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Significance This study explains the construction and validation of a chart in Hindi language, one of the commonly spoken languages in the world. The new visual acuity chart is called LEA Hindi chart. The calligraphy construction method described here can help develop other such acuity charts. Purpose The purpose of this study was to construct and validate a new logMAR Hindi visual acuity chart (LEA Hindi chart) using principles similar to that of LEA symbols acuity chart. Methods A multicenter (three centers) study was conducted in two phases. The first phase consisted of identifying and constructing the Hindi optotypes using calligraphy techniques. The Hindi optotypes were calibrated against the Landolt C optotypes by measuring the threshold distance for visual acuity. In the second phase, the newly constructed LEA Hindi chart was validated against the Early Treatment Diabetic Retinopathy Study (ETDRS) and Landolt C visual acuity charts. Sixty participants were enrolled for the first phase (centers 1 and 2) and for the second phase of the study (centers 1 and 3). Additional 15 participants were enrolled (center 1) for testing repeatability. Results Four Hindi optotypes were identified and used for the construction of the chart (first phase). In the second phase, the LEA Hindi chart was found to be comparable with both the Landolt C, (logMAR acuity difference, 0.03 ± 0.13; P > .18) and ETDRS (logMAR acuity difference, -0.02 ± 0.09; P > .25) charts. All the three charts were also found to be repeatable (95% limits of agreement within 0.24 logMAR). Conclusions The newly constructed LEA Hindi visual acuity chart gave comparable levels of visual acuity as that measured in an ETDRS or Landolt C charts. The repeatability was also similar to the standard charts. The LEA Hindi visual acuity chart can be used for patients comfortable with Hindi language and also in studies requiring multiple measurements of visual acuity, to avoid familiarity to a given chart.

Assessment of visual processing disorders and their effect on children’s needs for special education is built on observations by parents, teachers and therapists of student’s strengths and problems. Visual problems at school should guide the medical specialists, psychologists and optometrists in assessment of visual functions. Ophthalmologists’ and optometrists’ work in assessments of binocularity, strabismus, oculomotor functions and accommodation is now developing; spectacles to correct refractive errors can be fitted in comfortable frames, training of visual functions is included in rehabilitation and reported to schools. Interdisciplinary collaboration between these large groups of educational and medical specialists should be developed further.

Background/Aims There is an increasing recognition that visuocognitive difficulties occur in children with neurodevelopmental problems. We obtained normative data for the performance of primary school children using three tests of visuocognitive function that are practicable in a clinical setting. Methods We tested 214 children aged between 4 and 11 years without known developmental problems, using tests to assess (1) orientation recognition and adaptive movement (postbox task), (2) object recognition (rectangles task) and (3) spatial integration (contours task). Results 96% could do the postbox task with ease—only 4% (all aged 99% of children aged ≥6 years had no, or minor, difficulties. Median scores for the contours task improved with age, and after age 8 years, 99% could see the contour using long-range spatial integration rather than density. Conclusions These different aspects of children’s visuocognitive performance were testable in a field setting. The data provide a benchmark by which to judge performance of children with neurodevelopmental problems and may be useful in assessment with a view to providing effective supportive strategies for children whose visuocognitive skills are lower than the expectation for their age.

