“Don’t Let Glaucoma Darken your life”

World Glaucoma week was observed from March 11 – 17, 2012 under the theme “Don’t let glaucoma darken your life”.  On World Glaucoma Day, March 15, Dominica News Online published an address under the same title by Minister for Health,  Julius Timothy.  DNO is continuing the process of educating the public on this important disease,  by publishing this more comprehensive article by Consultant Opthalmologist, Dr. Hazel Shillingford-Ricketts. 

Globally it (glaucoma) is the second leading cause of blindness after cataracts, but it poses a greater public heath challenge as blindness from glaucoma is irreversible and as the world’s population ages the number of persons with glaucoma will increase. It is the leading cause of irreversible blindness. In 2006 it was estimated there were about 67 million people with glaucoma and 10% of them were blind.

In the Caribbean region including Dominica glaucoma is one of the five preventable causes of blindness listed in their Vision 2020 “the right to sight” strategy to eliminate preventable causes of blindness by the year 2020.

Glaucoma is defined as a progressive damage of the optic nerve associated with characteristic loss of visual field. The optic nerve transmits the visual image from the eyeball to the brain. The primary visual cortex in the brain is responsible for vision.

Glaucoma cannot be cured but it can be controlled. It is life-long and non-infectious. Hence it can be classified as a chronic non-communicable disease,

Untreated glaucoma results in irreversible blindness and the affected person is subjected to live in a world of complete darkness for the rest of their life. Hence the theme for this year’s Glaucoma Week: ‘Don’t Let Glaucoma Darken Your Life.’ However blindness from glaucoma can be prevented.
There are several types of Glaucoma. The most common type is primary open angle glaucoma. This type is most prevalent among Black people with 6-8 times the risk of Caucasians.
The other types of glaucoma are primary close angle glaucoma, secondary glaucoma and developmental glaucoma. One of the causes of developmental or congenital glaucoma and blindness among children is Rubella. However due to our excellent immunization coverage in Dominica Rubella infection has been eliminated.

The risk factors for open angle glaucoma are aging, family history of glaucoma,
raised intraocular pressure, myopia or near-sightedness and diabetes mellitus.

Epidemiology

The Barbados eye study conducted 1987-1992 in a population of predominantly black people age 40 -84 and the Barbados Incidence Study of Eye Diseases (BISED I, 1992-1997) has provided data about glaucoma in black people.
The prevalence of open angle glaucoma was found to be one out of eleven for persons 50 years and older increasing to one out of six for persons 70 years and older. The prevalence was higher among men 8.3% compared to 5.7% in women.
The four year incidence of open angle glaucoma for age 40 or older was 2.2%. The incidence increased with age: 1.2% for age 40-49 increasing to 4.2% for age 70 years or older.
The 9-year incidence was 1.0% and 2.1% for blindness by WHO and US criteria, respectively in the Barbados cohort.
When these rates are applied to the 40-84 age group population of Dominica
(2001 census), the following numbers reflect the burden imposed on the public health service by open angle glaucoma.

It is estimated that there are over 1517 persons between the ages 50 -84 with open angle glaucoma in Dominica. Hence we expect the actual number for the over 40 age group to be greater. Every four years it is estimated that there will be 465 new cases of open angle glaucoma in the 40-84 age group.

Using the United States definition of blindness of the best-corrected visual acuity of less than or equal to 6/60 or 20/200 in the better eye, over a nine year period it is estimated that there will be 444 new cases of blindness in Dominica: The three leading causes of blindness with the estimated numbers are cataracts 214 (blindness from cataract is reversible with eye surgery), open angle glaucoma 62, diabetic retinopathy 39.
Blindness from glaucoma can also be defined as a constricted visual field of less than 10 degrees from fixation irrespective of the visual acuity. Such a person may have a visual acuity of 20/20.

About 50% of people with open angle glaucoma do not know that they have the disease.
About 50% of people with open angle glaucoma have intraocular pressures in the normal range of 10-22mmHg when the diagnosis is made. Therefore one cannot rely only on the intraocular pressure to make a diagnosis of open angle glaucoma. A person has to lose about 40 % of their visual field before they become symptomatic earning glaucoma the description of being the “silent thief of sight”.

Eye Evaluation and Treatment

A comprehensive eye evaluation begins with a careful medical history to determine the presence of risk factors.
The examinations are as follows:
The visual acuity: To determine the best-corrected vision
Pachymetry: The measurement of the corneal thickness
Gonioscopy: Measure the depth of the anterior chamber angle to determine whether the angle is open or closed
Funduscopy: To determine the extent of damage of head of the optic nerve called the optic disc.
Tonometry: Measure the intraocular pressure
Visual field test: Computerized measurement of the peripheral field or side vision

New technologies: Scanning Laser Tomography and Optical Coherent Tomography are non-invasive, objective, quantitative structural assessment of the optic disc and the retinal nerve fibres. These tests are used to determine loss of the nerve fibres and optic disc changes even before visual field loss can be detected.

