ABO sample Questions & Answers(Verified) When light is refraction by a prism it is: a. Bent toward the apex b, Bent toward the base c. Not bent d. Reflected - ANSWER B. Bent toward the base A prism always bends light toward its base. Prisms: I. Always

ABO sample Questions & Answers(Verified) When light is refraction by a prism it is: a. Bent toward the apex b, Bent toward the base c. Not bent d. Reflected - ANSWER B. Bent toward the base A prism always bends light toward its base. Prisms: I. Always bend light toward the base II. Always bend light toward the apex III. Cause chromatic Dispersion IV. Move the image toward the apex V. Are sometimes prescribed for muscle problems - ANSWER I. Always bend light toward base III. Cause chromatic dispersion. IV. Move the image toward the apex. V. are sometimes prescribed for muscle problems Plus lenses are: I. are thicker in the center than at the edges II. Are used to correct myopia III. Are used by all presbyopes IV. Must be surfaced individually in the laboratory - ANSWER I. Are thicker in the center than at the edges. Which of the following does not describe a minus lens a, The image moves with motion b. Thicker at the edge than in the center c. Magnifies the image d. Corrects for myopia - ANSWER c. A minus lens minifies, not maginfies The parts of the eye that refract light are: a. Cornea, Aqueous humor, lens and vitreous humor b. Cornea, Iris, and lens c.Retina, choriod, lens, and aqueous humor d. cornea, lens, and pupil - ANSWER A. Cornea, Aqueous humor, lens and vitreous humor. Where the sclera and the cornea meet is called the a. Iris b. Limbus c. Ora serrata d. conjunctiva - ANSWER B. Limbus A cataract is: a. A film over the eye b. a cloudiness of the crystalline lens c. removal of the crystalline lens d. an internal ptergium - ANSWER b. A cloudiness of the crystalline lens A cataract may also be referred to as opacification of the lens. removal or absence of the crystalline lens is aphakia Near visual acuity is often abbreviated as: a. 20/40 b. 10/10 c. N. 15 d. J.2 - ANSWER D. J.2 Distance visual acuity usually has two numbers. It is a comparison of the distance a patient is from the target to what an average person can see at that distance. One of the most common tests for visual acuity is the Jaeger test Card. The results are signified by the letter J with a number. Myopia can be attributed to a. Loss of accommodation. b a shorter than normal eyeball c. a longer than normal eyeball d. astigmatism - ANSWER C. a longer than normal eyeball Myopia is a condition of distance vision. It is caused by the refracting system of the eye having too much plus power for length, or the eye being too long for its power. Eyeglasses can relieve or correct all of the following conditions except: a. A scotoma b. Presbyopia c. Simple astigmatism d. Mixed astigmatism - ANSWER a. A scotoma A scotoma is a "blind spot" of the retina. no glasses can correct it. The condition known as second sight is often associated with: a. increase in accommodation b. incipient cataract c. ocular rejuvenation d. surgery - ANSWER b. Incipient cataract. Some presbyopes find they no longer need glasses to read. This so called "Second sight" is usually caused by an increase in myopia due to swelling of the crystalline lens caused by a developing cataract. A aphakic patient is more sensitive to light because a. the filtering action of the crystalline lens is no longer present b. cataract surgery often results in ptosis c. of the age of the patient d. proper fitting reduces vertex power. - ANSWER A. the filtering action of the crystalline lens is no longer present A Crystalline lens is a very effect filter for ultraviolet light, and as the patient gets older visible light at the short end of the spectrum (especially blue). When the lens is removed (cataract surgery) the person is often very sensitive to light. A ptosis or drooping of the lid is often present after surgery, but this will only reduce the amount of light entering the eye. With new glasses, a patient complains that things appear smaller. this could be caused by a. increase in plus power b. increase in minus power c. decrease in minus power d. astigmatism is uncorrected - ANSWER b. Increase in minus power minus lenses minify the image (make things smaller) A person with diplopia: a. sees only one half of an object b. sees two objects c. sees objects divided d. has low visual acuity - ANSWER b. Sees two objects Di=two; diplopia= double vision OD +2.00 +.50 x 90 OS +0.50 +0.25 x85 The above prescription illustrates