Epidemiological patterns of ocular trauma B Thylefors
Abstract Ocular trauma is the cause of blindness in approximately half a million people worldwide, and many more have suffered partial loss of sight. Trauma is often the most important cause of unilateral loss of vision, particularly in developing countries. There is a cumulative risk of ocular trauma and visual loss during life, but the true incidence of accidents involving the eyes is not known. Males tend to have more eye trauma than females, and this is already apparent from childhood; lower socioeconomic classes are also more associated with ocular trauma. The setting for the occurrence of trauma is most commonly the workplace and, increasingly, road accidents. On the other hand, domestic accidents are probably under-reported.Of particular importance in some developing countries is the occurrence of superficial corneal trauma in agricultural work, often leading to rapidly progressing corneal ulceration and visual loss. The impact of ocular trauma, in terms of need for medical care, loss of income and cost of rehabilitation services when indicated, clearly makes the strengthening of preventive measures very worthwhile. Key words: Developing countries, ocular trauma, preventive strategies, risk factors, settings, socioeConomics.
The amount of blindness in the world caused by ocular trauma is not accurately known, but some Programme Manager, Programme for the Prevention of Blindness, World Health Orgrznizatton, Geneva, Switzerland.
estimates have been made, with varying conclusions. Thus, it has been put forward that ‘well over half a million people in the world are blind as a result of eye injuries” and it was estimated, in a review of epidemiological data from developing countries, that ‘up to 5% of all blindness found may be due to trauma’.’ If the number of blind is conservatively put at 27 to 35 million (Document WHO/PBL/ 87.14, World Health Organization, Geneva, 1987.), according to the compilation of data in the WHO Programme for the Prevention of Blindness, it is therefore reasonable to assume that there are at least half a million blind victims of ocular trauma. Whereas trauma is a very variable cause of blindness, it is invariably an important cause of monocular loss of sight. Available population-based data demonstrate that up to one-third of such monocular blindness may be due to severe trauma with late complications in some settings in developing c o u n t r i e ~Obviously, .~ these figures and rates vary, depending on particular circumstances such as the mining industry, agriculture, warfare, road accidents, etc., but trauma as a cause of visual loss, bilateral or unilateral, is of undeniable public health importance.
Epidemiology Visual impairment represents the final evidence of complications from ocular trauma, but it does not reflect on the overall occurrence of trauma. In one of the most carefully conducted epidemiological studies of ocular trauma in Nepal,4 it was found that 8.6 persons per 1000 had signs and history of ocular trauma, but only 38% had suffered any visual impairment; in the vast majority of those cases more than 70% - the visual impairment was unilateral.
Reprint requests: B. Thylefors, World Health Organization, Geneva, Switzerland. Epidemiological patterns of ocular trauma
There are no reliable data on the true incidence of ocular trauma. In the United States, it has been estimated that over 2.4 million eye injuries occur each year.' Some attempts have been made to consider incidence in terms of hospital consultations during a defined time period. Thus, the incidence of acute hospital-treated eye injuries was 423 per 100 000 population in the Dana county of Wisconsin in 1979.6In children ( < 16 years), a rate of 15.2 per 100 000 population was found in Maryland in 1982.7Even if this figure were to represent only a fraction ofthe true number oftraumas occurring in the defined population, it is likely that the events giving rise to later complications, in particular noticeable visual impairment, are reasonably well represented in such a study. The age factor is quite important to consider, both for the occurrence of trauma and for its later complications. It has been demonstrated that there is an increasing risk by age of ocular trauma and late complications with visual and this should be seen as an overall cumulative risk during life. Thus, in Nepal, the risk of having had an eye injury is 3.6 times higher for the person aged 50 years than for the person aged 15 years. There are, however, some particular groups that stand out in terms of ocular trauma and late complications. The main group in early life seems to be children from the age of five to eight years,'-'O and this particularly high risk remains up to late adolescence. A high proportion of eye injuries in this group is caused by perforating injury - up to more than 40% in some settings which explains the particular danger of late complications and often a poor visual One measure of the severity of ocular trauma and late complications in children is the experience, in Canada and Australia respectively, that one-third may result in a visual deficitI3 and that 7% of eyes were en~cleated.'~ In the Israeli study of eye injuries, it was found that 11Yo had a visual acuity of less than 6/60, and either phthisis or enucleation was the end result for close to 4% of eyes.l5 Males are usually more prone to ocular injury than females; this is seen clearly in children, where the ratio boys:girls involved in accidents with ocular trauma seems to be qround 4:1.12,13The male predominance remains higher also in later years, with some 84% of all ocular injuries occurring in Ireland being encountered in men.I6 The difference between sexes seems to disappear after the age of 70 years,I7 which is presumably a logical reflection of life-style and occupational patterns. Cultural factors may also bias the statistics in this field, when considering data on eye injuries related to industrial or 96