Once the diagnosis of glaucoma is made treatment is started.
Treatment consists of eyedrops and tablets. A patient may be prescribed to use one or multiple eyedrops, up to four different eyedrops. If medical treatment with eyedrops and tablets fail to arrest the progression of visual loss, then surgery with laser or drainage procedures can be performed.

Glaucoma treatment is long term and the potential for adverse interactions increases with time and multiple eyedrops. The side effects impact negatively on the quality of life of the patients and adherence to treatment.
Non-adherence factors are multifactorial. The most commonly reported factors especially among the older patients are:
• Difficulty with eyedrops administration
• Paying for medication
• Reading the prints on the bottles of eyedrops
• Getting the seal off the bottle caps
• Squeezing the bottles to drop the medication in the eyes
• Side effects either from active ingredient or preservative
• Remembering to take the eyedrops

The benefits from glaucoma treatment are not readily apparent because visual loss is not reversed, just halted or slowed. Hence patients may be aware only of the negative aspects of treatment and find in the short term that they would rather not use their eyedrops to avoid the discomfort. This practice has serious and extensive consequences for glaucoma patients.

Visual loss is associated with adverse implications for health and well-being, including reduced quality of life, functional and cognitive decline, work and academic underperformance, anxiety, depression, inability to drive, reduced social interaction, increased frequency of falls and fractures, loss of independence leading to institutionalization or nursing home admission, and perhaps even higher risk of early mortality. It is not often recognized that the magnitude of adverse impact on functional status and well-being due to irreversible visual loss is comparable to that attributable to major medical conditions. Visual impairment and blindness also leads to increased direct and indirect costs at the individual and family level, as well as to increased costs to healthcare systems.

There are clear benefits to interventions that prevent or delay vision loss.

In Dominica patients can stop glaucoma from darkening their life because:

1. Eye care is accessible at Princess Margaret Hospital, Primary Health Districts and the Private Health Sector. Opportunistic screening for glaucoma is performed for all patients presenting for eye care.

2. It is affordable because eye care as other health services, is free for all age groups in the Primary Health Districts and for patient 18 years and younger and 60 years and older at Princess Margaret Hospital.

3. Eye care is available because there is a properly trained Board Certified Ophthalmologist and Ophthalmic Technicians employed in the Public Sector.

In the Private sector there are eye care services too.

All of the most efficacious eyedrops can be obtained. Some of the eyedrops not offered free of charge in the public sector are offered at cost price, almost 50% cheaper than in the private sector at the Central Medical Stores, Princess Margaret Hospital. Applications have been made for these eyedrops to be included in the government drug formulary so that they can be obtained free of charge throughout the Primary Health Districts. This will also remove the need for patients to travel to Roseau to purchase these eyedrops. However, this is estimated to cost an additional EC$300.000.00 per annum.

The most commonly used surgical treatments of Laser peripheral iridotomy and Trabeculectomy are offered in Dominica. Patients are referred overseas for the implantation of surgical devices when indicated and can be afforded by them.

Computerized visual field testing is available in the private sector.

Recommendations

1. Patients are advised from the age of 40 to have regular eye examinations.

2. Patients diagnosed with glaucoma should adhere to using their eyedrops as prescribed and keep their follow-appointments with their Eye specialist.
Relatives should assist patients diagnosed with glaucoma: helping to pay for the medications as needed, putting the eyedrops for them if this poses a challenge physically for the patients, reminding them of their appointments and providing transportation for their follow-up eye visits.

3. Relatives of patients with open angle glaucoma are at an increased risk of developing glaucoma. These relatives should have regular eye examinations from the age of 35.

4. Patients who sustained injury to their eyes and those who use any type of steroid medications over a long time are at risk for developing glaucoma and hence should have regular eye examinations.

In conclusion glaucoma, the silent thief of sight, can darken your life because it can cause irreversible blindness. It cannot be cured but it can be controlled. The earlier glaucoma is detected and treated the greater the chance of preventing blindness.

You have been informed! Don’t let glaucoma darken your life!

Submitted by Dr. Hazel M. Shillingford-Ricketts
M.B.B.S. (UWI); F.R.S.C. (C)
Consultant Ophthalmologist
The Brenda Strafford Eye Centre
Princess Margaret Hospital