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VETcpd - Ophthalmology Peer Reviewed surgery in dogs

Eyelid disease is a relatively common occurrence in general practice. The location and structure of the means that they can be the victim of a vast array of disease entities, the clinical management of which includes surgery in many cases. An understanding of the function of the eyelids is important before considering surgery. This article reviews the surgical management of canine lid masses and conformational abnormalities, predominantly entropion. Key words: Eyelid surgery, blepharoplasty, Hotz-Celsus, wedge resection

Introduction Katherine E L Manchip The eyelids in most of our domestic noxious stimuli applied to the eyelids, BSc(Hons) BVSc PGDipVCP species consist of a superior (upper), conjunctival or corneal surfaces. This reflex is subcortical, mediated by the MRCVS inferior (lower) and nictitating membrane (third eyelid). Although reasonably simple trigeminal nerve (afferent arm) and facial ECVO Resident in Veterinary in their anatomy, the eyelids perform a nerve (efferent arm). Ophthalmology at South range of vital functions. These include From superficial to deep, the eyelids consist Devon Referrals protecting the eye from physical injury of three layers with a number of adnexal Kat graduated from the University of and maintaining ocular surface health, specialisations, which vary slightly between Bristol in 2012, having also completed and therefore vision. The eyelids are species (Figure 1A). Haired skin forms an intercalated degree in Veterinary subject to a vast range of possible disease the outermost surface, which is thinner Conservation Medicine. She worked in entities. There are a variety of diseases and more pliable than skin in other loca- general small animal practice in London specific to the eyelids but, owing to their tions. Cilia line the outermost edge of the for four years before completing a location at a mucocutaneous junction, upper eyelid margin and serve a protective small animal rotating internship at the they can also be affected as part of a wider role. Below this are the skeletal muscles Royal Veterinary College (RVC). She is dermatologic or systemic disease process. responsible for blinking, which extend to a currently in the second year of an ECVO Eyelid diseases can be divided into the fibrous tarsal plate responsible for provid- Ophthalmology Residency at South traditional categories of congenital and ing structural rigidity and containing the Devon Referrals. developmental, traumatic, inflammatory Meibomian . The Meibomian glands South Devon Referrals and neoplastic but regardless of aetiology, open at the eyelid margin and their secre- South Devon Veterinary Hospital clinical management is almost always tion (meibum) forms the superficial lipid The Old Cider Works, surgical. This article will therefore focus layer of the pre-ocular tear film. When Abbotskerswell, Devon TQ12 5GH on the surgical management of some viewed collectively at the eyelid margin, common canine eyelid problems; eyelid the orifices form the surgical landmark Tel: 01626 367972 masses and simple conformational defects. known as the ‘gray line’ (Figure 1B). For information surrounding surgery Lining the inner surface of the eyelids is of the third eyelid, readers are directed the palpebral , which reflects to an earlier article by Rose Linn-Pearl at the conjunctival fornix to become the (VetCPD Journal, Vol 5, Issue 2, 2018). bulbar conjunctiva overlying the globe. The eyelids can be divided clinically into Anatomy and function four regions: the dorsal and ventral eyelid It is important to consider the anatomy margins, the medial and the and function of the eyelids before lateral canthus, collectively forming what is contemplating any surgery. The eyelids known as the . In most of perform numerous roles including: our veterinary patients the dorsal eyelid is • Protection of the eye from the largest and most mobile. The palpebral physical injury fissure is oval as a result of distinct liga- • Entrapment of foreign material before mentous attachments and opposing muscle it contacts the globe groups (Figure 2), which ensure normal • Limiting evaporative loss of eyelid opening and closing i.e. blinking. • Production of glandular secretions. The medial canthal ligament forms a rela- SUBSCRIBE TO VETCPD JOURNAL In addition, the blink reflex aids distribu- tively tight attachment between the medial tion of the preocular tear film and directs canthus and the underlying subcutaneous Call us on 01225 445561 drainage of tears toward the nasolacrimal tissues and periosteum. The lateral canthus or visit www.vetcpd.co.uk canaliculi to remove toxic waste. Blinking is more mobile, particularly in dogs, where may be elicited in response to tactile or the ligament is poorly developed and

