. Their hyperopia was partially corrected by one half at age 7 and in subsequent years until age 16. Results Hyperopia progressively decreased in all eyes as expected. None of the twins developed myopia. The spherical equivalent refractions of the followed eyes were +1 and +1.25 D at age 16. Feedback theory accurately predicted these values. Conclusions The treatment of the twins with partial correction of their hyperopia was successful. Prevention of myopia with this technique is relatively simple and powerful. The use of this myopia prevention treatment has no adverse effects. This prevention treatment is indicated in children with a hyperopic reserve at risk of developing myopia. See link for full paper.
The mystery of emmetropization, that strange force
squeezing the frequency distribution of the to... more The mystery of emmetropization, that strange force squeezing the frequency distribution of the total refractive errors into its sharply peaked shape has been up-to-date unsolved. Let alone the cause of ametropia. After analysing refraction with age in any subject it is clear that a servo mechanism exists and furthermore it can be measured. This servo can explain theoretically all kind of ametropias, the effect of glasses and the eye refraction of any subject from intrauterine life. Experiments already conducted support the theory, and the results show that they are in perfect agreement. From a practical point of view, both theoretical and experimental considerations would allow us to treat ametropic patients in order to reduce their dioptric value.
The response of a second-order feedback system is used to describe the control ling process that... more The response of a second-order feedback system is used to describe the control ling process that regulates the refraction of the human eye to achieve optimal visual acuity over the years (emmetropization). From data collected in past refractions, the equation of the feedback system has been derived for individual eyes and used to predict changes in their refraction with age with an accuracy of 0.50 diopters for 89 .1% of the eyes tested. If the model is applied to other populations, the root mean square error of prediction will be between 0.20 and 0.36 diopters with a 95% degree of confidence. The model indicates that corrective lenses applied to the eyes, especially in the early years of life, will cheat the servo system and defeat the emmetropization process.
A mechanism called emmetropization appears to control the ocular focus over the years. Emmetropiz... more A mechanism called emmetropization appears to control the ocular focus over the years. Emmetropization could regulate the refractive media (dimensions of cornea, lens, and axial length), detecting the focus or refractive error of the eye at rest and initiating changes to reduce the refractive error; this concept suggests that a feedback loop is operational. A feedback mechanism for ocular refraction implies that correcting ametropia with lenses initiates a change in the refractive state of the eye. The long-term effect of corrective lenses on ocular refraction is investigated with a mathematical feedback model that can predict the extent and direction of this change. The results indicate that lenses worsen existing ametropia conditions. However, the use of appropriate lenses in early life can reduce and correct developing ametropia.
Vision Res. Vol. 33, No. 1, pp. 21-26. 1993
The existence of a regulatory mechanism that control... more Vision Res. Vol. 33, No. 1, pp. 21-26. 1993 The existence of a regulatory mechanism that controls the growth of the eye toward emmetropia is generally agreed upon, but such an emmetropization mechanism has never been verified experimentally. This report supports the hypothesis that emmetropization can be described as a feedback process with a first-order equation and establishes a theoretical framework for future study, experimentation, and manipulation of this elusive mechanism. The feedback hypothesis has been tested by comparing two models. The first is a first-order feedback system, the second a non-feedback model with an almost identical equation. The feedback model fits data from human subjects significantly better.
Objective: Progressive myopia in humans and lid-sutured myopia in primates have been considered t... more Objective: Progressive myopia in humans and lid-sutured myopia in primates have been considered to be different processes. This report seeks to establish the connection between progressive myopia in humans and lid suture myopia in macaque monkeys. Methods: We followed the axial length of 4 lid-sutured macaque monkeys over an 18 month period. Their axial length is directly related to myopia. We also studied the myopia progression in corrected human subjects. Macaques and humans exhibit a linear time course of myopia progression when lid-sutured or corrected with lenses, respectively. Results: A linear progression is observed in lid-sutured eyes of four macaques, r = 0.94, p < 0.05. Human progressive myopia and lid-suture myopia can be modeled by the same feedback process. In both cases the functional equivalent is the opening of the feedback loop. Conclusions: The open loop feedback process predicts a linear progression of myopia. This prediction was confirmed in human subjects and it is now confirmed in our macaque subjects. This process also explains the very rapid rate of myopia progression of lid sutured eyes. Journal of Nature and Science, 1(6):e121, 2015 Emmetropia | emmetropization | myopia | Laplace transform | feedback | ultrasound Nomenclature r = correlation coefficient p = significance level d = diopters t = time [years] s = complex variable in the Laplace or s domain k = emmetropization system time constant [years] R = uncorrected refractive error [d] A = initial refraction at birth [d] F(s) = emmetropization transfer function o(t) = system output or response [d] G(s) = forward or open loop transfer function i(t) = input to the feedback system [d] O(s) = output function in the Laplace or s domain L{ } = Laplace transform L-1 { } = inverse Laplace transform (A/k)t = open loop response function to step A input R/k = ramp slope or myopia progression rate, human [d/year] A/k = ramp slope or myopia progression rate, macaque [d/year]
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Papers by Antonio Medina
ABSTRACT
Purpose and Background
The eyeball and, in particular, the cornea deform in vitro by the application of a distending force like other visco-elastic tissue. If the force is large enough, the cornea strains beyond the elastic range, and a permanent deformation occurs. Such permanent strain is referred to as "plastic" strain. The phenomenon, however, has never been observed or produced on living tissue. This report seeks to demonstrate that the central radius of a patient’s cornea can be altered in a controlled manner designed to correct refractive errors.
