NCLE Basic Exam Kit Questions With Verified Answers

What is the Secondary/intermediate curve? - Answer The curve on the posterior side of the contact lense between the base curve and peripheral curve. Usually 0.7mm to 1.6mm flatter than the base curve radius. The width is affected by the OZ diameter and peripheral width. What is the peripheral curve? - Answer The outermost curve on the posterior side of the contact lens. It clears the flatter periphery and prevents lens impingement in the limbal areas What measurements effect the size of the peripheral curve? - Answer The radius of curvature and width. Smaller diameter = steeper radius of curve Larger diameter = flatter radius of curve What is a blend curve? - Answer A treatment given to sharp junctions caused by differences in radii of curvature. Mostly required between secondary and peripheral curve. Blended curve = secondary and peripheral average What is the diameter of the contact? Average diameter of an RGP lens? - Answer The overall width of lenses from end to end in mm. RGP average is 7mm to 10.5mm What is the anterior optical zone radius of curvature - Answer The radius of curvature of the front surface. It determines the refractive power of the lens. Has both a radius and diameter. How do you determine the lens power? - Answer The difference between the radio of anterior and posterior surfaces. Anterior - posterior What is the base curve? - Answer The radius of curvature of the central posterior surface of contact lenses. Measures in diopters or mm What is the OZ? - Answer The diameter of the base curve on the posterior of the contact lens in mm What is a lenticular flange? - Answer An increase or decrease in anterior edge thickness to change the lens mass or help with the positioning What is the myoflange design? - Answer An increase in anterior edge thickness that aids in better centering lenses that sit low on the cornea. Thicker = more kid interaction. The upper lid holds the lens higher What is the hyperflange or CN bevel design? - Answer A decrease in anterior edge thickness in high minus lenses to limit lid interaction. Allows lens to position more centrally on the cornea Lenticular flange steeper radius vs. flatter radius - Answer Radius between 1.5mm to 2.2mm Steeper (1.7mm) edge is too thick and lens rises high Flatter (2.2mm) edge too thin and lid control is lost About the lens edge - Answer Has 3 zones. It is the most peripheral part of the lens. The junction of posterior and anterior. Designed to limit adverse lid irritation during blinking. Helps keep posterior surface away from the cornea. Anterior zone of lens edge - Answer Part of the edge in contact with the upper lid during the blink cycle. Minimizes lid irritation during blinking Posterior zone of the lens edge - Answer Small reverse curve on the posterior surface to flare the edge away from the cornea. Allows free movement of the lens across the cornea during eye excursions and for lens removal using scissor blink technique. Also allows lens to be safely centered on cornea when it dislocates. Edge apex of the lens edge - Answer Junction between anterior and posterior zones. Must be well rounded to minimize lid awareness during blink Prism ballast - Answer Adding plastic to the anterior surface. Adds weight to the lens and gives it proper orientation of some astigmatism and bifocal designs What is the watermelon seed effect? - Answer The prism ballast takes place throughout the squeezing action of the upper lid which forces the lens downward. The more thickness let's lower lid force upward during downgaze. Happens with bifocals too. What is truncation? - Answer The removal of the inferior and/or superior parts of the lens to aid in meridional orientation and stabilization. This can be done with front toric or bifocal lenses. Spherical lens design - Answer The radius of curvature is the same in every meridian of each lens surface. The lens remains spherical even though the radius is different on each surface The front surface toric design - Answer Has a spherical posterior surface with a toric anterior curve. Usually needs a prism ballast to keep in place Back surface toric design - Answer Toric posterior curve with 2 different principle meridians 90 degrees apart. Anterior side is spherical. Controls rotation with more than 2 diopters of corneal astigmatism. Only works when refractive cylinder is 1/3 more than the corneal astigmatism because there is increased power transferred to the front of the contact. Bitoric lens design - Answer Has toric curves on both surfaces with the principle meridians 90 degrees apart. Used to improve lens position for high astigmatism. Also corrects any residual refractive component. What is K? - Answer The flattest of the primary meridians measured by keratometry Sagittal depth - Answer The distance between the central area and the flat surface on the posterior surface. Adnexa Oculi - Answer The accessory structures of the eye. Includes eyelids, eyelashes, lacrimal apparatus and conjunctiva Functions of the eyelids - Answer Distributes tears over the anterior part of the eye and limits the amount of light that enters the eye Palpebral fissure - Answer An opening formed by the eye lid margins 28-30mm horizontally by 14-15mm vertically in adults. Canthi - Answer The junctions of the upper and lower lid margins. Lateral canthus - Answer Outer canthus, forms an acute angle Medial canthus - Answer inner corner of the eye where the upper and lower eyelids meet. Rounded Caruncle - Answer Small mound of skin found at the medial canthus. Contains sweat and sebaceous glands. Appears as a yellowish elevation. Semilunar fold - Answer Lateral to the caruncle. A vestigial remnant of the third eyelid of lower animal species. Epicanthus - Answer A vertical fold of skin extending from the upper to lower lid. Can be seen in infants. Disappears with development except in Asian races where it remains and forms the almond shaped eye. Puncta - Answer An opening that drains tears from the eye about 5mm from the inner canthus along the upper and lower lid margins. Thickness