Optic pathway glioma (OPG), seen in 15% to 20% of individuals with neurofibromatosis type 1 (NF1), account for significant morbidity in young children with NF1. Overwhelmingly a tumor of children younger than 7 years, OPG may present in individuals with NF1 at any age. Although many OPG may remain indolent and never cause signs or symptoms, others lead to vision loss, proptosis, or precocious puberty. Because the natural history and treatment of NF1-associated OPG is different from that of sporadic OPG in individuals without NF1, a task force composed of basic scientists and clinical researchers was assembled in 1997 to propose a set of guidelines for the diagnosis and management of NF1-associated OPG. This new review highlights advances in our understanding of the pathophysiology and clinical behavior of these tumors made over the last 10 years. Controversies in both the diagnosis and management of these tumors are examined. Finally, specific evidence-based recommendations are proposed for clinicians caring for children with NF1.

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Optic pathway gliomas in neurofibromatosis-1: Controversies and recommendations

PURPOSE For the past 25 years, the WHO Programme for the Prevention of Blindness and Deafness has maintained a Global Data Bank on visual impairment with the purpose of storing the available epidemiological data on blindness and low vision. The Data Bank has now been updated to include studies conducted since the last update in 1994. METHODS An extensive literature search was conducted in international and national scientific and medical journals to identify epidemiological studies that fulfilled basic criteria for inclusion in the Data Bank, namely a clearly stated definition of blindness and low vision, and prevalence rates derived from population-based surveys. Sources such as National Prevention of Blindness Programmes, academic institutions or WHO country or regional reports were also investigated. RESULTS Two-hundred-and-eight population-based studies on visual impairment for 68 countries are reported in detail, providing an up-to-date, comprehensive compilation of the available information on visua...

2002 global update of available data on visual impairment: a compilation of population-based prevalence studies.

Risk Factors for Age-related Macular Degeneration

Amblyopia characterization, treatment, and prophylaxis.

Preschool vision screening : Rationale, methodology and outcome

Aims: In order to establish normal values and interocular differences of visual acuity, Lea symbols were applied to neurologically and ophthalmologically normal children. Methods: 385 children (21–93 months old) were examined, within a routine check up in an urban paediatric practice where Lea symbol acuity (LS) was measured. Of these children, 90 were re-examined in hospital comparing Lea symbol acuity (LS) and Landolt C acuity (LC). Strabismus, ametropia, and any organic eye disease were excluded. Results: In the paediatric practice, LS could be measured on both eyes in 54% of the children. In the age group above 36 and 48 months the success rate was 76% and 95%, respectively. Acuity in the paediatric practice ranged from 0.1 to 2.0 (median 1.25) in the whole group. Interocular acuity difference was one line or less in 80%. In the hospital, LS and LC could be measured on both eyes of 77% and 48% of the 90 children, respectively. Cooperation increased with age. LS in the hospital ranged from 0.32 to 2.0 (median 1.0) and LC from 0.16 to 1.25 (median 0.8). Interocular difference of LS acuity was one line or less in 90%. Conclusion: Lea symbols were found to be useful for visual acuity assessment in early childhood. Significant variability of visual acuity in this age group is caused by cooperation. When monocular measurements are possible on both eyes, however, the intraindividual interocular difference of visual acuity usually does not exceed one line.

https://bjo.bmj.com/content/bjophthalmol/86/5/513.full.pdf

Examination of young children with Lea symbols

· Objective: Lea symbols can be used for measuring visual acuity in childhood. Therefore, these symbols might be useful for early detection of amblyopia. We evaluated whether the visual acuity determined with Lea symbols (LS) corresponds to the visual acuity determined with the Landolt-C (LC). · Patients and methods: In 55 strabismic amblyopic volunteers aged 5–59 years, the monocular visual acuity of both eyes was determined using LC and LS. For comparison, the right eye of 20 healthy volunteers was examined. Single optotypes (LC, LS) were used in 55 amblyopes and crowded optotypes (LC17.2, LC2.6, CLS) in 40 amblyopes. The luminance of the test charts was 180–200 cd/m2, with a contrast >85%. The refraction of the subjects was corrected beforehand. · Results: In the 40 amblyopic eyes tested under each condition, LS exceeded CLS and LC by about 1 line (dB), LC17.2 by 2 lines and LC2.6 by 3 lines (mean values ± SD: LS 0.62±1.8 dB, CLS 0.46±1.7 dB, LC 0.5±2.0 dB, LC17.2 0.41±2.3 dB, LC2.6 0.29±2.3 dB). The non-amblyopic fellow eyes and healthy eyes showed smaller differences (fellow eyes LS 1.32±1.1 dB, CLS 1.17±1.1 dB, LC 1.15±0.9 dB, LC17.2 1.05±0.9 dB, LC2.6 0.93±1.1 dB; healthy eyes LS 1.74±0.9 dB, CLS 1.58±0.8 dB, LC 1.48±0.6 dB, LC17.2 1.41±0.7 dB, LC2.6 1.32±1.1 dB). In the amblyopic eyes, the reduction of LC was more distinct than the reduction of LS. Fifty-two amblyopes had an amblyopia >1 dB of LC, LC17.2 and LC2.6, while 50 had an interocular acuity difference >1 dB CLS. · Conclusions: Using Lea symbols, a recognition acuity can be determined and amblyopia can reliably be detected. Due to their design, the Lea symbols are particularly suitable and recommendable for application in young children. However a slight systematic difference between LS and LC has to be considered.

