What Causes Color Blindness?

Patient Presentation
A 9-month-old female came to clinic for her health maintenance visit. As part of the interview the physician asked if the parents had any concerns about her hearing or vision.
The father said no, but that he had a family history of color blindness and was wondering if she needed to be tested for it.
The family history revealed that the father’s brother and maternal uncle both were red-green color blind.
The pertinent physical exam revealed a developmentally normal female with growth parameters in the 10-50%.
Her visual acuity was grossly normal by fixing and following objects appropriately, and in viewing a book in her lap.
She had normal extra ocular movements bilaterally and her optic disc margins were sharp and the blood vessels appeared normal.
The diagnosis of a healthy female was made and after reviewing a PUBMED literature search, the physician told the parents that it was most likely that the daughter did not have red-green color blindness because it was an X-linked genetic disease and the father himself usually would have to be affected.
The parents were also told that there were potentially other inherited forms as well but that testing at this time was not possible and that as she grew older the testing would be more reliable.
The parents were told to treat her like a normal child and to bring any concerns about her vision including possible color problems back to the physician’s attention.

Discussion
Color blindness or impaired color vision is common. Red-green color impairments affect 6-10% of males and 0.4 – 0.7% of females.

Screening is often done using Ishihara charts which are pictures of various size spots with hidden wavy lines or numbers. The lines or numbers are read differently by those affected or may not be able to be read at all.
They can be used for children as young as 4 years. The wavy line charts have a higher incidence of errors, but are also more commonly used with younger children. Five errors or more on the first 13 Ishihara plates necessitates referral for additional testing.
Sometimes matching colors can be used in young children but it is not very reliable.

Colors are used in all types of teaching and therefore a child or adolescent may have some problems with the instruction methods used from pre-school through secondary education.
The impact for an individual child varies. Some studies have shown that children with other learning difficulties may have a higher or lower rate of impaired color vision.
Even in the field of art, there are several well known artists who were affected including Carriere, Léger, Whistler and possibly Constable and Mondrian.

Impaired color vision may have an affect on the type of career opportunities available to these children. In the United Kingdom, people are advised against certain occupations including electrical work, electronics, fabric industry, navigators, pilots, train drivers, and certain jobs in the armed forces and police.
The British Paediatric Association recommends screening at age 5, and at 11-12 years or up to 14 years. The American Academy of Pediatrics does not have a recommendation regarding color vision screening.

Learning Point
There are 3 primary color cones in the eye – red, blue and green. When gradiations of the different cones are activated, different colors are seen. For example, orange light mainly stimulates red cones and stimulates some green cones.
Depending on which cone system is defective, these are termed protanopia (red), deuteranopia (blue) and tritanopia (green). Usually one of the cone systems is affected, but there can also be a diminished response by the cones to the color stimuli.

Impaired color vision is mainly caused by an X-linked recessive inheritance pattern. Women (8%) are carriers and males are mainly affected. There can also be complex forms where mosaicism can be found and also an incompletely autosomal dominant form.

Questions for Further Discussion
1. How common is blindness in children?
2. What different methods are available for screening for visual defects in children of different ages?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Information prescriptions for patients can be found at MEDLINEplus for these topics: Eye Diseases and Vision Impairment and Blindness

To view current news articles on this topic check Google News.

Gordon M. Colour Blindness. Public Health. 1998;112:81-84.

Committee on Practice and Ambulatory Medicine, Section on Ophthalmology
Eye Examination and Vision Screening in Infants, Children, and Young Adults.
Pediatrics. 1996;98:153-157. Available from the Internet at http://aappolicy.aappublications.org/cgi/reprint/pediatrics;98/1/153 (rev. 1996, cited May 11, 2006).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    6. Information technology to support patient care decisions and patient education is used.

    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.

  • Systems Based Practice

    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    May 29, 2006

  • Can I Use Creatine?

