Intra-Operative Cap Repositioning in Small Incision Lenticule Extraction (SMILE) for Enhanced Visual Recovery

ABSTRACT

Purpose: To study the role of intra-operative cap repositioning in acute visual recovery after small incision lenticule extraction (SMILE).

Materials and methods: Ninety-four eyes of 47 patients underwent the SMILE procedure for correction of myopic refractive error. Manifest refraction and visual quality parameters (optical quality analysis system) were evaluated before surgery. The Bowman’s membrane was imaged using a handheld spectral domain optical coherence tomography device. All patients underwent an uneventful SMILE surgery by a single experienced surgeon. Intra-operative cap repositioning was done in the “right” eye of all patients (repositioned group) and the “left” eye of each patient served as controls (non-repositioned group). Visual acuity and optical quality were assessed 1 day and 1 week after surgery.

Results: Bowman’s membrane microdistortions were found in 21.3% of eyes in the repositioned group and 59.57% of the eyes in the non-repositioned group (p = 0.003) on the first day after surgery. Comparison of optical quality parameters was carried out between eyes where repositioning was done and control eyes (with and without microdistortions). On the first day after surgery, the modulation transfer function (MTF) and Strehl’s ratio (SR) were significantly better in the repositioned group when compared with the controls (p = 0.002 and p = 0.003, respectively). Refractive error and lenticule thickness in eyes with microdistortions were similar (p > 0.05) between the two groups indicating other contributors to acute optical quality postoperatively.

Conclusions: Although the refractive error before surgery determines the extent of microdistortions, intra-operative cap repositioning can reduce them, thereby expediting acute visual recovery after SMILE.

KEYWORDS:

• Handheld spectral domain optical coherence tomography
• microdistortions
• repositioning
• small incision lenticule extraction (SMILE)
• visual quality

Acknowledgment

This study was funded in part by Carl Zeiss, Inc., Oberkochen, Germany. Dr. Sinha Roy has received research funding in the area of biomechanical modeling of the eye from Carl Zeiss, Inc., Oberkochen, Germany; Avedro, Inc., Waltham, MA, USA; and Topcon Medical Systems, Inc., Oakland, CA, USA. Dr. Sinha Roy has intellectual property related to computational modeling through Cleveland Clinic Innovations, Cleveland, OH, USA. Dr. Rohit Shetty has received research funding from Allergan, Inc., Irvine, CA, USA. Mathew Kurian Kummelil has received funding from Alcon Laboratories, Inc., Fort Worth, TX, USA; Allergan, Inc.; and Carl Zeiss, Inc. No other author has any financial or proprietary interests to declare.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.