Rudolph S. Wagner, MD
Ophthalmologists frequently encounter disorders of the lacrimal system, particularly in infants and young children. Epiphora in the first year of life has been reported to occur in as many as 20% of children.1 Knowledge of the developmental anatomy, congenital anomalies, and other abnormalities of the nasolacrimal system is essential for management of the clinical conditions encountered. In this tutorial, problems in tear production and drainage are discussed and some controversial management issues are presented. Endoscopic management of congenital mucoceles is also discussed.
Normal tears provide oxygen and nutrients to the corneal epithelium. They also provide hydration and create a smooth refracting surface. The immunoglobulins and lysozymes in tears serve a bactericidal function.2 There are three components or layers of the precorneal tear film. The inner mucin layer, produced by conjunctival goblet cells, allows aqueous tear fluid to adhere to the hydrophilic epithelium. The accessory lacrimal glands primarily contribute to the middle aqueous layer. The accessory lacrimal glands include the glands of Krause and Wolfring located at the upper and lower conjunctival fornices. The third layer is the superficial oily layer that slows the evaporation of tears. Meibomian glands, sebaceous glands of Zeis, and apocrine glands of Moll lie along the lid margins and produce this outermost layer.
The main lacrimal gland is responsible for reflex and psychogenic tearing. It is located in a shallow depression within the orbital portion of the frontal bone. The lateral horn of the levator aponeurosis divides the gland into orbital and palpebral lobes. The smaller palpebral portion can often be seen in the superolateral conjunctival fornix when the upper lid is everted. Thin-walled ducts pass down into the superior conjunctival fornix and open approximately 5 mm above the edge of the tarsus, delivering the aqueous tears. A tear lake is formed along the lid margins.3
Reflex tearing begins shortly after birth, but may be delayed for several weeks. Psychogenic tearing typically begins between 2 and 4 months of age.4
Alacrima (congenital absence), or marked deficiency of tear production, has been reported in association with aplasia of the lacrimal gland5 or brainstem nuclei that control lacrimation, or with ectodermal aplasia.6,7 Alacrima can also occur as an idiopathic condition in otherwise healthy individuals.8 Clinical manifestations of alacrima may include chronic ocular irritation and photophobia, a viscous tear film, and punctate corneal epithelial erosions. In cases of aplasia of the main lacrimal gland, ocular signs and symptoms are minimal because baseline tear production is unaffected.
The Riley-Day syndrome, or familial dysautonomia, is a generalized disorder of autonomic and sensory nerve function. It occurs almost exclusively in families of Ashkenazic Jewish descent, and is inherited in an autosomal recessive pattern.9 Systemic signs include dehydration, hyporeflexia, and insensitivity to pain. Altered parasympathetic innervation of the lacrimal gland may interfere with tear production. Corneal hypesthesia or anesthesia may contribute to their problems with exposure keratitis. Management includes liberal use of viscous artificial tears and lubricating ointments. Punctal occlusion and partial tarsorrhaphy may be required in some cases.10
Anatomy of the Lacrimal System
The lacrimal drainage system forms from a depression of ectodermal cells within the nasolacrimal groove. A solid core of ectoderm extends from the eyelids to the nose. Canalization of this solid cord begins at approximately 3½ months’ gestation. This process is usually completed at or near the time of birth, with the lower portion of the system being the last to canalize. The valves seen in the mature system represent areas of incomplete disintegration of the ectodermal cells. Anomalies may occur anywhere along the course of the system.11,12
|
The lacrimal sac lies within the lacrimal fossa, between the anterior and posterior crura of the medial canthal tendon. Unlike the canaliculi, which are lined with stratified squamous epithelium, the lacrimal sac is lined with a pseudostratified columnar epithelium with goblet cells. The lacrimal sac is 10 mm to 15 mm in length, with the superior end extending above the canthal tendon.
The nasolacrimal duct (NLD) is approximately 12 mm in length, and extends from the lacrimal sac through an ostium beneath the inferior nasal turbinate into the lateral portion of the nose. The ostium is partially covered by a mucosal fold called the valve of Hasner, which may remain imperforate.
