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Risk, causes and outcomes of visual impairment after loss of vision in the non-amblyopic eye, a population-based study,
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CURRENT OPHTHALMOLOGY
References 1. Fant ME, Weisoly D: Insulin and insulin-like growth factors in human development: implications for the perinatal period. Semin Perinatol 25:426–35, 2001 2. Hellström A, Carlsson B, Niklasson A, et al: IGF-I is critical for normal vascularization of the human retina. J Clin Endocrinol Metab 87:3413–6, 2002 3. Savage MO, Camacho-Hubner C, Dunger DB, et al: Is there a medical need to explore the clinical use of insulin-like growth factor I? Growth Horm IGF Res 11(Suppl):S65–9, 2001
Risk, causes and outcomes of visual impairment after loss of vision in the non-amblyopic eye, a population-based study, by J. S. Rahi, S. Logan, C. Timms, I. Russel-Eggitt, and D. Taylor. Lancet 360:597–602, 2002 Background: Screening for amblyopia in early childhood is done in many countries to ensure that affected children are detected and treated within the critical period, and achieve a level of vision in their amblyopic eye that would be useful should they lose vision in their non-amblyopic eye later in life. We aimed to investigate the risk, causes, and outcomes of visual impairment attributable to loss of vision in the non-amblyopic eye. Methods: For 24 months from July, 1997, national surveillance was done to identify all individuals in the UK with unilateral amblyopia (acuity worse than 6/12) who had newly acquired vision loss in the non-amblyopic eye, resulting in acuity of worse than 6/12 or visual-field restriction precluding driving. Information about participants was obtained at presentation and 1 year later. Participants were categorised as having socially significant visual impairment, or visual impairment, severe visual impairment, or blindness, in accordance with WHO taxonomy. Findings: Of 370 eligible individuals, at presentation 104 (28%) had socially significant visual impairment, 180 (49%) visual impairment, and 86 (23%) severe visual impairment or blindness. The minimum risk of permanent visual impairment by age 95 years was 32.9 (95% CI 29.1–36.9) per 100,000 total population. The projected lifetime risk of vision loss for an individual with amblyopia was at least 1.2% (95% CI 1.1–1.4). Only 36 (35%) of 102 people previously in paid employment were able to continue. Interpretation: In the UK, where screening for amblyopia is under review, risk of serious vision loss affecting the non-amblyopic eye and its results are greater than that previously assumed. Thus, in addition to the benefits of improved vision in the amblyopic eye, treatment of amblyopia during childhood is a potentially valuable strategy to prevent incapacitating vision loss later in life.
Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye, by J. S. Rahi, S. Logan, M. Cortina-Borja, C. Timms, I. Russel-Eggitt, and D. Taylor. Lancet 360:621–2, 2002 Amblyopia arises from abnormal visual experiences in early childhood. Improved function of the amblyopic eye after visual loss in the non-amblyopic eye could be a model for residual neural plasticity. We aimed to establish the likelihood of, and predictive factors for, this improvement in function. We identified 254 individuals aged 11 years or older with unilateral amblyopia who were visually impaired after loss of vision in their non-amblyopic eye but had no other disorder affecting their amblyopic eye. 25 (10%) of 254 people had improved visual acuity in their amblyopic eye. These findings suggest there is some plasticity in the visual system of a few visually mature individuals with amblyopia, which warrants further study. Children should remain the focus of detection and treatment.
