Measurement of the hypotenuse of the vertical optic nerve head cup with spectral-domain optical coherence tomography for the structural diagnosis of glaucoma

Figures & data

Figure 1 Measurement of the hypotenuse of the vertical optic nerve head cup using the depth (A) and length (B) of the cup as the sides of a right-angled triangle whose hypotenuse is calculated by the Pythagorean theorem.

Table 1 Demographic characteristics of study participants

Demographic characteristics	Group 1: glaucoma MD <−7 dB (n=38)	Group 2: glaucoma MD ≥−7 dB (n=44)	Group 3: healthy subjects (n=13)
Sex, n (%)
Male	13 (34.2)	14 (31.8)	5 (38.5)
Female	25 (65.8)	30 (68.2)	8 (61.5)
Ethnicity, n (%)
African-Brazilians	6 (15.8)	6 (13.63)	0 (0)
White	30 (79.0)	38 (86.6)	12 (92.3)
Mixed	2 (5.2)	0 (0)	1 (7.7)

Abbreviation: MD, mean deviation.

Figure 2 Box plot of average circumpapillary retinal nerve fiber layer (RNFL) thickness.

Notes: Group 1: glaucoma mean deviation <−7 dB (60); Group 2: glaucoma mean deviation ≥−7 dB (74); Group 3: control (22).

Table 2 Global average and median circumpapillary RNFLthickness measured by SD-OCT

Groups (number of eyes)	Global average RNFL ± PD*, μm	Median (IQR), μm
Group 1: glaucoma	62.0±3.3	54.0 (49.0; 75.8)
MD <−7 dB (60)
Group 2: glaucoma	84.4±1.8	85.0 (74.0; 94.0)
MD ≥−7 dB (74)
Group 3: control (22)	96.6±2.3	97.0 (90.5; 102.0)

Note:

* Significantly different between the three groups (P<0.001).

Abbreviations: IQR, interquartile range; MD, mean deviation; PD, pattern deviation; RNFL, retinal nerve fiber layer; SD-OCT, spectral-domain optical coherence tomography.

Table 3 Mean extension and mean depth of the vertical optic nerve head cup and the hypotenuse between these values

Groups (number of eyes)a	Extension (mean ± PD), μm	Depth (mean ± PD), μm	Hypotenuse (mean ± PD), μm
Group 1: glaucoma	1,323.7±322.9	476.7±230.9	1,419.8±347.2
MD <−7 dB (60)
Group 2: glaucoma	1,141.7±260.9	451.3±157.9	1,234.6±258.8
MD ≥−7 dB (74)
Group 3: control (21)	667.3±256.2	225.43±150.8	685.79±315.4

Note:

a Eyes with zero depth of optic nerve head cup (n=1) were excluded from this analysis.

Abbreviations: MD, mean deviation; PD, pattern deviation.

Figure 3 Box plot of the mean hypotenuse of the vertical optic nerve head cup for glaucoma groups and controls in different vertical diameters of the optic disc.

Notes: Group 1: glaucoma mean deviation <−7 dB (60); Group 2: glaucoma mean deviation ≥−7 dB (74); Group 3: control (21).

Table 4 Mean (SE) of the hypotenuse of the vertical optic disc in nerves with vertical diameter <1.5 mm and the significance between groups (n=20)a

Groups (number of eyes)	Group 1: glaucoma MD <−7 dB (8)	Group 2: glaucoma MD ≥−7 dB (8)	Group 3: control (4)
Group 1: glaucoma	–	0.069	<0.001
MD <−7 dB (8): 1,112±91 µm
Group 2: glaucoma	0.069	–	0.014
MD ≥−7 dB (8): 906±68 µm
Group 3: control (4): 393.41±136.04 µm	0.001	0.014	–

Note:

a Significance was calculated using generalized estimating equations.

Abbreviations: MD, mean deviation; SE, standard error.

Table 5 Mean (SE) of the hypotenuse of the vertical optic disc in nerves with vertical diameter between 1.50 and 2.00 mm and the significance between groups (n=120)a

Groups (number of eyes)	Group 1: glaucoma MD <−7 dB (49)	Group 2: glaucoma MD ≥−7 dB (57)	Group 3: control (14)
Group 1: glaucoma	–	<0.001	<0.001
MD <−7 dB (49): 1,449±44 µm
Group 2: glaucoma	<0.001	–	<0.001
MD ≥−7 dB (57): 1,228±34 µm
Group 3: control (14): 739±103 µm	<0.001	<0.001	–

Note:

a Significance was calculated using generalized estimating equations.

Abbreviations: MD, mean deviation; SE, standard error.

