INTRODUCTION
Tearing is a common symptom of many ocular and sometimes even systemic illnesses. A thorough understanding of the lacrimal apparatus, tear film and lacrimal drainage system is necessary in order to determine the cause of a patient’s tearing. Tearing is often classified into two entities: lacrimation or excess production of tears, and epiphora which is overflow of tears due to blockage of the lacrimal drainage system.
OBJECTIVES
Upon completion of this instructional material, the student should be able to 1. define the symptom of tearing (differentiate between lacrimation and epiphora) 2. enumerate the common conditions that cause tearing.
3. enumerate and describe the different clinical examinations which can help determine the cause of tearing.
4. provide basic clinical (diagnosis and management) information regarding the different types of nasolacrimal duct obstruction.
PREREQUISITE KNOWLEDGE AND PREPARATION 1. Anatomy of the eye, ocular adnexae, particularly the lacrimal drainage system 2. Physiology of the lacrimal drainage system
3. Basic ocular examination (normal and abnormal findings) INTENDED USERS Year Level IV UPCM Medical Students
CONTENT
Tearing or ‘watery eyes’ is a common ocular symptom which has numerous causes ( Appendix A). Chronic tearing can be a debilitating complaint which may be a nuisance (constant need to wipe off the tears), source of embarrassment and discomfort for the patient. Tearing is either due to increased production (lacrimation) or from impaired drainage (epiphora).
The tear film has unique characteristics (Table 1). It is composed of three layers: an outer oily layer (oily secretions from Meibomian and Zeis glands), a middle aqueous layer produced by the lacrimal gland and glands of Krause and Wolfring, and an inner mucinous layer secreted by the goblet cells of the conjunctiva.
The superficial oily layer functions to prevent the evaporation of the aqueous layer. The pH of tears averages 7.4. The mucous layer is important for proper wetting of the cornea.
The lacrimal drainage system begins at the punctum leading to the canaliculus to the lacrimal sac down to the nasolacrimal duct. The duct opens at the inferior meatus under the inferior turbinate. See Illustration below, note 1 = valve of Rosenmuller, 5 = valve of Hasner (opening at inferior meatus underneath the inferior turbinate)
We must keep in mind that the amount of tears in our eye is dictated by three factors: production, evaporation and drainage. Conditions that increase production and impair drainage will result in a surplus of tears in the eye, while increased evaporation (decreased humidity, prolonged reading, eyelid retraction, etc) will lead to a relative lack of tears.
Increased Tear Production (Lacrimation)
Tearing is more commonly caused by increased production. It is very important to get a thorough history and physical examination in order to determine the cause of tearing. It is important to ask for: history of trauma, eye redness, use of medication, photophobia, and blurred vision. Patients who complain of ‘foreign body sensation’ can have conditions such as: corneal or conjunctival foreign body, misdirected lashes, corneal ulcer, etc. Tearing in these situations is the body’s attempt to wash out the eye of the ‘irritant’.
Important questions to be asked in a patient’s history include the following:
1. History of trauma – to rule out conjunctival or corneal foreign bodies, corneal abrasions. Certain occupations (i.e. carpenters, construction workers etc) are predisposed to foreign bodies in the cornea or conjunctiva. Lacerations may involve the lacrimal gland or any part of the drainage system which can affect the amount of tears present in the tear lake. Canalicular lacerations should be suspected when there is a lid margin laceration within 5 mm of the medial commissure.
2. Associated symptoms – discharge (water, mucoid or purulent), redness, eye pain, blurring of vision, foreign body sensation, itchiness. Exposure to someone with similar ‘red eyes’ may suggest a form of viral conjunctivitis, while allergies are often associated with itchiness.
3. Consultations with a doctor and medications used, history of ocular surgery. This may suggest a chronic process or may be a result of patients surgery. It is important to establish a timeline of consultations, surgeries, and medications used in order to figure out when the symptoms started and how they responded to therapy.
4. Onset and duration of tearing (Worsening during prolonged reading or when exposed to wind may indicate a ‘dry eye’. While reading or working with the computer, we tend to blink ‘less often’ resulting in more tear evaporation. These situations uncover the presence of dryness or ‘tear instability). Dry eye more common in the elderly, nasolacrimal duct obstruction is more common in women.
5. Other medical problems particularly allergies, sinus disease
A thorough ocular examination (visual acuity, gross examination, EOM, tonometry and funduscopy) is necessary to determine the cause of a patient’s tearing. Examination for patients with lacrimation should focus on the anterior segment examination. Any injury or inflammation involving the lashes, cornea, conjunctiva, anterior chamber and iris will result in some form of tearing. Ectropion and entropion may cause ocular irritation resulting in tearing.
Slit lamp biomicroscopy utilizes a microscope with a light in order to magnify the structures in the eyelids and anterior segment of the eye, with the slit beam providing other details as presence of anterior chamber inflammation, anterior chamber depth, corneal clarity, lens clarity, etc. A slit lamp may be used in conjunction with a Goldman’s applanation tonometer in order to determine a patient’s intraocular pressure.
