Chapter 57 - Adnexal surgery Flashcards
1
Q
What are the adnexa of the eye?
A
Eyelids, conjunctiva, nictitating membrane, and nasolacrimal system.
2
Q
What type of sensation initiates reflex blinking?
A
Tactile sensation.
2
Q
Name two glands associated with the eyelid cilia.
A
Glands of Zeis (sebaceous) and Moll (apocrine).
2
Q
How do the upper eyelid cilia protect the eye?
A
By blocking light and foreign material.
2
Q
What primary function do the adnexa of the eye serve?
A
They maintain a normal physiologic environment for eye health.
3
Q
What is the “gray line” of the eyelid?
A
The visible orifices of the meibomian glands.
4
Q
Which action of the eyelids optimizes light transmission through the cornea?
A
Blinking to distribute tears uniformly across the ocular surface.
4
Q
What role do conjunctival goblet cells play?
A
They produce mucus for tear film stability.
5
Q
What tissue provides structural integrity to the eyelids?
A
The tarsal plate.
5
Q
Which glands are embedded within the tarsal plate?
A
Meibomian glands.
5
Q
What structural component maintains the shape of the eyelids?
A
The tarsal plate.
6
Q
What does the physical action of blinking pump into the nasolacrimal duct?
A
Tears.
7
Q
What are the names of the ligaments that maintain eyelid shape?
A
Lateral and medial palpebral ligaments.
7
Q
Which muscle encircles the eye and allows for eyelid closure?
A
Orbicularis oculi muscle.
7
Q
What is the primary nerve providing motor innervation to the eyelid musculature?
A
Facial nerve (CN VII).
8
Q
What nerve provides sensory innervation to the eyelid skin?
A
Trigeminal nerve (CN V).
9
Q
Which branch of CN V innervates the upper eyelid and canthi?
A
The ophthalmic division of CN V.
9
Q
Which nerve innervates the levator palpebrae superioris?
A
Oculomotor nerve (CN III).
10
Q
Which muscle of the eyelid is innervated by the sympathetic nervous system?
A
Müller muscle.
11
Q
Which artery provides the primary blood supply to the eyelids?
A
Angularis oculi artery.
11
Q
Where does the supraorbital nerve emerge from?
A
The supraorbital foramen in the zygomatic process of the frontal bone.
12
Q
Which artery provides accessory blood supply to the eyelids?
A
Rostral deep temporal artery.
13
Q
Through which vein does the major venous drainage of the upper eyelids occur?
A
Rostral deep temporal artery.
14
Q
What is the lymphatic deqinage of the eye?
A
Ipsilateral mandibular and parotid lymph nodes.
14
Which vein and lymph nodes primarily drain the eyelids?
Infratrochlear vein and ipsilateral parotid and mandibular
15
What component of the tear film do meibomian glands contribute?
The outer lipid component.
16
Lower eyelid innervation
Zygomaticofacial branch of the maxillary division of CN V.
17
Where does the lateral palpebral ligament insert?
On the orbicularis oculi muscle.
17
What role do the cilia-associated glands of Zeis and Moll play?
They provide glandular secretions for eye protection.
18
Which component of the tear film is crucial for eye protection?
The aqueous component.
19
Which muscle contraction enhances the asymmetric ellipse of the eyelid aperture?
Levator anguli oculi medialis.
20
Which muscles are necessary to open the eyelids?
Levator palpebrae superioris and malaris muscles.
21
Which arterial branches contribute to blood supply around the eyelids?
Supraorbital, lacrimal, and malar arteries.
22
Which branch of CN V serves the lacrimal caruncle?
Infratrochlear branch of the nasociliary nerve.
23
Which nerve provides motor control via the auriculopalpebral branch?
Facial nerve (CN VII).
23
Where does the medial palpebral ligament lie in relation to the lacrimal sac?
It overlies the lacrimal sac.
24
Where does the lower eyelid's zygomaticofacial nerve emerge?
Ventral orbital rim.
24
Which nerve block can anesthetize the upper eyelid?
Supraorbital nerve block.
25
What provides additional stability to the tear film?
The lipid component from meibomian glands.
