CLSA CD Questions Flashcards

Question

25. Which of the following soft lens materials is most likely to become coated with deposits? A. Low water content non-ionic B. High water content non-ionic C. Low water content ionic D. High water content ionic

Answer 1

D. High water content ionic

Answer 2

A. Giant papillary conjunctivitis

Answer 3

C. Eye Lids

Answer 4

B. Increase overall diameter and increase optic zone diameter

Answer 5

B. Pinguecula

Answer 6

B. Cornea 42 D to 43 D

Answer 7

A. Endothelium

Answer 8

D. Root of the iris, portion of the anterior ciliary body, scleral spur, trabecular meshwork and Canal of Schlemm

Answer 9

B. Elevated intraocular pressure, visual field loss and damage to the optic nerve head

Answer 10

B. A thick, jelly-like structure that fills the posterior 2/3 of the eye

Answer 11

B. One week

Answer 12

C. 44.50 @ 15 / 44.75 @ 105

Answer 13

D. Posterior toric lens ## Footnote Fluorescein patterns can be very helpful in determining the final fitting parameters of an oxygen permeable contact lens. Areas that are bright green reflect areas where there is a great deal of distance between the posterior surface of the lens and the anterior surface of the cornea. When areas are dark, they indicate areas where there is little space between the back of the lens and the front of the eye. When the fluorescein pattern of a spherical RGP lens shows a black shaped area of touch in one meridian opposed to an area of excessive lift, the best way to improve this fit is with an oxygen permeable lens that has two separate curves on the back (posterior) surface of the lens. An aspheric lens may be the next best choice, but it will only minimize the differences, not completely eliminate them.

Answer 14

A. Truncation

Answer 15

A. Decreasing the overall diameter

Answer 16

B. Edge stand off

Answer 17

A. Therapeutic bandage lens A therapeutic bandage lens would be the best choice. Most lenses that are designed as bandage lenses, allow the patient to wear the lens on a continuous, overnight basis. While the other choices may also work, they may not be the best choice. Rigid lenses, because they are smaller, may not give enough coverage. Conventional daily wear and toric soft lenses are not as good if the patient needs to sleep with the lenses.

Answer 18

C. Simultaneous and alternating The two visual systems utilized by rigid gas permeable bifocals are simultaneous and alternating. With simultaneous vision systems, the retina receives both near and far images at the same time. Concentric and aspheric bifocal lens designs utilize simultaneous vision principles. With alternating vision systems, the lens will move on the eye, delivering the focal length that is in front of the pupil as the lens translates or moves on the eye. Segmented bifocal lens designs fall into this category.

Answer 19

C. Chalazion

Answer 20

A. Incomplete eyelid closure

Answer 21

C. 11.5 mm

Answer 22

A. 32.00 D ## Footnote By applying a -1.00 D lens to the aperture of the keratometer, the range of the instrument can be extended from 36.00 D down to 30.00 D. Six diopters should be subtracted from the actual drum reading to arrive at the patient's estimated keratometric value. The opposite can be achieved by placing a +1.25 D lens to the keratometer to extend the range upward from 52.00 D to 61.00 D. In this case, adding 9.00 D to the results will give the contact lens professional an approximate reading.

Answer 23

C. Solution sensitivity Solutions can easily be the cause of burning, stinging, dryness and limbal to limbal superficial punctate keratitis. To rule the patient's solutions out, a change in the care products can be made to see whether the symptoms persist. If the patient is wearing conventional soft lenses and does not replace them on a frequent basis, this should be attempted with a new pair of contact lenses as older lenses may harbor some of the preservatives to which the patient is sensitive.

Answer 24

B. 2 mm larger than the HVID The general rule of thumb is to fit a soft contact lens 1 mm larger on each side of the HVID (or 2 mm in total). This will allow the lens to cover the corneal surface, vault the limbus and extend out onto the sclera. While every contact lens professional may follow a slightly different guideline, this standard has been accepted throughout the industry for many years and tends to be the average choice of many fitters.

Answer 25

C. Corneal swelling

Answer 26

A. Exposes the nerve endings

Answer 27

C. Keratoconus

Answer 28

C. Sensitivity to preservatives in care products SPK (superficial punctate keratitis) caused by solution sensitivity is usually diffuse because the chemicals in the offending solution come in contact with the entire cornea. Mechanical trauma may take the form of foreign body tracks, swirl patterns or arcuate staining from a poor edge, poor blinds, or deposits on the lens. Dimple veiling is the term used for tiny air bubbles that are trapped under a rigid lens that is not fitting properly. Central dimples indicate an excessively steep lens to cornea relationship. Bubbles in the periphery indicate that the lens is too flat. A poor insertion or removal technique may result in an arcuate impression of the lens edge where it hits the cornea, or sector staining in those portions of the cornea that are pinched during soft lens removal.

