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May, 2017 2017; Vol1; Issue4 http://iamresearcher.online
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
Opportunistic Screening for Glaucoma Amongst
Glaucoma Patients’ First Degree Relatives who
Accompanied them to Glaucoma Clinic
Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku
Department of Ophthalmology, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria
Corresponding Author: Godswill Inye Nathaniel
drnathy2013@gmail.com
ABSTRACT
Aim: To identify people with glaucoma and glaucoma suspect amongst first degree relatives accompanying their
glaucoma patient relatives to the Glaucoma clinic, University of Port Harcourt Teaching Hospital, Port Harcourt.
Materials and methods: It was a prospective population-based study of first-degree relatives of Primary open-angle
glaucoma patients who accompanied them to the glaucoma clinic. All participating individuals underwent
comprehensive eye examination including vision screening, refraction, slit lamp biomicroscopy, applanation
tonometry, gonioscopy and dilated fundus examination. Persons with definite and suspected glaucoma were subjected
to threshold standard automated perimetry. Results: A total of 95 individuals who were first-degree relatives of 41
patients with Primary open angle glaucoma were examined. Fifty-seven of them (60%) were males, and 38 (40%)
were females, with a mean age of 37.71± 8.15 years. Eighty-three (87.37%) were offspring and 12 (12.63%) siblings.
Eighteen (18.9%) were observed to have definite Primary open angle glaucoma; 7 (7.4%) of them had been previously
diagnosed. Another 16 (16.8%) of the relatives were found to be Glaucoma suspect. Twelve (66.7%) of those with
glaucoma were males while 6 (33.3%) were females;13 (72.2%) were offspring while 5 (27.8%) were siblings.
Prevalence of primary open angle glaucoma was 13.7% for offspring and 5.3% for siblings. Conclusion: Prevalence
of primary open angle glaucoma amongst first degree relatives of glaucoma patients is higher than the general
population. Targeted screening of at-risk group will help in early detection and treatment.
Keywords: Opportunistic screening, primary open angle glaucoma, first-degree relative
1. INTRODUCTION
Glaucoma remains the leading cause of irreversible blindness in the world accounting for 8% of all blindness(1).
Currently, over 8.4 million persons are said to be blind from glaucoma with over 60 million with the disease(2). By the
year 2020, it has been predicted that those with glaucoma would climb to 79.6 million and with an estimated 11 million
persons bilaterally blind globally(2). The Nigeria National blindness and Visual Impairment Survey showed that
estimated 1.2 million Nigerians aged ≥40 years have glaucoma(3) and account for 16.7% of all cases of blindness in
Nigeria(4).
Screening for glaucoma is an important tool for reducing the incidence of blindness and visual impairment. Early
detection of the condition in its earlier stage by effective screening will likely result in reduced morbidity and improve
the quality of life(5). Screening of the general population for glaucoma has been found to be cost ineffective because
International Annals of Medicine
Vol1;1(3);2017
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
of the relatively low prevalence of glaucoma in the
general population(6). However, screening in
populations with high prevalence such as the
elderly(7,8), African-American ancestry(9),
Hispanics(10), and those with a family history of
glaucoma(11), have been found to be very useful
because the positive predictive value of available
screening tests is enhanced.
Several epidemiological studies have shown increased
risk of glaucoma in family members of persons with
primary open angle glaucoma. The Baltimore Eye
Survey(12) confirms that family history of Primary
open angle glaucoma (POAG) is an important risk
factor. Similarly, the Barbados Eye Study has
suggested that persons most likely to have POAG are
old men with a history of glaucoma(13). The risk ratio
of developing primary open-angle glaucoma in
persons with positive family history has been
estimated to be 9.2, and increased prevalence of
glaucoma has been found in persons whose first-
degree relatives suffer primary open angle
glaucoma(11,14).
Therefore, examination of family members of those
suffering from primary open-angle glaucoma could be
an effective way of identifying those at higher risk of
having the disease and ensures early detection and
treatment(15).
2. METHODS
Study design and data management
This was prospective population-based study. Primary
open angle glaucoma patients’ first-degree relatives
who accompanied the patients to the Glaucoma clinic
of a tertiary teaching hospital and were not previously
informed, were approached and informed about the
purpose of the study. Those who voluntarily consented
were recruited into the study. The study was carried
between October 2015 and December 2016.
