Written by Randy Harvey, CRNA, BS

Since Dr. Atkinson described the retrobulbar block in 1936, orbital regional block techniques have continued to undergo refinements that have led to improved patient safety and comfort. The technique of utilizing a parallel approach to orbital blocks has been around for more than 30 years. Gills and Loyd described the technique in, AM Intra-Ocular Implant Soc. J-VOL , Summer 1983, titled "A Technique of Retrobulbar Block with Paralysis of Orbicularis Oculi." Directing the needle tip away from the vital orbital structures is this technique's primary value. Secondarily, the needle is inserted through the conjunctiva avoiding a skin puncture, reducing the potential for lid ecchymosis. 

The needle is inserted with the bevel towards the globe infero-temporally, above the inferior oribital rim, apporximately 3-5mm lateral to the lateral libmic margin of the globe, through the conjunctiva. The needle travels posteriorly, inferior to the globe. After passing the equatorial plane of the globe, the needle is redirected cephalad and advanced into the intra-conal compartment of the mid-orbit to a depth of approximately 25mm. The needle tip rests approximately 5mm posterior to the globe. 

The needle remains parallel to the visual axis and lateral to the lateral limbic margin throughout the technique. Therein lies the difference from the Atkinson needle based technique, which directs the needle tip towards the orbital apex. 

Anatomically, the needle tip rests in an area that has been described as a safe zone, relatively devoid of vital orbital structures. However, the eye should not look medial because it may place the optic nerve in line with the needle tip. In addition, a retrobulbar hemorrhage can still occur if the orbital veins in this area are traumatized. The general proximity of the vital orbital structures in relation to the pathway of the needle tip is illustrated below: 

1. Structures MEDIAL to the needle tip pathway:

Nerves
CN II Optic
CN III Oculomotor
CN IV Trochlear
CN V Trigeminal

Ciliary Ganglion/Nerves

Muscles
Superior Rectus
Inferior Rectus
Medial Rectus
Superior Oblique
Inferior Oblique

Vasculature 
Opthalmic Artery 
Central Retinal Artery
Ciliary Arteries
Superior Ophthalmic Vein
Central Retinal Vein
Venous Vortex Veins

2. Structures LATERAL ot the needle tip pathway: 

Nerves 
CN VI Abducens

Muscles
Lateral Rectus

3. Structures SUPERIOR to the needle tip pathway: 

Nerves
CN V Trigeminal/Lacrimal

Vasculature
Lacrimal Artery
Lacrimal Vein
Superior Ophthalmic Vein

4. The Globe's relationship to the needle tip pathway: 

Superior: The globe is superior to the needle tip, from its insertion point, until after the needle tip passes the equatorial plane of globe and is redirected  cephalad into the intraconal space. 

Posterior: The needle tip becomes posterior to the globe after passing the equatorial plane of the globe. 

Medial: The posterior pole of the globe (macula) remains medial to the needle tip throughout the procedure. Along with the area inferior to the macula where posterior staphylomas may form. 

As practitioners, we understand there is no anesthetic technique that is 100% safe. However, the parallel approach to orbital blocks incorporates a sound anatomical and technically safe approach for our needle tips to enter the intraconal space of the mid-orbit for the administration of the local anesthesia. 

Written by George A. Dumas, MD

Since cataract surgery is the most commonly performed operation in the geriatric population, it shouldn’t come as a surprise that this would be a target for payors of medical care.  Most notably, health insurer Anthem has recently stated that it is unnecessary to have an anesthesiologist or nurse anesthetist to administer and monitor sedation in most of these cases.¹ Let’s take a look at aspects of this procedure that have led us to this point.  The American College of Cardiology and the American Heart Association have categorized cataract surgery as a very low-risk procedure.² Cataract surgery is an avascular procedure and considered very low-risk for bleeding complication.  Regional needle blocks during routine use of antithrombotic therapies are generally safe provided that levels are in the usual therapeutic window.³ Most modern day cataract surgeries are performed under topical/intracameral local anesthesia with sedation.  Routine preoperative testing is unnecessary⁴ and the chance of dying from cataract surgery is estimated to be 0.014%.⁵ 

