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PubMed1996

Retinopathy of prematurity.

Retinopathy of prematurity (ROP) is a disease characterized by abnormal growth of retinal blood vessels in the eyes of premature infants. It is especially severe in the tiniest, most premature infants, whose chances of survival have increased with advances in neonatal care. Infants in whom ROP is diagnosed during the perinatal period are at risk for ocular abnormalities and for deficits in visual function. This article reviews the classification of ROP, summarizes current recommendations for screening of ROP in the perinatal period, and describes recent findings with respect to ocular and visual acuity outcomes of infants with ROP.

Child, Preschool↗
PubMed1999

Genetic disorders of vision revealed by a behavioral screen of 400 essential loci in zebrafish.

We examined optokinetic and optomotor responses of 450 zebrafish mutants, which were isolated previously based on defects in organ formation, tissue patterning, pigmentation, axon guidance, or other visible phenotypes. These strains carry single point mutations in >400 essential loci. We asked which fraction of the mutants develop blindness or other types of impairments specific to the visual system. Twelve mutants failed to respond in either one or both of our assays. Subsequent histological and electroretinographic analysis revealed unique deficits at various stages of the visual pathway, including lens degeneration (bumper), melanin deficiency (sandy), lack of ganglion cells (lakritz), ipsilateral misrouting of axons (belladonna), optic-nerve disorganization (grumpy and sleepy), inner nuclear layer or outer plexiform layer malfunction (noir, dropje, and possibly steifftier), and disruption of retinotectal impulse activity (macho and blumenkohl). Surprisingly, mutants with abnormally large or small eyes or severe wiring defects frequently exhibit no discernible behavioral deficits. In addition, we identified 13 blind mutants that display outer-retina dystrophy, making this syndrome the single-most common cause of inherited blindness in zebrafish. Our screen showed that a significant fraction (approximately 5%) of the essential loci also participate in visual functions but did not reveal any systematic genetic linkage to particular morphological traits. The mutations uncovered by our behavioral assays provide distinct entry points for the study of visual pathways and set the stage for a genetic dissection of vertebrate vision.

Albinism↗
PubMed2002

Amblyopia treatment outcomes after screening before or at age 3 years: follow up from randomised trial.

OBJECTIVE: To assess the effectiveness of early treatment for amblyopia in children. DESIGN: Follow up of outcomes of treatment for amblyopia in a randomised controlled trial comparing intensive orthoptic screening at 8, 12, 18, 25, 31, and 37 months (intensive group) with orthoptic screening at 37 months only (control group). SETTING: Avon, southwest England. PARTICIPANTS: 3490 children who were part of a birth cohort study. MAIN OUTCOME MEASURES: Prevalence of amblyopia and visual acuity of the worse seeing eye at 7.5 years of age. RESULTS: Amblyopia at 7.5 years was less prevalent in the intensive group than in the control group (0.6% v 1.8%; P=0.02). Mean visual acuities in the worse seeing eye were better for children who had been treated for amblyopia in the intensive group than for similar children in the control group (0.15 v 0.26 LogMAR units; P<0.001). A higher proportion of the children who were treated for amblyopia had been seen in a hospital eye clinic before 3 years of age in the intensive group than in the control group (48% v 13%; P=0.0002). CONCLUSIONS: The intensive screening protocol was associated with better acuity in the amblyopic eye and a lower prevalence of amblyopia at 7.5 years of age, in comparison with screening at 37 months only. These data support the hypothesis that early treatment for amblyopia leads to a better outcome than later treatment and may act as a stimulus for research into feasible screening programmes.

Age Factors↗
PubMed2002

Screening for amblyopia and strabismus with the Lang II stereo card.

PURPOSE: To evaluate the effectiveness of the Lang II stereo card as a screening test for amblyopia and/or strabismus. METHODS: A total of 1046 children aged 12-13 years were examined in a field study in the Göteborg area, Sweden. In addition to the Lang II stereo card, the examination included visual acuity, cover testing, cycloplegic refraction, and inspection of the optical media and posterior pole. RESULTS: If every incorrect subject response was considered a reason for referral, the Lang II test would have correctly identified 82% (23 subjects) of the 28 children with manifest strabismus and 38% (11 subjects) of the 29 children with amblyopia. The test failed to refer 45% (21 subjects). Of all subjects referred, 44 (63%) were found to be ophthalmologically normal. CONCLUSIONS: The Lang II stereo card is neither a reliable nor an efficient method of screening for amblyopia and/or strabismus.

