Ocular
Albinism

• Introduction
• Instructions
• About the Author
• Credits
• Accrediting States
• Genetic Influence In Ocular Disorders using Albinism as a Role Model for Study

  1. Oculocutaneous Albinism
  2. Cutaneous Albinism
  3. Ocular Albinism
• Optometric Management
• Acknowledgements
• References
• Multiple Choice Examination
• Additional Marchon Educational Materials
• Answer Sheet

This special issue dealing with genetic disorders of the eye is the first in our series of home-study, continuing education courses for optometrists. If you would like to receive future lessons for CECs or simply for their interest and benefit, we invite you to contact your Marchon sales representative or write directly to Marchon for a free copy.

Ocular albinism is purely and typically genetic in nature. So your investigation of albinism actually serves as prototype for studying and understanding the basic principles behind other inherited eye diseases; for example, glaucoma, macular degeneration, and color-vision deficiency. But our text offers more: In addition to contributing to your understanding of genetic eye diseases in general, our updated material on albinism can be put to use clinically in your everyday optometric practice. This will prove to be especially useful in cases of "hidden" albinism.

Details on how to carry out the multiple-choice examination are spelled out below. Note that, by obtaining a passing grade on the lesson's optional, multiple-choice examination, you will be entitled to two hours of continuing education credits toward your annual State Board relicensing. However, even if you're not looking for CECs and you don't intend to qualify, why not test your knowledge of the subject by taking the Q-and-A test for your own enlightenment and satisfaction?

1. Read and study the text on the following pages.
2. Analyze and study the multiple-choice questions.
3. Circle the answers to the questions on the answer sheet.
4. Clip the completed answer sheet and mail it to: Marchon, Department of Education and Research, 35 Hub Drive, Melville, New York 11747-3500, together with your check in the amount of $24.95 to cover processing costs (applicants who fail the examination may re-take it at no extra charge).

He has published more than 50 papers in all leading optometric journals including those published by the American Academy of Optometry, the American Optometric Association, Review of Optometry, Optica International and others. He has served as chairman of the American Optometric Association's Committee on Publications, president of the Optometric Editors Association, and as NJAO liaison to the New Jersey Academy of Science.

With the exception of those State Boards that do not accept home-study courses or do not require CECs, this lesson has been approved for two hours of continuing education credits (a list of accrediting States is shown below). To earn the credits, you must achieve a grade of 70% or higher on the test. Upon successful completion of the examination, a CEC certificate will be issued to you by Marchon's Department of Education and Research with the completion date stamped on the form. It will be your responsibility to submit the CEC form to your State Board for recognition. Any questions? Phone (800)645-1300 or (516) 755-2020.

AK, AR, AZ, CA, DC, DE, HI, IA, ID, IN, KS, MA, MI, MN, MO, MS, ND, NH, NJ, NM, OH, OR (one hour), PA, RI, SD, WA, WY.

Albinism comprises a group of genetically determined pigmentary disorders in which pigment making cells (melanocytes) are present but, because of an inborn error of metabolism, they cannot form the dark pigment (melanin) that is essential for coloring the hair, skin and/or parts of the eye.

The disorder occurs in varying degrees of hypopigmentation, with total albinism exhibiting easily recognized signs while partially affected cases (as you soon will see) are much more difficult to detect¹

Studies in regard to the prevalence of albinism in one form or another vary greatly, with estimates ranging upwards from one in 2,000 persons (partial albinism)² to one in 16,000 persons in the United States (total albinism)³. But the number of afflicted cases may be much higher since many of these persons may not even realize they have the disorder or they may well be trying to hide the fact⁴.

Wayne W. Hoeft, O.D., classifies albinism into three main groups, as follows⁵: I. Oculocutaneous (total or classic) involving the eyes, hair and skin; II. Cutaneous, (partial or modified); and, III. Ocular (affecting mainly the eyes).

Although our text will concentrate on Group III (ocular albinism), introductory genetic discussions of oculocutaneous and cutaneous albinism are in order and soon will follow.

But before we begin our course, let's review some pertinent definitions relating to genetics since heredity plays such an important role in the study of albinism. As mentioned earlier, an added benefit of this review is that it will be helpful in your diagnoses of other inherited diseases at risk besides albinism. As D. Vaughan astutely put it: "Genetic influences are (now) being described in an increasing number of eye diseases, and a primary causative role for genetic defects is being more clearly defined. Thus," he concludes, "it becomes more important than ever to understand the principles of genetic transmission⁶."

