Outcome Of Customized Corneal Collagen Crosslinking For Keratoconus Patients In Oman – Up To 3 Years Results

Keratoconus is found to have a higher prevalence in the Sultanate of Oman affecting the adolescent and young adults, a time where the visual demand is very high for education and early career. The impact on the quality of life is also a quite significant. Hence we carried out many research works on prevalence of keratoconus in Oman and application of Customized Crosslinking as a novel treatment modality.

The analysis of follow up data has shown that Customized Crosslinking can be safely used in patients with progressive keratoconus with good flattening effect and visual outcome. 

This paper is presented to report the outcome of customized corneal collagen crosslinking for keratoconus patients in Oman after 3 years follow up period.

This prospective study was carried out at the Ophthalmology Center, MOD-hospital, Muscat, Oman  with initial 1 year follow up period starting from 2^nd September 2018 and later extended to 3 years to assess the long term outcome.

Total of 54 eyes were treated. 1-year follow up data was available in 48 eyes for analysis but 3-year follow-up data was available in 20 eyes only. Hence an overall analysis of 1-year data and individual analysis of 3-year data was carried out.

Keratoconus patients in the age group of 12-30 with documented progression were included in the study. Epithelial ablation was done over the specific targeted treatment area and corneal collagen  crosslinking was carried out with application of  Riboflavin followed by UVA light. The treatment area and energy levels were customized according to the topographic findings.

Continuous illumination was used with an energy fluence of 30 mW/cm². Total energy levels were ranged from 5.4 J/cm² up to 10 J/cm² with the highest energy being to the center.

Clinical evaluation included uncorrected distance visual acuity (UCVA), corrected distance visual acuity(BCVA), corneal topography, pachymetry and K-reading.

After 3 years follow up, each of the 20 eyes were compared with their achievement at 1 year follow up.19 eyes (95%) had further improvement in UCVA up to 2 lines or remained stable while 1 eye (5%) showed further deterioration of 1 line. 5 (25%) eyes showed further improvement of BCVA from 1 to 3 lines. All the other 15 eyes (75%) had maintained the BCVA same as 1 year follow up visit. Considering the corneal steepness; 19(95%) eyes showed further reduction or stability in Kmax while 1 eye (5%) showed further steepening of more than 1D. Change in the Topographical Keratoconus Classification(TKC); all 20 eyes (100%) maintained the TKC stage as same as 1 year follow up.

Epithelium-off customized corneal collagen crosslinking was safe and effective in stabilizing the progression of keratoconus by 12 months for most patients in this study group. Final results of this novel application of collagen cross-linking shows that almost all patients who have completed 3 years follow up period have maintained or further improved their visual function. These long term results are encouraging and data in larger studies would give us more information. Studies using Epithelium-off customized corneal collagen crosslinking with pulsed illumination and higher dose UVA may further inform treatment parameter efficacy.