Glaucoma
Conditions
Keywords
Visual Evoked Potentials, Optical Coherence Tomography, Visual Fields
Brief summary
The aim of this study was to evaluate structural and functional improvement after lowering intraocular pressure (IOP) in patients with glaucoma using Spectral Domain Optical Coherence Tomography (SD-OCT), Visual Field (VF) testing, and Visual Evoked Potential (VEP).
Detailed description
Glaucoma exhibits characteristic changes to the optic nerve in the back of the eye. The optic nerve is formed when fibers that overlay the retina come together. This layer is called the retinal nerve fiber layer (RNFL). Optical Coherence Tomography (OCT) is a machine that scans eyes and has the capability of measuring thickness of various layers in the retina and RNFL. This provides important anatomical information. VEP (visual evoked potential) is an imaging system that measures electrical signals from the eye to the brain by using electrodes placed on the forehead and back of head. This is similar in principal to an electrocardiogram of the heart. Visual field testing is done to evaluate the extent of side vision loss caused by various diseases of the eye, including glaucoma. This testing is performed as you stare at a small light directly in front of your eye while lights flash one at a time in every direction on a screen surrounding the central light. You push a button each time you see a flash out of the corner of your eye. Lowering intraocular pressure (IOP) in the eye has been shown to result in reversal of glaucoma changes of the optic nerve in some patients. It has also been suggested that improvement in function (visual field) has been associated with improved optic nerve appearance. This study seeks to provide evidence for reversal of disc appearance and visual function following IOP lowering interventions.
Interventions
DIAGNOSTIC_TESTOptical Coherence Tomography (OCT)
Optical Coherence Tomography (OCT) is a machine that scans eyes and has the capability of measuring thickness of various layers of the retina and nerve fiber layer (NFL).
DIAGNOSTIC_TESTVisual evoked potential (VEP)
Visual Evoked Potential (VEP) is an imaging system that measures electrical activity from the eye to the brain by using electrodes placed on forehead and back of the head similar to electroencephalogram (EEG).
DIAGNOSTIC_TESTHumphrey Visual Field (HVF)
Humphrey Visual Field (HVF) is a test done to evaluate how much peripheral (side) vision has been lost due to glaucoma.
Sponsors
Wills Eye
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 90 Years
Healthy volunteers
No
Inclusion criteria
* All patients with glaucoma (primary open-angle glaucoma, angle recession glaucoma, exfoliation syndrome glaucoma, pigmentary glaucoma and chronic angle closure glaucoma) in whom a pressure-lowering intervention was conducted
Exclusion criteria
* Inability to obtain reliable field or optical coherence tomography pre-intervention * Visual acuity less than 20/40, * Age \<18 or \>90 years, * Other cause for visual field loss not glaucoma, that is, visual field loss due to cataract optic neuropathies, retinal disease * Spherical equivalent refractive error \> +5.00 Diopters and \> 3.00 Diopters cylinder * Concomitant cataract and glaucoma surgery
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Visual Field Mean Deviation | 12 months | Visual field mean deviation as measured in decibels (dB) is the amount of visual field loss compared to age matched controls (people with no eye diseases or visual field loss). Brightness of the flashes of light used to test peripheral vision during a visual field test is measured in decibels. Brighter light has lower number in decibels. The dimmer the light, the higher the number in decibels with a range of 0 to 40 dB. |
| Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | 12 months | Retinal nerve fiber layer (RNFL) thickness in different quadrants of optic nerve and macula are measured pre and postoperatively to evaluate structural changes. |
