Congenital Nasolacrimal Duct Obstruction Biology Essay

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Conclusion A focused history and examination can differentiate epiphora due to nasolacrimal duct obstruction from other common or serious diagnoses. Parental education is a key issue in the management, as the conservative approach is advised initially, and referral for surgical treatment is reserved only for persistent cases.

A 2-month old infant is brought to consultation by its parents who describe epiphora and mucous discharge since the second week of life.

What is CNLDO?

Congenital nasolacrimal duct obstruction (CNLDO) is a common problem in the early years of life and one of the main causes of epiphora in infants1, with an estimated incidence that varies widely (1.2% to 30%), depending on the employed diagnostic criteria2. It is thought to result from a delay in maturation of the nasolacrimal outflow system, and in particular a failure of its canalization process, more commonly in its lower end.2,3

How does the child present?

Apart from the watery eye due to tear drainage failure, typically appearing in the first 2-4 weeks of life, the main other sign is mucous discharge, either constant or intermittent, and possible associated skin redness and excoriation around the eye, as well as "stickiness" of the child's lids and lashes following sleep. Frequent attacks of conjunctivitis, with mucopurulent discharge and red eye, often complicate the condition. If more severe infection occurs, there may be chronic or recurrent bacterial blepharitis, or dacryocystitis that can, if uncontrolled, lead to orbital cellulitis3.

A rare variant of CNLDO (accounting for only 0.1% of CNLDO cases), regarded by some as a complication, is the development of a mucocele or dacryocystocele2,3, which is formation of a dilated part of the lacrimal sac/duct, as a consequence of simultaneous proximal and distal obstruction. Its typical presentation is a bluish, cystic, firm mass below the medial canthus. Its clinical significance lies in the fact that if a cystic expansion protrudes into the nose, there may be respiratory distress and this requires more urgent intervention. Furthermore, dacryocystitis occurs more commonly in this context. Thus, if resolution is not achieved within a few weeks from presentation, early intervention is suggested by authors, to avoid these serious complications.

What should the history and examination include?

Epiphora, increased tear meniscus and mucous discharge are considered the typical features of CNLDO 2,4,5. History and physical examination help exclude a number of other conditions (Tables 1,2,3).

On examination, an increased tear meniscus and crusting and mattering of the lashes are evident. Enlarged lacrimal sac and regurgitation of mucopurulent material on compression of the lacrimal sac may also be noticed2,3.

Although in the past, syringing was used to examine CNLDO, nowadays the clinical findings of the ocular examination, can be reliably and non-invasively confirmed with the use of the fluorescein disappearance test (FDT), with a sensitivity of 90% and a specificity of 100%6. FDT is performed by instilling 0.5% proparacaine or other topical anaesthetic drop, followed by one drop of 2% fluorescein or a moistened fluorescein filter paper strip into the conjuctival cul-de-sac of each eye. The child is examined in a semi-darkened room from a distance of 3-4 feet with a cobalt blue filter light. Normal tear flow allows virtually all dye to be cleared from the tear meniscus within 5 minutes, while an obstructed nasolacrimal duct results in residual dye in the tear meniscus3,6.

What do you need to exclude?

- Increased lacrimation from irritation caused by epiblepharon, entropion, latent foreign body or from inflammation (keratitis, uveitis)

- Congenital glaucoma: epiphora in an irritable baby with photophobia, corneal clouding or enlargement, Haab's striae (Table 3)

What management should you provide?

Parental education2

Explain etiology, and reassure. Parents are often very distressed by the lengthy course of the disease, and may even feel guilty or be accused by their community of not taking good care of their child.

Alert them to signs of complications (bacterial conjunctivitis, dacryocystitis, orbital cellulitis)

Instruct correct technique of lid hygiene and nasolacrimal duct massage (Figure 1):

Cleanse lids and lashes with cooled boiled water(from nasally to temporally) as often as needed

Press with index or little finger or cotton tip. Also possible to apply vaseline or liquid paraffin to facilitate sliding on the skin without irritating it, 2-3 times a day

a) on the lacrimal sac: situated in the nasal bone, just below the medial canthus, and

b) stroke firmly upward to express contents of sac, and

c) stroke firmly downward, along the nasolacrimal duct, to increase hydrostatic pressure within it and possibly aid in the rupture of the membranous obstruction (technique described by Crigler in 1923).

Use of antibiotics

When signs of superimposed infection occur2:

- conjunctivitis (red, sticky, irritable eyes). Topical antibiotics such as chloramphenicol eyedrops, fucidic acid eyedrops, tobramycin eyedrops, can be used.

- dacryocystitis (mucopurulent discharge, redness, warmth of the skin over the sac). You need to administer systemic antibiotics. Do not probe during this acute phase: there is increased risk of creating false passages during probing.

- rarely, orbital cellulitis, from expansion of acute dacryocystitis. Need for hospitalization and intravenous antibiotics.

It is crucial to administer antibiotics with prudence and to instruct compliance with the duration of treatment, so as to avoid unnecessary, repeated administration that encourages development of resistant strains7. It is of note that acute bacterial conjunctivitis is a self-limiting disease where topical antibiotics only modestly speed up the resolution of symptoms, so observation is a legitimate option without significant risk8.

