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RX +11.00+1.00x020 VD=12mm K: 46.25/47.25; What's the power of RGP lens fitted on K
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A -3.50 lens with a BC of 44.50D provides excellent visual acuity. If the CPC were changed to 45.00D what power would be needed
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BVC NCLE STUDY

Study guide for NCLE testing

QuestionAnswer
RX +11.00+1.00x020 VD=12mm K: 46.25/47.25; What's the power of RGP lens fitted on K NCLE will say +13.00D, but +13.00D, +13.25, and +13.50D are all correct
A -3.50 lens with a BC of 44.50D provides excellent visual acuity. If the CPC were changed to 45.00D what power would be needed Minus -3.00 (LLP= -0.50)
A composite of secretions from lacrimal glands, accessory glands of krau and wolfring, mucin secreting goblet of the conjunctiva, melbomian secreting tarsal glands and oil secreting glands of this Precorneal tear film
A condition where the iris or portions of the iris is absent is called Aniridia
A contact lens contains 2 curves; one BC and one secondary curve Bicurve contact lens
A contact lens designed with a peripheral carrier or flange having no power and a central power zone is called a ____ contact lens Lenticular design
A contact lens has a BC of 7.50mm, what would the PPC most likely be? 7.45mm, 42.50D, 7.35mm, 30.00D 30.00 = 11.25mm; SSS rule
A contact lens having a BC radius of 7.94mm fits too tightly, a tighter fitting contact lens will have which one o the following BC; 7.99 or 7.85 7.85mm
A contact lens having an overall diameter of 9.5mm fits too tightly, a looser contact lens will have which diameter; 9.6 or 9.3 9.3mm
A contact lens in which the anterior surface contains two different radii of curvature and the posterior surface is spherical curve is called Front surface toric
A gradual lessening of the power of accomodation due to a physiologic change that becomes noticeable about the age of 40 years Presbyopia
A high minus RGP contact lens should have (+ / -) carrier lenitcular lenses Plus carrier lenticular lens, hyperflange
A high minus rigid gas permeable lens will be thin centrally with relatively thick edges. To reduce the edge thickness, and increase overal comfort, use A hyperflange
A lab measurement of the oxygen permeability of a RGP contact lens is called DK value
A large different between the amount of correction between OD and OS, difference of 2.00 diopters or more between the refractive errors of the eyes Anisometropia
A layer of condensed stromal tissue that seperates the epithelium from the stroma Bowman's Layers
A lens design generally used in higher plus powers which consists of a central optic zone and a surrounding non-optic peripheral or carrier portion is Lenticular bowl
A lens in which both the posterior surface has two different radii and the anterior surface has two different radii is Bi-toric
A lens in which the anterior surface has two different radii and the posterior surface is spherical Front surface toric lenses
A lens may behave like a tight lens even if the fit is good because Blinking is infrequent and the lens dries and shrinks. Also if the lens is overworn and not replaced
A refractive error that prevents light rays from coming to a single focus on the retina because of different degrees of refraction in a various meridians of the eye Astigmatism
A soft contact lens case should be thoroughly cleaned at least Once per week
A soft contact lens demonstrates excessive movement. This can be fixed with a lens that has a ____ diameter Larger diameter; larger diameter = steeper fit = tighter fit
A spherical PMMA contact lens should be fit so that there is a slight Apical clearance
A term sometimes used to mean congestion of the ciliary or conjunctiva blood vessels, redness of the eye Infections (scleral…conjunctival)
A test used to assess the quality of the precorneal tear film is called the B.U.T. Test (Break-up Time)
A tightly fitted soft contact lens can cause Corneal edema, limbal compression
A truncation is used on a rigid gas permeable contact lenses to help enhance the performance of which type of design Bifocal
Abrasion Rubbing off of the superficial layer
Abbreviation for an RDP material which combines silicon or oxygen. Transmissibility and mentacrylae for optical quality, lenses machinability and stability Silicone Acrylate