Adolescent↗
PubMed1996

[Can we identify risk groups for the development of amblyopia and strabismus?].

In the nordic countries 2 to 4% of the population squint and 3 to 5% develop amblyopia. Identification of these children can be done through a general visual screening at a proper age or by selective screening of high risk groups. Several risk factors can be identified: heredity, failure to emmetropize and high hyperopia at the age of 1 year.

Amblyopia↗
PubMed1990

Incidence of open-angle glaucoma and screening of the intraocular pressure with a non-contact tonometer.

New equipment for measuring intraocular pressure have been introduced lately. One of these is the Keeler Pulsair non-contact tonometer which uses pressurized air in measurement. It is found to be safe and easy to use in practice, but it seems to give 1.5-2.0 mmHg lower reading than the Goldmann applanation tonometer. This was confirmed by the present study, where non-contact tonometry was controlled by applanation tonometry with a 2-3 week delay between the measurements. However, for screening procedures the accuracy of the apparatus can be considered as sufficient.

Aged↗
PubMed1995

Is community screening for amblyopia possible, or appropriate?

Photoscreeners are becoming increasingly available and are being widely used to screen for visual abnormalities in young children. However, consideration of accepted criteria for screening programs indicates there is still much further research that needs to be carried out before amblyopia screening could be recommended as a routine component of a community health surveillance program--an adequate description of the potential consequences of an individual developing amblyopia has yet to be provided and the natural history of the condition and factors that determine the effectiveness of treatment have yet to be fully described. While there is the promise of technology that satisfies specific test requirements, this still needs to be trialed in community settings and community trials are required before it will be possible to determine whether the costs that will be incurred in carrying out routine screening and in providing the resources for treatment are warranted. In conclusion, the development of new and possibly more effective technology for screening is only part of the answer to the amblyopia question. While superficially this technology makes screening for amblyopia a possibility, we do not know at this stage whether or not it is appropriate.

Amblyopia↗
PubMed1990

Risk factors in amblyopia.

Any intervention to prevent serious amblyopia is based on the knowledge about normal versus subnormal visual development. Our ability to predict with high degree of certainty which children will develop amblyopia will be dependent on the characteristics of various risk factors for initiating the development of squint or amblyopia. We have used longitudinal studies of population based cohorts of young children to define some of these risk factors such as refractive errors. Three hundred and ten children with an astigmatism greater than or equal to 1.0 D at one year of age were refracted yearly between the age one and four years. Astigmatism and anisometropia were found to be highly variable during infancy and early childhood. Longitudinal follow-up seems to be needed to separate the normal from the abnormal refraction development, which initiates the development of the amblyopia. Children with constant or increasing astigmatism or anisometropia between one and four years were 'at risk'. In parallel we have studied important factors for successful treatment of amblyopia. Based on these findings we conclude that a population screening at four years of age seems to be advantageous in Sweden in order detect and successfully treat most cases of amblyopia.

Age Factors↗
PubMed1995

Longitudinal change of refractive error in infants during the first year of life.

Using cycloplegia, the change in ametropia of 113 infants was followed at 3 month intervals over the first year of life. Scatterplots of the spherical equivalent power show that the dioptric differences exhibit a significant myopic shift of -0.38 ds between 26 and 36 weeks and -0.38 ds between 36 and 52 weeks. The spread of the dioptric differences (95% CI) does not appear to be related to the magnitude of the ametropia present and decreases with time. By 12 months of age the frequency distribution of the spherical equivalent appears to become leptokurtic as it is in the adult. On average the astigmatism was of low degree (less than 1 dioptre cylinder) and with the rule. Anisometropia was rarely seen. The results of this longitudinal study point to an optimal time for screening and perhaps prescribing for 'abnormal' refractive error between 9 and 12 months of age.

Aging↗
PubMedDate not supplied

Ophthalmic screening of school children in Ankara.

Ophthalmic screening was done on 23,810 children visited at schools in different regions of Ankara. Children with below normal visual acuity were invited to the outpatient department and had a full routine ocular examination. Thirty-nine nursery and primary schools were selected, ten of them private, eleven average state schools, seven good state schools and eleven village schools. Among the 23,810 children, 3095 (13%) had various pathology; 1516 were girls, 1579 boys. Refractive errors were found in 85% of the children (2630). This equals 11% of the total screened population. Refractive errors were myopia 32%, hypermetropia 21%, astigmatism 47%. Strabismic children were 2.5%, and amblyopia was found in 1.1%. The purpose of the study was to assess the place of an ocular screening program in primary school children and to discuss the differences encountered in different urban areas.

