Set as Homepage
Glaucoma Disease Patterns in Pakistan
 
Introduction
Glaucoma is estimated to be the third most prevalent cause of blindness in the world, after cataract and trachoma. Blindness due to glaucoma is irreversible and has many socio-economic consequences for society in terms of treatment cost and loss of productive working hours.
 
Glaucoma is not a single entity but a group of diseases that differ in clinical presentation, pathophysiology and treatment. In a study done in Lahore, 23% of blindness was found to be due to glaucoma ( all types)3. However, this study does not give details of the different types. A retrospective study based on the data available at the glaucoma clinic of the Al-Shifa Trust Eye Hospital, Rawalpindi, found the relative incidence of different types of glaucoma in the Pakistani population, as shown in table 1.6
 
Discussion
Glaucoma comprises a group of ocular disorders that cause progressive excavation of the optic disc. Optic atrophy and a characteristic loss of visual field, which can be arrested or moderated by adequate reduction of intraocular pressure. Glaucoma is classified as open angle or angle closure type, according to the manner in which aqueous out follow is impaired. Further, classification describes the condition as primary or secondary, congenital or adult.5The incidence rate and prevalence of glaucoma in Pakistan is similar to that of dark-coloured people in developing countries, although concrete statistical evidence is lacking. Pakistan is a melting pot of all races_____ not only are racial mixtures of all societies seen, but groups such as Caucasians, Africans, and Mongol and Chinese populations are also seen in their pure form.
 
Historically, this part of the world was once inhabited by the Aryan races. Since there is such a mixture of races, it is not possible to generalise the expected aetiology, pathology and response to treatment for the people of Pakistan.  Only long-term studies involving large numbers of patients can produce some answers. These studies must also incorporate patient’s complexion and facial features in order to gain an insight into the racial effect.
 
Studies are currently being performed to evaluate the particular anatomical features of the eyes of the people of Pakistan and to record the normal range intraocular pressure (IOP): C/D ratio mean neuroretinal rim area, refractive status and axial length. These studies are yet to be completed and only a faint picture can be painted at the moment. However, a review of these studies and detailed discussions with experienced ophthalmologists have brought some facts to light.
 
Table 1. percentage incidence of glaucoma6
 

 
 
Sr. No Types of glaucoma No of patients Percentage
1. POAG  2482 42%
2.   PACG 1005 17%
3.  Aphakic glaucoma 767 13%
4. Secondary glaucoma 266 4.5%
5. Glaucoma capsulare 342 5.8%
6. NTG 177 3.0%
7. Buphthalmos 171  2.9%
8. Glaucoma suspects 696 11.8%
  Total  5906   100%
Abbreviations: POAG = primary open angle glaucoma: PACG = primary angle closure glaucoma: NTG = normal tension glaucoma
There is a higher incidence of smaller axial lengths leading to hyperopia, shallow chambers and increased incidence of narrow angle glaucoma in Pakistan. The ratio between males and females for narrow angle glaucoma is the same as elsewhere (i.e. 1:4), but patients with primary open angle glaucoma (POAG) also have shallow chambers and must be properly investigated by gonioscopy by a trained ophthalmologist. The Zeiss lens is absolutely essential for our patients because the Goldmann lens cannot produce indentation and, most of the time, gives a false impression of closed angles in the horizontal meridian, even when the angle is open all round. The incidence of pigmentary glaucoma is rare although most people have pigment deposition in the trabecular meshwork. The lamellar slit sign has proved to be a reliable indicator of field loss in our patients.
 
The following facts have been ascertained in patients with glaucoma in Pakistan.
  • The incidence of pseudoexfoliation and associated glaucoma is comparable to that of the population in the USA.
  • The normal range of IOP varies from 10 to 18 mm Hg on applanation. 
  • There is a much higher incidence of normal tension glaucoma, which goes unrecognized, as proper visual fields are not always done and patients are dismissed as having large physiological cups.
  • The average age of a patient with POAG is 40 to 50 years with a significant number of patients aged below 40 years. The youngest patient is enrolled in an ongoing study by Kaisser, and is 18 years old. The incidence of POAG in younger populations is comparable to that of blacks in the USA and elsewhere.
  • A significant number of patients present with either almost complete blindness in both eye or blindness in one eye and useful vision in the other. This state of affairs is because of a lack of education and health awareness, and because of a lack of trained eye care personnel.
  • Diabetes and hypertension make the disc more susceptible. Many patients with glaucoma and diabetes mellitus or hypertension are poorly controlled. Therefore, their field loss rapidly progresses despite better control of IOD.
  • Glaucoma patients respond to topical drugs such as B-blockers, pilocarpine and dipivefrin. The pressure decrease attained from these drugs is similar. Usually 5 to 7 mm Hg. Topical dorzolamide is used only in selected cases because of its prohibitive cost. The combination of B-blocker and pilocarpine has the maximum pressure lowering effect, usually in the range of 20 mm Hg. Surgeons generally start treatment with B-blockers and add other drugs if the pressure is not lowered to the desired limit. Oral acetazolamide is given only for short periods.
Although 50% of patients report side effects of these drugs, the commonest reason for stopping medication is financial. Other causes include lack of understanding of the disease and a search for other avenues of treatment such as Hakims and quacks.
 
  • Follow-up is the largest problem in Pakistan. Patients lack understanding of the importance of follow-up in the treatment of their disease.  Socioeconomic and environmental factors also play their part. It is because of lack of follow-up and compliance for medical therapy that almost all surgeons favour early surgery for their patients.Trabeculectomy is the preferred operation. A review of operation lists in  different eye hospitals has shown that 1 of 10 operations is glaucoma surgery.
  • Argon laser trabeculoplasty (ALTP ) has a very limited role in this population ( unpublished data). Immediate postlaser rise of IOP is a cause for concern for the patient, while a high failure rate precludes its frequent use.
  • One of every 4 glaucoma filtration patients has closure of the inner window within 5 years of surgery (unpublished data). These patients are retreated with antimitotic drugs. The latest results are awaited
The incidence of congenital and juvenile glaucoma is comparable to that of studies in the USA but definitive results cannot be quoted.
 
In Conclusion
Glaucoma occurs worldwide, and Pakistan is no exception. Particular circumstances in Pakistan, such as illiteracy, poverty, and lack of medical facilities and personnel, dictate the line of management for the average patient.
 
References
  • Foster A. Patterns of blindness. In Tasman W. Jaeger EA, leds, Duane’s clinical ophthalmology. Philadelphia: JP Lippincott, 1990:5-7.
  • Dunbar Hoskins H. Jr. Kass MA. In: Becker-Shaffer’s diagnosis and therapy of the glaucomas 6th ed. St. Louis: The CV Mosby Company. 1989:2-3.
  • Jehangir S. A survey of blindness in eye patients in Punjab Pak J 
    Ophthalmol 1993;9:43-45    .
  • Newell FW, Ophthalmology, principles and concepts 7th ed.St. Louis. Mosby Year Book Inc, 1992:368-389.
  • Kanski JJ. Clinical ophthalmology, 2nd ed. Butterworth—Heinemann. International, 1998:181-231
  • Nawaz Malik M. Relative incidence of different types of glaucomas in Pakistan. Al-Shifa Medical Bulletin 1995.1.4-5
 
Return to Online Articles