PMC6582852_01
(a) Topography pretreatment. (b) Ferrara nomogram. (c) First intrastromal ring position. (d) KeraRing nomogram position. (e) One-month postimplantation ring position. (f) One-year postmodification ring position.
CRIOPM2019-7151849.001.jpg
PMC6582852_01_CRIOPM2019-7151849.001.jpg
fig1
In his left eye, his UCVA was 20/25 with -0.25-0.50 x 75  and BCVA of 20/20 (Figure 1(a)). Belo Horizonte, Brazil) used in this study was a 160  segment ring made of polymethyl methacrylate (PMMA) implanted in the corneal tunnel (Figure 1(c)). Both ICRS nomograms, Ferrara and KeraRing, indicated different ring position (Figures 1(b)-1(d)), so a temporal 160 /200-micron ring was utilized. However, his RMS improved from 14.750 um to 10.346 um (Figure 1(e)). According to the postoperative keratometric Scheimpflug map, the ring was moved 50 degrees counterclockwise according to the topographic results (Figure 1(d)).
PMC6582852_02
(a) Topography pretreatment. (b) Ferrara nomogram. (c) First intrastromal ring position. (d) KeraRing nomogram position. (e) One-month postimplantation ring position. (f) One-year postmodification ring position.
CRIOPM2019-7151849.002.jpg
PMC6582852_02_CRIOPM2019-7151849.002.jpg
fig2
Keratoconus was diagnosed in both eyes; femto ICRS was indicated for the right eye and follow-up for the left eye (Figure 2(a)). The two nomograms proposed, KeraRing and Ferrara, indicated different ring positions (Figures 2(b)-2(d)), so a temporal 160 /150-micron ring (Figure 2(c)) was utilized. Two months later, the patient's UCVA was 20/150, his BCVA was 20/40, and his manifest refraction was -1.00-2.00 x 50 , indicating a loss of one line of vision (Figure 2(e)). Therefore, the ring was moved 45 degrees counterclockwise in the tunnel according to the keratometric Scheimpflug map (Figure 2(d)).