Corneal thickness, residual stromal thickness, and its effect on opaque bubble layer in small-incision lenticule extraction

Abstract

The results suggest that OBL formation during SMILE surgery is more likely in eyes with a thicker cornea. CCT and RST can be considered independent risk factors for OBL formation. Although this phenomenon may disturb the surgical procedure, it is unlikely to affect the postoperative visual outcome.

Possible risk factors of opaque bubble layer and its effect on high-order aberrations after small incision Lenticule extraction

“…The OBL area was positively correlated with those parameters, but not the CCT. Previous studies found that a thicker cornea was a risk factor for OBL formation in both FS-LASIK and SMILE surgeries, but the correlation was relatively weak when the CCT was below 550 um ( 13 ). A majority of the cases in our study had a CCT of less than 550 um, which could explain why the OBL area did not correlate with CCT.…”

“…RST is another risk factor for OBL development in SMILE surgery. Ma et al found that when RST increased 1 um, the risk of OBL formation increased 3% ( 13 ). Our study also found that OBL tended to develop when there was a thicker RST and thinner cap thickness.…”

“…In addition, corneal biomechanics may also play a role in the OBL formation. A previous study reported that higher corneal resistance factor (CRF) and cornea hysteresis (CH) values resulted in more severe OBL ( 5 , 21 ). The anterior part of the cornea has a stronger biomechanical strength, which could explain why OBL tended to develop if the cap thickness was thin.…”

“…Although OBL formation may cause difficulty during SMILE surgery, OBL does not affect the long-term visual acuity and refraction ( 13 ). Visual perception is a complex psychophysical process, and the visual system adapts to changes in the environment, as well as the type of astigmatism, thereby influencing visual quality ( 14 , 15 ).…”

Effect of corneal flap thickness on opaque bubble layer formation in Visumax FS-LASIK using GEE analysis

“…The application of femtosecond laser in flap creation greatly improves the safety and predictability of LASIK; however, complications may occur. The corneal stromal plane was separated by ionization and photodisruption of the femtosecond laser, and the OBL formed was a unique complication of femtosecond laser [ 2 , 9 ]. OBL may disturb complete flap creation and affect subsequent flap lifting and excimer laser eye tracking.…”