Table 6 Mean (SE) of the hypotenuse of the vertical optic disc in nerves with vertical diameter >2.0 mm and the significance between groups (n=16)a

Groups (number of eyes)	Group 1: glaucoma MD <−7 dB (3)	Group 2: glaucoma MD ≥−7 dB (9)	Group 3: control (4)
Group 1: glaucoma	–	<0.001	<0.001
MD <−7 dB (3): 1,989±103 µm
Group 2: glaucoma	<0.001	–	<0.001
MD ≥−7 dB (9): 1,514±60 µm
Group 3: control (4): 857±53 µm	<0.001	<0.001	–

Note:

a Significance was calculated using generalized estimating equations.

Abbreviations: MD, mean deviation; SE, standard error.

Figure 4 Scatter plot of the correlation between the mean deviation (MD) of standard automated perimetry and the hypotenuse of the vertical optic nerve head cup.

Figure 5 Scatter plot of the correlation between peripapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain optical coherence tomography and the hypotenuse of the vertical optic nerve head cup.

Figure 6 Box plot of the percentile groups of the hypotenuse of the vertical optic nerve head cup.

Figure 7 Box plot of the mean deviation (MD) of standard automated perimetry in each percentile group of the hypotenuse of the vertical optic nerve head cup.

Note: *These are single more extreme outliers of the visual field MD values in this percentile.

Figure 8 Box plot of circumpapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain optical coherence tomography in each percentile group of the hypotenuse of the vertical optic nerve head cup.

Table 7 Distribution of eyes with and without glaucoma among the four percentile groups of the HVOC

HVOC percentile group	Group 1: glaucoma MD <−7 dB	Group 2: glaucoma MD ≥−7 dB	Group 3: healthy eyes (control)	Total
1, n (%)	5 (10.2)	14 (24.6)	11 (78.6)*	30 (25)
2, n (%)	5 (10.2)	23 (40.4)	2 (14.3)	30 (25)
3, n (%)	18 (36.7)**	11 (19.3)	1 (7.1)	30 (25)
4, n (%)	21 (42.9)**	9 (15.8)	0 (0)	30 (25)
Total, n (%)	49 (100)	57 (100)	14 (100)	120 (100)

Notes:

* The number of controls in HVOC group 1 was significantly higher than in the other groups (P<0.001).

** The number of glaucomatous eyes with MD <−7 dB in HVOC groups 3 and 4 was significantly higher than in groups 1 and 2 (P<0.001).

Abbreviations: MD, mean deviation; HVOC, hypotenuse of the vertical optic nerve head cup.

Figure 9 Structural and functional findings in a glaucomatous eye in percentile group 1 of the HVOC (mean =940 µm, mean MD =−4.70 (1.2) dB). (A) Circumpapillary RNFLT; (B) standard automated perimetry grayscale map; (C) B-scan of the largest vertical optic disc cup and length and depth used to calculate the HVOC.

Abbreviations: HVOC, hypotenuse of the vertical optic nerve head cup; MD, mean deviation; RNFLT, retinal nerve fiber layer thickness.

Figure 10 Structural and functional findings in a glaucomatous eye in percentile group 2 of the HVOC (mean =1,128 µm, mean MD =−5.10 (1.0) dB). (A) Circumpapillary RNFLT; (B) standard automated perimetry grayscale map; (C) B-scan of the largest vertical optic disc cup and length and depth used to calculate the HVOC.

Abbreviations: HVOC, hypotenuse of the vertical optic nerve head cup; MD, mean deviation; RNFLT, retinal nerve fiber layer thickness.

Figure 11 Structural and functional findings in a glaucomatous eye in percentile group 3 of the HVOC (mean =1,390 µm, mean MD =−10.40 (1.4) dB). (A) Circumpapillary RNFLT; (B) standard automated perimetry grayscale map; (C) B-scan of the largest vertical optic disc cup and length and depth used to calculate the HVOC.

Abbreviations: HVOC, hypotenuse of the vertical optic nerve head cup; MD, mean deviation; RNFLT, retinal nerve fiber layer thickness.

Figure 12 Structural and functional findings in a glaucomatous eye in percentile group 4 of the HVOC (mean =1,662 µm, mean MD =−12.90 (1.4) dB). (A) Circumpapillary RNFLT; (B) standard automated perimetry grayscale map; (C) B-scan of the largest vertical optic disc cup and length and depth used to calculate the HVOC.

Abbreviations: HVOC, hypotenuse of the vertical optic nerve head cup; MD, mean deviation; RNFLT, retinal nerve fiber layer thickness.