    Patient Presentation
    A 13-year-old male came to clinic for his sports physical. During the interview he asked about using creatine to help him with his weight training for football.
    He said that he didn’t know much about it, just that other boys were taking it and they said it would increase his size and he would be able play football better.
    He denied taking any supplements or other performance enhancing substances or other complementary/alternative medicines.
    He was otherwise healthy and the interview revealed no other concerns.
    The pertinent physical exam showed a healthy male with weight at the 75% and a height at the 90% for age. He was tanner 3 for pubertal development.
    The diagnosis of a healthy male was confirmed.
    He was counseled that although creatine was not illegal to take, there was almost no information in adolescents if it actually worked and there were potential side effects such as nausea and vomiting and dehydration.
    He was also reminded that if he had these side effects then he wouldn’t be able to train or participate. There was also the cost of the creatine.
    He was reminded that he could be strong and beat his competitors without creatine or other supplements or performance enhancing drugs.
    He was counseled that these supplements are of unknown purity and may or may not contain what is on the label.
    He was reminded that proper strength, conditioning and a well-balanced diet including extra calories, extra carbohydrates during workouts, and extra protein after workouts are the best way to build his strength.

    Discussion
    Performance enhancing substances or ergogenic substances are supplements or drugs used to enhance athletic performance. They are widely used because of the desire to be strong, look better, improve overall performance and because of peer pressure.
    They are commonly classified as metabolic stimulants (e.g. Ephedra) or anabolic agents (e.g. anabolic-androgenic steroids, prohormones, protein supplements and creatine).

    Few if any medical research studies with these substances have been performed on children or adolescents. What little research is available was done almost exclusively in adult populations.
    Nutritional supplements are not regulated, controlled, or have any oversight by the FDA or other government agencies.
    Therefore, a supplement may or may not have the labeled substances in it and the amounts listed may or may not be accurate.

    When counseling adolescents it helps to emphasize the current or near future effects. For example, for anabolic-androgenic steroids emphasize the decreased tendon strength (i.e. risk for rupture) and the irreversibility of gynecomastia and virilization rather than the malignant risk.
    Emphasis on what adolescents can do, such as proper strengthening and conditioning along with eating a well-balanced diet including extra calories, extra carbohydrates during workouts, and extra protein after workouts may be helpful.

    Learning Point
    Some of the common performance enhancing substances are listed below.

    Creatine

    • Action: amino acid compound synthesized in skeletal muscle that facilitates regeneration of ATP needed for muscle contraction
    • Proposed effects: delays workout fatigue, promotes weight gain, improves performance for sports needing short bursts of energy (e.g. weight lifting, sprinting, etc.)
    • Medical research: increases workout capacity for certain short burst energy sports, increases weight mainly through water retention, improves physiologic response to resistance training, does not improve endurance
    • Potential side effects: muscle and stomach cramps, nausea and diarrhea, dehydration, renal overload with rare case reports of renal failure
    • Legal: Not banned by sports governing organizations, but the National Collegiate Athletic Association prohibits distribution at training facilities

    Protein supplements

    • Action: increases dietary protein intake
    • Proposed effects: increase lean muscle mass, strength and power, promotes weight gain
    • Medical research: does not build muscle strength or mass by itself, requires increased calorie and carbohydrate intake for strength and muscle mass increases, weight gain varies depending on the athlete’s routine diet
    • Potential side effects: antedoctal reports of renal problems
    • Legal: not banned by sports governing organizations

    Prohormones

    • Names: Androstenedione and DHEA
    • Action: hormone precursors to testosterone
    • Proposed effects: increases strength, improves performance and builds muscle
    • Medical research: in moderate doses does not increase testosterone, in high doses may increase testosterone, not proven to increase strength, muscle mass or performance
    • Potential side effects: same as anabolic-androgenic steroids, increased estrogen effect and therefore may increase hormone-sensitive malignancies
    • Legal: Androstenedione is banned by sports governing organizations and is a controlled substance by the Federal Drug Administration (FDA). DHEA is available as a nutritional supplement and therefore is not regulated.

    Anabolic-androgenic steroids

    • Action: increases protein synthesis, enhanced development of male secondary sex characteristics. All anabolic steroids are also androgenic.
    • Proposed effects: increases strength, improves performance and builds muscle
    • Medicalresearch: increases muscle mass and strength at high doses, does not increase endurance, not proven to improve performance
    • Potential side effects:
      • Cardiovascular: cardiomyopathy, hypertension, lipid profile changes (decreased HDL, increased LDL)
      • Endocrine/reproductive: gynecomastia in males (irreversible), precocious puberty, testicular atrophy, virilization in females (irreversible)
      • Gastrointestinal: liver enzyme elevation, jaundice, possible malignancy
      • Musculoskeletal: premature closure of growth plates, decreased tendon strength
      • Psychological/behavioral – these problems can last up to one year after the steroids are stopped: mood swings, aggressive behavior (“roid rage”) depression and/or suicide, psychosis, addiction/dependence and strong correlation with other drug use
    • Legal: banned by sports governing organizations, are controlled substances by the FDA