Purpose To describe the immediate response to correction of refractive errors and hypoaccommodation in children with congenital Zika syndrome (CZS). Methods Children born between May and December 2015 with a confirmed diagnosis of CZS and enrolled in a multidisciplinary early intervention program were included in this study. All children received a comprehensive ophthalmic examination, including dynamic retinoscopy and cycloplegic refraction. Children were prescribed their full correction if they met the criteria for refractive error, and additional plus 3.00 overcorrection for strabismus, accommodative dysfunction, and/or low vision. Monocular and binocular visual responses to Lea Grating Test at 30 cm, with and without eyeglasses, were measured on day 1 of glasses wear. Results A total of 60 children were evaluated (mean age at evaluation, 11.5 ± 1.1 months; range, 9.0-16.0 months). Lea Grating Test responses were abnormal in all children prior to spectacle correction. Hypoaccommodation was present in 17 of 21 children (81%). Overcorrection was prescribed for all children. Visual responses were subnormal even with glasses use; however, immediate improvement in binocular vision was found in 37 children (62%) and in 74 of 119 eyes (62.2%). For the monocular visual improvement, 27 of 115 eyes (23.5%) had structural abnormalities, and 44 of 115 eyes (38.3%) were structurally normal. There was a statistical difference between the cycloplegic refraction of the children in August and in November, including emmetropia (P = 0.001), hyperopia (P = 0.000), myopia (P = 0.007), and astigmatism (P = 0.004). Conclusions Eyeglasses can improve visual acuity in children with CZS. Significant changes in their refractive status over time requires periodic updates.

Der Beitrag beschreibt die Physiologie der Sehbahnen und das visuelle Profil als Bausteine der Sehuberprufung. Die Dokumentation der Sehuberprufung erhalt eine feste Struktur, wenn sie der anatomisch-physiologischen Ordnung der Phanomene folgt und auch die Fragestellungen der Mitarbeiterinnen und Mitarbeiter sowohl in der Fruhforderung und den Schulen als auch in den Krankenhausern beachtet. „Cerebral bedingte Sehbeeintrachtigung“ („CVI“, Cerebral visual impairment) ist keine Diagnose, nur eine Mahnung, das Kind grundlich zu untersuchen. Die vielen Symptome und Verhaltensweisen der Kinder mit Sehschadigungen erfordern eine Strukturierung der Beobachtungen und der Testsituationen mithilfe der Liste der visuellen Funktionen. Die padagogisch-medizinische Zusammenarbeit erfordert eine gemeinsame Sprache, die wir mit dem Profil der Visuellen Funktionen erreichen konnen. Sie hilft auch, die Informationen zwischen den Teams strukturiert auszutauschen.

To report on the development of the Profile of Visual Functioning as a framework for information exchange between schools and medical specialists involved in the education or care of children with impaired vision due to brain damage.The role of vision loss in a child's functioning can be in part assessed by medical services, but in order to meet the needs of early intervention and education, numerous activities and tasks need to be observed during therapies, early intervention activities, and at local and special schools.Information on vision loss can be gathered effectively and shared between medicine and education using well-structured lists of the most important functions, the Profile of Visual Functioning. We describe a common type of list of vision-related functions and activities.Cooperation between education and medicine requires development of a common language and agreements on how the large amount of information is collected. A basic list of measurements and observations covers functions of most children and thus gives a firm structure to the information exchange.Lists of functions to be examined and activities to be observed, if used by all stakeholders, may improve the quality of assessments for early intervention and special education. At the same time, schools and hospitals need to jointly arrange further education so that the names of activities start to make sense to doctors and the medical terms to teachers.

A summary of the visual pathways in the brain is presented as a basis for considering abnormalities in this system. The role of the cortical associative regions in visual function is briefly delineated. A short summary of experiments describing plastic properties of the visual pathways at early age is also presented, and experiments describing neural and behavioural changes after binocular deprivation are reviewed. It is concluded that early visual deprivation leads to a profound alteration of the associative systems of the brain and that in monkeys and humans these changes are difficult to remedy later. Therefore early detection and correction of visual abnormalities is very important as well as early compensation using other forms of sensory communication.

