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BVC NCLE STUDY
Study guide for NCLE testing
Question | Answer |
---|---|
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 |