    Ephedra

    • Herbal name: ma huang
    • Action: sympathomimetic which acts on alpha and beta adrenergic receptors
    • Proposed effects: burns fat, increases energy, decreases appetite, delays workout fatigue and improves performance and concentration
    • Medical research: burns fat when combined with high-doses of caffeine. It may delay fatigue but this is not proven.
    • Potential side effects (which can be potentiated with caffeine): include heart attack, hypertension, stroke, seizure, sudden death and heat stroke
    • Legal: banned by sports governing associations, and banned by the FDA

    Questions for Further Discussion
    1. What are the costs of common performance enhancing substances?
    2. Where can common performance enhancing substances be obtained?
    3. What performance enhancing substances are tested for by different sports governing organizations?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topics: Anabolic Steroids and Herbal Medicine
    and at Pediatric Common Questions, Quick Answers for this topic: Substance Abuse.

    To view current news articles on this topic check Google News.

    Kreider RB. Effects of creatine supplementation on performance and training adaptations. Mol Cell Biochem. 2003 Feb;244(1-2):89-94.

    American Academy of Pediatrics. Committee on Sports Medicine and Fitness Policy
    Statement. Use of Performance-Enhancing Substances. Pediatrics. 2005;115:1103-1106.

    LaBella CR. Ergogenic Substances. Pediatric Academic Societies Meeting, San Francisco CA. April 30, 2006.

    ACGME Competencies Highlighted by Case

  • Patient Care

    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.

    5. Patients and their families are counseled and educated.

    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.

  • Interpersonal and Communication Skills
    17. A therapeutic and ethically sound relationship with patients is created and sustained.

  • Systems Based Practice

    25. Quality patient care and assisting patients in dealing with system complexities is advocated.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    May 22, 2006

  • What is the Differential Diagnosis of Scrotal Swelling?

    Patient Presentation
    A term male infant was born by vaginal delivery without complications. During his physical examination it was noted that his left scrotum appeared swollen.
    The scrotum transilluminated light, but no testicle could be palpated. The right testicle and scrotum were normal as was the rest of his examination.
    The patient’s clinical course over the next day showed an slightly fussy infant with a bluish hue to the left scrotum, but no other changes in his examination.
    Urology was consulted and an ultrasound was ordered to rule out testicular torsion. The diagnosis of left hydrocele with no testicular torsion and normal vascular flow was made. He will followup with his regular physician and
    return to urology if it does not improve in 6 months.


    Figure 38 – Longitudinal color and pulse-wave doppler ultrasound images of the right and left testicles reveal normal arterial blood flow to each testicle, which rules out testicular torsion. A very small right hydrocoele and a very large left hydrocele are also seen.

    Discussion
    Hydroceles are one of the most common causes of painless scrotal swelling. It is caused by fluid accumulations in the tunica vaginalis due to incomplete obliteration of the processes vaginalis with the peritoneal cavity. They are very common in preterm and term infants. Generally they do not cause problems but if the processes vaginalis does not close a hernia may occur.

    Testicular torsion is a common cause of acute painful scrotal swelling. If there is inadequate fixation of the testis to the scrotal sac then the testis may rotate (often medially) causing torsion of the spermatic cord with constriction of the vascular supply and subsequent arterial infarction.
    The patients present with sudden onset of pain in the scrotum that may radiate to the abdomen. Nausea and vomiting may occur. The testis often is higher in the scrotal sac than the contralateral testis and there is diffuse testicular and scrotal pain and edema. Erythema or ecchymosis may occur. An absent cremasteric reflex suggests the diagnosis.
    After just a few hours of pain the testis may not be viable.
    Patients may have cycles of torsion and detorsion and thus present with waxing and waning symptoms. Waning pain may also indicate that the testis has already infarcted.