Of course, if you are already well versed in genetic terminology, you may wish to skip over the balance of this section. Be aware, though, that there may be some useful descriptions explained below, so we suggest you skim through them on your way to the main text.

Recall that genetics is a science that studies inherited characteristics as they relate to the composition and function of genes - the basic units of inheritance. An inborn error is a genetically determined biochemical disorder in which defective enzymes produce a metabolic disturbance with often pathological consequences.

Chromosomes are genetic bodies that are passed from parent to offspring. Each human cell has 46 chromosomes, constituting 23 match pairs. One member of each chromosome pair is inherited from the father, the other from the mother. And since a normal sperm and a normal ovum each contain 23 chromosomes, each parent transmits half of the total genetic information to each child.

Of the 23 pairs of chromosomes, 22 pairs are called autosomes (Greek, auto, self, chroma-somes) because the two "partners" of each pair are similar in makeup. Autosomic pairing has no role in determining whether the offspring will be male or female. The remaining pair of chromosomes has dissimilar partners called X and Y chromosomes which, as we soon will see, do play a major role in sex determination.

Genotype refers to the genetic pool of information of a person while phenotype refers to the observed physical, physiologic, or biochemical characteristics. Mutation is the transformation of a gene, often sudden and dramatic (as could happen in radiation, for example, but could have no known cause), into a different gene occupying the same position on the chromosome as the original gene; the new gene being allelic (see alleles, below) to the normal gene from which it has arisen.

Alleles. Genes at a specific location (locus) on each pair of chromosomes can have a variety of forms referred to as alleles (Greek, meaning "reciprocals"). If both members of a pair of alleles are identical, the individual is homozygous. If the paired allelic genes are dissimilar, the person is heterozygous. For example, the gene for blue eye color and the gene for brown eye color are two alleles on the gene for eye color.

Dominance This is the ability of a specific genetic characteristic to appear at the expense of another. When one gene exerts greater influence over its paired allele on the chromosome, it is referred to as being dominant. On the other hand, when a gene is weaker than its allele, it is called recessive.

Disease entities that can be caused by abnormal genes are classified as being (1) autosomal dominant, (2) autosomal recessive, or (3) sex-linked.

(1) Autosomal dominant. As mentioned earlier, when an autosomeÕs allele exerts a stronger influence over its paired allele, it is referred to as being dominant. Therefore, dominant designates a gene whose phenotype effect largely or entirely obscures that of its allele. An autosomal dominant trait is transmitted by an affected person (heterozygote) to an average of 50% of the offspring.

(2) Autosomal recessive. An autosomal recessive disease is expressed, or produced, when each parent carries an abnormal (mutant) gene. Thus, for an offspring to be affected, both parents must pass the defective gene. In this case, an average of 25% of the siblings will be affected. For example, the gene for blue eyes is recessive and will not manifest itself if the gene for brown eyes (which is dominant) is also present; blue eyes will manifest themselves only if both genes are recessive.

(3) Sex-linked. A trait determined by genes carried on either of the X or Y chromosomes is properly termed sex-linked or X-linked. These are the genes that determine the sex of the offspring. What happens is that a male possesses one X and one Y chromosome, so he can pass either an X or a Y chromosome to the offspring. But both of a female's chromosomes are of the X variety (with no Y chromosomes) and, therefore, she can pass on only an X chromosome. It follows, then, that if the offspring inherits and X and a Y chromosome, a male child will be born. On the other hand, if the offspring inherits two X chromosomes, a female child will be born.

X-linked genes can be X-linked dominant or X-linked recessive. In X-linked dominant disorders, females are affected more often than males, and all daughters (no sons) of affected males are affected. In X-linked recessive diseases, the females are carriers (heterozygotes), and only males are affected. All daughters of affected males are carriers.

Genetic counseling determines the risk of a particular genetic disorder occurring within a family and provides information and advice based upon that determination. Genetic screening is designed to detect potential genetic handicaps in parents or their progeny. Amniocentesis is a technique performed in certain genetic settings on pregnant women. This procedure involves making a needle puncture of the uterus through the abdominal wall to allow amniotic fluid and fetal cells to be withdrawn; these then can be subjected to tests for various genetic diseases. However, at the present time, amniocentesis has not been applicable to detect eye disorders. Recently, researchers have been searching for DNA markers that may be linked to some genetic eye diseases in the hope of providing accurate prenatal and genetic counseling.