An active pump mechanism driven by the orbicularis muscles facilitates tear flow. Upon blinking, the superficial and deep heads of the pretarsal orbicularis contract, compressing the ampullae and shortening the canaliculi. Simultaneous contraction of the deep heads of the preseptal orbicularis, which are attached to the sac, creates negative pressure. This negative pressure expands the sac and draws in fluid from the canaliculi. When the eye opens, these muscles relax and the sac collapses, forcing tears through the duct into the nose.13
Punctal Atresia or Agenesis Agenesis of the lacrimal puncta is an uncommon occurrence,14 involving one or more undeveloped puncta. Symptoms will vary depending upon which and how many puncta are involved. With agenesis or atresia of all four puncta or the two lower puncta, epiphora occurs once the child begins producing tears. Patients usually present with a watery discharge because there is no reflux of mucus from the blocked puncta. It is important to look for ectopic puncta along the medial lid margins and medial canthal area, including the semilunar fold. Atresia of the puncta commonly will be found. In these cases, careful inspection under magnification will reveal a thin membrane occluding the punctal opening, preventing the entry of tears into an otherwise normally developed canalicular system. Treatment involves perforating the membrane with a fine needle followed by punctal dilatation with a standard punctum dilator.15 A probing or irrigation should then be performed to demonstrate patency of the distal system. A dacryocystorhinostomy (DCR) may be required in some cases when epiphora is significant.
Lacrimal Sac Fistula
|
Obstruction, or impatency, of the nasolacrimal duct is the most common disorder of the lacrimal system. In published reports, the incidence of epiphora in infants ranges from 1.2% to 6%.18,19 MacEwan and Young observed a cohort of 4792 infants in Scotland to determine the incidence and natural history of nasolacrimal duct obstruction during the first year of life.1 They found evidence of defective lacrimal drainage in 20% of these children at some time during the first year of life.
Dacryostenosis, or atresia, of the nasolacrimal duct is believed to result from failure of canalization of the column of epithelial cells that form the nasolacrimal duct. Adhesions between the ductile epithelium and nasal mucosa may also be responsible for this condition. Areas of obstruction can occur anywhere along the duct where valves are formed. The most common site of obstruction, however, is at the mucosal entrance into the nose (valve of Hasner), under the inferior turbinate.11
Symptoms and Signs Symptoms of congenital nasolacrimal duct obstruction (CNLDO) may be present at birth, but usually manifest at a few weeks of age as tear production matures. In cases in which the blockage does not resolve spontaneously, symptoms increase during the first few months of life as normal tear production increases. The obstruction may be present in one or both eyes, although it is more frequently a unilateral condition. Ophthalmologists are familiar with the signs of CNLDO that include an overflow of tears onto the lower lid and cheek.
|
The clinical diagnosis of this condition is usually based on history and recognition of the signs described in the preceding paragraph. Gentle pressure on the lacrimal sac with the index finger will usually produce a reflux of aqueous or mucoid material through the puncta. The diagnosis can be confirmed with the fluorescein dye disappearance test. A drop of 2% fluorescein solution is placed in the lower conjunctival fornix of each eye. Alternatively, the conjunctiva may be touched with a moistened strip of fluorescein-impregnated filter paper. The excess dye is wiped away from the skin of the lids. The child is observed from a distance of 3 to 4 feet, while illuminating the eye with a cobalt filtered (blue) light from a pen light, slit lamp, or ophthalmoscope. Normal lacrimal system outflow results in clearance of all dye from the tear lake within 5 minutes. Frequently, there is an obvious retention of the dye after 10 minutes when CNLDO is present.
Natural History Numerous studies have shown that observation and medical treatment will lead to resolution of the symptoms of CNLDO in the majority of cases. In 1923, Crigler reported nearly 100% success with a conservative regimen that included digital massage of the lacrimal sac.20 In 1947, Price reported spontaneous resolution of dacryostenosis by 2 years of age in 192 of 203 (94.6%) cases.21 Peterson and Robb observed the natural history of CNLDO in 65 infants and found that 50% were free of symptoms by 4 months of age and 85% by 13 months of age.22 In Paul’s study of 62 patients treated with daily lacrimal massage and topical antibiotic ointment, resolution occurred by 1 year of age in 90% of patients.23 Nelson and associates showed that in 109 of 113 (94.7%) cases of CNLDO, symptoms resolved by 14 months of age on a similar regimen.24 The definitive prospective study of MacEwen and Young had an overall spontaneous resolution rate of 96% at 1 year of age in their cohort of 964 patients.1 It is interesting that in their patients, topical antibiotics and lacrimal massage were not prescribed. Parents were advised to wipe the sticky lids and lashes with cooled, boiled water. It is generally accepted that at 12 through 14 months of age, spontaneous resolution is unlikely to occur and surgical treatment is indicated.