a case of: a. Presbyopia b. anisometropia c. antimetropia d. simple myopic astigmatism - ANSWER B. Anisometropia an-(not) iso-(equal) opia (vision)= unequal vision or prescribtion Minus lenses: I. Correct for myopia II. show against motion when moved III. Show with motion when moved IV. Are thinner at the center than at the edge - ANSWER I. Correct for myopia III. Show WITH motion when moved IV. Are thinner at the center than at the edge Decentering a minus lens downward will cause: a. A change in power b. Base up prism c. Base down prism d. A change in PD - ANSWER B. Base up prism remember the rules: Plus lenses: base orientation of prism is the same as the direction of decentration minus lenses: Base orientation is the opposite of the direction of the decentration A patient complains of the floor tilting away from him when he puts on his new glasses. This is probably caused by: a. an increase in plus power b. an increase in minus power c. a reduction in plus power d. a change in cylinder power - ANSWER A. an increase in plus power In this case the lens remains fixed while the eye looks down. Prism causes a displacement of images toward the apex. If the floor now appears to tilt away from him, we can assume a base up prism. Base up effect (relative to what he was used to) comes from increased plus or decreased minus power. In what quadrant would the base of the resultant prism occur in the following prescription OD: Plano sph 2BU&2BO a. Upper temporal b. lower temporal c. upper nasal d. lower nasal - ANSWER A. Upper temporal Up and out is the same as upper temporal. If the question referes to the lensometer target picute the patient is facing you and wearing the glasses. use this as a reference for directions The color usually recommended for shooting glasses is: a. G-15 Green b. Kalichrome yellow c. Polaroid gray d. brown gradient - ANSWER b. kalichrome yellow Yellow is color recommended for shooting glasses. It contrasts the most. Safety experts say the best color for night driving is: a. Yellow b. grey c. green d. no color - ANSWER d. No color Photophobia can be relieved by all of the following except. a. grey lenses b. yellow lenses c. brown lenses d. green lenses - ANSWER b. Yellow lenses photophobia is an abnormal intolerance of light. Yellow lenses cut out very little light in the most sensitive part of the visible spectrum. The refractive error where rays of light focus in front of the retina is: a. presbyopia a c. hyperopia d. emmetropia - ANSWER b. myopia Presbyopia and hyperopia require plus power. emmetropia is normal vision (no refractive error). Light coming to a focus of the retina indicates too much plus power, or myopia. The instrument that can help you determine if a glass lens was heat tempered is: a. A miocroscope b. A radiuscope c. A vertometer d. A polariscope - ANSWER D. Polariscope A polariscope (sometimes called a colmascope) is used to check the strain pattern caused when a lens is air tempered (sometimes called case hardening) it is made from two polariod lenses placed between their polarizing axes at right angles to each other. if a lens with strain is placed between them, a light pattern appears. a typical question might also ask if one lens was dislodged, how should it be replaced in the polariscope. the answer would be 90 degrees apart. Vertical imbalance in a pair of glasses can best be determined by use of: a. the reticle of a lensometer b. the power drum of a lensometer c. a digital spectometer d. calipers and a lens clock - ANSWER a. the Reticle of a lensometer sometimes "knowing too much" can hurt you on a test. There are other methods of determining prism (knowing the power and comparing top and bottom thickness) Use the easiest and most obvious choice- the reticle of the lensometer is marked in circles of prism. If you center the target in the reticle while looking through the near portion of a biofocal lens, you have located the: a. Distance optical center b. Segment optical center c. resultant optical center d. reading level - ANSWER C. Resultant optical center. If the target is centered on the reticle, you have located a spot with no prism, an optical center. The distance O.C is obviously in the distance portion of the lens. The true optical center of the segment can be only determined in a lensometer if the distance has no power. looking through the lower portion of the lens (below the distance optical center) some prism is induced. since you are looking through a segment which has been "added to" the distance portion, there is some prism