Comparison of localised nerve fibre layer defects in normal tension glaucoma and primary open angle glaucoma

Abstract

Aim: To compare the pattern of localised nerve fibre layer (NFL) defects in normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). Methods: 50 NTG eyes and 36 POAG eyes, all with localised NFL defects, were enrolled. On retinal NFL photography, the proximity of the defect to the centre of the fovea (angle α) and the sum of the angular width of the defects (angle β) were determined. Angle α was the angle made by a line from the centre of the fovea to the disc centre and a line from the disc centre to the disc margin, where the nearest border of the defect met. The patterns of localised NFL defects in NTG and POAG were compared with angles α and β. Independent t test was used for statistical analysis. Results: Angle α in NTG (35.1 (SD 20.0)°) was significantly smaller than that of POAG (45.9 (21.9)°) (p=0.02), while angle β in NTG (49.0 (31.9)°) was significantly larger than that of POAG (33.1 (23.9)°) (p=0.01). Conclusions: The pattern of NFL defects in NTG was different from that in POAG. Localised NFL defects in NTG were closer to the fovea and wider in width than those in POAG.

Retinal Nerve Fiber Loss in High‐ and Normal‐Tension Glaucoma by Optical Coherence Tomography

“…However, previous studies that proposed a different pattern of glaucomatous damage in NTG and HTG were based on the findings that the patients with HTG tended to have diffuse defects [1][2][3][4] and patients with NTG tended to have focal damage. 1,[5][6][7][8] Because eyes with HTG and NTG showed a mixture of a localized and diffuse damage in our study, this finding supports the theory that there is a similar RNFL defect pattern between eyes with HTG and NTG. It should be noted that even for OCT RNFL parameters, such as inferotemporal and superotemporal thickness values, which have been shown to be very precise in differentiating healthy eyes from those with early glaucoma, 12 they were not significantly different between HTG and NTG groups.…”

Retinal Nerve Fiber Loss in High‐ and Normal‐Tension Glaucoma by Optical Coherence Tomography

“…However, previous studies that proposed a different pattern of glaucomatous damage in NTG and HTG were based on the findings that the patients with HTG tended to have diffuse defects [1][2][3][4] and patients with NTG tended to have focal damage. 1,[5][6][7][8] Because eyes with HTG and NTG showed a mixture of a localized and diffuse damage in our study, this finding supports the theory that there is a similar RNFL defect pattern between eyes with HTG and NTG. It should be noted that even for OCT RNFL parameters, such as inferotemporal and superotemporal thickness values, which have been shown to be very precise in differentiating healthy eyes from those with early glaucoma, 12 they were not significantly different between HTG and NTG groups.…”

Wedge Defects on Optical Coherence Tomography Angiography of the Peripapillary Retina in Glaucoma: Prevalence and Associated Clinical Factors

“…Densiometry profiles of DHs have suggested an arterial origin, 63 which may further support the notion of vascular insufficiency as opposed to pressure-induced damage. Given that studies have also reported an association between NTG and wedge-shaped RNFL thinning, 19,[64][65][66][67] this theory posits another explanation for the association and spatial correlation between DH and wedge defects seen in this study, in which both may have a common vascular etiology. Nevertheless, it is worth noting that nonpathologic DH have been reported in nonglaucomatous eyes as well, though at a much lower rate.…”

Angular Location of Retinal Nerve Fiber Layer Defect: Association With Myopia and Open-Angle Glaucoma

“…Unfortunately, one of the above-noted studies did not evaluate the patients’ myopic degree. 11 In our study, the angular location of the RNFL defect did not differ between NTG and HTG, both measured from the disc and BMO center. However, remarkably, the difference in angle measured from the center of the disc and BMO was greater in NTG than in HTG.…”

Retinal Nerve Fiber Loss in High‐ and Normal‐Tension Glaucoma by Optical Coherence Tomography

“…However, previous studies that proposed a different pattern of glaucomatous damage in NTG and HTG were based on the findings that the patients with HTG tended to have diffuse defects [1][2][3][4] and patients with NTG tended to have focal damage. 1,[5][6][7][8] Because eyes with HTG and NTG showed a mixture of a localized and diffuse damage in our study, this finding supports the theory that there is a similar RNFL defect pattern between eyes with HTG and NTG. It should be noted that even for OCT RNFL parameters, such as inferotemporal and superotemporal thickness values, which have been shown to be very precise in differentiating healthy eyes from those with early glaucoma, 12 they were not significantly different between HTG and NTG groups.…”

Wedge Defects on Optical Coherence Tomography Angiography of the Peripapillary Retina in Glaucoma: Prevalence and Associated Clinical Factors

“…Densiometry profiles of DHs have suggested an arterial origin, 63 which may further support the notion of vascular insufficiency as opposed to pressure-induced damage. Given that studies have also reported an association between NTG and wedge-shaped RNFL thinning, 19,[64][65][66][67] this theory posits another explanation for the association and spatial correlation between DH and wedge defects seen in this study, in which both may have a common vascular etiology. Nevertheless, it is worth noting that nonpathologic DH have been reported in nonglaucomatous eyes as well, though at a much lower rate.…”

Angular Location of Retinal Nerve Fiber Layer Defect: Association With Myopia and Open-Angle Glaucoma

“…Unfortunately, one of the above-noted studies did not evaluate the patients’ myopic degree. 11 In our study, the angular location of the RNFL defect did not differ between NTG and HTG, both measured from the disc and BMO center. However, remarkably, the difference in angle measured from the center of the disc and BMO was greater in NTG than in HTG.…”

Retinal Nerve Fiber Loss in High‐ and Normal‐Tension Glaucoma by Optical Coherence Tomography

“…However, previous studies that proposed a different pattern of glaucomatous damage in NTG and HTG were based on the findings that the patients with HTG tended to have diffuse defects [1][2][3][4] and patients with NTG tended to have focal damage. 1,[5][6][7][8] Because eyes with HTG and NTG showed a mixture of a localized and diffuse damage in our study, this finding supports the theory that there is a similar RNFL defect pattern between eyes with HTG and NTG. It should be noted that even for OCT RNFL parameters, such as inferotemporal and superotemporal thickness values, which have been shown to be very precise in differentiating healthy eyes from those with early glaucoma, 12 they were not significantly different between HTG and NTG groups.…”

Wedge Defects on Optical Coherence Tomography Angiography of the Peripapillary Retina in Glaucoma: Prevalence and Associated Clinical Factors

“…Densiometry profiles of DHs have suggested an arterial origin, 63 which may further support the notion of vascular insufficiency as opposed to pressure-induced damage. Given that studies have also reported an association between NTG and wedge-shaped RNFL thinning, 19,[64][65][66][67] this theory posits another explanation for the association and spatial correlation between DH and wedge defects seen in this study, in which both may have a common vascular etiology. Nevertheless, it is worth noting that nonpathologic DH have been reported in nonglaucomatous eyes as well, though at a much lower rate.…”

Angular Location of Retinal Nerve Fiber Layer Defect: Association With Myopia and Open-Angle Glaucoma

“…Unfortunately, one of the above-noted studies did not evaluate the patients’ myopic degree. 11 In our study, the angular location of the RNFL defect did not differ between NTG and HTG, both measured from the disc and BMO center. However, remarkably, the difference in angle measured from the center of the disc and BMO was greater in NTG than in HTG.…”