Corneal asphericity changes after implantation of single intracorneal corneal ring segment vs implantation of double intracorneal segments in the cornea for treatment of keratoconus

الملخص EN

Aim : to compare the effect of implantation of intracorneal rings on corneal sphericity between one segment ring and double segment ring implantation in keratoconus eyes.

setting : memorial institute for ophthalmic research methods : this study is retrospective study done on 30 eyes of keratoconus patients between 2019 and 2021.

intracorneal rings were implanted in the cornea for treatment of keratoconus the study was done on two study groups, in group a one ring segment was implanted and in group b two ring segments were implanted.

the choice of the number, thickness and arc length of the rings were done according to kera ring manufacture nomogram.

we studied the corneal sphericity measured by corneal ashericity coefficient (Q value) concluded from pentacam preoperative and 6 month postoperative.

keratometric values, visual acuity and refraction of the patients were also studied preoperatively and 6 month postoperative.

results : the changes in refraction were statistically significant before and after surgery in both groups regarding UCVA and refraction.

comparing both groups regarding sphere and cylinder refraction, we found that there was significant difference in sphere refraction pre and postoperatively (p < 0.001 & 0.009 respectively) and in cylinder refraction preoperatively (p = 0.024).

the changes in Q anterior were significant in both groups.

moreover, the changes in K1, K2, k max and astigmatism values before and after ring implantation were significant in both groups.

comparing the results of K1, K2, k max and Q anterior significant difference was observed between the two groups after surgery while there was significant difference in K1 and K2 before surgery.

conclusion : intracorneal ring segments implantation for treatment of keratoconus either one or two rings change the anterior corneal asphericity approximating the Q anterior value to the ideal Q value (-0.46) and improve the UCVA and the BCVA of patients besides decrease the refractive sphere and cylinder values.

implantation of two rings have higher effect than implantation of one ring on approximating the Q anterior value to ideal.