Answer 29

B. Bowman's membrane was not affected The cornea is comprised of five layers: epithelium, Bowman's membrane, stroma, Descemet's layer and endothelium. The corneal epithelium is the only layer that can regenerate cells if they become damaged. If Bowman's membrane is compromised through injury, it will result in scarring.

Answer 30

A. Lens Binding ## Footnote One of the classic signs of lens binding is an arcuate shaped stain when no previous staining was evident. Even if the lens is moving well at the time of the check up, lens binding maybe the cause. You may have to see the patient at a later time of the day to see the binding. If it is an extended wear RGP wearer, see them in the morning for their exam.

Answer 31

C. Mechanical irritation Vascularized Limbal Keratitis (VLK) is believed to be caused predominantly by large diameter rigid gas permeable lenses with low edge lifts. These lenses chaff away at the epithelium in the limbal area along the three and nine oâclock areas. The tear film in the area may also be altered from this traumatic mechanical effect. This all may compound to set in motion the vasogenic response known as VLK.

Answer 32

D. Decrease seg height 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 33

D. All of the above

Answer 34

B. A lesion in the superior cornea "SEAL" stands for Superior Epithelial Arcuate Lesion and is characterized by an epithelial lesion of 1 to 3 mm. It is typically 1 mm from the superior limbus, arcuate in shape and parallel to the limbus. Found among soft lens wearers, it is generally considered to be the result of the soft lens that does not flex enough to conform to both the flat sclera and steeper cornea. The upper lid rubs the lens into the superior cornea, causing the epithelium to split. Discontinuing lens wear until the condition resolves and then refitting with a different soft lens design will solve the problem.

Answer 35

A. 3 to 5 days Limbal epithelial hypertrophy is a change in the peripheral cornea due to a tightly fitting soft contact lens. Clinical findings include a wrinkled or furrowed pattern outside of the limbal area. This is best viewed with the application of fluorescein. Once the lens is removed, the condition typically resolves itself within 3 to 5 days. It is then best managed by refitting the patient with a more loosely fitting soft lens.

Answer 36

A. Outward turning of the eyelid

Answer 37

C. Fat deposits in the stroma

Answer 38

C. Keratoconus

Answer 39

A. Anterior Chamber

Answer 40

A. Aniridia or iridectomy Aniridia and an iridectomy represent one natural and one surgical condition respectively that result in the total or partial absence of the iris. Since the iris is responsible for controlling the amount of light that enters the eye, when part or all of it is missing, the patient suffers from a great deal of photophobia. A painted iris contact lens will help shield the eye from excessive amounts of light.

Answer 41

C. Dimple Veil

Answer 42

D. 2 and 4 Flattening the base curve of the lens and decreasing the overall diameter will both decrease the sagittal depth relationship of the contact lens. By combining both of these factors, the impact will be the increased. Steepening the base curve and increasing the overall diameter of the lens will increase the sagittal depth.

Answer 43

D. The apex location of keratoconus

Answer 44

B. Excessive lens movement A lens that prevents tear exchange and elimination of corneal debris and metabolic waste products may cause corneal edema, sensations of soreness, injection, foggy vision and ghost images.

Answer 45

A. Control reflex tearing

Answer 46

B. Against-the-rule astigmatism

Answer 47

D. Descemet's membrane ## Footnote Descemet's membrane is a condensation of collagenous protein and is 2 - 3 microns thick in newborns. It increases in thickness over time to 5 - 7 microns centrally and 8 - 10 microns peripherally.

Answer 48

D. Descemet's membrane

Answer 49

B. Superior limbic keratoconjunctivitis Superior limbic keratoconjunctivitis (SLK) is characterized by superior bulbar conjunctival hyperemia, punctate staining of the superior cornea and limbus, mild superior tarsal papillary hypertrophy, grayish-white sub-epithelial and intraepithelial opacities and superior vascularization of the cornea. The cause of SLK is not fully understood, but solution hypersensitivity should be strongly suspected in these cases. Superior epithelial arcuate staining (SEAL) does not impact the bulbar conjunctiva nor the tarsal conjunctiva. It also does not result in opacities or vascularization of the cornea. Giant papillary conjunctivitis and vernal keratoconjunctivitis affect the tarsal conjunctiva only.

