1. Collagen Cross-Linking in Early Keratoconus: Before and After
Austin Schipper, OD
Case History
Topography
Treatment and Management
A 19-year-old Caucasian female was referred for a keratoconus (KCN) evaluation and contact lens fit.
Ocular History:
KCN OS>OD diagnosed four months prior.
Medical History:
Unremarkable with no reported medications
Personal Family and Social History:
No family history of KCN was noted, otherwise unremarkable.
Best corrected spectacle visual acuity:
OD: x /15
OS: x /40
Slit lamp examination:
OD: within normal limits
OS: inferior stromal thinning, mild corneal striae
Pachymetry:
OD: 554 microns
OS: 518 microns
Baseline Topography: July 8, 2016
OD: inferior central steepening K-max D
OS: inferior central steepening K-max D
Figure 1. July 8, 2016 Right eye Figure 2. July 8, 2016 Left eye
Figure 3. July 20, 2017 Right eye Figure 4. July 20, 2017 Left eye
Contact Lens Parameters:
OD: No Lens
OS: -6.25/6.6/8.5 Art Keratoconic System (AKS)
Contact Lens Evaluation:
OD: No Lens 20/15
OS: Three point touch 20/25+1
Due to the mild presentation of KCN, Collagen Cross-Linking (CXL) was discussed with the patient and a referral was made for a CXL consultation. Due to the age of the patient, pachymetry values, and documented progression from topographies taken by referring Optometrist, Epithelium-off CXL was recommended.
Procedure: Epithelium-off (epi-off) CXL
OD: February 6, 2017
OS: December 14, 2016
Repeat Topography: July 20, 2017
OD: inferior central steepening K-max D
OS: inferior central steepening K-max D
Mild progression was noted in the right eye with minimal progression in the left. Following evaluation on July 20, 2017, the habitual lens provided three-point-touch, no parameter changes were required.
Diagnosis and Discussion
Diagnosis and Discussion Continued
Conclusion
Keratoconus (KCN) clinically presents as a bilateral, non-inflammatory, progressive thinning of the cornea beginning at the onset of puberty, and progressing over a period of years.
Historically, patients with KCN have been fit with corneal gas-permeable (GP) lenses until surgery is needed. However, with the treatments available today, patients are able to delay, and in some cases, prevent the need for invasive corneal surgery. Furthermore, access to several modalities no longer limit the patient and practitioner to balancing the awareness of GP lenses with the quality of vision they provide. Once contact lenses are no longer an option, surgery must be considered.
Commonly performed surgical options for KCN consist of intrastromal ring segments, collagen cross-linking (CXL), deep anterior lamellar keratoplasty (DALK), and penetrating keratoplasty (PK). Each surgical option must be carefully evaluated on an individual basis to determine which is likely to provide favorable outcomes. Receiving Food and Drug Administration approval for use in the United States on April 18, 2016, CXL is the newest surgical procedure for progressive KCN available today. Utilizing vitamin B2 (riboflavin) and ultraviolet A (UVA), the cornea is able to increase its rigidity by over 300% and optimistically halt progression of the disease.1 Progressive KCN with pachymetry greater than 400 microns are candidates.
The epithelium-on (epi-on) approach has been shown to be 20-30%2-3 as effective as the epi-off procedure at stiffening the cornea. While epi-off is more effective at increasing corneal stiffness, both procedures have been shown to prevent progressive vision loss in 95% of patients with 80% of patients showing visual acuity improvement from baseline.2
Faster healing time, lower risk of infection, and reduced pain are all benefits described when discussing epi-on CXL.2-3 Patients who do not qualify for epi-off CXL due to pachymetry values less than 400 microns may be candidates for the epi-on procedure. It is important to be aware of both procedures when managing patients who have KCN.
When determining the proper course of treatment for patients with keratoconus it is important to consider all treatment options. In this particular case the patient was newly diagnosed and had adequate unaided vision with documented progression. This is the ideal patient when considering CXL as a treatment option.
Krachmer J, Mannis M, Holland E Cornea. Third edition. China: Mosby Elsevier. Chapter 74, Noninflammatory Ectatic Disorders; p
Rabinowitz Y, Rubinfeld R. May Corneal Collagen Cross-Linking. Cataract and Refractive Surgery Today.
Caporossi et al. Transepithelial corneal collagen crosslinking for progressive keratoconus: 24-month clinical results. J Cataract Refract Surg 2013; 39: