Ignite Creation Date:
2024-05-05 @ 4:51 PM
Last Modification Date:
2024-10-26 @ 9:25 AM
Study NCT ID:
NCT00328835
Status:
COMPLETED
Last Update Posted:
2006-10-17
First Post:
2006-05-18
Brief Title:
Optic Nerve Compliance Study
Sponsor:
Capital Vision Research Trust
Organization:
Capital Vision Research Trust
Study Overview
Official Title:
Optic Nerve Compliance Study
Status:
COMPLETED
Status Verified Date:
2006-05
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
Chronic glaucoma is one of the leading causes of blindness and visual loss in the developed world It is a condition where long term exposure to high eye pressures intra-ocular pressure damages the nerve fibres in the eye This damage can be seen by examiners as changes in the optic nerve The exact mechanism of how the high intra-ocular pressure causes nerve damage is unknown Both physiological and mechanical mechanisms are thought to play a role Previous authors have reported structural changes in the connective tissue of optic nerves of eyes with glaucoma Structural changes in the optic nerve head which affect the mechanical compliance of the nerve may be significant in the cause of glaucomatous nerve damage This study aims to assess the compliance of the optic disc in subjects with and without glaucoma We would test compliance by imaging the optic discs of participants before and during a brief less than two minutes increase in intra-ocular pressure We would aim to repeat the tests on the same subjects 3 years later to see how compliance changed We would also seek to correlate other important parameters such as corneal thickness and visual field changes with our findings
Detailed Description:
Chronic glaucoma is one of the leading causes of blindness and visual loss in the developed world the following reference gives rate of visual impairmentblindness caused by glaucoma in one cross-section of an older Australian population as 6 - Foran S Wang JJ Mitchell P Causes of visual impairment in two older population cross-sections the Blue Mountains Eye Study Ophthalmic Epidemiol 2003 Oct104215-25 Glaucoma is a condition where long term exposure to high eye pressures intra-ocular pressure damages the nerve fibres in the eye The exact mechanism of how the high intra-ocular pressure causes nerve damage is unknown Albon J Purslow PP Karwatowski WS Easty DL Age related compliance of the lamina cribrosa in human eyes Br J Ophthalmol 2000 Mar843318-23 Both physiological and mechanical mechanisms are thought to play a role Previous authors have reported structural changes in the connective tissue of optic discs of eyes with glaucoma and postulated that this may contribute to changes in the compliance of the optic nerve head Pena JD Netland PA Vidal I Dorr DA Rasky A Hernandez MR Elastosis of the lamina cribrosa in glaucomatous optic neuropathy Exp Eye Res 1998 Nov675517-24 Structural changes in the optic nerve head which affect the mechanical compliance of the nerve may be significant in the cause of glaucomatous nerve damage This study aims to assess the compliance of the optic disc in subjects with and without glaucoma We would test compliance by imaging the optic discs of participants before and during a brief increase in intra-ocular pressure We would aim to repeat the tests on the same subjects 3 years later to see how the optic nerve compliance changed We would also look to correlate changes with other ocular parameters such as corneal thickness and visual field defects
1 Non-glaucoma group
Inclusion criteria
Age over 18
Exclusion criteria
Previous eye surgery Best corrected visual acuity 69 Chronic eye disease including glaucoma Glaucomatous optic disc Ocular perfusion abnormalities eg previous retinal artery or vein occlusion or abnormal vasculature including those whose retinal circulation might be compromised by pressure on the eye
2 Glaucoma group
Inclusion criteria
Age over 18 Diagnosis of glaucoma visual field proven Stable well controlled glaucoma
Exclusion criteria
Secondary glaucoma eg uveitis neovascular glaucoma etc Advanced or fixation-threatening visual field changes Previous eye surgery Chronic eye disease not including glaucoma Ocular perfusion abnormalities eg previous retinal artery or vein occlusion or abnormal vasculature including those whose retinal circulation might be compromised by pressure on the eye
Two different groups of participants will be studied those with glaucoma and those without glaucoma Participants will have a routine eye examination performed by an experienced doctor Information such as visual acuity intra-ocular pressure corneal thickness and optic nerve appearance will be obtained Then participants will have their optic nerves imaged by a Heidelberg retinal tomograph HRT The intra-ocular pressure will then be artificially raised to approximately 50 mmHg for approximately two to four minutes using a suction cup oculopressor The optic nerve will be imaged again by the HRT during that time From the HRT images we will calculate the optic nerve compliance using measures such as mean position of the disc and optic cup area and volume This data will then be analysed statistically to look for a significant difference in the optic nerve compliance of the two groups Participants will then undergo the same testing procedure 3 years later to see how their optic nerve compliance has changed We will then examine these changes to see how they correlate with changes in their vision These changes would include development of glaucoma decreased visual acuity reduced visual field
Clinical methods - history and examination Visual field testing in those with glaucoma using an automated visual field testing machine
Intra-ocular pressure measurement using a Goldmann tonometer Corneal thickness measurement using a Pachmate pachymeter Optic disc images using a Heidelberg retinal tomograph a confocal scanning diode laser ophthalmoscope
There is a theoretical risk that a short term rise in intra-ocular can compromise the blood supply to the optic nerve and cause optic nerve damage However a previous study looking at optic nerve compliance found no side-effects after a short term rise in intraocular pressure induced with a suction cup Augusto A Harris A Cantor L Abreu M Weinland M Effects of short term increase of intraocular pressure on optic disc cupping British Journal of Ophthalmology 1998 82 880-883 Also a recent study has shown that a short term rise in intra-ocular pressure does not alter the response of retinal and optic nerve head blood flow Garhofer G Resch H Weigert Lung S Simader C Schmetterer L Short-term increase of intraocular pressure does not alter the response of retinal and optic nerve head blood flow to flicker stimulation Investigative Ophthalmology Visual Science 2005 465 880-883 We also know from clinical experience that patients with short term rises in intra-ocular pressure caused by vitreo-retinal surgery and acute angle closure glaucoma do not have long term side effects from raised pressure for hours
To further reduce the risk of side-effects we will exclude those with advanced or fixation threatening glaucoma changes We will also exclude those whose retinal circulation is seen to be compromised by digital pressure on the eye during examination
1 Non-glaucoma group
Inclusion criteria
Age over 18
Exclusion criteria
Previous eye surgery Best corrected visual acuity 69 Chronic eye disease including glaucoma Glaucomatous optic disc Ocular perfusion abnormalities eg previous retinal artery or vein occlusion or abnormal vasculature including those whose retinal circulation might be compromised by pressure on the eye
2 Glaucoma group
Inclusion criteria
Age over 18 Diagnosis of glaucoma visual field proven Stable well controlled glaucoma
Exclusion criteria
Secondary glaucoma eg uveitis neovascular glaucoma etc Advanced or fixation-threatening visual field changes Previous eye surgery Chronic eye disease not including glaucoma Ocular perfusion abnormalities eg previous retinal artery or vein occlusion or abnormal vasculature including those whose retinal circulation might be compromised by pressure on the eye
Two different groups of participants will be studied those with glaucoma and those without glaucoma Participants will have a routine eye examination performed by an experienced doctor Information such as visual acuity intra-ocular pressure corneal thickness and optic nerve appearance will be obtained Then participants will have their optic nerves imaged by a Heidelberg retinal tomograph HRT The intra-ocular pressure will then be artificially raised to approximately 50 mmHg for approximately two to four minutes using a suction cup oculopressor The optic nerve will be imaged again by the HRT during that time From the HRT images we will calculate the optic nerve compliance using measures such as mean position of the disc and optic cup area and volume This data will then be analysed statistically to look for a significant difference in the optic nerve compliance of the two groups Participants will then undergo the same testing procedure 3 years later to see how their optic nerve compliance has changed We will then examine these changes to see how they correlate with changes in their vision These changes would include development of glaucoma decreased visual acuity reduced visual field
Clinical methods - history and examination Visual field testing in those with glaucoma using an automated visual field testing machine
Intra-ocular pressure measurement using a Goldmann tonometer Corneal thickness measurement using a Pachmate pachymeter Optic disc images using a Heidelberg retinal tomograph a confocal scanning diode laser ophthalmoscope
There is a theoretical risk that a short term rise in intra-ocular can compromise the blood supply to the optic nerve and cause optic nerve damage However a previous study looking at optic nerve compliance found no side-effects after a short term rise in intraocular pressure induced with a suction cup Augusto A Harris A Cantor L Abreu M Weinland M Effects of short term increase of intraocular pressure on optic disc cupping British Journal of Ophthalmology 1998 82 880-883 Also a recent study has shown that a short term rise in intra-ocular pressure does not alter the response of retinal and optic nerve head blood flow Garhofer G Resch H Weigert Lung S Simader C Schmetterer L Short-term increase of intraocular pressure does not alter the response of retinal and optic nerve head blood flow to flicker stimulation Investigative Ophthalmology Visual Science 2005 465 880-883 We also know from clinical experience that patients with short term rises in intra-ocular pressure caused by vitreo-retinal surgery and acute angle closure glaucoma do not have long term side effects from raised pressure for hours
To further reduce the risk of side-effects we will exclude those with advanced or fixation threatening glaucoma changes We will also exclude those whose retinal circulation is seen to be compromised by digital pressure on the eye during examination
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None