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Annals of African Medicine
Annals of African Medicine Society
ISSN: 1596-3519
Vol. 6, Num. 4, 2007, pp. 180–185
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Annals of African Medicine, Vol. 6, No. 4, 2007, pp. 180 – 185
Pattern
of Presentation and Outcome of Surgical Management of Primary Open Angle
Glaucoma in Kano, Northern Nigeria
A.Lawan
Department
of Ophthalmology, Faculty of Medicine, Bayero University Kano, Nigeria
Reprint
requests to: Dr. Abdu Lawan, Department of Ophthalmology, Aminu Kano Teaching
Hospital, Kano, Nigeria. E-mail: lawal1966@yahoo.com
Code Number: am07040
Abstract
Background: Primary
open angle glaucoma (POAG) is one of the leading causes of avoidable blindness.
Unlike blindness from cataracts, glaucomatous optic nerve damage is
irreversible, and prevention of glaucoma is one of the priorities of World
Health Organization (WHO) Vision 2020 program. POAG is the commonest type of
glaucoma and affects about 33.1 million people worldwide. This study is a five
year review of 71 eyes of 63 patients who had trabeculectomy. The study
evaluates the pattern of presentation and modality of surgical treatment in our
environment.
Methods: Records of
all patients with primary open angle glaucoma operated over a five year period
was retrieved. Information extracted included patients bio data, visual acuity,
gonioscopic findings, intra ocular pressure as measured with applanation
tonometer before and after surgery, and recorded in mmHg. Perimetry was done
with 2 m tangent screen and recorded in a perimetry chart. All the patients had
trabeculectomy with application of anti metabolite (5fluorouracil). Extra
capsular cataract extraction with or, without posterior chamber intra ocular
lens implantation was done on 13 patients. Biometry was not done on patients
with cataract. Surgery was done on better eye first in all patients.
Results: There were
71 eyes of 63 patients. The male to female ratio was 3:1. The age ranged
between 18 to 75 years. 8 patients were below the age of 30 years. One third of
the patients were between the ages of 50 to 59 years. At presentation 12
patients (19%) had normal vision (WHO vision category O), 26 patients (41%)
were visually impaired, 12 patients (19%) were severely visually impaired and
13 patients (21%) were blind (from co existing cataracts). The cup disc(c: d)
ratio assessed before surgery was 0.5 in 9 eyes (13%), 31 eyes (53%) had c: d
ratio 0.6 to 0.8 and 18 eyes had c: d ratio of 0.9. All the patients had open
anterior chamber angles (Schafer grade 3 and 4). Perimetric changes were; mild
peripheral constriction in 5 eyes (8%), peripheral constriction with arcuate
scotoma in 19 eyes (26%), constricted fields of 30° or less in 34 eyes (48%),
and in 13 eyes there was inability to fixate on target. IOP before surgery was
21 to 30 mm Hg in 12 eyes (17%), and above 31 mm Hg in 69 eyes (83%). Post
operative IOP of 10 to 15 mm Hg was obtained in 58 eyes (82%) and 11 eyes (15%)
had IOP of 16 to 20 mm Hg. Only 2 eyes (3%) had IOP in the lower twenties.
Conclusion: Primary
open angle glaucoma is characterized by late presentation. Trabeculectomy with
application of 5FU is the surgical treatment of choice in our environment and
give good intra ocular pressure control. There is need to increase public
awareness on glaucoma to limit this type of avoidable blindness.
Key words:
Glaucoma, late presentation, avoidable blindness,tTrabeculectomy
Resume
Introduction: Angle douverture du glaucome primaire (AOGP)
est lune des causes principales de la cécité évitable. Contrairement à la
cécité de la cataracte dégât au glaucomateuses nerf optique est irréversible,
et prévention du glaucome est lune des priorités de lOrganisation Mondiale de
la Santé (OMS), programme du Vision 2020, AOGP est le type de glaucome le plus ordinaire
et touche environ 33,1 million de personnes dans le monde. Cette étude est un
bilan dune durée de cinq ans de 71 yeux de 63 malades qui étaient atteints du
trabeculectomie. Cette étude fait une évaluation de la tendance de présentation
et les modalités du traitement chirurgical dans notre milieu.
Méthodes: Les dossiers médicaux des patients atteints
dangle douverture du glaucome primaire opérés sur une période de cinq ans ont
été récupérés. Des informations retirées comprennent des données biologiques
des patients, lacuité visuelle, des résultats gonioscopiques, la pression
intra oculaire mesurée avec tonométrie applanation avant et après
lintervention chirurgicale, et enregistré en mmHg. La périme trie a été
effectuée avec 2 mètres écran tangent et notés dans un tableau périme trie.