agricultural activities, which often are strictly men's or women's work in developing countries. Socioeconomic status is another confounding variable when considering the epidemiology of ocular trauma and late complications. Studies from Australia, Brazil and the United States demonstrate that ocular trauma tends to be more common and more severe amongst children from lower socioeconomic ~ t r a t a , ' ~and , ' ~ is also found more frequently amongst non-whites than amongst whites." It is interesting that the conclusion was similar from the Nepal Eye Study' but, whereas there were fewer accidents with eye injury in socioeconomically higher classes, this was also reflected in less trauma blindness in that group. When it comes to the discussion of causes of ocular trauma and late complications, the matter becomes complex, as there are such wide differences between the settings of available studies. Another difficulty is the use of different terminology concerning circumstances related to trauma and its complications. Ocular trauma occurring at the workplace seems to be the most common cause in industrialised countries, with half or more of all accidents involving the eyes taking place in that setting.'.'' It also seems that such accidents tend to be particularly severe, causing hyphaemas, ruptured globes and, as late complications, significant visual loss and often phthisis. Trauma related to sports and leisure activities is also reported as often severe, although usually much less commonly encountered than workplace accidents. Nevertheless, even if only around 3% of eye trauma may be caused by sports activities, the proportion of late and severe complications may be high, as hyphaemas and ruptured globes are over-represented in this particular group. Ball sports have been put forward as being of particular danger for such severe trauma with common late complications. There is a global trend for an increasing number of road accidents, particularly in developing countries, but a few highly developed countries have demonstrated clearly a decreasing incidence of ocular trauma, presumably as a result of laminated windscreens and the use of seat-belts, as advocated for a number of years." Domestic accidents are the most difficult to assess, as there is much more of a reporting problem than with workplace-related or road accidents. One of the few large-scale information systems on productrelated injuries to consumers is the National Electronic Injury Surveillance System in the USA,'* Australian and New Zealand Journal of Ophthalmology 1992; 20(2)
but it is based on self-reported ocular trauma and selected hospital samples, which makes it difficult to compare this information source with clinical studies. T h e Eye Trauma System is an additional source of clinical data on reported cases of trauma. l 8 ‘Leisure-related trauma’ is another vague group of accidents, occurring in various settings, from sports to champagne corks, and more recently, as reported from Canada, certain war games.*’ T h e latter exists also in some developing countries, as in India and Nepal. In these two countries, following the serialised television broadcast of a popular Indian epic which depicts numerous battle scenes showing the use of bows and arrows, there has been a spate of children with ‘bow and arrow’-caused injury to the eye (Pararajasegaram, R. Personal communication, 1991). Looking at the information available on ocular trauma and late complications in developing countries is indeed difficult. Not only is there scanty reporting on this matter, but there are also completely different settings for the occurrence of ocular trauma and for the ensuing late complications. The lack of general education as to possible preventive measures, together with difficult access for the primary treatment of ocular trauma and often non-existent specialist services for the management of late complications, tends to lead to a relatively high proportion of complications with severe visual loss. This is illustrated in some data from countries in South-East Asia. It is of interest to consider in more detail the circumstances around ocular injuries in two of these countries, which illustrate particular situations (Document WHO/SEA/Ophthal./28). I n Myanmar (ex-Burma), it has been reported that u p to 20’70 of all blindness is due to infected corneal injuries. I n fact, around 80% of these cases occur when handling rice or bamboo. T h e classic scenario is when the agricultural worker, while harvesting rice, develops corneal erosion which easily becomes infected and, later on, develops into a manifest progressive ulcer, finally leading to a lost eye. Delayed or absent medical care. seems to be the key factor in these cases, which are seen in most developing countries. Thus, in Madagascar, there is a well-known ‘rice-harvesting keratitis’, which in rural areas constitutes the fourth most common cause of visual loss. T h e progression of this keratitis can be quite rapid, with cases showing u p on the fourth day, having deep ulceration and usually with a visual acuity of light perception only (Andrianjatovo, J. & Liotet, S. Communication to the International Council of Epidemiological patterns of ocular trauma
