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CLINICAL APPLICATIONS

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Manual of Instructions for Testing Heterophoria and Prism Divergence at Near 1947 This report is an instruction manual for testing heterophoria, a condi- tion in which the eyes have a constant tendency to deviate but are prevented from so doing by fusion. When a person looks at an object, an image of that object Is formed separately in both the right and the left eye. These separate images are sent to the brain, where they are associated and in- terpreted as a single unage; this process is known as fusion. Fusion is responsible for the two eyes working together in harmony; when anything prevents this, fusion is disrupted and one eye deviates. For the purpose of heterophona measurement, fusion can be disrupted by placing a Maddox rod in front of one eye. The image of a spot of light, when viewed through a Maddox rod, is converted into a line of light. When the two eyes see unlike images of the same object (one eye sees a spot of light while the other eye, the one behind the Maddox rod, sees a line of light), this disrupts fusion and tends to prevent the two eyes from working together. Thus, when heterophoria is present, the eye behind the Maddox rod will deviate while the other eye continues to look at or fixate the spot of light. The measurement of heterophoria is one of the more difficult problems that the experienced examiner can meet, because many factors can influence the test and only a few of these are actually known. Unless the test is performed in exactly the same way at every testing station, an examinee may pass the test at one station on one day and fail it on the next day at another station. A uniformly standardized testing technique must be used at every station. This manual describes the testing technique to be followed at all testing stations. Descriptions of apparatus and procedures are given for testing het- erophoria and prism divergence with the binocular photometer, with the portable monocular photometer, and with trial frame and loose prisms. 7 pp. 2 figures no tables no references Availability: Committee on Vision, 2101 Constitution Ave., N.W., ~sh- ington, D.C. 20418. 17

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Manual of Instructions for Clinical Testing of Visual Acuity 1947 (revised 1951) Visual defects are one of the major causes for physical disqualification from the Armed Services of the United States. Methods of testing vision have varied greats among the services and from place to place in each service; as a consequence, visual test results are not comparable. A can- didate presenting himself or herself for examination at one center might be qualified for visual acuity, while at another center he or she would be disqualified. The purpose of the manual is to descn~e the conditions and facilities necessary and the procedure to be followed in order to correct this situation. The procedures outlined in the manual should be followed by every person who administers visual tests. It is the duty of the Medical Officer- in-Charge to supervise and inspect the proper administration of procedures outlined in this manual. The manual describes procedures to be followed in testing visual acuity with wall charts. It is understood that the use of optical instruments may become sufficiently general at some future date to warrant a revision of the manual Exact specifications of the test chart, the test room reflectances and illumination, and occluders are given The procedures for administering the test are described in detail, including phrases to be used in instructing the examinee. Scoring procedures are described in full. 19 pp. 11 figures no tables no references Availability: Committee on Vision, 2101 Constitution Ave., N.W., Washington, D.C. 20418. 18

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Report on International Nomenclature for Designating Visual Acuity Kenneth N. Ogle 1953 The task of the subcommittee that produced this report was to obtain a majority point of view regarding a proposal to standardize (1) a partic- ular mode of designating visual acuity and (2) a particular graduation of steps in letter size for the visual acuity charts. These two problems are interdependent and involve a number of fundamental problems. Many ophthalmologists have insisted that the visual acuity test charts are primarily for clinical use (1) to determine the effect of certain ocular diseases on visual acuity and (2) especially to assist in the determination of the refractive correction for patients. Visual acuity itself is not important until the final refractive correction is approached in the refraction examina- tion. The exact manner in which the letters of successive lines of the chart decrease in size would for this purpose be relatively less important. The majority of the members of this committee, however, felt that the design of test charts be such that reasonably accurate determinations of visual acuity itself could be made. A uniform decimal scale or fractional designation of visual acuity requires some type of a uniform graduation in the sizes of the letters of successive lines of the test chart. There seems to be almost universal agreement that this graduation should approach that of a geometrical progression, that is, a graduation in which the size of the letters of one line bears a constant ratio to the size of the letters in the preceding (or succeeding) line of the chart. Such a method of preparing a visual acuity chart gives sizes of test letters of successive lines on the chart, which increase in a geometric progression. Instead of making all the letters on a given line of the chart the same size, it may be desirable to design the test chart so that successive letters increase in size. The subcommittee made a number of recommendations on the basis of the discussion and of the considerations presented in the report. 15 pp. 3 figures 1 table 23 references Availability: Committee on Vision, 2101 Constitution Ave., N.W., ~sh- ington, D.C. 20418. 19