| Average Cup to Disc Ratio | 12 months | Cup to disc ratio is used to evaluate structural changes comparing the size of the cup to the size of the disc during dilated ophthalmic examination. High eye pressure can cause the cup to enlarge, closer to the size of the disc. This measurement is used to follow progression in glaucoma. A normal range for cup to disc ratio would be 0.0 to 0.4. Advanced glaucoma would be 0.8 to 0.9 cup to disc ratio. |
| Visual Evoked Potential Amplitudes | 12 months | VEP amplitudes at high contrast as measured in microvolts (μV). Electroencephalogram (EEG) measures electrical activity in the brain. VEP measures electrical activity in areas of the brain responsible for vision by using EEG electrodes. The amplitude measurement is the peak of the energy generated (strongest strength of the signal) from the eye's response to the visual stimulus during the VEP. |
| Visual Evoked Potential Latency | 12 months | VEP latency at high contrast as measured in milliseconds (ms). Electroencephalogram (EEG) measures electrical activity in the brain. VEP measures electrical activity in areas of the brain responsible for vision by using EEG electrodes. VEP latencies measure the duration in time of the energy generated (duration of the signal) from the eye's response to a visual stimulus during the VEP. |
| Visual Field | 12 months | Visual field pattern standard deviation in decibels (dB). Visual field results compare visual field loss to age matched controls (people with no eye diseases or visual field loss). Brightness of the flashes of light used to test peripheral vision during a visual field test is measured in decibels. With a localized defect in the visual field, pattern standard deviation (PSD) quantifies amount of loss and progression of glaucoma when in the beginning stages of the disease. |
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Glaucoma Subjects With Intra-ocular Pressure 22-32 mmHg Forty four (44) patients will have testing done using optical coherence tomography (OCT), visual evoked potential (VEP) and visual field (VF).
Testing will be repeated at 1-2 months, 4-6 months and 9-12 months after the initial eye pressure intervention (follow-up testing will be one (1) visual field test, two (2) OCT's and one (1) VEP).
Optical Coherence Tomography (OCT): Optical Coherence Tomography (OCT) is a machine that scans the eyes and has the capability of measuring the thickness of the various layers of the retina and NFL.
Visual Evoked Potential (VEP): Visual Evoked Potential (VEP) is an imaging system that measures the electrical signal from the eye to the brain by using electrodes placed on the forehead and back of the head.
Visual Field: Visual field testing is done to evaluate the extent of side vision loss a patient has with various diseases of the eye, including glaucoma. | 44 |
| Glaucoma Subjects With Intra-ocular Pressure >32 mmHg Six (6) patients will have testing done using optical coherence tomography (OCT), Visual Evoked Potential (VEP) and visual field (VF).
This testing will be repeated one (1) hour, one (1) day and three (3) months following the eye pressure lowering intervention.
Optical Coherence Tomography (OCT): Optical Coherence Tomography (OCT) is a machine that scans the eyes and has the capability of measuring the thickness of the various layers of the retina and NFL.
Visual Evoked Potential (VEP): Visual Evoked Potential (VEP) is an imaging system that measures the electrical signal from the eye to the brain by using electrodes placed on the forehead and back of the head.
Visual Field: Visual field testing is done to evaluate the extent of side vision loss a patient has with various diseases of the eye, including glaucoma. | 6 |
| Control Glaucoma Subjects Eleven (11) patients will have testing done using optical coherence tomography (OCT), Visual Evoked Potential (VEP) and visual field (VF).
Testing will be repeated at 1-2 months, 4-6 months and 9-12 months after the initial testing was completed.
Optical Coherence Tomography (OCT): Optical Coherence Tomography (OCT) is a machine that scans the eyes and has the capability of measuring the thickness of the various layers of the retina and NFL.
Visual Evoked Potential (VEP): Visual Evoked Potential (VEP) is an imaging system that measures the electrical signal from the eye to the brain by using electrodes placed on the forehead and back of the head.
