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NCLE Advanced Certification Exam with
COMPLETE SOLUTION | 459 Questions with 100%
Correct Answers 2024
The answer is D. The posterior optical zone will directly affect the lens to cornea relationship of a rigid gas permeable lens. If the posterior optical zone is steepened, it will increase the sagittal depth. If it is flattened, it will decrease the sagittal depth. Changing the power, which is accomplished by changing the anterior optical zone, will not affect the sagittal depth of the lens, nor will changing its edge design. - Answer 1. The sagittal depth of a rigid gas permeable contact lens can be altered without changing the diameter by: A. Changing the power B. Changing the edge design C. Changing the radius of curvature of the anterior optical zone D. Changing the radius of curvature of the posterior optical zone The answer is A. A lens is truncated by removing a segment of the lower edge of a contact lens. This creates a straight edge that interacts with the lower lid and aids in lens positioning. Of the lens designs listed in the question, the only one that requires precise positioning of its optical portions is a translating bifocal lens. - Answer 2. A truncation is used on a rigid gas permeable contact lens to help enhance the performance of which type of design? A. Bifocal B. Aphakic C. Bitoric D. Keratoconus The answer is B.
A lenticular or myoflange design will decrease the mass of an aphakic lens as well as increase the edge profile, which allows it to interact more with the upper lid and aid in positioning of the lens. - Answer 3. The mass of an aphakic rigid gas permeable contact lens can be reduced by making the lens design: A. Spherical B. Lenticular C. Tricurve D. Aspheric The answer is B. Increasing the optical zone diameter and increasing the overall lens diameter will both tighten and steepen the relationship of the lens to the cornea. Decreasing the optic zone diameter will serve to flatten and loosen the lens to cornea relationship. Using a prism-ballasted lens design will not affect the lens to cornea relationship as it relates to sagittal depth.
- Answer 4. In order to tighten the fit of a rigid gas permeable lens you can: I. Increase the optical zone diameter
- Decrease the optical zone diameter
- Increase the overall lens diameter
- Use a prism ballasted lens design A. 3 only B. 1& C. 2 only D. 2& The answer is D. A hyperflange will decrease edge thickness as well as lens awareness. Aspheric peripheral curves change the posterior design of the lens but do not reduce edge thickness. A higher Dk material will not change the overall lens edge thickness. A myoflange will actually add thickness to the lens edge and is used for high plus lenses not high minus lenses. - Answer
- A high minus rigid gas permeable lens will be thin centrally with relatively thick edges. To reduce the edge thickness, and increase overall comfort, use: A. Aspheric peripheral curves B. A myoflange C. A higher Dk material D. A hyperflange The answer is C. One would rarely polish or attempt to manipulate the central posterior surface of a rigid lens. Applying polishing pressure to the mid-peripheral and the peripheral anterior surface would add plus power. Applying polishing pressure to the central anterior surface would add minus power. - Answer 6. To add minus power to a rigid contact lens with a rotating modifying spindle, one would:
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 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
- 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. 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
D. 2and The answer is B. 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.
permeable not all of the mires are clear in all meridians. This can occur in all but a:
A. Warped lens 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. -1.00 / - 1. -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. B. -1.00/-5. C. -2.00/-4. D. -2.00/-5. 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 B. Decrease truncation
VascularizedUmbal Keratitis (VLK)is believed to be caused mainly by large diameter rigid gas permeable lenses with low edge lifts. These lenses chafe the epithelium in the limbal area in the three and nine o' dock areas, The tear film in the area may also be altered by this traumatic mechanical effect and has a synergistic effect in causing the vasogenic response known as VLK. - Answer 32. Vascularized Limbal Keratitis is usually caused by: A. Dry eye syndrome B. Allergic reaction to solutions C. Mechanical irritation D. Excessive exposure to ultraviolet radiation The answer is A. When comparing wetting angles, the greater the angle, the less hydrophilic is the lens material. A drop of fluid that creates a 90 degree angle between the drop and the surface is considered an indication of a hydrophobic surface. When there is an angle of 0, the material is considered completely wet. The smallest wetting angle represents the most wettable surface, which is most desirable in RGP materials. - Answer 33. When comparing wetting angles, which of the following would be the most desirable? A. 10 B. 20 C. 30 D. 60 The answer is B. A drop of fluid that creates an angle of 90 degrees or greater is considered an indication of a hydrophobic or non-wetting surface. A drop of fluid that creates an angle of 0 to 90 degrees indicates a more wettable material with the lowest values representing the most wettable surfaces. A drop of fluid that creates an angle of O indicates that the material is totally hydrophilic. - Answer 34. The greater the ability of a rigid gas permeable lens to wet, the the wetting angle? A. Higher B. Lower C. Deeper D. Rounder The answer is C. Oxygen transmissibility is useful clinically as an indication of oxygen delivery. This is because it represents the amount of oxygen moving through a specific lens with a given thickness instead of simply the oxygen moving through a plastic of unknown thickness, since the oxygen delivery will vary according to the thickness of the lens. - Answer 35. Dk/t is:
