NCLE Advanced Certification Exam Questions With Answers Graded A+

NCLE Advanced Certification Exam Questions With Answers Graded A+. The wetting angle of a rigid gas permeable material describes how a fluid spreads over the surface. It is important to remember, however, that wetting angle is a description of the material outside of the patient's natural ocular environment. Within minutes of insertion, a rigid lens is encapsulated in the natural tear mucin and the wetting angle of the material is no longer important. - Answer 8. Which of the following describes the angle that the edge of a bead of water makes with the surface of a plastic? A. Wetting angle B. Surface angle C. Bead angle D. Reflection angle The answer is B. The back surface of a rigid lens will usually correct only the astigmatism that is found on the surface of the cornea. Therefore, when there is significantly more astigmatism in the refraction than on the surface of the cornea, residual astigmatism is anticipated. - Answer 9. If a patient has 1.50 D of refractive cylinder and keratometer readings of 44.00@ 180/ 44 .50 @ 90, a spherical rigid gas permeable lens will: A. Give the patient their best correctable vision B. Usually result in residual astigmatism C. Fit poorly D. Be uncomfortable The answer is C. Lenticular astigmatism usually exists when the amount of refractive cylinder is greater than the amount of corneal cylinder. It is assumed that the additional astigmatism originates in the crystalline lens. - Answer 10. If a patient has spherical K readings of 43.50 and an Rx of -4.00 +1.75 cx 90, the patient has: A. Corneal astigmatism B. Against the rule astigmatism C. Lenticular astigmatism NCLE Advanced Certification Exam With Correct Answers D. Mixed astigmatism The answer is B. With regular astigmatism, even high degrees, a soft toric lens can work quite effectively. Presbyopic and aphakic patients can also be successfully fit with soft lenses. However, patients with irregular astigmatism will achieve their best visual acuity only with rigid gas permeable lenses since soft lenses will mold to the corneal contour and not mask the irregularity. - Answer 11. In which of the following situations is a rigid gas permeable lens always preferred over a soft lens? A. Regular astigmatism B. Irregular astigmatism C. Aphakia D. Presbyopia The answer is A. Decreasing the optical zone diameter while steepening the base curve of a rigid gas permeable lens will allow the lens to cornea relationship to remain the same, since decreasing the optical zone diameter loosens the lens to cornea relationship and steepen- ing the base curve tightens the relationship. Increasing the overall lens diameter also tightens the fit and will only exaggerate the change made to the lens to cornea relationship. Decreasing the center thickness or increasing the lens power will have no significant effect on the relationship of the lens to the cornea. - Answer 12. In order to steepen the base curve of a rigid gas permeable lens without changing the lens to cornea relationship, you would also need to: A. Decrease the optical zone diameter B. Decrease the center thickness C. Increase the overall lens diameter D. Increase the lens power The answer is B. Increasing the overall lens diameter or increasing the optical zone diameter will steepen the lens to cornea relationship. Conversely, decreasing the optical zone diameter, decreasing the overall lens diameter or flattening the base curve will loosen the relationship. If one change is made that tightens the relationship and another is made that loosens it, the changes will cancel each other out. - Answer 13. To steepen the lens to cornea relationship of a rigid gas permeable lens you could : A. Increase overall diameter and decrease optical zone diameter B. Increase overall diameter and increase optical zone diameter C. Increase optical zone diameter and decrease overall diameter D. Increase optical zone diameter and flatten base curve The answer is D. NCLE Advanced Certification Exam With Correct Answers Modification of rigid gas permeable lenses is a valuable skill and can increase a practitioner's success at RGP fitting. Many in-office modifications can be utilized to improve the positioning of a lens, reduce discomfort for the patient and eliminate corneal staining. - Answer 14. Which is not an indication for modifying a rigid gas permeable lens? A. Corneal staining B. Poor lens position C. Discomfort D. Surface Wettability The answer is D. Many modifi~ations to rigid gas permeable lenses can be done in the office, saving time and improving service. Blending peripheral curves, adding minus power, adding plus power, polishing the edges, polishing the anterior and posterior surfaces, as well as reducing lens diameter are all examples of modifications that can be performed in the office. - Answer 15. Which of the following modifications can be made to a rigid gas permeable lens in the office? A. Blending B. Changing the power C. Polishing the edge D. Changing the base curve The answer is A. Lenses that position temporally or inferiorly