Night Myopia and Dark Focus of Accommodation

Study Overview
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Brief Summary
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Shifts in accommodation at decreasing luminance levels are considered as principle cause for night myopia. Previous studies with laser optometers quantified the dark focus of accommodation up to 3 D. In addition to the measurement of dark focus, the aim of this study was to investigate the influence of an imaginary target at finite distances on the state of accommodation at scotopic luminance.

Detailed Description
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Accommodation was measured by using an open-field autorefractor (WAM 5500, GRAND SEIKO). Full corrected right eyes of 39 subjects aged from 18 to 40 years were investigated in this randomized, cross-sectional study. Accommodation measurements in photopic luminance were taken for 6 m of empty field and for optotype fixation at 2 m, 1 m and 0.5 m. At scotopic luminance, dark focus of accommodation was examined directly after darkening and after 10 min of dark adaptation. After adaptation, subjects had to visualize imaginary targets in the four distances while accommodation was measured.

Official Title
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Influence of an Imaginary Target on the State of Accommodation Under Scotopic Conditions

Conditions
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Dark Focus of Accommodation

Intervention / Treatment
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* Diagnostic Test: Accommodation Measurement


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age 18 - 44 visual acuity at least 0.8 (5/6) Exclusion Criteria: medication with an impact on the visual system visual disease or disease with an impact on the visual system pregnancy or other hormonal variances drug usage overfatigue at the period of investigation mental handicap

Ages Eligible for Study
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Minimum Age: 22 Years
Maximum Age: 39 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Accommodation in scotopic luminance<br> | Diagnostic Test: Accommodation Measurement<br>* Accommodation was measured for different distances and light conditions.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Shift of accommodation in scotopic luminance (Dark focus) | Accommodative shift in scotopic luminance compared to photopic luminance for empty field (dark focus of accommodation) | Baseline only | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference of accommodation for 2 m target | Accommodative shift in scotopic luminance compared to photopic luminance for the fixation of a target in 2 m | Baseline only | 
| Difference of accommodation for 1 m target | Accommodative shift in scotopic luminance compared to photopic luminance for the fixation of a target in 1 m | Baseline only | 
| Difference of accommodation for 0.5 m target | Accommodative shift in scotopic luminance compared to photopic luminance for the fixation of a target in 0.5 m | Baseline only | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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accommodation, dark focus, night myopia