A. Oxygen Permeability B. Lens Thickness C. Oxygen Transmissibility D. Specific Gravity The answer is A. Imagine a contact lens as a portion of a sphere. Assuming that the diameter of a lens is kept constant, if the base curve of a lens is steepened, the distance from the lens periphery to the imaginary center of the sphere will be shorter. (See diagram) The base curve of a lens is expressed by the length of its radius. The shorter the radius, the steeper the curve, conversely the longer radius, the flatter the base curve. Therefore, when the posterior radius of curvature is decreased, the base curve of the rigid gas permeable lens is made steeper. Diameter is constant in each lens, 14mm. The shorter the radius the steeper the lens. - Answer 36. When the base curve of a rigid gas permeable lens is said to be made steeper, it means that the posterior radius of curvature is: A. Decreased B. Divided C. Increased D. Elongated The answer is B. Decreasing edge thickness will allow the lid to re-wet the affected area in the corneal periphery. A base curve cannot be steepened nor can the diameter of a lens be increased, either in the lab or in the office and a new lens would have to be ordered if these changes were required. A diameter gauge is a measuring instrument, not a modification tool. - Answer 37. What in-office modification can be performed to alleviate three and nine o'clock staining? A. Steepen the base curve with a conical tool B. Decrease edge thickness with a conical tool C. Flatten the base curve with a conical tool D. Increase the diameter with a diameter gauge The answer is D. When a rigid gas permeable lens flexes on the eye, the patient will notice a number of phenomena. The most obvious is the fluctuation in vision that occurs during the blink. Continuous flexing of the lens on the eye may also result in a lens that warps over time and can lead to decreased comfort. - Answer 38. Higher Dk materials and high minus prescriptions present a greater chance for the contact lens to flex excessively on the eye. This may result in which of the following situations? A. Variable acuity B. Discomfort C. Warped central posterior curve D. All of the above
An inverted or flat fitting lens will often display edge lift or stand off. - Answer 42. The thickness of a soft contact lens will affect the: A. Oxygen transmissibility of the lens B. Power C. Opaque Tint D. Patients visual acuity The answer is A. Three point touch refers to the relationship of the soft lens to the cornea. The lens should make contact centrally with the corneal apex, vault the limbus, and have its edges rest on the sclera. Ultra-thin soft lenses, due to their flexure, may drape the cornea completely. A soft lens should never be fit with apical clearance, as this will result in fluctuating vision and seal off in the periphery, resulting in a tight fit. - Answer 43. Soft lens fitting should result in: A. Three point touch B. Apical clearance C. Upper lid attachment D. None of the above The answer is D. The general rule of thumb in choosing a soft lens diameter is that it should be at least 2.0 mm larger than the HVID. If the HVID is 11.0mm, the smallest soft lens diameter should be 13.0 mm. - Answer 44. If the HVID (Horizontal Visible Iris Diameter) is 11.0mm, the minimum diameter soft lens you should choose is: A. 14.5 mm B. 14.3 mm C. 14.0 mm D. 13.0 mm The answer is B. The overall lens diameter and the curve of the posterior portion of the lens determine the sagittal depth of any contact lens, soft or rigid. The larger the diameter and/ or the steeper the base curve, the greater the sagittal depth. Conversely, the smaller the diam- eter and/ or the flatter the base curve, the smaller the sagittal depth. - Answer 45. The sagittal depth of a soft lens is determined by: A. Diameter and power B. Base curve and diameter C. Diameter and water content D. Base curve and thickness The answer is C. Decreasing the lens diameter and flattening the base curve will only serve to loosen this already flat lens. Increasing the center thickness may also loosen the lens fit, as
it de- creases capillary attraction and results in greater lens movement. - Answer 46. A soft lens displays inferior edge lift on the eye. What can be done to remedy this situation? A. Decrease lens diameter B. Flatten base curve C. Steepen base curve D. Increase center thickness The answer is C. Tint is the only characteristic listed that does not influence the fit of a soft contact lens. Changes in diameter, water content or sagittal depth will affect the soft lens fit. - Answer 47. Which characteristic of a soft lens does not affect the fit? A. Diameter B. Sagittal depth C. Tint D. Water content The answer is B. The most reliable method of assessing the fit of a soft lens is to put your thumb on the lower lid, have the patient look up slightly and push the lens up. If the lens moves freely without much force and then moves gently back into place, it is considered a good fit. Asking the patient how the lens feels should not be a criterion for final evaluation, as patients will usually choose lenses that are initially tight. Fluorescein evaluation will not provide information about the fit of a soft lens and may be absorbed by the lens, causing discoloration. - Answer 48. The most effective method of assessing the fit of a soft contact lens is: A. Asking the patient how it feels B. Push up test C. Fluorescein evaluation D. Slit lamp observation with optic section The answer is B. The larger the diameter, the greater the sagittal depth if the base curve is kept the same. The 14.5 diameters have a greater sagittal depth than their 14.0 counterparts. The steeper the base curve, the greater the sagittal depth. That would mean that the 8.4 would result in a greater sagittal depth than the 8.8 indicating that the 8.4/14.5 lens would have the greatest sagittal depth. - Answer 49. If all of the following soft lenses are made with the same design and material, which should have the greatest sagittal depth? A. 8.4/14. B. 8.4/14. C. 8.8/14. D. 8.8/14.
