June 9, 2022

Dr Tim eye injection anatomy

As well as regularly treating his own patients, Dr Tim Pearce is well known as a trainer and opinion leader in medical aesthetics, offering a variety of online e-learning, training courses and masterclass events at SkinViva Training.

He is regularly asked for his thoughts and advice on many practical aspects surrounding treatment delivery with cosmetic injectables like dermal fillers and botulinum toxins, plus the avoidance of complications, much of which he shares on his social media feeds and in the regular Aesthetic Mastery Shows on YouTube and Spotify.

In this blog, Dr Tim will be answering commonly asked questions about botulinum toxin (Botox®) procedures.

Do you feel anxious about causing complications? Many clinicians feel so overwhelmed with the thought of causing a vascular occlusion that it stops them growing their aesthetics business. Dr Tim is currently hosting a webinar series to help you overcome your fear of complications so that you can uplevel your knowledge, and increase your CPD-certified learning to build a successful aesthetics business. Sign up here >>

With long term, regular use of botulinum toxin, is it strange that a patient would require a higher dose?

The short answer is no; this is something that you will notice with a small percentage of your patients over time. The reason why is somewhat unknown, but the working theory is that some patients develop a degree of resistance to the toxin with prolonged use, whilst others may achieve results for longer and longer periods of time with each subsequent use.

If you have a patient in the unhappy group where they get less time in between the need for repeat treatment, then it is mostly likely down to their immune system reacting and dampening the effects of the botulinum toxin.

You can either give your patient a break from wrinkle relaxing treatment, that could be up to a year, which they may not be pleased to hear, or you can try a different botulinum toxin brand. Dr Tim finds that switching products can be effective in around half of cases. Alternatively, you can try a higher dose of the existing toxin, until that becomes too expensive for both you and the patient.

How long can you keep reconstituted botulinum toxin in the fridge before it no longer works?

If you look at manufacturer guidance on this, they usually state that you have 24 hours to use the product, and that you should discard it within 24 hours. This advice is not based on product efficacy, but on the principle that once something is opened, it should not be left, and it is safer for patients if it is discarded in favour of a fresh vial.

Given the expense of botulinum toxin, this is not practical in clinical practice, so multiple studies have tested storage and product efficacy.

Results show that Botox is surprisingly resilient and can be up to 95% as efficacious as a fresh vial up to 6 weeks after dilution and storage in the fridge. Dr Tim advises that you should review the data yourself to satisfy your own knowledge, and ensure you follow best practice safety and sterility protocols. If you use bacteriostatic saline and sterile injection techniques, there is a low risk of causing an infection with a vial of reconstituted botulinum toxin that has been stored appropriately in the fridge for several weeks.

Why is there more resistance when injecting botulinum toxin superficially into the corrugators?

If you are injecting the corrugators correctly, you should be injecting relatively deep medially and becoming more superficial towards the tail of the corrugator as your insertion point is just above the mid-pupillary line. At this point, your needle is moving into the dermis, and you are no longer purely intramuscular, you are within the fibres of the muscle where they are meshed in with the dermis. This is a denser area, so it is harder for the tissue to expand to allow the ingress of the product. But when you are deeper, in the belly of the muscle, there is more room within those muscle fibres for expansion and product acceptance.

Does Dr Tim use different brands of botulinum toxin and how does he choose between them?

Forehead Botox Frontalis Injection SitesLike many aesthetic clinicians, Dr Tim initially, upon starting his career in aesthetic medicine, chose his botulinum toxin based on price – choosing the one that worked, was licensed for use, and cheaper than others on the market.

With years of experience under his belt, he started to realise that some patients became resistant to his toxin of choice, so he began to try different brands, and in doing so became aware of the nuances in performance and results. The variations in dilutions, the control afforded to the practitioner, and the reliability of one brand over another, were all factors that he started to consider.

Dr Tim’s botulinum toxin of choice is Botox® by Allergan Aesthetics, however, he believes that for the average aesthetic injector there is not a vast difference between the botulinum toxins licensed for cosmetic use in the UK.

Aside from the products themselves, it is worth looking into the support that you may receive from the different pharmaceutical companies behind the brands if they know that you are buying and using their products.

How do you avoid brow asymmetry when treating the glabella or frontalis with botulinum toxin?

Firstly, let us remind ourselves which muscles are controlling the position of the brow. There is a dynamic contest between the muscles – the glabella pulls medially and slightly downwards, procerus pulls the medial aspect downwards, and orbicularis oculi pulls the brow downwards, but frontalis pulls the brow upwards, and is probably the most important muscle to understand.

When you are treating the glabella, you have a small risk of affecting the frontalis, particularly laterally where it is most sensitive to causing asymmetry. Similarly, if you are treating the frontalis asymmetrically you are going to get asymmetrical brows – the key to understanding this is in the amount of muscle you are leaving untreated in each area of the frontalis; the larger the untreated area, the more the eyebrow will be supported, or even lifted, whilst the smaller the area left untreated, the more chance you have of it slumping downwards or looking heavy as it will certainly move less easily.

All the injections we perform, particularly at the mid-pupillary line and lateral in the forehead have powerful effects on the eyebrow because that is the area of the frontalis muscle that most directly affects eyebrow positioning.

