Collagen Shrinkage and Crosslinking Procedures

Question 1

Conductive Keratoplasty - treatment of what

Answer 1

for treatment of presbyopia in the nondominant eye of a patient with an endpoint of –1.00 to –2.00 D. In cases of overcorrected myopic LASIK and myopic photorefractive keratectomy (PRK), CK can be used to correct hyperopia. CK may also be used to treat keratoconus and post-LASIK ectasia.

Question 2

Conductive Keratoplasty - mechanism

Answer 2

The nonablative, collagen-shrinking effect of CK is based on the delivery of radiofrequency energy through a fine conducting tip that is inserted into the peripheral corneal stroma. The shortening of the collagen fibrils creates a band of tightening and flattening in the periphery that increases the relative curvature of the central cornea

Question 3

Conductive Keratoplasty - for whom not

Answer 3

not advised for use in patients who have undergone radial keratotomy

Question 4

Conductive Keratoplasty - disadvantage

Answer 4

long-term follow-up has revealed regression and/or lack of adequate effect with CK.

Question 5

CCL - minimal thickness of cornea and what to do if whinner

Answer 5

minimal corneal thickness of 400 μm. Thinner corneas may be thickened temporarily with application of a hypotonic riboflavin formulation prior to UVA treatment

Question 6

CCL - what does riboflavin

Answer 6

serves as a source for the generation of singlet oxygen and superoxide anion free radicals. In the presence of riboflavin, approximately 95% of the UVA light irradiance is absorbed in the anterior 300 μm of the corneal stroma

Question 7

CCL - main goal

Answer 7

Although there may also be a slight flattening of the cornea, the most important effect of CCL is to stabilize the corneal curvature. There is no significant change in the refractive index or the clarity of the cornea

Question 8

CCL - Dresden protocol

Answer 8

riboflavin solution is continually applied to the de-epithelialized cornea for 30 minutes, and the riboflavin is then activated by illumination of the cornea with UVA light for 30 minutes, during which time application of the riboflavin solution continues

Question 9

CCL - % of patients with improvement of vision

Answer 9

65% had an improvement in visual acuity

Question 10

CCL - contraindications

Answer 10

corneal thickness of less than 400 μm, prior herpetic infection, severe corneal scarring or opacification, history of poor epithelial wound healing, severe ocular surface disease, autoimmune disorders

Question 11

CCL - disadvantage of epithelial debridement

Answer 11

possible delayed epithelial healing, infection, stromal haze, and corneal melting

Question 12

CCL - epi on or epi off has slightly lower efficacy

Answer 12

epi on

Question 13

That can enhance riboflavin’s penetration?

Answer 13

benzalkonium chloride, trometamol, and ethylenediaminetetraacetic acid, iontophoresis and partial disruption of the superficial epithelial layers

Question 14

Athens protocol

Answer 14

Same-day PRK followed by CCL

Question 15

triple procedure

Answer 15

CCL combined with topography-guided PRK to regularize the corneal shape and the implantation of a phakic intraocular to optimize the refraction

Question 16

Complications of CCL

Answer 16

delayed epithelial healing, corneal haze (which may be visually significant), decreased corneal sensitivity, infectious keratitis, persistent corneal edema, and endothelial cell damage