Visual Field: Visual field testing is done to evaluate the extent of side vision loss a patient has with various diseases of the eye, including glaucoma. | 11 |
| Total | 61 |
Baseline characteristics
| Characteristic | Glaucoma Subjects With Intra-ocular Pressure 22-32 mmHg | Glaucoma Subjects With Intra-ocular Pressure >32 mmHg | Control Glaucoma Subjects | Total |
|---|---|---|---|---|
| Age, Continuous | 65.5 years | 65.5 years | 60 years | 64.5 years |
| Sex: Female, Male Female | 19 Participants | 1 Participants | 3 Participants | 23 Participants |
| Sex: Female, Male Male | 25 Participants | 5 Participants | 8 Participants | 38 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 44 | 0 / 6 | 0 / 11 |
| other Total, other adverse events | 0 / 44 | 0 / 6 | 0 / 11 |
| serious Total, serious adverse events | 0 / 44 | 0 / 6 | 0 / 11 |
Outcome results
Primary
Average Cup to Disc Ratio
Cup to disc ratio is used to evaluate structural changes comparing the size of the cup to the size of the disc during dilated ophthalmic examination. High eye pressure can cause the cup to enlarge, closer to the size of the disc. This measurement is used to follow progression in glaucoma. A normal range for cup to disc ratio would be 0.0 to 0.4. Advanced glaucoma would be 0.8 to 0.9 cup to disc ratio.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Average Cup to Disc Ratio | Pre-operative | 0.71 ratio | Standard Deviation 0.12 |
| Glaucoma Subjects With IOP 22-32 mmHg | Average Cup to Disc Ratio | Follow up 1 | 0.69 ratio | Standard Deviation 0.17 |
| Glaucoma Subjects With IOP 22-32 mmHg | Average Cup to Disc Ratio | Follow up 2 | 0.68 ratio | Standard Deviation 0.2 |
| Glaucoma Subjects With IOP 22-32 mmHg | Average Cup to Disc Ratio | Follow up 3 | 0.68 ratio | Standard Deviation 0.08 |
| Glaucoma Subjects With IOP >32 mmHg | Average Cup to Disc Ratio | Follow up 3 | 0.72 ratio | Standard Deviation 0.22 |
| Glaucoma Subjects With IOP >32 mmHg | Average Cup to Disc Ratio | Pre-operative | 0.76 ratio | Standard Deviation 0.17 |
| Glaucoma Subjects With IOP >32 mmHg | Average Cup to Disc Ratio | Follow up 2 | 0.72 ratio | Standard Deviation 0.19 |
| Glaucoma Subjects With IOP >32 mmHg | Average Cup to Disc Ratio | Follow up 1 | 0.74 ratio | Standard Deviation 0.2 |
| Control Glaucoma Subjects | Average Cup to Disc Ratio | Follow up 3 | 0.77 ratio | Standard Deviation 0.01 |
| Control Glaucoma Subjects | Average Cup to Disc Ratio | Follow up 1 | 0.77 ratio | Standard Deviation 0.034 |
| Control Glaucoma Subjects | Average Cup to Disc Ratio | Follow up 2 | 0.75 ratio | Standard Deviation 0 |
| Control Glaucoma Subjects | Average Cup to Disc Ratio | Pre-operative | 0.76 ratio | Standard Deviation 0.09 |
Primary
Retinal Nerve Fiber Layer (RNFL) Thickness Measurement
Retinal nerve fiber layer (RNFL) thickness in different quadrants of optic nerve and macula are measured pre and postoperatively to evaluate structural changes.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 2 | 73.8 um | Standard Deviation 20.53 |
| Glaucoma Subjects With IOP 22-32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 3 | 74.7 um | Standard Deviation 11.03 |
| Glaucoma Subjects With IOP 22-32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Pre-operative | 75.5 um | Standard Deviation 16.1 |
| Glaucoma Subjects With IOP 22-32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 1 | 74.9 um | Standard Deviation 15.22 |
| Glaucoma Subjects With IOP >32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 2 | 75.2 um | Standard Deviation 9.75 |
| Glaucoma Subjects With IOP >32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 1 | 76 um | Standard Deviation 9.08 |
| Glaucoma Subjects With IOP >32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 3 | 74.1 um | Standard Deviation 10.68 |
| Glaucoma Subjects With IOP >32 mmHg | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Pre-operative | 74.3 um | Standard Deviation 10.2 |
| Control Glaucoma Subjects | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 3 | 67.4 um | Standard Deviation 0.5 |
| Control Glaucoma Subjects | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Pre-operative | 70.4 um | Standard Deviation 11.7 |