Ophthalmology, Paris, 24 May 1991). It is in particular the rice-threshing (70%), together with scratches by leaves (20%), that lead to the initial corneal damage, which is very rapidly infected by bacteria and fungi, giving deep corneal ulceration as a late complication. Another particular situation of ocular injury with frequent late implications is found in Sri Lanka, as described below (Document WHO/SEA/Ophthal./ 10). There are more non-industrial injuries in Sri Lanka than in the more developed countries. What is perhaps peculiar to Sri Lanka is the fact that the most common injuries are from chemical burns and blast. Because of the rubber industry, acetic acid is freely available and is thrown at ‘enemies’to take revenge; almost all cases of acid burns are of this nature, whereas alkali burns are mostly accidental. The betel-chewing population often keep lime (calcium oxide)in their homes and the children accidently get it into their eyes. Blast injuries include those due to blasting of rocks, often industrially. What is now on the increase, however, are the accidents from the blasting of dynamite and hand bombs placed illegally to trap wild animals or for other purposes. As such blasting is illegal, no danger signals are displayed, and innocent persons become victims. Socioeconomic aspects Considering the impact of late complications of ocular trauma, it can be safely stated that it is very significant. There are, in the first instance, the medical aspects of late complication, implying the need for expensive hospitalisation and specialist services to deal with complications such as retinal detachment; frequent follow-up visits over an extended period of time are often needed in this context, which means lost income for the patient and expenditure for the care. Secondly, there is the functional aspect of the final outcome of late complications to ocular trauma, since visual loss, often to a severe degree, is a common feature in these cases. This may imply the need for vocational and other rehabilitation, or special education, for the patient, depending on age and other circumstances. Finally, there are the general socioeconomic aspects of late complications to ocular trauma, considering the very high cost to society in terms of expenditure for medical care and lost working capacity. One of the few cost estimates given in this context suggested around US$5 million in direct and indirect cost and 60 work years lost as the consequences per year of ocular trauma in one urban eye centre alone in.the USA.Z1It is against this background that one has to see the need for prevention and early and competent management of ocular trauma, in particular when late complications are likely to arise. 97
References 1. Anderson JDC, Foster A. Ocular trauma. Tropical Doctor 1989;I9:35-40. 2. Thylefors B. The prevention of penetrating injury ofthe eyes. Conference proceedings of the International Congress of Ophthalmology. Singapore, 1990 (in press). 3. NCgrel A-D, Carvalho D-A. FrCquence et gravitC des traumatismes oculo-palpibraux en milieu africain. Midecine d‘Afrique noire 1977;24:657-72. 4. SEVA Foundation (Ed. G Brilliant). The epidemiology of blindness in Nepal. SEVA Foundation, 1988. 5. Parver LM. Eye trauma - the neglected disorder. Arch Ophthalmol 1986;104:1452-3. 6. Karlson TA, Klein BEK. The incidence of acute hospitaltreated eye injuries. Arch Ophthalmol 1986;104:1473-6. 7. Strahlmann E, er al. Causes of paediatric eye injuries. Arch Ophthalmol 1990;108:603-6. 8. Macewen CJ. Eye injuries - a prospective survey of 5671 cases. Br J Ophthalmol 1989;73:888-94. 9. Gordon YJ, Mokete M. Paediatric ocular injuries in Lesotho. Documenta Ophthalmologica 1982;53:283-9. 10. Moreira CA, et al. Epidemiological study of eye injuries in Brazilian children. Arch Ophthalmol 1988;106:781-4.
11. Cole MD, Smerdon D. Perforating eye injuries caused by darts. Br J Ophthalmol 1988;72:511-4. 12. Koval R, et al. The Israeli ocular injury study. Arch Ophthalmol 1988; 106:776-80. 13. Laroche GR, et al. Epidemiology of severe eye injuries in childhood. Ophthalmology 1988;95: 1603-7. 14. Waddy PM. Causes and effects of eye injuries in children. Aust J Ophthalmol 1984;12:245-51. 15. Rapoport I, er a/. Eye injuries in children in Israel. Arch Ophthalmol 1990;108:376-9. 16. Canavan YM, er al. A 10-year survey of eye injuries in Northern Ireland. Br J Ophthalmol 1980;64:618-25. 17. Tielsch JM, er al. Time trends in the incidence of hospitalized ocular trauma. Arch Ophthalmol 1989;107:519-23. 18. Schein OD, et al. The spectrum and burden ofocular injury. Ophthalmology 1988;95:300-5. 19. Roper-Hall MJ. Prevention of blindness from trauma. Trans Ophthalmol SOCUK 1978;98:313-5. 20. Ryan EH, Lissner G. Eye injuries during “war games”. Arch Ophthalmol 1986;104: 1435-6. 21. Mufioz E. Economic costs of trauma, United States, 1982. J Trauma 1984;24:237-44.
Australian and New Zealand Journal of Ophthalmology 1992; 20(2)