The screening took place on every Tuesday of the
week which is the Glaucoma clinic day. All
participants were offered the screening free of cost.
All consecutive consenting individuals after recording
their demographic data were asked about the
awareness of the family history of glaucoma and
previous screening for glaucoma. They underwent a
complete ocular examination which included visual
acuity using the Snellen chart and refraction (by
autorefractomer GR-2100, Grand Seiko, Japan), slit-
lamp biomicroscopy (Keeler Symphony-40H, UK) of
the anterior segment, applanation tonometry,
gonioscopy and dilated fundus examination with the
+90D indirect lens. Individuals with definitive
glaucoma based on typical glaucomatous optic nerve
damage, ocular hypertension and suspicious appearing
optic nerve heads (≥0.5) were subjected to visual field
testing by Standard threshold automated static
perimetry (SE500 Sonomed Escalon, New York)
using 24-2 pattern. Relatives of glaucoma patients
with other types of glaucomas were excluded from the
screening. Also excluded were participants with
narrow angles on gonioscopy.
Detailed slit-lamp examination of the external ocular
surface, cornea, iris, lens and anterior vitreous was
carried out, and any abnormality noted. The anterior
chamber was inspected and pupillary reaction
carefully observed. Intraocular pressure was measured
in sitting position using handheld applanation
tonometer (HS Clement Clarke International). Three
measurements were carried out for each, and the
average was recorded. Gonioscopy was performed for
each eye using Goldmann three-mirror goniolens, and
the anterior chamber angle was graded using Shaffer’s
classification.
Detailed slit-lamp fundus biomicroscopy with +90D
Volk indirect lens was performed, and the vertical
cup/disc ratio, neuroretinal rim sloping, notching of
optic nerve head, nerve fiber hemorrhages and retinal
nerve fiber layer defects were noted.
The diagnosis of primary open angle glaucoma was
confirmed based on the following criteria(5):
1. Open-angle documented on gonioscopy
2. An optic nerve head cup/disc ratio >0.6 with
typical features of notching of neuroretinal rim,
excavation, thinning or sloping of the neuroretinal
rim in the superior or inferior sector of the optic
nerve head in at least one eye.
3. Visual field defects matching of the nerve head
changes in the visual field with pattern standard
deviation abnormal at 5% level or less; with a
cluster of at least three abnormal points in the
nasal, paracentral or arcuate region of the visual
field with at least one point at <1%. Borderline or
abnormal glaucoma hemifield test on automated
perimetry alone without matching disc changes
was not considered abnormal.
Individuals with large cup/disc ratio with rim slope
with no evidence of characteristic neural rim notch or
thinning, the average intraocular pressure of
<21mmHg on two repeated visits with no evidence of
visual field defects characteristic of glaucoma were
termed glaucoma suspect. Those with average
International Annals of Medicine
Vol1;1(3);2017
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
intraocular pressure ≥21mmHg on two repeated visits
without characteristic optic disc changes or visual field
defects typical of glaucoma were considered as ocular
hypertension. For purposes of this study, Juvenile
onset Open Angle Glaucoma, a subset of Primary
Open Angle Glaucoma seen in ages 5-40 years and
adult onset Primary Open Angle Glaucoma seen in
those above 40 years are taken together.
Those found with proven glaucoma were registered in
the Glaucoma unit of the hospital for treatment and
follow-up. The glaucoma suspects were encouraged to
register for follow-up.
Data obtained were analyzed using the Statistical
Package for Social Sciences (SPSS) version 20 (2014).
Simple statistics such as frequencies and percentages
were determined, and comparisons of associated
variables were made using p–values, Chi-square, and
odd ratio.
Ethical consideration
The study was carried out in compliance with the
tenets of the Helsinki declaration of 1975, as reversed
in 2000. Approval to carry out this study was sought
for and obtained from the Ethical Committee of the
University of Port Harcourt Teaching Hospital.