Age Distribution↗
PubMedDate not supplied

A nurse-led approach to diabetic retinal screening.

Diabetic retinopathy is the leading cause of blindness in people under the age of 60 in industrialised countries (NICE, 2002). This article discusses a nurse-led approach to diabetic retinal screening currently being undertaken at the Western Eye Hospital, London.

Clinical Protocols↗
PubMed1991

Ophthalmologic screening of adults with mental retardation.

Ophthalmological screening was conducted on 113 clients in a work activity center for adults with mental retardation. Thirty-two percent had abnormalities that were neither refractive nor strabismic. We encountered no instance of neglect of current organic ocular disease. However, 37% of clients had at least one eye that either was not within one diopter of emmetropia or that was not corrected to within one diopter of their retinoscopic findings. Ophthalmologists should consider providing screenings in settings familiar to such clients, where they are more likely to be cooperative.

Adult↗
PubMedDate not supplied

Workload management in an outpatient ophthalmology clinic.

1. An RVU system can forecast staffing needs for a busy ambulatory ophthalmology clinic. 2. The average amount of time needed for basic ophthalmic screening is 15 minutes. 3. Further studies should be conducted of infrequent tasks and for indirect care before an RVU system can be accurately used.

Forecasting↗
PubMed2001

Age-based refinement of referral criteria for photoscreening.

OBJECTIVE: To evaluate examination results from preschool children referred from photoscreening, and to adjust referral criteria for suspected astigmatism. DESIGN: Cross-sectional study and noncomparative case series. PARTICIPANTS: Thirty-one thousand fifty-three preschool children. METHODS: Analysis of (1) referral rate and unreadable photograph rate for all children screened, (2) examination results and treatment plan for all children referred for suspected astigmatism, and (3) examination results and treatment for all referred children aged less than 1 year. MAIN OUTCOME MEASURES: Referral rate, unreadable photograph rate, predictive value positive, treatment plan. RESULTS: The referral rate dropped from 7.8% for children 6 to 11 months to 5.3% for all other ages. The unreadable photograph rate declined exponentially from 12.1% for children aged 6 to 11 months to 1.1% for children aged 4 years. The predictive value positive of a photoscreen referral for all children in the 6- to 11-month age group was 30%, and only 12 of the 94 referred children were treated. The predictive value positive for children less than 1 year of age referred with suspected astigmatism was even lower (25%), and only one child in this age group was treated. The predictive value positive increased with age, and a higher percentage of older children were treated. For children at least 3 years old referred for suspected astigmatism, the predictive value positive was 67% when the examination was performed by a pediatric ophthalmologist. Strabismus, anisometropia, and high hypermetropia were diagnosed in such patients age 2 and older but never in younger children. CONCLUSIONS: Children less than 1 year of age have a much lower pass rate from photoscreening than do older children because of a higher referral rate and higher unreadable rate in this age group. When these children are examined, significant pathosis is usually absent, and intervention is rarely initiated. Most children age 2 and older who are referred for suspected astigmatism have a high likelihood of significant pathosis. It is probably unnecessary to examine children less than age 2 when their photoscreening suggests only astigmatism; conversely, referrals should still be provided for these children when their screening suggests other potentially amblyogenic factors.

Age Factors↗
PubMedDate not supplied

Screening for visual impairment in older people: validation of the Cardiff Acuity Test.

Poor visual acuity (VA) is a risk factor for falls, and a common impediment to rehabilitation, but conventional VA testing is difficult in dysphasic, deaf or confused patients. In the Cardiff acuity test (CAT) observation of the subject's eye movements (preferential looking) indicates if they can see a vanishing optotype on a card. The test is quick, and requires no speech or understanding on the part of the subject. We consider its usefulness in frail, elderly patients. Seventy-three patients aged 47-99 (mean 78) years, were tested in good lighting, wearing their usual spectacles. Cards ordered 'A' to 'K' with increasingly faint targets were sequentially presented at 1 m, until the subject's eye movements indicated the target to be invisible. We then performed conventional Snellen acuity chart testing. Twenty-three were retested by a second observer, and 24 subjects were retested by the same observer on another day. We used correlation coefficients to confirm inter-observer (r=0.95, P<0.01), and test-retest (r=0.97, P<0.01) reliability. Snellen chart measurements of VA were possible in all but six subjects. The results of CAT and Snellen acuity tests showed statistically significant correlation (r=0.35, P<0.01). The World Health Organisation (WHO) define significant impairment as a Snellen test acuity below 6/18, and using the 'G' card as a threshold were able to detect this degree of impairment with a sensitivity of 91.7%, and a specificity of 90.9%. The CAT is reliable, and highly acceptable to elderly patients, and may be useful as a screening tool in clinical practice, and for epidemiological purposes.

