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| OPHTHALMOLOGY | ARTICLE early or mild cases of dry eye syndrome. It will stain


the epithelial cells that are not protected by mucin tear coating. Other indicators include: ■ The tear meniscus is less than 1 mm thick and is losing its convex shape


■ The tear break-up time (BUT) with fluorescein stain is less than 10 seconds (the tear BUT is the time measured from a blink to the appearance of tear film defect)


■ SchirmerÕs test shows unanaesthetised measures of basal and reflex tearing (the norm would be more than 15 mm at 5 minutes)


■ Anaesthetised measures of basal tearing only (the norm is greater than 10 mm at 5 minutes).


The authors prefer to use anaesthetised methods to assess the patientÕs condition.


Surgical anatomy of the lacrimal system Tears in the marginal tear strip enter the lacrimal drainage system through the punctal opening of both eyelids (Figure 1). The puncta are located on the medial lid margin at the apex of small mounds of soft tissue. The papillae appear pale in contrast to the surrounding tissue as they contain more connective tissue and less vasculature. They are centred on the eyelid margin in line with the mucocutaneous junction. The upper papillae are located approximately 6 mm from the medial canthal angle and the lower papillae are 6.5 mm from the medial canthus. The punctal opening measures 0.2–0.3 mm in diameter and is surrounded by a ring of dense connective tissue that normally maintains a patent entrance. The aperture is round or oval in youth, but often collapses into a slit configuration with age. The puncta are normally directed somewhat posterior towards the globe and do not become visible unless the lid is slightly everted. For each punctum, a canaliculus passes perpendicular to the lid margin at a distance of 2 mm, where it dilates to form the ampulla, an irregular sac 2 mm in diameter. From the ampulla, the canaliculi turn horizontally and run medially, parallel to the lid margin for a distance of approximately 8 mm. In 90% of individuals7


, the two canaliculi join at an angle of


approximately 25 degrees to form a common canaliculus 3–5 mm in length8


. In the remaining 10%, the two canaliculi


join the lacrimal sac independently. The lacrimal sac passes inferiorly into the bony canal


Figure 3 Chedly Punctal Occluder in the canaliculus lumen


Thermal cautery has a higher


success rate than laser, but also has severe drawbacks. The energy cannot be adjusted easily in order to provide the right amount.


12 mm in length and 3–5 mm in width. Intranasally, the canal forms the lacrimal ridge, which runs in front of the middle turbinate and the medial wall of the ethmoid labyrinth.


Management strategies for severe dry eye syndrome The management strategy for dry eye syndrome will often depend on the severity of symptoms. The mainstay is the use of tear substitutes, such as artificial tears. Pharmacologic stimulation of tear secretion, such as with topical cyclosporine, has been tried with only minimal success9, 10


. Permanent punctal occlusion is indicated for severe


dry eye syndrome and minimal tear secretion. It is possible to achieve punctal occlusion using collagen or silicone plugs11


. However, one of the drawbacks of


punctal plugs is migration into the nasolacrimal system. This migration can cause canaliculus and lacrimal sac


Figure 4 Four-step diagram of insertion and retrieval of CPO


prime-journal.com | March 2012





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