Informed verbal consent was also obtained from all the
respondents
3. RESULTS
A total of 95 individuals who were first-degree
relatives of 41 patients with Primary open angle
glaucoma receiving treatment at the Glaucoma clinic
of a Tertiary Teaching Hospital, were examined. Fifty-
seven of them (60%) were males, and 38 (40%) were
females. They consisted of 83 (87.37%) offspring and
12 (12.63%) siblings. The mean age was 37.71 ± 8.15
years with age range of 14-56 years, confidence
interval (CI) (30-42.5) (Table 1).
Eighteen first-degree relatives (18.9%) were observed
to have definite Primary open angle glaucoma based
on optic disc nerve head, visual field and open anterior
angle criteria. Seven (38.9%) of those found with
glaucoma were previously diagnosed and are already
on treatment. Another 16 (16.8%) of the relatives were
found to be Glaucoma suspect. Twelve (66.7%) of
those with glaucoma were males while 6 (33.3%) were
females giving a ratio of 2:1. Thirteen (72.2%) of them
were offspring while 5 (27.8%) were siblings. Primary
open angle glaucoma was found in 13.7% of offspring
and 5.3% of siblings of the relatives of the patients
examined. (Table 2).
Twenty (21%) of these relatives were aware that
glaucoma runs in the family, but 7 (33.3%) of them
went for screening because they observed diminution
of vision in at least one eye.
Table 1: Demographic data of respondents
Variable
Frequency (n)
Percentage (%)
Age
10-19
4
2.21
20-29
13
13.68
30-39
43
45.26
40-49
30
31.58
50-59
5
5.26
Sex
Male
57
60
Female
38
40
Marital status
Married
64
67.37
Single
30
31.58
Engaged
1
1.05
Educational status
Primary
7
7.37
Secondary
17
17.89
Tertiary
71
74.74
Relation to patient
Offspring
83
87.37
Sibling
12
12.63
previously diagnosed with glaucoma
Yes
7
7.37
No
88
92.63
4. DISCUSSION
The Nigeria Blindness Survey has shown that most of
the over 1.2 million adults with glaucoma are not
aware that they have the disease(3,4). It is critical to note
that symptoms occur late in Primary open angle
glaucoma (POAG). If the diagnosis is based only on
symptoms, advanced irreversible vision loss is likely.
Patients with POAG need to be identified early
through adequate screening(5,16).
In Nigeria, many studies(17,18,19) have indicated that
patients with glaucoma present late to the hospital.
Therefore, ceasing every opportunity to screen those
at higher risk will help in identifying those with the
disease early and treat them accordingly. Screening of
family members of glaucoma patients is usually done
by inviting such prospective individuals to the
clinic(5,14). Logistical challenges on our part and the
socio-economic status of most of these persons would
International Annals of Medicine
Vol1;1(3);2017
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
make the adoption of that method ineffective.
Rajendrababu et al.(5) got only 7% response rate of
those they invited for screening in India. They had an
issue with logistics. Therefore, we saw a great
opportunity amongst those who accompanied their
glaucoma patient relatives to the Glaucoma clinic to
carry out this study.
Table 2: Demographic data of those found with
glaucoma and glaucoma suspect
Variable
Total
No.
Glaucoma
Glaucoma
suspect
Age
10-19
4
0(0)
0(0)
20-29
13
0(0)
0(0)
30-39
43
5(27.8%)
5(31.25%)
40-49
30
13(72.2%)
9(56.25%)
50-59
5
0(0)
2(12.5%)
Total
95
18(100%)
16(100%)
X2 p-value
7.11(0.01)*
6.94(0.03)*
Gender
Male
57
12(66.7%)
7(43.75%)
Female
38
6(33.3%)
9(56.25%)
Total
95
18(100%)
16(100%)
X2 p-value
4(0.05)*
0.5(0.479)
Marital status
Married
64
18(100%)
15(93.75%)
Single
30
0(0)
1(6.25%)
Engaged
1
0(0)
0(0)
X2 p-value
36(0.001)*
24.5(0.001)*
Educational status
Primary
7
5(27.8%)
1(6.25%)
Secondary
17
5(27.8%)
2(12.5%)
Tertiary
71
8(44.4%)
13(81.25%)
X2 p-value
1.5(0.472)
24.94(0.001)*
Relationship with patient
Offspring
83
13(72.2%)
16(100%)
Sibling
12
5(27.8%)
0(0)
Total
95
18(100%)
16(100%)
X2 p-value
7.11(0.01)*
36(0.001)*
OR(p-value) 95%CI
3.85(0.05)* 1.15-6.13
*p-value statistically significant
The identified prevalence of 18.9% of primary open
angle glaucoma amongst the first-degree relatives of
patients with primary open-angle glaucoma found in
this study is similar to that reported by Vegini et al.(20)
(16.8%). The Vegini’s study also screened those who
accompanied their glaucoma patients to a referral
tertiary health facility. It is lower than that found in a
study in the United States(14) (30.2%) with similar
sample size with our study. It is, however, higher than
13.3% that was found in another study in India(5).