But counseling entails a keen working knowledge of basic genetic principles and sensitive advisory skills, skills which fall into the realm of genetic counseling practitioners. In your role as a health-care provider, you should be familiar with the science of genetics so that you will not only know to whom the patient should be referred but, also, so that you will be able to discuss the case intelligently with that referred specialist.

So much for the review of genetics. We now proceed to our discussions of our main text; namely, I. OCULOCUTANEOUS ALBINISM, II. CUTANEOUS ALBINISM, and, III. OCULAR ALBINISM, as follows:

This group of persons with oculocutaneous albinism develops the disorder through genetic traits in which both mother and father have normal coloration but each parent carries (often unknowingly) a single albinism gene. That is, they each have a normal gene and an albinism gene and will pass one of these genes when they conceive a child. Thus, they each have a 1 in 2 chance of passing on the albinism gene to their offspring. As a result of each pregnancy, there is a 1 in 4 chance (1/2 x 1/2) that their baby will get two genes for albinism, in which case the offspring will have no normal blueprint for making pigment and, consequently, will be born with albinism⁷.

Oculocutaneous types of albinism exhibit a total lack of pigment, resulting in white hair, brows and lashes and skin color ranging from pale to silky white when compared with others of the same ethnic or racial background. The irises are pale blue in color and are translucent, which renders them able to be totally transilluminated. The fundi are also light pale in color. Vision problems are invariably present. These include moderate-to-severe nystagmus, moderate-to-high astigmatism, photophobia, strabismus, and marked low vision.

Currently, researchers have defined 10-20 different types of oculocutaneous albinism, and four main types of ocular albinism.

The most common types of oculocutaneous albinism are commonly referred to as ty-positive and ty-negative, which stand for tyrosinase-positive and tyrosinase-negative. These terms evolved from a test in which a few hairs are plucked from the scalp of a person with albinism. For this screening test, roots or "bulbs" of the hairs are incubated in a chemical solution of tyrosine - an amino acid or protein building block enzyme used by the body to make melanin pigment. Ty-pos (tyrosinase positive) hair bulbs turn dark in the test, signifying they are making pigment. Ty-neg (tyrosinase negative) hairbulbs do not, indicating they are not making pigment and, therefore, these patients experience more difficulty with vision (V.A. in ty-neg cases vary from 20/25 to 20/400 but is often only about 20/200⁸). Those with ty-pos albinism have slight pigmentation and less severe vision difficulties.

Until a few years ago, unless a person had albinism or had a child with the condition, there was no way of knowing whether he or she carried this gene. Recently, however, a test was developed to identify carriers for the ty-neg type: it measures how fast hairbulbs make pigment. Another new method for prenatal testing can be done by DNA analysis at 9 to 10 weeks of gestation. Hopefully, further research may soon lead to genetic blood testing to predict other types of albinism. These tests will greatly enhance the art of genetic counseling.

Persons with cutaneous, or partial, albinism also develop the disorder through autosomal recessive inheritance. They have the classic signs of oculocutaneous albinism at birth but, because these persons are capable of manufacturing small amounts of tyrosinase produced melanin, the resultant effect is that body pigmentation increases until about age 6. This class of albinism also develops varied skin and iris colors in direct ratio to the amount of melanin that is actually produced.

Caucasians are affected more by the lack of pigment than are dark-skinned persons. Pigmentation of the fundus in cutaneous albinism is near normal, with nystagmus being far less evident and visual intolerance to light being substantially reduced in comparison with the patient having oculocutaneous albinism. Transillumination of the irises is more difficult in cutaneous cases of albinism due to the presence of more pigment, with visual acuity ranging from 20/30 to 20/400. With patients considered to be tyrosinase-positive, skin tanning from the sun's rays is also possible because of the small amounts of melanin present.

It is cutaneous albinism that might well allow a blond patient to attempt to hide his or her problem, or to not even know about it. But your diagnosis and management of the visual aspects of the disorder can, in many instances, greatly benefit that individual.

As mentioned earlier, although types of oculocutaneaous and cutaneous albinism span from 10 to 20 in the minds of investigators, there are actually four major classes of ocular albinism to consider⁹.

