-- DavidKeating - 20 Oct 2008
2. Identification
3. Protocol use(s)
4. Patient population
5. Technical issues
6. Response evaluation (with example)
Model to calculate recovery time rate.
7. Reporting and storage
Curves and amplitudes x time relationship.
8. Calibration
No specific definition, see ISCEV Standard (2008 update) and Protocols general aspects.
9. Protocol Specifications
10. Relevant References
-- TWikiAdminUser - 11 Feb 2009
Module 15 - recovery after bleaching
The next draft will be compiled by (Messias and Jägle)
1. Scope| For dark-adapted conditions for visual cycle assessment |
| 2.1. Number | 15 |
| 2.2. Version number | 1.0 |
| 2.3. Date of approval |
|
Assessment of rod phototransduction dynamics; |
Vitamin A deficiency;RPE alterations;Visual cycle alterations |
| 4.1. Equipment and facilities | Step sequence must be automatic to ensure precise time intervals. |
| 4.2. Staff expertise and responsibilities | No specific definition, see ISCEV Standard (2008 update) and Protocols general aspects. |
| 4.3. Procedure | Pupil size recording |
| 4.4. Patient Information | Bleaching |
| Description | -1.0 Log cd.s/m² [Pre-bleaching] | 600 cd/m² [Bleaching] | -1.0 Log cd.s/m² [Post-Bleaching] |
| Averages per step | 1 | 1 | 16 |
| Time between averages | 0 | 0 | 60 (s) |
| Adaptation time | 0 | 240 (s) | 0 |
| Acquisition |
|
|
|
| Sample Frequency | 1000 (Hz) | 1000 (Hz) | 1000 (Hz) |
| Sweep pre-trigger time | 20 (ms) | 20 (ms) | 20 (ms) |
| Sweep post-trigger time | 200 (ms) | 200 (ms) | 200 (ms) |
| Sweeps per result | 5 | 1 | 5 |
| Interstimulus interval | 15000 (ms) | 0 (ms) | 15000 (ms) |
| Drift removal | Off | Off | Off |
| Manual rejection of sweeps | Off | Off | Off |
| DC off-set removal | On: 20 (ms) | On: 20 (ms) | On: 20 (ms) |
| Stimulus |
|
|
|
| Pulse frequency |
|
|
|
| Pulse duration (d) | 4 ms |
| 4 ms |
| Stimulus luminance | 0.10 ph cd.s/m² | 0 | 0.10 ph cd.s/m² |
| Stimulus color | White 6500K | White 6500K | White 6500K |
| Background luminance | 0 cd/m2 | 600 ph cd/m2 | 0 cd/m2 |
| Background color | White 6500K | White 6500K | White 6500K |
| Channels (1 and 2) |
|
|
|
| Filter low frequency cutoff | 0.3 (Hz) | 0.3 (Hz) | 0.3 (Hz) |
| Filter high frequency cutoff | 300 (Hz) | 300 (Hz) | 300 (Hz) |
| Y-axis scaling | 50 (uV) | 50 (uV) | 50 (uV) |
Comments on Recovery after bleaching
Back to Recovery after Bleaching I have tried this protocol and have 2 problems with it: 1. The bleach is difficult for healthy subjects to comply with and IMPOSSIBLE for patients with central scotoma's to comply with. Have smaller bleaches been tested? Could Flash bleaches be used? This bleach cannot be used longitudinally, as no patient will consent to have this done to them twice. 2. You cannot average 5 stimuli with an ISI of 15 s each minute since the last flash of t1 must occur at the same time as the first flash of t2. I would suggest only averaging 3 flashes. -Mitch -- MitchellBrigell - 30 Mar 2009Topic revision: r5 - 12 Feb 2009 - 18:57:11 - TWikiAdminUser
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