Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology for Primary Care 3rd edition_Wright, Farzavandi_2008

probing. Old literature suggests probing prior to 1 year of age is preferred as probing after 1 year of age has a significantly lower rate of success. More recent literature has shown the success rate of a simple probing is approxi mately 90% for all ages up to 3 years (Macan et al). This author recommends

initial probing between 6 months and 1 year of age if there is recurrent infec tion, but one can safely wait if the tearing is minimal or intermittent. There is one important situation, however, when an early nasolacrimal duct prob ing is indicated even as early as the first week of life, and that is an infected amniotocele (discussed later in this chapter).

Medical Management of Nasolacrimal Duct Obstruction

Medical management during the observational period is a combination of possibly nasolacrimal sac massage and intermittent topical antibiotics. Some suggest massaging while others do not. If massage is used, 2 techniques have been described: (1) push inferiorly to express the tears down and out the nasolacrimal duct; (2) massage superiorly so the material exits the puncta. This author suggests using both methods. The initial massage is directed inferiorly to push the tears in the normal direction out the nasolacrimal duct. Subsequent massage is directed superiorly so that any tears that did not exit are at least cleared from the puncta. Occasionally, inferior pressure itself will open a mild nasolacrimal duct obstruction (this is rare). For the most part massage is optional because it is difficult for parents to perform. The use of topical antibiotic drops or ointments is indicated if there are signs of infection, such as mucopurulent discharge or conjunctival injection. Antibi otic drops work well, but should only be prescribed when there is evidence of a true infection.

Surgical Treatment of Nasolacrimal Duct Obstruction

Nasolacrimal duct probing is the primary procedure of choice for opening a nasolacrimal duct obstruction. It is a simple but delicate procedure that usually takes less than 5 to 10 minutes to perform. A small wire probe (Bow man probe) is passed through the punctum into the nasolacrimal system to break through a tissue membrane at the distal end of the nasolacrimal duct at the Hasner valve. First the punctum is dilated, then the probe is passed through the punctum, along the canaliculus, into the nasolacrimal duct, then through the Hasner valve and into the nose (Figure 12 3). The surgeon

A B

Figure 12 3.

A, Drawing of a nasolacrimal duct probing. First a Bowman probe is passed through a dilated upper punctum through the upper canaliculus and into the nasolacrimal sac. B, The probe is then directed inferiorly to penetrate the membrane that blocks the Hasner valve. This pass of the probe into the nose

punctures the valve and opens the nasolacrimal dict obstruction.

can usually feel a pop as the probe breaks the membrane at the Hasner valve. In some cases the inferior turbinate covers the opening; in these cases the turbinate is infractured to relieve crowding and allow tear drainage. In cases where primary nasolacrimal duct probing fails, reoperation with silicone tube intubation is usually used to keep the nasolacrimal duct open (Figure 12 4). In general, silicone tubes are only used for patients who have failed the probing procedure, but they can be used as a primary procedure. The silicone tubes are usually removed after 4 to 6 weeks. Another procedure is to dilate the duct with a balloon catheter. This is usually reserved for com plex cases or reoperations.

Amniotocele (Congenital dacryocystocele)

An amniotocele presents as a swelling of the nasolacrimal sac at birth. This is caused by an accumulation of fluid within the sac, as a result of punctal and nasolacrimal duct obstruction. At birth it appears as a bluish swelling in the medial canthal area, representing fluid that is sequestered within a distended nasolacrimal sac (Figure 12 5A). This represents an obstruction at the canaliculus and at the Hasner valve with the sac full of fluid. This is distinct from a common nasolacrimal duct obstruction where the nasolac rimal duct is not distended and there is no loculated fluid. Treatment for an amniotocele is immediate local massage. If decompression does not occur within a few days, infection of the nasolacrimal sac (ie, dacryocystitis)

A B

Figure 12 4.