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Manual of Instructions: Armed Forces Vision Tester 1951 (revised 1952) This report is a manual of instructions for the Armed Forces Vision Aster. The Vision Tester is an instrument that may be used to test certain visual functions of near and far viewing distances. One person is tested at a time with one instrument. The examinee observes a series of test slides, some of which test distance vision, others near vision. The examiner asks standard questions while the emminee is observing each slide and determines the instrument score from the answers to these questions. The visual functions examined in the standard form of the tester are vertical and lateral phoria at distance and near, right and left eye acuity at distance and near, and depth perception at distance. A special test of distance acuity is available for testing illiterate examinees. It is also possible to test binocular acuity at distance and near and prism divergence at near. These special tests are described in the report 24 pp. 2 figures no tables no references Availability: Committee on Vision, 2101 Constitution Ave., N.W., Wash- ington, D.C. 20418. 20

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First Interprofessional Standard for Visual Field Testing 1975 This report contains a review of basic data and concepts for mea- surement of visual held and makes the following recommendations: (1) photometric standards for visual field test equipment should be expressed in luminance units; and that the illuminant and its desired operating charac- teristics be specified by the manufacturer for each visual field testing device; (2) in the specification of chromatic stimuli, the wavelength composition of the stimulus reaching the eye and the C.I.E. (Commission International de l'Eclairage) chromacity coordinates should be given; (3) background field luminance, test target parameters [target luminance, size (area), configura- tion, and exposure duration or rate of translation], viewing distance, and location of a target in the visual field should be specificable; and (4) office, field, and screening instrument design should incorporate test parameters that produce relatively stable response states. 35 pp. 14 figures 3 tables 74 references Availability: AD 637389, National Technical Information Service ~S), 5285 Port Royal Road, Springfield, VA 22161. 21

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Recommended Standard Procedures for the Clinical Measurement and Specification of Visual Acuity 1980 The primary objective of this report is to formulate test conditions, procedures, and criteria that can serve the clinical need associated with routine ophthalmological and optometric measurement of visual acuity. The aim is to enable different examiners to obtain the same test results. The major emphasis is on the standardization of so-called distance acuity for distances approximating optical infinity. Recommendations are also made for tests at a suggested near distance of 40 cm (16 inches). The proposed near tests include (a) measures of acuity with capital letters under conditions comparable to those used to measure distance acuity and (b) tests of ability to read continuous text. 45 pp. 21 figures 4 tables 28 references Availability: Advances in Ophthalmology VoL 41, pp. 103-148, 1980. 22

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Clinical Applications of Visual Psychophysics Luis M. Proenza, Jay M. Enoch, and Arthur Jampolsky, Editors 1981 The Committee on Vision held a symposium in October 1978 on applications of psychophysics to clinical problems, in conjunction with the Second Study Group on Human Vision. The revised and edited proceedings of this symposium constitute this volume. Three problem areas were selected for consideration: the utilization of recently developed contrast sensitivity, the assessment and development of vision in infants, and localization of anomalies in the visual pathway. A concluding chapter summarizes the current very active state of the boundary between basic and clinical visual science. 304 pp. 235 figures 4 tables 312 references Availability: New York: Cambridge University Press, 1981. 23

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Nutrition, Pharmacology, and Vision: Proceedings of a Symposium John E. Dowling, Luis M. Proenza, and Constance W. Atwell, Editors 1982 In November 1981 the Committee on Vision held a symposium on nu- trition, pharmacology, and vision. The revised and edited papers presented at this symposium constitute this report Nutritional research has identified some 45 substances as essential to our diet (National Academy of Sciences, Science and Technology, a Five- Year Outlook, W.H. Freeman & Company, 1981~; however the full range of cellular and tissue functions in which these essential nutritional substances participate is not known, and it is likely that additional research will identifier yet other substances as also essential nutrients. Knowledge concerning the role of some of these essential substances has increased enormously within the last decade, particularly with regard to neuronal and visual functions. It is along this new frontier of adding functional pharmacologic insight to basic structural knowledge that this symposium was directed. The following papers were presented at the symposium: "Some As- pects of Vitamin A Malnutrition," J.~ Olson; "Nutrition and Retinal Degeneration," E.L. Berson; "Selective Loss of 11-CIS Vitamin A in an Eye With Hereditary Chorioretinal Degeneration Similar to Sector Retinitis Pigmentosa," C.D.B. Bridges and R.~N Alverez; "Is Taurine an Essen- tial Amono Acid?" N. Lake; "The Rules of Vitamin E and Unsaturated Fatly Acids in the Visual Process," W.G. Robison, Jr., et al.; "Choline Metabolism and the Maintenance of Photoreceptor Cell Structure," R.H. Masland; "Nutritional Amblyopia," D.L. Knox et al.; "Changes in Retinal Morphology and Vitamin A Metabolism as a Consequence of Decreased Zinc Availability," NE. Leure-Dupree and C.D.B. Bridges; "Nutritional Factors and Dark Adaptation," R.M. Russell; "Neurotransmitter Systems in the Retina," B. Ehinger; "Function of Neurotransmitters in the Retina," N.W. Daw et al.; "The Effects of 13rrosine and Other Nutrients on Neu- rotransmitter Synthesis in the Brain and Retina," C.J. Gibson et al.; "The Ib~c Effects of Glutamate and Related Compounds in the Retina and the Brain," ].W. Olney; and "Pharmacologic Control of Cortical Plasticity," J.D. Pettigrew. 144 pp. 39 figures 4 tables 397 references Availability: The Retina VoL 2, No. 4, pp. 231-375, 1982. 24

