Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science Changing trends over the last decade in the aetiology of childhood blindness: a study from a tertiary referral centre Taylan Ozturk, Duygu Er, Aylin Yaman, A Tulin Berk

Paediatric Ophthalmology and ABSTRACT childhood blindness were presented to discern Unit, Department of Aims To discern treatable and preventable causes of treatable and preventable causes. Furthermore, Ophthalmology, Dokuz Eylul University School of Medicine, childhood blindness by evaluating the aetiologic factors, comparison of our current results with previously Izmir, Turkey and to compare the distribution of the most commonly published data from our tertiary referral centre affected anatomic sites of severe (SVI) aimed to highlight the trending topics in the aeti- Correspondence to with our previous published data. ology of childhood blindness in Izmir, Turkey.8 Professor A Tulin Berk, Methods The charts of 11 871 patients followed Paediatric Ophthalmology and Strabismus Unit, Department of between June 2002 and May 2014 were reviewed MATERIALS AND METHODS Ophthalmology, Dokuz Eylul retrospectively, and 695 patients (5.9%) who had SVI or We retrospectively reviewed the charts of 11 871 University School of Medicine, blindness in accordance with WHO criteria were enrolled. patients seen between June 2002 and May 2014 in Akarsu Sok, Mesa 2.Etap, No. The results of ophthalmologic examinations and 5, Urla, Izmir 35430, Turkey; our Paediatric Ophthalmology and Strabismus Unit, [email protected], coexistence of any systemic disease were documented which is a tertiary referral clinic and a part of a mul- [email protected] and checked against our published clinic data concerning tispeciality university hospital. All patients under- the aetiology of childhood blindness before 2002. went a full ophthalmologic examination, including Received 6 February 2015 χ2 test was used for statistics. fundoscopy, orthoptic assessment, cycloplegic Revised 1 June 2015 Results Mean age was 47.0±51.9 months (median: Accepted 21 June 2015 refraction, and binocular single vision, where Published Online First 24 months). Cortical visual impairment (CVI) was present cooperation was adequate. Best-corrected visual 9 July 2015 in 212 cases (30.5%) and 20.3% of those had a history acuity (BCVA) could be assessed using Snellen chart of premature birth. The most common anatomic sites of and Teller acuity cards whereas the optokinetic nys- SVI were (24.6%) and crystalline (17.1%). tagmus and CSM (central, steady, maintained) were When compared with our previous data, we found a taken into account according to the bilateral fixation fi signi cant increase in the prevalence of CVI (p=0.046) pattern in patients whose could not be and decrease in the frequency of SVI due to uveal measured. Signs of low vision such as , disorders (p<0.001). Prevalence of blindness secondary ocular bobbing or oculodigital massage were also to of prematurity reduced by a third fi noted. Orthoptic examination was performed with (p=0.280), and a signi cant decrease in -related the prism cover test or Hirschberg and Krimsky SVI (p=0.028) was achieved within the last decade. tests depending on the cooperation level of the Conclusions The prevalence of CVI was found to be fi patient. After anterior segment examination, cyclo- relatively increased due to the signi cant reduction in plegic retinoscopy was carried out in all patients to the frequency of preventable causes of SVI. Furthermore find out refractive errors, and confirmations were our clinical practice for visual rehabilitation in aphakia provided via autorefractometry (Retinomax; Right has resulted in a considerable decrease in SVI in the last Manufacturing, Virginia Beach, Virginia, USA) if decade. possible. Posterior segment examination was per- formed with an indirect ophthalmoscope and with ultrasonography when required. INTRODUCTION Cases with a significant visual impairment, which Children who are born blind or become blind in was defined as BCVA less than 0.3 in their better later life not only suffer but also become a burden eye using the Snellen chart in accordance with to their family and society for a lifetime. Since WHO criteria, were included in the present study. severe visual impairment (SVI) in children may Cases who had no central fixation and who had affect their development, education and employ- signs of very poor vision, like searching nystagmus, ment opportunities; early diagnosis is crucial for ocular bobbing or oculodigital massage, were also early intervention that might minimise the func- included. For the purpose of the study, major path- tional impact of blindness over society.12Many ology that had the greatest effect on vision was causes of childhood blindness such as retinoblast- taken into consideration in cases with multiple oma, vitamin A deficiency, and metabolic syn- ocular pathologies. Bilateral decreased visual dromes may be related to childhood mortality or response caused by damage to either the visual morbidity, so the early diagnosis of ocular disorders cortex or the geniculostriate visual pathways based – will affect the survival of the child.2 7 on MRI findings was defined as cortical visual For the purpose of designing efficient pro- impairment (CVI), unless any ocular abnormalities To cite: Ozturk T, Er D, grammes to prevent childhood blindness, obtaining related to visual loss existed. The results of Yaman A, et al. Br J reliable current data on major causes of SVI is man- ophthalmologic examinations and coexistence of Ophthalmol 2016;100:166– datory. Herein, most common aetiologic factors systemic diseases were documented in 695 patients 171. and affected anatomic sites that could be related to (5.9%) who met the inclusion criteria of the