Methods
To plastically deform the living cornea, we applied a vacuum to the cornea of eight rabbits and five human eyes with a novel device. This device consists of a chamber of 11 mm in diameter. The chamber is radially divided into four interconnected sub-chambers.
Results
Here we show that a strain can be achieved in vivo with a force produced by the application of the specially designed chamber where air is evacuated. An anatomical modification of the cornea of humans and rabbits was achieved. The deformation of the cornea was plastic, and therefore permanent.
Conclusions
The method described here -Pneumatic Keratology- can be used to alter the cornea by non-invasive means. A vacuum chamber with radial openings alters the collagen fibers in the stroma and flattens the cornea. A flatter cornea corrects or reduces myopia.
To confirm the prediction of emmetropization feedback theory that myopia can
be prevented by correcting the hyperopia of a child at risk of becoming myopic.
Methods
We conducted such myopia prevention treatment with twins at risk. Their
hyperopia was partially corrected by one half at age 7 and in subsequent years
until age 16.
Results
Hyperopia progressively decreased in all eyes as expected. None of the twins
developed myopia. The spherical equivalent refractions of the followed eyes
were +1 and +1.25 D at age 16. Feedback theory accurately predicted these
values.
Conclusions
The treatment of the twins with partial correction of their hyperopia was
successful. Prevention of myopia with this technique is relatively simple and
powerful. The use of this myopia prevention treatment has no adverse effects.
This prevention treatment is indicated in children with a hyperopic reserve at risk
of developing myopia.
See link for full paper.
squeezing the frequency distribution of the total
refractive errors into its sharply peaked shape has
been up-to-date unsolved. Let alone the cause of
ametropia.
After analysing refraction with age in any subject it
is clear that a servo mechanism exists and furthermore
it can be measured.
This servo can explain theoretically all kind of ametropias,
the effect of glasses and the eye refraction
of any subject from intrauterine life.
Experiments already conducted support the
theory, and the results show that they are in perfect
agreement.
From a practical point of view, both theoretical and
experimental considerations would allow us to treat
ametropic patients in order to reduce their dioptric
value.
The existence of a regulatory mechanism that controls the growth of the eye toward emmetropia is
generally agreed upon, but such an emmetropization mechanism has never been verified experimentally.
This report supports the hypothesis that emmetropization can be described as a feedback process
with a first-order equation and establishes a theoretical framework for future study, experimentation,
and manipulation of this elusive mechanism. The feedback hypothesis has been tested by comparing
two models. The first is a first-order feedback system, the second a non-feedback model with an almost
identical equation. The feedback model fits data from human subjects significantly better.
ABSTRACT
Purpose and Background
The eyeball and, in particular, the cornea deform in vitro by the application of a distending force like other visco-elastic tissue. If the force is large enough, the cornea strains beyond the elastic range, and a permanent deformation occurs. Such permanent strain is referred to as "plastic" strain. The phenomenon, however, has never been observed or produced on living tissue. This report seeks to demonstrate that the central radius of a patient’s cornea can be altered in a controlled manner designed to correct refractive errors.
Methods
To plastically deform the living cornea, we applied a vacuum to the cornea of eight rabbits and five human eyes with a novel device. This device consists of a chamber of 11 mm in diameter. The chamber is radially divided into four interconnected sub-chambers.
Results
Here we show that a strain can be achieved in vivo with a force produced by the application of the specially designed chamber where air is evacuated. An anatomical modification of the cornea of humans and rabbits was achieved. The deformation of the cornea was plastic, and therefore permanent.
Conclusions
The method described here -Pneumatic Keratology- can be used to alter the cornea by non-invasive means. A vacuum chamber with radial openings alters the collagen fibers in the stroma and flattens the cornea. A flatter cornea corrects or reduces myopia.
To confirm the prediction of emmetropization feedback theory that myopia can
be prevented by correcting the hyperopia of a child at risk of becoming myopic.
Methods
We conducted such myopia prevention treatment with twins at risk. Their
hyperopia was partially corrected by one half at age 7 and in subsequent years
until age 16.
Results
Hyperopia progressively decreased in all eyes as expected. None of the twins
developed myopia. The spherical equivalent refractions of the followed eyes
were +1 and +1.25 D at age 16. Feedback theory accurately predicted these
values.
Conclusions
The treatment of the twins with partial correction of their hyperopia was
successful. Prevention of myopia with this technique is relatively simple and
powerful. The use of this myopia prevention treatment has no adverse effects.
This prevention treatment is indicated in children with a hyperopic reserve at risk
of developing myopia.
See link for full paper.
squeezing the frequency distribution of the total
refractive errors into its sharply peaked shape has
been up-to-date unsolved. Let alone the cause of
ametropia.
After analysing refraction with age in any subject it
is clear that a servo mechanism exists and furthermore
it can be measured.
This servo can explain theoretically all kind of ametropias,
the effect of glasses and the eye refraction
of any subject from intrauterine life.
Experiments already conducted support the
theory, and the results show that they are in perfect
agreement.
From a practical point of view, both theoretical and
experimental considerations would allow us to treat
ametropic patients in order to reduce their dioptric
value.
The existence of a regulatory mechanism that controls the growth of the eye toward emmetropia is
generally agreed upon, but such an emmetropization mechanism has never been verified experimentally.
This report supports the hypothesis that emmetropization can be described as a feedback process
with a first-order equation and establishes a theoretical framework for future study, experimentation,
and manipulation of this elusive mechanism. The feedback hypothesis has been tested by comparing
two models. The first is a first-order feedback system, the second a non-feedback model with an almost
identical equation. The feedback model fits data from human subjects significantly better.