Comment The cost effectiveness of pre-school vision screening (PSVS) has recently been called into question.1,4 In particular, the lack of evidence that amblyopia constitutes a disability and that treatment works was highlighted. Recently, it has been shown that children who undergo a form of intensive PSVS have better visual outcomes at the age of 7 years than those who do not, demonstrating both that screening is beneficial and that treatment works.5 The first paper by Rahi et al3 addresses the extent to which amblyopia is a disability when there is loss of vision in the non-amblyopic eye. The British Ophthalmic Survey Unit (BOSU) was used to recruit 370 patients with amblyopia worse than 6/12 in the amblyopic eye and recently acquired loss of vision in the non-amblyopic of worse than 6/12 over a 2-year period. Two hundred and ninety-three of these patients still had visual acuity of worse than 6/12 in both eyes 1 year later. The least amblyopic were unable to drive and were arguably “economically blind” (27%), nearly half were visually impaired (43%) and almost a third were severely visually impaired or blind (30%), according to WHO taxonomy. Their findings suggest that a minimum of 185 people per year have visual loss in their non-amblyopic eye that has a significant impact on their quality of life. Half of those who had been in paid employment were unable to continue work due to reduced vision. The
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Surv Ophthalmol 48 (2) March–April 2003
WILLIAM GOOD
most common cause of visual loss overall were ARM (27%) vein occlusion (23%) and cataract (16%). Trauma was the most common cause in those under 65 (21%). These data make an important contribution to cost-effectiveness analysis of screening and treatment of amblyopia (i.e., monetary cost or gain to be expected as a result of a programme) which have hitherto been lacking. For example, offering the recently reported intensive screening program1 resulted in a reduction in the prevalence of amblyopia at the age of 7 years (of worse than 6/12, as in the Rahi papers) from 1.8% to 0.6%, that is, by 1.2%. Therefore the intensive screening program would have to be offered to 83 people to prevent one person from remaining amblyopic. That person’s lifetime risk of subsequent loss of their better eye would be 1.2% at Rahi et al’s lowest estimate; therefore, screening would need to be offered to 6,889 (83 83) children each year to prevent one individual suffering socially and economically important sight loss. If the costs to the state and/or individual of this can be modelled—cost-effectiveness equations become possible. The second paper2 looks at 254 of the original 370 patients who were over 11 years of age and who had no other disorders affecting the amblyopic eye. Twenty-five (10%) of these had an improvement in visual acuity of at least 2 Snellen lines. With univariate analysis improvement in visual acuity was most strongly correlated with new optical treatment and to a lesser extent with younger age, poorer vision in the non-amblyopic eye, and better visual acuity in the amblyopic eye. It is not clear whether the improvement in visual acuity is due to improvement in visual function or simply correction of a previously uncorrected refractive error, since many amblyopic subjects have only a balance lens in their glasses to correct their amblyopic eye. Since the latter explanation is likely to apply to at least a proportion of these cases, it is reasonable to predict that improvement of 2 lines or more is likely to be seen in less than 10% of amblyopes who lose vision in the non-amblyopic eye. As is common in amblyopia research the authors were unable to distinguish reliably between anisometropic and strabismic amblyopes. This information would be invaluable for cost-benefit analysis of PSVS, since this mostly detects anisometropic amblyopes and secondly if visual improvement was more likely in anisometropes or strabismics, it would both contribute to the screening debate and enable clinicians to make a more accurate prognosis. The authors and BOSU are to be congratulated on this work which makes a significant contribution to the evidence base that informs healthcare planning decisions in this controversial area.
Richard Harrad, FRCOphth Cathy Williams, FRCOphth Bristol, UK doi: 10.1016/S0039-6257(02)00454-X
References 1. Harrad R, McKee, S: Pre-school vision screening results of a systemic review. Surv Ophthalmol 43:374–6, 1999 2. Rahi JS, Logan S, Cortina-Borja M, et al: Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye. Lancet 360:621–2, 2002 3. Rahi JS, Logan S, Timms C, et al: Risk, causes and outcomes of visual impairment after loss of vision in the non-amblyopic eye, a population-based study. Lancet 360:597–602, 2002 4. Snowden S, Stewart-Brown S: Pre-school vision screening: results of a systemic review; CRD report 9. York: University of York, NHS Centre for Reviews and Dissemination, 1997 5. Williams C, Northstone K, Harrad RA, et al: Amblyopia treatment outcomes after screening before or at age 3 years: follow-up from a randomised controlled trial. Br Med J 324:1549–51, 2002
Age-related eye diseases: impact of hormone replacement therapy, and reproductive and other risk factors, by K. K. Snow and J. M. Seddon. Int J Fertil Womens Med 45:301–13, 2000 In Western countries, age-related macular degeneration is the leading cause of legal blindness in the population over 60 years of age, and cataract is the leading cause of visual impairment worldwide. Because postmenopausal women are living longer, they have a greater probability of developing a variety of age-related visual disorders. As the population ages, the physical and emotional toll of these ailments, as well as the burden on the health care system, will escalate. Currently, interventional therapy for age-related macular degeneration is limited to a small subpopulation of patients who can benefit from laser treatment, whereas surgery is the only effective treatment for cataract. The need for other therapeutic options and preventive measures remains a major challenge for the future. Studies among women have suggested that exposure to estrogens is associated with a reduction in risk of developing ocular diseases associated with aging. This article addresses the epidemiology of age-related macular degeneration and cataract, focusing on the specific risks for women, and discusses factors that may influence development or progression of these visual disorders.