Answer 50

D. Palpebral conjunctival vasculature Hemoglobin delivers oxygen to the anterior cornea by diffusion from the palpebral conjunctiva during the closed eye state. The atmosphere is responsible for the majority of oxygen to the anterior cornea during the open eye state. The aqueous humor supplies limited amount of oxygen to the posterior cornea and the limbal vessels supply a small amount to the very periphery of the cornea

Answer 51

C. Will resolve itself in a few days without treatment Subconjunctival hemorrhages are much more frightening in appearance than they are in reality. If a blood vessel in the conjunctiva leaks or is disrupted, a small pooling of blood may form underneath the conjunctiva. The blood will appear bright red and may continue to spread below the conjunctiva after it first is formed. However, within a few days, the blood will be absorbed again and the hemorrhage will clear. These small hemorrhages typically occur spontaneously without the presence of any trauma. It is important to differentiate between a subconjunctival hemorrhage and a hyphema. With a hyphema, blood is leaked within the eye typically after a severe trauma or injury to the eye. Referral to an eye doctor is recommended as the risk of secondary glaucoma or a rebleed is heightened.

Answer 52

C. Irregular Keratoconic corneas most often display irregular astigmatism. In some cases, particularly early in the condition, the cornea may have a definite with- or against-the-rule orientation and there may even be an internal component. However, as the condition advances, a more irregular topography evolves. It is this irregular surface that challenges the vision of the patient. Since the surface does not conform to the "normal" or "regular" meridional shape, it becomes more and more difficult to find the true amount or axis of the astigmatism. Patients with severe irregular astigmatism can hope for their best vision through spherical oxygen permeable lenses. This spherical surface re-creates a regular surface for the light rays to enter, improving and enhancing vision.

Answer 53

A. Fluorescein and a blue cobalt filter Particles or debris that become trapped between the posterior surface of a contact lens and the anterior surface of the cornea may leave behind small foreign body tracks that can be viewed with the slit lamp using fluorescein and a blue cobalt filter. The use of a yellow Wratten filter will further enhance the presence of these small tracks left behind by the foreign body. A handheld loupe is useful for examining the surface of a contact lens, but is limited in its ability to view the cornea.

Answer 54

D. Crystalline Lens

Answer 55

A dellen can be defined as a depressed area on the cornea, which is generally found adjacent to an elevated area of the cornea. A pinguecula is an elevated area found on the bulbar conjunctiva. A pterygium is also an elevated area of growing membrane that may extend from the sclera onto the cornea. A nevus is a congenital pigmented area found on the iris or the sclera but which has no elevation.

Answer 56

The answer to Question 84 is B. ## Footnote The warm colors of a corneal map represent the steepest or most curved areas of the cornea. While in a keratoconus map this may also represent the area of the cornea that is "highest", the warm colors represent degree of curve, not height. In a cornea that exhibits a with-the-rule orientation, the warm colors are lined up vertically. When the warm colors are lined up horizontally, they exhibit an against-the-rule orientation.

Answer 57

The answer to Question 85 is D. ## Footnote A coloboma is an abnormality that may be found in any of the structures of the eye, usually in the lower half, due to an abnormal development during gestation.

Answer 58

The answer to Question 86 is A. ## Footnote Following penetrating keratoplasty (corneal transplant), a patient will most likely get their best vision with the use of a rigid gas permeable lens. Irregular astigmatism or "graft tilt" are possible following surgery, resulting in poor best corrected vision. Not only will the rigid plastic correct the patient's vision optimally, but also the increased oxygen that is available to the cornea will reduce the threat of neovascularization.

Answer 59

The answer to Question 83 is B. ## Footnote Pannus may be described as an invasion of the peripheral cornea by the infiltration and formation of new blood vessels. These are typically fine, thin vessels that progress slowly and are a result of some type of corneal compromise such as hypoxia, allergic reaction, trauma or disease. While a pterygium is vascularized, it is comprised primarily of a membrane that extends from the conjunctiva to the cornea. A pinguecula is an elevation found on the nasal or temporal bulbar conjunctiva and does not extend onto the peripheral cornea. Ptosis is a drooping of the upper eyelid.

Answer 60

The answer to Question 87 is D. ## Footnote Protein is found in a patient's tear and accumulates on the lens during wear. The amount of deposition is dependent upon the patient's tear make-up and the material used for the lens. Normally, a fluoro-silicone acrylate lens will be more protein resistant than a silicone acrylate. Removing protein is most effectively done by the patient by soaking the lens in an enzyme cleaner on a consistent basis. While polishing the lens will also remove protein, it is less convenient for the patient because it involves a visit to the eye care professional's office.

Answer 61

The answer to Question 88 is C. ## Footnote Band keratopathy is a calcium build-up in Bowman's layer. It may extend across the cornea nasally to temporally. It can result from chronic uveitis or a corneal inflammatory disease. An ophthalmologist can treat it by removing the epithelium and treating the affected area with an EDTA solution to dissolve the calcium.

Answer 62

The answer to Question 89 is A. ## Footnote The presence of a dendrite is a classic sign of the herpes simplex virus. The patient will most likely also present with pain, redness, sensitivity to light, foreign body sensation and a watery discharge. The diagnosis becomes much clearer when the distinctive dendritic lesions are visible. If left untreated, these lesions can cause scarring which can affect the patient's long-term vision.

Answer 63

The answer to Question 90 is B. ## Footnote Pellucid marginal degeneration is a non-infectious, non-inflammatory condition in which the steepening/thinning of the cornea is located with 1-2 mm of the inferior limbus. This results in a classic "butterfly" pattern when corneal maps are performed. Keratometry may typically reveal a flatter than average central reading with a significant against-the-rule orientation. The thin, steepened area of keratoconus is located in the inferior paracentral area of the cornea.

Answer 64

The answer to Question 91 is A. ## Footnote When the cornea is distressed, a normal reaction is for the limbal blood vessels to respond by beginning to encroach upon this normally avascular tissue. Unfortunately, while this does provide extra oxygen and nutrients to the cornea in its time of need, it also encourages blood vessels into an area where they do not belong. Neovascularization of the cornea is a sign that the cornea is in distress.

Answer 65

The answer to Question 92 is A. ## Footnote Corneal hydrops are caused by a rupture in Descemet's membrane. The aqueous expands into the stroma, causing marked swelling and corneal thickening. In most cases, hydrops resolve without surgical intervention, though there may be some residual scarring.

Answer 66

The answer to Question 93 is D. ## Footnote Irregular corneal astigmatism occurs whenever the cornea loses its symmetrical shape as it would with a corneal laceration (shown in this photo), trauma, surgery, keratoconus, pellucid marginal degeneration, herpes simplex keratitis, corneal dystrophies and other conditions that affect the cornea in a non-symmetrical manner.

Answer 67

The answer to Question 94 is C. ## Footnote Limbal epithelial hypertrophy is a localized peripheral corneal change that most often occurs with the use of thick soft lenses that exhibit poor movement on the blink. Patients are most often asymptomatic, but they may notice that comfort has decreased or they have a slight foreign body sensation while wearing the lenses. Discontinuing lens wear until the condition resolves and then refitting the patient into a lens that has increased lens movement will solve the problem.

Answer 68

The answer to Question 95 is C. ## Footnote The traditional classifications of keratoconus include the nipple, oval and globus cones. The smallest of the classifications is the nipple cone, followed by the oval and globus, which may take up the majority of the patient's cornea as is depicted in this picture. This red fundus reflex shows the base of the cone of a dilated patient.

Answer 69

The answer to Question 96 is B. ## Footnote When a keratoconus patient presents with a classic swirl staining pattern, it is indicative of a flat fitting RGP lens. This is a result of the flat lens being rotated nasally as the patient blinks and rubbing against the apex of the cone. Even if the patient is asymptomatic (which they most usually are), the fit should be re-evaluated and improved.

Answer 70

The answer to Question 97 is A. ## Footnote The X-chrome lens, pictured here, is a red tinted lens that is worn on a patient's non-dominant eye to help correct for specific types of color blindness. The results are not always guaranteed, resulting in the rare use of this lens.

Answer 71

The answer to Question 98 is C. When the lens to cornea relationship along the horizontal meridian results in a lack of tear film in that area, desiccation can occur. This can occur when the lens to cornea relationship is too steep in this area, or even when there is excessive edge lift that inhibits the ability of the eyelid to spread tear film on the cornea. This is more commonly referred to as three and nine o'clock staining based on the location of the staining. The reason that the staining occurs in this meridian is because a with-the-rule cornea is flattest along the horizontal (three and nine o'clock) meridian and it comes into contact with the lens in this meridian. Patients whose corneas have an against-the-rule orientation would most likely not be bothered by rubbing in both the three and nine o'clock areas since the lens is closest to the cornea in the vertical meridian on these corneas. Epiphora is excessive tearing.

Answer 72

The answer to Question 99 is D. ## Footnote Aniseikonia occurs when the eye cannot fuse two images because they are so different in size or shape between the two eyes. This may occur from a significant difference in Rx between the two eyes. Amblyopia, a loss of vision without any apparent disease of the eye, may result if aniseikonia goes uncorrected in children since the optic nerves won't receive usable images and the nerve may simply become unable to function properly. Aniridia is the congenital absence of the iris. Anophthalmia is the absence of a true eyeball.

Answer 73

The answer to Question 100 is D. ## Footnote Any contact lens material, PMMA, RGP and soft, has the potential to create a situation of corneal molding or warpage.

Answer 74

Corneal Desiccation (Dry Eye)

Answer 75

Peripheral Staining Dellen Bound Lens Usually Tear Problems

Answer 76

Thick lens edge too much or too little edge lift inadequate tear volume Inferior riding lens Small amount is ok

Answer 77

Bleph, mebomianitis, meds, inadequate tears