– Written by Ciro Winckler and Andrea Jacusiel Miranda, Brazil

AETIOLOGY

Visual impairment (VI) is caused by impairments to the ocular globe, optical nerve or visual cortex, resulting in a functional limitation in the interaction of the person with the environment. This impairment can be divided into blindness and low vision, according to the degree of remaining vision. Blindness encompasses the spectrum from complete vision loss to the perception of light and colour, but in a non-functional condition for motor learning. Low vision is defined as the ability to perceive light, colour and form, but has limitations in the perception of space, details, movement, three-dimensional and compound shapes¹.

It should be noted, of course, that there are notable discrepancies between the prevalence of various aetiologies of visual impairment in the general population versus para athletes. This difference is due mainly to the mean age of competing athletes as well as world regions for which para sport is highly developed. Socioeconomic development, the availability of primary healthcare and eye care services highly determine the frequency with which these pathologies are recognised according to each region².

PARALYMPIC SPORTS

The history of sport participation by persons with VI dates back to the beginning of 20th century in athletics events, baseball and gymnastics taking place in the United States³. Today, athletes with VI compete in the summer Paralympic sports of athletics, cycling, equestrian, football 5-a-side, goalball, judo, rowing, swimming and triathlon, as well as the winter sports of alpine skiing, biathlon and cross country skiing⁴. Athletes with VI are divided into three sporting classes. The minimal disability criteria to be eligible for participation in para sport is based on the American definition of legal blindness (visual acuity in 20/200)⁵.

The current classification system is based on factors related to both visual acuity and visual field (Table 2). While this classification system is based on biomedical concepts only, there is a great demand for adjustments to be made so that there is an evaluation of the visual functionality applied to each sport⁷.

Unique characteristics of the Paralympic classification system for athletes with VI are noted in Table 3. Indeed, each Paralympic sport varies with regard to type of support offered to athletes with VI. In some sports the athletes compete only in their sport class and, in others, they compete in a single class (all classes together). Additionally, in some sports, blindfolds are utilised to completely obscure the vision (and ensure equal level of impairment) for all athletes, such as the B1 class, or for all athletes during competitions with combined classes.

Finally, some sports allow for an escort-athlete such as a guide or pilot to assist the athlete with VI. The function of the guide or pilot is to support the athlete in their limitation – visual orientation of the environment. For example, in the sport of athletics, the role of the guide is to run together with the athlete at the same pace, read the environment and translate this to the athlete with verbal and tactile cues.

CLINICAL MANAGEMENT

There are several points that are important to keep in mind when providing clinical care for athletes with VI. Among the challenges facing the medical staff are two basic principles of clinical practice: empathy and communication. Nonverbal cues play an important role in physician-patient interactions, and often these rely on visual information^8,9. VI athletes are often not able to pick up visual cues from medical staff. And for those with onset of the impairment early in life, who have not learned the socially accepted facial expressions associated with each emotion or with what one may want to infer, may it be through a smile of comprehension or a frown denoting doubt on what is being said. For this reason, when interacting with athletes with VI, one must pay special attention to voice intonation, both when speaking and when listening, as well as one’s direction when speaking. For example, not speaking directly at the athlete (as when looking at a computer screen and asking questions at the same time) might be interpreted as lack of attention. Touch can be used as a tool to better communicate, as it denotes interest and may be used to anatomically explain an injury or better define where a pain is felt (always previously explaining where one is going to touch and having asked permission to do so¹⁰).

Persons with blindness, particularly in congenital or early onset, may manifest mannerisms¹⁵. These are repetitive behaviours or movements that do not appear to be directed towards obtaining a goal, for example, eye manipulation, body rocking or flicking fingers in front of the eyes while staring at light. These are more frequent when the person with blindness is experiencing stress or anxiety.

As with all Paralympic sports, the physician must consider anti-doping regulations at all times, including which substances and methods are included on the World Anti-Doping Agency (WADA) Prohibited List, as well as the impact of all prescribed substances on sports performance. Specific to athletes with VI, providers must take care with use of acetazolamide and beta-blocker eye drops, often prescribed for glaucoma, both of which are prohibited substances. Insulin, often prescribed for glycaemic control in individuals with diabetes mellitus and diabetic retinopathy, is also a prohibited substance. Each case must be considered individually to determine whether such medications are ideal for treatment of the disease process, while also taking into consideration athlete performance.