of lid margins - Answer 2mm thick. Divided into inner and outer halves by the gray line What is behind and in front of the grey line? - Answer Behind are the meibomian glands and in front are the eyelashes (cilia) Sulcus - Answer The part of the eyelid that separates the orbital portion of the lid from the tarsal portion extending up to the eyebrow The 4 layers of the eyelid - Answer Skin, orbicularis oculi muscle, orbital spectrum, palpebral conjunctiva Orbicularis oculi muscle - Answer The second layer of the eyelid, a sphincter muscle that encircles the palpebral fissure and is responsible for lid closure Orbital spectrum - Answer Separates the lid from the fat contained in the orbital cavity Levator palpebrae superioris muscle - Answer Muscle that raises the eye lid. This muscle merges with the upper lid. Muscle of müller - Answer Reactor muscle in the lower lid, a smooth, involuntary muscle that contributes to lid tone. Tarsal plate - Answer Consists of firm connective tissue and gives the lid it's shape, support and firmness. 1mm thick and 25-29mm long across the lids almost from canthus to canthus. palpebral conjunctiva - Answer The fourth layer of the eyelid and innermost layer. It is a thin, transparent mucous membrane that lines the inside of the lids and sticks to the tarsus. It continues over the sclera and attaches to the limbus. The fornix - Answer The junction of the palpabral and bulbar conjunctiva. The inferior part is easily seen by pulling down the eyelid but the superior is deeper and more protected. Anything that gets lost in the eye will be confined to the anterior portion of the eye due to this. Meibomian Glands - Answer Sebaceous glands located throughout the tarsal plate and have secretion ducts that open along the eyelid margin just behind the grey line. There are 25 in the upper lid and 20 in the lower lid. They have an oily lipid secretion consisting of mostly cholesterol esters which forms the outer layer of the tear film. Glands of zeiss - Answer Modified sebaceous glands that secrete an oily substance. Located around the eyelid cilia, open into lash follicles. Glands of Moll - Answer Modified sweat glands. They secrete lipids adding to the outermost layer of the tear film Glands of Krause and Wolfring - Answer Located on the inside surface of the lids near the junction on the bulbar and palpebral conjunctiva. These are more numerous in the upper eyelids. Responsible for aqueous layer of tear film. Goblet cells - Answer Superficial glands in the conjunctiva that secrete mucous which stabilizes the tear film. Contents of the conjunctiva - Answer Blood vessels, nerves, lymphatics. At the limbus the conjunctiva epithelial cells become corneal stem cells and help regenerate the cornea epithelium Blepharitis - Answer Inflammation of the lid margins Blepharoptosis (ptosis) - Answer Dropping of upper lid Chalazion - Answer A blockage and inflammation of a meibomian gland Ectropion - Answer Outward turning of the eyelid Entropion - Answer Inward turning of the eyelid Hordeolum - Answer Infection of Zeis gland Lagophthalmos - Answer Incomplete eyelid closure Trichiasis - Answer Inward turning of the eyelashes causing the lashes to irritate the eye Skin disorders that can occur surrounding the eye - Answer Cutaneous horns, Verrucae, milia, xanthalasma Malignant tumors that can occur on the eyelid - Answer Basal cell and squamous cell carcinoma Common symptoms of conjunctival disease - Answer Abnormal secretion, discomfort, burning, itching, redness or injection of the blood vessels Chemosis of conjunctuva - Answer Swelling of conjunctiva due to smoke, smog, allergies, wind, drugs or crying and rubbing the eyes Conjunctivitis - Answer Inflammation of the conjunctiva. Can be viral, bacterial, allergic or chemical. Giant papillary conjunctivitis - Answer A specific type of conjunctivitis associated with contact lens wear. Most common in patients with coated or poorly fitted contacts. Can be identified by injection of the superior tarsal conjunctiva in association with enlarged bumps called papillae Papillae - Answer Enlarged bumps that are present on the tarsal conjunctiva of the upper lids. The eyelids must be Everted to detect this. This makes eyelid eversion an important part of every follow up exam Nevus - Answer A small pigmented benign tumor Pinguecula - Answer A small round yellowish mass of elastic degeneration of the conjunctiva that is usually located adjacent to the limbus Pterygium - Answer A wedge shaped area of elastoid degeneration of the conjunctiva that grows over the area usually from the medial bulbar conjunctiva Subconjunctival Hemorrage - Answer Blood from a ruptured conjunctival blood vessel Trachoma - Answer A viral infection producing severe scarring of the lids and eventually effecting the cornea. It is more popular in lesser developed countries and is the leading cause of blindness throughout the world What is the first refractive medium of the eye? - Answer Tears What provides oxygen to the corneal epithelial cells? - Answer Tears, oxygen is dissolved in the tears. What parts of the tears help combat ocular inflammation infection and help the anterior surface to heal? - Answer White blood cells, immunoglobulins and lysosomes What are the 5 layers of the tear film? - Answer Oily/lipid layer, aqueous layer, mucous layer, microvilli, corneal epithelium Oily/lipid layer of the tear film - Answer 0.1 micron thick, made up of oils secreted by the meibomian and Zeiss glands. This layer helps stabilize the tear film and prevents evaporation of the aqueous layer. Aqueous layer of tear film - Answer 7 micron thick. Makes up the majority of the tear film and is responsible for keeping the exposed anterior portion of the eyeball moist. Secreted by the lacrimal gland and the glans of wolfring and kraus Mucoid layer of the tear film - Answer The third layer of the tear film 0.5 micron thick. Produced by goblet cells. Main function is making the cornea wettable by providing a surface where tears spread easily. It anchors the tear film to the corneal epithelium stabilizing the tear film.