To evaluate the clinical treatment effects of orthokeratology to slow the progression of myopia. Several well-designed controlled studies have investigated the effects of orthokeratology in school-aged children. We conducted this meta-analysis to better evaluate the existing evidence. Relevant studies were identified in the Medline and Embase database without language limitations. The main outcomes included axial length and vitreous chamber depth reported as the mean ± standard deviation. The results were pooled and assessed with a fixed-effects model analysis. Subgroup analyses were performed according to geographical location and study design. Of the seven eligible studies, all reported axial length changes after 2 years, while two studies reported vitreous chamber depth changes. The pooled estimates indicated that change in axial length in the ortho-k group was 0.27 mm (95% confidence interval [CI]: 0.22, 0.32) less than the control group. Myopic progression was reduced by approximately 45%. The combined results revealed that the difference in vitreous chamber depth between the two groups was 0.22 mm (95% confidence interval [CI]: 0.14, 0.31). None of the studies reported severe adverse events. The overall findings suggest that ortho-k can slow myopia progression in school-aged children.

The current study aimed to examine the short-term choroidal response to optical defocus in schoolchildren. Myopic schoolchildren aged 8–16 were randomly allocated to control group (CG), myopic defocus group (MDG) and hyperopic defocus group (HDG) (n = 17 per group). Children in MDG and HDG received additional +3D and -3D lenses, respectively, to their full corrections on the right eyes. Full correction was given to their left eyes, and on both eyes in the CG. Axial length (AXL) and subfoveal choroidal thickness (SFChT) were then measured by spectral domain optical coherence tomography. Children wore their group-specific correction for 2 hours after which any existing optical defocus was removed, and subjects wore full corrections for another 2 hours. Both the AXL and SFChT were recorded hourly for 4 hours. The mean refraction of all subjects was -3.41 ± 0.37D (± SEM). SFChT thinned when exposed to hyperopic defocus for 2 hours but less thinning was observed in response to myopic defocus compared to the control group (p < 0.05, two-way ANOVA). Removal of optical defocus significantly decreased SFChT in the MDG and significantly increased SFChT in the HDG after 1 and 2 hours (mean percentage change at 2-hour; control vs. hyperopic defocus vs. myopic defocus; -0.33 ± 0.59% vs. 3.04 ± 0.60% vs. -1.34 ± 0.74%, p < 0.01). Our results showed short-term exposure to myopic defocus induced relative choroidal thickening while hyperopic defocus led to choroidal thinning in children. This rapid and reversible choroidal response may be an important clinical parameter in gauging retinal response to optical defocus in human myopia.

PURPOSE: To compare the corneal biomechanical properties before and after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK in different levels of myopia with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, NY). METHODS: A total of 187 and 79 eyes that received SMILE or LASIK, respectively, between January and June 2013 at Zhongshan Ophthalmic Center were enrolled in this study. Patients were grouped according to surgery type (SMILE or LASIK) and −6.00 diopters (D) or less (⩽ −6.00 D) or myopia greater than −6.00 D (>−6.00 D). Corneal hysteresis, corneal resistance factor, and 37 waveform parameters were recorded and compared preoperatively and at 1 week and 1 and 3 months postoperatively. RESULTS: There was a significant decrease of corneal hysteresis, corneal resistance factor, p1area, and p2area, and an increase of path1 and path2 in both SMILE and LASIK. In myopia −6.00 D or less, the differences between SMILE and LASIK were not significant ( P > .05), but in myopia greater than −6.00 D, the corneal hysteresis, corneal resistance factor, p1area, and p2area decreased significantly more in LASIK than in SMILE ( P < .05). CONCLUSIONS: When comparing SMILE with LASIK, myopia was greater than −6.00 D, and the corneal hysteresis, corneal resistance factor, p1area, and p2area decrease was less after SMILE. [ J Refract Surg . 2014;30(10):702–707.]

