Pattern of presentation and visual outcome of glaucoma in a tertiary hospital, Makurdi, Nigeria
KN Malu1, AV Ramyil2, DD Malu3
1 Department of Surgery, College of Medicine and Health Sciences, Bingham University Teaching Hospital, Jos, Nigeria
2 Department of Ophthalmology, College of Health Sciences Jos University Teaching Hospital, Jos, Nigeria
3 Department of Family Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
Date of Submission 29-Oct-2020
Date of Decision 28-Dec-2020
Date of Acceptance 22-Jan-2021
K N Malu
Department of Surgery, College of Medicine and Health Sciences, Bingham University Teaching Hospital, Jos
DOI: 10.4103/jomt.jomt_58_20
Background: About 15% of blindness in Africa is due to glaucoma. The Nigerian National Blindness and Visual Impairment Survey found that glaucoma accounted for 16.7% of blindness with regional variations. The purpose of the study was to find the regional pattern of presentation and visual outcome to implement preventive measures. Methods: This was a descriptive retrospective study of new patients who presented to the eye clinic of Benue State University Teaching Hospital, Makurdi and were diagnosed of glaucoma. Results: In this study, 795 consecutive new patients who fulfilled the diagnostic criteria for glaucoma were included. Their mean age was 45.5 ± 18.3. There were 450 (56.6%) males. More patients presented in the fourth and fifth decade of life (n = 299, 37.6%). Primary open-angle glaucoma (inclusive of juvenile open-angle glaucoma, n =595, 74.8%, and normal tension glaucoma, n = 8, 1.0%) accounted for a total of 603 (75.8%). There were 145 (18.2%) glaucoma suspects, 23 (2.9%) primary angle-closure glaucoma, 20 (2.5%) secondary glaucoma, and four cases of congenital glaucoma. Vertical cup-to-disc ratio of ≥0.9 was in 634 (39.9%) of eyes; 274 (34.4%) were bilateral, and were all considered to have severe, advanced or end-stage glaucoma. About 203 (25.5%) had discs asymmetry of ≥0.2. About 355 (22.3%) patients' eyes were blind: 95 (11.9%) bilateral and 165 (20.8%) uniocular. Conclusion: Open-angle glaucoma was most common, and patients presented at a young age with severe eye disease, visual impairment, and blindness.
Keywords: Glaucoma, pattern, presentation, visual outcome
Malu K N, Ramyil A V, Malu D D. Pattern of presentation and visual outcome of glaucoma in a tertiary hospital, Makurdi, Nigeria. J Med Trop 2021;23:23-8
Malu K N, Ramyil A V, Malu D D. Pattern of presentation and visual outcome of glaucoma in a tertiary hospital, Makurdi, Nigeria. J Med Trop [serial online] 2021 [cited 2022 Jan 20];23:23-8. Available from: https://www.jmedtropics.org/text.asp?2021/23/1/23/314859
Glaucoma is an optic neuropathy that presents with a characteristic optic disc damage and visual field defect with intraocular pressure as one of the modifiable risk factors, leading to irreversible blindness. It is the second most common cause of blindness worldwide, in Africa,[1],[2] and in Nigeria.[3] It was estimated that by 2020, about 79.6 million people worldwide would have glaucoma and 74% attributable to open angle type.[2]
About 8.4 million people are blind from glaucoma worldwide and 15% of blindness in Africa is due to glaucoma.[4],[5],[6],[7]
Significantly, many studies have revealed glaucoma is more prevalent in Africans, specifically in sub-Saharan Africans and people of African ancestry. Prevalence in Africans is four times higher than in Caucasians.[8],[9] The most prevalent of the glaucoma is primary open-angle glaucoma (POAG).[8],[9],[10]
In Ghana eye survey of Tema region, POAG was seen in 6.8% of those above 40 years and 14.6% of those who were 80 years and order.[11]
Glaucoma in Africans tends to present at an earlier age; about one or two decades earlier than among Caucasians.[8],[9],[10],[11],[12]
It also runs a more aggressive course with higher intraocular pressures and severe visual damage.[8],[9],[10],[11],[12]
The global initiative "VISION 2020: The Right to Sight" (V2020) aimed to reduce the prevalence of blindness to <0.5% in all countries or to <1% in any community.[1]
In Africans, studies have shown that about 90% of sufferers are unaware of their disease, leading to late presentation.[11],[12] About 50% of patients may present blind in one or both eyes.