Tous les patients avaient eu la trabéculectomie avec une application
danti-métabolite (5fluorovracil). Extraction de la cataracte Extra capsulaire
avec ou, sans chambre intraoculaire lentille postérieure dimplantation a été
opérée sur 13 patients. La Biométrie na pas été fait sur les patients atteints
de la cataracte. La chirurgie a été opérée sur un meilleur il dabord dans
tous les patients.
Résultats: Il y a eu 71 yeux de 63 malades. Le rapport du
sexe masculine/sexe féminin était 3:1. Lâge variait entre 18 et 75 ans. 8
patients étaient âgés de moins de 30 ans. Un tiers des patients étaient âgés de
50 à 59 ans. Lors de la présentation 12 des patients soit 19% avaient une
vision normale (OMS vision de la catégorie O), 26 malades soit 41% étaient
malvoyants, 12 soit 19% ont été gravement malvoyants et 13 patients soit 21%
étaient des aveugles (des cataractes co-existantes). La coupe disc- c (d: d) du
rapport évalué avant lintervention chirurgicale était 0.5 dans 9 yeux soit
13%, 31 yeux soit 53% avaient le rapport c.d de 0,6 au 0,8 et 18 yeux avaient
le rapport de 0,9. Tous les patients avaient eu langle ouvert de la chambre
antérieure (schafer de grade 3 et 4), changements périme triques étaient: doux
périphériques de constriction dans 5 yeux soit 8%, constriction périphériques
avec arquées scotome dans 19 yeux soit 26%, limites domaines du 30o ou moins en
34 yeux soit 48%, et dans 13 yeux, il était impossible de viser sur lobjectif.
IOP avant la chirurgie était 21 à 30 mmHg dans 12 yeux soit 17% et au dessus de
31 mmHg dans 69 yeux soit 83%. IOP post opératoire de 10 à 15 mmHg a été
obtenue dans 58 yeux soit 82% et 11 yeux soit 15% avaient IOP de 16 à 20 mmHg.
Deux (2) yeux seulement soit 3% avaient eu IOP dans la basse vingtaine.
Conclusion: Langle douverture du glaucome primaire est
caractérisée par une présentation tardive. La trabeculoectomie avec
lapplication du 5Fu est un traitement chirurgical de choix dans notre milieu
et donne de bons contrôles intracommunautaires de la pression oculaire. Il est
nécessaire de mieux informer le publique sur le glaucome afin de diminuer ce
type de la cécité évitable.
Mot clés: Glaucome,
présentation tardive,la cécité évitable, trabeculectomie
Introduction
Primary
open angle glaucoma (POAG) is generally bilateral, although not necessarily
symmetrical disease characterized by; glaucomatous optic nerve damage,
glaucomatous visual field defects, adult onset, open and normal appearing
anterior chamber angles, repeated intra ocular pressure (IOP)>21 mm Hg at
some point in the disease (although 15% or more of those with otherwise
characteristic POAG will have IOP consistently below 21mmHg and are referred to
as having normal tension glaucoma), and absence of secondary causes of open
angle glaucoma. POAG is the most prominent of all glaucomas and occurs in 1 in
200 people above the age of 40years.1 Glaucoma is one of the leading causes of blindness worldwide.2-4 In a population survey of Dambatta district of Kano state, 15% of those blind
and 7% of those severely visually impaired had glaucoma.5 POAG
is commoner in blacks as it occurred in 1 in 11 people above the age of 50
years, and 1 in 6 above the age of 70 years.6
This study is a retrospective review of 71 eyes of 63 patients
operated for primary open angle glaucoma in our hospital between June, 2001 and
June, 2006. The aim of the study is to evaluate the pattern of presentation and
outcome of surgical management of POAG in our environment.
Patients and Methods
Records
of all patients operated for POAG were retrieved. Information extracted
included age, sex, family history of glaucoma, myopia and power of the
correction, presence of systemic hypertension, and diabetes mellitus. Visual
acuity as measured with Snellens or, Illiterate C charts and recorded for
each eye. All patients had basic eye examination. Cup: disc (c: d) ratio was
assessed with direct ophthalmoscope. Intra ocular pressure was measured with
the applanation tonometer. All patients had indirect gonioscopy using Goldman
gonio lens. Perimetry was done with the 2 m Tangent screen using a 5 mm white
target and recorded on a perimetry chart. Intra ocular pressure was reduced to
at least upper twenties with oral acetazolamide and timolol 0.5% eye drops, before
surgery.
