Corneal Biomechanics for Ocular Hypertension, Primary Open-Angle Glaucoma, and Amyloidotic Glaucoma: A Comparative Study by Corvis ST

Figures & data

Table 1 Demographic and Baseline Characteristics of the Study Groups

	Controls (n=53)	POAG (n=61)	AG (n=32)	OHT (n=37)	p-value
Number of patients	28	35	28	24	-
Age (y)	62±10	77±10	53±8	72±8	p<0.001
Male (%)	43%	54%	61%	25%	p=0.008
Right eye (%)	51%	51%	41%	46%	NS
BCVA (logMAR)	0.08±0.14	0.15±0.22	0.12±0.17	0.08±0.12	p=0.036
CCT (µm)	561±35	533±34	538±31	547±28	p<0.001
GAT-IOP (mmHg)	14.02±2.18	13.36±2.97	12.91±2.90	14.14±2.75	NS
GAT-IOPadj (mmHg)	13.57±3.45	14.43±3.51	13.66±3.44	14.35±3.12	NS
bIOP (mmHg)	13.22±2.38	13.00±4.71	13.68±3.53	13.43±2.56	NS
Number of glaucomatous medications	-	2.15±0.93	2.40±1.41	1.84±0.80	NS
Prostaglandin analogues	-	44 (72%)	19 (59%)	22 (59%)	NS
β-blockers	-	48 (79%)	25 (78%)	31 (84%)	NS
CA-inh	-	30 (49%)	20 (63%)	10 (27%)	p=0.010
α agonist	-	12 (20%)	14 (44%)	5 (14%)	p=0.008

Note: Values are presented as means±SD or n (%).

Abbreviations: POAG, primary open-angle glaucoma; AG, amyloidotic glaucoma; OHT, ocular hypertension; y, years-old; BCVA, best-corrected visual acuity; logMAR, logarithm of the minimum angle of resolution; CCT, corneal central thickness; GAT-IOP, intraocular pressure measured by Goldmann applanation tonometry; GAT-IOPadj, intraocular pressure measured by Goldmann applanation tonometry and adjusted for pachymetry; bIOP, biomechanically corrected intraocular pressure; CA-inh, carbonic anhydrase inhibitors; NS, non statically significant; mmHg, millimeters of mercury; µm, micrometers.

Table 2 The Mean Values and Mixed Linear Model (Control Group Set as Reference) for Corvis ST Parameters Adjusted for Age, Gender, GAT-IOP, and Prostaglandin Analogue Medication

	Controls (n=53)	POAG (n=61)	AG (n=32)	OHT (n=37)
A1T (ms)
Mean±SD	7.71±0.29	7.68±0.67	7.67±0.49	7.78±0.37
Coefficient±SE	Reference	0.073±0.164	−0.078±0.153	0.142±0.162
p-value		NS	NS	NS
A1V (m/s)
Mean±SD	0.138±0.019	0.142±0.021	0.142±0.022	0.137±0.024
Coefficient±SE	Reference	−0.001±0.007	0.00005±0.006	−0.007±0.007
p-value		NS	NS	NS
A1DeflL (mm)
Mean±SD	2.29±0.22	2.28±0.16	2.21±0.18	2.28±0.14
Coefficient±SE	Reference	−0.011±0.053	−0.049±0.050	−0.010±.052
p-value		NS	NS	NS
PD (mm)
Mean±SD	4.77±0.31	4.87±0.48	4.85±0.47	4.74±0.32
Coefficient±SE	Reference	0.112±0.138	0.161±0.128	−0.036±0.136
p-value		NS	NS	NS
Radius (mm)
Mean±SD	6.83±1.23	6.56±0.91	6.14±0.62	6.44±0.74
Coefficient±SE	Reference	−0.081±0.260	−0.552±0.247	−0.171±0.253
p-value		NS	0.025	NS
HCDA (mm)
Mean±SD	1.05±0.11	1.05±0.16	1.04±0.21	1.02±0.10
Coefficient±SE	Reference	−0.028±0.050	0.034±0.046	−0.047±0.049
p-value		NS	NS	NS
HCDeflA (mm)
Mean±SD	0.756±0.601	0.887±0.15	0.879±0.192	0.840±0.107
Coefficient±SE	Reference	0.011±0.096	0.213±0.091	−0.012±0.093
p-value		NS	0.019	NS
A2T (ms)
Mean±SD	21.94±0.46	21.87±0.66	22.11±0.67	21.86±0.49
Coefficient±SE	Reference	−0.063±0.196	0.248±0.181	−0.086±0.192
p-value		NS	NS	NS
A2V (m/s)
Mean±SD	−0.23±0.04	−0.26±0.05	−0.25±0.07	−0.25±0.03
Coefficient±SE	Reference	−0.013±0.015	−0.010±0.014	0.001±0.015
p-value		NS	NS	NS
A2DeflL (mm)
Mean±SD	3.31±0.71	3.01±0.74	2.91±0.85	2.96±0.59
Coefficient±SE	Reference	−0.225±0.196	−0.188±0.188	−0.206±0.191
p-value		NS	NS	NS
SSI
Mean±SD	1.244±0.174	1.308±0.232	1.119±0.324	1.322±0.187
Coefficient±SE	Reference	−0.014±0.081	−0.127±0.075	0.031±0.079
p-value		NS	0.090	NS
SPA1
Mean±SD	110.30±22.98	109.03±19.24	108.23±25.90	119.90±19.84
Coefficient±SE	Reference	1.830±7.028	5.687±6.494	12.487±6.890
p-value		NS	NS	0.070
1/R
Mean±SD	8.69±0.78	9.13±1.51	9.66±1.57	8.96±1.14
Coefficient±SE	Reference	−0.137±0.431	0.983±0.399	−0.249±0.424
p-value		NS	0.014	NS
DARatio
Mean±SD	1.62±0.57	1.56±0.05	1.55±0.09	1.55±0.06
Coefficient±SE	Reference	−0.125±0.152	0.225±0.141	−0.169±0.149
p-value		NS	NS	NS