25
Figure 57-1. Overview anatomy of the equine ocular adnexa. (A) Equine eye—lateral view. Cilia (eyelashes) are present in the lateral two-thirds of the upper eyelid. Lower eyelid cilia are poorly developed.133 Upper and lower eyelid skin contains tactile vibrissae (white arrows). The palpebral fissures meet at the medial and lateral canthi and the leading edge of the nictitating membrane is visible at the medial canthus. LC, Lateral canthus; MC, medial canthus; NM, nictitating membrane. (B) Equine eye—anterior view. White arrows delineate the position of the tactile vibrissae. (C) Cannulation of the upper and lower nasolacrimal puncta to highlight their location. White arrows identify the puncta. (D) Magnified view of the upper eyelid mucocutaneous junction. Arrows delineate the openings of the Meibomian gland orifices (the “gray line”).
25
Which muscles are involved in closing the eyelids?
Orbicularis oculi and palpebral muscles.
26
Figure 57-5. A squamous cell carcinoma (black arrow) and melanoma (white arrow) affecting the lower palpebrum in a horse with no eyelid pigmentation. (Courtesy D Knottenbelt, University of Liverpool, United Kingdom.)
26
27
Figure 57-4. An overview of motor and sensory nerve block sites. (A) Distribution of the sensory innervation of the periocular skin of the horse. (B) The sites for sensory nerve blockade (numbers) and upper eyelid akinesia. AP, Auriculopalpebral nerve blockade.
(C) The same sites superimposed onto the equine skull. AP, auriculopalpebral nerve block: Motor to upper eyelid; 1, supraorbital nerve: Sensory central upper eyelid; 2, infratrochlear nerve: Sensory medial canthus; 3, Lacrimal nerve (line block): Sensory lateral eyelid; 4, zygomatic nerve (line block): Sensory lower eyelid.
27
28
Figure 57-6. Photodynamic therapy for squamous cell carcinoma. (A) A photosensitive dye (verteporfin) is injected into the tissue at the base of the debulked tumor bed. A laser with wavelength of approximately 690 nm is used to activate the locally administered dye and destroy remaining tumor cells by necrosis (B). The goal is to irradiate to 200 mW/cm2 as previously described.
28
Why is a systematic approach to diagnosis important in eyelid trauma cases?
To ensure any intraocular disease is detected, which may influence treatment choices.
29
Figure 57-7. Recommended surgical instruments for eyelid surgery. 1, Backhaus towel clamps (4); 2, mosquito hemostats (4); 3, suture scissors; 4, Mayo scissors; 5, Metzenbaum scissors; 6, Stevens tenotomy scissors; 7, Derf needle holder, 8, Castroviejo needle holder; 9, Bard-Parker scalpel handle; 10, Beaver scalpel handle; 11, Cilia forceps; 12, Bishop-Harmon forceps; 13, Brown-Adson forceps (2); 14, Jaeger lid plate; 15, Calipers (Jameson); 16, Irrigation cannula; 17, Bard-Parker blade (no.15); 18, Beaver blade (no. 64); 19, Desmarres chalazion clamp; 20, Eyelid speculum (Guyton-Park).
30
What is the significance of evaluating the angle of upper eyelid cilia during an exam?
It can indicate subtle discomfort, as the angle becomes more acute in blepharospasm.
31
How is Horner’s syndrome identified in horses?
By the presence of ptosis and sweating; enophthalmos and third eyelid protrusion are also possible but less consistent.
32
What tools are recommended for a detailed ophthalmic examination?
Focal illumination, magnification, a Finhoff transilluminator, magnifying loupes, a direct ophthalmoscope, or a slit-lamp biomicroscope.
33
Why might standing sedation be preferred over general anesthesia in some cases?
It allows restraint for minor procedures and reduces the risk associated with full anesthesia.
34
Which sedatives are commonly used for standing restraint in horses?
Detomidine hydrochloride and xylazine hydrochloride.
34
What cardiovascular precaution is recommended before sedation?
Thoracic auscultation, due to cardiovascular suppression risk from sedatives.
35
What is the effect duration of xylazine?
30 to 40 minutes.
36
Why is mepivacaine not recommended for corneal anesthesia?
