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Middle East African Journal of Ophthalmology Middle East African Journal of Ophthalmology
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Year : 2008  |  Volume : 15  |  Issue : 1  |  Page : 3-6 Table of Contents     

Causes of blindness among adult Yemenis: A Hospital-based study

Eye Department, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Republic of Yemen and Ibn Al-Haitham Eye Center, University of Science and Technology, Sana'a, Republic of Yemen, Yemen

Date of Web Publication13-Jul-2009

Correspondence Address:
Mahfouth A Bamashmus
Assistant Professor of Ophthalmology, Faculty of Medicine and Health Sciences, Sana'a University, PO Box 19576, Sana'a
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-9233.53367

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Purpose: This hospital-based retrospective study was aimed to assess the causes of blindness among adults aged 17 years and over who attended a teaching eye hospital in Yemen.
Methods: The case notes of 3845 consecutive new patients over 12 months attending Ibn Al-Haitham Eye Center which is affiliated to the University of Science and Technology in Sana'a (the capital of Yemen) were retrieved and analysed. Data collected included age, gender, chief complaint and complete eye examination.
Results: 7.7 percent (296) were uniocularly blind and 11.2 percent (432) were binocularly blind (best corrected visual acuity <3/60 in the better eye). The leading causes of uniocular blindness were cataract, trauma related ocular complications, corneal opacity, amblyopia and glaucoma. Binocular blindness was mainly due to cataract, glaucoma, diabetic retinopathy, age related macular degeneration and corneal opacity.
Conclusions: These data imply that the preliminary results give us some insight about the magnitude of the problem of blindness in Yemen while awaiting a national survey on the prevalence and causes of blindness. Cataract was found to be the main cause of unilateral and bilateral blindness and this will require surgical relief, either in public hospitals, private hospitals and clinics, or in eye camps. Trauma related ocular complications were found to be the second most common cause of uniocular blindness. Health education, implementing work safety measures and bringing ophthalmological care to the doorstep of underprivileged rural community will improve their level of awareness.

Keywords: blindness, cataract, glaucoma, corneal opacity, Yemen

How to cite this article:
Al-Akily SA, Bamashmus MA. Causes of blindness among adult Yemenis: A Hospital-based study. Middle East Afr J Ophthalmol 2008;15:3-6

How to cite this URL:
Al-Akily SA, Bamashmus MA. Causes of blindness among adult Yemenis: A Hospital-based study. Middle East Afr J Ophthalmol [serial online] 2008 [cited 2020 Aug 15];15:3-6. Available from: http://www.meajo.org/text.asp?2008/15/1/3/53367

The Republic of Yemen is a Middle Eastern developing country lies in the Arabian Peninsula, southwest of Asia. Bordered on the north by Saudi Arabia, on the south by the Arabian Sea and the Gulf of Aden, on the east by the Sultanate of Oman and on the west by the red sea. Its total area exceeds 555,000 km excluding the Empty Quarter Dessert. The total population of Yemen is 19,685,161 (49.5 percent of whom are aged 17 years and above). The capital city, Sana'a has an estimated population of 1,488,108. [1] The country is poor with a human development index of 0.486; human poverty index is 47.0, a life expectancy of 61.1 and a literacy rate of 50 percent. [2]

Uniocular blindness is defined as a corrected visual acuity 3/60 or below in one eye. Binocular blindness is defined as a corrected visual acuity of 3/60 or below in both eyes . [3] Blindness constitutes significant public health problem in many countries.

Family health survey conducted by Ministry of Health in 2003 revealed that 2.9 percent of the population had some sort of self reported handicap, with visual handicap representing 36 percent of the total identified disabled individuals in the country. [4]

The available data suggests that in the year 2000 there were approximately 50 million blind people in the world. The majority live in Asia and Africa. Approximately 8-10 million people become blind each year and it is estimated that around 6-8 million people who are blind die each year. The result is a net increase of 1-2 million blind person per year. The increase in blindness is due to an increasing world population and increased life expectancy, with more people in the world leaving beyond the age of 60 years. [5]

Of the 50 million blind people in the world, it is estimated that, approximately half is due to cataract, 15 percent due to trachoma and 4 percent due to paediatric blindness. The other causes of blindness are glaucoma (approximately 15 percent) and diabetic retinopathy (5 percent). [5] Despite the efforts of UN agencies, national governments and non-governmental organizations, blindness is an increasing problem causing loss of quality of life to the individual and an economic burden on the individual, family and society in general.

There has been no national blindness survey in Yemen. The available data on the prevalence and causes of blindness in Yemen are studies done in focal areas of the country. [6],[7] To our knowledge there has been no published hospital-based studies on the causes of blindness in Yemen.

   Patients and Methods Top

We studied 3845 consecutive patient records (2246 males and 1599 females) who attended the Ibn Al-Haitham Eye Centre in Sana'a during the academic year 2001/2002. The study was restricted to persons aged 17 years and over. Children were not included.

