Risk Factors Of Progression In Subclinical Keratoconus

To  evaluate the risk factors of progression in subclinical keratoconus eyes.

Wuhan Aier Hankou Eye Hospital, Wuhan University, Wuhan, China.

The data of 43 eyes of 43 patients (6 females, 37males) diagnosed as subclinical keratoconus（SKC) and followed up for at least 12 months were evaluated. SKC was defined as the fellow eye of diagnosed  keratoconus, with normal slit lamp evaluation and normal topography,  CDVA better than 1.0 and Kmax less than 47.2D. The information of Pentacam HR and Corvis ST  at the first present and  the last follow-up were analyzed. Progression of SKC were suspected as Delta Kmax( last- first )≥ 1.0D, combined with loss of BCVA ≥2 snellen lines, or Delta Back Elevation (last-first)    ≥ 5 um. Risk factors of SKC progression were analyzed.

Six of 43(14%) SKC eyes were suspected as progression in an average 31.9 mos follow-up. All of these 6 patients were younger than 21 years old. TBI at the first visit was higher in the progressive eyes than in the stable eyes (0.81±0.28 VS  0.36±0.30, P=0.008), and BAD D at the first visit was higher in the progressive eyes than in the stable eyes (2.08±0.40 VS  1.53±0.68, P=0.042). Corneal biomechanical parameters A2 Velocity and PRFI had statistical significance between progrsssive and stable groups (P=0.042, P=0.017). 3 of 6 progression eyes were with SSI less than 0.75, while no eyes in stable condition with SSI less than 0.75.  Other data showed  no statistically significance between progressive and stable SKC eyes.

High TBI and BAD D, young age and low SSI  might be the risk factors of progression in SKC eyes. In these patients more caution and longer follow-up should be given.