It does not achieve full corneal anesthesia.
36
What is the primary advantage of combining detomidine with butorphanol?
It provides deeper sedation with minimal cardiopulmonary depression.
36
What is the maximal effect duration of bupivacaine when applied topically?
60 minutes.
37
How long does the effect of lidocaine last?
1 to 2 hours.
37
What is the supraorbital block used for?
To anesthetize the central portion of the upper eyelid.
37
What advantage does regional nerve block provide in ophthalmic procedures?
It facilitates motor akinesia and sensory analgesia.
38
Which nerve’s blockade is essential for upper eyelid akinesia?
The auriculopalpebral nerve.
39
Which imaging technique is preferred for investigating possible orbital fractures?
Radiography, CT, or MRI.
39
What might indicate a need for fine needle aspiration or biopsy in eyelid examination?
Suspicious masses or erosions that may indicate neoplasia.
40
Which periocular tumor type is associated with a poorer prognosis when affecting the eyelid?
Squamous cell carcinoma (SCC).
41
Which horse breeds show a predilection for SCC?
Draft breeds, Appaloosas, and Paints.
41
What adjunctive therapies are recommended for treating SCC?
Photodynamic therapy, chemotherapy with cisplatin, and cryotherapy.
41
What is the recurrence rate of SCC with surgical excision alone?
68.2%.
42
How does tattooing potentially benefit horses prone to SCC?
It may protect against solar radiation damage.
42
What environmental factor increases the risk of SCC?
Ultraviolet (UV) light exposure.
43
How do sarcoids differ from other eyelid neoplasms?
They are benign but locally invasive fibroblastic tumors that recur frequently.
44
Which breeds are at higher risk of developing sarcoids?
Quarter Horses, Appaloosas, Arabians, and Thoroughbreds.
45
What are common clinical signs of periocular sarcoids?
Eyelid swelling, ocular irritation, and possible corneal abrasion.
45
What viral infection is associated with sarcoid development?
Bovine papillomavirus.
46
What approach may be reasonable for young Franches-Montagnes horses with sarcoids?
A “wait and see” approach due to high rates of spontaneous regression.
47
What is the most common adjunctive therapy for sarcoids?
Intralesional chemotherapy with cisplatin.
48
Why is brachytherapy for sarcoids limited in clinical practice?
Due to equipment availability, cost, and radiation exposure risks.
49
What diagnostic procedure is suggested for suspected infectious eyelid diseases?
Impression smears, exfoliative cytology, or culture with sensitivity testing.
49
What is the importance of color Doppler ultrasound in eyelid swellings?
It assesses blood flow and aids in diagnosing venous malformations or dacryoadenitis.
49
What is recommended before adjunctive therapy for sarcoids?
Surgical debulking to reduce tumor size.
50
How can fine needle aspiration help in neoplasia diagnosis?
It helps determine the cell type for accurate diagnosis and treatment planning.
50
What is the prognosis for SCC located on the eyelid vs. the nictitating membrane?
Eyelid SCC has a poorer prognosis for recurrence.
51
What SCC metastasis rate to local lymph nodes has been reported?
Between 6% and 10.2%.
51
What additional therapy is often advised after SCC resection?
Adjunctive therapies like photodynamic therapy or cryotherapy.
52
Why is tear production monitoring important after anesthesia?
Local anesthetics impair tear production, necessitating lubricants.
53
What adjunctive treatment is used in electrochemotherapy for sarcoids?
Cisplatin.
54
Which diagnostic tool aids in distinguishing sarcoids from connective tissue tumors?
Histopathology.
55
What is a critical consideration when sedating animals with suspected severe head trauma?
Avoiding iatrogenic cerebral edema.
56
Why should anesthetic recovery be as smooth as possible in eyelid trauma cases?
To prevent damage to surgical sites, padded helmets may be used for added protection.
56
How might paranasal sinus trauma complicate anesthesia?
It may cause airway inflammation or hemorrhage, increasing anesthetic complications.
57
What type of needles are recommended for most eyelid procedures?
Reverse cutting needles.
58
What solution is applied to the cornea during surgery?
Balanced salt solution to prevent desiccation.
