Untreated keratoconus patients who are young or have steepest keratometry (Max-K) may be at increased risk of disease progression, new research published online in the British Journal of Ophthalmology suggests.
For every 1.00D steeper Kmax, researchers noted a 7% and 3% greater risk of worsening VA and corneal thinning, respectively. For each “one year younger,” the study found a 4% and 2% greater likelihood of Kmax steepening and thinning of the cornea, respectively.
The large-scale investigation enrolled 3,994 untreated eyes of 2,283 patients from 34 centers across Australia, New Zealand, Italy and Spain. Investigators classified patients as progressors or stable for each of the study’s clinical parameters: visual acuity, Kmax and thinnest corneal thickness. The paper’s primary outcome was the proportion of eyes that had sustained progression in these areas over three years.
The amount of eyes with VA, Kmax and thinnest corneal thickness progression at one year was approximately 3%, 7% and 3%, respectively.
Specifically, researchers noted a trend of VA loss in participants who had higher VA loss at baseline (hazard ratio; HR: 1.15 per logMAR line increase in VA) and steeper baseline Kmax (HR: 1.07 per 1D increase). Additionally, individuals who were younger at the study’s onset showed a trend of Max-K steepening (HR: 0.96 per year older).
Thinnest corneal thickness thinning also appeared to be linked to thicker baseline thinnest corneal thickness (HR:1.08 per 10µm increase in thickness), steeper baseline Kmax (HR: 1.03 per 1.00D increase) and younger baseline age (HR: 0.98 per year younger).
The study’s findings align with the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) investigation that was pivotal in examining the natural history of keratoconus, the researchers noted.2 In the CLEK study cohort, 19% of eyes progressed by 10 or more BCVA letters after seven years of follow-up.2
However, the current study’s thinnest corneal thickness progression results differ from other similar investigations.3 The authors found sustained thinnest corneal thickness thinning of 20µm or greater occurred in roughly 3% of eyes at one year, while previous studies reported higher progression in children with baseline thickness of less than 450µm.3
In light of the paper’s findings, the authors recommend that patients with better VA, thicker thinnest corneal thickness and younger age at baseline are followed up more closely as they have a greater risk of worsening VA and corneal thinning.
“Furthermore, patients with steeper Kmax and younger age at baseline should undergo particularly close follow-up given these patients are at greater risk of deterioration in two clinical parameters. These at-risk groups may also benefit from lower thresholds for early corneal crosslinking to prevent irreversible visual loss,” researchers wrote in their paper.
1. Ferdi A, Nguyen V, Kandel H, et al. Predictors of progression in untreated keratoconus: a Save Sight Keratoconus Registry study. Br J Ophthalmol. March 30, 2021. [Epub ahead of print].
2. Zadnik K, Barr JT, Edrington TB, et al. Baseline findings in the Collaborative longitudinal evaluation of keratoconus (CLEK) study. Invest Ophthalmol Vis Sci 1998;39(13):2537–46.
3. Hamilton A, Wong S, Carley F, et al. Tomographic indices as possible risk factors for progression in pediatric keratoconus. J AAPOS. 2016;20(6):523–6.