    Urological consultation and scrotal ultrasound with doppler imaging should be performed emergently if suspected. Absent arterial flow in the testicle suggests testicular torsion and emergent surgical treatment should be performed for detorsion and fixation of the testis. The contralateral testis is usually explored and fixated also.
    If surgical treatment is not available in a timely manner, then detorsion can be attempted, after pain relief such as morphine is given. This can be attempted by rotating the long axis of the testis laterally (toward the thigh). Some relief of pain with the testis positioned lower in the scrotum suggests success but the patient should still be evaluated by urology as soon as possible.

    Testicular torsion often occurs in prepubertal children as early as day of life 1. It can also occur in utero. If the torsion occurrs earlier than perinatally, it will often present as a small, firm mass that is fixed to the scrotal skin because the tissue is not viable.
    Testicular torsion that occurs in utero but perinatally may present with a painless scrotal swelling with an enlarged testis secondary to edema that has not resolved yet.

    Learning Point
    Scrotal swelling is a common complaint in the pediatric population that often causes much concern by the patient, family and healthcare provider.
    Painless scrotal swelling generally does not raise as many alarms because benign causes predominate. However it is important to remember that problems such as tumors may present painlessly.

    Painful scrotal swelling or pain in the testis usually raises alarms quickly and boys are brought for evaluation soon after the problem begins.
    While there are benign conditions such as insect bites or rashes that can cause pain, the main concern is for testicular torsion which is a surgical emergency.

    The differential diagnosis of scrotal swelling includes:

    • Painful scrotum, tender testis
      • Epididymitis
      • Orchitis
      • Testicular torsion
      • Trauma – e.g. hematocoele
    • Painful scotum, non-tender testis
      • Incarcerated hernia
      • Insect bite
      • Rash
      • Torsion of testicular appendix
    • Painless scrotum, testis enlarged
      • Genetic syndrome – e.g. Fragile X
      • Testicular torsion in newborn
      • Tumors of the testis – e.g. primary and secondary
    • Painless scrotum, testis normal sized
      • Henoch-Schonlein purpura
      • Hydrocele
      • Incarcerated hernia
      • Scrotal edema – idiopathic or generalized

    Questions for Further Discussion
    1. How does torsion of the testicular appendix present?
    2. What testicular tumors are common in children?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topic: Testicular disorders

    and at Pediatric Common Questions, Quick Answers for this topics: Hydrocele and Hernia.

    To view current news articles on this topic check Google News.

    Fleisher GR, Ludwig S. Synopsis of Pediatric Emergency Medicine. Williams and Wilkins. Baltimore, MD. 1996:197-200.

    Illingworth RS. Common Symptoms of Disease in Children. Blackwell Scientific Publications: Oxford. 1998:329-331.

    Minevich E, Tackett L. Testicular Torsion. eMedicine. Available from the Internet at http://www.emedicine.com/med/topic2780.htm (rev. 7/20/2005, cited 4/10/2006).

    ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.

    7. All medical and invasive procedures considered essential for the area of practice are competency performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    May 15, 2006

  • When Can Babies Use Sunscreen?

    Patient Presentation
    A 4 month-old female came to clinic for her health maintenance examination.
    The pertinent physical exam revealed a healthy child with normal growth parameters.
    The diagnosis of a healthy 4 month old was made and
    as part of the parent education, the physician recommended that her parents keep her covered with clothing, a hat and sunglasses and out of direct sun as much as possible.
    Her parents asked about using sunscreen, and were told that there was controversy over using sunscreen in children under 6 months of age but that it was probably okay to use it on limited places such as the face and back of the hands.
    The physician discussed other anticipatory guidance issues such as appropriate use of a child safety seat, childproofing the home, not putting the baby to bed with a bottle and the importance of talking, singing and playing with the baby and instituting a healthy bedtime routine.

    Discussion
    Ultraviolet radiation is light with a wavelength that is &lt;400 nanometers. It is further divided into UV-A (320-400 nanometers) and UV-B (290-320 nanometers). UV-B is only <0.5% of the sunlight that reaches the earth but is responsible for most of the damage to skin.
    UV-B increases in intensity close to the equator or at high altitudes, and also in the summer and in the midday sun. Common objects also reflect UV-B thereby increasing its intensity such as water, snow, sand or concrete.

    Tanning is a protective response that begins during sun exposure. It is maximized at the end of exposure for acute tanning and at 7-10 days for delayed tanning. Acute tanning does not make new melanin in the skin but delayed tanning does.