Visual system transfers information at both high and low contrastlevels. It has been customary to assess visual function by measuring visual acuity although it has been well documented for over ten years' time that measurement of contrast sensitivity may reveal loss of visual function that is not detected by measurement of visual acuity. There are several commercially available clinical tests that are used in Scandinavian countries for assessment of visual transfer function in low contrast domain. We have chosen six of them for comparison: Cambridge Low Contrast Gratings, Vistech's contrast sensitivity tests for distance and near, PelliaRobson's low contrast letter chart, Vistest's LH-5 contrast visual acuity test, and Mentor's computer based device for measurement of both contrast sensitivity and low contrast visual acuity. Each of the commercial tests measures low contrast vision in slightly different way. In order to have an overview of the function of these tests we have assessed vision of visually impaired patients and normally sighted subjects using all tests during one visit. In general the grating tests result inslightly higher contrast sensitivity values than the optotype tests. Contrast sensitivity values measured with grating tests are difficult to assess because the size of the stimulus affects the values. Based on our results, we recommend assessment of low contrast visual transfer using an optotype test as the basic test and a grating test in order to assess vision for orientation and mobility. The grating test should be used at two different distances resulting in approximately two and ten degree stimuli.

The results of this selected group of glaucoma patients demonstrate that the effect of glaucoma on the contrast sensitivity can be assessed only after careful exclusion of all other causes for decrease in contrast sensitivity. Further development of methods is necessary.

Indocyanine green (ICG) fluorescence angiography has been further refined for use in both laboratory and clinical investigations. In the present modification of the Zeiss fundus camera all lenses except the aspherical objective lens have been specially antireflection coated to increase light transmission in the spectral region around 800 nm. A 300 watt indium iodide lamp continuous light source has replaced the conventional xenon flash lamp. This light source produces a retinal irradiance of 265 mw, and therefore restricts retinal exposure time to 11.9 seconds, but that time is more than adequate to record passage of dye through the choroid. Spatial resolution of the fundus on the film has been increased from 11.7 microns to 7.4 microns. With these technical refinements the choroidal circulation can be studied at 20 frames per second, which is adequate to document the very rapid movement of blood through the vasculature. ICG angiography may change our interpretations of choroidal circulatory phenomena which are now based on fluorescein angiography, and it clearly is an effective tool in laboratory (experimental) investigations.

Spatial contrast sensitivity of 19 diabetics with different degrees of visual impairment was studied. It was found that contrast sensitivity at intermediate and low spatial frequencies may decrease without corresponding loss of visual acuity. In advanced cases of diabetes the opposite may be true: contrast sensitivity was better than expected on the basis of visual acuity. Thus both visual acuity and contrast sensitivity measurements are useful in the evaluation of the nature of visual impairment due to diabetic eye disease.

A new test chart was developed for the measurement of visual acuity of pre-school children. The symbols of the test are circle, square, apple and house. These were so designed that each symbol measures visual acuity similarly. This feature of the test was verified experimentally. The visual acuity values measured by the individual symbols correlated highly with the visual acuity values measured with the whole test (0.82-0.86). The correlation between the visual acuity values measured repeatedly, the reliability of the new test, was found to be 0.94 for adult subjects. The new visual acuity test thus fulfils the statistical criteria of a good visual acuity test. Because both children and nurses seem to like the new test, it may be useful in the assessment of visual acuity in pre-school children.

26 males and 13 female carriers of different ages with choroideremia of varying severity were investigated using sodium fluorescein (FAG) and/or indocyanine green (ICG) fluorescence angiography. Females with minor changes present in pigment epithelium may stay unchanged throughout life or gradually develop into a more advanced stage resembling the fundus picture of severely affected males. In moderately affected females there is a patchy degeneration of pigment epithelium in the macula. Peripapillary degeneration is seen also in indocyanine green fluorescence angiograms. In males, atrophic areas and the remaining choriocapillaris are clearly demonstrated in FAG and less well visible in ICG angiograms. ICG angiograms show choroidal vessels more clearly in cases where the pigment epithelium and the choriocapillaris are still present. In advanced cases in males and females, the choroidal blood circulation is slow.

Visual processing disorders are a common hidden problem of children with a more visible disability, which is considered to be the primary disability even if it may affect the development and learni...