166 Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science present study, and were compared with our previously published bilateral retinoblastoma (0.9%) and Leber congenital amaurosis clinic data on the aetiology of childhood blindness in Izmir (0.7%) were the other common genetic abnormalities in our before 2002.8 study population. The leading disorders within the prenatal/ The data were stored on a computerised database and ana- perinatal period were retinopathy of prematurity (ROP) (6.9%), lysed using SPSS V.16.0 for Windows (SPSS, Chicago, Illinois, congenital (6.3%), cerebral pathologies such as lissence- USA). Pearson χ2 and Yates corrected χ2 tests were used for stat- phaly, microcephaly, hypoplasia or agenesis of the corpus callo- istical analysis and a p value of below 0.05 was considered as sum (3.9%), congenital (2.9%), disorders significant. (2.7%), and pathologies (2.1%). Frequently diagnosed dis- orders related to the postnatal period were secondary optic RESULTS atrophy (3.2%), neoplasm (1.6%), meningitis (1.0%) and trau- A total of 695 patients (5.9%) were enrolled in the present matic brain injury (0.9%). The time of insult was unknown in study, of whom 292 (42.0%) were female and 403 (58.0%) 278 patients (40.0%), of whom 61.5% had CVI, including were male. No specific reason for the male preponderance was hypoxic ischaemic encephalopathy (HIE), , neuro- present in our hospital-based study. The mean age of patients at metabolic disorders and hydrocephalus. Chorioretinal dysplasia the first ophthalmologic examination in our Paediatric (21.6%) and primary optic atrophy (9.0%) were the other Ophthalmology and Strabismus Unit was 47.0±51.9 months, common pathologies in such cases. ranging from 1 month to 17 years (median: 24 months). The majority of the study participants were observed before the age Avoidable causes of 47 months (mean age of the study population), accounting In the present study, the leading pathology that could be for almost two-thirds of all cases. Patients who presented before encountered in the treatable causes of SVI was congenital and 1 year of age constituted 44.3% of the entire study population. juvenile (16.4%). A family history of consanguinity Visual acuity was assessed using the Snellen chart in 274 cases was found to be present in 196 of the total 695 cases (28.2%) (39.4%), and with Teller acuity cards in 77 cases (11.1%), in our study population (table 3). Frequency of consangineous whereas visual perception could not be measured in 344 marriage was higher, especially in cases with congenital glau- patients (49.5%) in whom searching nystagmus, loss of fixation, coma (45.0%), optic nerve disorders (40.3%) and globe path- ocular bobbing, or oculodigital massage were present due to the ologies (37.5%). In 136 cases (19.6%), SVI was found to be major ocular or neurologic pathologies that cause SVI. related to various pathologies, which mostly may