All the patients had trabeculectomy with application
of 5-fluorouracil (5FU). The procedure included cleaning and draping,
application of lid speculum, application of superior rectus bridle suture using
4/0 silk. Limbal based conjuctival flap was raised. Hemostasis was secured with
bipolar cautery. A tiny piece of cotton wool soaked with 5% 5FU was applied
over the site of the scleral flap; the conjunctival flap was reflected over the
cotton wool and allowed to stay for 5 minutes. The cotton wool soaked with 5FU
was then removed and area washed with 50 mls of normal saline. 5 x 5 mm outer
scleral flap was measured with caliper and raised; an inner triangular flap of
3X3 mm was raised and excised. Peripheral iridectomy was done. Outer flap was sutured
back at four edges using 9/0 silk suture. Anterior chamber was reformed with
saline when necessary. For those with associated cataracts, after excision of
inner scleral flap, visco elastic material was injected into the anterior
chamber (A/C). This was followed by can opener capsulotomy. The limbal incision
was extended on either side of the outer scleral flap edge. Nucleus was
delivered by vectis extraction.
This was followed by irrigation and aspiration of lens cortex. Visco was re
introduced in to the A/C and posterior chamber intra ocular lens (power of
either +19 or, +21 -based on availability) inserted and rotated into position.
Dialing was done when required. A peripheral iridectomy was done. The Outer
sclera flap was sutured as above and additional interrupted sutures applied on
either side of the flap to ensure closure of the corneo scleral incision. Any
remaining viscoelastic material was aspirated with Symcoe double cannula. The
conjunctiva flap was closed with 6/0 Vicryl®.
Patients were placed on topical Mydriacyl,
dexamethasone, and Lomefloxacin eye drops four times a day and discharged after
3-5 days. A time interval of 6 to 8 weeks was observed between first and second
eye. The eye to be operated first was the better eye in all patients.
Results
There
were 71 eyes of 63 patients, 47 males and 16 females giving a male to female
ratio of 3:1. The age ranges between 18 years and 75 years (see Table 1).
8 patients (13%) were below the age of 30 years. Peak age group at presentation
was between 50 to 59 years. 20 patients (32%) fell into this category. 12
patients (19%) had visual acuity of 6/6 -6/18 before and after surgery. This is
World Health Organization (WHO) vision category O.7Table2shows
that the number of patients with vision category 1 increased from 41% to 51%.
Those with vision category 2 increased from 19% to 29%. Number of patients with
category 3 vision reduced from 21% to 1% after surgery. 9 eyes (13%) had cup:
disc (c: d) ratio equal to or less than 0.5, 31 eyes (54%) had c: d ratio of
0.6 to 0.8 and in 18 eyes (33%) the c: d ratio was 0.9. The c: d ratio could
not be assessed before surgery in 13 eyes (18%) due to cataract. In this group
the c: d ratio was found to be 0.6 to 0.8 in 7 eyes, and 0.9 in 6 eyes. The
intra ocular pressures at presentation are shown in Table 3. 12
eyes (17%) had IOP 30 mm Hg and below, 55 eyes (77%) had IOP 31 to 50 mm Hg,
only 4 eyes had IOP above 50 mm Hg at presentation. Results of perimetry as
demonstrated in Table 4 showed that 5 eyes (7%) had
peripheral field constriction of 10-20.o 19 eyes (27%) had both
peripheral field constriction and arcuate scotoma, 34 eyes (48%) had visual
fields of 30° and less. In 13 eyes (18%) there was in ability to fixate on the
target. All patients had open anterior chamber angles on gonioscopy (Shaffer
grades 3 and 4). That is anterior chamber angle structures visualized up to
scleral spur. Fifty five patients (87%) had surgery in one eye (the better eye)
and only 8 patients (13%) had surgery in both eyes. 7 out of 8 patients in this
group were below the age of 40 years. There were 39 right eyes and 32 left
eyes. 50 patients (79%) had trabeculectomy alone, 12 patients (21%) had
trabeculectomy and extra capsular cataract extraction plus posterior chamber
intra ocular lens implantation (ECCE+ PC IOL). The power of PC IOL was either
+19 or, +21 diopter sphere. One patient with myopia using minus 15 diopter
sphere correction presented with cataract and glaucoma and had trabeculectomy,
extra capsular cataract extraction without intra ocular lens implantation. This
patient developed posterior capsular opacity at 13-month and Yag capsulotomy
was done elsewhere. Biometry was not done in all the patients with cataract.
