Evidence Supports Long-term Efficacy of Collagen Crosslinking
Corneal collagen crosslinking (CXL) may be effective in managing keratoconus for longer than two years, according to a recent study in the journal Cornea. A possible reversal of CXL effects after four years was also discovered.

The study followed 377 eyes in pediatric patients ages eight to 18, all of whom had progressive keratoconus and underwent CXL. Of the eyes tracked, 194 had follow-ups more than two years post-treatment, the results of which show a significant improvement in mean spectacle-corrected distance visual acuity (CDVA), a reduction in mean topographic astigmatism, flattening of keratometry (Kmax) and corneal thinning of 31.1 ± 36.0μm.

Despite these promising results, the study also revealed the effects of CXL reversed after four years post-treatment in some eyes.

The researchers noted stabilization or flattening of Kmax in 85% of eyes at two years, which dropped to 76% after four years. CDVA improved in 80.1% of eyes at two years, but only in 69.1% at four years. After four years, 24% showed steepening of the cornea and 30.9% showed reduced visual acuity, suggesting possible progression of the disease after four years.

Some note that these findings are not statistically significant in the current study, however. “Confounding factors like thinner corneal pachymetry expected after CXL further make it challenging to diagnose regression at its immediate resurgence,” says Clark Chang, OD, director of Clinical Services at TLC Vision and director of Cornea Specialty Lenses at Wills Eye Hospital -Cornea Service, Philadelphia, PA. “Therefore, it is important to minimize or eliminate extrinsic factors that can exert mechanical strain on the ocular surface, which presumably can destabilize therapeutic effects conferred by CXL.”

Clinicians must remain vigilant in managing ocular comorbidities such as dry eye and atopic or allergic conditions, Dr. Chang says, as well as educate patients about both the risks of long-term regression and the importance of compliance with clinical monitoring to detect the potential need for retreatment.

The study also found that 17.1% of eyes in the study presented topographic coupling effects—in which flattening of one meridian is accompanied by steepening of the orthogonal meridian—suggesting a compensatory biomechanical response. “If we can control and maximize such coupling effects, then better visual outcome after CXL may be achieved,” Dr. Chang says. “Thus, it is essential for future investigations to identify patient variables associated with such topographic coupling events, as well as determine clinical characteristics that may better predict the duration of CXL stabilization effects in different patient subgroups.”

1. Padmanabhan P, Reddi SR, Rajagopal R, et al. Corneal collagen cross-linking for keratoconus in pediatric patients—long-term results. Cornea. 2017;36(2):138-143.

In Brief
Meibomian gland damage may be reversible in patients with meibomian gland dysfunction (MGD), a recent study in Cornea suggests.1 The key treatment used in the study was an artificial lubricant four times a day, coupled with eyelid hygiene once a day. Researchers found the dual approach resulted in a 5.4% decrease in MG dropout in upper eyelids and a 4.6% decrease of MG dropout in lower eyelids, as well as improvement across all clinical indices for study participants who heeded the instructions to take care of eyelid hygiene. Participants who ignored doctors’ orders did not experience the same improvement, save for some in the ocular surface disease index.

1. Yin Y, Gong L. Reversibility of gland dropout and significance of eyelid hygiene treatment in meibomian gland dysfunction. Cornea. October 14, 2016. [Epub ahead of print].

The first Descemet’s membrane endothelial keratoplasty (DMEK) patient recently presented for a 10-year follow up, and the clinical outcomes are encouraging, according to a recent report.1 The patient showed all the short- and long-term characteristics of this endothelial keratoplasty technique, including outstanding patient satisfaction, quick visual recovery, low incidence of complications and graft longevity. Best spectacle-corrected visual acuity in both eyes remained stable from the initial postoperative improvements.

While this case covers just one patient’s outcome, results such as these may show the potential for DMEK to be adopted as the preferred treatment option for corneal endothelial disorders in the future.

1. Baydoun B, Müller T, Lavy I. Ten-year clinical outcome of the first patient undergoing Descemet membrane endothelial keratoplasty. Cornea. December 8, 2016. [Epub ahead of print].