Intraocular PressureNCT03299400
Continuous Intraocular Pressure Patterns in Spine Surgery
A study testing Contact lens sensor in people with Intraocular Pressure, run by The University of Hong Kong at 1 site in Hong Kong.
Trial summary
Post-operative visual loss is a rare but serious complication after surgery. It is most significantly correlated with prone spinal surgery with a prolonged duration. The cause and risk factors are not elucidated, but the majority of the cases are due posterior ischaemic optic neuropathy (PION). Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Intraocular Pressure
- What is being tested?
- Contact lens sensor
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 10 participants
- Where
- 1 siteHong Kong
- Study dates
- 9 May 2016to 9 May 2017
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Signed informed consent
- Age 18 to 80 years inclusive
- No pre-existing eye pathology (excluding refractive error), patients with glaucoma, history of eye injury or ophthalmic surgery
- No known allergy to contact lens material
- Patients undergoing anterior cervical spine surgery and prone spine surgery for duration of 3 hours or longer
Who cannot join
- Unable to comply with follow up or give informed consent
- Cannot tolerate wearing contact lens
- Has active eye infection
Trial locations and contacts
1 site in 1 country.
About this study
Post-operative visual loss is a rare but serious complication after surgery. It is most significantly correlated with prone spinal surgery with a prolonged duration. The cause and risk factors are not elucidated, but the majority of the cases are due posterior ischaemic optic neuropathy (PION). This entity is directly related to the ocular perfusion pressure (OPP), which is estimated as the difference between mean arterial blood pressure (MAP) and intraocular pressure (IOP). Autoregulation is believed to maintain a constant perfusion to the optic nerve despite fluctuations in the perfusion pressure.
IOP is known to increase in the prone position thus putting susceptible patients at risk for inadequate ocular nerve perfusion. Most of the evidence comes from animal and healthy volunteer studies and cannot give an accurate insight into the subtle changes of intra-operative IOP. All the published studies employed the use of a tonometer, which may have rooms for measurement errors due to inadvertent pressure on the globe while retracting the eyelids, particularly when there is significant periorbital/conjunctival swelling in the prone position. The majority of the studies recruited healthy volunteers in a simulated surgical setting so other fluctuating parameters, which can affect intraoperative IOP, cannot be measured. In the few reports where patients undergoing surgery in the prone position were studies, IOP measurements were taken at non-continuous monitoring at time intervals, thus the effects of changes in blood volume, MAP, central venous pressure (CVP) and PaCO 2 could not be studied. Lastly, all the literature consists of case series only with no control group so the effect of position cannot be evaluated independently of the other factors.
The investigators therefore propose to conduct a prospective study with continuous intraoperative IOP monitoring to give us further insight into the physiological changes of IOP in patients undergoing spine surgery, and identify the risk factors related to fluctuations of IOP during prone spinal surgery.
Read the detailed description
Post-operative visual loss (POVL) is a rare but serious complication after surgery.
One of the known associations is prone spinal surgery with a prolonged duration.
The cause is not completely understood, but some of the risk factors for developing POVL include anaemia, hypotension, the duration of surgery and patient factors such as age, hypertension and atherosclerosis. There are also some unidentifiablerisk factors that may predispose young healthy patients to POVL. Once the patient develops POVL, it is usually irreversible, and the patient is left with a permanent disability.
The majority of POVL cases that occur with prone spinal surgery are due to posterior ischaemic optic neuropathy (PION). PION is directly related to the ocular perfusion pressure (OPP), which is estimated as the difference between mean arterial blood pressure (MAP) and intraocular pressure (IOP). Autoregulation is believed to maintain a constant perfusion to the optic nerve despite fluctuations in the perfusion pressure.
However, there is a knowledge gap in the physiological changes of IOP during prone surgery. IOP is a highly dynamic parameter, and the most widely used method to measure it is using a handheld tonometer. The main limitation of this technique is the isolated nature of its measurements, as it can only be taken at regular intervals, and may not reflect the full range of IOP changes. Studies on IOP during prone position in the current literature have all used this technique. 1-5 Hence subtle changes of IOP can be undetected, as interval measurements cannot reflect short-term variations that occur within seconds or minutes. Furthermore, most of the studies are performed on animals or healthy volunteers 5,6 , which further limit the interpretation of their results. For the few studies performed on anaesthetised patients undergoing spinal surgeries, the duration of surgery is short or mixed, so the critical time point may not have been studied. The American Society of Anesthesiologists Postoperative Visual Loss Registry suggests that an anaesthetic duration of greater than 6 hours is more correlated with POVL.
Using state of the art technology Over the past five years, advances in technology have led to the development of devices that allow 24 hour continuous IOP monitoring. The new system makes use of microelectromechanical systems, nanotechnology, and telemetry to allow continuous monitoring. A disposable contact lens sensor, first proposed by Leonardi et al. 8 , is now commercially available (SENSIMED Triggerfish; Sensimed AG, Lausanne, Switzerland). This technology can acquire data points over a 24 hour period corresponding to 30 seconds of continuous measurements. It measures changes in the ocular dimensions at the corneoscleral junction, which corresponds to changes to IOP and volume. The microprocessor within the lens transmits data to an external antenna, and the profiles can be stored in a portable recorder. 9 Although this sensor does not measure IOP directly, it gives measurements with a composite of IOP and volume changes, and it is most valuable in documenting relative changes of IOP-related events and their timing. It is also well tolerated in real life patients, and have been used to document IOP changes in patients with glaucoma and thyroid eye disease. 9-11 This is the only non-invasive temporary continuous monitoring in the system that can be used in human beings. This new technology is therefore ideal in detecting subtle changes in IOP pattern in prone spinal surgery. It will provide a continuous monitoring which can be correlated with the patient's level of anaesthesia, arterial pressure fluctuations and volume status, and can contribute to improved understanding of IOP changes during prone spinal surgery, which may in turn bridge the knowledge gap of the causes of POVL.
- Conditions
- Intraocular Pressure
- Being tested
- Contact lens sensor
- Keywords
- IOP
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Contact lens sensorDevice
Patient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface.
| Study group | Role | What they receive |
|---|---|---|
| Contact lens sensor | Experimental | Patient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface. Receives: Device: Contact lens sensor |
What is being measured
The primary outcome is the main question the study is designed to answer.
Report the physiological changes of IOP patterns during prone spinal surgery
The outcome measure will be to report the physiological changes of IOP patterns during prone spinal surgery.
Measured: 1 year
Secondary outcomes (2)
Correlate any intraoperative risk factors that may cause IOP fluctuations
To correlate any intraoperative risk factors that may cause IOP fluctuations
Measured: 1 year
Documentation of IOP changes after the surgery until the contact lens sensor is removed
Documentation of IOP changes after the surgery until the contact lens sensor is removed
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Oct 2017
- Study start9 May 2016
- Primary completion9 May 2017
- Study completion9 May 2017
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (11)Papers the sponsor has linked to this study.
- Other trials for Intraocular PressureStudies of the same condition, open and under way.
- More trials run by The University of Hong KongThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- All eligible patients who have given informed consent will attend the ophthalmology clinic for screening. Patient will undergo general anaesthesia for prone spinal surgery. The degree of inclination was set prior to the start of the case and independently confirmed using a goniometer. Patients will be placed in the prone position on a Jackson Spine table. Once positioned, the head is carefully placed on the GentleTouch prone positioning pillow of the appropriate size. Patient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface. The output of the sensor expressed in voltage, and can be analysed in real time points corresponding to the intraoperative events.
- Masking
- None (open label)
- Enrolment
- 10 participants (actual)
Sponsor and investigators
- Lead sponsor
- The University of Hong Kong
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dr. Kenny Kwan, The University of Hong Kong
- Investigators
- Dr Kenny Kwan, BMBCh(Oxon), Principal investigator, The University of Hong Kong
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03299400
- Sponsor's protocol ID
- UW 16-207
- Status last verified
- May 2020
- First submitted
- 27 Sep 2017
- Last updated
- 6 May 2020
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Carey TW, Shaw KA, Weber ML, DeVine JG. Effect of the degree of reverse Trendelenburg position on intraocular pressure during prone spine surgery: a randomized controlled trial. Spine J. 2014 Sep 1;14(9):2118-26. doi: 10.1016/j.spinee.2013.12.025. Epub 2014 Jan 20.
PubMed 24456677Sugata A, Hayashi H, Kawaguchi M, Hasuwa K, Nomura Y, Furuya H. Changes in intraocular pressure during prone spine surgery under propofol and sevoflurane anesthesia. J Neurosurg Anesthesiol. 2012 Apr;24(2):152-6. doi: 10.1097/ANA.0b013e31823fe822.
PubMed 22274735Yoshimura K, Hayashi H, Tanaka Y, Nomura Y, Kawaguchi M. Evaluation of predictive factors associated with increased intraocular pressure during prone position spine surgery. J Anesth. 2015 Apr;29(2):170-4. doi: 10.1007/s00540-014-1921-8. Epub 2014 Sep 24.
PubMed 25249431Deniz MN, Erakgun A, Sertoz N, Yilmaz SG, Ates H, Erhan E. The effect of head rotation on intraocular pressure in prone position: a randomized trial. Braz J Anesthesiol. 2013 Mar-Apr;63(2):209-12. doi: 10.1016/j.bjane.2012.03.008. Epub 2013 Aug 13.
PubMed 24565128Walick KS, Kragh JE Jr, Ward JA, Crawford JJ. Changes in intraocular pressure due to surgical positioning: studying potential risk for postoperative vision loss. Spine (Phila Pa 1976). 2007 Nov 1;32(23):2591-5. doi: 10.1097/BRS.0b013e318158cc23.
PubMed 17978659Setogawa A, Kawai. Measurement of intraocular pressure by both invasive and noninvasive techniques in rabbits exposed to head-down tilt. Jpn J Physiol. 1998 Feb;48(1):25-31. doi: 10.2170/jjphysiol.48.25.
PubMed 9538286Postoperative Visual Loss Study Group. Risk factors associated with ischemic optic neuropathy after spinal fusion surgery. Anesthesiology. 2012 Jan;116(1):15-24. doi: 10.1097/ALN.0b013e31823d012a.
PubMed 22185873Leonardi M, Pitchon EM, Bertsch A, Renaud P, Mermoud A. Wireless contact lens sensor for intraocular pressure monitoring: assessment on enucleated pig eyes. Acta Ophthalmol. 2009 Jun;87(4):433-7. doi: 10.1111/j.1755-3768.2008.01404.x. Epub 2008 Nov 12.
PubMed 19016660Mansouri K, Weinreb R. Continuous 24-hour intraocular pressure monitoring for glaucoma--time for a paradigm change. Swiss Med Wkly. 2012 Mar 28;142:w13545. doi: 10.4414/smw.2012.13545. eCollection 2012.
PubMed 22457163Parekh AS, Mansouri K, Weinreb RN, Tafreshi A, Korn BS, Kikkawa DO. Twenty-four-hour intraocular pressure patterns in patients with thyroid eye disease. Clin Exp Ophthalmol. 2015 Mar;43(2):108-14. doi: 10.1111/ceo.12400. Epub 2014 Sep 29.
PubMed 25132194De Smedt S, Mermoud A, Schnyder C. 24-hour intraocular pressure fluctuation monitoring using an ocular telemetry Sensor: tolerability and functionality in healthy subjects. J Glaucoma. 2012 Oct-Nov;21(8):539-44. doi: 10.1097/IJG.0b013e31821dac43.
PubMed 21602707
Study at a glance
From the registry record, last updated by the sponsor on 6 May 2020. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Continuous Intraocular Pressure Patterns in Spine Surgery
- ClinicalTrials.gov ID
- NCT03299400
- Acronym / sponsor ID
- UW 16-207
- Conditions
- Intraocular Pressure
- Keywords
- IOP
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 10 participants (actual)
- Lead sponsor
- The University of Hong KongUniversity, hospital or other
- Study start
- 9 May 2016 (actual)
- Primary completion
- 9 May 2017 (actual)
- Study completion
- 9 May 2017 (actual)
- First posted
- 3 Oct 2017 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Post-operative visual loss is a rare but serious complication after surgery. It is most significantly correlated with prone spinal surgery with a prolonged duration. The cause and risk factors are not elucidated, but the majority of the cases are due posterior ischaemic optic neuropathy (PION). This entity is directly related to the ocular perfusion pressure (OPP), which is estimated as the difference between mean arterial blood pressure (MAP) and intraocular pressure (IOP). Autoregulation is believed to maintain a constant perfusion to the optic nerve despite fluctuations in the perfusion pressure.
IOP is known to increase in the prone position thus putting susceptible patients at risk for inadequate ocular nerve perfusion. Most of the evidence comes from animal and healthy volunteer studies and cannot give an accurate insight into the subtle changes of intra-operative IOP. All the published studies employed the use of a tonometer, which may have rooms for measurement errors due to inadvertent pressure on the globe while retracting the eyelids, particularly when there is significant periorbital/conjunctival swelling in the prone position. The majority of the studies recruited healthy volunteers in a simulated surgical setting so other fluctuating parameters, which can affect intraoperative IOP, cannot be measured. In the few reports where patients undergoing surgery in the prone position were studies, IOP measurements were taken at non-continuous monitoring at time intervals, thus the effects of changes in blood volume, MAP, central venous pressure (CVP) and PaCO 2 could not be studied. Lastly, all the literature consists of case series only with no control group so the effect of position cannot be evaluated independently of the other factors.
The investigators therefore propose to conduct a prospective study with continuous intraoperative IOP monitoring to give us further insight into the physiological changes of IOP in patients undergoing spine surgery, and identify the risk factors related to fluctuations of IOP during prone spinal surgery.
Detailed description
Post-operative visual loss (POVL) is a rare but serious complication after surgery.
One of the known associations is prone spinal surgery with a prolonged duration.
The cause is not completely understood, but some of the risk factors for developing POVL include anaemia, hypotension, the duration of surgery and patient factors such as age, hypertension and atherosclerosis. There are also some unidentifiablerisk factors that may predispose young healthy patients to POVL. Once the patient develops POVL, it is usually irreversible, and the patient is left with a permanent disability.
The majority of POVL cases that occur with prone spinal surgery are due to posterior ischaemic optic neuropathy (PION). PION is directly related to the ocular perfusion pressure (OPP), which is estimated as the difference between mean arterial blood pressure (MAP) and intraocular pressure (IOP). Autoregulation is believed to maintain a constant perfusion to the optic nerve despite fluctuations in the perfusion pressure.
However, there is a knowledge gap in the physiological changes of IOP during prone surgery. IOP is a highly dynamic parameter, and the most widely used method to measure it is using a handheld tonometer. The main limitation of this technique is the isolated nature of its measurements, as it can only be taken at regular intervals, and may not reflect the full range of IOP changes. Studies on IOP during prone position in the current literature have all used this technique. 1-5 Hence subtle changes of IOP can be undetected, as interval measurements cannot reflect short-term variations that occur within seconds or minutes. Furthermore, most of the studies are performed on animals or healthy volunteers 5,6 , which further limit the interpretation of their results. For the few studies performed on anaesthetised patients undergoing spinal surgeries, the duration of surgery is short or mixed, so the critical time point may not have been studied. The American Society of Anesthesiologists Postoperative Visual Loss Registry suggests that an anaesthetic duration of greater than 6 hours is more correlated with POVL.
Using state of the art technology Over the past five years, advances in technology have led to the development of devices that allow 24 hour continuous IOP monitoring. The new system makes use of microelectromechanical systems, nanotechnology, and telemetry to allow continuous monitoring. A disposable contact lens sensor, first proposed by Leonardi et al. 8 , is now commercially available (SENSIMED Triggerfish; Sensimed AG, Lausanne, Switzerland). This technology can acquire data points over a 24 hour period corresponding to 30 seconds of continuous measurements. It measures changes in the ocular dimensions at the corneoscleral junction, which corresponds to changes to IOP and volume. The microprocessor within the lens transmits data to an external antenna, and the profiles can be stored in a portable recorder. 9 Although this sensor does not measure IOP directly, it gives measurements with a composite of IOP and volume changes, and it is most valuable in documenting relative changes of IOP-related events and their timing. It is also well tolerated in real life patients, and have been used to document IOP changes in patients with glaucoma and thyroid eye disease. 9-11 This is the only non-invasive temporary continuous monitoring in the system that can be used in human beings. This new technology is therefore ideal in detecting subtle changes in IOP pattern in prone spinal surgery. It will provide a continuous monitoring which can be correlated with the patient's level of anaesthesia, arterial pressure fluctuations and volume status, and can contribute to improved understanding of IOP changes during prone spinal surgery, which may in turn bridge the knowledge gap of the causes of POVL.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- All eligible patients who have given informed consent will attend the ophthalmology clinic for screening. Patient will undergo general anaesthesia for prone spinal surgery. The degree of inclination was set prior to the start of the case and independently confirmed using a goniometer. Patients will be placed in the prone position on a Jackson Spine table. Once positioned, the head is carefully placed on the GentleTouch prone positioning pillow of the appropriate size. Patient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface. The output of the sensor expressed in voltage, and can be analysed in real time points corresponding to the intraoperative events.
| Arm | Type | Receives |
|---|---|---|
| Contact lens sensor | Experimental | Device: Contact lens sensorPatient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Signed informed consent
- Age 18 to 80 years inclusive
- No pre-existing eye pathology (excluding refractive error), patients with glaucoma, history of eye injury or ophthalmic surgery
- No known allergy to contact lens material
- Patients undergoing anterior cervical spine surgery and prone spine surgery for duration of 3 hours or longer
Key exclusion criteria (3 listed)
- Unable to comply with follow up or give informed consent
- Cannot tolerate wearing contact lens
- Has active eye infection
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Contact lens sensorPatient will continue to wear the contact lens postoperatively for a total of 24 hours or until the patient cannot tolerate the contact lens. After removal of the contact lens sensor, the recorded profiles will be collected and visualized graphically on a computer interface. | Device | Contact lens sensor |
Primary outcome
Report the physiological changes of IOP patterns during prone spinal surgery
Time frame: 1 year
The outcome measure will be to report the physiological changes of IOP patterns during prone spinal surgery.
2 secondary outcomes
Correlate any intraoperative risk factors that may cause IOP fluctuations
Time frame: 1 year
Documentation of IOP changes after the surgery until the contact lens sensor is removed
Time frame: 1 year
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 May 2020.
- Background: PubMed 24456677Carey TW, Shaw KA, Weber ML, DeVine JG. Effect of the degree of reverse Trendelenburg position on intraocular pressure during prone spine surgery: a randomized controlled trial. Spine J. 2014 Sep 1;14(9):2118-26. doi: 10.1016/j.spinee.2013.12.025. Epub 2014 Jan 20.
- Background: PubMed 22274735Sugata A, Hayashi H, Kawaguchi M, Hasuwa K, Nomura Y, Furuya H. Changes in intraocular pressure during prone spine surgery under propofol and sevoflurane anesthesia. J Neurosurg Anesthesiol. 2012 Apr;24(2):152-6. doi: 10.1097/ANA.0b013e31823fe822.
- Background: PubMed 25249431Yoshimura K, Hayashi H, Tanaka Y, Nomura Y, Kawaguchi M. Evaluation of predictive factors associated with increased intraocular pressure during prone position spine surgery. J Anesth. 2015 Apr;29(2):170-4. doi: 10.1007/s00540-014-1921-8. Epub 2014 Sep 24.
- Background: PubMed 24565128Deniz MN, Erakgun A, Sertoz N, Yilmaz SG, Ates H, Erhan E. The effect of head rotation on intraocular pressure in prone position: a randomized trial. Braz J Anesthesiol. 2013 Mar-Apr;63(2):209-12. doi: 10.1016/j.bjane.2012.03.008. Epub 2013 Aug 13.
- Background: PubMed 17978659Walick KS, Kragh JE Jr, Ward JA, Crawford JJ. Changes in intraocular pressure due to surgical positioning: studying potential risk for postoperative vision loss. Spine (Phila Pa 1976). 2007 Nov 1;32(23):2591-5. doi: 10.1097/BRS.0b013e318158cc23.
- Background: PubMed 9538286Setogawa A, Kawai. Measurement of intraocular pressure by both invasive and noninvasive techniques in rabbits exposed to head-down tilt. Jpn J Physiol. 1998 Feb;48(1):25-31. doi: 10.2170/jjphysiol.48.25.
- Background: PubMed 22185873Postoperative Visual Loss Study Group. Risk factors associated with ischemic optic neuropathy after spinal fusion surgery. Anesthesiology. 2012 Jan;116(1):15-24. doi: 10.1097/ALN.0b013e31823d012a.
- Background: PubMed 19016660Leonardi M, Pitchon EM, Bertsch A, Renaud P, Mermoud A. Wireless contact lens sensor for intraocular pressure monitoring: assessment on enucleated pig eyes. Acta Ophthalmol. 2009 Jun;87(4):433-7. doi: 10.1111/j.1755-3768.2008.01404.x. Epub 2008 Nov 12.
- Background: PubMed 22457163Mansouri K, Weinreb R. Continuous 24-hour intraocular pressure monitoring for glaucoma--time for a paradigm change. Swiss Med Wkly. 2012 Mar 28;142:w13545. doi: 10.4414/smw.2012.13545. eCollection 2012.
- Background: PubMed 25132194Parekh AS, Mansouri K, Weinreb RN, Tafreshi A, Korn BS, Kikkawa DO. Twenty-four-hour intraocular pressure patterns in patients with thyroid eye disease. Clin Exp Ophthalmol. 2015 Mar;43(2):108-14. doi: 10.1111/ceo.12400. Epub 2014 Sep 29.
- Background: PubMed 21602707De Smedt S, Mermoud A, Schnyder C. 24-hour intraocular pressure fluctuation monitoring using an ocular telemetry Sensor: tolerability and functionality in healthy subjects. J Glaucoma. 2012 Oct-Nov;21(8):539-44. doi: 10.1097/IJG.0b013e31821dac43.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Dr Kenny Kwan, BMBCh(Oxon) principal investigator
The University of Hong Kong
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Contact lens sensor in people with Intraocular Pressure, run by The University of Hong Kong at 1 site in Hong Kong.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 May 2020. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Hong Kong. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Report the physiological changes of IOP patterns during prone spinal surgery (time frame: 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03299400, which also lists 11 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 May 2020.