Against-the-rule-astigmatism A condition in which the steepest corneal median is in the horizontal plane (example: K's 45.00@180/42.00@090
Air bubbles in the center of the lens mean BC is too steep or diameter is too large
Albinism Hereditary loss of pigment in the eye, skin and hair, usually associated with lowered visual acuity, nystagmus and light sensitivity
Also called giant papillary hypertopia, GPH a condition associated with contact lens wear, especially sot lens wear, marked by increasing lens awareness, itching, mucus discharge, formation of a coating on the lens GPC; giant papillary conjunctivitis
Amblyopia (lazy eye) Loss of vision without any apparent disease of the eye
Amblyopia ex anopsia Loss of vision due to disuse of the eye, usually due to uncorrected refractive errors
Ametropia A refractive error in which the eye, when in a state of rest, does not focus the image of an object upon the retina; includes hypertopia, myopia and astigmatism
An acute infection of the Meibomian glands is called An internal Hordeolum
An enzyme contained in the precorneal tear fill that protects the cornea from infections is Lysozyme
An eye spectacle RX od -4.00+1.00x180, this eye should be fit with a hydrogel contact lens having a power of (1/3 rule) -3.50D
An eye spectacle RX of -3.00-0.25x180. This eye should be fit with a soft contact lens having a power of (1/3 rule) -3.00D
Aniseikonia A condition in which the ocular image of an object as seen by one eye differs so much size or shape from that seen by the other eye that the two images cannot be fused into a single impression
Anisocoria Inequality of the pupils in diameter
Anomaly Departure from the normal
Anopthalmia Absence of a true eyeball
Anterior Chamber Space in front of the eye, bounded in front by the cornea and behind by the iris; filled with aqueous humor
Antibody A specific substance produced by the body in the presence of an antigen
Antigen Any substance that when introduced in the body incites formation of an antibody
Antihistamines Substance that acts against the action of histamine
Aphakia Absence of the crystalline lens of the eye
Aqueous humor Clear, watery fluid that fills the anterior and posterior chambers within the front part of the eye
Arcus Senilis Grayish white ring in the periphery of the cornea
Bedewing (watery eye) An edematous condition of the epithelium of the cornea characterized by irregular reflection from the multitude of droplets when the cornea is viewed with the slit lamp
Biconcave Lens Lens having a concave surface on both faces
Biconvex Lens Lens having a convex surface on both faces
Binocular Vision Ability to use the two eyes simultaneously to focus on the same object and to fuse the two images into a single image that gives a correct interpretation of its solidity and its position in space
Blepharitis Inflammation of the margins of the eyelids
Blepharochalasis Excessive relaxation of eyelid skin due to loss of elasticity
Blepharoconjunctivitis Inflammation of the eyelid and conjunctiva
Blepharoplasty Plastic surgery of the eyelid
Blepharoptosis Drooping of the upper eyelid
Blepharospasm Excessive winking; tonic or clonic spasm of the orbicular is oculi muscle
Cataract Operative Procedures Surgical procedures to remove the opaque lens. They include intracapsular and extracapsular procedures, linear extraction, cataract needling, discussion, and aspiration
Caved in surface curvature; having the power to diverge light rays, denoted by a minus sing Concave
Central clearance between the cornea apex and the posterior surface of a contact lens. As a contact lens steepens the sagital depth increases period as a contact lens flattens the sagital depth decreases Sagital dept
Central Visual Acuity Ability of the eye to perceive in the direct line of vision
Chalazion Inflammatory enlargement of a meibomian gland of the eyelid
Chemosis Severe edema of the conjunctiva
Choiroiditis Congenital cleft due to the failure of the eye to complete growth in the part affected
Choriorentintis Inflammation of the choroid
Choroid Portion of the vascular coat between the iris and the choroid; consists of ciliary processes and the ciliary muscle
Ciliary Body Diminished ability to perceive difference color. This is usually true for reds and greens, rarely for blues and yellows
Congenital absence of the iris Aniridia
Conjunctiva "Glasses" so constructed that they fit directly on the eyeball under the eyelids