58
Why is cautery beneficial during eyelid surgery?
To manage bleeding due to high vascularity of eyelids.
58
Why are systemic anti-inflammatory drugs used post-trauma or surgery?
To manage inflammation of adnexal structures.
58
What suture material is recommended near the cornea?
Nylon monofilament should be used cautiously to avoid abrasions.
59
What should be used if eyelid function is compromised post-surgery?
Artificial tear ointment to prevent corneal desiccation.
59
What should be confirmed regarding tetanus in trauma cases?
The animal’s vaccination status.
59
What factors influence antibiotic selection post-eyelid trauma?
Hospitalization status, demeanor, and cytological/culture results.
60
Why is gastroprotectant use advised with NSAIDs?
To prevent gastrointestinal damage, especially in dehydrated patients.
60
What is the maximum dosage duration for flunixin meglumine and why?
24–48 hours at 1.1 mg/kg, then reduced to avoid renal/gastrointestinal damage.
61
In what position is a horse placed for adnexal procedures?
Lateral recumbency with the nose elevated.
62
What is a primary indication for temporary tarsorrhaphy?
To protect the cornea in cases of impaired blinking.
63
What precaution is taken to prevent eyelid eversion or inversion in tarsorrhaphy?
Sutures emerge at the meibomian gland orifices.
64
What are stents used for in temporary tarsorrhaphy?
To prevent sutures from tearing through the eyelid.
65
When might a partial permanent tarsorrhaphy be indicated?
In prolonged facial nerve paralysis.
66
How is tarsorrhaphy reversed if no longer required?
The apposition site is incised to restore normal palpebral fissure.
67
What is entropion, and is it common in horses?
Inward turning of the eyelid; relatively uncommon in horses.
68
What are the main causes of acquired entropion in horses?
Trauma, scarring, dehydration, or prolonged blepharospasm.
69
How might mild entropion be managed in foals?
With topical lubricants to protect the cornea.
70
What surgical approach is taken if entropion is persistent?
Eversion with temporary sutures or permanent surgical correction (MODIFIED HOTZ-CELSUS PROCEDURE)
70
How long do eversing sutures usually remain in place?
2 to 4 weeks.
71
What is the main goal when placing eversing sutures?
To correct eyelid position without causing corneal irritation.
72
What is the risk of performing permanent correction surgery in foals too early?
Overcorrection may occur as they grow.
73
What is a critical factor in planning permanent entropion correction?
Eliminating spastic entropion caused by pain to determine the true extent.
73
What instrument is used to support the eyelid during this procedure?
Jaeger lid plate.
74
How does the placement of the elliptical incision affect entropion correction?
The distance between incisions determines the correction extent.
75
What suture orientation is recommended for corneal safety?
Sutures should be oriented radially away from the cornea.
76
What complication can occur if too much tissue is removed?
Ectropion, causing exposure keratitis.
77
How long does eyelid swelling typically last post-surgery?
Around two weeks.
78
What is ectropion, and what are its primary risks?
Outward turning of the eyelid, leading to corneal desiccation and poor tear distribution.
79
What is a common cause of ectropion in horses?
Scar formation from trauma or prior surgery.
80
Describe the V-to-Y plasty technique for ectropion correction.
A “V” incision is made, scar tissue is removed, and the incision is closed in a “Y” pattern.
81
How does the modified Kuhnt-Szymanowski procedure address ectropion?
By removing scar tissue and rotating a skin flap to support eyelid positioning.
82
What is a procedural disadvantage of the Kuhnt-Szymanowski technique?
Increased duration and precision required for cosmetic alignment of skin flap.
83
What is an aesthetic advantage of the Kuhnt-Szymanowski technique?
The scar is hidden among lateral canthus wrinkles.
84
What are distichia in horses?
Aberrant eyelid cilia emerging from the eyelid margin, usually from meibomian gland orifices.
85
Which horse breed is predisposed to distichia?
Friesian breed.
86
What are potential complications of untreated distichia?
Corneal trauma and ulceration.
87
How can distichia cilia follicles be destroyed?
Using electroepilation or cryotherapy.
88
Where is a cryotherapy probe placed for treating distichia?
On the palpebral conjunctival surface, 3–4 mm from the eyelid margin.
89
What is the purpose of the freeze-thaw cycles in cryotherapy for distichia?
To maximize destruction of the cilia follicles.
90
Why might repeated surgeries be necessary for distichia treatment?
Because cilia too short to be visualized cannot be treated initially.
91
What is an ectopic cilia?
Eyelid cilia that emerge through the palpebral conjunctiva, causing corneal irritation.
91
What other treatments exist for distichia besides electroepilation and cryotherapy?
Partial tarsal plate excision or wedge excision.
92
Where are ectopic cilia more likely to occur?
In the upper eyelid, between the 10 and 2 o’clock positions.
93
What is the preferred treatment for ectopic cilia?
Surgical excision.
94
Why are eyelid injuries common in horses?
Due to the wide-set eyes and potential hazards in their environment.
95
How can eyelid trauma lead to swelling in horses?
The eyelids are highly vascular, leading to bleeding and edema post-injury.
96
What imaging techniques might be used for suspected fractures with eyelid lacerations?
Radiography, MRI, or CT.
97
How should eyelid lacerations be cleaned before closure?
Flushed with a 1:50 dilution of 10% povidone-iodine solution, then with sterile saline.
98
What is the preferred suture pattern for palpebral conjunctiva in laceration repair?
Simple interrupted or simple continuous suture pattern.
99
Why should infected eyelid lacerations use nonabsorbable suture material?
To reduce infection risk; these sutures can be removed after 10–14 days.
100
What suture pattern is used to prevent corneal abrasion from suture tags?
Figure-of-eight suture pattern.
101
What postoperative care is recommended after eyelid surgery?
Protective eye mask or fly mask until healing is complete.
102
What type of reconstructive surgery is often required for extensive eyelid lacerations?
Blepharoplasty techniques.
103
Describe the sliding skin flap technique for blepharoplasty.
Skin incisions are made and a flap is advanced to cover the eyelid defect, sutured to the conjunctiva.
104
What is the purpose of Burow triangles in sliding skin flap surgery?
To prevent dog ears and help distribute tension.
105
When is a conjunctival advancement flap used?
For neoplasia or trauma with extensive conjunctival involvement.
106
What is a full-thickness eyelid graft and when is it used?
A graft from the opposite eyelid used when a large defect cannot be closed by a sliding flap.
107
What is a rhomboid graft flap?
A rotated rhombus-shaped flap used to cover large periocular defects.
107
How should a graft be positioned in a full-thickness eyelid graft procedure?
Tarsoconjunctival portion to conjunctival defect, skin portion to skin defect.
108
Describe the sliding Z flap technique.
Triangular skin excisions allow the skin to be advanced over the defect, with suture for eyelid margin creation.
109
What structure in the horse’s eye is known as the third eyelid?
The nictitating membrane.
109
What is the primary structural support of the third eyelid?
A T-shaped cartilage.
110
What is the role of the third eyelid in horses?
Provides protection, tear production, and immunologic defense.
111
Which anesthetic method is often used for third eyelid procedures?
Standing sedation with a sensory infratrochlear nerve block.
111
What diagnostic techniques are used to examine the third eyelid?
Retropulsion, forceps retraction, and palpation of lymph nodes.
111
How does sympathetic tone affect the third eyelid?
Loss of tone causes protrusion, as seen in Horner syndrome.
111
What are the indications for a third eyelid flap?
Corneal bullae tamponade, corneal support, and reducing contamination or tear film loss.
112
Why are third eyelid flaps contraindicated for deep ulceration?
They prevent medication penetration and trap inflammatory cells.
112
What suture pattern is used to secure the third eyelid flap?
Single suture from upper eyelid skin through the conjunctival fornix to the third eyelid.
113
What complications may arise from third eyelid flap sutures?
Skin ulceration and corneal abrasion.
114
What is the purpose of using stents in third eyelid flap surgery?
To prevent skin ulceration from sutures.
114
How can the third eyelid be examined if a foreign body is suspected?
Using retropulsion and forceps for deeper inspection of the conjunctival fornices.
115
What is the most common type of neoplasia found on the third eyelid?
