Evaluation Of Pupi̇l Offset After Collagen Crosslinking In Keratoconus

To analyze the effect of corneal collagen crosslinking (CXL) on pupil offset parameters and relationship between the changes in pupil offset parameters and visual acuity in patients with  progressive keratoconus.

Yıldırım Beyazıt University Ataturk Training and Research Hospital, Department of Ophthalmology, Ankara, Turkey

In this restrospective study 104 eyes of 93 patients (37 female, 56 men) who undergone corneal CXL  surgery for progressive keratoconus were analyzed. Pupillary offset parameters were measured by corneal topography (Sirius, CSO, Italy) preoperative and  postoperative  2^nd year. The distance of the pupillary center relative to the Line of Sight (Los) was calculated in millimeters along the horizontal x-axes (x-offset) and vertical y-axes (y-offset). The total pupillary offset (t) values were calculated according to the Pythagorean equation (t² = x²+y²).  Parameters were compared with 70 eyes of 70 healty controls. Furthermore relationship between pupillary offset parameters and best corrected visual acuity (BCVA) were analyzed.

 

In keratoconus patients before CXL pupil centre was superonasally located when compared to control group (p<0.001). After corneal CXL pupil centre was more centrally relocated in vertical axes (p=0.008) and more temporaly relocated in horizontal axes (p=0.531) and became close to healty control group. 

Postoperative 2^nd year there was a positive correlation between horizontal pupil offset and BCVA (p=0.003 / r=0.306). Although there were negative correlation between total and vertical pupil offset and BCVA (p=0.009 / r= -0.268 and p=0.015 / r= -0.248). 

In keratoconus patients pupil centre was more superonasally located than control group. After CXL treatment pupil centre was relocated which was closer to control group. After CXL as pupil offset parameters were declined  BCVA levels were increased.