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

April 17, 2013
January 31, 2014
February 2013
October 2014   (final data collection date for primary outcome measure)
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.
Same as current
Complete list of historical versions of study NCT01840215 on ClinicalTrials.gov Archive Site
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Study on the Impact of Ocular Anesthetic Procedures in Ocular Blood Flow
Impact of Topical, Retrobulbar and General Anesthesia in Ocular Blood Flow

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.

  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
Observational
Time Perspective: Prospective
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Probability Sample

primary care setting

Open Angle Glaucoma
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  • 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.
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruiting
120
October 2014
October 2014   (final data collection date for primary outcome measure)

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
Both
18 Years and older
No
Belgium
 
NCT01840215
S16022013
No
Universitaire Ziekenhuizen Leuven
Universitaire Ziekenhuizen Leuven
Not Provided
Principal Investigator: Ingeborg Stalmans, MD, PhD UZ Leuven
Universitaire Ziekenhuizen Leuven
February 2013

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP