This article is more than 5 years old. Information may no longer be current.
Preoperative factors affect cross-linking success in pediatric keratoconus patients
Cone location and corneal thickness may determine treatment outcomes in these patients.
Click Here to Manage Email Alerts
A single-center retrospective study identified several preoperative factors in pediatric patients with keratoconus that directly affected the success of corneal collagen cross-linking.
Pediatric keratoconus patients with baseline paracentral cone location and/or thinner corneas tend to have the worst outcomes at 2 years after corneal collagen cross-linking, Ozge Sarac, MD, told Ocular Surgery News.
“Pediatric age is a negative prognostic factor for having keratoconus. Waiting for confirmation of progression is not essential in pediatric keratoconus patients, and CXL should be performed as soon as a diagnosis of keratoconus has been made. Age, gender, preoperative visual acuity and keratometry do not seem to affect 2-year outcomes of CXL treatment in pediatric patients. Preoperative corneal thickness and topographic cone location are the sole predictors of the keratometry outcomes 2 years after CXL in pediatric keratoconus patients,” Sarac said.
Patients and characteristics
The study included 72 eyes of 52 consecutive patients younger than age 18 years. All patients had keratoconus, and their outcomes after cross-linking were evaluated at a 2-year follow-up. Researchers evaluated several factors, including age, sex, topographic cone location, maximum keratometry and corneal thickness at the thinnest point to evaluate possible associations between outcomes.
Cross-linking outcomes were determined by maximum keratometry.
The researchers assessed the baseline clinical and topographical patient factors to determine the characteristics that predict the outcomes of cross-linking. Subgroup analyses conducted to evaluate the associations between preoperative patient characteristics and outcomes of cross-linking treatment in terms of maximum keratometry included age younger than 14 years or 14 years and older, sex, uncorrected visual acuity and corrected distance visual acuity of less than 0.8 logMAR or 0.8 logMAR and greater, central or paracentral topographic cone location, maximum keratometry of less than 54 D or 54 D and greater, and corneal thickness at the thinnest point of less than 450 µm or 450µm and greater.
Factors for progression
Keratoconus was more likely to progress in patients with corneal thickness at the thinnest point of less than 450 µm (P = .008) and/or those with paracentral cones (P = .023).
However, baseline uncorrected and corrected distance visual acuities, sex, age and maximum keratometry did not have any significant effect on progression 2 years after treatment, Sarac noted.
“According to our findings, nearly half of the pediatric patients with paracentral cones or corneas thinner than 450 µm have progression of their keratoconus 2 years after CXL. Knowing that these patients do not respond as well to CXL treatment will force clinicians to find answers to the questions such as, ‘Should we treat pediatric keratoconus patients with paracentral cones or with thin corneas?’ ‘Should we treat them more frequently or more aggressively?’ Pediatric keratoconus patients who have no CXL have a progression rate of 88%. Therefore, in our opinion, CXL should be performed in pediatric keratoconus patients with paracentral cones and/or those with corneas thinner than 450 µm because it is more effective than having no CXL,” she said.
Patients with thinner corneas may have more serious corneal pathology, and the factors for progression of keratoconus may be stronger in these types of patients. The stabilizing effects of cross-linking in pediatric patients with thin corneas may have been overcome by the driving factors of keratoconus, Sarac said.
“UV light used during CXL treatment is delivered in a flat, perpendicular emission plane. Therefore, peripherally located cones are exposed to obliquely incident (and less intensive) UV light rays than the central cones. Supporting this hypothesis, we demonstrated in our study that eyes with paracentrally located cones progressed at twice the rate as eyes with centrally located cones,” she said. – by Robert Linnehan
- Reference:
- Sarac O, et al. Cornea. 2016;doi:10.1097/ICO.0000000000001051.
- For more information:
- Ozge Sarac, MD, can be reached at Department of Ophthalmology, Ankara Ataturk Training and Research Hospital, Bilkent, Ankara, Turkey 06810; email: drozgesarac@gmail.com.
Disclosure: Sarac reports no relevant financial disclosures.