Glaucoma awareness has been exceptionally low in African populations because of other competing diseases, such as cataract, river blindness, trachoma, childhood malnutrition, malaria, and a host of other diseases that receive the attention of sponsoring Governments and Nongovernmental Organizations (NGOs).
Community-based studies show the impact of glaucoma on visual impairment and blindness in Nigeria. In Ibadan, the south-west zone of Nigeria, Agbeja-Baiyeroju et al.[13] found glaucoma was implicated in 11.1% of blindness and 2.7% of 1794 workers had glaucoma. In Benin 24.4% of 154 new patients coming to the eye clinic were found to be blind from glaucoma.[14]
In the Nigerian National Blindness and Visual Impairment Survey glaucoma accounted for 16.7% of blindness.[15]
Elsewhere in other West African countries, in Akwapim South district of Ghana, glaucoma was the cause of blindness in 7.7% of those older than 30 years and 8.5% of those aged 40 years and older.[9] In the Cameroun, a 10-year review of 1343 blind hospital patients found 8% blindness resulted from glaucoma.[16]
Benue State University Teaching Hospital (BSUTH) is a tertiary institution in the southern part of Middle Belt and it provides care to patients in Benue, Nasarawa, Taraba, and Kogi States, and their environs. It has facilities and eye care personnel that caters to patients with eye disease, including glaucoma.
Knowing the patterns of presentation and the visual outcomes for patients with glaucoma will help stakeholders in planning, organizing, educating to increase awareness of the disease, and developing management strategies for the people of the state and its environs. This in turn will help reduce visual impairment from glaucoma and blindness.
This was a descriptive, retrospective, hospital-based study of new patients who presented to the eye clinic of BSUTH, Makurdi, the State capital of Benue State of Nigeria, and were diagnosed with glaucoma between July, 2013 and December 2017 (41 months).
The study was approved by the Human Research and Ethics Committee of BSUTH.
Patients' personal and sociodemographic data were redacted from the records which included name, age, gender, ethnicity, and occupation. The patient's history, recorded visual acuity at presentation and best corrected for each eye, full ocular examination and investigations and diagnosis were collected from the records.
The visual impairment record followed the definition proposed by the World Health Organization (WHO) with the addition of mild visual impairment in those with presenting visual acuity of <6/12–6/18.[17]
Direct ophthalmoscopy was used to evaluate the optic nerve head and retina.
Intraocular pressure measurement was done using Goldmann applanation tonometer mounted on the slit lamp biomicroscope. The anterior chamber angles assessment was done using Goldmann three mirror gonio lens.
The Schaffer grading system was used for grading the anterior chamber angles. Special note was taken of the visibility of the pigmented trabecular meshwork, color, presence of synechiae, new blood vessels, pigmentation, and exfoliative materials. Schaffer grade 0, I, and II were considered as close angles while III and IV were considered as open angles. An intraocular pressure measurement ≥21 mmHg was deemed abnormal.[18]
The subjects also had central visual field tested with Optopol PTS 910 (Zawierci, ul Zabia, Poland); automated perimetry and digital fundus imaging with Canon CR-2 Plus AF Camera (OHTA-KU Tokyo Japan).
All the patients with open angles had their pupils dilated for stereoscopic examination of the vitreous, optic nerve head and retina with a 78-diopter lens and fundus photo. The subjects with narrow angles had their fundus imaging without pupillary dilatation.
The vertical cup-to-disc ratio (VCDR) measurement took the cup, superiorly from 11 to 1 o'clock, the inferior aspect, from between 5 and 7 o'clock positions.
Subjects with characteristic optic nerve head cupping of VCDR of ≥0.7 or VCDR asymmetry of ≥0.2 between the two eyes, rim loss, focal notching, optic nerve head saucerization, corresponding visual field loss, with or without raised Intraocular Pressures (IOP) were diagnosed as having glaucoma.[19]
A diagnosis of POAG was based on the age of the patient at diagnosis (≥16 years), with open angle on gonioscopy and the IOP of >21 mmHg, presence of glaucomatous optic neuropathy in the eye, retinal nerve fiber defect, and visual field defects consistent with glaucoma.[19]
The diagnosis of normal tension glaucoma (NTG) was made in those with the above characteristics but with IOP ≤ 21 mmHg.