Post
operative IOP of 10 to 15 mm Hg was obtained in 58 eyes (82%), and 11 eyes
(15%) had IOP 16 to 20 mm Hg, only 2 eyes (3%) had IOP in the lower twenties
after surgery. Common immediate post operative complication noted was shallow
anterior chamber with positive Siedels test in 5 eyes (7%). This improved with
pressure padding. No post operative endophthalmitis recorded. Patients who had
trabeculectomy and cataract surgery developed corneal edema with marked
anterior chamber inflammation in 9 out of 13 eyes. 3 eyes developed cataracts
within 12 to 18 months after surgery and had an uneventful ECCE + PC IOL using
superior corneal approach. Only 5 patients (8%) admitted family history of
glaucoma.
Twelve
patients (19%) had associated medical illnesses. Seven had systemic
hypertension well controlled on medication, 3 had adult onset (type 2) diabetes
mellitus on oral agents for a range of 5 to 10 years. Two patients had both
systemic hypertension and diabetes mellitus with poor glucose and blood
pressure control.
Table 1. Age and sex
distribution of 63 patients with primary open angle glaucoma
Age
in years |
Sex |
Total |
% |
Male |
Female |
<19 |
4 |
1 |
5 |
8 |
20-29 |
3 |
- |
3 |
4 |
30-39 |
10 |
- |
10 |
16 |
40-49 |
6 |
- |
6 |
10 |
50-59 |
13 |
7 |
20 |
32 |
60-69 |
8 |
6 |
14 |
22 |
70+ |
3 |
2 |
5 |
8 |
Total |
47 |
16 |
63 |
100 |
Table 2. Visual status before
and three months after surgery
*WHO
Vision category |
Before surgery |
After surgery |
No. (%) |
No. (%) |
0 (Normal) |
12 (19) |
12 (19) |
1 (Visually impaired) |
26 (41) |
32 (51) |
2 (Severely visually impaired)
|
12 (19) |
18 (29) |
3 (Blind) |
13 (21%) |
1 (1) |
Total |
63 (100) |
63 (100) |
*
WHO vision category: 0 = 6/6-6/18, 1 = <6/18-6/60, 2 = <6/60-3/60, <3/60-NPL
Source:
Manual of international statistical classification of diseases, Injuries and
causes of death. Geneva. 1977; 46
Table 3. Intra ocular pressure
reading of 71 eyes of 63 patients at presentation
IOP in mmHg |
No. of eyes (%) |
21-30 |
12 (17) |
31-40 |
26 (36) |
41-50 |
29 (40) |
50+ |
4 (7) |
Total |
71 (100) |
Table 4. Perimetry findings in
71 eyes of 63 patients with primary open angle glaucoma
Visual fields defect |
No. of eyes (%) |
Peripheral constriction (mild) |
5 (8) |
Above + Arcuate scotomas |
19 (26) |
Constricted fields 30° or less |
34 (48) |
Unable to fixate on target |
13 (18) |
Total |
71 (100) |
Discussion
Primary
open angle glaucoma (POAG) is three times more common in males than females. 45
patients (71%) were above the age of 40 years in agreement with the pattern in
other parts of the world.1 8 patients (13%) were in their
first three decades of life. These belonged to the group of patients with
juvenile open angle glaucoma (JPOAG).8 JPOAG
accounts for 0.02% of all glaucomas.9 Over
the 5-year study period in review, trabeculectomy accounted for 12% of all
surgeries done in our hospital. A population survey in Dambatta local
government area of Kano state (where our hospital is located) showed that 15%
of those found to be blind had glaucoma.5 Glaucoma is one of the leading causes of blindness worldwide.2-4
Glaucoma is always under reported in surveys probably
due to different criteria used in definition, testing method used and criteria for
making a diagnosis of POAG.10 Of an estimate of 66.8
million affected, 33.1 million have POAG.11 Most population survey reports indicate that the disease is commoner in blacks
than whites12 and progresses more rapidly
in blacks.13 Unlike blindness from
cataract, glaucoma blindness is irreversible.14,15 The number of patients SVI or blind reduced due to the change in vision status
of the 13 patients who presented with cataracts and glaucoma. This patients
vision improved from blind (category 3) to visually impaired and SVI
categories. 1 patient remained blind due to associated long standing
chorioretinal scar involving the macular area. POAG affects the quality of life
of the individual.16
Our patients presented late. Even those who presented
earlier and despite intense effort at health education on the nature of the
disease, it was difficult to convince some patients that the eye that can see
far well has a potentially sight threatening disease. Many factors, some
racially inclined contribute to a more aggressive pattern of POAG in blacks.
