Ophthalmologic Applications of Botox

Introduction

Botox (botulinum toxin) is an injectable neurotoxin derived from an anaerobic, spore-forming, gram-positive bacillus, Clostridium botulinum. There are eight stereotypes (A to H) of Clostridium botulinum, of which A and B types are used clinically. Botox has been used for ophthalmologic and neurologic disorders for over twenty years. The effect of these injections lasts for four to six months.

Botox is effective in treating dynamic wrinkles on the face, which gives a youthful appearance without undergoing surgical procedures. Though the effect is temporary, the therapeutic effects remain the same even after repeated injections. Complications are rare and do not last long. Most complications occur due to weakness of adjacent muscles, improper injection techniques, or immunologic reactions.

How Does Botox Work?

Botox inhibits the release of acetylcholine at the neuromuscular junction. This results in muscular paralysis. The toxin is composed of heavy and light chains. The heavy chain binds to specific receptors at the motor nerve endings, and the toxin gets internalized. The acidic pH within results in the dissociation of the light chain from the toxin. This dissociated light chain cleaves a specific protein complex responsible for the release of acetylcholine. As the protein complex gets cleaved, the release of acetylcholine does not take place. The effect of Botox starts within 24 to 72 hours and reaches peak effect in 7 to 14 days.

What Are the Preparations Before Botox Injections?

The following things are considered before the Botox injection:

• A 1 mL syringe with a 30 gauge needle is preferred.

• Before injection, the area is cleaned with an alcohol-free antiseptic solution.

• Topical creams containing a combination of Prilocaine and Lidocaine are used to reduce pain sensation.

• The skin is stretched to reveal superficial blood vessels to be avoided during the injection.

What Are the Ophthalmologic Applications ?

The applications of Botox include the following:

• Facial Wrinkles:

Lines noticeable during movement are called dynamic wrinkles, and those lines visible during rest are called static wrinkles. Botox interferes with muscle contraction, causing muscle relaxation and thereby eliminating wrinkles. Botox spreads to an area of 0.9 to 1.18 inch around the injection site. Botox type A is effective for aesthetic purposes when used in the middle and lower face.

• Crow’s Feet (Periorbital Wrinkles):

Wrinkles originating from the lateral canthus (outer corner of the eye) during smiling and laughing are called periorbital wrinkles or crow’s feet. Botox injections are made one centimeter from the lateral margin of the orbit (bony wall of the eye). Injecting too far from the lateral margin cause superior eyelid ptosis(drooping eyes), and injecting too below causes zygomatic muscle paralysis (paralysis of the zygomatic muscle) and lip ptosis (dropping of the lip).

• Strabismus (Crossed Eyes- Eyes Point in Different Directions):

Botulinum toxin A injections are used as an alternative to strabismus surgery for pediatric esotropia (one or both eyes turned inward). Studies show 70 % of cases of esotropia resolve with Botox. Electromyographic guided needle placement is used to ensure delivery to the intended muscle. In traumatic paralytic strabismus patients also, Botox is used to minimize contracture of opposing muscles till recovery.

• Nystagmus (Involuntary Repetitive Eye Movement):

Botox injections are applied to the horizontal rectus muscle or retrobulbar area for treating nystagmus. In some cases, retrobulbar injections reduce nystagmus but in some other cases, favorable results were not obtained.

• Benign Essential Blepharospasm:

This condition causes frequent, involuntary contraction of the orbicularis oculi muscle that results in forceful closure of the eye. Involuntary eye closure can lead to functional blindness. It is more common in females. Botox injections are made into the orbicularis oculi muscle below the skin.

• Lacrimal Gland Hypersecretion:

Lacrimal gland hypersecretion is a condition in which there is excessive tear production (crocodile tear syndrome). Botulinum type A toxin injections are found effective in such cases. Botulinum is injected directly into the palpebral lobe of the lacrimal gland (tear gland in the eye). The effects last for six months.

• Entropion (A Condition in Which Eyelids Are Turned Inward):

Botox injections can be used in cases of congenital and acquired entropion. Botox is injected three to four millimeters below the lower eyelid margin.

• Upper Eyelid Retraction:

Botox injections are used for a temporary cure of upper eyelid retraction. Transconjunctival injections are used in this condition. But there is a risk for complications like ptosis (drooping of upper eyelids over the eye) and diplopia (double vision).

• Facial Paralysis:

Botox injections are given to the levator palpebrae superioris muscle for treating facial paralysis. The injection prevents corneal damage in such cases by inducing eyelid ptosis.

• Hemifacial Spasm:

Hemifacial spasm usually starts at the age of 40 to 60 years, and the condition is bilateral in most cases. The condition continues even during sleep and is characterized by the contraction of facial muscles. Botox injections are used in such cases too.

What Are the Contraindications?

Botox injections are contraindicated in the following cases:

• Pregnancy.

• Lactating mother.

• Children below 12 years.

• Those patients who have allergic responses to components used in preparations.

• Patients having multiple sclerosis (an autoimmune chronic condition that affects the central nervous system).

• Patient with myasthenia gravis (an autoimmune neuromuscular condition characterized by skeletal muscle weakening).

What Are the Complications?

The complications associated with Botox injections are:

• Ptosis (drooping of upper eyelid).

• Dry eye.

• Eyebrow ptosis.

• Eyelid ptosis.

• Epiphora (watery eyes).

• Blurred vision.

• Mild pain.

• Headache.

• Edema (swelling).

• Bruising.

• Hemorrhage.

• Diplopia (double vision).

What Are the Precautions That Can Reduce Complications?

The complications associated with Botox can be reduced by taking the following precautions:

• The risk of hemorrhage can be reduced by asking patients to discontinue anticoagulant therapy two weeks prior to the procedure (on recommendation by the patient’s physician).

• Avoid touching or massaging the injected area for two hours following the procedure. This will increase the absorption of Botox.

• Increase the concentration and reduce the volume of Botox injections. This will prevent the diffusion of Botox to another adjacent unintended muscle site.

Conclusion

Botox is a safer and more effective treatment option for various neurologic and ophthalmic conditions like nystagmus, strabismus, blepharospasm, entropion, etc. Though the duration of the effect is shorter, the associated complications are rarer. And the effectiveness remains almost the same even with repeated administration. Botox is an effective and safer non-surgical alternative for correcting facial wrinkles and many ophthalmologic conditions.