be preventable Nystagmus was found in 197 patients (28.3%), most frequently with genetic counselling such as Down’s syndrome, metabolic of the pendular type (14.2%; 99 cases). Strabismus was present disorders, retinoblastoma and hereditary chorioretinal in 200 patients (28.8%); among cases with horizontal strabis- mus, was more commonly seen in cases with a con- genital aetiologic factor (55.5%), although a frequent type of Table 1 Demographics, ophthalmologic findings, and concomitant strabismus was in patients with poor vision related to systemic pathologies acquired aetiologic factor (58.4%). Exotropia was more fre- quently seen in patients with CVI (p<0.001). Cases with retinal No. of patients Percentage of patients or lenticular disorder had a tendency to develop eso deviations Gender (p=0.019 and p=0.045, respectively). The mean angle of stra- Female 292 42.0 bismus was found to be 22.9±12.0 prism dioptres (8–75 PD) Male 403 58.0 and 18.5±8.4 prism dioptres (8–45 PD) in patients with eso Mean age (months) 47.0±51.9 (1 month–17 years) and exo deviations, respectively. Developmental delay defined as Mean BCVA (logMAR) (n=351) 0.95±0.37 (0.50–2.00) a problem in one or many areas such as gross and fine motor Nystagmus 198 28.5 skills, social and emotional skills, language and cognitive skills Pendular nystagmus 99 14.2 that was diagnosed by a paediatric neurologist was present in Searching nystagmus 71 10.2 16.8% of the study population. Demographics, ophthalmologic Jerk nystagmus 17 2.4 findings and concomitant systemic pathologies are shown in Vertical nystagmus 7 1.0 table 1. Rotatory nystagmus 4 0.6 Strabismus 200 28.8 Blindness by anatomic site Esotropia 110 15.8 Two hundred and twelve patients (30.5%) had CVI and 20.3% Exotropia 89 12.8 of those had a history of premature birth. Asphyxia, metabolic Isolated vertical deviation 1 0.1 disorders, genetic syndromes, infections and trauma were identi- Developmental delay 117 16.8 fied as the other risk factors for CVI in our study population. Concomitant systemic pathologies The following three most frequently involved anatomic sites Epilepsy 51 7.3 were retina (24.6%), crystalline lens (17.1%) and optic nerve Hydrocephalus 20 2.9 (9.6%), which are summarised in table 2. Lissencephaly 2 0.3 Microcephaly 6 0.9 Aetiology according to the time of insult leading to visual Aplasia of the corpus callosum 15 2.2 impairment Encephalomalacia 9 1.3 Genetic disorders were identified in 26.2% of patients. Craniosynostosis 4 0.6 Chorioretinal dystrophies were found in 64 cases (9.2%). Skeletal dysplasia 5 0.7 Neurometabolic disorders including mucopolysaccharidosis, Cleft palate and lip 3 0.4 galactosemia, urea cycle disorders, Lowe syndrome, Rett syn- drome and Canavan disease were diagnosed in 33 cases (4.7%). BCVA, best-corrected visual acuity; logMAR, Logarithm of the Minimum Angle of Resolution. Oculocutaneous albinism (3.9%), Down’s syndrome (2.4%),

Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 167 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science

Table 2 Anatomic site of abnormality leading to visual Table 2 Continued impairment No. of Percentage of No. of Percentage of Anatomic site patients patients Anatomic site patients patients 3 0.4 Cortical 212 30.5 Bilateral congenital (associated 5 0.7 Hypoxic ischaemic encephalopathy/ 61 8.8 with refractive errors) ancephalomacia Cerebral palsy/periventricular 41 5.9 leukomalacia Epilepsy 29 4.2 dystrophies. Infectious causes primarily related to SVI were Metabolic disorders 26 3.7 diagnosed in 1.2% of the cases (table 3). Agenesis of the corpus callosum 15 2.2 Down’s syndrome 13 1.9 Developmental delay 11 1.6 Comparison with our previous clinic data Meningitis 6 0.9 When we compared the current results with our previously pub- Microcephaly 4 0.6 lished clinic data concerning the aetiology of childhood blind- fi Trauma 3 0.4 ness in Izmir before 2002, a statistically signi cant increase in Lissencephaly 2 0.3 the incidence of CVI (p=0.046), and a decrease in the inci- Edwards syndrome (Trisomy 18) 1 0.1 dence of uveal disorders (p<0.001) were found. Prevalence of Retina 171 24.6 blindness secondary to ROP reduced by a third (p=0.280), and fi Chorioretinal dystrophies 64 9.2 a signi cant decrease was also achieved in aphakia-related SVI Retinopathy of prematurity 48 6.9 (p=0.028) over the last decade (table 4). Oculocutaneous albinism 27 3.9 Bilateral spontaneous retinal 10 1.4 DISCUSSION detachment As it is estimated that 500 000 children will become blind each 8 1.2 year, the emotional, social and economic costs of childhood Bilateral retinoblastoma 6 0.9 blindness to society have been gradually rising.12Early diagno- Leber congenital amaurosis 5 0.7 sis helps to reduce childhood mortality since the causes of blind- Coats’ disease 2 0.3 ness may also be related to lethal diseases, especially in the early – Bilateral choroidal haemangioma 1 0.1 decades of life.2 6 Up to 60% of newly diagnosed blind children Lens 119 17.1 die within 2 years of becoming blind in rural communities, Aphakia 44 6.3 however the UK surveillance study reported a figure as low as – Aphakic glaucoma 24 3.5 <10%.2 4 The prevalence of childhood blindness varies from Cataract 24 3.5 0.02% to 0.12% according to the socioeconomic status of the Pseudophakia 22 3.2 studied population, and over 70% of children suffering from Subluxated crystalline lens 5 0.7 blindness worldwide live in the poorest countries of Africa and – Optic nerve 67 9.6 Asia.4 6 Primary optic atrophy 26 3.7 Avoidable causes include preventable and treatable disorders Secondary optic atrophy 22 3.2 that are related to childhood blindness. Avoidable measures such 12 1.7 as refractive errors, , and ocular trauma Isolated disc coloboma and morning 7 1.0 have been reported as the leading causes of childhood eye mor- – glory disc bidity and SVI in rural communities.9 14 However, in developed Refractive 40 5.8 countries, unavoidable causes including genetic diseases, con- High 20 2.9 genital anomalies and disorders of the central nervous system Ametropic amblyopia 14 2.0 have been reported as the main aetiologic factors for SVI.1615 Meridional amblyopia 6 0.9 The frequency of unavoidable causes varies in different case Congenital glaucoma/buphthalmos 20 2.9 series between 25.5% and 82% according to the socioeconomic Idiopathic nystagmus 20 2.9 status of the communities. Kong et al6 reported that a mean of 18 2.6 51% of SVI cases were found to be related to avoidable causes Sclerocornea 5 0.7 in developing countries. In the present study, the prevalence of 5 0.7 diagnosis of any unavoidable aetiologic factors was found to be 3 0.4 38.3%, which is in accordance with the data of developing 3 0.4 countries. A comparison of causative aetiologic factors for SVI Corneal scarring 2 0.3 between our study and other selected studies is given in table 5. Globe 16 2.5 and especially vitamin A deficiency as well as Microphthalmos 7 1.0 infectious diseases of the ocular surface or adnexa such as trach- Anophthalmos 4 0.6 oma have still been encountered and are considerable causative – Nanophthalmos 3 0.4 factors of childhood blindness in low-income countries.9 14 A Cryptophthalmos 1 0.1 lack of such disorders within the aetiologic factors of SVI in our 1 0.1 study population may be attributed to the national health pro- 7 1.0 gramme, which has improved over the past four decades. In Choroidal coloboma 4 0.6 addition, our tertiary referral centre that is located in the Continued western region of the country and covers a hinterland with

168 Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science

Table 3 Avoidable causes of visual impairment No. of Percentage of Consanguinity rates N Causes patients patients (%)

Treatable 293 42.2 55 (18.8) Cataract/subluxated crystalline lens 95 13.7 21 (22.1) Retinopathy of prematurity 48 6.9 4 (8.3) Refractive amblyopia 40 5.8 5 (12.5) Aphakic glaucoma 24 3.5 3 (12.5) Secondary optic atrophy (secondary to hydrocephalus, medulloblastoma, and 22 3.2 5 (22.7) craniopharyngioma) Congenital glaucoma 20 2.9 9 (45.0) Corneal disease (keratoconus, corneal dystrophies, corneal opacity or scarring) 13 1.9 3 (23.1) Spontaneous 10 1.4 3 (30.0) Retinitis 8 1.2 – Meningitis 5 0.7 1 (20.0) Congenital ptosis 5 0.7 1 (20.0) Uveitis 3 0.4 – Preventable 136 19.6 73 (53.7) Genetic diseases 132 19.0 72 (54.5) Prenatal/perinatal infections 4 0.6 1 (25.0)

