Into to Cornea Anatomy

Power of the Eye 1. Total power of the eye is appx: ____D -_____D 2. Cornea provides about _____ D 3. Crystalline Lens provides about _____D

1. 60-65D 2. 45D 3. 20D

Radius of Curvature of the Cornea 1. Anterior cornea is ________ mm (_____ curved) 2. Posterior cornea is _____ mm (______ curved)

1. 7.8 mm 2. 6.5 mm

On average, the cornea is how thick in the center, and how thick near the limbus?

1. Center: 0.530mm (530 microns) 2. Near Limbus: 0.710mm (710 microns)

What are the 4 main functions of the cornea?

1. Transmit light to the retina 2. Aid in focusing the light on the retina (refracts light) 3. tough, exposed to the world to protect against infection 4. encloses the eye, maintains pressure and balance of the interior chambers

what is keratoconus?

1. disease that affects the shape of the cornea (cone shaped)

what are three findings in keratoconus that we see?

1. iron deposits at the base of the cone 2. ectasia (thinning) 3. corneal scarring

1. A thicker cornea would ____ -estimate the IOP 2. A thinner cornea would _____-estimate the IOP

1. over (artificially high) 2. under (artificially low)

The cornea as a refracting surface: 1. needs ____ surfaces 2. minimal scatter= no _____ vessels 3. right amount of water for spacing of _____

1. smooth 2. blood 3. fibrils

A soft contact Lens is usually how big?

13-14mm

mm --> micron?

1mm= 1000 microns

Example: We know the avg. corneal thickness is 530 microns. You measure IOP to be 22mmHg You check pachymetry, and it is 600 microns. Is the actual IOP closer to 24 or 20 mmHg?

20 mmHg

why do we care about the ROC of the cornea?

GP lens fittings diseases

What is an example of an oblate cornea?

Post-Lasik

What is an oblate cornea?

When the cornea is flatter in the center and steeper in the periphery

What is a prolate cornea?

When the cornea is steeper in the center, and flatter around the periphery

What are the dimensions of the cornea?

appx. 12mm across and 11mm high

What is Astigmatism?

change in corneal shape and curvature which creates two points of focus on the retina

The cornea ends at the ___-____ ____

corneal-limbal sulcus

What is Vogt's Striae in Keratoconus?

fine folds in posteror cornea

What is corneal pachymetry?

measure of corneal thickness

what kind of shape does the cornea have?

normally, an elliptical shape steeper in the center, flatter around the periphery

In general, the cornea is ____ and ____ in the center

steeper and thinner

What does normal corneal topography look like?

steeper in the center, flatter in the periphery

What does against the rule astigmatism look like?

steeper side to side

What does with the rule corneal astigmatism look like?

steeper top to bottom

What is the cornea?

transparent, outer connective tissue of the eye

Flip over: scarring, cone shape = kerataconus

what findings do we see here?