Retinal Photoreceptor Outer Segment Length Before and After Light Stimulation - a Pilot Study

Study Overview
=================
Brief Summary
-----------------
It has been shown that reactions of human retinal photoreceptors to a light stimulus can be measured with custom-made, research prototype optical coherence tomography (OCT) systems. This can be used as a biomarker for the function of the photoreceptors. Due to the high technical demands on the system, however, the technique is currently not available for clinical purposes. In this pilot study a protocol to measure changes in retinal photoreceptor layer thickness before and after light stimulation shall be developed based on a commercial OCT system and newly developed algorithms. Other variables, such as circadian processes shall be investigated as well. After measurements in healthy volunteers, the protocol is planned to be applied in patients with primary open angle glaucoma (POAG) and age-related macular degeneration (AMD) to test for feasibility of the method in these patient groups.

Official Title
-----------------
Assessment of Retinal Photoreceptor Outer Segment Length With Optical Coherence Tomography Before and After Light Stimulation - a Pilot Study

Conditions
-----------------
Macular Degeneration, Dry, Primary Open-angle Glaucoma

Intervention / Treatment
-----------------
* Other: White light stimulation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: men and women aged over 18 years signed informed consent form ametropia below 3 diopters ability and willingness to follow instructions for healthy volunteers: normal ophthalmologic findings for primary open angle glaucoma patients (POAG): diagnosed POAG MD <= 10 dB for age-related macular degeneration (AMD): diagnosed dry AMD diagnosed stage II or stage III AMD Exclusion Criteria: Presence of any abnormalities preventing reliable measurements Ocular inflammation and ocular disease interfering with the study aims Use of photosensitizing medication (phototoxic drugs, photoallergic drugs) in the 3 months preceding the study Presence of any condition with the possibility of causing photosensitivity, including systemic lupus erythematosus SLE, Porphyria, Vitiligo, Xeroderma Pigmentosum and Albinism Presence of any form of epilepsy Ocular surgery in the 3 months preceding the study Pregnancy, planned pregnancy or lactating Any medical or surgical history, disorder or disease such as acute or chronic severe organic disease

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: healthy volunteers<br>light stimulation | Other: White light stimulation<br>* Stimulation of the retina with white light<br>|
| Experimental: primary open angle glaucoma patients<br>light stimulation | Other: White light stimulation<br>* Stimulation of the retina with white light<br>|
| Experimental: age-related macular degeneration patients<br>light stimulation | Other: White light stimulation<br>* Stimulation of the retina with white light<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Light stimulation | Optical path length changes between inner segment outer segment junction and retinal pigment epithelium (RPE) will be measured with OCT in 15 healthy volunteers, 10 POAG patients and 10 AMD patients before and after light stimulation | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Light stimulation of contralateral eye | Optical path length changes between inner segment outer segment junction and retinal pigment epithelium (RPE) will be measured with OCT in 15 healthy volunteers, 10 POAG patients and 10 AMD patients before and after light stimulation in the contralateral eye | 1 day | 
| Difference in photoreceptor layer thickness over the course of 8 hours | Influence of circadian rhythm on the length of retinal photoreceptor outer segments | 8 hours | 
| En face maps | test an algorithm for production of en face maps of retinal photoreceptor outer segment length | 1 day | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
light stimulation, retinal photoreceptors, light adaptation, functional optical coherence tomography, optophysiology, intrinsic optical signals