Page 28 - VETcpd - Vol 6 - Issue 2 VETcpd - Ophthalmology mostly replaced by the retractor anguli oculi lateralis muscle. This relative laxity is A Levator palpebrae superioris muscle why conformational defects often affect Septum orbitale the lower lid and lateral canthal area. Müller's muscle Figure 2 summarises the function, innerva- tion and blood supply of the muscles of Orbicularis Fornix the eyelids. oculi muscle Eyelid examination When examining the eyelids a systematic approach is most helpful. Palpebral conjunctiva Haired skin • The first step, and perhaps the most Tarsal plate important, is to assess the eyelids at a distance i.e. in the waiting room, to get an idea of their true resting posi- Meibomian tion. Eyelid conformation is the result of a number of factors, including the anatomical relationship between the eyelid, and globe; size of the Gland of Moll orbit; eyelid length; stability of the Cilium lateral canthus; and facial musculature. Many dogs will develop blepharospasm (involuntary tight closure of the eyelids) distorting eyelid conformation when B handled around the face, especially those with painful chronic ocular conditions, as they will anticipate discomfort. The 'gray line' formed by the • The presence and nature of any ocular meibomian orifices discharge should be noted, as well as its Palpebral conjunctiva location. For example, mucus adhered to cilia/hairs contacting the cornea is an indicator that those hairs are causing The meibomian glands can be visualised through the Palpebral conjunctiva, perpendicular to the lid margin corneal irritation. Abnormalities of the cilia are summarised in Figure 3. • Blinking should be assessed. Is there Figure 1: A. The layers of the eyelid complete closure of the eyelids, or B. The eyelid margin lagophthalmos (inability to close the eyelids properly)? Levator palpebrae superious muscle (occulomotor nerve) and • A ‘hands on’ examination should be Müller's muscle (sympathetic) performed both with the naked eye and Levator anguli with a light source (+/- magnification) ocularis medialis B to assess the periocular skin. Particular muscle* B Frontalis muscle.* attention should be paid to the relation- ship of the upper and lower eyelid B margins to the globe. This should also Angularis A oculi vein Superficial be assessed with the head in various temporal artery positions. Both eyelid margins should be everted and examined closely to assess the Meibomian glands, palpebral conjunctiva, and the nasolacrimal puncta. The nasolacrimal puncta should be checked for number (there should be Retractor anguli Medial canthal A oculi lateralis four in total) and size. tendon muscle* • Assessing eyelid conformation – this Dorsal and ventral will be covered in more detail later in C palpebral artery the article but it is important that it is Orbicularis assessed both before and after, applica- oculi muscle* Malar artery Malaris muscle (dorsal buccal branch tion of a topical anaesthetic. *Innervated by the palpebral branch of the facial nerve of the facial nerve • An ocular examination should then be performed, including fluorescein Figure 2: Action, innervation and blood supply of the eyelids