    Sun exposure causes vasodilatation and increase in blood volume in the dermis with resultant erythema. A person’s skin reacts to this exposure differently depending on his/her type. The following types are based upon 45-60 minutes of sun exposure after the winter time or with no previous sun exposure.

    • Type I – Always burns easily, never tans
    • Type II – Always burns easily, tans minimally
    • Type III – Burns moderately, tans gradually and uniformly (light brown)
    • Type IV – Burns minimally, always tans well (moderate brown)
    • Type V – Rarely burns, tans profusely (dark brown)
    • Type VI – Never burns, deeply pigmented (black)

    Sun exposure over a long time is important in the development of nonmelanoma skin cancer (e.g. squamous and basal cell carcinoma) which is the most common malignant tumor in the adult population in the United States. It is rare in children and is generally non-fatal.
    Malignant melanoma is related to exposure of large amounts of sunlight that is episodic. Unfortunately the rates of malignant melanoma are increasing. Survival is increased if caught before metastasis has occurred.

    Chemical phototoxicity occurs when a chemical is taken systemically or applied topically and then sun exposure occurs and the person has an adverse cutaneous reaction. This is solely a chemical reaction and not due to the patient’s immune response.
    Photoallergy is an acquired adverse cutaneous reaction that is similar to phototoxicity but occurs because of an antigen-antibody or cell-mediated hypersensitivity. Common agents include sulfonamides, tetracycline, thiazides, and tretinoin.

    Sun exposure chronically without sunscreens results in excessive wrinkles and skin thicknesses changes and weakens the skin’s elasticity.

    Ultraviolet radiation is also absorbed by the eye and children &lt; 10 years old are at an increased risk because of increased transmissibility during these ages. It can contribute to cataracts, pterygium and photodermatitis.
    The immune system is also affected by ultraviolet radiation in laboratory animals.

    Learning Point
    Prevention is important for sun-related problems.
    Avoiding exposure is the best prevention for infants and children. Activity should be done during non-peak times (&lt;10 AM and after 4 PM). Clouds only reduce the ultraviolet radiation by 20-40%. Parents should also be more careful when the child is around snow, sand, concrete or water.

    Clothing is often the simplest and practical means of sun protection. Lightweight, tightly-woven, long-sleeved shirts and pants work well. Hats also are effective. Wet clothing decreases sun protection.
    A hat decreases the UV-B exposure to the eyes by 50%. Sunglasses are recommended if the child will be in the sun long enough to tan or burn. Glasses labeled to block 99-100% of the UV-B spectrum should be chosen.

    Some professional organizations question the use of sunscreens as protective agents, but many other organizations continue to promote sunscreens including the American Academy of Dermatology and American Cancer Society. A SPF (sun protection factor) of 15 or more is recommended including lip protection. SPF-15 filters >92% of the ultraviolet radiation.
    Sunscreens should be used when the child might tan or burn. The sunscreens should be applied BEFORE exposure, i.e. before going outside. Parents need to be reminded to apply the sunscreen as they get ready for their outdoor activity, and not to do it later (e.g. applying sunscreen after they are at the beach.)
    There is no data showing sunscreens prevent melanoma, and tanning prevention may also prevent or delay skin aging and nonmelanoma skin cancer.

    Infants &lt;6 months should be kept out of direct sunlight as they cannot move themselves, have less melanin for protection and are at risk for heat problems and dehydration.
    It is controversial whether or not infants <6 months old should use sunscreen because of their possible risk of different absorption, metabolism and excretion of drugs. The American Academy of Pediatrics states that in addition to avoiding exposure "in situations where the infant's skin is not protected adequately by clothing, it may be reasonable to apply sunscreen to small areas, such as the face and the back of the hands."

    Questions for Further Discussion
    1. Should adolescents and children use tanning beds?
    2. How is SPF (sun protection factor) measured?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topic: Sun Exposure
    and at Pediatric Common Questions, Quick Answers for this topic: Sun Protection.

    To view current news articles on this topic check Google News.

    American Academy of Pediatrics Committee on Environmental Health. Ultraviolet Light: A Hazard to Children. Pediatrics. 1999:104-328-333.

    ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    5. Patients and their families are counseled and educated.
    8. Health care services aimed at preventing health problems or maintaining health are provided.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    Mary 8, 2006