CURRENT OPHTHALMOLOGY
References 1. Fant ME, Weisoly D: Insulin and insulin-like growth factors in human development: implications for the perinatal period. Semin Perinatol 25:426–35, 2001 2. Hellström A, Carlsson B, Niklasson A, et al: IGF-I is critical for normal vascularization of the human retina. J Clin Endocrinol Metab 87:3413–6, 2002 3. Savage MO, Camacho-Hubner C, Dunger DB, et al: Is there a medical need to explore the clinical use of insulin-like growth factor I? Growth Horm IGF Res 11(Suppl):S65–9, 2001
Risk, causes and outcomes of visual impairment after loss of vision in the non-amblyopic eye, a population-based study, by J. S. Rahi, S. Logan, C. Timms, I. Russel-Eggitt, and D. Taylor. Lancet 360:597–602, 2002 Background: Screening for amblyopia in early childhood is done in many countries to ensure that affected children are detected and treated within the critical period, and achieve a level of vision in their amblyopic eye that would be useful should they lose vision in their non-amblyopic eye later in life. We aimed to investigate the risk, causes, and outcomes of visual impairment attributable to loss of vision in the non-amblyopic eye. Methods: For 24 months from July, 1997, national surveillance was done to identify all individuals in the UK with unilateral amblyopia (acuity worse than 6/12) who had newly acquired vision loss in the non-amblyopic eye, resulting in acuity of worse than 6/12 or visual-field restriction precluding driving. Information about participants was obtained at presentation and 1 year later. Participants were categorised as having socially significant visual impairment, or visual impairment, severe visual impairment, or blindness, in accordance with WHO taxonomy. Findings: Of 370 eligible individuals, at presentation 104 (28%) had socially significant visual impairment, 180 (49%) visual impairment, and 86 (23%) severe visual impairment or blindness. The minimum risk of permanent visual impairment by age 95 years was 32.9 (95% CI 29.1–36.9) per 100,000 total population. The projected lifetime risk of vision loss for an individual with amblyopia was at least 1.2% (95% CI 1.1–1.4). Only 36 (35%) of 102 people previously in paid employment were able to continue. Interpretation: In the UK, where screening for amblyopia is under review, risk of serious vision loss affecting the non-amblyopic eye and its results are greater than that previously assumed. Thus, in addition to the benefits of improved vision in the amblyopic eye, treatment of amblyopia during childhood is a potentially valuable strategy to prevent incapacitating vision loss later in life.
Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye, by J. S. Rahi, S. Logan, M. Cortina-Borja, C. Timms, I. Russel-Eggitt, and D. Taylor. Lancet 360:621–2, 2002 Amblyopia arises from abnormal visual experiences in early childhood. Improved function of the amblyopic eye after visual loss in the non-amblyopic eye could be a model for residual neural plasticity. We aimed to establish the likelihood of, and predictive factors for, this improvement in function. We identified 254 individuals aged 11 years or older with unilateral amblyopia who were visually impaired after loss of vision in their non-amblyopic eye but had no other disorder affecting their amblyopic eye. 25 (10%) of 254 people had improved visual acuity in their amblyopic eye. These findings suggest there is some plasticity in the visual system of a few visually mature individuals with amblyopia, which warrants further study. Children should remain the focus of detection and treatment.
