The Influence of Axial Length on Visual Quality Following SMILE Surgery in Patients with High Myopia

This retrospective study aimed to investigate the subjective and objective visual outcomes following Small Incision Lenticule Extraction (SMILE) surgery in high myopic patients with varying axial lengths (AL).

Study Overview

• Status: Completed
• Conditions: High Myopia; Visual Quality; Axial Length
• Intervention / Treatment: Other: This study does not involve any interventions

Detailed Description

The study enrolled 113 highly myopic patients (202 eyes) who underwent SMILE surgery at Shanghai's Tenth People's Hospital. Patients were classified into three groups based on the axial length before surgery: Group A (AL < 26 mm, 62 eyes), Group B (26 mm ≤ AL < 27 mm, 88 eyes), and Group C (AL ≥ 27 mm, 52 eyes). Preoperative and postoperative evaluations included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), equivalent spherical error(SE), and corneal high order aberration. Subjective visual quality was assessed using the Quality of Vision (QoV) questionnaire.

• Study Type: Observational
• Enrollment (Actual): 113

Contacts and Locations

Study Locations

• China
  • Shanghai
    • Shanghai, Shanghai, China, 200000
      • Shanghai Tenth People's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

A total of 113 high myopic patients (202 eyes) of Shanghai's Tenth People's Hospital were enroled in this prospective, non-randomized study conducted from July 2021 to September 2023.

Description

Inclusion Criteria:

• manifest refraction spherical equivalent refraction exceeding -6.00D;
• stable myopia for a duration of at least 2 years;
• corrected distance visual acuity of at least 20/25;
• annual myopic spherical equivalent increment less than - 0.50 D.

Exclusion Criteria:

• a history of moderate to severe dry eye as well as any ocular or systemic disease.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
AL < 26 mm; high myopic patients with axial lengths < 26 mm	Other: This study does not involve any interventions; This study does not involve any interventions
26 mm ≤ AL < 27 mm; high myopic patients with 26 mm ≤ axial lengths < 27 mm	Other: This study does not involve any interventions; This study does not involve any interventions
AL ≥ 27 mm; high myopic patients with axial lengths ≥ 27 mm	Other: This study does not involve any interventions; This study does not involve any interventions

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Subjective visual quality	The quality of vision (QOV) questionnaire consists of (i) symptom frequency, (ii) severity, and (iii) bothersomeness for (a) glare, (b) halo, (c) starbursts, (d) hazy vision, (e) blurred vision, (f) distortion, (g) multiple images, (h) visual fluctuations, (i) difficulty focusing, and (j) difficulty judging distance or depth perception. Respondents use a scale of 0 to 3, where zero (0) denotes "none," one (1) "a little," two (2) "quite a bit," and three (3) "very much." Furthermore, on a scale from 0 to 10, patients were asked to provide Likert ratings for "daytime" and "nighttime" quality of vision (0 denoting the poorest vision, while 10 indicating the best vision)	12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Refractive results	The uncorrected distance visual acuity (UDVA, logMAR), corrected distance visual acuity (CDVA, logMAR), subjective refraction (Diopter), and intraocular pressure (mmHg) were evaluated prior to and 1 year after SMILE.	12 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ocular high-order aberrations	Corneal aberration measurements were performed using a Scheimpflug tomography system (Pentacam; Oculus GmbH, Wetzlar, Germany). Images of the highest quality (designated as OK) were selected for analysis. The coefficients for a standardized diameter of 8 mm were examined, followed by an assessment of the clinical significance of total higher-order aberrations (HOA, mm), spherical aberration (Z4, 0, mm), horizontal coma (Z3, 1, mm), vertical coma (Z3, -1, mm), horizontal trefoil (Z3, 3, mm), and oblique trefoil (Z3, -3, mm)	12 months

Collaborators and Investigators

• Sponsor: yuhao shao
• Collaborators: Shanghai 10th People's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2021
• Primary Completion (Actual): September 1, 2024
• Study Completion (Actual): September 1, 2024

Study Registration Dates

• First Submitted: March 13, 2025
• First Submitted That Met QC Criteria: March 20, 2025
• First Posted (Actual): March 27, 2025

Study Record Updates

• Last Update Posted (Actual): March 27, 2025
• Last Update Submitted That Met QC Criteria: March 20, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: SMILE; High myopia; Axial length; visual quality; Higher-order aberration
• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Myopia
• Other Study ID Numbers: 2025AL; YJXYS-B-009 (Other Grant/Funding Number: Shanghai Tenth People's Hospital); 202240131 (Other Grant/Funding Number: Shanghai Municipal Health Commission)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No