Visual assessment of deaf persons presents a challenge to the ophthalmologist and the optometrist. At the time they want to measure visual function, the interpreter uses visual communication, competing for the patient's attention. Important rules of good assessment of visual functioning include taking turns and giving the interpreter sufficient time to convey the questions related to each test. This has implications for audiologists working with this population as well. Communication should be tailored to the varying needs of people who may have long-standing deafness and good sign language, may have lost their hearing at an advanced age and have limited or no sign language, or may be young persons or children who have congenital or progressive loss of hearing combined with congenital or progressive vision loss. Individuals with sudden hearing and vision loss, as well as those with intellectual disabilities and limited language, are particularly challenging groups for the assessment of vision and require special communication skills for ophthalmologists and audiologists. The ophthalmologist usually knows the nature of vision changes typical of disorders that the patient has. For the clinical follow-up of a condition, a few measurements are usually taken. For a comprehensive assessment of visual functioning for rehabilitation and education, many more measurements, observations, and questions are needed so that vision for communication, orientation in the environment, and performance of near-vision tasks can be reported and the effects of the environment can be evaluated. Testing should cover ocular disorders and vision loss caused by brain damage.

Background: Patients with homonymous hemianopia often have some residual sensitivity for visual stimuli in their blind hemifield. Previous imaging studies suggest an important role for extrastriate cortical areas in such residual vision, but results of training to improve vision in patients with hemianopia are conflicting. Objective: To show that intensive training with flicker stimulation in the chronic stage of stroke can reorganise visual cortices of an adult patient. Methods: A 61-year-old patient with homonymous hemianopia was trained with flicker stimulation, starting 22 months after stroke. Changes in functioning during training were documented with magnetoencephalography, and the cortical organisation after training was examined with functional magnetic resonance imaging (fMRI). Results: Both imaging methods showed that, after training, visual information from both hemifields was processed mainly in the intact hemisphere. The fMRI mapping results showed the representations of both the blind and the normal hemifield in the same set of cortical areas in the intact hemisphere, more specifically in the visual motion-sensitive area V5, in a region around the superior temporal sulcus and in retinotopic visual areas V1 (primary visual cortex), V2, V3 and V3a. Conclusions: Intensive training of a blind hemifield can induce cortical reorganisation in an adult patient, and this case shows an ipsilateral representation of the trained visual hemifield in several cortical areas, including the primary visual cortex.

Background: Blindness of a visual half-field (hemianopia) is a common symptom after postchiasmatic cerebral lesions. Although hemianopia severely limits activities of daily life, current clinical practice comprises no training of visual functions in the blind hemifield. Objective: To find out whether flicker sensitivity in the blind hemifield can be improved with intensive training, and whether training with flicker stimulation can evoke changes in cortical responsiveness. Methods: Two men with homonymous hemianopia participated in the experiments. They trained with flicker stimuli at 30° or with flickering letters at 10° eccentricity twice a week for a year, and continued training with more peripheral stimuli thereafter. Neuromagnetic responses were registered at 1–2-month intervals, and the Goldmann perimetry was recorded before, during and after training. Results: Flicker sensitivity in the blind hemifield improved to the level of the intact hemifield within 30° eccentricity in one participant and 20° eccentricity in the other. Flickering letters were recognised equally at 10° eccentricity in the blind and intact hemifields. Improvement spread from the stimulated horizontal meridian to the whole hemianopic field within 30°. Before training, neuromagnetic recordings showed no signal above the noise level in the hemianopic side. During training, evoked fields emerged in both participants. No changes were found in the Goldmann perimetry. Discussion: Results show that sensitivity to flicker could be fully restored in the stimulated region, that improvement in sensitivity spreads to the surrounding neuronal networks, and that, during training, accompanying changes occurred in the neuromagnetic fields.