present. you have therefore, located not the segment optical center but the resultant optical center- your reading is a result of the prism being induced by the distance portion of the lens. If the power drum of a vertometer reads +1.25 for the sphere lines and -2.25 for the cylinder lines, axis 90, the power of the lens is: a. +1.25 -1.25 x 90 b. +1.25 -3.50 x 90 c. -2.25 +1.25 x90 d. +1.25 -1.00 x 90 - ANSWER B. +1.25 -3.50 x 90 The power of a cylinder is the distance moved from the first, or sphere reading. Going from +1.25 it is 1.25D to plano, and another 2.25D to -2.25 or a total of 3.5 diopters. As you were moving in a minus direction, the cylinder is -3.50. The choice of answers might include the answer in a transposed form, but there will only be one correct answer. Glass lenses for standard use must withstand: a. a 1" steel ball dropped from a height of 24" b. a 5/8 " steel ball dropped from a height of 24" c. a 1" steel ball dropped from a height of 50" d. a 5/8" steel ball dropped from a height of 50" - ANSWER D. a 5/8" steel ball dropped from a height of 50" The best instrument to check vertex distance is: a. Calipers b. a distometer c. a PD rule d. a lensometer - ANSWER b. Vertex distance is best checked by the use of a distometer. Note that 1mm should be added for eyelid thickness. Other instrumentation questions might refer to lens measures (clocks) and use of calipers to measure thickness. They are calibrated in 1/5 mm (called points) A first time bifocal wearer is a draftsman. What type of bifocal would you recommend I. A kryptok II. A flat top 28 III. A flat top 45. IV. An executive V. Blended segment - ANSWER III. Flat top 45 IV an executive The key words here are "first time wearer" and "draftsman" While we sometimes hesitate to change the bifocal style of a previous wearer, we should always try to give the new wearer the most suitable lens. A drafts person needs a wide segment for work. A frame bridge that is designed to rest only on the sides of the nose is: a. A saddle bridge b. A keyhole bridge c. a formfit bridge d. an inset bridge - ANSWER B. A keyhole bridge Both a saddle and formfit bridges generally rest on a wide area of the nose. An inset bridge is meant to increase the vertex distance for flat noses. A keyhole has a cut-out top and thus usually does not rest on the top of the bridge A patient is wearing a temple marked a 5 1/2". The closest metric size that should be ordered for replacement is: a. 5 1/4" b. 135 mm c. 140mm d. 145 mm - ANSWER C. 140mm IF you are mathematical, there are 25.4 mm in an inch. Otherwise look at your PD ruler. 5 1/2" and 140mm nearly match. Add or subtract 1/4" for each 5mm. Diagram 1 - ANSWER Diagram 1 Diagram 2 - ANSWER Diagram 2 The segment height of a finished biofocal lens is measured from: a. the top of the seg to the edge of the eyewire b. the top of the seg to the deepest part of the lens c. the lower lid to the bottom of the eyewire b. the center of the seg to the edge immediately below - ANSWER b. The top of the seg to the deepest part of the lens The language is important here. Segment height is measured from the seg to the lowest part of the lens. The question also refers to a FINISHED bifocal lens. OD: -7.25 -1.75 x 180 OS -850 sph Use the following will improve the appearance of the job: I. Higher index material such as polycarbonate II. Steeper base curves III. Use of a frame with a smaller ED IV. Use of a frame that requires less decentration - ANSWER I. Higher index material such as polycarbonate III Use of a frame with a smaller ED IV Use of a frame that requires less decentration The obvious improvable problem is lens thickness. Higher index of refraction reduces lens thickness as does smaller lens size (smaller ED and less decentration) OD: -7.25 -1.75 x 180 OS -850 sph Use of the following might reduce the high minus appearance: I. Hide a Bevel II. Edge coating III. A thicker eyewire IV. a nylon suspension mounting - ANSWER I,Hide a bevel II. Edge coating III. A thicker eyewire Hide a bevel and edge coating reduce the "ring effect" A thicker eyewire makes the edge less visible from certain angles. Rx +10.00 +2.00 x 90 Refracted vertex distance is 15mm. If this RX is to be fitted at 10mmm, the RX to be ordered is: a. +9.75 +2.25 x 90 b. +10.00 +2.00 x 90 c. +11.00 sph d. +10.50 +2.25 x 90 - ANSWER d. +10.50 +2.25 x 90 If you can fit a strong lens closer than the doctor refracted you should do so and compensate for the change in effective power. Remember CAP- Closer add plus. Also remember that the power will