Class 1 is the classic type of ocular albinism commonly referred to as X-linked ocular albinism (also called sex-linked ocular albinism, Nettleship Ocular Albinism Nettleship-Falls Ocular Albinism, XOAN, and OA1) where the gene responsible for the disorder is located on the X chromosome.

There are a trio of criteria for X-linked albinism; namely, (1) only males are affected, (2) female carriers transmit the disorder to 50% of their sons, and, (3) father-to-son transmission is impossible. This is because many of the X-chromosome genes are unopposed by a Y chromosome. Abnormalities of these genes cause disease in the male, whereas in the female an abnormal recessive gene of the sex chromosome is masked by its normal allele. Thus, nearly all X-linked diseases are manifested in males, whereas the disorder is passed through females. In other words, when a male and his maternal grandfather are affected, intervening females are carriers¹⁰.

In Class 1 of persons with ocular albinism, the hair color is either normal or slightly decreased in amount in both infants and adults when compared with normal siblings. Visual acuity often ranges from 20/50 to 20/400, with carrier females exhibiting a mosaic retinal pigmentation that is visible ophthalmoscopically.

Class 2 of ocular albinism is a variation of X-linked ocular albinism that includes high-frequency hearing loss sometime between puberty and 40 years of age. However, hair and visual acuity run the same as X-linked albinism. Visual acuity in Class 2 ocular albinism, as in Class 1, also runs from 20/50 to 20/400.

Class 3 of ocular albinism results from an autosomal recessive inheritance affecting males and females equally, with the hair being either normal or slightly lightened. V.A. ranges from 20/100 to 20/400. (With autosomal recessive inheritance, both parents each carry one albinism gene even thought they are virtually unaffected as far as their physical appearances are concerned. This is because a normal dominant gene makes an abnormal allele gene recessive. Disease occurrence is 25% in siblings. But there is a chance the aberrant gene will be modified by the normal gene, making the child a carrier like the parents; thus, he or she will then be phenotypically - but not genotypically - normal¹¹).

Finally, Class 4 is ocular albinism accompanied by excessive skin freckles and sensorineural deafness; that is a hearing loss due to a lesion in the sensory mechanism (cochlea) of the ear, or to a lesion in the acoustic nerve or the central neural pathways, or perhaps to a combination of such lesions. Visual acuity in Class 4 ocular albinism is in the vicinity of 20/200, with the hair being normal. The trait for this type is said to be autosomal dominant.

It is interesting to note that, in all four types of ocular albinism described above, the hairbulb test produces positive results.

(Occasionally, one runs across the term Forsius-Erikkson=Ocular Albinism, also referred to as Aland Island Eye Disease. This condition has been thought to be another variation of ocular albinism featuring high myopia, nystagmus, and night blindness, but it is now more appropriately classified as a form of congenital night blindness which a number of experts feel should be renamed Forsius-Erikkson-Miyake Syndrome¹².)

It has been reported that, with age, the iris color can change from blue to hazel to brown in both the X-linked and autosomal recessive forms¹³.

Although some specialists in ocular albinism say they see no effects in the skin and hair of these patients, at least one study from London notes that if the parents have dark brown hair and olive skin, the ocular albinotic child may well have light brown hair that darkens somewhat with age as well as fair skin that tends to tan¹⁴. The reason for the tanning is that the skin in ocular albinism contains abnormally large melanosomes that contain more tyrosinase capable of helping in synthesizing more melanin.

As with the blond patient with cutaneous albinism, the blond child or adult with ocular albinism should be able to benefit visually from the assistance of a knowledgeable and tactful O.D.

Contrasting an ocular albinism victim with the oculocutaneous type, the former's diluted pigmentation in the eye is more the result of abnormalities in melanosome synthesis, while that of the latter is due to inadequate melanization. However, like the oculocutaneous variety of albinism, uveal pigmentation in ocular types of the disorder can range form extremely hypopigmented to a close-to-normal pigmentation level. The amount of uveal pigmentation developed is directly proportional to the degree of visual functioning. Many ocular and visual disturbances of the two types are also similar. These include some or all of the following: subnormal visual acuity, photophobia, nystagmus, strabismus, significant refractive errors, transillumination of the iris and retina, macular hypoplasia, and a blond fundus with visible choroidal vasculature.