Management Most ophthalmologists agree that conservative management should be undertaken in the first few months of life. Management includes frequent cleansing of the lids and lashes and application of topical antibiotic drops or ointment when there is a mucopurulent discharge. The digital hydrostatic massage originally described by Crigler may be useful.20 This technique involves placing a finger over the lacrimal sac and common canaliculus to block the exit of fluid toward the eye, while firmly stroking downward to increase hydrostatic pressure within the lacrimal sac. The induced pressure may rupture the membranous obstruction of the nasolacrimal duct. Kushner compared treatment with Crigler’s hydrostatic massage, simple massage (gentle pressure over the nasolacrimal system to express fluid from the puncta), and no massage in a series of 132 children with 175 affected eyes.27 In Kushner’s study, 18 of 59 eyes treated with hydrostatic massage improved, versus 5 of 58 eyes in the simple massage group and 4 of 58 eyes in the control group. In MacEwen and Young’s large study, although lacrimal sac massage was never prescribed, they found a 96% resolution rate at 1 year of age.1 Although not established as curative, lacrimal sac massage is useful in clearing the lacrimal sac of accumulating mucoid material even if the obstruction is not overcome. Copious amounts of material may reflux from the puncta with gentle massage and can be easily wiped away by the parents.
I demonstrate to the parents the correct methods of both hydrostatic and gentle massage and advise them to perform this throughout the day as mucoid discharge accumulates. I usually prescribe an ophthalmic antibiotic ointment such as erythromycin, or a topical antibiotic solution such as trimethoprim sulfate and polymyxin B to be applied when there is excessive discharge. I also advise frequent cleansing of the lids and lashes with warm water. Systemic antibiotics have limited usefulness and should be reserved for cases of CNLDO with preseptal cellulitis. Parents are advised about the likelihood of spontaneous resolution of epiphora according to the data of MacEwen and Young (Table).1
Table 1. Guidelines for predicting spontaneous resolution of congenital nasolacrimal duct obstruction. The Table shows the percentage of nfants at each month, who on follow-up, resolved before 1 year of age.1
| Age of Patients Presenting with Nasolacrimal Duct Obstruction | Percent of Cases Resolving Before 1 Year of Age |
|---|---|
| 1 month | 96% |
| 2 months | 93% |
| 3 months | 90% |
| 4 months | 86% |
| 5 months | 82% |
| 6 months | 75% |
| 7 months | 64% |
| 8 months | 49% |
| 9 months | 36% |
| 10 months | 23% |
| 11 months | 5% |
| 12 months | 0% |
Timing of Probing There is no universal agreement regarding the timing of the initial probing for CNLDO. Despite the natural history of the condition in which more than 90% of children will resolve by 1 year of age, some ophthalmologists continue to advocate early surgical probing.25-27 These early probers suggest that prolonged epiphora is annoying to both the parent and the child. They also voice concern that a delay in probing may increase the risk of infections and associated scarring of the system, and may decrease the success rate of initial probing at a later date. Fooks warned that abscess formation in the lacrimal sac may be a consequence of postponing surgical treatment.28 Severe infections such as dacryocystitis are uncommon in children with CNLDO and are usually managed successfully with systemic antibiotics. However, probing may be necessary for definitive management.
In a retrospective study of 427 patients with CNLDO involving 572 eyes, Katowitz and Welsh reported success in 97% of cases when probing was performed prior to 13 months of age.19 After 13 months, however, the success rate was found to decrease with age, 76.4% between 13 and 18 months and 33.3% for patients probed after 24 months. In contrast, when El-Mansoury and associates reviewed the results of 138 initial probings performed between the ages of 13 months and 7 years of age, they found that more than 90% were curative regardless of age.29 Robb reported similar data, reflecting a uniform cure rate of nearly 90% with the first-time probing in children ranging in age from 1 to 9 years old.30 Recently, Kushner has reported that simple probing has an excellent success rate in children up to 4 years of age, if an uncomplicated obstruction is found at the valve of Hasner.31
Others argue that early probing of children younger than 8 months of age can be performed in the office or outpatient clinic with the child alert and minimally restrained. This avoids the risks of general anesthesia and eliminates the costs of hospitalization. However, Kushner points out that the present risks of general anesthesia may not be as significant as in past years because of improvements in administration and monitoring.32 Also, if one considers that up to 70% or more of the early probings performed may not have been necessary because the cases would have resolved spontaneously with time, the cost savings are negated.
In his own series, Kushner probed 175 patients’ nasolacrimal duct obstructions in the office before they reached the age of eight months.27 He reported a success rate of 97%. In a recent editorial, however, he noted that he advises his fellows not to perform office based probings until they have substantial experience with probing in the more controlled setting afforded by general anesthesia.32
Kassoff and Meyer have reported success rates of more than 99% for both early office probing and later hospital probing.33 They experienced few complications with both approaches. Their studies imply that either method can lead to successful results. I strongly agree with Kushner who believes that the complication rate of probings performed in the office at 6 months of age would be substantially higher if all probings were performed as an office procedure without anesthesia or sedation. Many proponents of early probing selectively determine the patients who should be probed in the operating room. To avoid complications such as lacerating the puncta or canaliculus, or creating a false passage with a misdirected probe, I suggest probing all patients under anesthesia in a surgical center or operating room and not in the office. This is particularly important for surgeons who perform this procedure infrequently.