Comment The cost effectiveness of pre-school vision screening (PSVS) has recently been called into question.1,4 In particular, the lack of evidence that amblyopia constitutes a disability and that treatment works was highlighted. Recently, it has been shown that children who undergo a form of intensive PSVS have better visual outcomes at the age of 7 years than those who do not, demonstrating both that screening is beneficial and that treatment works.5 The first paper by Rahi et al3 addresses the extent to which amblyopia is a disability when there is loss of vision in the non-amblyopic eye. The British Ophthalmic Survey Unit (BOSU) was used to recruit 370 patients with amblyopia worse than 6/12 in the amblyopic eye and recently acquired loss of vision in the non-amblyopic of worse than 6/12 over a 2-year period. Two hundred and ninety-three of these patients still had visual acuity of worse than 6/12 in both eyes 1 year later. The least amblyopic were unable to drive and were arguably “economically blind” (27%), nearly half were visually impaired (43%) and almost a third were severely visually impaired or blind (30%), according to WHO taxonomy. Their findings suggest that a minimum of 185 people per year have visual loss in their non-amblyopic eye that has a significant impact on their quality of life. Half of those who had been in paid employment were unable to continue work due to reduced vision. The
236
Surv Ophthalmol 48 (2) March–April 2003
WILLIAM GOOD
most common cause of visual loss overall were ARM (27%) vein occlusion (23%) and cataract (16%). Trauma was the most common cause in those under 65 (21%). These data make an important contribution to cost-effectiveness analysis of screening and treatment of amblyopia (i.e., monetary cost or gain to be expected as a result of a programme) which have hitherto been lacking. For example, offering the recently reported intensive screening program1 resulted in a reduction in the prevalence of amblyopia at the age of 7 years (of worse than 6/12, as in the Rahi papers) from 1.8% to 0.6%, that is, by 1.2%. Therefore the intensive screening program would have to be offered to 83 people to prevent one person from remaining amblyopic. That person’s lifetime risk of subsequent loss of their better eye would be 1.2% at Rahi et al’s lowest estimate; therefore, screening would need to be offered to 6,889 (83 83) children each year to prevent one individual suffering socially and economically important sight loss. If the costs to the state and/or individual of this can be modelled—cost-effectiveness equations become possible. The second paper2 looks at 254 of the original 370 patients who were over 11 years of age and who had no other disorders affecting the amblyopic eye. Twenty-five (10%) of these had an improvement in visual acuity of at least 2 Snellen lines. With univariate analysis improvement in visual acuity was most strongly correlated with new optical treatment and to a lesser extent with younger age, poorer vision in the non-amblyopic eye, and better visual acuity in the amblyopic eye. It is not clear whether the improvement in visual acuity is due to improvement in visual function or simply correction of a previously uncorrected refractive error, since many amblyopic subjects have only a balance lens in their glasses to correct their amblyopic eye. Since the latter explanation is likely to apply to at least a proportion of these cases, it is reasonable to predict that improvement of 2 lines or more is likely to be seen in less than 10% of amblyopes who lose vision in the non-amblyopic eye. As is common in amblyopia research the authors were unable to distinguish reliably between anisometropic and strabismic amblyopes. This information would be invaluable for cost-benefit analysis of PSVS, since this mostly detects anisometropic amblyopes and secondly if visual improvement was more likely in anisometropes or strabismics, it would both contribute to the screening debate and enable clinicians to make a more accurate prognosis. The authors and BOSU are to be congratulated on this work which makes a significant contribution to the evidence base that informs healthcare planning decisions in this controversial area.
Richard Harrad, FRCOphth Cathy Williams, FRCOphth Bristol, UK doi: 10.1016/S0039-6257(02)00454-X
References 1. Harrad R, McKee, S: Pre-school vision screening results of a systemic review. Surv Ophthalmol 43:374–6, 1999 2. Rahi JS, Logan S, Cortina-Borja M, et al: Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye. Lancet 360:621–2, 2002 3. Rahi JS, Logan S, Timms C, et al: Risk, causes and outcomes of visual impairment after loss of vision in the non-amblyopic eye, a population-based study. Lancet 360:597–602, 2002 4. Snowden S, Stewart-Brown S: Pre-school vision screening: results of a systemic review; CRD report 9. York: University of York, NHS Centre for Reviews and Dissemination, 1997 5. Williams C, Northstone K, Harrad RA, et al: Amblyopia treatment outcomes after screening before or at age 3 years: follow-up from a randomised controlled trial. Br Med J 324:1549–51, 2002
Age-related eye diseases: impact of hormone replacement therapy, and reproductive and other risk factors, by K. K. Snow and J. M. Seddon. Int J Fertil Womens Med 45:301–13, 2000 In Western countries, age-related macular degeneration is the leading cause of legal blindness in the population over 60 years of age, and cataract is the leading cause of visual impairment worldwide. Because postmenopausal women are living longer, they have a greater probability of developing a variety of age-related visual disorders. As the population ages, the physical and emotional toll of these ailments, as well as the burden on the health care system, will escalate. Currently, interventional therapy for age-related macular degeneration is limited to a small subpopulation of patients who can benefit from laser treatment, whereas surgery is the only effective treatment for cataract. The need for other therapeutic options and preventive measures remains a major challenge for the future. Studies among women have suggested that exposure to estrogens is associated with a reduction in risk of developing ocular diseases associated with aging. This article addresses the epidemiology of age-related macular degeneration and cataract, focusing on the specific risks for women, and discusses factors that may influence development or progression of these visual disorders.