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The Tohono O'odham
Vision Screening Program

The University of Arizona
1997-2015

About the Tohono O'odham Vision Screening Program

Introduction
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 O’odham children.

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.

Background
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.

Astigmatism Graphic 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 the bottom.

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 wear.

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 as needed.

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 the astigmatism.
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 over time.

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 years.
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.

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Funding Provided By

Sponsored By
The Tohono O’odham Nation
The University of Arizona
The National Eye Institute of the National Institutes of Health