Flattening of cone in various topographic cone locations in relation with preoperative maximum keratometry in keratoconus: 12 months outcomes

Session Details

Session Title: Cornea & Miscellaneous
Session Date/Time: Saturday 22/02/2020 | 08:30-11:10
Paper Time: 08:36
Venue: Auditorium des Ministres.

First Author: Z.Ashena UK
Co Author(s): S. Qureshi  M. Nanavaty              

Abstract Details

Purpose:

To assess the relationship between the flattening of cone in various topographic cone locations in relation to preoperative maximum keratometry (Kmax) in keratoconus at 12 months following epithelium-off corneal crosslinking (CXL).

Setting:

Sussex Eye Hospital, Brighton, United Kingdom

Methods:

110 eyes (110 patients) that underwent epithelium-off CXL between 2014 and 2018 were included in this study. Cone locations of central (K max within the central 3mm), paracentral (K max within 3-5mm) and peripheral (K max outside the central 5mm) were defined based on preoperative X and Y coordinates of the Kmax on the Schiempflug tomography. Anterior and posterior corneal preoperative Kmax were compared with postoperative Kmax at 12 months within and between the three subgroups. Relationship between the amount of flattening of cones in various cone locations and the amount of preoperative Kmax was assessed.

Results:

Fifty-one percent, 33% and 16% of patients had central, paracentral and peripheral cones respectively.  Comparing the three subgroups, anterior Kmax significantly flattened in central cone compared to paracentral and peripheral cones [1.91+/-2.05, 0.37+/-1.62, 0.02+/-1.29 (p=0.004)], but there was no significant difference in the posterior Kmax in any subgroups [0.04+/-0.16, -0.05+/-0.27, -0.8+/-0.54 (p=0.95)]. Comparing pre and postoperative anterior Kmax, central cones significantly flattened by 1.91 +/-2.05 (p=0.0002) compared to paracentral (p=0.005) and peripheral (p=0.01) cones. No significant flattening was noted in posterior Kmax in any groups. Positive correlation exists between the preoperative Kmax and flattening for the study sample (r2=0.11, p=0.01).

Conclusions:

Epithelium-off CXL has significant flattening effect on central cones, compared to paracentral and peripheral cones in progressive keratoconus. It did not, however, change the posterior K max significantly 1 year postoperatively. Variation in anterior and posterior corneal stromal histology is likely to be responsible for this change. There was a positive relationship between the amount of preoperative Kmax and flattening effect of CXL in our study.

Financial Disclosure: