Study on the Impact of Ocular Anesthetic Procedures in Ocular Blood Flow

This study is currently recruiting participants. (see Contacts and Locations)
Verified February 2013 by Universitaire Ziekenhuizen Leuven
Sponsor:
Information provided by (Responsible Party):
Universitaire Ziekenhuizen Leuven
ClinicalTrials.gov Identifier:
NCT01840215
First received: April 17, 2013
Last updated: January 31, 2014
Last verified: February 2013
  Purpose

Anaesthetic procedures in ophthalmology surgery have been a subject rapidly evolving in the past decades. In this era of topical anesthesia for ocular surgery, anesthetic ocular blocks are still important when profound anesthesia and akinesia are required. It is therefore still a popular choice in many practices worldwide for glaucoma and vitreoretinal surgery.

When deciding for a retrobulbar block, the local injection of varying mixtures and volumes of fast-acting anesthetics (such as lidocaine) - with or without a vasoconstrictive agent (such as adrenaline) - coupled with Hyaluronidase have been the standard care to provide painless surgery while minimizing the possible risks such as increased intraocular pressure (IOP), brainstem anesthesia, toxic reaction and ocular blood flow changes. Considering this latter issue, there has been a number of anecdotal reports of orbital vascular occlusion following local anesthetic procedures. These iatrogenic-induced vascular dysfunctions have been also suggested to play a role in intra-operatory vision loss (a "wipe-out" phenomenon) in patients with advanced glaucoma.

The rationale for the use of epinephrine in retrobulbar anesthesia is to slow absorption of the anesthetic in general circulation and thus to achieve a longer effect in the orbit. However, studies on ocular blood flow after adrenaline-containing compounds have consistently showed a decrease in ocular blood flow, thus raising the issue of whether it should be used in patients with known vascular dysfunction, namely glaucoma patients. Nevertheless, there has been no study to verify this claim concerning the safety of non-adrenaline containing anesthetics.

Injecting a pre-determined volume of anesthetic compound behind the globe, regardless of its formulation has also been debated. The orbital pressure increase can lead to a number of adverse reactions, not only increasing IOP but also potentially decreasing vascular input by local compression. This may be of particular interest in cases where the orbital structures may be altered. In glaucoma for instance, there has been suggested optic nerve sheaths to be less elastic than in healthy individuals, potentially making this structure less compliant to outside compression. In addition, there has been suggested that a number of glaucoma medications (especially if long term usage is considered) can induce an irreversible lipodystrophy of the orbit. These more rigid orbital tissues could also impair the orbit's ability to deal with the iatrogenic increased volume.

As seen, the current concepts on the impact of ocular anesthesiology in the orbit and the vascular supply to the eye are limited to a small number of non-homogeneous studies. We aim to study this impact through a non-invasive, widely established ultrasound based method of ocular blood flow research (color Doppler Imaging). Potentially, our study could help determine a taylor-made choice of the anesthesiology procedure to apply to a specific patient, thereby advancing the current standard of care in ophthalmology.


Condition
Open Angle Glaucoma

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Impact of Topical, Retrobulbar and General Anesthesia in Ocular Blood Flow

Resource links provided by NLM:


Further study details as provided by Universitaire Ziekenhuizen Leuven:

Primary Outcome Measures:
  • Ocular blood flow change [ Time Frame: Participants will be followed for the duration of hospital stay, an expected average of 2 hours ] [ Designated as safety issue: No ]
    The investigators will test whether anesthetic procedures in ophthalmic surgery (topical, retrobulbar and general anesthesia) induce a change in retrobulbar blood flow. The difference in ocular blood flow velocities between pre and post anesthetic induction will be performed.


Estimated Enrollment: 120
Study Start Date: February 2013
Estimated Study Completion Date: October 2014
Estimated Primary Completion Date: October 2014 (Final data collection date for primary outcome measure)
Groups/Cohorts
Controls
Patients scheduled for elective ophthalmic surgery with no family history of glaucoma, an increased or asymmetrical cup/disc ratio or any other optic disc structural change (notching, disc hemorrhage) or an intraocular pressure (IOP) above 21 mmHg that could suggest possible glaucoma suspects.
Primary open-angle Glaucoma
Patients scheduled for an elective glaucoma surgery that present with a characteristic optic disc damage (based on cup/disc ratio, thinning of neuroretinal rim, notching, disk hemorrhages, etc.) and visual field defects, with at least one measurement of IOP of >21 mmHg required
Normal Tension Glaucoma
Patients scheduled for an elective glaucoma surgery that present with a characteristic optic disc damage (based on cup/disc ratio, thinning of neuroretinal rim, notching, disk hemorrhages, etc.) and visual field defects, with at maximum recorded IOP of < 21 mmHg.

Detailed Description:
  1. Ultrasound B-mode scans will be performed before and after the anesthetic procedure
  2. Doppler scan will be added to the B-mode ultrasound to register the blood flow pattern of the ophthalmic and central retinal arteries
  3. Blood pressure and heart rate will be monitored
  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population

primary care setting

Criteria

Inclusion Criteria:

  • individuals over 18 years old
  • willing to sign an informed consent and able to comply with the requirements of the study

Exclusion Criteria:

  • history of ocular trauma
  • previous extraocular surgery
  • ocular disease other than the one motivating surgery
  • systemic diseases with ocular involvement like diabetes or Graves Ophthalmopathy
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01840215

Locations
Belgium
KU Leuven Recruiting
Leuven, Vlaams-Brabant, Belgium, 3000 Leuven
Contact: Luis Pinto, MD, PhD       abegaopinto@gmail.com   
Principal Investigator: Ingeborg Stalmans, MD, PhD         
Sub-Investigator: Evelien Vandewalle, MD, PhD         
Sub-Investigator: Luís Pinto, MD, PhD         
Sponsors and Collaborators
Universitaire Ziekenhuizen Leuven
Investigators
Principal Investigator: Ingeborg Stalmans, MD, PhD UZ Leuven
  More Information

No publications provided

Responsible Party: Universitaire Ziekenhuizen Leuven
ClinicalTrials.gov Identifier: NCT01840215     History of Changes
Other Study ID Numbers: S16022013
Study First Received: April 17, 2013
Last Updated: January 31, 2014
Health Authority: Belgium: Ethics Committee

Additional relevant MeSH terms:
Glaucoma
Glaucoma, Open-Angle
Ocular Hypertension
Eye Diseases

ClinicalTrials.gov processed this record on August 26, 2014