Table 4 The comparison of current results with our previously published clinic data8 Previously published clinic data Results of the present study ( June 1998–May 2002) ( June 2002–May 2014) n=148/998 (14.8%) n=695/11 871 (5.9%) Mean age: 36.6 months Mean age: 47 months

No. of patients Percentage of patients No. of patients Percentage of patients p Value (χ2 test)

Retina 37 25.0 171 24.6 0.919 ROP 14 9.4 48 6.9 0.280 Macular dystrophy 11 7.4 64 9.2 0.491 Albinism 6 4.0 27 3.9 0.923 Leber amaurosis 3 2.0 5 0.7 0.306 Retinitis 2 1.3 8 1.2 1.000 Retinoblastoma 1 0.6 6 0.9 1.000 Other –– 13 1.9 Lens 34 22.9 119 17.1 0.094 Aphakia 17 11.4 44 6.3 0.028 Pseudophakia 7 4.7 22 3.2 0.343 Aphakic glaucoma 6 4.0 24 3.5 0.720 Cataract 3 2.0 24 3.5 0.524 Lens subluxation 1 0.6 5 0.7 1.000 Cortical 33 22.2 212 30.5 0.046 Optic nerve 16 10.8 67 9.6 0.664 Hypoplasia 6 4.0 12 1.7 0.075 Primary atrophy 5 3.3 26 3.7 0.831 Secondary atrophy 5 3.3 22 3.2 0.894 Other –– 7 1.0 Uvea 9 6.0 7 1.0 <0.001 Cornea 3 2.0 18 2.6 0.690 Globe 2 1.3 16 2.3 0.468 Glaucoma 1 0.6 20 2.9 0.119 Idiopathic nystagmus 5 3.3 20 2.9 0.744 Refractive 7 4.7 40 5.8 0.621 Congenital ptosis (+RE) –– 5 0.7 – Treatable causes 62 41.9 293 42.2 0.952 Preventable causes 41 27.7 136 19.6 0.027 RE, ; ROP, retinopathy of prematurity.

Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 169 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science

Table 5 The comparison of causative aetiologic factors for SVI between our study and other selected studies Major anatomic sites of involvement Cornea and Optic Whole Refractive Lens Glaucoma Uvea Retina nerve globe and Countries with studies N Age CVI (%) (%) (%) (%) (%) (%) (%) (%) others (%)

Rahi et al,3 UK (HB) 493 <16 years 40.0 6.0 – 3.0 2.0 NA 24.0 23.0 2.0 Kong et al, 6USA (SB) 3070 School age 18.0 1.0 1.0 2.0 3.0 4.0 25.0 22.0 24.0 Cetin et al,8 Turkey (HB) 998 36.6 months 22.2 2.0 4.7 22.9 0.6 6.0 25.0 10.8 4.6 Muhit et al,9 Bangladesh (SB) 1935 132 months – 26.6 – 32.5 4.3 2.0 12.7 8.0 14.1 Mehari et al,10 Ethiopia (HB) 735 9.4 years – 62.0 14.5 2.7 0.4 1.1 ––19.3 Onakpoya et al,11 Nigeria (HB) 286 <15 years – 37.1 14.3 6.6 1.4 2.1 ––38.4 Muecke et al,12 Myanmar (SB) 208 <16 years 1.0 43.6 – 14.4 5.4 2.5 7.4 4.0 21.2 Ntim-Amponsah et al,13 Ghana (SB) 244 School age 2.7 28.8 – 15.8 10.6 - 6.8 6.2 29.1 Sitorus et al,14 Indonesia (SB) 479 School age – 16.1 – 16.4 1.7 7.7 18.9 5.0 34.2 Ruhagaze et al,19 Burundi (SB) 117 <16 years – 23.9 10.1 18.3 8.3 14.7 1.8 11.9 11.1 Krishnaiah et al,20 South India (SB) 111 <16 years – 8.1 1.8 9.9 8.1 4.5 18.9 6.3 42.4 Koay et al,21 Malaysia (SB) 469 <18 years NA 5.1 NA 17.2 7.6 0.7 17.4 NA 2.5 Limburg et al,22 Vietnam (PB/SB) 28 800 <15 years 1.5 24.1 0.7 15.1 5.4 2.9 24.6 10.2 10.9 Sia et al,23 Cambodia (SB) 95 <16 years – 25.8 1.6 27.4 3.2 3.2 21.0 3.2 14.5 Heijthuijsen et al,24 Suriname (HB/ 4643 <16 years 7.7 6.2 – 15.4 3.1 1.5 33.8 7.7 6.1 SB) Current study, Turkey (HB) 11 871 47.0 months 30.5 2.6 5.8 17.1 2.9 1.0 24.6 9.6 5.9 HB, hospital based study; PB, population based study; SB, school for the blind based study.