Squamous cell carcinoma (SCC).
115
Describe the typical progression of squamous cell carcinoma on the third eyelid.
It begins as hyperemia, then becomes raised, and may develop a papillomatous appearance.
115
What is the role of the malar artery in the third eyelid?
It supplies vascularization to the third eyelid.
115
Which types of tumors other than SCC are mentioned as affecting the third eyelid?
Hemangiomas, hemangiosarcomas, lymphangiosarcomas, adenocarcinomas, basal cell tumors, and lymphosarcomas.
116
What type of ocular discharge is commonly associated with hemangiomas and hemangiosarcomas?
Hemorrhagic ocular discharge.
116
Why should all masses removed from the third eyelid be submitted for histopathology?
To determine the tumor type and assess surgical margins.
116
What is the reported success rate of surgical excision alone for third eyelid neoplasms?
Approximately 80 to 90%.
117
Name two adjunctive therapies that have been used with third eyelid excision to reduce recurrence.
Gamma- or beta-irradiation, and topical chemotherapeutics such as Mitomycin C and 5-Fluorouracil.
118
What concentration and administration schedule of Mitomycin C has been shown to be effective without excision?
0.2 mL of 0.04% Mitomycin C every 6 hours in cycles of 1 week on and 1 week off for two to three cycles.
119
Under what conditions should a retrobulbar block be used for third eyelid excision?
If additional analgesia is required beyond local anesthesia.
119
Why is cryotherapy discouraged for third eyelid squamous cell carcinoma?
It increases the risk of local tumor recurrence by 2.5 times.
120
Describe the function of the Allis tissue forceps in third eyelid excision.
They are used to grasp and elevate the third eyelid’s T-cartilage.
121
What type of suture material and pattern is recommended for closing conjunctival cut edges?
5-0 to 6-0 polyglactin 910 in a simple continuous pattern.
121
How long should hemostatic forceps be left in place after excision?
1 to 2 minutes.
122
What role does systemic flunixin meglumine play post-surgery?
It reduces inflammation and discomfort.
123
How long is topical antibiotic ointment recommended post-operatively?
5 to 7 days.
123
Why are long-term lubricants generally not required after nictitans gland removal?
Very few equine eyes develop tear production deficits.
124
What two lacrimal glands contribute to the aqueous layer of the tear film in horses?
The lacrimal gland and the gland of the third eyelid.
125
What is the primary function of the tear film?
It maintains corneal lubrication, nutrient supply, immune protection, and a refractive surface.
126
How often is the tear volume in a normal equine eye recycled?
Approximately every 7 minutes.
127
Where is the lacrimal sac located in horses?
In the lacrimal fossa of the lacrimal bone.
128
What is the approximate length of the nasolacrimal duct in horses?
29 to 33 cm.
129
Where does the nasolacrimal duct exit in horses?
Near the mucocutaneous junction in the ventral nasal meatus.
130
Which nerve paralysis is commonly associated with neurogenic keratoconjunctivitis sicca in horses?
Facial and/or trigeminal nerve paralysis.
131
What Schirmer tear test value is considered abnormal in horses?
Less than 10 mm/min.
132
What is the simplest method to assess nasolacrimal duct patency?
Passive drainage of fluorescein to the nasal ostium.
133
What is the preferred type of catheter for nasolacrimal duct cannulation?
A 5 to 6 French gauge pliable urinary catheter.
134
Describe the technique for dacryocystorhinography in the standing horse.
Cannulate the upper lacrimal punctum, inject viscous contrast medium, and then take radiographs.
135
What is the advantage of performing dacryocystorhinography on both nasolacrimal ducts?
It provides an internal control, especially in unilateral disease.
136
What imaging technique has been shown to be effective in evaluating the nasolacrimal duct?
CT dacryocystorhinography.
137
How is endoscopy used in relation to the nasolacrimal duct?
It allows for sample collection in dacryocystitis or the removal of foreign bodies.
138
Why is proparacaine applied directly to the nasolacrimal puncta?
For additional analgesia during cannulation.
139
What surgical instrument is effective for placing a silicone stent in cases of nasolacrimal canaliculus laceration?
A round-tipped, eyed pigtail probe.