The understanding of the VI mechanism is fundamental as some types of exercises by persons with specific impairments, without adjustments to the training protocol or environment, may worsen the impairment. For example, contact sports such as goalball and judo should not be recommended for those at risk for retinal detachment¹¹. If contact sports are pursued by at-risk individuals, head protection should be used. In some more severe cases, jump training can induce retinal detachment. Precautions should also be taken for athletes with diabetic retinopathy as heavy weightlifting dramatically increases blood pressure and may cause retinal bleeding^12,13. Athletes with glaucoma require special attention during intense physical exercise, as changes in body position and increased respiratory volumes, especially with Valsalva manoeuvre, may place the athlete at risk¹⁴. Finally, it is important to note that the reduced visual stimulus on the visual cortex may trigger what is known as Claude Bonnet syndrome, which can cause visual hallucinations, most commonly in the image of a person, and affects between 0.4 and 14% of people who lose their vision during their lifetime^16,17. It is a condition analogous to the “phantom limb syndrome”¹⁶. The traditional treatment approach is pharmacological intervention¹⁶.

Another important point to note is that athletes with no light perception (full blindness) may experience a disruption in their circadian rhythms¹⁸. This has the potential to result in:

·      Reduced peak performance, simple reaction time and body temperature regulation throughout the day¹⁹.

·      Altered concentration and distribution of melatonin throughout the day¹⁸.

·      A delay in the prepubertal growth period, especially in women²⁰.

·      Later menarche in women²¹.

·      Sleep disorders²².

Furthermore, it is a challenge for B1 and B2 athletes to self-monitor hydration from the standpoint of urine colour and volume²³. Although an imperfect measure, some athletes use the smell of the urine as a guide, since a stronger smell of urine is usually associated with a higher concentration.

All of the above conditions can impact the performance, training and recovery of the athlete with VI. They also play a major role when travelling to different time zones for competition. Adjustments are necessary to minimise the effects on training quality and performance.

THE IMPACT OF VISUAL IMPAIRMENT ON PHYSICAL CAPACITY

Inherently, the presence of VI modifies the quantity of visual information received and limits one’s perception of environment. However, this is not only due to lack of visual information, but also due to limited exposure to incidental information over time²⁴. Compensatory strategies are necessary to minimise resultant limitations in motor control and the spatial orientation.

Visual impairment interferes in a significant way on the accomplishment of specific aspects of performance in non-trained individuals, which differs from the pattern seen in trained athletes²⁵. With this notion as a starting point, Figure 1 provides a summary of the pattern of motor responses observed in athletes with VI and how it is related to the development of physical abilities in this population.

INJURY EPIDEMIOLOGY

Recent evidence demonstrate higher injury rates in athletes with VI that compete in summer sports. At the 2012 Summer Paralympics Games the highest injury incidence rates was found in football 5-a-side, followed by powerlifting, goalball, wheelchair fencing, wheelchair rugby, athletics and judo¹. Of the seven sports with the highest injury incidence rate, three were practiced exclusively by athletes with VI and a fourth (athletics) is inclusive of all three VI classes.

In general, injuries to the lower limb, followed by the upper limb, were more frequent in athletes with VI^40,41. Acute traumatic injuries were particularly prevalent in football 5-a-side^41,42. This may be related to the VI, making athletes more vulnerable to bump into other players (with lack of a protective reflex), barriers in the training and competition area or objects on the field⁴¹. The same rationale explains the higher incidence of lesions of the feet and legs that occur during daily activities in VI athletes, not directly related to sports²³. Additional evidence reveals that the greater the VI, the higher the prevalence of injury in an athlete population⁴³. This can be related to the fact that postural stability is affected by vision and proprioception in blind individuals tends to be worse than in those with partial vision resulting in abnormal gait and biomechanics, which can lead to injuries⁴³.

CONCLUSION AND PRACTICAL APPLICATIONS

Although the presence of VI may impact the performance of the athlete, sport-specific training and excellence in sports medicine services may be helpful in mitigating any detrimental effects. This process is guided by knowledge regarding the aetiology of VI as well as its consequences on short- and long-term performance. From a practical standpoint, it is fundamental in this process to provide excellent spatial orientation, adequate stimulation and an efficient channel of communication with sports medicine providers.

Acknowledgment

The authors wish to extend their deepest gratitude to Brazilian Paralympic Academy/APB and National Counsel of Technological and Scientific Development/CAPES/Brazil

Ciro Winckler Ph.D.

Sport Science Coordinator, Brazilian Paralympic Committee

Professor, São Paulo Federal University

São Paulo, Brazil

Andrea Jacusiel Miranda M.D.

