Ch 36 Cont

Question 1

Etiopathogenical factors associated with dry eye disease acording to DEWS II definition

Answer 1

LINOS mnemonic:

Lacrimal instability 
Inflammation 
Neuro sensitive alterations 
Osmolarity changes
Surface disease

Question 2

Name differences of the closed-eye tears

Answer 2

Lower oxigen levels
Lower tear secretion and volume
Higher concentration of sIgA, PMN activity and chemotactive agents. Higher vasculogenic factors concentration.
Lower concentration of lactoferrin, lisozime, lipocaline and peroxidase

I’m normal conditions, these factors act as pathogen-defensive, and are down regulated as to avoid eye damage. In dry eye disease, the delicate homeostasis can be lost and the closed-eye tear may act as a pathogenic agent.

Question 3

Describe the pathogenic rol extracelular DNA y dry eye disease.

Answer 3

DNA released from de shedding of epithelial cells can gain access into other cells and activates:

1. INF mediated infmlamatikn
2. PMN chemotactic pathways

Neutrofils release DNA, chromatin, Histones and other components as part of its normal role. These form a net that has quemotactic, bactericidal, and infection-containing role. But the over concentration in the híper-osmolar environment of dry eye is toxic for the ocular surface.

Question 4

Describe de lacrimal reflex arch

Answer 4

Aference: 5th CN
Integration: superior salivary nucleus, caudal to the 7th CN ganglion
Eferente: parasimpathetic fibers emerge from the protuberance through the accessory-7th nerve, travel via-pterigoid channel nerve to the sphenopalatineganglion, post ganglion fibers travel through the lacrimal nerve.