139
What staining techniques are used for corneal surface abnormalities?
Fluorescein staining and Rose Bengal staining.
140
What is the purpose of suturing conjunctival cut edges after excision?
To reduce the risk of orbital fat prolapse.
140
How does tropicamide application affect Schirmer tear test results?
It can lower Schirmer tear test values.
141
Which nerve blocks are used for analgesia in third eyelid surgery?
Auriculopalpebral, infratrochlear, and zygomatic nerve blocks.
142
What condition should be considered if a horse has a tear production deficiency following third eyelid excision?
Dry eye or keratoconjunctivitis sicca.
142
What is dacryocystitis?
Inflammation or infection of the nasolacrimal duct or sac.
143
What are dacryoliths, and how can they be managed?
They are tear duct stones that can be diagnosed and removed via endoscopy.
144
Figure 57-8. Temporary tarsorrhaphy. (A) Sutures should be preplaced to distribute tension. (B) Sutures should be placed at partial thickness, crossing the eyelid margin at the level of the meibomian gland openings. (C) Sutures are tied. The use of stents reduces the risk of sutures cutting into the eyelids.
145
Figure 57-9. Permanent tarsorrhaphy. (A) Opposing areas of eyelid margin (approximately 3 mm long) are excised with a No. 11 Bard-Parker scalpel blade. (B) Sutures are placed in the areas of excised margin. Sutures should be left in place for 3 weeks to allow eyelid adhesion.
146
Figure 57-11. Modified Hotz-Celsus procedure for entropion repair. (A) The initial incisions of the skin and orbicularis oculi muscle are made with a scalpel. (B) The skin and superficial orbicularis oculi muscle are excised with scissors. (C) A single-layer closure, starting at the center, incorporates both skin and orbicularis oculi muscle. (D) Postoperative appearance.
147
Figure 57-13. Repair of eyelid laceration. (A) Minimal débridement is performed. (B) Closure is performed in two layers, starting at the eyelid margin to ensure optimal alignment. (C) and (D) Skin closure is accomplished with simple interrupted sutures (4-0 or 5-0). A figure-of-eight suture pattern is useful for closure of the eyelid margin, as it allows suture placement on the eyelid margin, with placement of the knot away from the globe.
148
149
Figure 57-15. (A) Example of an eyelid laceration before repair in a horse; (B) A two-layer closure was performed in the upper palpebral conjunctiva and palpebral skin using absorbable suture material. Wound dehiscence is a risk because of extensive vascular injury.
150
Figure 57-16. Sliding skin flap to repair eyelid defects. (A) Proportions of incisions should be ab=b=cd=de. (B) Equilateral triangles of skin are excised, as is the affected portion of eyelid. The skin flap and adjacent skin are undermined with scissors. Adjacent conjunctiva is mobilized and closed with absorbable suture (polyglactin 910 [6-0 Vicryl]). (C) The skin flap is advanced, and the leading edge of the flap is sutured to the conjunctiva and skin.
151
Figure 57-17. Tarsoconjunctival advancement flap. (A) A skin advancement flap is prepared as in Figure 57-16. (B) Conjunctiva of the upper eyelid opposite the defect is incised 3 to 4 mm from the eyelid margin and is undermined to create a flap. (C) The conjunctival flap is advanced and sutured into the defect.
(D) The skin flap is advanced and sutured in place. (E), A temporary tarsorrhaphy relieves tension on the flaps. The use of stents helps to distribute tension. (F) After 4 weeks, the tarsorrhaphy is removed and the conjunctival flap is severed at the level of the eyelid margin. The conjunctiva and skin are apposed with a continuous pattern of 6-0 or 7-0 absorbable suture.
152
Figure 57-18. Full-thickness eyelid graft. (A) The area of affected lower eyelid is excised. (B) The upper eyelid is excised 5 mm above the eyelid margin opposite the defect. (C) The graft is split into skin and tarsoconjunctival layers. The graft is advanced under the eyelid margin and sutured in place. (D) The bridging eyelid margin is sutured to the graft. A temporary tarsorrhaphy alleviates tension on the graft. (E) After adequate healing has occurred, the graft is severed along the intended eyelid margin. (F) The conjunctiva and skin are apposed along the eyelid margin with a continuous suture pattern. The skin flap is sutured to the bridge to complete the closure.
