Cross-linking may help avoid corneal transplant surgery in advanced keratoconus
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A 54-year-old man was referred in late 2014 for a consultation for corneal transplant surgery in the left eye.
The patient had been diagnosed with keratoconus a few years earlier. His optometrist had fit him in rigid gas permeable contact lenses, but he was unable to tolerate them, given the difficulty of attaining a proper fit. A few years before we saw him, the patient was correctable to 20/25 in the right eye and 20/50 in the left eye in glasses but had recently complained of worsening vision.
Source: Kenneth A. Beckman, MD, FACS, and Alexander J. Luna
Upon examination, best corrected visual acuity with glasses was 20/150 in the left eye. Topography revealed a thin cornea with a steep maximum keratometry (Kmax) of 61 D in the left eye (Figure 1). The right eye was also keratoconic but much less severe at that time. Although we did not have any prior topographies, the change in refractive error consistent with a myopic shift, along with his other subjective symptoms, was indicative of keratoconus progression.
Keratoconus decreases vision in two ways: distortion and obstruction. Distortion (irregular astigmatism) is typically correctable with a scleral lens. Obstruction (central scarring) may not correct if the scar is significant. This patient was fortunate that, despite the severe cone, he did not have any significant central scarring obstructing his vision; his vision loss was purely due to distortion from the irregular astigmatism.
Two-step approach
We could certainly make an argument that this patient with advanced keratoconus was a good candidate for corneal transplant surgery. With a transplant, we may have been able to achieve BCVA of 20/20 or close to that. However, transplant surgery involves an extended healing time, chronic use of topical medications, increased risk of developing glaucoma or cataract, risks to the wound in the case of future trauma to the eye, and the risk of graft rejection or failure. The younger the patient, the more likely they are to need a repeat graft during their lifetime. In short, because of the long-term morbidities associated with transplantation, I believe it is always best to avoid or delay a graft when possible.
In this patient, we opted for a two-step approach to corneal stabilization and visual rehabilitation instead. First, epi-off corneal collagen cross-linking was performed with the iLink system (Glaukos) to stabilize the cornea against further progression. While we typically see the most rapid and significant progression of keratoconus before age 40 years, older patients can still progress, albeit more slowly. Our motto is to treat the corneal progression, not the age. This patient’s worsening acuity and refractive error, even in his 50s, showed that he was still progressing.
After his 1-month post-iLink follow-up appointment, we referred the patient to an optometrist who could fit him in scleral contact lenses. Because there was no visually significant central scar, we anticipated that his vision would improve greatly with a scleral lens.
Results
This patient did well with this approach. Eighteen months later, his Kmax had decreased to 57.7 D in the left eye, and an Oculus Pentacam difference map showed significant flattening of the cone in that eye (Figure 2). BCVA had improved from 20/150 to 20/40 with glasses and 20/20 with scleral lenses. The patient was happy with his level of visual function. Two years later, 4 years after cross-linking, the cornea and BCVA remained stable (Figure 3). He ultimately underwent the same treatment in the right eye, as well.
In this case, the patient was able to avoid all the risks and long-term morbidity of corneal transplant surgery by undergoing cross-linking with scleral lens fitting. This approach bought him more time and does not preclude a future transplant, if needed, to improve vision. In our opinion, any patient with advanced keratoconus deserves an opportunity to stabilize the cornea with cross-linking and to have a scleral lens fit before proceeding with corneal transplant surgery.
- References:
- Gokul A, et al. Br J Ophthalmol. 2017;doi:10.1136/bjophthalmol-2016-308682.
- Kelly TL, et al. Arch Ophthalmol. 2011;doi:10.1001/archophthalmol.2011.7.
- McMahon TT, et al. Cornea. 2006;doi:10.1097/01.ico.0000178728.57435.df.
- For more information:
- Kenneth A. Beckman, MD, FACS, can be reached at Comprehensive EyeCare of Central Ohio, 450 Alkyre Run Drive #100, Westerville, OH 43082; email: kenbeckman22@aol.com.
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