A, Drawing of silicone stent in the canaliculi and nasolacrimal system. The silicone tube has a probe attached to each end and a central suture inside the silicone tube. One probe

is passed through the upper punctum and one probe is passed through the lower punctum so the 2 probes meet in the nose. The probes are cut off the ends of the silicone tube to expose the central suture. B, The suture inside the silicone tube is tied together in the

nose to join the ends of the silicone tube in a loop. The loop of tube is left in place for 1 to 3 months to keep the system open and prevent membrane regrowth.

is almost certain. The author suggests urgent probing of the nasolacrimal duct to open the obstruction if signs of infection are present, such as ery thema or increased swelling. An infected amniotocele is red, warm, and quite large, more than 1 cm in diameter (Figure 12 5B). Prior to probing treat with intravenous antibiotics (cephalosporin) for 1 or 2 doses and then decompress the distended sac by urgent nasolacrimal duct probing. Urgent nasolacrimal duct probing to relieve the obstruction and drain the abscess is almost always required. Cutaneous incision into the nasolacrimal sac to decompress the abscess was once advocated but should be avoided because this does not establish the normal drainage into the nose and results in an external fistula. Antibiotics alone rarely if ever cure an infected amniotocele, and if the abscess is not drained by probing chronic infection occurs, which can lead to regional cellulitis and sepsis (Figure 12 6).

A B

Figure 12 5.

A, Amniotocele right lacrimal sac in 4-day-old newborn. The amniotocele is the bluish cyst just inferior to the medial canthus. The amniotocele is not infected at this time. B, Infected amniotocele right eye at 10 days after birth. Note the redness and swelling in the medial canthal area and upper lid. Urgent nasolacrimal duct probing is indicated.

Congenital Nasolacrimal Duct Fistula

In rare instances, the nasolacrimal duct connects to the skin overlying the base of the nose, causing tears to drain down the cheek (congenital nasolacrimal duct fistula). Often, there is a concurrent nasolacrimal duct obstruction associated with the fistula. A nasolacrimal duct fistula is best treated by closing the fistula surgically, opening the nasolacrimal duct obstruction with nasolacrimal probing, and performing intubation using silicone tubes.

Punctal Atresia

Punctal atresia is lack of the eyelid puncta. If only one punctum of the pair is obstructed, normal tear drainage can still occur through the other punc tum. In cases where punctal atresia is causing tearing, surgical intervention is indicated to create a new punctal opening.

Congenital Glaucoma

Tearing is one of the most common presenting signs of congenital glaucoma. Primary congenital glaucoma refers to increased intraocular pressure occur ring at birth or shortly thereafter without an associated cause. Congenital glaucoma is extremely rare, occurring in fewer than 1 in 100,000 births. Normal intraocular pressure in infants is approximately 10 to 15 mm Hg,

Figure 12 6.

Chronically infected amniotocele with abscess in a 3-month-old infant. This patient was admitted to the hospital and treated with intravenous antibiotics several times but never probed. The infection did not clear until the nasolacrimal duct was probed. Early nasolacrimal duct probing in the first week of life should have been done and would have avoided this chronic infection. Probing of the nasolacrimal duct opened the obstruction, drained the abscess, and cured the infection.

whereas intraocular pressure in infants with congenital glaucoma is often higher than 30 mm Hg. Congenital glaucoma is very different from adult glaucoma. In adult glaucoma, increased intraocular pressure damages the optic nerve, but the eye size does not change. Infants, however, have a very elastic sclera and cornea, so increased intraocular pressure actually results in expansion of eye size and thinning of the eye wall (Figure 12 7 A and B).

Normal corneas at birth are approximately 10.5 mm in diameter; corneal diameters greater than 12 mm are considered abnormally large (megalocor nea). As the cornea enlarges, breaks of the basement membrane of the cor neal endothelium (Haab striae) occur. The most severe consequence of high pressure is optic nerve damage. Sustained high pressure results in a specific form of optic nerve atrophy and glaucomatous optic disc cupping changes. Figure 12 8 shows a large optic cup caused by glaucoma. After 3 years of age, the eye wall becomes fairly rigid, ocular enlargement secondary to glau coma does not occur, and the only structural damage is to the optic nerve.