Aims: To develop standardised texts for assessing reading speed during repeated measurements and across languages for normal subjects and low vision patients. Methods: 10 texts were designed by linguistic experts in English, Finnish, French, and German. The texts were at the level of a sixth grade reading material (reading ages 10–12 years) and were matched for length (830 (plus or minus 2) characters) and syntactic complexity, according to the syntactic prediction locality theory of Gibson. 100 normally sighted native speaking volunteers aged 18–35 years (25 per language) read each text aloud in randomised order. The newly designed text battery was then applied to test the reading performance of 100 normally sighted native speaking volunteers aged 60–85 years (25 per language). Results: Reading speed was not significantly different with at least seven texts in all four languages. The maximum reading speed difference between texts, in the same language was 6.8% (Finnish). Average reading speeds (SD) in characters per minute are, for the young observer group: English 1234 (147), Finnish 1263 (142), French 1214 (152), German 1126 (105). The group of older readers showed statistically significant lower average reading speeds: English 951 (97), Finnish 1014 (179), French 1131 (160), German 934 (117). Conclusion: The authors have developed a set of standardised, homogeneous, and comparable texts in four European languages (English, Finnish, French, German). These texts will be a valuable tool for measuring reading speed in international studies in the field of reading and low vision research.

Twenty percent of visual impairment in children is caused by brain damage. Children with brain damage related visual impairment (CVI) should be assessed in infancy and during their preschool and school age for detection of deviations from normal development of cognitive visual functions at the times these functions should normally emerge. During the last 20 years, treatment of ophthalmologic diseases has advanced greatly. A similar development has occurred in the knowledge of functioning of visually impaired children and assessment of impaired vision. However, early intervention and assessment for special education for children with CVI have not been taught by the leading teaching centres and thus paediatric vision (re)habilitation is lacking behind other areas of ophthalmology and optometry. The groups of children with motor problems, auditory processing problems, intellectual deficiencies of varying severity, who are at high risk of having CVI, are well-known but routine assessment of vision of these children is not a part of vision screening. With some further education of all paediatric services, a change in attitudes toward CVI and minor changes in routine vision services this poorly served fifth of visually impaired children could get adequate treatment, early intervention and rehabilitation.

‘Low vision’ has an international classification as an impairment of vision that is defined by loss of visual acuity and the size of the visual field. Functional classification that would depict capability to use vision in different activities has not yet been agreed upon. Abnormal visual information leads to changes in visual perception, and brain-damage-related visual impairment may alter or prevent one or several cognitive visual functions. Abnormal visual perception opens a window into brain mechanisms that the psychophysicists otherwise do not have. Together with clinicians, psychophysicists can help visually impaired persons to understand the nature of their disability by thoroughly studying the nature of the altered image and the profile of cognitive visual functions.

The aim of the study is to evaluate the Macular Mapping Test (MM-Test) as a simple, quick and cheap screening tool for assessment of AMD and to compare the results with those from automatic threshold perimetry.

Habilitation of infants and children with visual impairments should be based on a thorough understanding of their visual capabilities and limitations. Comprehensive evaluation of visual function includes measurement of visual acuity, contrast sensitivity, visual field, color vision, adaptation, visual sphere, accommodation, and oculomotor functions. It is best completed through a team approach that uses therapists, special educators, and physicians. A complete evaluation also includes examination of the effect of other motor functions on the use of vision. Nearly all aspects of a child’s vision can be measured in play situations with tests that are easy to use. However, further education of nonphysician team members in refractive errors, optics, and function of optical devices may be necessary to ensure an accurate and thorough evaluation.

Background Patients with early age-related maculopathy (ARM) do not necessarily show obvious morphological signs or functional impairment. Many have good visual acuity, yet complain of decreased visual performance. The aim of this study was to investigate the aging effects on performance of parafoveal letter recognition at reduced contrast, and defects caused by early ARM and normal fellow eyes of patients with unilateral age-related macular degeneration (nfAMD). Methods Testing of the central visual field (8° radius) was performed by the Macular Mapping Test (MMT) using recognition of letters in 40 parafoveal target locations at four contrast levels (5, 10, 25 and 100%). Effects of aging were investigated in 64 healthy subjects aged 23 to 76 years (CTRL). In addition, 39 eyes (minimum visual acuity of 0.63;20/30) from 39 patients with either no visible signs of ARM, while the fellow eye had advanced age-related macular degeneration (nfAMD; n=12), or early signs of ARM (eARM; n=27) were examined. Performance was expressed summarily as a “field score” (FS). Results Performance in the MMT begins to decline linearly with age in normal subjects from the age of 50 and 54 years on, at 5% and 10% contrast respectively. The differentiation between patients and CTRLs was enhanced if FS at 5% was analyzed along with FS at 10% contrast. In 8/12 patients from group nfAMD and in 18/27 from group eARM, the FS was statistically significantly lower than in the CTRL group in at least one of the lower contrast levels. Conclusion Using parafoveal test locations, a recognition task and diminished contrast increases the chance of early detection of functional defects due to eARM or nfAMD and can differentiate them from those due to aging alone.

