IOP Flashcards
what is the “magic number for IOP?
- greater than this is at risk for glaucoma but does vary. this is just a standard.
Refractive error has association with the amount of pressure in eye. T or F
False. It has no association.
Everyone IOP goes up with age. T or F
True
IOP depends on parents. T or F
True
Females have greater IOP after 40 yrs, whereas males have it 20-40 yrs old. T or F
True
when is IOP GREATEST? IN WHAT SEASON
WINTER
name factors that affect IOP in short term?
1) Diurnal variations
2) Postural variations: Supine cause increase
3) Exercise: Decrease in IOP (if done properly)
4) Blinking and forceful closure causes increase
5) Activities causing Valsalver maneuver
6) Trying to exhale with mouth closed
7) Eye movements
name long term affects of IOP?
genetics, age, gender, seasons, NOT REFRACTIVE EROR.
NAME DRUGS THAT CAN HAVE AFFECT ON IOP?
Alcohol: decrease in IOP
Caffeine: cause slight increase
Tobacco: May cause transient increase in IOP
Heroin and Marijuana: decrease in IOP
Food cannot have an affect on IOP. T or F
False.
what does a pneumotonometer do?
Pneumotonometer= measure blood flow to eye IOP
what is tonometry used to measure?
pressure in the eye
W = P x A
Where W= external force A=Area P pressure inside sphere what law was this? for what?
Imbert- Fick Law for tonometry.
what were the problems with Fick-Lambert’s Law working with the eye?
perfect sphere, dry, infinitely thin. The eye is none of this.
what factors can affect IOP measurements?
1) Central corneal thickness
2) Corneal curvature
3) Age related changes to cornea
4) IOP effects on cornea
5) Biomechanical properties
6) Rigidity
7) Hydration
8) Elasticity
Tissue and similarly the cornea are elastic or viscoelastic?
viscoelastic
IN FLAT CORNEA= OVERESTIMATE PRESSURE (LARGER RADIUS OF CURVATURE)
STEEP CORNEA= UNDERESTIMATE PRESSURE (SMALLER RADIUS OF CURVATURE)
True or False
True
IF CORNEA IS THIN= UNDER ESTIMATE PRESSURE
CORNEA IS THICK= OVERESTIMATE PRESSURE
NORMAL 520 MICRONS CORNEAL THICKNESS
True or False
True
Thickness of the cornea dictates how much pressure is in eye. True or False
False
the majority of blood flow to the eye comes from where?
the choroid
Name types of telemetry? name some
Non invasive- temporary CL’s continuous applanation or indentation devices Invasive- permanent Subconjunctival anterior chamber implants in AC as IOL haptics Scleral buckle scleral fixated sensor Posterior chamber implants –choroidal
With each pulsate your eye changes shape. T or F
True
what does telemetry measure?
IOP number of pulsates
what is a new advancement in telemetry where we can measure a patient eye non-invasive 24/7 IOP?
wireless CL (contact lens)