| Control Glaucoma Subjects | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 1 | 69.4 um | Standard Deviation 2.05 |
| Control Glaucoma Subjects | Retinal Nerve Fiber Layer (RNFL) Thickness Measurement | Follow up 2 | 68.9 um | Standard Deviation 0 |
Primary
Visual Evoked Potential Amplitudes
VEP amplitudes at high contrast as measured in microvolts (μV). Electroencephalogram (EEG) measures electrical activity in the brain. VEP measures electrical activity in areas of the brain responsible for vision by using EEG electrodes. The amplitude measurement is the peak of the energy generated (strongest strength of the signal) from the eye's response to the visual stimulus during the VEP.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Amplitudes | Pre-operative Amplitude High Contrast | 12.7 micro volts (uV) | Standard Deviation 14.4 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Amplitudes | Follow up 1 Amplitude High Contrast | 12.1 micro volts (uV) | Standard Deviation 6.73 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Amplitudes | Follow up 2 Amplitude High Contrast | 12.4 micro volts (uV) | Standard Deviation 3.34 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Amplitudes | Follow up 3 Amplitude High Contrast | 11.8 micro volts (uV) | Standard Deviation 4.3 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Amplitudes | Follow up 3 Amplitude High Contrast | 12.1 micro volts (uV) | Standard Deviation 5.5 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Amplitudes | Pre-operative Amplitude High Contrast | 10.7 micro volts (uV) | Standard Deviation 5.4 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Amplitudes | Follow up 2 Amplitude High Contrast | 9.2 micro volts (uV) | Standard Deviation 4.56 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Amplitudes | Follow up 1 Amplitude High Contrast | 9.5 micro volts (uV) | Standard Deviation 1.78 |
| Control Glaucoma Subjects | Visual Evoked Potential Amplitudes | Follow up 3 Amplitude High Contrast | NA micro volts (uV) | — |
| Control Glaucoma Subjects | Visual Evoked Potential Amplitudes | Follow up 1 Amplitude High Contrast | 12.5 micro volts (uV) | Standard Deviation 8.6 |
| Control Glaucoma Subjects | Visual Evoked Potential Amplitudes | Follow up 2 Amplitude High Contrast | NA micro volts (uV) | — |
| Control Glaucoma Subjects | Visual Evoked Potential Amplitudes | Pre-operative Amplitude High Contrast | 12.1 micro volts (uV) | Standard Deviation 8.33 |
Primary
Visual Evoked Potential Latency
VEP latency at high contrast as measured in milliseconds (ms). Electroencephalogram (EEG) measures electrical activity in the brain. VEP measures electrical activity in areas of the brain responsible for vision by using EEG electrodes. VEP latencies measure the duration in time of the energy generated (duration of the signal) from the eye's response to a visual stimulus during the VEP.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Latency | Pre-operative | 126.1 Milli-seconds (ms) | Standard Deviation 14.67 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Latency | Follow up 1 Latency High Contrast | 110.1 Milli-seconds (ms) | Standard Deviation 18.56 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Latency | Follow up 2 Latency High Contrast | 123.1 Milli-seconds (ms) | Standard Deviation 19.95 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Evoked Potential Latency | Follow up 3 Latency High Contrast | 118.8 Milli-seconds (ms) | Standard Deviation 3.23 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Latency | Follow up 3 Latency High Contrast | 127.5 Milli-seconds (ms) | Standard Deviation 13.76 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Latency | Pre-operative | 117.0 Milli-seconds (ms) | Standard Deviation 20.25 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Latency | Follow up 2 Latency High Contrast | 124.2 Milli-seconds (ms) | Standard Deviation 13.36 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Evoked Potential Latency | Follow up 1 Latency High Contrast | 125.7 Milli-seconds (ms) | Standard Deviation 3.4 |
| Control Glaucoma Subjects | Visual Evoked Potential Latency | Follow up 3 Latency High Contrast | NA Milli-seconds (ms) | — |