Lea symbols: visual acuity assessment and detection of amblyopia.

Background: Screening for amblyogenic factors in infancy by pediatricians is unsatisfactory, as they hardly ever detect ametropia or microstrabismus. As photoscreening seems to be a helpful method to detect even small squint angles and refractive errors, we tested the MTI photoscreener for its sensitivity with respect to amblyogenic factors. · Patients and methods: One hundred and twelve children aged 6–48 months were first examined with the MTI photoscreener. Then each child underwent complete medical examination by an ophthalmologist and an orthoptist. The examination included the Hirschberg test (corneal reflex evaluation), the Bruckner test (fundus red reflex), and, where possible, the Lang stereotest, the cover test and visual acuity assessment, as well as a motility test, biomicroscopy, ophthalmoscopy in mydriasis and refractometry in cycloplegia. Exclusion criteria were any organic pathological results, manifest strabismus, ametropia ≥2 D and astigmatism ≥1 D. An orthoptist, a pediatrician and two ophthalmologists independently evaluated the Polaroid pictures according to the criteria given in the handbook of the MTI photoscreener. · Results: For 10 children the evaluation with the MTI photoscreener was not possible despite the fact that photographs were retaken several times. Thirteen photographs showing obvious pathologic findings despite their poor quality were included. Eighty-three of the remaining 102 children failed the eye examination according to the above-mentioned criteria. The mean sensitivity of the MTI photoscreener was determined to be 82.8%. The ability to correctly identify the absence of any amblyogenic factors (specificity) was 61.8%. · Conclusions: Sensitivity was high when compared to the usually low detection rate during pediatric examinations. Due to the low specificity, effectiveness was poor. Therefore an ophthalmological examination should be included in the preventive screening during infancy and early childhood.

Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood.

Purpose: An abnormal head posture adopted to reduce a nystagmus can be treated by Kestenbaum surgery or by creating an exodeviation which is compensated by convergence (artificial divergence). We evaluated the effects of Kestenbaum surgery and artificial divergence surgery in a retrospective study. Methods: Seventy-eight patients who received surgery for horizontal head turn (HT) due to nystagmus were included in the study. Exclusion criteria were previous extraocular muscle surgery, strabismus, lack of binocular vision, and cerebral disease. The millimetres of surgery and the findings before and 3 months after operation [HT, binocular visual acuity (VA), binocular vision (BV)] were evaluated. The patients were divided into three groups: the Kestenbaum group, the artificial divergence group, and the artificial divergence plus Kestenbaum group. Results: Of the 78 patients, aged 3–68 years, 52 had HT to the left side and 47 were male. In the Kestenbaum group (n=31), the median (10% and 90% quantile) HT was 30° (range 20–40°). A total of 28 mm (range 20–40 mm) surgery reduced the HT to 10° (0–30°). The efficacy of surgery was 1.4° HT reduction per millimetre surgery on one eye (range 0.4–2.5°). Four patients received further surgery. In the artificial divergence group (n=27), 10 mm (range 7–12 mm) surgery reduced the HT of 30° (range 25–40°) to 5° (range 0–20°). Seven patients received further surgery. In the artificial divergence plus Kestenbaum group (n=20), the HT was 30° (range 25–40°). A total of 29 mm (range 21–37 mm) surgery reduced the HT to 7° (range –5° to 15°). No further surgery was performed. Postoperatively, the maximum VA and BV was available without large HT, but an increase in the absolute VA and BV could not be proved. Conclusion: Artificial divergence is preferable or should be combined with Kestenbaum surgery, if possible. Kestenbaum surgery alone has an effect/dose ratio similar to recess-resect surgery for strabismus. Thus, to correct x° HT, 2/3x mm surgery on each eye is adequate.

Surgery for nystagmus related head turn: Kestenbaum procedure and artificial divergence.

Objective To describe a visual acuity test for use in identifying psychogenic visual impairment and malingering. Methods The test contained 32 white plates with a black Landolt C printed in the center. The sequence of the 4 alternative directions of the C was not predictable. After plate 21, 4 circles were interspersed among the remaining plates. The test is administered at a distance from which the subject is presumed to be able to recognize the optotypes. He or she is requested to identify the direction of the C within 2 seconds, and the responses are noted. Two elements were evaluated: (1) The number of correct answers was compared with the corresponding value of the distribution function of the binomial formula that represents the probability of reaching this rate of correct answers by pure chance. (2) The response to the first circle (appearing after plate 21) was compared with the responses to the previous 19 Cs. The test was administered to 20 volunteer pseudomalingerers and 15 patients believed to be true malingerers. Results Malingering was detected in 14 (74%) of 19 volunteers included in the evaluation and in 12 (80%) of 15 patients by too many or too few correct answers to the stimuli or by their response to one of the circles. Conclusions This test is useful in proving malingering. It may also provide evidence of a minimum visual recognition acuity within the gross dimension of the actual acuity.

https://jamanetwork.com/journals/jamaophthalmology/articlepdf/270900/ecs10250.pdf

Michael Gräf

Papers

Examination of young children with Lea symbols

Lea symbols: visual acuity assessment and detection of amblyopia.

Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood.

Surgery for nystagmus related head turn: Kestenbaum procedure and artificial divergence.

Ocular Malingering: A Surprising Visual Acuity Test