Abbreviations: POAG, primary open-angle glaucoma; AG, amyloidotic glaucoma; OHT, ocular hypertension; SD, standard deviation; SE, standard error; NS, no statistical difference; A1T, time at first applanation; A1V, velocity at first applanation; A1DeflL, Deflection length at first applanation; PD, peak distance; HCDA, deformation amplitude at highest concavity; HCDeflA, deflection amplitude at highest concavity; A2T, time at second applanation; A2V, velocity at second applanation; A2DeflL, deflection length at second applanation; SS1, stress–strain index; SPA1, stiffness parameter at first applanation; 1/R, integrated radius; DARatio, deformation amplitude ration; mm, millimeters; ms, milliseconds; GAT-IOP, Intraocular pressure measured by Goldmann applanation tonometry; PG, prostaglandin analogues.

Table 3 Mixed Linear Model (Primary Open-Angle Glaucoma Group Set as Reference) for Corvis ST Parameters Adjusted for Age, Gender, GAT-IOP, and Prostaglandin Analogue Medication

	Controls (n=53)	POAG (n=61)	AG (n=32)	OHT (n=37)
A1T (ms)
Coefficient±SE	−0.072±0.164	Reference	−0.151±0.164	0.0696±0.113
p-value	NS		NS	NS
A1V (m/s)
Coefficient±SE	0.001±0.007	Reference	0.001±0.007	−0.006±0.005
p-value	NS		NS	NS
A1DeflL (mm)
Coefficient±SE	0.0115±0.054	Reference	−0.037±0.057	−0.037±0.057
p-value	NS		NS	NS
PD (mm)
Coefficient±SE	−0.112±0.138	Reference	0.049±0.138	−0.148±0.097
p-value	NS		NS	NS
Radius (mm)
Coefficient±SE	0.081±0.259	Reference	−0.471±0.282	−0.090±0.205
p-value	NS		*p=0.095	NS
HCDA (mm)
Coefficient±SE	0.028±0.050	Reference	0.062±0.050	−0.019±0.035
p-value	NS		NS	NS
HCDeflA (mm)
Coefficient±SE	−0.011±0.096	Reference	0.202±0.104	−0.023±0.076
p-value	NS		*p=0.052	NS
A2T (ms)
Coefficient±SE	0.063±0.196	Reference	0.311±0.198	−0.023±0.142
p-value	NS		NS	NS
A2V (m/s)
Coefficient±SE	0.013±0.015	Reference	0.003±0.016	0.014±0.012
p-value	NS		NS	NS
A2DeflL (mm)
Coefficient±SE	0.225±0.196	Reference	0.036±0.215	0.019±0.155
p-value	NS		NS	NS
SSI
Coefficient±SE	0.014±0.081	Reference	−0.113±0.082	0.045±0.058
p-value	NS		NS	NS
SPA1
Coefficient±SE	−1.83±7.02	Reference	3.857±7.173	10.657±5.277
p-value	NS		NS	p=0.043
1/R
Coefficient±SE	0.136±0.431	Reference	1.120±0.434	−0.112±0.310
p-value	NS		p=0.010	NS
DARatio
Coefficient±SE	0.125±0.152	Reference	0.350±0.156	−0.044±0.115
p-value	NS		p=0.025	NS

Note: *NS, but a tendency to statistical significance.

