What Are the Components of Lacrimal Apparatus and Where Are They Located?
Lacrimal glands (one in each eye) which are located in the upper outer part of the orbit, are under the edge of eyelid along with Ciaccio and Krause auxiliary lacrimal glands and produce the aqueous part of tear. In general, different layers of tear include:
- The innermost and thinnest layer is a thin layer of mucosa produced and secreted by conjunctival cells.
- The middle layer is the thickest layer and is actually like a very dilute solution of water and salt. Main and auxiliary lacrimal glands produce this part of tear. The function of this layer is keeping the eyes moist and repels dust and foreign bodies. Problem in the secretion of this aqueous layer is the most prevalent reason of dry eye which is called "keratoconjunctivitis sicca".
- The most superficial layer of tear is a very thin layer of lipid which is secreted by meibomian glands. The main function of this layer is to prevent from the evaporation of the watery layers below.
Tear is spread on the surface of the eyes and then enters lacrimal ducts and lacrimal sac through punctum, the two small pores which are on the inner edge of upper and lower eyelids, and finally enters the nose via the nasolacrimal duct. That is why we have runny noise while crying. Therefore, as can be seen in the following figure, lacrimal apparatus is composed of main and auxiliary lacrimal glands, lacrimal duct, lacrimal sac and nasolacrimal duct.
What Is Nasolacrimal (Lacrimal) Duct Obstruction?
The obstruction of the narrow nasolacrimal duct which drains tear from the surface of the eyes is called lacrimal duct obstruction. It is either acquired or congenital. We discuss its congenital form here.
What Is the Reason for Congenital Nasolacrimal Duct Obstruction?
Congenital nasolacrimal duct obstruction is prevalent among children. 6-10% of children are born before lacrimal duct is completely opened. Some sources state the prevalence of this disorder by 50% among infants. The reason for such an obstruction is that a membrane is left at the end of nasolacrimal duct on the nasal side.
What Are the Symptoms of Congenital Nasolacrimal Duct Obstruction?
The infants with this problem usually show symptoms 2 or 6 weeks after birth, the most prevalent of which is tearing. Newborns do not have reflex tearing while crying, that is, tear is most probably pathological in this period. Other symptoms of this illness include discharge, recurrent inflammation of conjunctiva and inflammation and infection of lacrimal sac, in which case, periocular skin will be red, inflamed and sensitive to touch. It may be swollen and mucous discharge may be seen inside the eye. In 1/3 of the cases, both eyes are involved. The symptoms in infants are intensified by dust and wind, but there is no photophobia.
Note: In children with extreme tearing and photophobia, congenital glaucoma should be considered.
How Can Obstruction Be Diagnosed?
- Gentle pressure on the lacrimal sac lets out the liquid from lacrimal punctum.
- Some materials such as flourescein are dropped into the eyes and, based on the time it takes to disappear or the time it takes to appear in oral pharyngeal cavity (which is evaluated by the blue light of cobalt), obstruction can be diagnosed or ruled out. Performing such a diagnostic method has special problems in infants. To do this diagnostic test, first, we drop flourescein 1% drop into the conjunctiva and wait for 2 to 5 min. In normal conditions, there should be no flourescein inside the eyes after 5 min.
What Is the Treatment for Congenital Lacrimal Duct Obstruction?
Congenital lacrimal duct obstruction in children is spontaneously improved in most cases so that lacrimal duct is usually opened before 1 year old in 95% of children. Interventional treatments of this disease include surgical and nonsurgical methods.
- Conservative (nonsurgical) treatment includes observation for resolution, massaging lacrimal sac and consuming topical antibiotics. Before giving a massage, it is required to wash the hands and put the index finger on the inner edge (nasal side) of the eye and press downward. Also, you may be asked to use warm compress. In case of infection, it is useful to apply an antibiotic drop or ointment. Note that antibiotics do not treat the obstruction.
- If lacrimal duct obstruction does not disappear after a few months in spite of the above treatments or in case severe infection occurs or your child has recurrent infections, it is necessary to probe, which is successful in children below 1 year old in 85-95% of cases. However, the chance of success decreases as the child grows up. Probing is a surgical method which lasts about 10 min and a thin metal probe is passed through the closed lacrimal duct in order to remove the obstruction. Some physicians believe that 6 months is the proper age in which probing can be done in a clinic without general anesthesia, but others believe that probing should be delayed by 1 year old to give the child the maximum chance of spontaneous opening of the duct. At this age, probing is done in the operating room under general anesthesia.
- If probing is unsuccessful or stenosis is found while doing that, more aggressive surgical measures such as silicone tube intubation might be necessary. In such a method, a silicon tube is placed inside the lacrimal duct for 6 months which will expand the duct. After this period, it is removed from the eye by a minor surgery.
- Balloon dacryoplasty: A more modern surgical method is balloon catheter dilation in which a balloon is placed on the corner of the eye inside the lacrimal duct. First, this balloon is expanded by a sterile liquid for 90 minutes and then the liquid is removed and the balloon is expanded again for 60 minutes; finally, the liquid is removed. The success rate of this method has been reported between 80 and 100%.
- In rare cases in which children still suffer from tearing despite the mentioned measures, DCR or dacryocystorhinostomy may be performed in children similar to adults. This method which is the original treatment for most patients suffering from acquired obstruction should be used in people who have recurrent dacryocystitis, mucoid fluid reflux, painful dilation of the lacrimal sac or tearing. Although there are different methods for treating this case, the main technique for all of them is to open a passing way through the lacrimal sac to the nasal space.