One third of the patients had c: d ratio of 0.9 at presentation. Bowing of the
lamina cribrosa is featured as cupping of the optic disc.17 At
any given intra ocular pressure level greater pressure is exerted on large rather
than small optic discs.2,18 Large optic disc have been
observed in normal,18,19 post mortem20 and glaucomatous eyes of blacks.21
The IOP at presentation was high in most of the
patients. Greater optic nerve damage occurs in blacks than white eyes with same
level of IOP.22 Most of the patients had
significant visual field loss at the time of presentation. Blacks of all ages
tend to have worst visual fields than whites when 60° Humphreys visual field
was tested.23 Progression of visual field
loss is higher in blacks than whites.13 The
most important risk factors for glaucoma are age, elevated IOP, and family
history whereas diabetes mellitus, systemic hypertension and refractive errors
are potential risk factors.24 Positive family history of
glaucoma was obtained in only 5 patients (8%). This is not unusual in our
environment due to lack of awareness, poor record keeping of medical illness
and that most ailments are ascribed to bewitchment and superstition. In
developed countries, 50% of POAG and 43% with ocular hypertension have a
positive family history.25 Only 1 patient had high
myopia (-15 diopter sphere). Myopia is a mild risk factor for glaucoma.26 There is a positive relationship between high myopia and optic disc size.27 12 patients (18%) had associated medical illnesses. 7 had systemic
hypertension, and 3 had type 2 diabetes mellitus, 2 had both diseases. Rubeosis
iridis as eye complication of diabetes can cause secondary glaucoma.28
None of
these patients had neo-vascularization. Systemic hypertension may accelerate
glaucoma damage due to vasoconstriction and closure of small vessels.29 Some studies suggested that at the initial stage of systemic hypertension, the
high arterial pressure improves optic nerve perfusion and by so doing offers
50% reduction of POAG mediated damage to the optic nerve at 4 years follow up.30 It is often agued the justification for surgical management of POAG.
Effectiveness of most anti glaucoma medication is assessed in white rather than
black populations.31 Newer, safer, more effective,
more tolerated drugs are not available to our patients.32 Some studies suggest that medical treatment is less beneficial in blacks than
whites33 and blacks respond less to
medical treatment than whites.22
In healthy Nigerians, IOP lowering effect of timolol
peaked rapidly and faded away in 6 hours34 unlike the sustained effect in whites.35 Higher concentration of the same drug is required in blacks. Possibly, the drug
binds to melanin in ocular tissues such that only a small amount is available
to reduce IOP.36 Glaucoma medicines are not
easily available to our patients in rural areas.37,38 Most patients are poor and where these drugs are available they are fake and
ineffective. Medical treatment is expensive and compliance is poor. There is
long distance between patient and ophthalmologist.39 Patient wants visual restoration and eye drops do not restore lost vision40 and neither does surgery. It is evident that racial factors play a role in
response to treatment modality.41 In our study IOP
was 10 to 15 mm Hg in 58 eyes (82%) during a follow up period of 6-month to 5
years. Anti fibrotic agent such as 5FU may increase the success of
trabeculactomy.42 Surgery is not risk free as
it accelerates cataract formation, and there is risk of visual wipe out
phenomenon in those with constricted fields. It does not restore lost sight
against the patients expectation. Argon laser trabeculoplasty (ALT) may have
lower long term IOP lowering effect in blacks than whites.43 Blacks have higher risk of ALT failure than whites.44 In
any case lasers are hard to come by in our setting..
Many ophthalmologists in Africa are frustrated and
avoid glaucoma surgical treatment.37 Cataract, trachoma, onchocerciasis and childhood blindness have committed non
governmental organizations (NGOs) with established programs to control these
causes of blindness. Glaucoma has no NGO. There is need to increase public
awareness of glaucoma with the aim of early detection and intervention. Doctors
in general practice should be encouraged to do fundoscopy and identify optic
disc cupping and refer suspected cases to ophthalmologists as part of their
normal duties. Government needs to provide policy guideline and funding for
local training and research on appropriate glaucoma management.
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