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
CanaliculoDCR v ConjunctivoDCR v DCR
CanaliculoDCR: enter through canalicular system, resect obstructed segment, and anastamose canaliculus to lacrimal sac or lateral nasal wall mucosa
ConjunctivoDCR: bypass created from caruncle to new hole in nose (rhinostomy)
DCR: creation of anastamosis of lacrimal sac to nasal cavity through bony ostium
causes of acquired NLD obstruction
involutional stenosis, dacrolith, sinus disease, trauma, inflammatory disease, lacrimal plogs, radioactive iodine, neoplasm
treatment of choice for most patients with acquired NLD obstruction
DCR
benefits of endonasal DCR v external DCR
endonasal: less discomfort, no visible scar, quicker recovery
timing of repair of traumatic canalicular injury
ASAP, w/in 48 hours
effects of having only one functional canaliculus?
50% get intermittent or constant epiphora
utility of direct suturing of severed canaliculi ends back together?
usually not useful; using a lacrimal stent and restoring normal anatomy of surrounding tissues is suffiecient
in the absence of complications, how long are stents generally left in after traumatic canalicular repair?
2 months
most common viral cause of dacroadenitis
EBV
most common cause of infectious canaliculitis
Actinomyces israelii
initial treatment of canaliculitis
warm compresses, massage, topical or oral abx. curettage or canaliculotomy for refractory cases
approach to canaliculotomy for canaliculitis
conjunctival approach, only to horizontal portion, then leave open to heal by secondary intention
most common cause of dacrocystitis
complete NLD obstruction
management of acute dacrocystitis
- intubation and stenting are NOT recommended
- topical abx NOT useful
- oral abx most useful (GP bacteria, but suspect GN in diabetics and immunocompromised)
- I&D as needed for an abscess. IV abx for severe cases
- DCR is definitive treatment to prevent recurrence. this should be performed before elective intraocular surgery
