Corneal Imaging and Densitometry Measurements in Juvenile and Adult Keratoconus Patients to Evaluate Disease Progression and Treatment Effects After Corneal Cross-Linking

Purpose: In this study densitometry software for the Oculus Pentacam was used to investigate the treatment outcomes of corneal cross linking (CXL) in adult and juvenile keratoconus (KCN) patients. Densitometry measurements were taken before and after treatment and followed up for one year. Methods: A comparative study was carried out at Manchester Royal Eye Hospital. Corneal densitometry measurements collected before and after CXL treatment for 32 eyes from KC patients, aged between 12 and 39, were divided to 2 groups 13-18 years (juvenile group) and 19-39 years (adult group) and analysed and compared to pre and post treatment at 3, 6 and 12 months for each group and between both groups. Results: Analysis of densitometry measurements found higher corneal densitometry after CXL which peaks at three months post treatment in both groups. There was significant diversity in corneal densitometry measurements in the stromal zone 0-2 and 2-6 mm for all layers except the posterior layer for both groups (P<0.05). Significantly increased densitometry value was found higher in the juvenile group at six months in the central (P=0.006) and posterior (P=0.004) layers for zone 0-2 mm. The same layers differed significantly also in the 2-6 mm zone in all layers (P=0.01). One year post treatment the same significant increased densitometry level was seen in the juvenile group in the 0-2 mm zone of the central (P=0.007) and posterior layers (P=0.01), as was the 2-6 mm zone (P=0.04). However, no significant difference was found between pre and post treatment for best corrected visual acuity (BCVA), central corneal thickness (CCT) and thinnest area between both groups. A significant difference was found between pre and post treatment for best corrected visual acuity (BCVA), in the adult group at 6 and 12 months post-treatment from pre-treatment (P=0.02, P=0.16) respectively. Conclusion: Corneal clarity post CXL treatment in the juvenile group differed significantly from the adult group. Both groups showed increased haze at 3 months post treatment but the adults showed improvement over the next 9 months. In contrast, the juvenile group showed higher densitometry readings at both 6 and 12 months post treatment in comparison to adult group. The reasons for this remain unclear.