are not typically indicated and should be avoided. Lenses that position superiorly are often lenses that have been designed with the apical alignment philosophy and have been fit flatter than the flattest keratometer reading in order to achieve this alignment. Lenses that are fit with apical clearance are fit steeper than the flattest corneal measurement and often will fit intrapalpebrally or centrally. - Answer 16. To achieve a lens to cornea relationship that exhibits apical clearance, the lens is designed steeper than the flattest corneal measurement. This lens will most often position: A. Centrally B. Temporally C. Superiorly D. Inferiorly The answer is C. The two visual systems utilized by rigid gas permeable bifocals are simultaneous and alternating. With simultaneous vision systems, both near and far images are received by the retina at the same time. Concentric and aspheric bifocal lens designs utilize simulta- neous vision principles. With alternating vision systems, the lens will NCLE Advanced Certification Exam With Correct Answers move on the eye, delivering the focal length that is in front of the pupil as the lens translates . Segmented bifocal lens designs fall into this category. - Answer 17. Which of the following are visual systems used by rigid gas permeable bifocal lenses? A. Translating and hyperopic B. Simultaneous and instantaneous C. Simultaneous and alternating D. Truncated and prism ballasted The answer is D. Most translating or alternating rigid gas permeable bifocal lenses must be stabilized in order for the proper segment to align correctly with the pupil. Two methods of accomplishing this are by truncating and/ or prism ballasting the lens. In truncation, the bottom portion of the lens is removed, producing a straight edge that interacts ·with the lid and aligns the lens in its proper position. With prism ballasting, the bottom portion of the lens is made thicker than the top portion. Following the same principles as prism ballasting of a soft toric lens, the thicker portion of the lens will be forced from under the upper lid to an inferior position. - Answer 18. Which of the following are methods for stabilizing the rotation of rigid bifocal contact lenses? A. Back surface toric and front surface toric B. Edge roll and polish C. Alternating and translating D. Truncation and prism ballast The answer is D. Flattening the base curve of the lens and decreasing the overall diameter will each decrease the sagittal depth of the contact lens. By combining both factors, the impact will be magnified. Steepening the base curve and increasing the overall diameter will both increase the sagittal depth. - Answer 19. To decrease the sagittal depth of a rigid gas permeable contact lens you can: 1. Steepen the base curve 2. Flatten the base curve 3. Increasetheoveralldiameter 4. Decrease the overall diameter A. 1and4 B. 1and3 C. 2and3 D. 2and4 The answer is B. NCLE Advanced Certification Exam With Correct Answers Dimple veil staining is not traditional staining but is rather a pooling of fluorescein in depressions or "dimples" on the surface of the cornea. These dimples are caused by air bubbles that become trapped behind a rigid lens in an area where the distance between the lens and cornea is too great. Dimples will be found centrally if the base curve is too steep and peripherally if the base curve or peripheral curves are too flat. - Answer 20. Dimple veil staining on the cornea is caused by: A. Poor polishing of peripheral curves B. Air bubbles trapped under a rigid lens C. Debris trapped under a rigid lens D. A cracked contact lens The answer is B. The parameters listed in C and D will flatten the lens to cornea relationship. While answer A does steepen the lens' relationship, it does not take into account the change in the power that is necessary when the base curve of the lens is altered. - Answer 21. The GP multifocal design that relies on the use of a variable rate of curvature across the lens surface to achieve a change in power is known as: A. Concentric B. Translating C. Aspheric D. Truncated The answer is B. "Dk/L" stands for the oxygen transmissibility of a specific lens when manufactured with a given center thickness. "Dk" stands for the oxygen permeability of the material, but the actual transmission of oxygen thr ough this material is also dependent on the thickness of the lens. While the concept of permeability is important to understand, the real impact is found in the transmissibility of the lens. Wetting angle relates to the ability of tears to spread on the plastic, specific gravity relates to the weight of the lens material and neither are related to corneal oxygenation. - Answer 22. To allow for proper corneal oxygenation when fitting rigid gas permeable lenses, which of the following material characteristics must be considered? A. Dk B. Dk/t C. Wetting angle D. Specific gravity The answer is C. To determine the parameters of a bitoric rigid lens, place the most plus (least minus) power on the flattest meridian (-2.00 Don the 42.00 D meridian) and the most minus (least plus) on