Medical Doctor, Brazilian Paralympic Committee

Contact: ciro@cpb.org.br

References

1.Martín M, Bueno S. Deficiência visual: aspectos psicoevolutivos e educativos. São Paulo: Editora Santos; 2003.

2.World Health Organization. Global data on visual impairments 2010. Geneva, Switzerland: World Health Organization, 2012.

3.Bailey S. Athlete First: A history of the Paralympic Movement. Chischester: John Wiley & Sons, Ltd; 2008. 281 p.

4.IPC Sports .[cited 2017 Feb 20]. Available from: https://www. paralympic.org/sports

5.Sherrill; C, Adams-Mushett C, Jones JA. Classification and others issues in spots for blind, cerebral palsy, les autres and amputee athletes. In: SHERRILL C, editor. The 1984 Olympic Scientific Congress Proceeding. Champaign: Human Kinetics; 1986. p. 113–30.

6.IBSA. IBSA classification Manual. [cited 2017 Feb 20]. Available from: http://www.ibsasport.org/documents/files/144-1-IBSA-Classification-Manual-classifiers.pdf

7.Ravensbergen HJC, Mann DL, Kamper SJ. Expert consensus statement to guide the evidence-based classification of Paralympic athletes with vision impairment: a Delphi study. Br J Sports Med 2016;50(7):386–91.

8. Travaline JM, Ruchinskas R, Alonzo GED. Patient-Physician Communication: Why and How. JAOA. 2005;105(1):13–8.

9. Singer HK, Ruchinskas RA, Riley KC, Broshek DK, Barth JT. The psychological impact of end-stage lung disease. Chest. 2001;120(4):1246–52.

10. Pagliuca LMF, Macêdo-Costa KN de F, Rebouças CB de A, Almeida PC de, Sampaio AFA. Validação das diretrizes gerais de comunicação do enfermeiro com o cego. Rev Bras Enferm 2014. 2014;67(5):715–21.

11.Leivo T, Haavisto AK, Sahraravand A. Sports-related eye injuries: The current picture. Acta Ophthalmol. 2015;93(3):224–31.

12.American Diabetes Association (2004). Physical activity, exercise and diabetes. Diabetes Care, 2004;27(1), S58–S62.

13.Eneh A, Almeida D. Valsalva hemorrhagic retinopathy during labour: A case report and literature review. Can J Ophthalmol. 2013;48(6):145–7.

14.McMonnies CW. Intraocular pressure and glaucoma: Is physical exercise beneficial or a risk? J Optom. Spanish General Council of Optometry; 2016;9(3):139–47.

15.Molloy A, Rowe FJ. Manneristic Behaviors of Visually Impaired Children. Strabismus. 2011;19(3):77–84.

16.Rovner BW. The Charles Bonnet syndrome: a review of recent research. Curr Opin Ophthalmol2006;17(3):275–7.

17.Pang L. Hallucinations Experienced by Visually Impaired: Charles Bonnet Syndrome. Optom Vis Sci. 2016;93(11): 1466Y-1478.

18.Aubin S, Kupers R, Ptito M, Jennum P. Melatonin and cortisol profiles in the absence of light perception. Behav Brain Res. 2017;317:515–21.

19.Squarcini CFR, Pires MLN, Lopes C, Benedito-Silva AA ´lia, Esteves AM, Cornelissen-Guillaume G, et al. Free-running circadian rhythms of muscle strength, reaction time, and body temperature in totally blind people. Eur J Appl Physiol 2013;113(1):157–65.

20.Bellastella A, Sinisi AA, Raiola C, Perrone L, Lorio S, Parlato F, et al. Blindness influences the growth of institutionalized prepubertal subjects. J Endocrinol Invest. 1989;12(9):605–9.

21.Flynn-Evans EE, Stevens RG, Tabandeh H, Schernhammer ES, Lockley SW. Effect of light perception on menarche in blind women. Ophthalmic Epidemiol. 2009;16(4):243–8.

22.Tamura N, Sasai-Sakuma T, Morita Y, Okawa M, Inoue S, Inoue Y. A nationwide cross-sectional survey of sleep-related problems in Japanese visually impaired patients: prevalence and association with health-related quality of life. J Clin Sleep Med 2016;12(12):1659–1667.

23.Webborn N, Van De Vliet P. Paralympic medicine. Lancet. 2012;380(9836):65–71.