Presenting features of congenital glaucoma include tearing, photophobia, blepharospasm, large cornea, and corneal clouding (edema), with approxi mately 70% of cases being bilateral. These classic findings of congenital glau coma are not always present, as ocular enlargement and corneal edema may be subtle (Figure 12 7C). Congenital glaucoma may be subtle, presenting

Figure 12 7.

A, Neonate with bilateral severe congenital glaucoma. Note the extremely large corneas and corneal edema that gives the bluish appearance to the eyes, indicating corneal edema. B, Congenital glaucoma right eye. Note the white corneal opacity, which is corneal edema secondary to increased intraocular pressure and a break in Descemet membrane (Haab striae). The corneal diameter of the right eye is 13.5 mm versus 11.5 mm in the left eye. C, Congenital glaucoma in a 2-month-old infant with mild bilateral corneal edema and slightly enlarged corneas. The right corneal diameter is 12 mm and the left corneal diameter is 13 mm. This child presented with epiphora and could have been easily misdiagnosed as having a nasolacrimal duct obstruction. A dim red reflex caused by the corneal edema indicated to the pediatrician that this was more than a common nasolacrimal duct obstruction.

primarily with tearing, thus prompting the misdiagnosis of nasolacrimal duct obstruction. In contrast to nasolacrimal duct obstruction, however, the tearing associated with congenital glaucoma is caused by corneal edema, which can be seen as a dull red reflex with an ophthalmoscope even if subtle to the naked eye.

The pathogenesis of congenital glaucoma relates to an abnormal outflow caused by abnormal angle structures, including the trabecular meshwork. Recent studies have identified a congenital glaucoma gene (2p21, 1p36) and juvenile glaucoma gene (1q23 q25). Juvenile glaucoma is a type of glau coma with onset after 2 to 3 years of age. It is difficult to diagnose because there are virtually no signs or symptoms other than increased intraocular pressure and optic disc cup changes (Figure 12 8).

Figure 12 8.

Top, Glaucomatous optic nerve (anterior optic nerve head and transverse view, right eye). Note the thinning and undermining of inferior neuroretinal rim and focal notching (FN) of inferior neuroretinal rim, enlarged central cup with visible laminar fenestrae (LF), nasal shift of retinal vessels, and peripapillary atrophy. Bottom, Glaucomatous optic nerve.

Advanced cupping with diffuse thinning and undermining of the neuroretinal rim, nasalization of the retinal vessels, and loss of the normal nerve fiber layer striations (right eye).

The treatment of congenital glaucoma is based on lowering the intraocu lar pressure to prevent optic nerve damage, prevent progressive expansion of the eye, and reduce corneal edema. Medications have been used to lower intraocular pressures and can include beta adrenergic inhibitors (timolol); carbonic anhydrase inhibitors, which can be administered topically or sys temically (Diamox); and in some cases, adrenergic agonists (apraclonidine). Medical treatment is not effective in most cases of congenital glaucoma, which is almost always a surgical disease.

Surgery is directed to opening the outflow channels at the trabecular meshwork. The 2 most frequently used procedures are goniotomy and trabeculotomy ab externum. With a goniotomy, a microscopic sized knife is used to lyse the abnormal trabecular meshwork to open up the angle. With the trabeculotomy ab externum, a microscopic probe is placed in the Schlemm canal and then swept through the trabecular meshwork and into the anterior chamber to open up the angle. The success rate of these procedures for congenital glaucoma is approximately 60% to 70%. If the first procedure fails, a second goniotomy or trabeculotomy ab externum may be performed. If these procedures are not successful, a trabeculectomy is usu ally performed. A trabeculectomy is a filtering procedure in which aqueous fluid is filtered through a small hole in the eye to the subconjunctival space. Lastly, if these procedures fail, congenital glaucoma can be managed by ciliary body destructive procedures such as cryotherapy and laser surgery.

These procedures work by eliminating the ciliary body epithelium that pro duces aqueous. These are end stage procedures and have a high failure rate.

