Comparative study of visual function of
two groups with mental handicaps
(elite athletes participating at Special Olympics'97 and a sedentary group)

*Departament d'Optica i Optometria de la U.P.C.
Escola Universitaria d'Optica i Optometria de Terrassa.
Founder and technical director of the Vision Center
at the Olympic Training Center of Sant Cugat
del Vallés, Barcelona

***Centre de Visió del C.A.R. (Olympic Training Center)
de Sant Cugat del Vallés, Barcelona
Lluïsa Quevedo i Junyent *
Carme Serés i Revés *
Joan Solé i Fortó ** ***





    Different authors have reported superior visual abilities in athletes. On the other hand, no one doubts the general benefits that physical activity can bring to mentally retarded people.
    With occasion of the Special Olympics'97 celebration the authors decided to compare general visual function of two groups of subjects with mental handicaps: Special Olympics athletes and non-athletes. Although at a descriptive level we observe that the prevalence of refractive errors and strabismus was significantly higher for the sedentary population than for the special athletes, it was difficult to explain the differences in terms of benefits reported by sporting activities. Nevertheless, the authors believe that controlled physical activity offers great general benefits and probably also visual benefits to people with mental disabilities.
    Keywords: Visual function. Athletes. Mental handicap.

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    Nowadays, in our increasingly health and leisure conscious society, regular participation in sports and physical activities is widely accepted as a quality of life indicator in all population groups.

    Among the aspects of athletic conditioning in professional and amateur sports, vision care is a very important as well as a very neglected one. This fact is surprising, taking into account that vision is the process of reacting to what is seen, the signal that directs the muscles of the body to respond, providing the athlete with information as to where, how and when to perform. (Martin, 1982).

    Individuals with mental retardation usually have special difficulties practicing sports due to their frequent sensory, motor, and psychological deficits. Nevertheless, sports plays an important role in the lives of people with disabilities, providing a valuable means of augmenting rehabilitation outcomes, as well as offering opportunities for recreation, social interaction, and the pursuit of athletic excellence (Tweedy, 2002).

    Epidemiological studies have investigated the visual characteristics of children and adults with cognitive impairment or developmental delays reporting an increase in visual anomalies in this population. Woodruff, Clearly, & Bader (1980) reported that 48.8% of individuals with mental retardation required spherical correction (for myopia or hyperopia), and 37.1% required astigmatic correction. Haugen, Aasved, & Bertelsen (1995) also found a prevalence of astigmatism that exceeded 30%. McCulloch, Sludden, & McKeown (1996) reported that 41.2% of subjects in their study manifested strabismus. Black (1982) also reported a prevalence of 52.5 % for strabismus.

    Castañé, Peris & Sánchez (1995) informed of high incidence of ocular problems (58.7% hyperopia, 21.7% myopia, 19.5% astigmatism and 28% strabismus). In addition to the increased prevalence of visual problems reported in the literature, Levy (1984) stated that the population with mental retardation does not appear to receive appropriate eye care.

    Among the associations that promote the physical and emotional benefits that sports and fitness training provide to individuals with mental disabilities, we wish to emphasize the International Special Olympics movement. It began when Eunice Kennedy funded the first International Special Olympics Games, held in Chicago in 1968. Since then, Special Olympics programs have been continually developed around the world, and millions of people with mental disabilities have participated reciting the Special Olympics oath: "Let me win. But if I cannot win, let me brave in the attempt".

    More specifically, the program called "Opening the Eyes of the World" was conceived to improve the quality of life for people with mental retardation by optimizing their vision, eye health and visual skills through quality eye health care for the Special Olympic athletes. This has been accomplished by assessing the integrity of the athlete's visual system as well as visual acuity, prescribing and dispensing appropriate prescription and safety eyewear, educating the athletes, parents and coaches about the importance of the visual system for sports education, and gathering and publishing data regarding vision, visual skills and eye health of the Special Olympic population. (Official Special Olympics General Rules, 1993).

    At present, one of the most outstanding studies describing the visual characteristics of athletes with mental retardation was undertaken by Sandra Block, director of research and education of Special Olympics Opening Eyes organization, Stephen Beckerman and Paul Berman. A comprehensive vision screening was conducted at the 1995 Special Olympic World Summer Games in New Haven. Of the nine hundred and five special athletes, ranging in age from 8 to 58 years old, which completed the screening, 41.4% had never had an eye examination while 30.4% used glasses. A significant number of participants (26.7%) had visual acuity less than 20/40 (0.5).The uncorrected refractive error distribution ranged from +9.50 to -17.25 diopters, with 85.2% of athletes demonstrating refractive errors in the range of -2.00 to +2.00. Astigmatism in excess of 1 diopter was present in 28% of subjects. The prevalence of strabismus was 18.5 %. In summary, this study demonstrated that there is a need for better eye care in the Special Olympic population. (Block, Beckerman, & Berman, 1997).

    The Polytechnic University of Catalonia (U.P.C.) participated in the first overseas Special Olympics Opening Eyes, held in Seville. For five days in October 1997, Spanish and American optometrists joined together to provide quality eye care to 329 special swimmers ranging from 9 to 77 years.

    The vision screening profile had been used for the previous Special Olympics events. The vision screening began with an interview and a case history for visual and health information. Questions included date of the last eye examination and current status of corrective lenses, if worn.