Normal visual functioning is related to cognitive, motor, and emotional development since typical children learn to use visual communication, to move, to talk, and to develop many activities they observe others using. Early detection of atypical visual functioning, particularly in the 1 st year of life can help avoid potentially life-threatening conditions and delays in development which may follow. This article discusses five visual developmental milestones during the 1 st year of life in a typical healthy infant. It also advocates using these milestones in a multidisciplinary approach to early intervention, which includes training of pediatricians and other stakeholders in contact with infants at every level. In addition to this, the development of a cadre of ophthalmic counselors to improve compliance and follow-up may be a cost-effective strategy for pediatric vision care in the developing countries today.

Although residual vision in patients with cortical blindness is common, its brain mechanisms are poorly known. To study these mechanisms we measured neuromagnetic responses to visual stimuli in a patient with right posterior cerebral lesion and left visual field hemianopia. His vision had partially recovered with intensive training before our measurements. Compared with the processing in the healthy side, early occipital responses were attenuated for both passive viewing of checkerboard reversal patterns and a letter identification task. In both conditions there were prominent longer-latency responses at the right superior temporal cortex. We suggest that the activation in the superior temporal cortex can partially compensate for the failure to produce synchronized population responses at the early stages of visual cortical processing.

Die Untersuchung der mehrfachbehinderten, sehgeschadigten Kinder ist auserst wichtig, da auch geringe Sehreste die Fruhentwicklung des Kindes effektiv stutzen. In der Untersuchung mus man mehrere Faktoren beachten: die Entwicklungsstufe des Kindes; die Effekte der Krankheit, speziell die der kurzen Anfalle, der Medikamente und der Korperlage auf die Leistingsfahigkeit des Kindes; die Kommunikationschwierigkeiten und Motivations- und Aufmerksamkeitsprobleme. Die medizinische Untersuchung ist die Grundlage fur die spezialpadagogische und physiotherapeutische Fruhbetreuung, wahrend deren weitere Observationen des Sehvermogens gemacht werden. Eine genaue Analyse fordert oft mehrere Monate Zeit, viele Observationen und eine gute Zusammenarbeit zwischen den padagogischen, den therapeutischen und den medizinischen Teilnehmern des Habilitationsteam.

PURPOSE. To develop a simple and clinically useful technique for observing fixation at an extrafoveal locus (preferred retinal locus [PRL]) with different targets and texts in age-related macular degeneration (AMD). METHODS. A standard slit lamp was modified by adding several fixation targets in the illumination pathway for direct observation and documentation of fixation during fundus examination. Fixation patterns were analyzed in 30 subjects with AMD. RESULTS. The location and stability of fixation with various stimuli was possible to record in each subject. In 23 subjects, there was no difference between the fixations at star and wagon wheel stimuli; in seven subjects, they were in clearly different retinal locations. Fixation was unstable in three subjects. The PRL for reading words was detectable in all subjects. CONCLUSIONS. The present assessment technique seems to offer a simple, clinically available technique to record fixation patterns to different targets and texts.

In Finland the public health authorities recommend that a child's visual development should be checked four times during the first year of life, then once a year. During the first year attention is...