Patients with characteristics of POAG who were <16 years were diagnosed with juvenile open-angle glaucoma (JOAG). Those who were <5 years but with evidence of buphthalmos or breaks in Descemet membrane were diagnosed with true congenital glaucoma.[19]
The diagnosis of primary angle-closure glaucoma (PACG) was based on the presence of angle-closure from gonioscopy in more than two quadrants (Schaffer grade 0, 1, II), with characteristic glaucomatous optic neuropathy and corresponding visual field defects. It was classified as acute PACG if there were features of acute elevated IOP, pain, and cornea edema.[19]
Secondary glaucoma was based on the evidence of any ocular or systemic abnormalities giving rise to glaucoma as in ocular trauma, hypermature cataract, uveitis or couching, neovascularization, pigment dispersion, or exfoliative materials in anterior chamber angles. Where lens opacification precluded fundus view the IOP of ≥30 mmHg and, the presence of an afferent pupillary defect with visual acuity of hand movement or worse made the diagnosis.[19]
Subjects were deemed glaucoma suspects if they had IOP ≥ 21 mmHg with suspicious optic disc, or VCDR asymmetry of >0.2, but no obvious visual field defects.[19]
The data was entered into Microsoft excel sheet, and statistical analyses done with SPSS version 20 (SPSS, Inc, Chicago, IL, USA). Simple frequencies, mean or cross-tabulations were used to present the data. The chi-square test was used to compare variables and a P-value <0.05 was considered statistically significant.
In this study, 795 consecutive new patients that fulfilled the diagnostic criteria for glaucoma were included. The mean age of the participants was 45 ± 18.3 and ranged from 6 weeks to 98 years. There were more males 450 (56.6%). In this study, 299 (37.6%) were in the fourth and fifth decade of life. The prevalence in subjects >40 years was 473 (59.6%).
POAG including JOAG (n = 595, 74.8%) and NTG, n = 8 (1.0%) occurred in a total of 603 patients (75.8%) shown in [Table 1]. Also, 145 patients (18.2%) were classified as glaucoma suspects. There were 23 (2.9%) patients with PACG. Twenty (2.5%) patients had secondary glaucoma; 12 due to trauma, three from possible complications of couching, two from rubeosis and uveitis each, while one was steroid induced. Four cases of congenital glaucoma were recorded.
Table 1: Sociodemography of 795 patients and glaucoma subtypes
The mean VCDR for the right eye was 0.80 ± 0.16 and 0.85 ± 0.13 for the left eye. Also 321 (40.5%) subjects were deemed as having severe, advanced or end stage glaucoma with VCDR of ≥0.9 which was noted in 313 (39.4%) right eyes, 634 (39.9%) left eyes, and bilaterally in 274 (34.4%). This number went up to 484 (60.8%) patients when patients with moderate glaucoma (VCDR of >0.7–0.85) were included [Table 2].
Table 2: Glaucoma severity according to vertical cup-to-disc ratio and the presenting visual acuity of the 795 glaucoma patients
Ninety-five (11.9%) patients presented blind in both eyes whereas 165 (20.8%) were blind in one eye by visual acuity test. In total, 355 (22.3%) of the eyes were blind at presentation. Also, 296 (37.2%) presented with bilateral visual impairment and 158 (19.9%) with uniocular visual impairment.
Refractive errors were the most common associated findings 118 (14.8%), followed by cataracts.
This study reports ocular presentations and visual outcome of new patients presenting to the eye clinic with glaucoma at the BSUTH, Makurdi, Nigeria. POAG (including JOAG and NTG) was the most common subtype in these patients with glaucoma. This finding is similar to those in other hospital-based studies in Nigeria.[20],[21],[22]
Most subjects presented below the age of 60.
This is not surprising since studies have found people of African ancestry present about a decade or two earlier than the corresponding age among the Caucasians.[1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12]
There were more males evaluated and diagnosed with glaucoma. Most studies do not show a significant gender difference.[12],[20] This male dominance may reflect their pattern of access to medical care compared to females.
