Dry eyes

 

 

Anatomy and Physiology:

The tear film provides corneal lubrication, nourishment and protection, has anti-infective properties, aids removal of bacteria, cells, and debris, and optimizes the optical interface between air and cornea.

It is triphasic, comprising a mucoid layer (from goblet cells), aqueous layer (primarily lacrimal glands but also accessory glands of Krause and Wolfring), and lipid layer (meibomian glands).

Symptomatic watering results from reduced tear removal (by evaporation and drainage) and/or overproduction. Obstructive epiphora refers to reduced tear drainage.

Tear distribution is also important, as is eyelid movement (‘lacrimal pump’) and position.
Patient tolerance of watering varies widely.

Consider the lacrimal drainage system as three compartments:
1. Tear lake.
2. Lacrimal sac.
3. Nasal cavity.

Relatively high-resistance conduits connect these compartments; the canaliculi, and nasolacrimal duct :

■ Canalicular obstruction produces ‘flow’ symptoms: ‘Eyes well up with water’, blur on downgaze, e.g. reading. ‘Volume’ symptoms are minimal or absent.

■ Nasolacrimal duct obstrucition (NLDO) produces ‘volume’ symptoms due to backwash from the lacrimal sac. These include: recurrent conjunctivitis; morning stickiness; mucus
debris in the tear film; dacryocystitis; lacrimal sac mucocele or abscess.

 

History:

Assess the severity of symptoms. Ask about the onset, time relationships, duration, and site of tear spillover.

Medial spillage suggests impaired drainage; lateral spillage may relate to lower lid laxity, or upper lid dermatochalasis contacting the tear film with chronic skin wetting by capillary action.

Reflex watering from tear-film deficiency is often worse in dry, warm conditions, bright light, or when blinking is reduced, e.g. concentrating on reading, computer use, and Parkinson’s disease.

The simultaneous runny nose suggests overproduction. Bloody tears suggest a sac tumour (rare), canaliculitis, or trauma to the canaliculi/sac (including iatrogenic injury).

Ask about surface irritation or itch (atopy), a history of facial/nasal trauma, and previous nasal or lacrimal surgery. ‘Crocodile tears’ are associated with facial palsy and involve neurogenic reflex watering, often sudden, from the thought of food, eating, or chewing. Lacrimal sac swelling may be secondary to a dacryocele (a congenital cyst), mucocele, pyocele, dacryocystitis (painful), tumour (usually painless ± bloody tears), or occasionally air.

Examination

Examine for causes of overproduction or impaired drainage

• Overproduction:

Look for:
1. Lid or lash malposition – trichiasis, distichiasis, entropion.

2. Lid margin disease.

3. Tear film deficiency – perform Schirmer’s test and tear film break-up time.

4. Corneal or subtarsal foreign body.

5. Conjunctivitis – look for allergic papillae, follicles.

6. Corneal disease, especially superficial punctate keratopathy from tear film anomalies or exposure keratopathy, and early dendritic keratitis.

7. Uveitis, scleritis.

■ Impaired drainage: Look for:

1. Eyelid laxity or malposition of the lower lid or punctum particularly ectropion.
2. Punctal or canalicular stenosis-cicatrizing conjunctivopathy, systemic chemotherapy, especially 5 FU and trauma (including iatrogenic).
3. Canaliculitis.
4. Fistula – congenital, or acquired (following dacryocystitis).
5. Lacrimal pump failure – especially facial palsy.
6. Lacrimal sac mucocele – this is a chronic collection of mucopurulent material due to low-grade colonization infection of stagnant tears. Pressing on the sac produces
mucus or pus reflux. A dacryocystorhinostomy (DCR) is often required for associated epiphora.
7. Lacrimal sac mass – consider tumour or tense mucocele. In general, a mass below medial canthal tendon (MCT) originates from the sac; lesions above the MCT indicate non-sac origin.
8. Dacryocystitis – active or resolved.
9. Nasal obstruction, e.g. mass, inflammation, scarring. If it is possible to gently pass a cotton bud alongside the lateral wall of the nose, this suggests a reasonable nasal airway is present; if not, consider an endoscopy.
10. Altered facial/lid relationship – this may include prominent eyes, lower lid sag and hypoplastic midface.
11. Prior surgery or trauma – look for scars.

■ Overproduction: Look for:

1. Lid or lash malposition – trichiasis, distichiasis, entropion.
2. Lid margin disease.
3. Tear film deficiency – perform Schirmer’s test and tear film break-up time .
4. Corneal or subtarsal foreign body.
5. Conjunctivitis – look for allergic papillae, follicles.
6. Corneal disease, especially superfi cial punctate keratopathy from tear fi lm anomalies or exposure keratopathy, and early dendritic keratitis.
7. Uveitis, scleritis.

■ Impaired drainage: Look for:

1. Eyelid laxity or malposition of the lower lid or punctum particularly ectropion.
2. Punctal or canalicular stenosis-cicatrizing conjunctivopathy, systemic chemotherapy, especially 5 FU and trauma (including iatrogenic).
3. Canaliculitis, this is a condition were Canaliculi become grossly dilated with intraluminal deposits caused by low-grade infection, classically Actinomyces, but also fungi. Symptoms of Chronic discharge. Epiphora is often mild but worse in mornings.

Signs Swollen inflamed lid medial to prominent ‘pouting’ punctum. Features may be subtle. Management Canaliculotomy: dilate and open 5 mm of the horizontal canaliculus. Use a fine chalazion curette to remove deposits. Send for microbiology. Prescribe G. chloramphenicol q.d.s. 1–2 weeks ± penicillin 250 mg p.o. q.d.s. for 1–2 weeks if severe.

Penicillin G drops (100 000 U/mL) may be used if there is a poor response to surgery, but canalicutomy is all that is required for most patients

4. Fistula – congenital, or acquired (following dacryocystitis).
5. Lacrimal pump failure – especially facial palsy.
6. Lacrimal sac mucocele – this is a chronic collection of mucopurulent material due to low-grade colonization/ infection of stagnant tears. Pressing on the sac produces mucus or pus reflux (Fig. 2.2). A dacryocystorhinostomy (DCR) is often required for associated epiphora.
7. Lacrimal sac mass – consider tumour or tense mucocele. In general, a mass below medial canthal tendon (MCT) originates from the sac; lesions above the MCT indicate non-sac origin.
8. Dacryocystitis – active or resolved.
9. Nasal obstruction, e.g. mass, inflammation, scarring. If it is possible to gently pass a cotton bud alongside the lateral wall of the nose, this suggests a reasonable nasal airway is present; if not, consider endoscopy.
10. Altered facial/lid relationship – this may include prominent eyes, lower lid sag and hypoplastic midface.
11. Prior surgery or trauma – look for scars.

how DCR is made and what is DCR