                It can be argued that the involvement of the anesthesia team has led to much of the perceived safety and low mortality rate in cataract surgery.  Many ophthalmologists still utilize needle blocks and sub-Tenon’s blocks for cataract surgery.  Complications may include brainstem anesthesia which will require immediate intubation and resuscitation of the patient.  Patient expectations are high and anxiety, pain, and fear during cataract surgery produce lower patient satisfaction scores.⁶ Sedation and analgesia are often used to supplement suboptimal local anesthesia.  Patient movement and eye block complications account for most of the closed claims for monitored anesthesia care during ophthalmic surgery.⁷

                In a discussion on this topic in Kaiser Health News, Dr. David Glasser, an ophthalmologist stated: “An ophthalmologist cannot administer conscious sedation and monitor the patient and do cataract surgery at the same time.”¹ Anthem states that anesthesia services may be covered for cases of medical necessity which includes: patients <18 years old, patients unable to cooperate or communicate, patients unable to lie flat, and complex surgery.  It should be noted that anesthesia services for cataract surgery are covered by Medicare.  An ophthalmologist will most likely be focused on the eye, not necessarily the patient’s vital signs, respiratory signs, and sedation.  Patient safety experts are concerned.  Leah Binder, president and CEO of the Leapfrog Group, stated that there are better ways for Anthem to save money than keeping anesthesiologists and nurse anesthethetists out of the OR.¹ Her suggestion: “How about identifying surgeons who have the highest complication rates, and letting patients know about them?”¹ This is sure to be a hot-button topic moving forward but as a wise anesthesiologists once told me, just because you can doesn’t mean that you should.

References

1. Andrews, M. Anthem Calls On Eye Surgeons To Monitor Anesthesia During Cataract Surgery. Kaiser Health News. Feb. 20, 2018. https://khn.org/news/anthem-calls-on-eye-surgeons-to-monitor-anesthesia-during-cataract-surgery/

2. Fleisher LA, Fleischmann KE, Auerbach AD, et al. 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014;64:e77-137.

3. Katz J, Feldman MA, Bass EB, et al. Risks and benefits of anticoagulant and antiplatelet medication use before cataract surgery. Ophthalmology. 2003;110(9):1784-8.

4. Schein OD, Katz J, Bass EB, et al. Study of Medical Testing for Cataract Surgery. The value of routine preoperative medical testing before cataract surgery. N Engl J Med. 2000;342(3):168-75.

5. Keay L, Lindsley K, Tielsch, et al. Routine preoperative medical testing for cataract surgery. Cochrane Database Syst Rev. 2012;3:CD007293.

6. Fung D, Cohen MM, Stewart S, Davies A. What determines patient satisfaction with cataract care under topical local anesthesia and monitored sedation in a community hospital setting? Anesth Analg. 2005;100:1644-50.

7. Bhananker SM, Posner KL, Cheney FW, et al. Injury and liability associated with monitored anesthesia care: A closed claims analysis. Anesthesiology. 2006;104:228-34.

It has been a long winter for many and it seems that finally the spring has arrived along with this newsletter. The Ophthalmic Anesthesia Society continues to grow and we welcome our new president, Tina Tran, MD, Johns Hopkins, who has actively been involved with OAS for a number of years. I wish her good luck in this new role and thank Eric Fry, MD, Fry Eye Associates, for his services.

In this edition of the newsletter, we are sharing expert tips on orbital block techniques from OAS Member Randolf Harvey. We are also tackling a hot topic in the ophthalmology circles -- the Anthem statement. OAS Member George Dumas, MD, offers a meaningful response to the idea that it is unnecessary to have an anesthesiologist or nurse anesthetist to administer and monitor sedation. 

I would also like to share a friendly reminder that now is the best time to register for the 32nd Annual OAS Scientific Meeting in Chicago (September 28-30, 2018).

Please register early and encourage your colleagues to join you. Our program is available online and there is an exciting selection of lectures and workshops this year!

If any of you are interested in writing such commentaries, case reports or articles for the newsletter, please email me or Melissa Graham.  Also, if you have any suggestions on improving the newsletter, please let me know.

With warm regards,

Dr. Vinodkumar Singh, MRCP, FRCA
University of Alabama at Birmingham
Editor, OASIS