Probing and Irrigation Probing of the nasolacrimal system is performed under general anesthesia ideally in patients 12 to 15 months of age. The procedure may be performed at a younger age if symptoms warrant earlier intervention. A nasal airway or laryngeal mask may be used, or endotracheal intubation may be performed to administer general anesthesia. Preoperative evaluation determines if the puncta are present and in the normal location. Operating loupes should be used for this procedure. The upper punctum is dilated using a punctum dilator. A 0 or 00 Bowman probe is passed vertically through the puncta for a short distance and then directed horizontally and medially. A key maneuver is to apply lateral tension on the lid to straighten the canaliculus while the probe is advanced medially. Failure to do this maneuver will result in a kinking of the canaliculus. The tip of the probe will encounter the medial wall of the lacrimal sac against the lacrimal bone. The probe is then rotated vertically, flat against the face. The first molar is used as a landmark for the direction of the probe as it is advanced along the nasolacrimal duct into the nose.34 Resistance is often met at the lower end of the duct, and is usually overcome with gentle but steady advancement of the probe. Presence of the probe’s tip below the inferior meatus in the nasal cavity can be confirmed by feeling metal on metal contact with a second probe passed through the external nares along the lateral floor of the nose. Patency may be confirmed by irrigating fluorescein dye-saline solution through the system and recovering the dye with a suction catheter in the nose. Some surgeons repeat the probing procedure through the lower punctum.
Failure of the initial probing may require a second procedure in which the probing is repeated. Nasal examination may be performed with inspection of the inferior turbinate.35 If this structure is found to be in a tight approximation against the lateral wall of the nose, it may be contributing to the obstruction. In such cases, the turbinate may be fractured toward the septum (infractor), using the blunt end of a Freer elevator, a straight hemostat, or a large probe.
Balloon Catheter Dilatation Balloon catheter dilatation is an effective primary procedure for the treatment of CNLDO in children older than 12 months of age and is useful after failure of lacrimal duct probing or silicone intubation.36 In this procedure, probing is performed as described above. A lacrimal catheter (e.g., Lacricath, Atrion Medical Products, Birmingham, Alabama) is inserted through the puncta and directed into the nasolacrimal duct. Here it is inflated for 90 seconds and then deflated and removed, according to the recommended protocol. This procedure can be highly effective and is particularly useful in older children. Silicone intubation can be avoided in many cases.37
|
Crawford tubes are now available with a fine silk suture within the lumen of the tube. The silicone can be stripped away and the suture can be tied creating a small knot. This technique has an advantage of removing the tubes by grasping them in the medial canthal area, and cutting and pulling the tube out, which avoids retrieval in the nose. This method is particularly useful in young children and may eliminate the need for a second anesthesia.
Despite the method that is used to secure the tube, care must be taken to adjust the tension of the loop in the medial canthal area. The loop must be tight enough to prevent corneal touch, yet loose enough so as not to slit the canaliculi. Most surgeons prefer to keep the tube in place for 6 to 12 months, although resolution of epiphora has been reported to occur after 6 weeks.39-41
Children whose symptoms do not resolve following silicone intubation may occasionally require DCR. This procedure is considered to be less successful in children than in adults because of facial bone growth and tendencies for excessive scar tissue proliferation in children. Nevertheless, Nowinski and associates reported an overall success rate of 83% in DCR performed on patients younger than 17 years of age, and an 88% success rate in cases of CNLDO.42
This article was supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, NY.
|
|
Recently, congenital lacrimal sac mucoceles associated with respiratory distress have been reported.46 In these cases, an extension of the mucocele from the opening in the inferior meatus was found. A blue-gray intranasal mass is visualized using nasal endoscopy or under direct visualization. Imaging studies are helpful in delineating the extent of the mass (Slide 6).47 Obstruction of the respiratory passages requires intervention. Wagner and Lin have reported on the successful management of five cases of lacrimal sac mucoceles.48 The researchers performed probing with nasal endoscopy
|
|
Because nasal extension may occur more frequently than previously realized, nasal endoscopy should be performed when a probing procedure is performed to treat a congenital lacrimal sac mucocele.
Lacrimal system disorders occur frequently in the pediatric population. Congenital nasolacrimal duct obstruction resolves spontaneously in most cases by 13 months of age. Conservative management includes massage of lacrimal sac and application of topical antibiotic solution or ointment. Probing and irrigation performed under general anesthesia between 12 to 15 months of age provide a cure in most cases. Newborns with lacrimal sac mucoceles may experience respiratory distress from nasal extension of the mucocele. These infants should be managed with probing in conjunction with nasal endoscopy.