    Six main areas were evaluated: distance monocular visual acuity; unilateral and alternate cover testing to detect the presence of strabismus; refractive error assessed with an autorefractor; binocular color-vision; stereopsis (depth perception) and ocular health (both external and internal).

    Case histories showed that 19.8% of the athletes had never had an eye examination. Standard spectacles were worn by 48.6% , 0.6 % wore contact lenses and 0.3% used sports frames. Visual acuity values, using the athlete's current correction showed that 38.6% had monocular visual acuity of less than 20/40 (0.5). With regard to refractive errors: 25.8 % had myopia and specifically 16.2% greater than -2.00D; 22.1% had hyperopia (7.6% > +2.00 D), and 16.2% had astigmatism in excess of 1.00D. The incidence of strabismus was 29.5% (7.3% of exotropia, 20.4 % esotropia and 1.8 % hypertropia). Finally, color vision testing reported the same ratio of anomalies as in the nonhandicapped population (0.5% for females and 4 to 5% for males), (Block, 1998).

    In the literature related to visual function in nonhandicapped athletes, there are studies suggesting that, in general, athletes' visual skills are better than those of non-athletes. (Christenson & Winkelstein 1988; De Teresa 1992; Rouse, DeLand & Christian, 1988; Stine, Arterburn, & Stern, 1982).

    In accordance with this, the authors decided to develop a pilot study with mentally retarded people not practicing any sport nor physical activity in order to investigate if it is possible to establish any link between athletic participation and "better vision" in the mentally retarded population. Thus, the objective was to compare visual characteristics of two groups with mental retardation (the previous data from athletes participating in Special Olympics'97, and a sedentary group).



    The population studied was drawn from L'HEURA, a private center for the mentally handicapped located in Terrassa (Barcelona). The subjects were 40 individuals affected with various syndromes and neurological conditions. Their ages ranged from 10 to 19 and there was a wide range of IQ. None of them practiced any sport nor followed any physical activity program.


    Based on the Special Olympics Opening Eyes protocols (Block, 1997), the optometric examination sequence was as follows:

  1. Case history (including data of the last eye examination) was done.

  2. Monocular visual acuity at far (3 meters) with LEA symbols (Precision Vision, Illinois) was determined. The passing criterion was a performance of 20/40 in each eye.

  3. Ocular refraction (to determine the amount of myopia, hyperopia and/or astigmatism) was assessed with the Nidek Autorefractor (INDO, Spain).

  4. Binocular color-vision testing was completed with the Ishihara color plates for illiterates (Kaneara & Co., Japan). The subject passed the test if he or she was able to trace all the winding lines of the plates.

  5. Cover test was completed at 40 cm. The target used to maintain fixation was a sticker with small details. The presence or absence of strabismus was recorded, and its direction, as well as the presence of nystagmus.


    The ocular findings of the study are the following (see table 1):

Table 1

    Case histories showed that 26.6% of the subjects had never had an eye examination. Spectacles were worn by 43.3%, although 76.8% of them were not appropriately corrected by more than 1 Diopter (either hyperopes, myopes or astigmatics). Visual acuity values, using the subject's current correction showed that 58.3% had monocular visual acuity less than 20/40 (0.5). With regard to refractive errors: 20% had myopia ( 10% superior to -2.00D), 53.3% had hyperopia (30% over +2.00), and 26.6% had astigmatism in excess of 1.00D. The incidence of strabismus was 46.4% (20% exotropia, 26.2% esotropia and 6.6% hypertropia associated), as well as 6.6% of observed nistagmus. Finally, color vision testing did not find anomalies, even though 6.6% of the sample did not pass the exam due to the lack of collaboration.

Discussion and Conclusions

    At a descriptive level, the reported data of the Special Olympics'97 show that although the prevalence of refractive errors and strabismus is significantly higher than those expected in a nonhandicapped population (Borish 1970, Gordon 1990, Kinge & Midelfart, 1994), it is generally much less than those found in the present study undertaken specifically with a group of mentally disabled sedentary people.

    Although definitive causal relations between sporting activity and superior visual abilities are always difficult to establish (Hazel, 1995) when comparing subjects from the nonhandicapped population, it is frequently reported that, in general, athletes' visual skills are better than non-athletes'.

    From the data obtained from both groups of mentally disabled subjects, the differences observed in visual indicators can not be explained. Firstly, there is the difficulty of making statements about persons with relatively unknown brain damage. On the other hand, we do not know some important aspects such as how many hours per day the Special Olympics athletes practiced physical activity, what the average ages were (even though it can be easily guessed that they were older than the sedentary sample). Finally, we are aware of the difficulties of making statements when comparing samples of such a big different size.

    On the other hand, the authors believe that controlled physical activity offers great general benefits and probably also visual benefits, to mentally disabled people, as well as to nonhandicapped people.

    The importance of providing adequate optometric care is without question, separate from the general management of sensory, motor or psychological deficits to enhance the quality of life of this population.


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  • Block, S.S. (1998). Review of the procedures and data of the Special Olympics Opening Eyes held in Seville, 97. Seville: Personal communication.

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  • The authors wish to thank Dr. Sandra Block, the Special Olympic Opening Eyes organization and Special Olympics España for allowing us to use the data obtained from the study.

  • Also, we would like to thank INDO Spain for providing us with the equipment needed to develop the pilot study, and L'HEURA for their invaluable collaboration.

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