Canthal resection is a surgical procedure where part of the canthus is cut out to treat eyelid malpositions and preserve vision. The canthus is the outer or inner corner of the eye or the angle at the upper and lower eyelid’s junction. Lower eyelid malpositions can be congenital or due to acquired reasons. Several procedures to correct various types of eyelid malpositions include lateral canthal surgical techniques, medial canthus resection, transcaruncular medial canthal ligament (MCL) plication, and others.
Eyelid malpositions are often caused by MCL laxity, giving rise to symptoms like blurred vision, watery eyes, feeling of a foreign body, superficial punctate keratopathy (caused by the death of small groups of cells), and discomfort. MCL may be due to infiltrations of fat into the ligament, involutional attenuation (shrinkage/reduction), and persistent traction (caused by paralytic or cicatricial (scar-related) lower eyelid and midfacial retraction).
Preparation & Expectation Before Surgery
The patient will be taken through a routine, full ocular examination. The doctor assesses the lid's position and the functioning capabilities of the lacrimal damage apparatus. S/he also checks for lid, medial, and lateral laxity. Local or general anesthesia is used in the surgery. The doctor will also discuss the risks and benefits involved. The patient is expected to adhere to the standard preoperative requirements such as not eating, drinking, taking alcohol, or smoking cigarettes several hours or days before the procedure.
Types, Purpose & Procedure
Canthal resection serves many purposes, depending on the type. For example, medial canthus resection:
- Shortens the medial canthal tendon directly.
- Postero-fixates medial canthal tendon to the posterior lacrimal crest (the ridge that divides the lacrimal bone’s orbital surface).
- Maintains lacrimal patency (lacrimal is unobstructed) when the cut inferior canaliculus (small passageway) undergoes marsupialization (cutting and suturing slit edges).
Canthal resection is performed in the event of medial canthus lacrimal laxity. The medial canthus ligament consists of three limbs and other structures that help the lower eyelid to maintain its height and contour. It also helps with proper apposition (side by side position) of the lower eyelid to the globe and supports the lacrimal pump's function. Medial canthus lacrimal laxity can affect each of the above functions, hence the need for surgery.
Transcaruncular MCL plication is minimally invasive and is used to restore eyelid support that is usually given by the tripartite ligament (three limbs). It effectively treats MCL laxity, which often plays a role in lower eyelid malposition.
The surgical procedure involving medial ectropion surgery may be complicated if there is medial canthal tendon laxity. It becomes challenging to recreate the posterior attachment since the tendon has a deep and superficial head. It is possible to interfere with lacrimal drainage and fail to improve the eyes' excessive watering because the medial canthal tendon is not sufficiently shortened. Therefore, the medial canthal structures can undergo resection with a horizontal lid shortening. Next, the surgeon reconstitutes the medial canthal tendon's posterior limb using a permanent suture. He also performs marsupialization of the cut inferior canaliculus into the lower fornix’s conjunctival sac.
In medial canthal tendon, the surgeon grasps the lower lid margin close to the punctum (tip) and pulls it laterally. The surgeon cuts vertically through its full thickness, including the inferior canaliculus and medial canthal tendon. He/she deliberately preserves as much canaliculus as possible since it will later be used for marsupialization. Further procedures will see the lid shortened with both ends of nonabsorbable suture placed through the upper and lower parts of the cut tarsal plate. A new ostium (opening or cavity) is fashioned, and the lid margin held medially as the surgeon permanently ties the suture to approximate the medial canthal angle.
Lateral canthal surgical procedures are performed to preserve vision and manage existing lower eyelid malpositions. These procedures are employed during blepharoplasty (droopy eyelid repair) to prevent lower eyelid malpositions.
Risks, Side Effects & Complications
Canthal resection is generally a safe and effective surgical treatment with minimal complications, risks, and side effects. There may be postoperative swelling in the caruncle and semilunar fold areas. Sometimes a wound may form, and postoperative ocular surface irritation may arise.
Complications include breakage of sutures, pyogenic granuloma (abnormal increase in blood capillary vessels), and kinking (sharp twisting) of the lower eyelid margin.
After Care, Recovery & Results
After surgery, the surgeon pads the eye for 48 hours to lessen postoperative swelling. S/he also removes skin sutures five days after surgery while the lid margin suture is removed after ten days.
Canthal resection effectively cures problems such as medial ectropion accompanied by tendon laxity. It usually registers positive outcomes in shortening the medial canthal tendon while the patient’s lacrimal drainage system is effectively re-established.
Transcaruncular surgical technique for MCL plication has demonstrated effective or positive outcomes, whether used alone or in conjunction with other techniques. The procedure has also registered success in meeting the cosmetic and functional needs of patients who have medial ligament laxity, the severity notwithstanding.
Canthal resection involving the medial canthal tendon laxity may have poor outcomes in lid-globe apposition because of the directed pull on the lid anteriorly.