Chapter 1: Ocular Anatomy Flashcards
Visible Spectrum
ROY G BIV
(Red, Orange, yellow, Green, blue, indigo, Violet)
Red light at the longest end of the spectrum and violet light at the shorter end
Crystalline Lens
Behind the pupil
Purpose of the lenses to focus late on the retina
Anterior chamber
Volume between the cornea and iris
Hyperopia
Farsightedness occurs if I is too short or the curve of the cornea is too flat causing light rays to focus behind the retina
Correct w/ (+) lenses
Rods
- Highly sensitive to light and there are about 120 million rods contained within the retina
- Suited for night vision and peripheral vision
Antimetropia
An extreme case of anisometropia where one eye is Myropic and the other is hyperopic
Vitreous humor
-Vitreous chamber is filled with a thicker gel like substance -maintains the shape of the eye
Refraction
- As light moves from one transparent medium to another at any angle other than perpendicular to the material surface the change in speed will also result in a change in direction
- allows the creation of optical lenses that alter the path or focus of light
Inferior Oblique
Moves the eye outward and upward
Prentice’s Rule
States that prism in diopters 🔼 is equal to decentration distance in centimeters multiplied by the lens power
Dilator Muscle
- Iris muscle
- Opens the pupil allowing more light into the eye
Emmetropia
An eye free of refractive errors
Diplopia
-difficulty w/ fusion can cause double vision or cause the brain to “turn off” one image in an effort to eliminate diplopia
Suppression
The later is known as this condition
Presbyopia
Condition where the crystalline lens is unable to add sufficient power to focus at near
Correct w/ (+) lens, reading glasses or magnifying devices
Sphincter Muscle
Closes the pupil, restricting light into the eye
Amblyopia
Lazy eye
The brain will often suppress the vision of the blurrier eye in this condition
Accommodation
Process of focusing on objects based on their distance
Anisometropia
A condition in which the two eyes have unequal refraction power
(Same + or -)
Prism
Can be used to correct vision for an individual whose eyes are not perfectly aligned
Wavelength
The distance between two corresponding points on two consecutive waves
Tropia
When the eye has a definite or obvious training from its normal position
Phoria
- When the eye has a tendency to turn from its normal position
- EX: when patient is tired
Medial rectus
Moves I inward towards the nose
Myopia
Nearsightedness occurs if the eye is longer than normal or The curve of the cornea is too steep causing light rays to focus in front of the retina
Correct w/ (-) lenses
360 or 180 Method
-When a lens is viewed from the front, a prism w/ a base direction to the right becomes
O: (base in for the right eye, base out for the left eye)
- labs use this method for describing base direction
Prescribers method
Specifics the direction if the prism in terms of the base using base-up base-down bass-in and base-out
Fovea
Center of the retina
Strabismus
- Eyes are not aligned the right and left see different images resulting in blurred and double vision
- Sometimes the brain can shut off when I attempt to remedy the vision resulting in molecular vision and loss of depth perception
Vitreous Chamber
The greatest volume forming about 4/5 of the eye is found between the retina and lens
Stroma
- Middle layer of the cornea between the two membranes
- makes up 90% of the thickness of the cornea
Aqueous humor
- Both chambers contain this fluid
- Watery fluid produced by the ciliary body
Inferior rectus
Moves the eye downward and slightly inward
Posterior chamber
Volume between the iris and the lens
Cones
- Primary function of detail and color detection
- 6 million cones within the retina
Astigmatism
Occurs when the cornea has an oblong football like sheep in one or more directions causing light rays to focus on more than one point on the retina
(Correct w/ Cyl Power on Correct Axis
Superior oblique
Moves that Eye upward and downward
Superior rectus
Moster Eye upward and slightly outward
Lateral rectus
Moves that Eye outward and away from the nose