comparatively higher socioeconomic and sociocultural status cases (30.5%) and 20.3% of those were born prematurely. Any may also have a positive impact on such data. Since approxi- stage of ROP coexisted in 35 cases with CVI (16.5%) in the mately 65% of the entire study population were referred to our present study, and none of them developed end-stage clinic before the age of 4 years, blindness secondary to infec- retinopathy. tions of the cornea or conjunctiva was not seen in any of the Retina is the most common anatomic site of involvement in cases due to early diagnosis and complete treatment of keratitis childhood blindness worldwide.4 The incidence of ROP has or severe conjunctivitis, which could have progressed to corneal increased in the last decades because of the augmented fre- scarring without intervention. Correction of refractive errors quency of premature births relevant to the developments in with appropriate spectacles, setting an amblyopia treatment with assisted reproduction techniques, and advances in neonatology eye patching if required, and scheduling regular follow-up visits that allow a great improvement in survival rates of more imma- in the first decade of life have helped to eliminate refractive ture neonates. However, we found a reduction of approximately amblyopia in many study cases. The low prevalence of refractive one-third in the frequency of blindness secondary to ROP in the amblyopia in the present study should also be attributed to the last decade. With the institution of carefully timed screening improving performance of school health services that regularly and scheduling proper treatment with laser photocoagulation or monitor children for refractive errors and refer affected subjects vitreoretinal surgery in required cases, the frequency of to an ophthalmologist. ROP-related blindness has substantially decreased. Blencowe Compared with our published clinic data, a statistically signifi- et al18 reported a retinopathy-related SVI rate of 10.8% among cant decrease was detected in the incidence of preventable preterm babies who developed any stage of ROP in 2010. In the causes and especially genetic disorders. In 2002, the rate of con- USA, ROP was one of the three leading causes of childhood sanguineous marriage was reported to be 15.1% among subjects blindness.6 In middle and low income countries, remarkably, a aged 15 years or older, and 55.8% of those married their first- lower frequency of ROP-related SVI was reported in studies degree relatives.16 A population-based survey was conducted in carried out on students in schools for the blind.9141920 2011 on young adults between the ages of 15 and 24 years that Nevertheless such data are likely to be underrepresented due to represented 16.8% of the entire Turkish population. The fre- higher mortality rates of premature infants in poor quency of consanguineous marriage was found to be 21.2% in communities. this survey; furthermore, participants who married a first-degree Among blind children, the frequency of lenticular disorders relative constituted 51.9% of the endogamous population.17 was found to be between 10% and 20% in developing countries – – Owing to improvements in invasive care facilities, the survival and <5% in developed countries.1 7142022 Lenticular disor- rate of children with various genetic or metabolic disorders has ders that are still commonly related to TORCH infections have increased. Cases with perinatal asphyxia and related HIE that remained one of the main causes of SVI in low-income societies. are significant risk factors for several mental and neurological Preventive general public health care policies such as maternal disorders have also become more likely to survive during recent immunisation against rubella and rubeola have dramatically decades. In accordance with the present study, CVI has been reduced the burden of blindness due to in – – – found to be the most frequent aetiologic factor for childhood such countries.4 71114 19 24 In the present study, lenticular dis- blindness in the USA.6 Khetpal and Donahue also reported that orders were identified in 17.1% of cases with SVI, of whom premature birth with a prevalence of 29% was one of the major 57.1% had aphakia following cataract surgery. Compared with risk factors for CVI.15 In our study, CVI was present in 212 our previous data, a significant decrease was found in the