The presence of POAG in three quarters of patients is high. This is similar to findings by Olawoye and Tarella[20] who reported 70.8% in Ibadan. POAG presents with gradual painless destruction of sight. By the time the sufferer is aware of the disease because of visual impairment, the loss is already extensive and irreversible.
Glaucoma suspects formed a large proportion of glaucoma subtypes seen. The designation of glaucoma suspect was significantly high among those in their second and third decades of life, which may indicate that these individuals may eventually develop glaucoma, highlighting the importance of close follow-up and early screening for glaucoma in this population.
PACG accounted for only few cases diagnosed in this study group. Although it is not a common form of glaucoma among Nigerians and West Africans, our findings are much less than a study in Ibadan where a prevalence of 8.3% of PACG was reported[20] but higher than 1.7% of Benin city study.[21] A much higher prevalence 18.5%was found in an Ethiopian study.[23] PACG does exist among glaucoma sufferers and should be looked for and treated.
Secondary glaucoma accounted for a small fragment of glaucoma diagnosis. They were as result of trauma, complications from couching, rubeosis, uveitis, and use of steroid medication. This represent similar findings with most studies in the region where trauma and complications from traditional couching for cataract is still rampant despite good visual outcomes from present day cataract surgery with intraocular lens implant.[5],[24]
Four cases of congenital glaucoma were recorded. Most of them did not present early and presented with buphthalmos and already opacified corneas where vision could not be saved.
One in three of the subjects presented with a VCDR of ≥0.9 in both eyes and majority of the eyes were deemed to have severe, advanced or end-stage glaucoma by optic nerve head morphology.
Moderate to end-stage glaucoma (VCDR of >0.7) was seen in more than half of our patients. This is similar to the study in Kano where Bowman and Kirupananthan[25] found 63% of the eyes had VCDR of >0.8 at presentation and a higher value of 70% in Dar es-Salaam hospital audit of glaucoma patients.[26]
At presentation to the clinic, about one-fifth of eyes tested blind by visual acuity criteria, with bilateral visual impairment seen in one-third of our patients. Bowman and Kirupananthan[25] reported a higher rate in a Kano hospital where 53% of eyes presented blind. Mafwiri et al.[26] in Dar es-Salaam indicated that 29% of glaucoma patients presented blind. This supports the notion that patients with glaucoma in African societies present extremely late in the course of disease when vision is irreversibly damaged. With poor rehabilitative measures available in society, patients resort to begging, with additional collateral damage as the young children leading or caring for patients cannot go to school.
Glaucoma is an age-related disease, and as expected, cataracts were the commonest ocular comorbid condition in those who had POAG.
Refractive errors were also frequent comorbidity in glaucoma patients.
Patients with glaucoma tend to present with visual dissatisfaction even at an early stage of the disease, and that may lead to their frequent presentation for new lens prescriptions.[27],[28] This may present an important opportunity to screen them for glaucoma.
Treating comorbid cataracts in patients with glaucoma can yield dissatisfaction as post-operative visual outcomes can be disappointing especially if initially only the cataract had been identified by a less experienced practitioner or if the patient was not counseled appropriately.
The strength of this study is that it has provided firsthand information concerning glaucoma that has not been available before in Benue State.
The limitations of the study include its location at a university affiliated hospital, making it less representative of the larger population as most participants were staff and students.
Lack of more sophisticated instruments for glaucoma assessment and follow-up such as Humphrey field analyzer, which is the gold standard for visual field assessment was another challenge.
The lack of a pachymeter for corneal thickness, and ocular coherent tomography for retinal nerve fiber layer assessment machines also limited evaluation of patients.
In conclusion, we present a study of new glaucoma patients seen at a tertiary institution in Makurdi Benue State. The prevalence of glaucoma was high in this center with open-angle glaucoma being the most common subtype. Most presented at a younger age, with more severe eye disease and resultant visual impairment or blindness.
The findings in this study should help the stakeholders in planning, organizing, educating, and raising awareness of the disease, and developing management strategies for the people of Benue State and its environs that will help reduce visual impairment and blindness from glaucoma.
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Malu K N
Ramyil A V
Malu D D
visual outcome