Age Factors↗
PubMed1989

Evaluation of several tests in screening for chloroquine maculopathy.

Patients receiving antimalarial therapy, specifically hydroxychloroquine, for different periods were evaluated using contrast sensitivity test (CST) and results were compared with those of electro-retinography (EOG), and pattern visual evoked potential (PVEP), and a matching age control group. The results indicated CST to be most sensitive of the evaluated techniques particularly in patients under 40 years old. In 44.4% of the cases CST revealed macular dysfunction of which the other two methods of examination were not capable. Our findings suggest the CST is a reliable and practical method which could be used as an additional screening test for chloroquine maculopathy.

Adult↗
PubMed2002

The assessment and management of strabismus and amblyopia: a national audit.

AIMS: To determine what systems are in place within ophthalmic services for the assessment and management of children suspected of having amblyopia and strabismus. To find out what methods are used for the assessment of these children. METHODS: A questionnaire-based study auditing 288 orthoptic departments in the UK. RESULTS: Responses were received from 75% orthoptic departments. Most hospitals employ more than one system for the assessment of strabismus and amblyopia, which is generally dependent on route of referral. These include 'orthoptic assessment without refraction' (66%), 'combined orthoptist and ophthalmologist assessment' (66%), while 22% have an entirely orthoptist/optometric system. Ophthalmologists are involved in the initial assessment in 145 units (67%), whereas some units involve an ophthalmologist only if response to treatment is poor (15%), or if surgery is required (6%). Fourteen per cent of units reviewed all children, with discharge criteria being based on normal visual acuity (52%), accurate visual acuity (39%) and a normal orthoptic assessment (42%). Seventy-six per cent of units review some children, commonly as a result of family history (55%), parental concern (43%), poor co-operation (30%) and young age (72%). In the absence of squint or amblyopia children are discharged at the first visit, in only 8% of units. There is considerable variation in the tests used to assess visual acuity. LogMAR-based tests (eg EDTRS) are not routinely used in 75% of units. CONCLUSION: Different systems exist for the assessment and management of squint and amblyopia across the country. While much of this variation is to be expected given their possible aetiologies, some could be reduced to produce a more cohesive service. There is also considerable scope for rationalising the tests used to screen infants and children for amblyopia and strabismus.

Amblyopia↗
PubMed2002

Comparison of the frequency doubling technology screening algorithm and the Humphrey 24-2 SITA-FAST in a large eye screening.

PURPOSE: To compare the Frequency Doubling Technology (FDT) C20-1 screening algorithm and the Humphrey Field Analyser II (HFA) 24-2 SITA-FAST in a large eye screening. METHODS: In a non-randomized, prospective, free eye screening, the FDT Screening Protocol (C20-1 Screening Algorithm) was administered to 574 attendees (422 men and 152 women, average age 64, range 17-89 years) of the 1998 Veterans of Foreign Wars (VFW) Convention in San Antonio, Texas. Individuals who failed the FDT (two or more misses out of 17 locations) immediately underwent white-on-white threshold visual field perimetry (HFA 24-2, SITA-FAST). Humphrey visual field analysis included STATPAC and masked evaluations by three glaucoma specialists. RESULTS: Approximately one-tenth of the VFW conference attendees voluntarily presented themselves for screening. Among these 574 volunteers, 69 (12%) failed the FDT and underwent HFA analysis. Eighty-one per cent (56/69) of these FDT failures had abnormal HFA Glaucoma Hemifield Tests. Eighty-eight per cent (61/69) were judged to have nerve fibre type visual field loss on HFA by at least two of three masked examiners. A positive correlation existed between the number of FDT locations missed and the HFA mean deviation (r = 0.5, P = 0.0001). A similar association was observed when FDT and HFA results were analysed by quadrant (r = 0.5, P < 0.0001). CONCLUSION: There was a low false positive rate and a good positive predictive value comparing the FDT screening algorithm to the HFA 24-2 SITA-FAST in this study. This supports the potential use of FDT as an economical screening device.

Adolescent↗