In the care of visually impaired children Early identification of the impairment is important so that Early medical treatment can be started. However, in many cases of congenital or early visual impairment there is no medical or surgical treatment available to improve the quality of vision. These infants, as well as those receiving treatments, are all in need of Early habilitation, both general and specific visual habilitation.

Spatial contrast sensitivity functions of 11 retinitis pigmentosa patients were studied. The patients represented 3 different stages of the disease: 1: in the very severely impaired patients the contrast sensitivity and grating resolution had decreased to a fraction of normal. 2: in severely impaired patients, who had lost peripheral field but had subjectively satisfactory vision in the central field, contrast sensitivity differed considerably from one patient to another, 3: some of the moderately impaired patients, who still had useful peripheral vision, had nearly normal contrast sensitivity in the central vision while they already had large ring scotomas. The severity of reduction in contrast sensitivity was poorly correlated with visual acuity, the size of the visual field and the age of the patient. Because contrast sensitivity function cannot be predicted by means of other clinical measurements, it should be included in evaluation of visual impairment due to retinitis pigmentosa. We also measured contrast sensitivity at low luminance levels: this procedure provided useful information for evaluation of vision in retinitis pigmentosa. The contrast sensitivity function of each patient agreed with the subjective view of the patient about his visual impairment and it also corresponded with the examiners' evaluation of the patient's performance in different visual and visuomotor tasks.

The current understanding of what infants see varies greatly among healthcare and education specialists. Even among ophthalmologists and pediatric neurologists in charge of clinical examinations of infants, opinions vary on what infants perceive, recognize, and use for communication and learning. It is, therefore, of interest to review publications from several specialties to learn whether new information is available on the development of visual functions and use of vision. Ten percent of total publications on this subject are reviewed here based on the usefulness of their content for improving early diagnosis and intervention of vision disorders in infants. Electronic supplementary material The online version of this article (doi:10.1007/s40135-014-0056-2) contains supplementary material, which is available to authorized users.

A 23-year-old woman, blinded at an early age due to retinopathy of prematurity and cataract was successfully operated. After the operation the patient was behaviourally blind. Visual rehabilitation was started 9 months later and lasted 1 1/2 years. During this time the visual behaviour of the patient improved. Quantitative tests were designed to depict the progress. The functional improvement of the patient is in agreement with the findings of animal studies; binocular deprivation during the critical period of development causes behavioural blindness, which is partially recoverable. The result of this study indicates that the visual rehabilitation facilitates the process of recovery. The progress in visual behaviour is likely to reflect an improvement of the function of the associative systems of the brain.

Vision screening of the 3½–4 year olds at the children’s health care centres has long traditions in all Nordic countries (Kaivonen and Koskenoja 1963, Kohler and Stigmar 1973, 1978). In Finland vision screening of pre-school children is included in the assessment of development at 3–4 years of age and at 5½–6 years of age. It should include all children but in big cities, like Helsinki, it covers only 70–80% of children. Vision screening of the preverbal children is more effective because more than 90% of all infants attend to their regular visits at the health care centres during their first year of life.

Vision is a learned function in the normally sighted individuals and in the visually impaired children as well. A visually impaired infant must build his visual concepts based on defective visual information. He must learn to perform smooth tracking movements, saccadic movements and to accommodate and to converge. All these motor functions are needed to achieve the clearest possible image on the retina and to permit fusion in the brain of the images on both retinas.

Early long lasting binocular deprivation results in behavioural blindness in both man and experimental animals. However, few reported cases show that visual rehabilitation may improve visual behaviour. A 34-year-old man who had experienced 30 years of binocular deprivation due to bilateral cataracts received visual rehabilitation for one year. The rehabilitation included training in eye-hand co-ordination, recognition of objects, evaluation of distance and size, and mobility training. Despite signs of recovery of visual functions the patient never started to use vision in his normal life. The negative outcome of the rehabilitation is partly attributed to the patient's motivational problems and to the relatively short rehabilitation time. Visual rehabilitation may be successful when started immediately after the corrective operation on the eyes when the level of motivation is also high.