Lateral inhibition and glaucoma: Solving the structure-function discrepancy.

Lateral inhibition and glaucoma: Solving the structure-function discrepancy. - Lateral inhibition and glaucoma.

Status

Active, not recruiting

Phases

Unknown

Study type

Observational

Source

NL-OMON

Registry ID

NL-OMON37129

Enrollment

Registered

2012-08-02

Start date

2012-08-02

Completion date

Unknown

Last updated

2024-04-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

glaucoma POAG

Interventions

None listed

Eligibility

Age

18 Years to 99 Years

Inclusion criteria

Inclusion criteria: Glaucoma patients aged 18 years or older who visit the ophthalmology outpatient department of the UMCG, provide informed consent form and meet the inclusion-exclusion criteria.;Healthy subjects will consist of people who have signed in, without ophthalmic abnormalities and provide informed consent.

Exclusion criteria

Exclusion criteria: Glaucoma patients: - visual acuity below 0.8 (above 50 years) or below 1.0 (below 50 years of age) - any other eye disease than glaucoma;Healthy subjects: - visual acuity below 0.8 (above 50 years) or below 1.0 (below 50 years of age) - any other eye disease

Design outcomes

Primary

Measure	Time frame
Test 1: Lateral inhibition can be studied in detail with a psycho-physical phenomenon called "illusion of movement." This phenomenon is based on the finding that a thin (dark) line between two (sinusoidal and reverse-phased) alternating in brightness straps on a fixed distance from the line appears to shift (Gregory and Heard The Quarterly J of Exp Psych 1983). With a variant of this experiment, lateral inhibition can be measured (Jansonius and Kuiper 1989). The depth of the lateral bands of the psychophysical line spread function is a measure of lateral inhibition. Test 2. An alternative psycho-physical test to measure lateral inhibition is based on the Westheimer function (Westheimer G. J. Physiol. 1967). To distinguish a stimulus on a background of constant illumination is dependent on the diameter of the background. With a small diameter a reduced sensitivity is found because of spatial summation (the stimulus is less visible). When the diameter increases it fills the receptive field until lateral inhibition starts to work. The sensitivity will increase again to a balance where both spatial summation and lateral inhibition are 'saturated' . Endpoint is the difference in sensitivity between healthy subjects and glaucoma patients measured with a background in diameter where lateral inhibition is expected. Test 3. The final way to measure lateral inhibition is based on contrast sensitivity measurements. Here, we measure a contrast sensitivity function and our outcome measure is the contrast sensitivity at low spatial frequencies relative to the contrast sensitivity at medium spatial frequencies, which is a measure of lateral inhibition.	—

Measure

Time frame

Test 1: Lateral inhibition can be studied in detail with a psycho-physical phenomenon called "illusion of movement." This phenomenon is based on the finding that a thin (dark) line between two (sinusoidal and reverse-phased) alternating in brightness straps on a fixed distance from the line appears to shift (Gregory and Heard The Quarterly J of Exp Psych 1983). With a variant of this experiment, lateral inhibition can be measured (Jansonius and Kuiper 1989). The depth of the lateral bands of the psychophysical line spread function is a measure of lateral inhibition. Test 2. An alternative psycho-physical test to measure lateral inhibition is based on the Westheimer function (Westheimer G. J. Physiol. 1967). To distinguish a stimulus on a background of constant illumination is dependent on the diameter of the background. With a small diameter a reduced sensitivity is found because of spatial summation (the stimulus is less visible). When the diameter increases it fills the receptive field until lateral inhibition starts to work. The sensitivity will increase again to a balance where both spatial summation and lateral inhibition are 'saturated' . Endpoint is the difference in sensitivity between healthy subjects and glaucoma patients measured with a background in diameter where lateral inhibition is expected. Test 3. The final way to measure lateral inhibition is based on contrast sensitivity measurements. Here, we measure a contrast sensitivity function and our outcome measure is the contrast sensitivity at low spatial frequencies relative to the contrast sensitivity at medium spatial frequencies, which is a measure of lateral inhibition.

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Countries

Netherlands

Outcome results