When is it indicated to swab?

When you suspect ophthalmia neonatorum or chlamydial conjunctivitis.

When should you refer?

The ideal time for surgical management, hence need for referral, remains a major subject of controversy. Some studies suggest that late intervention is a risk factor for failure4,9. Others, however, have shown that the higher failure rate in older children is not associated with the older age itself but appears to be a result of accumulation in this group of the more severe cases that have not spontaneously resolved5,10.

Spontaneous resolution or resolution after conservative management has a very high rate during the first year of life5,11. More than 65% of CNLDO cases show resolution with conservative treatment during the first 6 months of life and more than 80% during the first 12 months, while in infants aged between 6 and 10 months, more than half of eyes with CNLDO will resolve within 6 months with non-surgical treatment11,12. There appears to be no baseline characteristics (age, sex, laterality etc.) that may be associated with the probability of NLDO resolving without surgery13. The natural history of the condition suggests that, in infants less than 1 year old, a "wait-and-see" approach while applying conservative treatment, is advisable3,14, and this seems to reflect current practice15.

In patients older than 1 year, persistent obstructions usually require probing, although the optimal timing for this again remains controversial14. Factors affecting success are perhaps more of interest, as there appears to be no cutoff age after which intervention yields no results (Table 4). However, authors also disagree on these factors predictive of intervention outcome, for example bilaterality of NLDO is associated with higher risk of probing failure in some studies9,17, but not in others4,10. One factor that seems to be associated with higher failure rates, in all studies where it was investigated, is the "tight" or "firm" or "complex" obstruction of the nasolacrimal passage, encountered during probing9,10,17.

Amblyopia risk factors screening

Recent studies suggest that infants with CNLDO are at higher risk of having amblyopia risk factors than the general population18, so in persistent cases, there is an additional reason for referring them to an ophthalmologist, apart from the indication for intervention. These infants need to undergo an orthoptic examination and cycloplegic refraction, to detect potential refractive error or strabismus that are amblyogenic and need treatment18.

1305 words +481 (table) + 63 (legend) =1849

Contributions All the authors have contributed to the writing of this document

Competing interests None

Provenance and peer review

Table 1

Ask about2:

Epiphora between episodes of mucopurulent discharge

If absent, consider other diagnosis, e.g.

viral infection

chronic conjunctivitis (swab for chlamydia)

occult foreign body

Epiphora only at the time of congestion of nose, paranasal sinuses

Refer to ENT

Lacrimation when sucking or chewing (crocodile tears)

Congenital cranial dysinnervation disorders

Photophobia (with epiphora)

Congenital glaucoma to be excluded - refer to ophthalmologist

Atopic disease

Although rare in infants, allergic conjunctivitis presence of other

Table 2

Inspect2:

Lids

- Abnormalities, malposition

- Entropion (inward turn of the lid with eyelashes rubbing on the cornea)

- Epiblepharon (with associated eyelashes rubbing on the cornea)

- Small molluscum lesion (causing chronic conjunctivitis)

- Vesicles (herpes simplex blepharoconjunctivitis)

- S sign (drooping of the lateral aspect of the upper lid), signifying lacrimal gland enlargement, as in dacryoadenitis

Eyelashes

Distichiasis (multiple rows of lashes), rubbing on the cornea

Lacrimal puncta (superior & inferior)

In their absence or in presence of supernumerary expect abnormal anatomy of the upper nasolacrimal system

Tear film

Normally is virtually invisible, when stained with fluorescein measures less than 1 mm. In NLD obstruction, it measures >=2 mm

Conjunctiva

In "white eyes", no need to treat with antibiotics

Cornea

Evaluate its

Size (increased in congenital glaucoma)

Clarity (generalized haziness in congenital glaucoma, localized in keratitis)

Staining (use fluorescein drops and cobalt blue light to depict corneal abrasions)

Table 3

Differential diagnosis of watering eye (excessive lacrimation)2:

Differential diagnosis

Check for

Conjunctivitis gfgf(primary)

- history: absence of lacrimation/discharge in between episodes of red&sticky eye

- consider Herpes Simplex Virus, Molluscum contagiosum, Chlamydia, Actinomyces canaliculitis (rare)

- may have associated discharge from nose (watery or mucopurulent)

- allergic conjunctivitis (rare) if other atopic disease is present

Glaucoma

- history of photophobia

- generalized corneal haze (resulting from oedema)

- increased corneal diameter

Uveitis

Other signs:

- hypopyon

- irregular pupil shape and abnormal pupil reflex, secondary to posterior synechiae

- cataract (check red reflex)

May also have photophobia

Corneal abrasion, scar, ulcer, foreign body

Use fluorescein staining of the tears & cobalt blue light to examine corneal surface (abnormal epithelium stains with fluorescein and is seen as yellow-green uptake on the cornea)

May also have photophobia

Dacryoadenitis

Upper lid "S sign" and systemically unwell

Ophthalmia neonatorum

To consider when age<1 month and history of vaginal delivery, to confirm by conjunctival swab, to treat topically and systemically in patient and in parents

Table 4.

Comparison of success rates of probing by age group (months of age)

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