Fundamentals of Intravitreal Injections

The following sections are included:

• CONTENTS
• ABOUT THE AUTHORS
• FOREWORD
• ACKNOWLEDGEMENTS

Age-related macular degeneration is the commonest cause of visual impairment registration in the UK. Intravitreal injections (injections into the vitreous gel of the eye) of antivascular endothelial growth factors (anti-VEGF’s) such as Lucentis^® (ranibizumab), Avastin^® (bevacizumab) and Eylea^® (aflibercept) are now widely accepted to reduce the progression of “wet” macular degeneration. There is also good evidence of their efficacy in macular oedema secondary to diabetes and vein occlusions…

In order to be proficient in intravitreal injections, it is crucial to appreciate the structure of the eye and how this knowledge can be used to give a safe injection.

The eye is a highly specialised organ of photoreception. This is a process by which light energy from the environment produces changes in specialised nerve cells in the retina (rods and cones). These changes result in action potentials (the electrical voltage across a cell) that are subsequently relayed to the optic nerve and then to the brain, where the information is processed and consciously appreciated as vision…

Every patient presenting for an intravitreal injection will have gone through an investigative process in the clinic. The ophthalmic nurse practitioner will inevitably come across the results of these patients either in the clinic or whilst looking through the notes prior to injection. Also, nurse practitioners are now increasingly reviewing patients in clinics and may in the future be an integral part of “virtual” clinics where they will carry out investigations at a peripheral site and the clinician will review the results in the hospital. Therefore, an understanding of the basic investigative techniques employed is beneficial. Here we discuss the essentials of optical coherence tomography and fundus fluorescein angiography, alongside an introduction to new modalities such as optical coherence tomography angiography and ultra-widefield fundus imaging.

There are three common macular problems, which often require regular intravitreal therapy:

• Wet age-related macular degeneration (AMD)–choroidal neovascular membrane (CNVM);
• Diabetic macular oedema (DMO);
• Retinal vein occlusion (RVO) with macular oedema…

The following is based on published guidance to reflect the latest clinical practice. There may be minor inter-departmental variations, although the general principles remain the same…

The reason why patients give their informed consent for an intravitreal injection is that, on balance, they perceive that the potential benefits of treatment outweigh the risks.

As with any surgical procedure, there is potential for complications at any stage and it is important for the practitioner to be aware of these.

Recently many innovative devices have become available on the market for precise and efficient delivery of intravitreal injections. To varying degrees, they obviate the need for a drape, speculum and calliper, thus making the injection process not only more comfortable for the patient but also safer in the hands of the practitioner.

Proceeding with a specialised role can often be a daunting decision for nurses to make. However, once the decision has been made there may be further challenges ahead. In areas where nurses have only recently started to take on extended roles, training structures can be lacking. Intravitreal injection training at present has no defined curriculum by either the Royal College of Nursing or the Royal College of Ophthalmologists. It is thus left to the individual department to try to forge a training structure, which can be time-consuming. Here we outline a scheme we have used in our region over the last few years. The reader can feel free to adopt it in its entirety or modify it to suit their departmental needs. In our experience, both trainers and trainees have found it relevant and easy to undertake.

Organising a wetlab session can be invaluable for training to do intravitreal injections. This can easily be done by following the steps below:

• Supervised “mock” intravitreal injections on pigs’ eyes are performed as per the technique described earlier.
• Split pig heads (split down the middle, as shown in Figs. 9.1 and 9.2) can be easily acquired from your local butcher. We have used them very successfully in local courses for ophthalmologists and to train our nurse practitioners as well.
• The pigs’ heads should be kept in a tray (as shown) to avoid spillage of fluids used.
• The complete procedure can be easily practised, starting from draping all the way through to giving the injection.
• Special care should be taken to dispose of the anatomical waste (i.e. pigs’ heads). Most hospitals require the use of yellow bin bags that have to be placed in special clinical waste collection areas. Do consult your hospital’s clinical waste disposal team for specific instructions.

Intravitreal injections may be carried out in a theatre or in a dedicated clean room for outpatients. The volume of injections required on a daily basis in most eye units has led to the vast majority being done in outpatients. Whilst organising a clean room one must keep in mind the following precautions:

• The room should deal only with non-infected cases and be free from interruptions. Check with your local infection control team regarding the exact specifications of a clean room in your hospital.
• The room must have good illumination and washable floors (as confirmed by local health and safety regulations).
• The ceiling should be non-particulate in nature, so that no dust or debris can fall onto the operating field.
• Resuscitation facilities should be available nearby. The room should also have a reclining chair or a bed with an adjustable incline, so as to be able to change the patient’s position in case an emergency occurs.

The following sections are included:

• FURTHER READING
• APPENDIX A: INTRAVITREAL INJECTION CHECKLIST
• APPENDIX B: BASIC LIFE SUPPORT ALGORITHM (RESUSCITATION COUNCIL, UK, 2015)
• APPENDIX C: ANAPHYLAXIS ALGORITHM
• INDEX