Conjunctivitis Process of directing the visual axes of the two eyes to a near point, with the result that the pupils of the two eyes are closer together
Contact lenses A lens having the power to converge rays of light and to bring them to a focus; also known as converging, magnifying hyperopic, or plus lens. These lenses are denoted by the "+" sign
Contains sweat and sebaceous glands Caruncle
Controls the amount of light to enter the eye Eyelids
Cornea Clear, transparent portion of the outer coat of the eyeball, forming the covering of the aqueous chamber. The ____ is responsible for the majority of the eye's refractive ability
Corneal graft Operations to restored vision by replacing a section of opaque cornea
Corneal layer separating the stroma from the endothelium Descemet's layer
Corneal layer underlining the Bowman's membrane composed of dense strata of collagen fiber laid down in a rectangle manner. The stroma comprises about 90% of the cornea thickness. Then damaged the layers heals without the formation of scar tissue Stroma
Diameter of the base curve is referred to as Optic zone (OZ)
Dimple veil staining on the cornea is caused by Air bubbles trapped under a rigid lens
Distortion, the failure of rays to converge at one focus because of limitations or defects in a lens Aberration
Distributes tears across the outer surface Eyelids
During a blink the lower eyelid moves primarily towards the Nose
Expressed diopters of surface power 42.75D
First line of defense in eyeball protections Lashes
For every ____D change in power the back curve is different .25D
For successful contact lens wear, EOP should be at least 7%
Front surface Anterior
How do we correct a lens that is too tight Smaller diameter, and flatter base curve
How do we correct a lens that’s too loose Make sure the lens is not inside out, needs a larger diameter or steeper base curve
How do we FOG the patient Refraction refinement technique; a lens is placed in front of the eye to blur VA and relax accommodation. Over plus the patient so vision is blurry, start with a +1.50 to FOG. Immediately hold the correct power in front of the patients eye and check VA
How do you assess the quality of the peripheral curves of a RGP lens using a Shadowgraph
How long does a lens need to equilibrate for before evaluation the fit 20 minutes; lens becomes hydrated with patients tears and reaches temp of 98.6
How many layers does the cornea have 5 layers
How much light does a handling/visibility tint absorb 10%
How much light does an enhancement tine absorb 10-20%
Hydrogel contact lens are made of what material HEMA
Hydrogel lenses with low water content Needs fewer tears to stay hydrated, easier to handle because they are softer and more flexible, they attract more deposits which reduce oxygen, need more tears to stay hydrated
If visual acuity is blurry throughout the blink cycle the problem is probably with the Power
Important in lubrication due to surrounding sebaceous glands Lashes
In order to steepen the base curve of a rigid gas permeable lens without changing the lens cornea relationship, you would also need to Decrease the optical zone diameter
In order to tighten the fit of a rigid gas permeable lens, you can Increase the optical zone diameter, increase the overall lens diameter
In which of the following situations is a rigid gas permeable lens always preferred over a soft lens Irregular astigmatism
Increasing the overall diameter of a contact lens makes the lens steeper or flatter Steeper
Inflammation of lid margin Blepharitis
Inflammation of the cornea, frequently classified as the type of inflammation and layer of the cornea affected Keratisis
Inflammation of the margin of the eyelid Belpharitis
Innermost tear film layer responsible for adhering the tear film to the anterior surface of the cornea produced by the goblet cells of the conjunctiva Mucin/Mucoid/Mucus layer
Lowers the lid Contractor muscle
Maintains shape of lids Muscle of the Muller
Manufacturers of newer lenses suggest that they move how much .5mm - 1.0mm
Millimeter ruler used to measure the overall diameter of a rigid lens as an alternative to hand magnifier Diameter V gauge
mm of radius of curvature 7.90mm
Modified cilia Lashes
Most visible outer structure of the eye Eyelids
Muscle responsible for the lid closure Orbicularis oculi
Multilayered organ Eyelids
Myopes are under or cover corrected with fogging Under