The prognosis for congenital glaucoma is fair, with approximately 70% of patients maintaining good, long term visual acuity usually after one or more surgical procedures. Unfortunately, those who are in the unfavorable outcome group often go on to blindness. The most important cause of visual loss is attributed to optic nerve damage, which is not reversible. Other causes of uncorrectable low vision include chronic corneal edema with corneal scarring, refractive errors, and amblyopia from a blurred retinal image in early infancy.

Juvenile glaucoma is more amenable to medical treatment. In many cases, however, juvenile glaucoma must also be treated with surgical tech niques. Fortunately, juvenile glaucoma is extremely rare.

Secondary forms of congenital or juvenile glaucoma are associated with an ocular anomaly (eg, aniridia and anterior segment dysgenesis) or a

specific syndrome (eg, Sturge Weber syndrome, Weill Marchesani syndrome). Table 12 2 lists types of secondary congenital and juvenile glaucomas.

Table 12-2. Secondary Causes of Pediatric Glaucoma

Ocular Anomalies

1.Aniridia

2.Spherophakia

3.Anterior segment dysgenesis (Peter and Rieger anomaly)

4.Posterior pole tumors (retinoblastoma and medulloepithelioma)

Systemic Association

1.Sturge-Weber syndrome

2.Klippel-Trenaunay-Weber syndrome

3.Lowe syndrome (glaucoma and cataracts)

4.Neurofibromatosis

5.Marfan syndrome

6.Pierre-Robin syndrome

7.Rubinstein-Taybi syndrome

8.Trisomy 13

9.Rubella syndrome

10.Weill-Marchesani syndrome

11.Persistent hyperplastic primary vitreous (PHPV)

12.Retinopathy of prematurity (ROP)

13.Corticosteroid-induced glaucoma

Crocodile Tears

Crocodile tears is a term used to describe tearing secondary to mastica tion and gustatory stimulation. This occurs because there is an aberrant innervation of the lacrimal gland by the nerve to the salivary glands. The innervation is usually a result of a facial nerve injury causing secondary mis direction of the salivary fibers to the greater superficial petrosal nerve.

Dry Eye in Children

It may seem paradoxical, but a dry eye often presents with symptoms of tearing. A dry eye, either from corneal exposure or lack of tear production (hyposecretion), causes irritation to the corneal epithelium, stimulating reflex tearing. Exposure caused by poor eyelid closure is often associ ated with proptosis, lid retraction (shortening of lid skin and cicatricial

ectropion), lid defects (lid coloboma), and facial nerve palsy. Exposure can also be caused by lack of a blink response due to an anesthetic cornea.

Dry eye caused by hyposecretion of tears is rare in children and can be diagnosed by the Schirmer test. The Schirmer test is performed by placing a filter paper wick in the temporal fornix of the lower eyelid for 5 minutes to measure the amount of tear production. Normal wetting is a measurement greater than 10 mm; less than 8 mm indicates hyposecretion. Diffuse con junctival scarring also produces dry eye syndrome because of loss of mucus producing goblet cells and closure of accessory lacrimal glands. Conjunctival scarring occurs in diseases such as Stevens Johnson syndrome (see Chapter 13). Table 12 3 lists causes of pediatric dry eye.

Table 12-3. Causes of Dry Eye

•  Exposure (proptosis, eyelid retraction, lid coloboma, and poor blink response)

•  Hyposecretion (Riley Day syndrome—familial dysautonomia, hereditary alacrima)

•  Conjunctival   scarring (Stevens-Johnson syndrome, alkaline burn, ocular pemphigoid, vitamin A deficiency, trachoma)

Bibliography

1.Mocan MC, Najera Covarrubias M, Suarez N, Wright KW. Results of multi pass nasolac rimal duct probing. In: Balkan RJ, Ellis GS, Eustis HS. At the Crossings: Pediatric Ophthal mology and Strabismus. Proceedings of the 52nd Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, February 14 16, 2003. The Hague, the Netherlands: Kugler Publications; 2004:251–255