Demographics:
Age:
In our study most of the patients age ranged from 51-65 years. The same fact was proved by Kyei and colleagues. They even found glaucoma prevalence among population above 40% in 4 times more among sub-Saharan population than another ethnic group [5].

The pathophysiology of glaucoma explained the increased prevalence of the disease among adults above 50 years. 

Incidence of glaucoma is increased among aging population. Aging is a known risk factor as neurological damage at the cellular level through oxidative stress. Ocular tissues involved in this process are the trabecular meshwork and schlemm’s canal. The disturbance of those structures would decrease the aqueous fluid outflow.

Laboratory studies have shown that retinal ganglia cells and axons are more vulnerable to IOP changes among older population. Structural changes associated with aging will increase the morbidity of the disease [6].

Sex:  
Male gender predilection for glaucoma was noted by studies from South Korea, Ghana and Nigeria. In our study, female noticeably out rated males (62% and 38% respectively).

In our study, females considerably outnumbered males affected with glaucoma. The study by Vajaranant and colleagues revealed that female hormones might be a risk factor for glaucoma as females with early menopause are more susceptible to open angle glaucoma. Also, normal tension glaucoma is more prevalent among females. Previous studies found that women are at higher risk of developing angle closure glaucoma [7].

Intraocular pressure:
IOP is not only the most important risk factor of glaucoma, it is also the main modifiable factor which is targeted by medication and surgical intervention to slow or stop the disease’s progression [8].

In our study, 164 of 332 patients presented with IOP greater than 21. Only ten patients presented with IOP above 50 mm Hg.

Any patient presenting with IOP above 21mmHg is considered glaucomatous if this IOP is associated with the characteristic optic nerve head changes [9].

Glaucoma classification:
Primary open angle glaucoma is the most prevalent classification of glaucoma.

1 in 100 of general population might be affected with open angle glaucoma, POAG is usually asymptomatic in the early stages. On the other hand, angle closure glaucoma presents earlier with on and off visual symptoms and severe pain associated with the acute attacks [10].  

Optic nerve head changes and glaucoma progression:
Optic nerve head cupping and pallor can be found in cases of compressive optic neuropathies, but the structural changes of the optic nerve head seen in glaucoma patients are unique and not usually seen in other etiologies of the optic nerve neuropathies. The variations of the normal optic nerve C/D ratio add to the challenge. Nevertheless, the longitudinal direction of CDR enlargement is found to be characteristic for glaucoma structural changes of the optic nerve head [11].  

In the study by Kokou and colleagues, a vertical increase of CDR f 1.79% occurs annually is the study population, associated with neuro-retinal rim thinning and RNFL thinning of 1.64% and 0.93% respectively [12].

Increased diameter of the nerve cup optic associated with glaucoma indicating the loss in the retinal ganglion cells. The cup-disc ratio (CDR) is a known diameter of the disease progression and the resulting structural damage reflecting glaucoma severity.

Although recently there is a running debate regarding the specificity of CDR as an indicator for glaucoma diagnosis or prognosis, CDR is still a recognized popular glaucoma progression parameter. Therefore, OCT machines manufactured today usually include an in-built software for estimating CDR and comparing it with the saved data of normal population [13].

Glaucoma medical treatment:
Treatment options for glaucoma are chosen based on the classification of glaucoma and the baseline IOP. The most effective anti-glaucoma drugs nowadays are Prostaglandin F2alpha analogues. Topical beta-blockers can reduce the IOP by 20-27%. Carbonic Anhydrase Inhibitors (CAI) are available in both systemic and topical forms. Adrenergic agonists lower IOP by reducing aqueous production. combination therapy showed better efficiency and less side effects than prescribed multiple eye drops. 35% of our participants received two drugs-therapy, the percentage received three drugs. 13% required 4 drugs to control IOP in some point of the course of the disease. Studies proved that beta-blockers when added to a prostaglandine agonist, CAI, Adrenergic agonist or pilocarpine will provide better IOP lowering effect compared to the effect of each drug separately prescribed [14].

Prostaglandin analogue is considered the first line of medical treatment of glaucoma. In our study only 42.1% were using prostaglandin analogue while 79.3% were on CAI.  According to Sarfo and colleagues the choice of medication for glaucoma in Sub-Saharan Africa depends on its price and availability. Sudan was in a state of war in the time of the study, unavailability of certain drugs might limit medication choice [15,16].

Disease severity, associated factors:
The African population showed a severe form of the disease compared with the Caucasians. They have a higher IOP on presentation and a more rapid progression of glaucoma [10,17].

Patients with diabetes: diabetic patients with uncontrolled fasting blood sugar are more susceptible to elevated IOP. Glaucoma is more prevalent among diabetic patients compared to non-diabetic patients. Studies emphasize on oxidative stress and cell apoptosis as common physiopathological processes shared between diabetes and glaucoma. Glial cells dysfunction is also a degenerative process shared by both diabetes and glaucoma which eventually leads to severe form of glaucoma progression among diabetic patients. Additionally, diabetes might cause structural changes of trabecular meshwork leading to elevation of IOP [18,19].

In our study, 74% of glaucomatous patients have a severe form of the disease compared to 59% of the non-diabetic cases.

In the Canary Islands study by Gonzalez-Hernandez and colleagues, 203,115 diabetic patients were followed for 15 years, the study revealed a higher glaucoma incidence over time, increasing with advanced age. They also concluded that vascular diabetic changes would add up to optic nerve structural changes in glaucomatous patients. The researchers concluded that diabetic patients are candidate for glaucoma screening especially with advanced age [20]. Aging process is associated with increased glaucoma severity and structural optic nerve head changes expressed as CDR changes, although in our study the age groups from (31-50 years), (51-65 years) and (>66 years) showed very approximate percentages of glaucoma severity which were: 64%, 67% and 68% respectively. Cases below 30 years showed only moderate CDR progression. These findings support the evidence that glaucoma among Africans progresses before 40 years into the severe form of the disease.

Glaucoma progression relation to the patient’s sex: in this study 73% of the male patients presents with the severe form of the disease compared to 60% of the females. As we discussed above the female patients outnumbered the male patient in our participants but they showed a milder form of the disease [21].

Sex hormone might have a protective role in glaucoma progression, estrogen in pre-menopausal females protects the optic nerve head in glaucoma slowing structural damage of the neural cells. On the other hands, males and post-menopausal females develop more structural damage with the same levels of IOP changes [22].