usually change. In this case, only one choice was both more plus and had a cylinder change. RX -12.00 sph Refracted vertex distance is 12mm. If this lens was moved to a vertex distance of 14mm, the effective power of this lens would now be: a. -11.75 b. -12.00 c. -12.25 d. -12.75 - ANSWER a. -11.75 Here they ask for EFFECTIVE power. not what compensated lens power should be ordered. Remember if closer- add plus. If further ass minus. If a stronger minus should be ordered then the effective power of the original lens has been reduced. only one choice is less minus. Of the following prescriptions, which would you question the validity of and call the refractionist for verification. a. O.U plano sph 2BI b. OD: +1.00 sph OS: +.50 sph 1BU c. OD: +2.00 sph 2BI&BU OS: +2.25 2BI&2BU d. OD: -1.00 sph 1BD&2BO OS: -.25 sph 1BU&2BO - ANSWER C. OD: +2.00 sph 2BI&BU OS: +2.25 2BI&2BU Prism prescribed base up in one eye is the equivalent to base down in the other eye. Both lenses can share either Base in or Base out. In answer C. Both eyes were given base up. This is highly unusual, and should be verified by the doctor. A mistake was probably made in transcribing the prescription. Rx: OD: -4.50sph 4BU OS: -4.00 2BI which of the following is a usually acceptable method of improving appearances: a. OD: -4.50 sph OS: -4.00 sph 4BU&BI b. OD: -4.50 Sph 2BU OS: -4.00 sph 2BD&2BI c. OU: -4.25 2BU&2BI d. OD; -4.50 sph 2BU OS: -4.00 Sph 2BU&2BI - ANSWER b. OD: -4.50 Sph 2BU OS: -4.00 sph 2BD&2BI The doctor will almost always be willing to split the prism to balance the thickness of the two lenses. This would be especially helpful for the right eye in this case, where 4BU would result in great edge thickness at the top of the right lens. This could even affect the ability to fit the glasses correctly Which of the following is usually the most satisfactory bridge for children a. Saddle b. keyhole c. Adjustable pads d. brooklyn - ANSWER A. Saddle The most satisfactory bridge for children is the one that will rest on the most area of the nose. A saddle bridge usually does so on a child's flatter bridge. Pad arms pose a potential danger. In trying a new frame on, you find that a particular frame fits a patient well, but the frame sits too high. You should select another frame with a bridge that is: a. wider b. narrower c. higher d. lower - ANSWER c. higher The key part of the question stated that the bridge fit well. Therefore do not give one wider or narrower. A higher bridge will enable the bridge to fit lower. Most fused bifocals now use the following type of glass for the segments to reduce chromatic problems a. Flint b. titanium c. Barium d. crown - ANSWER c. Barium Barium and its relative baryta is most commonly used segment glass Distortion in strong plus lenses (above +8.00) can be reduced by the use of: a. Asphericity b. corrected curves c. proper tilt d. MED fitting - ANSWER a. Asphericity Aspericity is the most effective way to reduce distortion. Lenses above +8.00 do not greatly benefit from corrected curves. The other choices have only slight validity The norminal power of a 2x hand held magnifier is: a. 2 diopters b. 4 diopters c. 8 diopters d. 20 diopters - ANSWER c. 8 diopters 2x is 2 power. The rule of thumb is 4 diopters per x. 2x is therefore 2x4 =8 The reflection off the cornea usually coincides with: a. the optical axis of the lens b. the visual axis of the eye c. the top of the segment d. the geometric center of the lens - ANSWER B. the visual axis of the eye The corneal reflection such as that used in a pupillometer measures a point that closely coincides with the visual axis of the eye. Visual axis and line of sight are basically the same. Rx: OD: +12.00 -1.00 x 175 OS: Balance What is the most suitable lens to use for the left eye a. plano sph b. plano -1.00 x 75 c. +10.00 sph d. +11.50 sph - ANSWER d. +11.50 sph When a balance lenses are prescribed, the doctor generally wants a lens that is close to the other lens in power, thickness and appearance. As the usually more expensive compound of is not needed. a sphere equivalent is recommended. This is equal to the average power of the prescribed lens. The formula for calculating sphere equivalent is to add 50% of the total cylinder power to the sphere power. Rx: OD: +10.00 sph OS: +11.25 -.75 x 180 OU: +2.00 Which of the following bifocals is least suitable for this Rx: a. flat-top 24. b. Plastic 22 round c. Executive d. Plastic flat top - 28 - ANSWER c. Executive RX: OD +12.25 -.50 x 165 OS: Balance This patient is a right unilateral