the steepest meridian (-2.00 D plus an additional -5 .00 D, for a total NCLE Advanced Certification Exam With Correct Answers of -7.00 Don the 45.25 D meridian). The -7.00 D must be vertexed, which results in - 6.50 D. Since we are fitting the lens "on K", the final lens parameters are 42.00 / 45.25 -2.00/-6.50. - Answer 23. Given the following information: K's 42.00@180/45.25@90 Rx -2.00 -5.00 cx 180 Which of the following specifications, given in actual drum readings, would represent a bitoric lens fit "on K"? A. 42.00/45.25 -2.00 /-3.00 B. 42.00/45.25 -2.00 /-5.00 C. 42.00/45.25 -2.00 /-6.50 D. 42.00/45.25 -2.00 /-9.00 The answer is A. The only listed set of specifications that will give the patient a good visual result is answer A. In this case, the lens is fit 0.50 D flat in the horizontal meridian and is 0.50 D flat in the vertical meridian. To determine the lens power, work with the patient's refraction in minus cylinder and apply the principles of "SAM/FAP" (Steep Add Minus, Flat Add Plus) to the sphere power only. In this case, the flattest meridian was fit 0.50 D flatter, creating 0.50 D of minus power. To compensate for this, 0.50 D of plus must be added to the -1.00D of sphere power in the patient's Rx, resulting in - 0.50D. The 3.000 of refractive cylinder is corrected by the 2.00 D of cylinder on the posterior surface of the lens. Back surface toric lenses will correct refractive cylinder that is 1 1/ 2 times the amount of cylinder on its back surface. While all back surface toric lenses do not need to be fit 0.50 D flatter than Kin both principal meridians, none of the other options listed will result in an appropriate lens prescription . - Answer 24. Given the following patient information: K's 41.25@180 / 43.25@90 Rx -1.00 -3.00 cx 180 The best parameters for a back surface toric rigid gas permeable lens would be: A. 40.75/42.75 -0.50 B. 40.75/43.25 -1.00 C. 41.25/43.25 -4.00 D. 41.25/44.25 -1.00 25. The answer is D. A front surface toric lens will show clear mires in all meridians which indicates a spherical posterior surface. Warped, bitoric and back surface toric lenses will all show unclear mires in the radiuscope indicating that the posterior surface is not spherical. In the lensometer, bitoric, back toric and front surface toric lenses will all display sphero-cylindrical readings. Only the warped lens will show a spherical lensometer reading. - Answer 25. When verifying the posterior curves of a rigid gas permeable not all of the mires are clear in all meridians. This can occur in all but a: A. Warped lens NCLE Advanced Certification Exam With Correct Answers B. Bitoric lens C. Back surface toric lens D. Front surface toric lens The answer is D. VLK, or Vascularized Limbal Keratitis, is a condition associated with rigid gas permeable lenses, predominantly those lenses that are designed with low edge lifts and large diameters. In its most advanced stage, a heaping of the corneal epithelium in the area of irritation becomes evident. This area becomes vascularized from the conjunctiva to the limbus leading to the elevated mass in the area. Staining on the cornea and conjunctiva accompany patient symptoms which may include reduced wearing time, redness, photophobia and in some instances, pain. - Answer 26. Heaping of epithelium, vascularization, and staining of the conjunctiva and cornea are characteristic of... A. Corneal warpage B. Gian papillary C. Vascularized limbal keratitis D. Dendritic keratitis The answer is D. When adding a spherical over-refraction to a bitoric lens, it must be added to both meridians Example: -1.00 / -4.50 -1.00 / -1.00 -2.00 / -5.50 - Answer 27. Lens specifications in actual drum readings: 43.50/45.50 -1.00/-4.50 9.2 Over-refraction: -1.00 sphere What is the new lens power? A. plano/-3.50 B. -1.00/-5.50 C. -2.00/-4.50 D. -2.00/-5.50 The answer is D. Decreasing the height of the bifocal segment is the only option that will drop the seg and alleviate the visual confusion caused by the segment bisecting the pupil. All of the other options will move the bifocal segment further up into the line of vision. - Answer 28. A translating bifocal wearer complains of blur at distance. Upon slit lamp exam, you notice that the bifocal segment bisects the pupil. In order to improve this situation, you should: A. Increase the seg height NCLE Advanced Certification Exam With Correct Answers B. Decrease truncation C. Decrease prism ballast D. Decrease seg height The answer is B. Dimple veil staining may occur when there is either a steeper or flatter than recommended lens to cornea relationship. Air bubbles become trapped in the excessive space and create dimples on the corneal surface. Antibiotics will not affect dimple veil staining, nor will lenticulating the edges. Re-evaluating the lens to cornea relationship will identify the problem and allow the fitter to change the base curve and/ or peripheral curves to eliminate the dimples. - Answer 29. Dimple veil staining is resolved by: 1. Antibiotics 2. Steepening the lens to cornea relationship 3. Flattening the lens to cornea relationship