Comparison of Tear cytokines and clinical outcomes between off-flap and on-flap epi-LASIK with mitomycin C

Comparison of visual outcomes after femtosecond laser-assisted LASIK versus flap-off epipolis LASIK for myopia

Background

This study clinically evaluated the visual outcomes after refractive surgery for myopia using femtosecond laser-assisted in situ keratomileusis (femto-LASIK) and flap-off epipolis LASIK (epi-LASIK).

Methods

In this retrospective case series study, 40 eyes of 27 patients were divided into two groups depending on the technique used for refractive surgery. Femto-LASIK and flap-off epi-LASIK flaps were created using femtosecond laser and Epi-K™ epikeratome, respectively. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest refraction, corneal asphericity, and corneal higher-order aberrations (HOAs) were assessed pre- and postoperatively.

Results

The improvement in logarithm of the minimum angle of resolution (logMAR) UDVA after refractive surgery was statistically significant for both groups (P < 0.001 for all groups); it was significant better in UDVA in femto-LASIK than flap-off epi-LASIK, 0.03 ± 0.06 logMAR (femto-LASIK) and 0.54 ± 0.31 logMAR (flap-off epi-LASIK), at 1 day postoperatively; 0.02 ± 0.05 logMAR (femto-LASIK) and 0.14 ± 0.13 logMAR (flap-off epi-LASIK), at 1 week postoperatively (P < 0.001 and P = 0.019). With regard to the corneal HOAs, the increment in spherical aberration (Z_4,0) was greater in flap-off epi-LASIK than femto-LASIK: 0.626 ± 0.232 μm and 0.479 ± 0.139 μm in the front cornea; 0.556 ± 0.227 μm and 0.430 ± 0.137 μm in the total cornea (P = 0.016 and P = 0.017). However, the back corneal HOA changes did not have a significant effect on the total corneal HOA changes.

Conclusion

Femto-LASIK yielded better early visual outcomes than did flap-off epi-LASIK, but there was no significant difference between the outcomes of the two procedures, 1 week postoperatively.

[Association between hepatocyte growth factor in tears and corneal haze in rabbits early after epipolis laser in situ keratomileusis]

OBJECTIVE

To study the dynamic changes of levels of hepatocyte growth factor (HGF) in tears and their association with corneal haze in rabbits early after epipolis laser in situ keratomileusis (Epi-LASIK).

METHODS

Twenty-four New Zealand rabbits received Epi-LASIK with an ablation depth of 100 µm in one eye and of 150 µm in the other eye. Before and at 3, 7, 14, and 30 days after the surgery, the level of HGF in tears collected from the rabbits was measured using enzyme-linked immunosorbent assay (ELISA), and corneal haze was graded after surgery.

RESULTS

In all the rabbits, corneal epithelium healing occurred in 3 to 5 days after Epi-LASIK. Corneal haze appeared 3 days postoperatively in the rabbits accompanied by increased levels of HGF in tears. At 3, 7, 14, and 30 days after the surgery, the rabbits with an ablation depth of 150 µm showed more obvious corneal haze (P<0.05) and significantly higher levels of HGF in tears than those with an ablation depth of 100 µm (P<0.05).

CONCLUSION

In rabbits receiving Epi-LASIK, HGF levels in tears and the grade of corneal haze show a positive correlation early after the surgery and are both related with the depth of ablation.

Comparison of Early Changes in Ocular Surface and Inflammatory Mediators between Femtosecond Lenticule Extraction and Small-Incision Lenticule Extraction

Purpose

To evaluate the short-term changes in ocular surface measures and tear inflammatory mediators after femtosecond lenticule extraction (FLEx) and small-incision lenticule extraction (SMILE) procedures.

Methods

Eighteen subjects (18 eyes) underwent FLEx and 23 subjects (23 eyes) underwent SMILE in this single-center and prospective study. Central corneal sensitivity, Schirmer I test (SIT), noninvasive tear breakup time (NI-TBUT), tear meniscus height, corneal fluorescein (FL) staining, and ocular surface disease index (OSDI) were assessed in all patients. Concentrations of interleukin-1α (IL-1α), tumor necrosis factor-α (TNF-α), nerve growth factor (NGF), interferon-γ (IFN-γ), transforming growth factor-β1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) in collected tears were measured by multiplex antibody microarray.

Results

Central corneal sensitivity was reduced in both groups, but the scores in the SMILE group were higher than those in the FLEx group at all time points postoperatively (P<0.01). Lower FL scores and longer NI-BUT were observed in the SMILE group 1 week after surgery (P<0.05). OSDI scores in both groups increased rapidly at 1 day and 1 week postoperatively, then returned to their preoperative levels within 1 month (P<0.05). There were no significant differences in SIT or tear meniscus height between the two groups. Lower and faster recovery of tear NGF, TGF-β1 and IL-1α concentration were found in the SMILE group compared to the FLEx group postoperatively. No significant difference was found in tear TNF-α, IFN-γ and MMP-9 for either group before or after surgery. Tear NGF, TGF-β1 and IL-1α show a correlation with ocular surface changes after FLEx or SMILE surgery.

Conclusion

SMILE has superiority over FLEx in early ocular surface changes and NGF, TGF-β1 and IL-1α may contribute to the process of ocular surface recovery.

Trial Registration

ClinicalTrials.gov NCT02540785

Advances in Refractive Surgery

PURPOSE

The objective of this study was to review advances in the field of refractive surgery as reported in the peer-reviewed literature over the previous year.

DESIGN

This was a literature review.

METHODS

We conducted a PubMed search for terms related to refractive surgery and reviewed prominent international ophthalmic journals published from May 2012 through April 2013. All pertinent articles were reviewed, and selected articles with the greatest relevance were included.

RESULTS

Many studies over the previous year have highlighted progress in the field of refractive surgery; topics included keratoconus screening, photorefractive keratectomy and laser in situ keratomileusis, corneal cross-linking, small-incision lenticule extraction, phakic intraocular lenses, corneal inlays, presbyopic corneal treatments, and femtosecond laser-assisted astigmatic keratotomy.

CONCLUSIONS

The field of refractive surgery continues to provide exciting developments. Improvements in established procedures and promising new surgical options make the current climate an appealing one for refractive surgeons and patients.