Comparison of moderate and advanced glaucoma patients in Ghana

To compare moderate and advanced glaucoma patients in Ghana.

A retrospective cross-sectional study of 164 patients with primary open-angle glaucoma (POAG) were separated into moderate and advanced glaucoma groups. Definitions of moderate and advanced POAG were derived from International Geographical and Epidemiologic Ophthalmology criteria and included clinical assessment of optic disc atrophy and Humphrey automated perimetry. Data were collected at the patient’s first visit prior to initiation of therapy. Eligible POAG patients included those ≥30 years old with reliable Humphrey visual field (HVF) results, no past POAG diagnosis, treatment, or evidence of a secondary cause for glaucoma. Main outcome measures included comparisons of intraocular pressure (IOP), cup-to-disk ratio (CDR), best corrected visual acuity (VA), age, Humphrey mean deviation (MD), and pattern standard deviation (PSD).

Of 164 charts reviewed, 90 (54.9%) advanced and 74 (45.1%) moderate POAG patients were compared. Mean age was 59.36 versus 55.53 years, respectively. Significant differences in IOP, CDR, CDR asymmetry, and HVF results were described. IOP > 30 mmHg was associated with CDR > 0.7 and MD greater than −12 dB in both eyes.

Significant differences were found between IOP, CDR, MD and PSD values. HVF is predictive of pretreated IOP, CDR, and severity of POAG and it is strongly encouraged as part of the standard glaucoma work up in all Ghanaian patients.

Keywords: glaucoma, intraocular pressure, Ghana
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Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness worldwide.1 The number of persons affected is estimated to be in the region of 66.8 million with 6.7 million blind.2 This disorder is characterized by progressive optic neuropathy eventually leading to loss of central vision and total blindness in its final stages. A population study in Ghana reported that POAG affects 7.7% and 8.5% of people 30 and 40 years of age, respectively3 whereas 1.9% of Americans over 40 years of age are reported affected.4

Established risk factors for POAG in Ghanaian patients include elevated intraocular pressure (IOP), a family history, old age, and African ancestry.3 Recent studies in Ghana have also identified late presentation and a delay in diagnosis as significant risk factors.5,6 Treatment consists of lowering the IOP through medical or surgical methods. 7 As of 2004, there are 45 ophthalmologists practicing in Ghana, or approximately one per 500,000 persons.8 The majority of these physicians practice in the outpatient setting near the capital city of Accra. Patients in this practice setting are the focus of this manuscript.

This study aims to describe and compare two POAG patient groups at separate stages of disease severity for associations between clinical findings including IOP, cup-to-disk ratio (CDR), CDR asymmetry, age, visual acuity (VA) and Humphrey visual field (HVF) mean deviation (MD), and pattern standard deviation (PSD).

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This was a retrospective cross-sectional study involving 164 patient charts reviewed at the Emmanuel Eye Clinic, a large outpatient eye clinic in Accra, Ghana with an annual volume that exceeds 30,000 patients. Data were gathered from the patients’ initial visits prior to initiation of medical therapy.

Inclusion criteria
Two broad patient groups were formed and defined according to modified International Geographical and Epidemiologic Ophthalmology (ISGEO) POAG criteria (Table 1).9 The first group was defined as having moderate glaucoma, with clinical findings showing disk cupping (CDR 0.7–0.8) without a visual field defect (VFD) or a CDR < 0.7 with a confirmed VFD. The second group was defined as having advanced glaucoma, with clinical findings showing either advanced structural and functional damage (CDR > 0.7 with a confirmed VFD) or advanced optic nerve atrophy (CDR > 0.9) with or without satisfactory HVF results. Eligible patients included those ≥30 years old with a diagnosis of POAG on record, no past diagnosis or treatment for glaucoma or ocular hypertension elsewhere and no history or clinical evidence for a secondary or congenital cause of glaucoma.

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