Transillumination of the retina is possible because of insufficient development of the retinal pigment epithelium,(RPE) as well as the poor uveal pigmentation. Thus, the resultant funduscopic appearance of a blond fundus is accompanied by broad areas of hypopigmentation and the highly visible vessel system that furnishes blood to the retina.

Normally, the RPE acts as a sink for incoming light. But with the dysplastic retinal pigment epithelium, illumination scatters freely within the eye, with photophobia being a marked subjective complaint. Moreover, the photophobia is intensified by stray light waves that enter the eye through the hypopigmented irises (Fig. 1). Finally, incomplete development of the macula helps explain the pendulum-like nystagmus as the patient's eyes continually seek out the clearest possible image¹⁵.

Fig. 1 Stray light entering the eye through hypopigmented irises intensifies existing photophobia (courtesy National Organization of Albanism and Hypopigmentation).

According to Dr. Irene Maumenee¹⁶, symptoms such as nystagmus and poor vision are not enough for eyecare practitioners to go on in order to make a definitive diagnosis of albinism. "This pair of symptoms can come with a variety of conditions," advises. "Therefore, you should follow up by shining a light into the pupil to see whether the iris lights up. The translucency shows more of a possibility of some form of albinism".

However, even the above is not complete. J.W. Haefemeyer, et al, write that it's better to look for foveal hypoplasia in the retina as well as hypopigmentation. That, they write, will confirm a suspected diagnosis of ocular albinism¹⁷.

Yet another symptom of ocular albinism is the absence of stereopsis and the presence of tropias which can be traced to the misrouting of nerve pathways from the retina to the brain's visual cortex. What happens in this case is that some fibers from the nasal-temporal border of the retina are shifted 20^o into the temporal retina instead of corresponding with the fovea, as happens in normally pigmented persons (Fig. 2). This was borne out by a modified visually evoked response (VER) study, in which one eye was stimulated at a time to evoke a volley of nerve impulses. A definitive diagnosis of albinism can be drawn from this modified VER procedure, particularly in confusing cases¹⁸.

Unfortunately, there is no cure for albinism - oculocutaneous, cutaneous or ocular - but surgery has been suggested for strabismus in terms of cosmesis and possible improvement in visual fields. Lately, Dr. Thomas D. France found that the use of cyclopentolate in latent nystagmus has reduced the amplitude, velocity of phase, and, to a lesser extend, the frequency of the condition in 6 out of 10 patients he studied¹⁹.

Fig. 2 Note the 20 - degree shift of retinal ganglion fibers from the fovea of an afflicted case as compared with distribution in a normal retina (courtesy Ophthalmic Pediatrics and Genetics, Netherlands).

So the answer to some of the symptoms troubling persons with ocular albinism seems to be astute management by the optometrist, as follows:

Along the above lines, Dr. Hoeft emphasizes the need for a careful low-vision examination. "A complete, concise history along with testing for the proper differential diagnosis is a must," he writes.

Included among his suggestions are health tests, measuring corneal toricity, radical retinoscopy, and control of illumination. In addition, he stresses the need for trial-frame refraction - for both distance and near. Trial-frame refraction is especially important in those cases involving high cylindrical correction close to the axis of the nystagmus. Moreover, Dr. Hoeft adds, trial-frame refraction permits the choice of the precise vertex distance as well as freedom of head and eye movements in nystagmus - a situation that is not the case when a phoropter is used.

Drs. R. Abadi and E. Pascal²⁰ write that, with albinism patients exhibiting high refractive errors, especially high levels of astigmatism, it is essential that the best optical correction be provided, whether it is in the form of eyeglasses or contact lenses. Spectacles have such advantages as they are easier to fit and adapt to, and there are almost no limitations on the availability of cylindrical powers or axes. On the other hand, contact lenses should provide a superior optical system due to their introducing fewer spherical and cylindrical aberrations and ability to induce fewer prismatic imbalances than do eyeglasses.

Theoretically, then, contact lenses should be ideal. But, a study by W.O.G. Taylor found only three out of 55 persons with albinism were able to tolerate their lenses, possibly due to the heightened tactile sensitivity and nystagmus common in this disorder²¹.

An excellent way to help your patients suffering from ocular albinism is to learn all you can about low vision and low-vision aids - both optical and non-optical.

Among the major optical forms of low-vision aids often recommended for persons with any type of albinism are bioptic telescopic spectacles (BTS) with low to moderate adds, or even simple magnifiers. Improvement in both distance and close vision can come from bioptics and mini-telescopes that may be placed conveniently in front of or behind the carrier lens.