Abbreviations: POAG, primary open-angle glaucoma; AG, amyloidotic glaucoma; OHT, ocular hypertension; SD, standard deviation; SE, standard error; NS, no statistical difference; A1T, time at first applanation; A1V, velocity at first applanation; A1DeflL, deflection length at first applanation; PD, peak distance; HCDA, deformation amplitude at highest concavity; HCDeflA, deflection amplitude at highest concavity; A2T, time at second applanation; A2V, velocity at second applanation; A2DeflL, deflection length at second applanation; SS1, stress strain index; SPA1, stiffness parameter at first applanation; 1/R, integrated radius; DARatio, deformation amplitude ration; mm, millimeters; ms, milliseconds; GAT-IOP, Intraocular pressure measured by Goldmann applanation tonometry; PG, prostaglandin analogues.

Table 4 Mixed Linear Model (Amyloidotic Glaucoma Group Set as Reference) for Corvis ST Parameters Adjusted for Age, Gender, GAT-IOP, and Prostaglandin Analogue Medication

	Controls (n=53)	POAG (n=61)	AG (n=32)	OHT (n=37)
A1T (ms)
Coefficient±SE	0.078±0.153	0.151±0.164	Reference	0.220±0.162
p-value	NS	NS		NS
A1V (m/s)
Coefficient±SE	−0.0001±0.006	−0.001±0.007	Reference	−0.007±0.007
p-value	NS	NS		NS
A1DeflL (mm)
Coefficient±SE	0.049±0.050	0.037±0.057	Reference	0.038±0.056
p-value	NS	NS		NS
PD (mm)
Coefficient±SE	−0.161±0.128	−0.049±0.138	Reference	−0.197±0.137
p-value	NS	NS		NS
Radius (mm)
Coefficient±SE	0.551±0.247	0.471±0.282	Reference	0.381±0.277
p-value	p=0.025	*p=0.095		NS
HCDA (mm)
Coefficient±SE	−0.034±0.046	−0.062±0.050	Reference	−0.081±0.049
p-value	NS	NS		*p=0.098
HCDeflA (mm)
Coefficient±SE	−0.213±0.091	−0.202±0.104	Reference	−0.225±0.102
p-value	p=0.019	*p=0.052		p=0.028
A2T (ms)
Coefficient±SE	−0.248±0.181	−0.311±0.198	Reference	−0.334±0.195
p-value	NS	NS		*p=0.087
A2V (m/s)
Coefficient±SE	0.010±0.014	−0.003±0.016	Reference	0.011±0.015
p-value	NS	NS		NS
A2DeflL (mm)
Coefficient±SE	0.188±0.188	−0.036±0.215	Reference	−0.017±0.211
p-value	NS	NS		NS
SSI
Coefficient±SE	0.127±0.075	0.113±0.082	Reference	0.158±0.080
p-value	*p=0.090	NS		p=0.049
SPA1
Coefficient±SE	−5.687±6.493	−3.857±7.173	Reference	6.800±7.066
p-value	NS	NS		NS
1/R
Coefficient±SE	−0.983±0399	−1.120±0.434	Reference	−1.232±0.428
p-value	p=0.014	p=0.010		p=0.004
DARatio
Coefficient±SE	−0.225±0.141	−0.350±0.156	Reference	−0.394±0.153
p-value	NS	p=0.025		p=0.01

Note: *NS, but a tendency to statistical significance.

Abbreviations: POAG, primary open-angle glaucoma; AG, amyloidotic glaucoma; OHT, ocular hypertension; SD, standard deviation; SE, standard error; NS, no statistical difference; A1T, time at first applanation; A1V, velocity at first applanation; A1DeflL, Deflection length at first applanation; PD, peak distance; HCDA, deformation amplitude at highest concavity; HCDeflA, deflection amplitude at highest concavity; A2T, time at second applanation; A2V, velocity at second applanation; A2DeflL, deflection length at second applanation; SS1, stress strain index; SPA1, stiffness parameter at first applanation; 1/R, integrated radius; DARatio, deformation amplitude ration; mm, millimeters; ms, milliseconds; GAT-IOP, Intraocular pressure measured by Goldmann applanation tonometry; PG, prostaglandin analogues.

Figure 1 The mean values of intraocular pressure (IOP) obtained by Goldmann applanation tonometry (GAT-IOP), GAT-IOP corrected for pachymetry (GAT-IOPadj), and biomechanically corrected IOP (bIOP) in study groups: control group, primary open-angle glaucoma (POAG) group, amyloidotic glaucoma (AG) group, and ocular hypertension (OHT) group. *p<0.05.