This test is most valuable when both sides are compared simultaneously, which results in an asymmetric tear meniscus. A thin or no fluorescein remaining indicates a positive test and probable normal drainage outflow. The scale range is 0 to 4+, with 0 representing no fluorescein dye remaining and +4 representing all the fluorescein dye remaining. Observations of the residual fluorescence of the tear meniscus are made at 5 minutes, and the thickness of the tear meniscus is measured and graded on a scale that can be used to quantify the thickness subjectively. Therefore, younger patients may be more symptomatic than older patients as tear production decreases with age.įluorescein dye disappearance test (FDDT): This physiologic test consists of staining the tear film using a fluorescein strip or instilling a drop of 2% fluorescein in the lower fornix. This epiphora not only depends on how complete the obstruction is but also on how many tears are produced. The tears then flow down the nasolacrimal duct to end at the inferior meatus of the nose.Īn abnormality partially or completely blocking anywhere along this path usually causes epiphora. Once the tears enter the upper and lower puncta, they flow into a vertical portion before entering the horizontal part of the canaliculi that ends at the lacrimal sac in the lacrimal fossa. Therefore, a healthy seventh cranial nerve-orbicular muscle unit, good eyelid position, and tone are required to complete tear film distribution across the ocular surface and down to the drainage path. As a result, this blink circle facilitates tears circulation from the punctum through the lacrimal sac and down to the nasolacrimal duct. Moreover, the orbicularis muscle (pretarsal and preseptal segments) should contract its fibers narrowing the palpebral fissure to spread the tear film toward the punctum. Thus, the upper eyelid should move downwards, touching the inferior eyelid with each blink and consequently picking up the tear meniscus for its distribution vertically. In addition, mechanical wiping of the tears can irritate the conjunctiva further, which causes reflex tearing and perpetuates the cycle.Įyelid movement must also be normal to facilitate proper tear film circulation across the conjunctiva and corneal surface. In cases where the neurosensory receptors from the trigeminal nerve in the cornea and conjunctiva are stimulated (i.e., neuralgia, conjunctival disease, corneal disease, ocular inflammation, or eyelid inflammation), there is increased lacrimal gland secretion (reflex tearing). Īny problems affecting any of these glands alter the correct composition of the tear film, which causes compensatory reflex hypersecretion. Outer lipid layer: produced by the meibomian and Zeiss glands - it reduces the evaporation of the aqueous layer. Examples of these techniques are dacryocystorhinostomy, silicone intubation, insertion of Lester-Jones tube, injection of botulinum toxin A into the lacrimal gland, and lid tightening. Consequently, different techniques have been used to tackle the problem with variable results. In addition, the different tests used in various studies to diagnose this condition were often non-comparable due to the absence of standardization. In contrast, for other authors, it is a diagnosis of exclusion. The suggested etiologies proposed by some authors include stenosis in the drainage system, lacrimal pump failure, edema at the nasolacrimal duct opening, tear hypersecretion, and nasal inflammation. However, there is no clear consensus about its diagnostic criteria and management.įunctional epiphora is a multifactorial disease whose management depends upon the suspected underlying cause or combination of causes. Endogenous (autoimmune) inflammation (such as sarcoidosis, Wegener granulomatosis, Kawasaki disease, cicatricial pemphigoid, Stevens-Johnson, sinus histiocytosis, or scleroderma) - these conditions may lead to obstruction of the lacrimal drainage system.įunctional epiphora is a common term used in the literature to report epiphora in the presence of an anatomic patent lacrimal drainage system.
0 Comments
Leave a Reply. |