Optical Defocus to Stimulate Eye Elongation in Hyperopia
| Status: | Active, not recruiting |
|---|---|
| Conditions: | Ocular |
| Therapuetic Areas: | Ophthalmology |
| Healthy: | No |
| Age Range: | 5 - 12 |
| Updated: | 11/30/2017 |
| Start Date: | January 2015 |
| End Date: | September 2018 |
Use of Multifocal Contact Lenses to Stimulate Axial Elongation in Axial Hyperopia
Axial hyperopia results when the length of the eye is too short for the eye to properly focus
distance objects on the retina while the focusing system is relaxed. Emmetropization is the
process by which the eye actively adjusts various components of the eye to gradually improve
the focus of the eye. Emmetropization frequently involves either an increase or a decrease in
the growth of the eye, particularly during infancy and childhood. Numerous animal studies
suggest that if an animal is exposed to retinal images located behind the retina either
centrally or peripherally, the eye will grow in the direction of the focused image. If an
abnormally short eye has resulted in hyperopia, exposing such an eye to retinal images
partially located behind the retina might encourage axial elongation, thus reducing the
hyperopia.
distance objects on the retina while the focusing system is relaxed. Emmetropization is the
process by which the eye actively adjusts various components of the eye to gradually improve
the focus of the eye. Emmetropization frequently involves either an increase or a decrease in
the growth of the eye, particularly during infancy and childhood. Numerous animal studies
suggest that if an animal is exposed to retinal images located behind the retina either
centrally or peripherally, the eye will grow in the direction of the focused image. If an
abnormally short eye has resulted in hyperopia, exposing such an eye to retinal images
partially located behind the retina might encourage axial elongation, thus reducing the
hyperopia.
Hyperopia or farsightedness may cause distance vision and near vision to be blurred.
Depending on the severity of the condition and the age of the patient and the status of the
binocular vision system, hyperopia can also cause fatigue, asthenopia, headaches, double
vision, and amblyopia. Low to moderate amounts of hyperopia rarely cause much difficulty in
the young person, but will eventually cause significant near vision problems as the patient
ages. Hyperopia can be caused by the eye being too short (axial hyperopia) or by the cornea
being too flat or the crystalline lens being to weak (refractive hyperopia). It has been
established by the PI that axial growth can be dramatically lessened in children and
adolescents with myopia through the use of bifocal contact lenses prescribed in a particular
way (The CONTROL Study). Studies by Earl Smith, O.D., Ph.D. have suggested that multi-zonal
contact lenses that provide proper axial focus while manipulating peripheral defocus can
either discourage or encourage axial growth to treat myopia or hyperopia respectively. In the
present study, simultaneous vision bifocal soft contact lenses will be used to encourage
axial growth in hyperopic children and adolescents with axial hyperopia in an effort to
reduce hyperopia. Subjects will be randomly assigned to wear either bifocal soft contact
lenses or single vision soft lenses. The bifocal contact lenses will be prescribed to provide
for clear central vision at both distance and near with the near zone of the contact, thus
exposing the retina to hyperopic defocus from the distance zone.
Depending on the severity of the condition and the age of the patient and the status of the
binocular vision system, hyperopia can also cause fatigue, asthenopia, headaches, double
vision, and amblyopia. Low to moderate amounts of hyperopia rarely cause much difficulty in
the young person, but will eventually cause significant near vision problems as the patient
ages. Hyperopia can be caused by the eye being too short (axial hyperopia) or by the cornea
being too flat or the crystalline lens being to weak (refractive hyperopia). It has been
established by the PI that axial growth can be dramatically lessened in children and
adolescents with myopia through the use of bifocal contact lenses prescribed in a particular
way (The CONTROL Study). Studies by Earl Smith, O.D., Ph.D. have suggested that multi-zonal
contact lenses that provide proper axial focus while manipulating peripheral defocus can
either discourage or encourage axial growth to treat myopia or hyperopia respectively. In the
present study, simultaneous vision bifocal soft contact lenses will be used to encourage
axial growth in hyperopic children and adolescents with axial hyperopia in an effort to
reduce hyperopia. Subjects will be randomly assigned to wear either bifocal soft contact
lenses or single vision soft lenses. The bifocal contact lenses will be prescribed to provide
for clear central vision at both distance and near with the near zone of the contact, thus
exposing the retina to hyperopic defocus from the distance zone.
Inclusion Criteria:
- Aged 5-12
- Hyperopia > +1.25 each eye (cycloplegic refraction)
- Ability to wear soft contact lenses
Exclusion Criteria:
- Amblyopia
- Strabismus
- Astigmatism > 1.00 diopters
- Axial Length > 24.00 mm
We found this trial at
1
site
San Bruno, California 94066
Principal Investigator: Thomas A Aller, O.D.
Phone: 650-871-1816
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