After initial registration and history taking, all patients had their visual acuity measured using the Snellen visual acuity chart projector at 6 meters; spectacles were worn if necessary to give the best corrected vision. Patients were then examined with a slit lamp, direct or indirect ophthalmoscopy, the intraocular pressure was measured by Goldmann applanation tonometer in the suspected cases of glaucoma and to those above the age of 40 years. Those patients with a best corrected visual acuity of less than 3/60 in both eyes were categorized as binocularly blind (WHO standards) and those with best corrected visual acuity of less than 3/60 in one eye but 3/60 or better in the other eye were classified as uniocularly blind.

In most cases the cause of blindness was a single disorder. When there was more than one pathology in a patient, the WHO recommendation was adhered to: namely the most avoidable or preventable pathology was chosen or, alternatively, the cause that led to the last event rendering the individual sightless [8] . This principle was also adhered to while classifying the causes of blindness in unilateral cases when multiple causes were present in one eye. After establishing the diagnosis, medicines or glasses were prescribed as appropriate. Data were entered into an Excel 2000 program and analyzed.

   Results Top

A total of 3845 new patients aged over 17 years were seen during the study period. Of these, 296 (7.7 percent) were uniocularly blind while 432 (11.2 percent) had binocular blindness.

Out of the 296 uniocular blind there were 196 (66.2 percent) males and 100 (33.8 percent) females. Cataract and ocular trauma related complications were the commonest causes of uniocular blindness. [Table 1] shows the major causes of uniocular blindness.

[Table 2] shows the major causes of bilateral blindness. Once again cataract was the commonest cause of bilateral blindness. There were 258 (59.7 percent) males and 174 females (40.3 percent). [Table 3] shows the statistical analysis of bilateral blindness in males and females. [Table 4] compares leading causes of bilateral blindness in selected countries.

   Discussion Top

The results of a hospital-based survey are not necessarily representative of the total population with eye disease; this is because the patients attending to the hospital are self-selecting. However, it can provide us with some perspective on pattern of eye diseases seen in the hospital relative to the total blind population.

We did not study cases of low vision and restricted our study to blindness, because we felt that patients with low vision may not seek medical advice while blind patients most probably will. This may make our study more nearly representative of the entire population of Yemen. Although this study cannot be taken as indicative of the whole situation in Yemen it tells us on the relative frequency of causes of blindness.


Cataract was found to be the main cause of uniocular (21.3 percent) and binocular blindness (46.3 percent) in Yemen which is a developing country that need to expand further medical and surgical facilities especially in rural area; this is similar to that found in other studies in developing countries. [3],[5] where it contributes to 57.7 percent of cases of blindness in India and Latin America, and was responsible for 45.2 percent in the Middle East crescent. [8] In Yemen as in other developing countries there is a common believe among most elderly that reduced vision is considered a normal aging process.


Glaucoma was the fifth most common cause of unilateral blindness (6.8 percent) and the second most common cause of bilateral blindness (10.4 percent). The prevalence of glaucoma in our population has not been studied but in a study conducted in a major hospital in Sana'a it was noticed that patients with glaucoma tend to present at a late stage as there is no screening program. [9] Many of the glaucoma patients presented very late with severe visual loss and typical disc changes hence, visual field assessment was not essential in reaching diagnosis in all cases.

Diabetic Retinopathy:

Diabetic retinopathy is the third cause of bilateral blindness (8.6 percent) and this is almost similar to other studies' figures in India. [5] Most studies in developing countries show that diabetic retinopathy is one of the leading causes of blindness preceded by cataract and glaucoma. [10]

Blindness caused by diabetic retinopathy has been decreasing worldwide since the introduction of laser photocoagulation and advances in vitreoretinal surgeries. [11] Vitreoretinal services is not well established in most developing countries and if available, it is expensive to the majority of patients. Late presentations of diabetic retinopathy patients still hang on to a concept between Yemeni patients that they may loose vision if they receive laser treatment early. Other patients who receive laser treatment think they have become immune to further progression of the diabetic retinopathy and start neglecting the control of their diabetes. [12]

Age Related Macular Degeneration:

Age related macular degeneration (ARMD) is the leading cause of blindness in western countries. [13] This is not the case in our study and in neighboring countries where it was found to be the fourth cause of bilateral blindness (8.1 percent). Results from community based survey revealed a high prevalence of ARMD (in age 50 years and above) as a cause of blindness (14.3 percent). [6] Possible explanations are the lower life expectancy of our population compared to Western countries, and the high prevalence of illiteracy among the elderly who do not appreciate loss of central vision needed for reading.