In our study, the prevalence of glaucoma was higher
amongst offspring (13.7%) compare to siblings (5.2%)
as also reported by Vegini et al.(20). However, both the
American and Indian studies(5,14) reported higher
prevalence amongst siblings than offspring. Wolfs et
al.(11) reported a prevalence of 10.4% amongst siblings
of patients and only 1.1% of offspring of patients.
Most of the persons in our study were offspring
(87.4%) while the rest were siblings (12.6%). In our
locality, offspring are more likely to accompany their
parents to the clinic than their siblings. In the Indian
study, more siblings (52%) attended the screening
compare to offspring (33%) and parents (15%). The
family history of glaucoma in a sibling is the greatest
risk factor, followed by glaucoma in a parent(9). The
Baltimore Eye Survey(9) found that the relative risk of
having glaucoma is increased 3.7-fold for individual
who have a sibling with primary open-angle glaucoma
compared to an individual who has a parent with
primary open angle glaucoma that has a 2.2-fold risk
of developing glaucoma. It is obvious from our study
like the other studies(5,14,20) that the prevalence of
primary open-angle glaucoma is higher amongst first
degree relatives than the general populations(2,4,7,8,10).
Therefore, every effort should be directed at getting
this high-risk population screened for the disease.
This study also showed that 21% of those examined
have knowledge of the family history of glaucoma.
Out of the 21% of those who knew the family history
of glaucoma, only about a third (33.3%) of them had
gone for eye screening. Smith and colleagues(22)
reported in their study that 53% of first degree
relatives understood the family history of glaucoma,
but 40% of them were previously screened. However,
Eke et al.(23) reported that nearly all 70 first-degree
relatives they questioned had knowledge of the family
history of glaucoma. In that study, 81% of those aware
of family history of Glaucoma reported that they had
gone for screening for the disease. In Nigeria, poor
knowledge of glaucoma has been identified as a major
factor associated with late presentation of glaucoma
patients(18,19). A robust population-based study in
Nigeria showed that the prevalence of glaucoma was
5.02% with 86% of it being the open angle(4). Our
study clearly shows a higher prevalence of glaucoma
amongst these first-degree relatives compares to the
general population. Therefore, every effort must be
improved to enlighten this the at-risk population like
International Annals of Medicine
Vol1;1(3);2017
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
first degree relatives of glaucoma patients and promote
uptake of glaucoma screening amongst them.
We did not measure the corneal thickness due non-
availability of pachymeter in the clinic. This has
impacted on the true values of the intraocular pressure
recorded by the applanation tonometer we used.
5. CONCLUSION
This study has shown a higher prevalence of open-
angle glaucoma amongst first-degree relatives of
patients with primary open glaucoma compared to the
general population. Focusing on this at-risk group will
help in the early detection of glaucoma in our
environment and help in reducing glaucoma-related
blindness.
6. RECOMMENDATION
To improve case detection of Glaucoma and reduce
visual loss, first-degree relatives of Primary Open
Angle Glaucoma patients should be targeted for
screening
ACKNOWLEDGEMENT
We acknowledge the support of the department of Ophthalmology,
University of Port Harcourt Teaching Hospital for making its visual
field machine available at no cost to the respondents.
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Vol1;1(3);2017
To Cite This Article: Godswill Inye Nathaniel , Elizabeth Akon Awoyesuku. Opportunistic Screening for Glaucoma Amongst Glaucoma Patients’
First Degree Relatives who Accompanied them to Glaucoma Clinic. International Annals of Medicine. 2017;1(4).
https://doi.org/10.24087/IAM.2017.1.4.82
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