Minimally Invasive Oculoplastic Surgery

1.1 General Points

Although the term “minimally invasive” has now entered medical vocabulary, the concept of doing the smallest intervention that has the greatest effect with minimum collateral damage is the basis of good medical practice. Many minimally invasive procedures in lid surgery have been established for decades, some of which have enjoyed a renaissance, whereas others are relatively new [37, 60, 61]. The examples described here are performed under vasoconstrictive local anaesthesia (e.g. bupivicaine 0.5% with adrenaline 1:100,000) unless otherwise indicated. All of these procedures aim to keep morbidity and recovery time of the patient to a minimum.

The surgical anatomy of the lids divides them into anterior and posterior lamellae, the anterior lamella consisting of skin and orbicularis and the posterior, of tarsal plate and conjunctiva. The grey line of the lid margin is the demarcation anterior to which is the squamous epithelium and the lashes, and posterior to which is the conjunctiva pierced by the openings of the tarsal meibomian glands (Fig. 1.1).

The upper and lower lids are retracted by the levator palpebrae superioris/Muller’s muscle complex and inferior retractors respectively. The latter are a fibrous sheet extending from the inferior rectus muscle sheath to the inferior border of the inferior tarsus, with a few slips of smooth muscle similar to Muller’s muscle. This sheet splits to enclose the inferior oblique muscle which runs across it (Fig. 1.2).

1.2 Lower Lid Entropion

1.2.1 Introduction

The term entropion comes from the Greek words en (towards) and tropein (to turn), and describes the turning in of the lid margin towards and onto the globe. The two main categories of entropion are involutional and cicatricial, with involutional being by far the most common. Natural ageing changes of the lid tissues express themselves as laxity. In the vertical plane, disinsertion of the lower lid retractor attachment to the inferior border of the tarsal plate (equivalent to aponeurosis dehiscence of the levator in the upper lid)

weakens its power. Weakness of the lower lid retractors is considered to be the most important contributor to the development of entropion; the horizontal plane is lengthened by stretching of the canthal tendons and some atrophy of the tarsus [11, 13, 38]. These changes allow slippage and instability of the usual anatomical relations of the lamellae, with the preseptal orbicularis riding up, thus tipping the lid margin inwards (Fig. 1.3).

1.2.2 Lower Lid Entropion Sutures

Formal surgical procedures address the weakened attachments of the retractors, the horizontal laxity and the overriding orbicularis – ideally all three [19]. However, it is possible to temporise with a minimally invasive procedure, particularly if there is little or no horizontal laxity. Sutures were known to be in use at the time of Hippocrates [9]. Two types are distinguished. Transverse sutures are placed horizontally through the lid (from the base of the tarsal plate and out onto the skin) so as to form a barrier to prevent the upward movement of the pretarsal orbicularis. Everting sutures are placed at an angle so as to bring the lower lid retractors up to the tarsal plate and use their power to pull the lid margin forward [20, 61].

Fig. 1.3 Preseptal orbicularis over ride in entropion. Illustration by Christiane Solodkoff, Neckargemünd/Heidelberg, Germany

Patient selection: sutures depend on the scarring they create and leave behind once they have dissolved or been removed. It is the scarring that holds the lid in its new corrected position. The less severe the involutional entropion, the longer the effect will last. It may last many months, possibly even years, in a patient with intermittent entropion with little or no lid laxity,

i.e. before the ageing changes have a chance to worsen horizontal laxity and lamellar slippage. It is these continual ageing changes which lead to recurrence. Sutures alone will have little or no long-term effect on cicatricial entropion and their use alone would be inappropriate in such cases; here, the scarred and shortened posterior lamella would need to be corrected.

Correct placement of the suture: to overcome the anterior lamellar override caused by the preseptal orbicularis pushing the lid in, three or more doublearmed sutures are placed transversally across the full thickness of the lid, at a level just below the inferior border of the tarsus (Fig. 1.4a). The everting sutures need to pick up the detached lower lid retractors and pull them upwards and forwards so they can pull the tarsus outwards. The vector of pull needed to restore normal margin position is from low in the posterior lamella to high in the anterior lamella (Fig. 1.4b). This is also achieved by using three or more double-armed 4/0 sutures entering the conjunctiva below the inferior border of the tarsal plate, to catch the retractors. The needles are pushed forwards and superiorly to exit the skin below the lash line anterior to the tarsal plate and the sutures are tied. The exit points on the skin are much higher than the level of entry on the conjunctival surface, and above the preseptal orbicularis. How far below the inferior border the sutures enter the conjunctiva depends on the degree of entropion which is related to how far the retractors have dropped. The more the anterior rotation required, the lower is the suture entry posteriorly. For mild rotation, the entry is made 3–4 mm below the inferior border of the tarsal

a

Fig. 1.4 Entropion sutures. (a) Transverse suture; (b) everting suture. Illustration by Christiane Solodkoff, Neckargemünd/ Heidelberg, Germany

plate. If the entropion is more severe, so is the laxity of the lower lid retractors; the needle entry is therefore made lower at 8–10 mm below the inferior border of the tarsal plate.

Correct type of suture: a suture which produces a minimal reaction from tissues such as nylon can be used if the temporising measure is only for a matter of days, or weeks at the most, with the intention of proceeding to formal surgical correction of the entropion. If, on the other hand, the procedure is intended to last longer, then a suture which generates an inflammatory response, such as silk catgut or Vicryl, will be more effective, as the resulting scar will outlive the sutures once these have been removed or fallen out. Postoperatively, patients are treated with topical antibiotics for a week. The sutures loosen within 3–4 weeks, after which they can be removed. Their removal prior to this time should be avoided so as to allow fibrosis to establish itself.

1.2.3Lower Lid Entropion Botulinum Toxin

This toxin is the most powerful and lethal poison known to man, with a median lethal intravenous dose of 1ng/kg [3]. It was originally introduced in ophthalmology over 25 years ago as an alternative to surgical treatment of strabismus and its safety in this field and for idiopathic blepharospasm was recognised early [62, 63]. Botulinum toxin A is one of seven antigenically distinguishable

b