Corneal Opacity:

The importance of corneal opacification as a cause of blindness varies. It depends on the triggering factors for opacification in any individual. [14] In our study we included opacities caused by bacterial and viral infections, dystrophies, those complicating trichiasis and entropion or other causes apart from ocular injuries and keratoconus. Corneal opacities was found to be the third most common cause of unilateral blindness (11.5 percent) and the fifth most common cause in bilateral blindness (6.3 percent). Corneal donations are not available in Yemen and there is a long waiting list of patients in need of corneal grafts.


Trauma is a common cause of blindness in developing countries. In Yemen trauma was found to be high compared to some published studies in neighboring countries and that is related to stone and stick related injuries, road traffic accidents, landmines, bomb explosions and fireworks. [17] In our study trauma related ocular complications was found to be the second most common cause of uniocular blindness responsible for 20.2 percent. In Jordan it was responsible for 11 percent, [10] while in Lebanon was responsible for 5 percent [15] and in Cambodia was responsible for 13 percent. [16] Unfortunately there is no corneal and vitreoretinal subspecialty services at the time of conducting this study leading to most cases having corneal and posterior segment lesions that ended with blindness.[20]

   References Top

1.Republic of Yemen, Ministry of Planning and Development, Central Statistical Organization. Statistic Yearbook, 2000.  Back to cited text no. 1    
2.Republic of Yemen, Ministry of Planning and Development. Yemen: Human Development Report, 2000/2001.  Back to cited text no. 2    
3.World Health Organization. International statistical classification of diseases and related health problems, tenth revision (ICD 10). Vol 1. Geneva: WHO, 1992.  Back to cited text no. 3    
4.Ministry of Health. Family Health Survey July 2003, Yemen.  Back to cited text no. 4    
5.Foster A. Global Blindness and Vision 2020 - the right to sight. Saudi Journal of Ophthalmology, 2002;16(4): 275-278.  Back to cited text no. 5    
6.Al-Mohammadi K. Prevalence of low vision and blindness in age group 50 years and above in Hethran subdistrict, Taiz, Yemen. (MSc Thesis). Pakistan Institute of Community Ophthalmology, Peshawar, Pakistan. October 2002.  Back to cited text no. 6    
7.Gorafi I. Blindness Prevention Work in Yemen. Presented at American Academy of Ophthalmology, USA, 1998.  Back to cited text no. 7    
8.Thylefors B, Negrel AD, Pararajasegaram R, Dadzie KY. Global data on blindness. Bull WHO 1995;73:115-121.  Back to cited text no. 8    
9.Bamashmus M, Al-Shabooti A. Is surgical Management of Cataract and Glaucoma Patients in Yemen Changing? Saudi Medical Journal 2004;25(4):535-536.  Back to cited text no. 9    
10.Al-Bdour M, Al-Till M, Abu-Khadher I. Causes of blindness among adult Jordanians: A hospital-based study. Eur J Ophthalmol 2002;12:5-10.  Back to cited text no. 10    
11.Ubig M, Hamilton A. Factors influencing the natural history of diabetic retinopathy. Eye 1993;7:242-9.  Back to cited text no. 11    
12.Bamashmus M, Al-Akily A, Gunaid A. Diabetes and Blindness in Yemen. Presented at Second Yemeni Diabetic Association Conference, Sana'a, 11-13 October 2004.  Back to cited text no. 12    
13.Bamashmus MA, Mathlaga B, Dutton GN. Causes of blindness and visual impairment in the West of Scotland. Eye 2004;18:257-261.  Back to cited text no. 13    
14.Narita AS, Taylor HR. Blindness in the tropics. Med J Austr 1993;159:416-420.  Back to cited text no. 14    
15.Mansour AM, Kassak K, Chaya M, Hourani T, Sibai A, Alameddin MN. National Survey of blindness and low vision in Lebanon. Br J Ophthalmol 1997;81:905-906.  Back to cited text no. 15    
16.Thomson I. A Clinic-based survey of blindness and eye disease in Cambodia. Br J Ophthalmol 1997;81:578-580.  Back to cited text no. 16    
17.Al-Shabooti A, Bamashmus M. Profile of Ocular Trauma in Sana'a, Yemen. Saudi Journal of Ophthalmology, 2002;Vol 16(3):195-198.   Back to cited text no. 17    
18.Haddadin A, Ereifej F, Zawaida F, Haddadin H. Causes of visual impairment and blindness among the middle-aged and elderly in northern Jordan. Eastern Mediterranean Health Journal 2002;8(2-3):404-408.  Back to cited text no. 18    
19.El-Gilany AH, El-Fedawy S, Tharwat M. Causes of blindness and needs of the blind in Mansoura, Egypt. Eastern Mediterranean Health Journal 2002;8(1):6-17.  Back to cited text no. 19    
20.Herse P, Gothwal VK. Survey of Visual impairment in an Indian tertiary eye hospital. Indian Journal of Ophthalmology 1997;45(3):189-193.  Back to cited text no. 20    


  [Table 1], [Table 2], [Table 3], [Table 4]


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