About the Tohono O'odham Vision Screening Program
In 1984, two University of Arizona ophthalmologists,
Drs. Kershner and Brick, noted that there was a high prevalence
of astigmatism in Tohono O’odham children. In 1994, Dr. Joseph
Miller, a pediatric ophthalmologist, and Dr. Velma Dobson,
a pediatric vision researcher, from the University of Arizona,
approached the Tohono O’odham Tribe with a proposal for a
program to study vision screening and astigmatism in Tohono
With the support of the Legislative Council, Drs. Miller
and Dobson submitted a proposal to the National Institutes
of Health - National Eye Institute. The proposal was funded,
and the Tohono O’odham Vision Screening Program began in 1997.
The program provided over 9,000 eye examinations to children
on the Tohono O’odham Reservation from 1997-2015. In what
follows, we outline the goals and results for each of the
5 phases of the program.
Many Tohono O’odham adults and children have high astigmatism.
Astigmatism is a condition of the eye in which the front surface
of the eye is not equally curved in all directions. The front
surface of an eye without astigmatism is equally curved, like
a ping-pong ball. The front surface of an astigmatic eye is
shaped somewhat like the surface of an egg; it is not equally
curved in all directions.
||The surface of an eye without
astigmatism is equally curved, but the surface of an eye
with astigmatism is more steeply curved in one direction.
Because of the unequal curvature, an eye with astigmatism
cannot focus things clearly, resulting in blurred vision for
objects up close or far away. For example, when looking at
the letters to the right (top), someone with astigmatism who
is not wearing eyeglasses might see the letters as shown on
Often, people with astigmatism can see well if they wear
eyeglasses or contact lenses. However, some people with astigmatism
may not see normally even with eyeglasses on. This is because
some children with astigmatism can develop amblyopia, or poor
development of the visual part of the brain. The treatment
for amblyopia is to wear eyeglasses. The eyeglasses allow
the visual part of the child’s brain to receive clear images,
and as a result, the brain develops in a way that allows the
child to see normally.
Phase I: 1997-2001
The primary goals of Phase I were:
1: To develop an effective method to screen preschoolers
for high astigmatism.
2: To determine if preschool children with high astigmatism
have amblyopia (poor vision, even when wearing eyeglasses),
and if the amblyopia improves after 3-5 months of eyeglasses
Children who attended the Tohono O’odham Early Childhood
Head Start Program were eligible to participate. Children
who enrolled in the program participated in an eye examination
and vision testing in the fall and in the spring of each year,
and children who required eyeglasses were provided with two
pair. Repairs and replacements were provided as needed.
The results indicated that the best way to identify children
who have high astigmatism (and who therefore require referral
to an eye doctor) is to use an instrument called a “keratometer”.
The instrument measures the eye for astigmatism while the
child looks at lights inside the instrument. This screening
protocol was used by the Tohono O’odham Head Start Program
for many years. However, technology has improved. There are
now instruments called “photoscreeners” that can screen for
other vision problems, in addition to astigmatism. We now
recommend use of “photoscreeners” for screening infants, toddlers,
and preschool children. A photoscreener was provided to the
Division of Early Childhood, and is currently being used to
screen preschool children on the reservation.
The results also indicated that eyeglasses improved vision
in children with astigmatism. However, children with astigmatism
still did not see as well as children who did not have astigmatism,
even when they were wearing their eyeglasses. It is possible
that these younger children had trouble wearing their eyeglasses
consistently, as they often became lost or broken, or that
they require longer than 3-5 months of eyeglass wear in order
for vision to improve.
Phase II: 2001-2005
The primary goals for Phase II were:
1: To better understand the vision problems associated
with astigmatism-related amblyopia in grade-school children.
2: To determine if younger children respond better to eyeglass
treatment than older children.
Kindergarten through 2nd grade and 4-6th grade children who
attended school on the Tohono O’odham Reservation were eligible
to participate. Upon enrollment, children participated in
an eye examination and vision testing, and a follow-up eye
examination and vision testing 1 year later. Children who
required eyeglasses were given two pair. Eyeglasses were repaired
or replaced as needed.
The results of the initial exam indicated that many of the
children had astigmatism-related amblyopia (poor development
of the visual part of the brain): Children with astigmatism
did not see as well as children who did not have astigmatism,
even when they were wearing their eyeglasses.
Previous studies suggested that younger children would show
more improvement in vision over time with eyeglass wear than
older children. It was believed that this better response
to treatment was due to the fact that young children’s brains
are more flexible and open to change, and therefore respond
better to the improved images the brain receives when glasses
are worn. The good news was that vision in children with astigmatism
improved over time with eyeglass wear and that the older children
(grades 4-6) improved as much as the younger (grade K-2) children.
Despite this improvement, we found that the children with
astigmatism still did not see as well as the children without
astigmatism, even after 1 year of eyeglass wear. This may
be due in part to poor compliance with eyeglass wear, as eyeglasses
were often lost or broken.
Phase III: 2005-2010
The primary goals of Phase III were:
1: To determine if astigmatism is prevalent among Tohono
O’odham infants and toddlers, and to determine if astigmatism
tends to increase or decrease with age.
2: To determine if blurred vision due to astigmatism in
infants and toddlers leads to poor vision later in childhood.
3: To determine if providing eyeglasses for astigmatic
preschool children leads to better vision once the children
reach elementary school.
Phase III focused on questions regarding early development
of astigmatism, and its effects on visual development in
infancy and early childhood. Children from 6 months of age
through 1st grade were eligible to participate in vision
screening and eye examinations. Children who required eyeglasses
were given two pair. Eyeglasses were repaired or replaced
Results indicated that, like older children, many Tohono
O’odham infants and toddlers have high astigmatism, and that
the astigmatism has a negative influence on their visual development:
infants/toddlers with astigmatism had poorer vision than infants/toddlers
without astigmatism, even when wearing eyeglasses to correct
We also found that astigmatism tended to decrease over time
in infants and toddlers with high astigmatism. However, from
age 3 to age 8 years there tended to be little change in astigmatism
Finally, we found that if we prescribe eyeglasses to preschool
children with astigmatism, their vision improved by the time
they reach kindergarten. However, the children with astigmatism
still did see as well as children who did not have astigmatism,
even when wearing their eyeglasses. This may be due in part
to poor compliance with eyeglass wear, as eyeglasses were
often lost or broken.
Phase IV and V: 2010-2015
The primary goals of Phase IV/V were:
1: To determine how astigmatism changes with age.
2: To determine what factors are associated with poor compliance
with eyeglass wear.
3: To determine if astigmatism makes it difficult for children
to read or perform visual-motor tasks, and to determine
if eyeglasses improve their performance.
By 2010, most of the preschool children who participated
in Phase I of the program were in high-school. We re-examined
the children who participated in earlier phases of the program
to see how their eyes have changed as they have grown. We
found that there was little change in astigmatism over time
in children from 3 through 18 years of age. This suggests
that once a child is identified as requiring eyeglasses for
astigmatism, it is likely that the child will continue to
require eyeglasses for astigmatism throughout their school
Over the years, we have found that many children do not consistently
wear their eyeglasses. We found that poor compliance with
eyeglass wear it is likely due to a combination of factors.
The most common reasons for not wearing the glasses were that
they were lost or broken, or that the child took them off
to play and did not put them back on. Relatively few children
reported that they did not wear their glasses because of teasing,
or because the glasses made things look distorted or blurry.
We have often wondered how astigmatism has affected children’s
ability to do their school work and other tasks. We examined
reading fluency and visual-motor skills in astigmatic children
both with and without their eyeglasses on. We found that reading
fluency and performance of visual motor tasks is reduced in
students with astigmatism when they are not wearing their
eyeglasses, but when they wear their eyeglasses, their reading
and visual motor performance was similar to their non-astigmatic
classmates. These results support the recommendation for full-time
eyeglass wear in astigmatic students, particularly those with
very high astigmatism.
In summary, the Tohono O’odham Vision Screening Program
has provided answers to important questions about the effects
of astigmatism on visual development, and provided the participants
with quality eye care, eyeglasses, and appropriate referral
for treatment of eye problems. Participation of members of
the Tohono O’odham Nation has made an important contribution
to our understanding astigmatism, and has provided doctors
and patients with important information about astigmatism
and how it influences the development of vision in young children.