Unintended initial dissection of the posterior plane (UIDPP) during small incision lenticule extraction (SMILE) surgery significantly increases the operation time, according to a study in BMC Ophthalmology. However, researchers noted that UIDPP did not affect long-term visual recovery after the procedure.   

Investigators conducted a retrospective study involving 66 eyes of 66 patients with myopia (36 women, 30 men). The mean age of the patients was 23.6±4.6 years (range 17-37 years). Participants underwent SMILE at the EYE & ENT Hospital of Fudan University between July 2015 and September 2017. Based on the surgery video, the operating eyes were assigned to the normal and UIDPP groups according to the presence or absence of UIDPP signs during the procedure. The researchers further separated the UIDPP group into early and late detection based on the complete dissection of the lenticule posterior plane. They also collected patient demographic data including preoperative evaluation, operation time and postoperative outcomes.   

Of the 66 eyes who underwent SMILE, 24 eyes experienced UIDPP (13 eyes in the early group, 11 eyes in the late group). The optical zone was smaller (median 6.5 vs. 6.6, P =.007), and the surgery time was longer (median, 189.5 vs 91.0 s, P <.001) in the UIDPP group compared with the normal group. There were significant differences in surgery time between the late detection group and early detection group (median, 489.0 vs 139.0 s, P <.05), as well as between the late detection group and normal group (median 489.0 vs 91.0 s, P <.05). While the optical zone was different solely between the late detection and normal groups (median, 6.5 vs 6.6, P <.05). At the 1 year follow-up, 87.5% of eyes had uncorrected distance visual acuity better than or equal to 20/20, and 75% of eyes were within ±0.5 D of the intended refractive target. The investigators reported that 1 eye lost 1 Snellen line. 

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Study limitations include the small sample size, single-center design, retrospective nature, and only 1 surgeon performed all the operations. 

“The difficult lenticule dissection and removal caused by UIDPP during SMILE are the most important conditions for refractive procedure surgeons, especially novices, who need to avoid,” according to the study authors. “For the procedure time of SMILE, the time for lenticule dissection and removal is important.” The study also says identifying UIDPP early can prevent prolong SMILE surgery time. 


Zheng K, Han Y, Wang J, Han T, Zhou X. Impact of unintended initial dissection of the posterior plane during SMILE surgery on surgery time and visual outcomes. BMC Ophthalmol. Published online March 8, 2022. doi:10.1186/s12886-022-02333-x