Outermost tear film layer produces by the Melbournian gland in the upper tarsal that prevents or delays tear evaporation Lipid layer
Overall diameter, total diameter. The chord length of a lens, measured across the back surface from edge to edge Diameter
Palbebral Eyelids
People with steep corneas have a smaller or larger HVID Smaller
Poly methyl methacrylate which lens material, the original hard lens, non-oxygen permeable durable excellent optics PMMA
Polymegathism of the corneal endothelium is thought to be due too Corneal hypoxia
Preservatives in contact lens solutions can cause Photophobia, corneal staining, excess tearing
Primary colors Two kinds of cells that form a layer of retina and act as light-receiving media. ____ are concerned with visual acuity and color discrimination; ____ are employed for motion and vision at low degrees of illumination
Process of renewal or restoration in the cornea certain layers regenerate Regenerate corneal tissue
Raises the upper lid Levator palpebral seperioris
Sensitive to touch warning when something approaches the eye and causes to close Lashes
Severe damage to the corneal endothelium results in what VD doesn’t matter since RX is less than 4.00, -3.50D
Shortening the BC radius of a contact lens makes the lens steeper or flatter Steeper
Spectacle lens prescribed at -10.00D, if the lens fit is at a vertex distance of 10mm, an RGP contact lens fit on K will required a power of how much Minus 9.00 lens; coming closer gains power
Surrounds a hill of sin called Caruncle Nasal Canthus, medical Canthus, inner Canthus
Tear film break up time; the time it takes for dry spots to form on the cornea when the eye is kept in the steering position. Normal range is 10-30 seconds, less than 10 seconds indicates a level of dry eye B.U.T. Test (Break-up Time)
Tears drain into the Punctum
The astigmatism present after corneal astigmatism has been neutralized by a contact lens. It is the astigmatism created by the crystalline lens of the eye Residual astigmatism
The average central thickness of the cornea is 0.56mm
The base curve of a contact lens is also known as the Central Posterior Curve (CPC)
The CPC of a contact lens measures 7.5mm radius, how much is the power in diopters 45.00D
The CPC of a trial contact lens is 44.00D and contains a power equal to +14.87D. The over refraction is equal to -1.62D. What is the final contact lens RX if the CPC to be ordered is 43.62D Plus 13.63 (LLP= +0.38D)
The curvature of the central part of the posterior surface of a contact lens. Base curves is expressed in millimeters of radius of curvature or in diopters. Also referred as central posterior curve. Base curve (BC)
The curvature of the central portion of the back surface of a contact lens is the Base curve (BC)
The Descemet's membrane of the cornea is produced by which layer of the cornea Endothelium
The diameter of a lens must be large enough To cover the cornea, vault the limbus and extend over the limbus 1mm all the way around
The distance between a flat surface and the back surface of the central portion of a lens is called the Sagital depth (vault, height)
The effective power of a contact lens measured from the back surface is the Back vertex power (BVP)
The effective power of a lens when measured from the back surface Back vertex power (BVP)
The function of the eyelids are Limit the amount of light entering the eye, protect the eye from external irritation, distribute tears over the surface of the eye
The lipid layer of the precorneal tear film is secreted from the Meibomian glands
The main disadvantage of soft contact lenses Protein deposits
The mass of an aphakic rigid gas permeable contact lens can reduced by making the lens design Lenticular
The measurement from one edge of a contact lens to the opposite edge is the Chord diameter
The measurement from one edge of the lens to the opposite edge is Chord diameter
The Meibomian glands are located on the Tarsal plate
The muscle responsible for elevation of the upper eyelid is the Levator palpebrae
The mucus layer of the precorneal tear film is secreted by the Conjunctival goblet cells
The newest corneal layer discovered between the stroma and the Descemet's membrane. The toughest layer can resist pressure damage between 700-900mm HG Dua's Layer
The opening of the Meibomian glands are found on the Eyelid margin
Created by: misz.corcor
 

 



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