24. Sonksen PM, Dale N. Visual impairment in infancy: impact on neurodevelopmental and neurobiological processes. Dev Med Child Neurol. 2002;44:782–91.

25.Killebrew S, Petrella J, Jung A, Hensarling R. The effect of loss of visual input on muscle power in resistance trained and untrained young men and women. J Strength Cond Res. 2013;27(2):495–500.

26.Malone L a, Sanders RH, Schiltz JH, Steadward RD. Effects of visual impairment on stroke parameters in Paralympic swimmers. Med Sci Sports Exerc .2001;33(12):2098–103.

27.Pereira L, Winckler C, Abad CCC, Kobal R, Kitamura K, Veríssimo A, et al. Power and Speed Differences Between Brazilian Paralympic Sprinters With Visual Impairment and Their Guides. Adapt Phys Activ Q. 2016;33(4):311–23.

28.Loturco I, Winckler C, Kobal R, Cal Abad CC, Kitamura K, Veríssimo AW, et al. Performance changes and relationship between vertical jump measures and actual sprint performance in elite sprinters with visual impairment throughout a Parapan American games training season. Front Physiol .2015;6:1–8.

29.Makris VI, Yee RD, Langefeld CD, Chappell AS, Slemenda CW. Visual loss and performance in blind athletes. Med Sci Sport Exerc .1993;25(2):265–9.

30.Theodorou A, Skordilis E, Plainis S, Panoutsakopoulos V, Panteli F. Influence of visual impairment level on the regulatory mechanism used during the approach phase of a long jump. Percept Mot Skills .2013;117(1):31–45.

31.Molik B, Morgulec-Adamowicz N, Kosmol A, Perkowski K, Bednarczuk G, Skowronski W, et al. Game Performance Evaluation in Male Goalball Players. J Hum Kinet .2015;48:43–51.

32. Ray CT, Horvat M, Croce R, Christopher Mason R, Wolf SL. The impact of vision loss on postural stability and balance strategies in individuals with profound vision loss. Gait Posture. 2008;28(1):58–61.

33.Aydoğ E, Aydoğ S, Çakci a., Doral M. Dynamic Postural Stability in Blind Athletes Using The Biodex Stability System. Int J Sports Med. 2006;27(5):415–8.

34.Loturco I, Nakamura FY, Winckler C, Bragança JR, da Fonseca RA, Filho JM, et al. Strength-Power Performance Of Visually Impaired Paralympic And Olympic Judo Athletes From The Brazilian National Team: A Comparative Study. J Strength Cond Res. 2017;31(3):743–749.

35.Malwina KA, Krzysztof M, Piotr Z. Visual Impairment does not Limit Training Effects in Development of Aerobic and Anaerobic Capacity in Tandem Cyclists. J Hum Kinet. 2015;48(1):87–97.

36.Campos LFCC, Costa e Silva AA, Santos LGTF, Costa LT, Montagner PC, Borin JP, et al. Effects of training in physical fitness and body composition of the brazilian 5-a-side football team. Rev Andaluza Med del Deport .Elsevier; 2013;6(3):91–5.

37.Hopkins WG, Gaeta H, Thomas AC, Hill PM. Physical fitness of blind and sighted children. European journal of applied physiology and occupational physiology. 1987. p. 69–73.

38.Koustriava E, Papadopoulos K. Are there relationships among different spatial skills of individuals with blindness? Res Dev Disabil.; 2012;33(6):2164–76.

39.Aslan UB, Calik BB, Kitis A. The effect of gender and level of vision on the physical activity level of children and adolescents with visual impairment. Res Dev Disabil. 2012;33(6):1799–804

40.Willick SE, Webborn N, Emery C, Blauwet CA, Pit-Grosheide P, Stomphorst J, et al. The epidemiology of injuries at the London 2012 Paralympic Games. Br J Sports Med .2013 10;47(7):426 LP-432.

41.Magno M, Duarte E, Costa E Silva AA, Silva HG da, Vital R. Aspects of sports injuries in athletes with visual impairment. Rev Bras Med do Esporte. 2011;17(340):319–23. 1.            

42.Magno E Silva MP, Morato MP, Bilzon JLJ, Duarte E. Sports injuries in Brazilian blind footballers. Int J Sports Med. 2013;34(3):239–43.

43.Magno MP, Winckler C, Athayde A, Silva CE, Bilzon J, Duarte E, et al. Sports injuries in paralympic track and field athletes with visual impairment. Med Sci Sports Exerc. 2013;45(5):908–13.

Image by Andrew steele (Colour correction/crop)