The prevalence of myopia in young adults in East and Southeast Asia is approximately 80% to 90% owing to intensive education and limited time outdoors.¹ Because myopia is irreversible and requires eyeglasses, which are considered by some to be inconvenient, many adults undergo refractive surgery, including corneal refractive surgery and intraocular refractive surgery. Corneal refractive surgery is essentially laser vision correction with a femtosecond laser or excimer laser. However, iatrogenic ectasia due to biomechanical decompensation may occur if a patient with an at-risk cornea or a subclinical keratoconus (KC) has undergone ill-advised laser vision correction. This type of corneal ectasia is characterized by a thinning and forward protrusion of the center of the cornea, accompanied by irregular astigmatism, and can affect visual quality or even cause vision loss. Evaluating corneal morphologic characteristics with corneal topographic and tomographic testing before laser vision correction is necessary to exclude at-risk corneas.

Purpose: To evaluate decentration from pupil center and corneal vertex normal following femtosecond laser small incision lenticule extraction (SMILE) for the treatment of myopia and myopic astigmatism. Methods: This study evaluated 101 eyes of 101 patients with a spherical equivalent (SE) of −5.30 ± 1.72 diopters (D). Decentration was measured in the pupil-centered group (PC group) by video capture images and in the vertex normal–centered group (VNC group) using the WaveLight Oculyzer II (Alcon). The PC and VNC groups were further divided into 4 subgroups (1 PC, 2 PC and 1 VNC, 2 VNC) based on the displacement of the lenticule center. Uncorrected and corrected distance visual acuities, manifest refraction, and wavefront errors were measured preoperatively, and at 1 day, 1 week, 1 month, and 3 and 6 months postoperatively. Results: Regarding efficacy and safety, at 6 months postoperatively, 65, 71, 83, and 53% of eyes had unchanged corrected distance visual acuity in 1 PC, 1 VNC, 2 PC and 2 VNC groups, respectively. Also, 97, 98, 100, and 97% of treated eyes had a postoperative uncorrected distance visual acuity 20/20 or better in the subgroups, respectively. In the groups mentioned above, 96, 100, 100, and 95% of eyes, respectively, were within ±0.5 D of the targeted SE. In terms of total higher-order aberrations, the 1 PC group was significantly higher than the 1 VNC group (P = 0.04), whereas the 2 VNC group was significantly higher than the 2 PC group (P = 0.02). Conclusions: Our results demonstrate that better refractive outcomes will be achieved when the lenticule center is closer to the corneal vertex normal.

PURPOSE: To evaluate the clinical results of suction loss in eyes during small incision lenticule extraction (SMILE). METHODS: This prospective paired-eye case study enrolled 8,490 eyes of 4,296 patients, of which 35 eyes experienced suction loss during the SMILE procedure while being treated for myopia or myopic astigmatism. The eyes with suction loss were re-treated with SMILE, femtosecond laser-assisted LASIK (FS-LASIK), or pseudo SMILE, and the fellow eyes were treated with SMILE. Patients were examined before surgery and at 1 day, 1 week, and 1 and 3 months postoperatively. Corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), manifest refraction, higher order aberrations (HOAs), and morphologic modifications of corneal architecture were evaluated. At 3 months, patients were asked if they preferred the vision in either eye. RESULTS: High-contrast CDVA was worse in the eyes that suffered loss of suction than in the fellow eyes at 1 week postoperatively (two-tailed paired t tests, P = .04), but not at 1 and 3 months. There was no statistical significance between the two treatments in the safety and efficacy indices or the 3rd and 4th order aberrations at 3 months postoperatively (two-tailed paired t tests, all P > .05). No apparent abnormalities were observed in the corneas by frequency-domain optical coherence tomography. CONCLUSIONS: Re-treatment with femtosecond laser for incomplete SMILE was safe, predictable, and effective, and the patients did not perceive a difference in vision. [ J Refract Surg. 2016;32(10):686–692.]