170 Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com Clinical science prevalence of aphakia-related SVI, however the frequency of Contributors I certify on behalf of myself and all coauthors that we have all aphakic glaucoma was not significantly different between two participated sufficiently in the conception and design of this work, and interpretation study populations. The considerable decrease in SVI in such of the data, as well as in writing the manuscript, to take responsibility for it and accept its conclusions. cases may be due to an improvement in our clinical practice for visual rehabilitation, which included aphakic contact lenses in Competing interests None declared. infancy, plus bifocals in toddlerhood, and intraocular lens Ethics approval Institutional Review Board. implantation thereafter. Scheduling postoperative follow-up Provenance and peer review Not commissioned; externally peer reviewed. visits is also important to diagnose and treat any possible aphakia complications such as amblyopia, strabismus and REFERENCES glaucoma. 1 Solebo AL, Rahi J. Epidemiology, aetiology and management of visual impairment – Because the nature of uveal disorders has been well under- in children. Arch Dis Child 2014;99:375 9. fl 2 Gilbert C, Foster A. Childhood blindness in the context of VISION 2020: the right to stood and more potent anti-in ammatory therapeutics have sight. Bull World Health Organ 2001;79:227–32. been developed based on an immunomodulatory approach over 3 Rahi J, Cable N, on behalf of the British Childhood Visual Impairment Study Group the last two decades, the incidence of SVI secondary to uveal (BCVISG). Severe visual impairment and blindness in the UK. Lancet disorders has gradually decreased.25 Compared with our previ- 2003;362:1359–65. fi 4 Gilbert C. 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Pediatr Res Dec 2013;74(Suppl 1):35–49. factors give a snapshot of the proportion of the population 19 Ruhagaze P, Njuguna KK, Kandeke L, et al. Blindness and severe visual impairment under 18 years of age who had suffered from any ocular dis- in at school for the blind in Burundi. Middle East Afr J Ophthalmol order at any one point in time. In the present study, the fre- 2013;20:61–5. quency of SVI among children who were referred to an 20 Krishnaiah S, Subba Rao B, Lakshmi Narasamma K, et al. A survey of severe visual impairment in children attending schools for the blind in a coastal district of Andhra ophthalmologist was found to be 5.9%, which is approximately – – Pradesh in South India. Eye (Lond) 2012;26:1065 70. 10 20 times higher than the prevalence data obtained from true 21 Koay CL, Patel DK, Tajunisah I, et al. A comparative analysis of avoidable causes of population-based studies. Governments ought to ameliorate childhood blindness in Malaysia with low income, middle income and high income their policies on developing national screening programmes for countries. Int Ophthalmol 2015;35:201–7. treatable causes, such as congenital cataract, amblyopia, ROP 22 Limburg H, Gilbert C, Hon DN, et al. Prevalence and causes of blindness in children in Vietnam. Ophthalmology 2012;119:355–61. and congenital glaucoma. Genetic counselling and parental edu- 23 Sia DIT, Muecke J, Hammerton M, et al. A survey of visual impairment and cation are also crucial, especially in countries with a high rate of blindness in children attending four schools for the blind in Cambodia. Ophthalmic consanguinity. Epidemiol 2010;17:225–33. 24 Heijthuijsen AAM, Beunders VAA, Jiawan D, et al. Causes of severe visual Acknowledgements Neither this manuscript nor one with substantially similar impairment and blindness in children in the Republic of Suriname. Br J Ophthalmol content under our authorship has been published or is being considered for 2013;97:812–15. publication elsewhere. We certify that any affiliations with or involvement in any 25 Hettinga YM, Verhagen FH, van Genderen M, et al. Characteristics of childhood organisation or entity with direct financial interest in the subject matter or materials uveitis leading to visual impairment and blindness in the Netherlands. Acta discussed in the manuscript are disclosed in the paper. Ophthalmol 2014;92:798–804.

Ozturk T, et al. Br J Ophthalmol 2016;100:166–171. doi:10.1136/bjophthalmol-2015-306737 171 Downloaded from http://bjo.bmj.com/ on February 18, 2016 - Published by group.bmj.com

Changing trends over the last decade in the aetiology of childhood blindness: a study from a tertiary referral centre Taylan Ozturk, Duygu Er, Aylin Yaman and A Tulin Berk

Br J Ophthalmol 2016 100: 166-171 originally published online July 9, 2015 doi: 10.1136/bjophthalmol-2015-306737

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