aphakic. You would expect this patient to: a. Have good binocular vision b. have good vision only for the right eye with glasses. c. use glasses for both distance and near d. Have had an intraocular implant in the right eye. - ANSWER b. Have good vision only for the right eye with glasses A balance lens is prescribed for a unilateral aphakic to block vision on the unoperated eye, as the differences in image sizes with two vastly different lenses make binocular vision impossible. Aphakics have also lost the power to accommodate, and require either bifocals or seperate glasses for near. Rx; OD: +11.50 -1.00 x 90 OS: +10.75 -.50 x85 Add: +2.50 OU P.D- 66/62 Full Field aspheric (such as a multi-drop) Which of the following frames is not suitable for this job a, Shuron Nusir 46x37 20DBL b. Country Squire 48x40 20DBL c. Delegate 48x39 20 DBL d. Sprint goggle 58x51 15 DBL - ANSWER D. Sprint goggle 58x51 15DBL Full field aspheric cataract lens should be fit in symmetrical frames of moderate sied so that the minimum blank size is kept as small as possible. the question might also ask which of the following is unavailable. they are trying to demonstrate that the increased thickness caused by a frame such as the goggle mentioned would make the lenses unavailable due to the extreme black thickness required. Rx; OD: +11.50 -1.00 x 90 OS: +10.75 -.50 x85 Add: +2.50 OU P.D- 66/62 Patient is aphakic. He wants seperate pair of sunglasses just for golf. Which of the following would be suitable. a. a trifocal b. a low fitting flat top c. Single vision with the patient informed to slide them down his nose to see at near d. a round seg bifocal fit high with instrutions to look over the top of the seg. - ANSWER C. Single vision with the patient informed to slide them down his nose to see at near. They seem to love golfing questions. golfers need an unobstructed distance field of vision. A high segment and a trifocal are inappropriate. Aberrations in cataract lenses increase greatly as we move away from center, thus a low sef and again trifocal are inappropriate. The golder only needs near to fill out his scorecard and sliding glasses down his nose would give him the additional plus power and magnification necessary to see the card. RX. -3.00 sph OU Safety glasses The minimum thickness of the lenses must be a. 2mm b. 2.2 mm c. 3mm d. 3.5mm - ANSWER C. 3mm Safety glasses must be a minimum of 3mm thick(some plus lenses can be 2.5 mm at the edge) They must also meet a penetration by a weighted needle done by some lens manufacturer to randomly select a few lenses from each batch. The most commonly used plastic frame material for safety eyewear is: a. Epoxy resins b. PMMA c. Cellulose acetate d. Cellulose nitrate - ANSWER c. Cellulose acetate Plastic safety frames must be fire retardant. PMMA (acrylic) and epoxy (optyl) break with rather sharp edges. Cellulose nitrate is no longer used in the USA because it is highly flammable. Safety lenses must withstand a. a 1" ball dropped from 50" b. a 5/8" ball dropped from 50" c. a 7/8" ball dropped from 1 meter d. there is no drop ball requirement - ANSWER a. A 1" ball dropped from 1" Safety lenses must each be drop ball tested with a 1" steel ball falling at 50" note: different than standard non safety lenses Standard trifocals have an intermediate that is: a. 2/3 of the near add b. 1 diopters more than the distance c. 50% of the near add d. 5mm deep - ANSWER c. 50% of the near add Standard trifocals have an intermediate that is 50% of the addition of the near. Note: the most often used trifocal is 7mm deep in the intermediate zone. and 25 or 28 mm wide The standard seperation between segments in a double-D segment occupational lens is; a. 22mm b. 13mm c. 16mm d. 25 mm - ANSWER b. 13mm The standard separation between double-D segments is 13mm. This goes back to production difficulties when only fused segments are available. Different separations can be made. Which of the following can reduce edge thickness of a minus lens. a. Edge coating b. polish edge c. a hide a bevel. d. A myodisc - ANSWER D. A myodisc Lenticular lenses have the power in only relatively small central area. This can greatly reduce the thickness of the lens. Minus Lenticular lenses are commonly called myodiscs. Diagram - ANSWER Diagram RX: OD +2.50 sph OS- +2.50 -2.50 x 180 Add: +2.00 OU If the above rx was made in a bifocal, how much prism imbalance would be induced at a reading level 10mm below the distance optical center a. 2.5 diopters b. 5 diopters c. none d. 1.25 diopters - ANSWER A. 2.5 Diopters