OUTCOME OF CUSTOMIZED CORNEAL COLLAGEN CROSSLINKING (CURV) FOR KERATOCONUS PATIENTS IN OMAN – UP TO 3 YEARS RESULTS

To report the outcome of customized corneal collagen crosslinking for keratoconus patients in Oman over 3 years follow up period

This prospective study was planned to carry 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

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 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 30mW/cm². Total energy levels were ranged from 5.4J/cm²up to 10J/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.

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.

At the 1 year follow up assessment of 48 eyes; 89% had improved UCVA from 1 line (LogMAR) to 6 lines or remained stable. 95% had improved BCVA from 1 line to 5 lines or remained stable. Considering the K-max 61% had shown 1 to 6 Diopter(D) flattening while 39% had progressed further but not more than 1D. Considering the Topographic Keratoconus Classification(TKC), 40% had improvement in the TKC stage while the rest remained same.

After 3 years, each of the 20 eyes were compared with their findings at 1 year follow up visit.

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 eyes(25%) 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 eyes(95%) 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 maintained the TKC stage as same as 1 year follow up.

Epithelium-off customized corneal collagen crosslinking (Epi-Off CuRV)  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 show that almost all patients who have completed 3 years follow up 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 Epi-Off CuRV with pulsed, higher dose UVA may further inform treatment parameter efficacy.