B. Horizontal Visible Iris Diameter C. Hydrogel Viewing Interstromal Device D. Horizontal VerticalIris Diameter The answer is A. Cast molding of a soft contact lens results in very consistent lens parameters which allows manufacturers to produce the vast quantities of lenses needed to satisfy the disposable lens market. Lathe cutting is a more costly and labor-intensive method of manufacturing soft lenses and is used for conventional lenses. Spin casting causes the posterior surface of the lens to change as the power increases and results in an aspheric design and a less predictable fit. - Answer 53. The manufacturing process most often used for disposable contact lenses is: A. Cast molding B. Lathe cut C. Spin cast D. Wax molding
- The answer is B. Soft toric lenses are generally made with cylinders of 0.75 D and greater. While not all patients with only 0.75 D of cylinder will require a soft toric lens, this should be a starting point for discussion and evaluation of the need for a soft toric lens to provide the best visi_onfor the patient. - Answer 54. What is the least amount of cylinder a patient should have before soft toric lenses are discussed? A. 0.25 D B. 0.75 D C. 1.25 D D. 2.00 D The answer is A. Discharge, itching and lens displacement in a long time soft lens wearer are classic symptoms of GPC (Giant Papillary Conjunctivitis). Everting the upper lid and looking for enlarged papillae and injection will help the practitioner make the positive diagnosis. - Answer 55. When a longterm soft lens wearer complains of discharge, itching, and an occasional pulling up of the lens by the upper lid, the practitioner should: A. Evert the upper lid and check for GPC B. Remove the lens and check for follicles C. Raise the upper lid and check for SLK D. Pull the lower lid down and check for jelly bumps The answer is C.
Soft toric lens manufacturers generally begin with cylinder powers at 0. D. Cylinder power requirements less than that are usually not corrected with a toric lens design. While custom soft toric lenses can correct 4.00 D and more of refractive cylinder, the standard range is usually Jess than 3.00 D. - Answer 56. What is the average cylinder power range of standard toric soft lenses? A. 0.25 to 1.50 D B. 0.25 to 2.50 D C. 0.75 to 2.50 D D. 0.75 to 4.00 D The answer is A. The FDA Classifications for soft lens materials are grouped by the water content of the material (low water versus high water) and the electrical charge on their surface (ionic versus non-ionic). Contact lens materials that carry an electrostatic charge are ionic and lens materials that do not carry an electrostatic charge are classified as non-ionic. The neutrally charged lens materials (i.e. non-ionic) are less likely to attract the positively charged proteins and lipids in the tear film. Soft Jens materials that are classified as low water, non-ionic are considered the most deposit resistant materials. - Answer 57. Which of the following soft lens material groups is considered the most resistant to deposit formation? A. Low water, non-ionic B. High water, non-ionic C. Low water, ionic D. High water, ionic The answer is D. The lens material group that is considered the least resistant to deposit formation is the high water, ionic (negatively charged lens surface) lens material. It is also the lens material that is most reactive to solutions and their preservatives. - Answer 58. Which of the following soft lens material groups is considered the least resistant to deposit formation? A. Low water, non-ionic B. High water, non-ionic C. Low water, ionic D. High water, ionic The answer is D. Daily disposable lenses or single use lenses are approved to be worn for only one day and then thrown away. They have not been approved to be used with solutions, nor should they need to be, as they must be discarded after one use. - Answer 59. The approved protocol for single use lenses is: A. Clean and disinfect daily B. Clean and disinfect weekly