| Control Glaucoma Subjects | Visual Evoked Potential Latency | Follow up 1 Latency High Contrast | 139.8 Milli-seconds (ms) | Standard Deviation 1.95 |
| Control Glaucoma Subjects | Visual Evoked Potential Latency | Follow up 2 Latency High Contrast | NA Milli-seconds (ms) | — |
| Control Glaucoma Subjects | Visual Evoked Potential Latency | Pre-operative | 114.1 Milli-seconds (ms) | Standard Deviation 19.7 |
Primary
Visual Field
Visual field pattern standard deviation in decibels (dB). Visual field results compare visual field loss to age matched controls (people with no eye diseases or visual field loss). Brightness of the flashes of light used to test peripheral vision during a visual field test is measured in decibels. With a localized defect in the visual field, pattern standard deviation (PSD) quantifies amount of loss and progression of glaucoma when in the beginning stages of the disease.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field | Follow up 2 | 5.1 dB | Standard Deviation 3.63 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field | Pre-operative | 4.9 dB | Standard Deviation 3.57 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field | Follow up 3 | 5.0 dB | Standard Deviation 4 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field | Follow up 1 | 5.0 dB | Standard Deviation 3.54 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field | Follow up 2 | 5.0 dB | Standard Deviation 2.97 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field | Follow up 1 | 4.0 dB | Standard Deviation 2.95 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field | Pre-operative | 6.3 dB | Standard Deviation 3.33 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field | Follow up 3 | 4.1 dB | Standard Deviation 2.25 |
| Control Glaucoma Subjects | Visual Field | Follow up 1 | 5.8 dB | Standard Deviation 4.42 |
| Control Glaucoma Subjects | Visual Field | Pre-operative | 6.8 dB | Standard Deviation 3.99 |
| Control Glaucoma Subjects | Visual Field | Follow up 3 | 6.4 dB | Standard Deviation 5.04 |
| Control Glaucoma Subjects | Visual Field | Follow up 2 | 6.7 dB | Standard Deviation 4.8 |
Primary
Visual Field Mean Deviation
Visual field mean deviation as measured in decibels (dB) is the amount of visual field loss compared to age matched controls (people with no eye diseases or visual field loss). Brightness of the flashes of light used to test peripheral vision during a visual field test is measured in decibels. Brighter light has lower number in decibels. The dimmer the light, the higher the number in decibels with a range of 0 to 40 dB.
Time frame: 12 months
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field Mean Deviation | Pre-operative | -8.7 dB (decibels) | Standard Deviation 8.2 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field Mean Deviation | Follow up 1 | -8.3 dB (decibels) | Standard Deviation 7.84 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field Mean Deviation | Follow up 2 | -8.5 dB (decibels) | Standard Deviation 7.19 |
| Glaucoma Subjects With IOP 22-32 mmHg | Visual Field Mean Deviation | Follow up 3 | -9.4 dB (decibels) | Standard Deviation 8.5 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field Mean Deviation | Follow up 3 | -14.8 dB (decibels) | Standard Deviation 12.2 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field Mean Deviation | Pre-operative | -13.3 dB (decibels) | Standard Deviation 9.7 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field Mean Deviation | Follow up 2 | -13.8 dB (decibels) | Standard Deviation 10.66 |
| Glaucoma Subjects With IOP >32 mmHg | Visual Field Mean Deviation | Follow up 1 | -14.1 dB (decibels) | Standard Deviation 10.15 |
| Control Glaucoma Subjects | Visual Field Mean Deviation | Follow up 3 | -10.4 dB (decibels) | Standard Deviation 7.4 |
| Control Glaucoma Subjects | Visual Field Mean Deviation | Follow up 1 | -8.6 dB (decibels) | Standard Deviation 7.87 |
| Control Glaucoma Subjects | Visual Field Mean Deviation | Follow up 2 | -9.4 dB (decibels) | Standard Deviation 7.68 |
| Control Glaucoma Subjects | Visual Field Mean Deviation | Pre-operative | -13.2 dB (decibels) | Standard Deviation 10.6 |