Neatness is the key, ensuring symmetrical placement at the right depths, and avoiding the undesirable areas of frontalis. Dr Tim surmises that 70% of the risk of asymmetry surrounds injection neatness around frontalis and the remaining 30% is around the corrugators and orbicularis oculi.

How do you know how many units of botulinum toxin to inject to avoid over or undertreating?

forehead frown linesFor most areas of the face there are now licensed doses for the cosmetic use of botulinum toxins, such as Botox®. For the forehead, it is 20 units, the glabella is 20 units, and in the orbicularis oculi it is 24 units. This gives you a starting point for your treatments on how much to inject for your individual patients.

With greater experience, you will start to determine individualised dosing plans as you understand whether your patients’ faces have areas that are very strong, medium, or weak.

For example, if a patient has a very strong glabella, you may choose to use more than the licensed dose, increasing to 28-32 units, or even higher in some cases. If the area is weak, you may wish to reduce the dose to around 12 units to achieve the same result as you would with the licensed dose.

The licensed dosing can be seen as a median option, with some patients needing more and some needling less.

How do you inject a very small forehead with botulinum toxin without causing a brow drop, and preferably causing a brow lift?

This is a challenging situation, notes Dr Tim, because a small forehead means a small frontalis muscle, and consequently treating a little of the muscle is likely to cause a drop. This leaves little room to make that muscle lift the eyebrow. However, the same principles apply as they would to any forehead, but you must adjust your dose accordingly.

In practice, and as taught by Dr Tim, you would usually leave a 2cm safety margin from the eyebrow with a normal sized forehead. This method usually leaves two thirds of the forehead available to treat. With a smaller forehead you use 50% of the forehead which still takes up a significant portion, but you will find that you only have a small area to treat, higher up, with usually one line of 2, 3, or 4 injections, in contrast to a double line of injections with a larger forehead. With this approach, you are leaving more muscle proportionately untreated, but when compared to someone with a normal sized forehead you still see a similar amount of muscle untreated; the treated area is smaller because the forehead is smaller.

How deep should you inject the depressor angularis oris when injecting botulinum toxin?

The depressor angularis oris (DAO) muscle runs just underneath the hypodermis – there is a skin layer, superficial fat pads, and then the muscle.

Dr Tim recommends palpation of the muscle on both yourself and your patients – asking them to contract the area – so you get a true understanding of the depth of the muscle under the skin. Routinely checking your patients’ anatomy will increase your understanding of how deep the fat pad is in most people, although everyone is different, so treat everyone as an individual. You are aiming for the muscle itself, somewhere near the surface or within, but ideally not underneath the DAO, so avoid going too deep with your injections – practice and patient examination will increase your skill.

You can find Dr Tim Pearce on Instagram if you have a question on Botox treatments that you want him to answer, or if you have any other burning questions or comments about aesthetic practice..

Aesthetics Mastery Show

Your Botox Questions ANSWERED!

Treating a small forehead | Correct dosage | Avoiding Brow Asymmetry

To find out more, watch the Aesthetics Mastery Show, where Dr Tim shares his advice on how he would treat a small forehead with Botox without causing a lid droop, as well as other commonly asked Botox questions such as how to avoid asymmetry and how to determine the correct dosage.

Response from Botox® Practitioners

The show has had thousands of views and has prompted response and debate from aesthetics professionals. Some of the latest comments include:

“Dr Tim – this video is awesome and so helpful – I am super grateful to you for making this video – this has covered so many areas that us injectors need to know and given me even more confidence to treat patients effectively – thank you so much! 🙂”

Dr Robina Jan

“This was great information! Do you use different reconstitutions for treating different areas of the face and if so how does this affect the spread? Thank you for sharing all your knowledge!”

Carrie Haugen Reinhart

A new practitioner asked:

“Hey Dr Tim, I’ve recently completed my foundation training, for Toxin type A. But I’m really nervous about doing my first client on my own. In case I use the wrong amount of units & I’m so scared of giving someone a Spock brow lol any advice. Thank you 🖤”

Natalie McIntyre

Dr Tim’s Clinical Advisor replied:

“There is no harm in giving someone a Spock brow. It’s very easily rectified after 2 weeks with a simple unit above that Spock. Follow your notes and practice marking up on friends and families. Watch our free videos too, breathe and try not to worry. Better a Spock than a drop. And drops often come from treating too low so mark out those safety margins. Don’t let your nerves put you off trying. Get on that horse and have a go!

Kind regards Mary. Clinical advisor for Dr Tim.”

Read more and join in the debate on our YouTube channel.

BOTOX® / Botulinum Toxin eLearning

One way in which practitioners can improve their skills is to invest in training. If you’re a medically qualified aesthetic clinician, then eLearning courses could be a great way to support your learning. Dr Tim Pearce has created a pair of courses which provide foundation knowledge and complications training for botulinum toxin. Find out more about the courses together with a list of modules at:

In addition, browse our FREE downloadable resources and access FREE eLearning by following Dr Tim on social media.

Is your worst nightmare causing a VO?

If you want to be a great injector then you need to get over your fear of complications. Register here for the next webinar to help you overcome your complications anxiety >>

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Dr Tim Pearce eLearning

Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.

Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.

Thousands of delegates have benefited from the courses and we’re highly rated on Trustpilot. For more information or to discuss which course is right for you, please get in touch with our friendly team.


Botox® is a registered trademark of Allergan Aesthetics plc.

Comments (3)

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