Bioptic telescopic spectacles are often a great help to persons with albinism who operate motor vehicles in states that permit BTS driving under certain conditions. These are especially useful to those who live outside urban areas where public transportation is limited.

Manufacturers of bioptic telescopic lenses include: Feinbloom's Designs for Vision (Ronkonkoma, NY, 800/345-4009) and Eschenback Optik (Ridgefield, CT, 203/438-7471). A more complete list of BTS manufacturers is available from AOA's Low Vision Section (see American Optometric Association's Low Vision Section on page 11).

Closed circuit television systems, notably those that magnify printed matter many times (for example, TeleSensory of Mountain View, CA 800/227-8418) plus computers with software for large-character screen displays are electronic low-vision aids that can enhance the albinotic patient's quality of life.

As for sunglasses, Dr. Maumenee reports that albinotic patients often opt not to wear them, complaining that sunwear reduces their already low vision. However, these patients can sometimes be helped by incorporating UV protection in clear or lightly tinted lenses.

In regard to treating youngsters with ocular albinism, Dr. Maumenee advises, "Always talk to the parents and explain what they can expect in the way of visual acuity from that child and whether he or she is capable of succeeding in a conventional school or if it's better to think about a school for the blind or near blind." The choice seems to be in the hands of the parents and the child as well as the optometrist.

As mentioned earlier, an excellent way to help albinotic patients is to learn all you can about low vision. If you're currently not involved in this area, you can begin by contacting the American Optometric Association's Low Vision Section - a division of AOA dedicated to indoctrinating O.D.s in the art and science of low-vision practice²².

AOA's low-vision specialty group provides each new member with Introduction to Low Vision: A Resource Guide for Practitioners. The guide includes a list of resources, a bibliography, and a how-to approach to low-vision care. A semi-annual newsletter updates members on new products and developments in the field, and the Section sponsors an annual continuing educational symposium on low vision during AOA Annual Congresses.

All AOA members are eligible to join the Low Vision Section. To obtain an application, contact the Section office at 314/991-4100, extension 223.

The International Library, Archives and Museum of Optometry (ILAMO) offers a full scope of low-vision materials and information, both for practitioners and patients. In addition to numerous clinical and practice management books on low vision, the library also offers videotapes, audio cassettes and slide sets with scripts for low-vision presentations. For further information, contact ILAMO at 243 N. Lindbergh Blvd., St. Louis, MO 63141, 314/991-4100.

A wide-ranging, five-page, free list of optometric sources for low-vision optical and non-optical aids is available from the American Foundation for the Blind (AFB), which acts as a national clearinghouse for information about blindness and visual impairment. Write the society at 15 W. 16th Street, New York, NY 10011, or phone 212/620-2000, Hotline: 800/AFBLIND. Enclose a self-addressed stamped envelope if you request a copy by mail.

You also should consider purchasing AFBs Visual Impairment: An Overview- a 49-page information booklet and resource directory on low vision for clinicians and lay persons. Published by the American Foundation for the Blind, the booklet's authors are Ian Bailey, O.D., professor of optometry and physiological optics at University of California's School of Optometry, and Amanda Hall, Ph. D., the school's low-vision services coordinator and research specialist. The primer includes; anatomy of the eye, photographs illustrating vision impairments, techniques and devices for low vision, and a comprehensive resource list for the visually impaired and their families. Send $12.95 plus $3 for shipping and handling to the American Foundation for the Blind (see address, above.)

Another guideline for O.D.s is advised by Janice L. Knuth, MSW23, president of the National Association of Albinism and Hypopigmentation and herself a person with albinism to refer patients - whether oculocutaneous, cutaneous or ocular-and their families to organizations that can provide them with social and emotional adjustments that they often require. The Association, generally referred to by its acronym NOAH, offers newsletters and other printed materials. Telephone or in-person counseling, on a one-to-one basis, is also freely available. NOAH's address is: 1500 Locust St., Ste. 1816, Philadelphia, PA 19102, or call toll-free 800/473-2310 (In Pennsylvania, call 215/545-2322). "We have chapters in close to 20 states and contact in some 20 more," the organization president says.

Director Knuth adds still another source by noting services provided by the Council for Citizens with Low Vision, International (5707 Brockton Dr., Ste, 302, Indianapolis, IN 46220). With members in North and South American, Australia, Canada, Japan, and many other countries, this 3,000-member advocacy organization has support groups, large-print newsletters, and a national conference each year in conjunction with the American Council of the Blind's National Conference. The council for Citizens with Low Vision can be contacted at 800/733-2258, or at 317/254-1185 in the Hoosier state. Their FAX number is 317/251-6588.

(Ed. Note: Persons with albinism as well as professionals in the field look upon the term "albino" with disfavor. Much preferred are: "persons with albinism," "pigment-deficient person," and synonyms along these lines).

The author extends his thanks to Dr. Lawrence A. Cone, Chief of Immunology and Infectious Diseases at Eisenhower Medical Center, Rancho Mirage, CA, for his valuable suggestions and review of the text. Thanks are also extended to the International Albinism Center at The University of Minnesota Hospital and Clinic for its helpful referential material, especially for its booklet, "Facts About Albinism." (A copy of the Center's publication is available for a small donation. Address: University of Minnesota Medical School, Division of Genetics and Metabolism, Box 485 UMHC, 420 Delaware St., S.E., Minneapolis, MN 55455.) Thanks also to NOAH, the National Association for Albinism and Hypopigmentation, for sending lucid pamphlets on the subject. (These, too, are available. Just forward a modest donation to the Association whose address appears in the left-hand column of this page). Finally, our thanks go to Richard Barnett for assisting in our search of the literature. Mr. Barnett is copy editor of Patient Care - a medical journal for primary-care physicians.

1. Maumenee, I, Telephone interview, August 1991.
2. Haefemeyer JW, Knuth, JL, "Albinism," Jrnl. Ophth, Nurs. & Tech., 1991. 10; (2): 55, 62.
3. Ibid, 2.
4. Ibid, 2.
5. Hoeft WH, "Albinism - A clinician's low vision perspective," Jrnl. AOA 1991; (1) 69-72.
6. Vaughan D, Asbury T, General Ophth. 11th Ed., 1986, Lange Med. Publ., Los Altos, CA, 318-323.
7. Haefemeyer, JW, King RA, LeRoy, B. "Facts About Albinism," Int. Alb. Ctr., U. Of Minn. Hosp, Clin., 1989:344.
8. Haefemeyer, JW, "What Is Albinism?," NOAH Info. Bull., Nat. Organiz. Albinism & Hypopigmentation, Undated, 88;6:88.
9. Ibid, 5.
10. Ibid, 5.
11. Ibid, 6.
12. Weleber RG et al, "Aland Island Eye Disease (Forsius-Erikkson Syndrome associated with contiguous deletion syndrome at XP. Similarity to incomplete congenital night blindness." Arch. Ophth., 1989; 107: (8) 1170-1179.
13. King RA, Summers CG, "Albinism," Dermato. Clin. 1988; 6: 212728.
14. Russell-Eggitt I, Kriss, A, Taylor, DSI, "Albinism in childhood: a flash VEP and ERG study." Brit. Jrnl. Ophth., 1990;74:(3)136140.
15. Sowka JW, Gurwood AS, "Low vision rehabilitation of the albino patient," Jrnl. AOA,1991;62:(7)533536.
16. Ibid, 1.
17. Ibid, 2.
18. Ibid, 3.
19. France, TD, "Noninvasive Methods Making Inroads in Nystagmus Treatment," quoted in Ophth. Times, June 15, 1991, p. 16.
20. Abadi R, Pascal E., "Recognition and management of Albinism," Ophth. Physiol. Optom,.1989;9:(1)3-19.
21. Taylor, OG, "Aiding the Vision in Albinism, Optical and Non-Optical means considered," Trans. Ophth. Soc., 1985; 104:(3)309-314.
22. Anan, BS, "Low Vision," Optom. Econ., 1991;1:(8)30-35.
23. Knuth JL, "Services and How to Find Them," NOAH Information Bulletin, undated, 887-888.

1. Body pigmentation increases in cutaneous albinism until age: a. ten b. six c. eight d. twenty	2. One variety of sex-linked ocular albinism features a hearing loss that takes place between: a. birth and puberty. b. birth and age 40. c. puberty and age 40. d. age 5 through age 40.
3. In ocular albinism, the _________ vasculature is highly visible in a blond fundus. a. uveal. b. scleral. c. corneal. d. choroidal.	4. If two "X" chromosomes are inherited the result will be: a. a male offspring. b. twins. c. an albinotic child. d. a female.
5. Carrier females of classic ocular albinism exhibit: a. white skin. b. mild nystagmus. c. mosaic retinal pigmentation. d. none of the above.	6. Symptoms of ocular albinism include all except: a. opaque irises. b. nystagmus. c. night blindness. d. photophobia.
7. In autosomal recessive ocular albinism and X-linked ocular albinism, iris color has been known to change from ________to _______ to _______ with age. a. blue to hazel to brown. b. pink to red brown. c. pale blue to dark blue. d. pink to red to blue.	8. White hair, white eyebrows and white skin are symptoms of: a. oculocutaneous albinism. b. cutaneous albinism. c. ocular albinism. d. none of the above.
9. Which of the following is not a criterion for X-linked recessive inheritance? a. there is no father-to-son transmission. b. carrier females transmit the disease to one-half of their sons and one-half of their daughters. c. males alone are affected. d. X-chromosome genes are opposed by a Y-chromosome.	10. In autosomal recessive inheritance, disease occurrence in children is in a ratio of: a. one to four. b. two to four. c. three to four. d. four to four.
11. Circle True (T) or False (F): a. Ty-pos hairbulbs turn light in color when incubated in a solution of tyrosine. (T) (F). b. Ty-neg persons have more severe vision difficulties than ty-pos persons. (T) (F). c. Tyrosine is an enzyme used by the body to make melanin. (T) (F). d. Ty-pos and ty-neg are terms employed in the definition of oculocutaenous albinism. (T) (F).	12. In ocular albinism, decreased eye pigmentation may best be traced to: a. inadequate melanization. b. foveal hypoplasia. c. photophobia. d. abnormal melansome synthesis.
13. In autosomal recessive inheritance, there is a _______ chance that the normal gene will modify the affected gene. a. 1 in 3. b. 1 in 4. c. 1 in 2. d. zero.	14. Inadequate development of the macula can help explain: a. blond fundus. b. strabismus. c. photophobia. d. nystagmus.
15. Low-vision examination in albinism might well include: a. corneal toricity testing. b. radical retinoscopy. c. a complete patient history. d. all of the above.	16. A spectacle lens holding a low-vision aid, such as a mini-telescope, would be called the _______ lens. a. carrier. b. telescopic. c. primary. d. magnification.
17. In addition to albinism a knowledge of genetics is useful in the diagnosis of: a. glaucoma. b. macular degeneration. c. color-vision deficiency. d. all of the above.	18. _______ is necessary for biosynthezing melanin in pigment cells. a. Thymosin. b. Neutrophil. c. Cuprimyxin. d. Tyrosinase.
19. In X-linked ocular albinism, uncorrected visual acuity usually runs from: a. 20/50 to 20/300. b. 20/50 to 20/400. c. 20/100 to 20/400. d. 20/200 to 20/400.	20. The absence of stereopsis in ocular albinism can be traced to a shift of _______ degrees into the temporal retina instead of corresponding with fovea: a. 5 degrees. b. 10 degrees. c. 15 degrees. d. 20 degrees.
21. Circle True (T) or False (F): a. A gene that exerts greater influence over its paired allele is referred to as being dominant. (T) (F). b. A dominant gene designates a gene whose phenotype effect obscures that of its paired allele.(T) (F). c. When both members of a pair of alleles are identical, the individual is heterzygous. (T) (F). d. When both members of a pair of alleles are dissimilar, the individual is homozygous. (T) (F).

ABO. No. 102.
Modern Ophthalmic Frame Materials - discusses the relationship between modern frame materials and the occupational/avocational needs of customers.

ABO. No. 103.
Dispensing Eyewear to Children - kids are among the most difficult age-groups to fit comfortably with eyewear. The text explains how to solve problems associated with fitting and adjusting eyewear to youngsters.

ABO. No. 104.
A Hands-On Review of Basic Ophthalmic Lens Parameters - a comprehensive study of eyeglass lenses for beginners in the field and also as a review for experienced ophthalmic personnel.

OD No. 104.
Optometric Management of Age-Related Skin Changes of the Eyelids and surrounding tissues - the lesson offers a number of suggestions on how to correct and/or camouflage skin defects that affect patients entering middle and old-age.