Note. Patients with Dry Eye can also manifest with tearing. Generally, patients with mild to moderate dry eye may complain of tearing which is mostly a reflex mechanism to compensate for the ‘lack of tears’. Slit lamp examination may show an abnormal tear meniscus, decreased production of tears may be confirmed by doing the Schirmers test.
Tests for patients with Lacrimation
Schirmers Test: uses a Whatman filter paper in order to measure the amount of wetting (from tears) in five minutes. A Schirmers strip is folded and placed at the junction of the lateral and middle third of the lower eyelid. Patient is asked to look straight ahead and avoid blinking. Schirmers Test can be done with and without anesthetic (Proparacaine). Schirmers Test with anesthetic is thought to measure basal secretion of tears while the test without anesthetic measures reflex tearing. A Schirmers Test with anesthetic wetting of 5 mm or less in 5 minutes is indicative of dry eye.
Management of Lacrimation is generally directed to address the underlying cause of tearing. Management will range from antibiotic eyedrops for patients with bacterial infections, removal of foreign bodies for patients with conjunctival or corneal foreign bodies, eyelid surgery for patients with misdirected lashes, entropion or ectropion, etc. Correction of these conditions will result in the resolution of the patients tearing.
Thickness 7 – 10 um
Layers 3 Thickness of the Aqueous Layer 6.5um
Tear Volume 6 – 8 ul
Tear Production 1.2ul per minute
Table 1. Characteristics of the Tear Film Decreased Tear Drainage (Epiphora)
Tearing due to blocked tear drainage can be a very bothersome symptom. Patients frequently carry along boxes of tissue paper in order to constantly wipe off overflowing tears. Chronic epiphora can sometimes lead to infections of the lids and lacrimal sac.
Any point of the lacrimal drainage system can be blocked, from the punctum to the canaliculus, lacrimal sac, and the nasolacrimal duct. Punctal stenosis can be visualized directly or with the use of a slit lamp.
order to diagnose nasolacrimal duct obstruction. Blockage may be due to scarring from inflammation or topical medicines, from injury (canalicular transections), or from tumors (lacrimal sac tumors, dacryolithiasis).
Punctal ectropion associated with lid laxity can contribute to decreased outflow of tears. Conditions such as Bells palsy or weakness of the CN7 may also cause physiologic pump failure of the lacrimal drainage system.
Nasolacrimal duct obstruction should be suspected in patients with tearing who have normal anterior segment examination (i.e. no abnormal finding which can explain the patients tearing). Patients often have a long standing history of on and off tearing of the involved eye, with or without history of infection (mucoid discharge, conjunctivitis, dacryocystitis). Patients with dacryocystitis often have history of swelling of the medial canthal area which when exacerbated results in: pain swelling and erythema (acute dacryocystitis).
Primary acquired nasolacrimal duct obstruction is more common in elderly females.
Diagnostic Tests:
1. Probing : a fine blunt probe can be inserted through the punctum and canaliculus in order to determine the patency of the upper lacrimal drainage system. Probing may also be confirmatory for patients with canalicular transactions due to trauma.
Picture 1. (on left): A Gauge 25 Lacrimal Irrigating Canula is inserted through the punctum (exits at the distal cut end of the canaliculus), confirming presence of canalicular laceration
2. Lacrimal Apparatus Irrigation: involves the irrigation of normal saline solution through the punctum and canaliculus, reflux (either thru the upper canaliculus or lower canaliculus) would indicate an obstruction.
3. Palpation of the lacrimal sac area: applying pressure on a distended lacrimal sac may result in mucoid reflux, which confirms the presence of nasolacrimal duct obstruction. Obstructions involving the canaliculi or puncta will not result in distension of the sac since the tears will not be able to reach the sac.
4. Dye disappearance test: assesses the presence or absence of adequate lacrimal drainage. Fluorescein is instilled on the cul de sac of both eyes. Asymmetric clearance of the dye within 5 minutes indicates relative block in the side with dye retention. Retention of dye beyond five minutes in one eye is also indicative of blockage. The DDT does not distinguish between mechanical blockage and functional blockage.
Management of nasolacrimal duct obstruction is surgical. A dacryocystorhinostomy is performed for adult patients with symptomatic and complete nasolacrimal obstruction. It involves a fistulizing procedure, connecting the lacrimal sac to the nasal mucosa. The surgery is performed under general anesthesia.
Special Topic:
Congenital Nasolacrimal Duct Obstruction: is present in up to 10% of all normal infants. Pathology is an imperforate membrane at the Valve of Hasner at the inferior meatus. Children presents with tearing or chronic eye discharge / recurrent conjunctivitis, while severe cases present with fulminant dacryocystitis.
Diagnosis is usually confirmed by doing a dye disappearance test. Mucoid reflux upon digital pressure at the lacrimal sac area also confirms the diagnosis. About 90% of cases will resolve during the first year of life and spontaneous resolution continues even up to the 2nd year of life. Management of uncomplicated (i.e. no signs of infection, Dacryocystitis) is lacrimal sac massage. Persistent cases are managed with therapeutic probing
(rupturing the membrane at the Valve of Hasner) which is usually performed at 12 months of age. Patients who have undergone failed probings are managed with bicanalicular intubation with silicone tubes or by performing a dacryocystorhinostomy.