Tono 1 Flashcards
Normal range
Mean
Daily fluctuation
10-21
15mmHg
2-6 mmHg fluctuation
5 factors exerting long term influence on IOP
Genetics: enlarged C/D, family history Age: As age increases, IOP increases Gender: Over 40, women have higher IOP Refractive error: Myopes have higher IOP Race:
Factors exerting short term influence of IOP
Diurnal variation- IOP higher in morning
Posture- IOP increases in all sleep positions
Exertional- decreases with exercise, increases with forced exhalation.
Lid and eye movement- increases with lid squeezing and up gaze.
Environment- decreases inc old air, increases when reduction in gravity.
Intraocular conditions: Decreases with retinal detachment, increases with inflammation.
Systemic conditions
Foods and drugs
How do intraocular conditions affect short term IOP
IOP decreases with retinal detachments due to RPE exposure draining vitreous fluid out.
Inflammatory response may cause increase.
How do systemic conditions affect short term IOP
IOP increase: HTN Hyperthermia Obesity Increased pulse rate and hemoglobin concentration In response to hormones and steroids
IOP decrease:
In response to progesterone, estrogen, relaxin, gonadotropin.
How does food and drugs affect short term IOP
IOP decreases with: Alcohol Fat free diet Heroin Marijuana
IOP increases with: Caffeine use Tabacoo/nicotine LSD Corticosteroids
Conventional outflow path
Corneoscleral meshwork Juxtacanalicular meshwork Internal collector channels Schlemm's canal External collector channels Empty into deep scleral plexus Then to episcleral and conj veins
3 ways that ciliary processes secrete plasma
Ultrafiltration, simple diffusion, aqueous humor
What does aqueous contain?
Ascorbate, hydrogen, chloride ions
No proteins- optically clear
How to calculate IOP
Rate of aqueous outflow / facility of aqueous outflow + episcleral venous pressure.
3 functions of aqueous
Transport nutrients
Provide internal pressure
Refractive media
Distribution of IOP in adult pop
Not perfect bell shape curve. 10% of adults have IOP higher than 21 mmHg.
Main disadvantage for goldmann
Only truly valid for 520 corneal thickness.
How is goldmann reading affected if cornea is greater than 540 micrometers?
How is it affected if cornea is less than 540 micrometers?
Greater = increase in pressure Thinner = Decrease in pressure
