Lacrimal System Flashcards
what type of gland is the lacrimal gland
exocrine
what divides the two lobes of the lacrimal gland, and what are the two lobes?
lateral horn of the levator aponeurosis divides orbital and palpebral lobes
where should biopsy of the lacrimal gland be performed, and why?
orbital (because palpebral gland has lacrimal ducts running through it which can be damaged by biopsy)
what types of glands are Krause and Wolfring, and where are they located
both exocrine glands; Krause in the fornices, Wolfring at superior border of tarsus
name components of lacrimal drainage system in order
punctum, canaliculus, common canaliculus, lacrimal sac, valve of Rosenmuller, NLD, valve of Hasner, inferior meatus
what is another name for the posterior medial canthal tendon, and where does it attach
Horner muscle, attaches to posterior lacrimal crest
length of NLD
12-18 mm
which muscle is responsible for active pumping of most of the tear flow
orbicularis oculi
most common location of lacrimal cutaneous fistula
infranasal to medial canthus
- constant tearing suggests___
- constant tearing w/ mucopurulent discharge suggests ___
- intermediate tearing w/ mucopurulent discharge suggests ___
- canalicular obstruction
- complete NLD obstruction
- intermittent NLD obstruction
most common cause of congenital obstruction of the lacrimal drainage system?
membrane blocking valve of Hasner; 90% resolve spontaneously by 1 year
length and direction of canaliculus
2mm inferior, then bends for 8-10mm medial
soft stop on probing?
hard stop?
soft - usually obstruction
hard - usually kink in canaliculus created by bunching of tissues
management of congenital NLD obstruction
- start conservative: observation, lacrimal sac massage, topical or oral abx
- then probe if not resolved (90% will be cured with probing)
- stent if residual obstruction, use silicone stent (example: Crawford stent); 70% success rate
- balloon dacroplasty can be performed for refractory cases
- DCR is definitive management for refractory cases
intermittent epiphora and mucoid discharge from punctum, especially when associated with cold-like symptoms. probing reveals inferior turbinate lateralized against the NLD. treatment?
medial infracture of the inferior turbinate
small, nontender, slighlty bluish bump infranasal to medial canthus in newborn
dacrocystocele. treat like regular NLD obstruction
normal tear break-up time? what does abnormal value suggest?
10 seconds or more; abnormal suggests deficient mucin or lipid layer of tears
Steps to Schirmer test, and what is abnormal value?
apply topical anesthetic. place strip in inferior fornix for 5 minutes. abnormal is 15 mm
abnormal dye disappearance test?
persistence of sye past 5 minutes
reflux of saline from same canaliculus during irrigation? from opposite canaliculus? reflux of mucus?
same: canalicular obstruction
opposite: common canalicular obstruction
mucus: NLD obstruction
utility of NLD probing in kids v adults
- kids: useful b/c NLD obstruction usually due to thin membrane over valve of Hasner which can be fixed w/ probing
- adults: not useful b/c NLD obstruction usually 2/2 scarring which cannot be probed. irrigation is used for adults
treatment for punctal stenosis?
dilation for first line although has short lived effects. most patients will need punctoplasty (snipping small portion of ampulla). stenting for refractory cases
most common cause of enlarged puncta? how do these patients present?
iatrogenic (stenting, punctoplasty). present w/ epiphora (impaired punctal seal prevents negative pressure in lacrimal sac and therefor tears are not sucked through canaliculi effectively)
causes of acquired canalicular obstruction
trauma, punctal plug issues, chemo, infection, ocular cicatricial pemphigoid, Stevens-Johonson, graft-v-host, neoplasm
