A comparative study of intraocular pressure in myopia and hyperopia among a Nigerian population just diagnosed with primary open angle glaucoma in Benin City

Abstract

Background: Increasing evidence suggests that high myopia is salient in the pathologic process of POAG, and IOP (Primary Open Angle Glaucoma (POAG), and Intra-ocular Pressure (IOP)) remains the crucial risk factor for this condition. Still, some other studies have signified that glaucoma was diagnosed in myopes independent of IOP, suggesting that predisposition to glaucoma in myopes may not be dependent on mechanisms related to high pressures.The aim of this study was therefore to compare the intraocular pressure in myopes and hyperopes in a Nigerian population just diagnosed with POAG to ascertain if proclivity to glaucoma in myopes is mainly dependent on IOP. Methods: This research was conducted as a retrospective study in the Optometry/Ophthalmology Department at Stella Obasanjo Women and Children Hospital, Benin City, Nigeria. The sample consisted of cases seen between 2011 and 2013. A total of 166 eyes with glaucoma and refractive errors (80 (48.19%) with myopia, and 86 (51.81%) with hyperopia) with an age range of 10 to 85 years, were used for this study. Results: Newly diagnosed glaucomatous myopes had a significantly higher mean IOP than recently diagnosed hyperopes (unpaired t-test, p= 0.004). Also, a significant inverse correlation was obtained between refractive errors and intraocular pressure (Pearson correlation, r = -.245, p = 0.001) i.e. as refractive errors progressed deeply into more minus (myopic) regions, IOP increased. Conclusions: The relationship between glaucoma and myopia is pressure mediated. The ascending levels of intraocular pressure that occurred with increasing extents of myopia demonstrate that POAG evolves too soon in participants with high myopia than in hyperopia and accentuates the seriousness of glaucoma surveillance in the myopic population.

Relationship between Refractive Error and Intraocular Pressure in Children Attending the University of Port-Harcourt Teaching Hospital Eye Clinic

“…This implies that as myopia increases, the intraocular pressure also increases. This is consistent with findings by Osaiyuwu et al [11] and Megwas et al [22] Tham et al [24] in Singapore, Sowjanya et al [25] in India and Jin et al [26] in Korea also obtained similar findings. However, Chinawa et al reported no correlation between myopia and intraocular pressure [27].…”

“…An association between refractive error and intraocular pressure has been reported among children and adults [9,10]. Increasing levels of intraocular pressure has been found in individuals with myopia as opposed to those with emmetropia or hypermetropia [4,11]. Myopic eyes have been shown to have higher intraocular pressures than non-myopic eyes and it has been hypothesised that a higher intraocular pressure may affect the development of myopia in children [9].…”

“…Myopia is a recognised risk factor for primary open angle glaucoma and intraocular pressure is the only modifiable risk factor associated with glaucoma [4]. The ascending levels of intraocular pressure seen with increasing degree of myopia demonstrate that Primary Open Angle Glaucoma occurs earlier in individuals with high myopia than in hyperopia and accentuates the seriousness of glaucoma surveillance in the myopic population [11].…”

Comparison of Ocular Biomery in Primary Open Angle Glaucoma and Non-Glaucoma in South West Nigeria

“…This observation was also supported by Osaiyuwu et al . [ 52 ] Theories surrounding the interaction between increasing degrees of myopia and intraocular pressure have been inconclusive. It was suggested that increasing levels of intraocular pressure results in gradual stretching of the eyeball leading to myopia[ 53 ] while others suggested that increase in scleral tension within the lamina cribosa results in increased susceptibility to damage in myopes even when the intraocular pressure is normal.…”

Determining Association of Myopia and Primary Open Angle Glaucoma

“…highly consistent with the present study. Osaiyuwu et al, 24 analyzed the Nigerian population and demonstrated that myopes had higher mean IOP compared to hypermetropic. They added that the myopes had more incidence of POAG that was associated with IOP in a Nigerian population.…”