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staining. Any corneal disease, such as ulceration, should prompt further exam- A C ination of the overlying region of eyelid in case a foreign body or ectopic cilium has been overlooked. Surgical principles and preparation The aim of eyelid surgery should be to preserve or restore the normal anatomical relationship between the eyelid margins B D and the tear film, thereby preserving eyelid function. The highly vascular nature of the eyelids promotes rapid healing but it also means that tissue should be handled gently and sparingly to avoid excessive inflammation. Conjunctiva heals particularly swiftly so this layer can be left to heal by second- Figure 3: Cilia and hair abnormalities of the eyelid ary intention, rather than risking suture A. Cross section of a normal upper eyelid. The normal cilia are positioned externally to the orifice material traumatising the corneal surface. B. Distichiasis – The cilium arises from within the Meibomian gland and exits the orifice. Preserving the integrity of the eyelid This can then contact the cornea. Note the adherent mucus, a typical sign of corneal irritation margin is crucial, and the ‘gray line’ of the C. Ectopic cilium – Arises from within the Meibomian gland and emerges through the palpebral Meibomian gland orifices is an important conjunctiva to contact the cornea, often perpendicularly surgical landmark. The figure-of-eight D. Trichiasis – Normal cilia or periorbital hair contacts the cornea as a results suture pattern is required when surgery of abnormal facial conformation e.g. facial folds or entropion involves a full thickness incision of the eyelid margin and magnification is usually commonly found on the upper eyelid than thickness wedge resection with a two- required. the lower. layer closure including a figure-of-eight Surgical preparation of the eyelids should Tumours of the Meibomian glands appear suture pattern at the eyelid margin can be gentle. Eyelid hair should be carefully be performed (Figure 5i). A four sided or clinically as black, grey, brown or pink removed using small, specific clippers. The ‘house-shaped’ resection achieves wider masses extending from the gland orifice. thin skin is easily traumatised, which may surgical margins for the equivalent length They frequently have an irregular or lead to increased swelling, irritation and of eyelid margin removed (Figure 5ii). For ‘cobblestone’ surface, and occasionally may self-trauma post-surgery. A bland ointment larger masses requiring removal of greater extend through the palpebral conjunctiva. can be applied to the ocular surface to than one-third of the eyelid margin, exci- They are easily ulcerated if traumatised. collect debris and hair during preparation sion will need to be combined with a lid Obstruction of the orifice can result in and should be removed before flushing the lengthening procedure such as a sliding glandular rupture and leakage of lipid region with a 1:50 dilution of povidone lateral canthoplasty (Figure 6) (Moore secretions into the adjacent tissue. This can iodine aqueous solution. A minimum of & Constantinescu 1997). Referral to a three minutes contact time is required and cause a marked inflammatory response specialist should be considered in these aims to prevent damage to the corneal and (peritumoural lipogranulomatous inflam- cases, especially in breeds with a tight lid conjunctival . Finally, the region mation) giving the tumour a falsely large conformation (e.g. Chihuahuas, Yorkshire should be flushed with 0.9% sterile saline. appearance (Labelle & Labelle 2013). Terriers and Pugs). Surgical excision is the mainstay of therapy Other eyelid masses that might be Eyelid masses for localised eyelid tumours, sometimes in encountered, and possibly mistaken for a Eyelid tumours are a relatively common combination with cryotherapy, and is typi- neoplasm, include a (an inspis- finding in dogs. A survey conducted by cally curative. It is important to examine sated Meibomian gland) and hordeolum Krehbiel and Langham (1975) classified the underside of the eyelid thoroughly as (a localised infection or ‘’). Chelazia 202 canine eyelid neoplasms by tumour what is visible at the eyelid margin is often are frequently incidental findings, but type and biologic behaviour. Sebaceous just the tip of the iceberg (Figure 4). The if causing corneal irritation or local gland tumours, papillomas and melanomas appropriate surgical technique is dictated inflammation, can be lanced and curetted were reported to comprise 82.1% of the by the size and location of the mass. The under sedation or general anaesthesia. A neoplasms examined with aim is to achieve complete resection whilst hordeolum, which is painful, may require tumours being the most common (44%). maintaining anatomic accuracy and this lancing but this should not be carried out Benign tumours (75.3%) were more is particularly important for the upper until the abscess is pointing. This can be frequently encountered than malignant eyelid which moves over a greater area encouraged by using warm compresses. forms (26.7%) and were generally smaller. of the cornea. Wherever possible tissue Lancing too early runs the risk of infection Metastasis was not observed. The average should be submitted for histopathological spreading to adjacent tissues so topical and age of dogs at presentation was eight evaluation. For smaller tumours (up to systemic should be administered years and tumours were slightly more one third or less of eyelid length) a full concurrently.

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