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Myopia: Prevalence and Progression 1989 In this report the findings of research published since the early 1800s on the progression and prevalence of myopia (nearsightedness) are analyzed. Myopia is the visual condition in which only nearby objects appear in focus, much like a camera permanently focused at a close distance. In a "normal" or emmetropic eye, distant objects are naturally in focus, like a camera focused at infinity. Prevalence estimates from the 1972 National Health and Nutrition Examination Survey of persons in the United States between the ages of 12 and 54 years indicate that 25 percent were myopic. Individual differences are also known to occur in the progression of myopia. Ophthalmic clinicians widely acknowledge that, once a youngster becomes myopic, he or she will most likely become more myopic, and this increase in myopia will stop or slow down sometime in the teenage years or later. There is, however, a great deal of individual variability in the age at which progression ceases. An extensive literature review was conducted. Over 500 articles were identified, the majority of which had been published in the last 40 years in English-language journals. A significant number of articles in nineteenth- century periodicals were also identified. In addition to the literature search, a limited number of published research findings in languages other than English were identified. 113 pp. 11 figures 24 tables 266 references Availability: Distribution Service, National Academy Press, 2101 Consti- tution Ave., N.W., Washington, D.C. 20418. 25

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Considerations in Contact Lens Use Under Adverse Conditions: Proceedings of a Symposiums Pamela Ebert Flattau, Editor 1990 Contact lenses are an alternative method to spectacles for correcting refractive error. Soft lenses are more comfortable and adaptation is so rapid that intermittent wear is practical. Disadvantages are fragility, cost, and inability to correct more than minimal astigmatism without modifications. Contact lenses are often fitted for cosmetic purposes. Contact lenses also offer an important alternative, however, to the restrictions presented by spectacles for engaging in certain activities - such as athletics or working in steamy or rainy atmospheres. Furthermore, in certain occupations, contact lenses made it possible to use equipment that would otherwise be incompatible with spectacle frames (headgear in firefighting equipment is just one example). Concerns persist, about the effects of such adverse conditions as: low humidity, low oxygen, environmental irritants (gas, smoke, dust), and tissue inflammation on contact lens wear. A working group was established by the Committee on Vision familiar with the scientific, clinical, and technological aspects of contact lens use, with special emphasis on their use under adverse conditions. This report is the proceedings of a symposium organized by the working group held in San Antonio, Texas, on November 3 and 4, 1988, to describe current concerns regarding lenses to the military community (see Contact Lens Use Under Adverse Conditions: Applications in Solitary Aviation). Approve: 176 pp. 48 figures 11 tables 257 references Availability: National Academy Press, 2101 Constitution Ave., N.W. Wash- ington, D.C. 20418. 26

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Contact Lens Use Under Adverse Conditions: Applications in Military Aviation . 1990 In response to a formal request from the ltise~vice Aeromedical Research Panel (TARP), the Committee on Vision formed a working group to summarize current scientific, clinical, and technological issues in the use of contact lenses and to review the operational requirements of military personnel to the use of contact lenses under adverse conditions. These conditions are understood to challenge the integrity of the cornea and include the following effects: (1) hypomc effects (oxygen deprivation), (2) mechanical effects (cornea! shape changes), (3) biochemicalIbiophysical effects (dry eye syndrome, corneal swelling, epithelial insult, etc.), and (3) infection and inflammation (bacterial, viral, fungal, allergies, etc.~. This report identifies the critical factors to be taken into account by the military services in adopting a formal position on the use of contact lenses by U.S. military personnel (see Considerations us Contact Liens Use Under Adverse Conditions: Proceeding' of a Symposium). 44 pp. no figures no tables 40 references Availabdity: Publication on Demand, National Academy Press, 2101 Con- stitution Ave., N.W., Washington, D.C. 20418. 27

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