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Figure 57-19. Rhomboid graft flap. (A) The rhomboid is aligned with one side along the position of the eyelid margin. Sides of the rhomboid are equal. The replacement flap is incised on a line (A1) continuous with the diagonal of the rhomboid, for a distance equal to the sides of the rhomboid. The second incision (A2) is also equal in length, and is placed parallel to the side of the rhomboid. (B) The lesion is excised and conjunctiva is mobilized to cover the replacement flap. (C) The flap is dissected free from underlying tissue and rotated into position. (D) The flap is sutured in position with the leading edge forming the new eyelid margin. (Angles 1 and 2 are indicated on B and D to aid in orientation.)
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Figure 57-20. Sliding Z flap. (A) Growths of the lateral eyelid can be removed en bloc. The triangular areas of skin to be removed adjacent to the defect are marked. Excision of these flaps facilitates skin mobilization. (The bases of the triangles align with the diagonal of the defect.) (B) Adjacent skin is undermined. (C) Equivalent triangles of skin are excised. (Cut edges A, A′, B, and B′ are shown to aid in orientation for advancement of the flap.) (D) The flap is advanced and sutured in place.
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Figure 57-23. Surgical removal of the third eyelid. (A) Local anesthetic is injected at the base of the third eyelid. (B) The nictitating membrane is lifted from the fornix with forceps. (C) Two hemostats are placed across the base of the third eyelid. (D) The third eyelid is excised along the two hemostatic forceps.
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Figure 57-24. Methyl methacrylate cast of the left nasolacrimal duct of a horse. The medial bony orbit and medial wall of the lacrimal canal have been removed. A, Lacrimal sac; B, course of the duct within the lacrimal bone; C, narrowing of duct lumen before exiting lacrimal bone; D, exit of duct from lacrimal bone; E, compression of duct by cartilage within alar fold; F, cast within the basal fold. (Courtesy Latimer CA, Wyman M, Diesem CD, et al. Radiographic and gross anatomy of the nasolacrimal duct of the horse.
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Figure 57-25. Identification and catheterization of the nasal ostium. (A) The nasal ostium is visible in the ventral nasal meatus close to the mucocutaneous junction (white arrow). (B) Distal catheterization using a 5 FG rubber urinary catheter facilitates retrograde flushing of the nasolacrimal system.
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Figure 57-26. Normal right lateral equine dacryocystorhinogram illustrating the anatomical features shown in Figure 57-23. A, Lacrimal sac;
B, course of the duct within the lacrimal bone; C, mild narrowing of duct lumen before exiting lacrimal bone; D, exit of duct from lacrimal bone; E, compression of duct by cartilage within alar fold. (
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Figure 57-27. Transverse computed tomography dacryocystography scan of an equine skull at the level of the caudal maxillary sinus. There is a fracture of the left maxilla with adjacent soft tissue swelling (arrowhead). No disruption of the nasolacrimal duct is evident (arrow). The inset is a close-up of the nasolacrimal canal and duct. (Courtesy Nykamp SG, Scrivani PV, Pease AP. Computed tomography dacryocystography evaluation of the nasolacrimal apparatus. Vet Radiol Ultrasound. 2004;45:23.)
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Figure 57-28. A catheter is sutured to the periorbital skin (A), and skin of the nostril (B) after cannulating and surgical opening of an imperforate nasolacrimal duct.
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Figure 57-29. Repair of the severed lacrimal canaliculus. (A) Laceration of the lower eyelid, severing the lacrimal canaliculus. (B) A 2-0 to 4-0 nylon or polypropylene suture is passed through the nasolacrimal duct and exits through the wound. A Worst probe is passed through the ventral punctum and draws the suture through the distal portion of
the severed canaliculus. (C) A fine silicone tube is cut to a taper, tied to the suture, and pulled through the canaliculi. (D) The canaliculus and wound are sutured with 6-0 nylon silk. (E) The tubing is sutured to the skin of the eyelid and at the nasal end. It is left in place for 3 weeks.
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