Refractive outcomes and optical quality of PRESBYOND laser-blended vision for presbyopia correction.

AIM: To investigate the one-year refractive outcomes and optical quality following PRESBYOND laser-blended vision (LBV). METHODS: This retrospective study included 20 patients who underwent PRESBYOND treatment between Jan 2019 and Aug 2020. The patients were asked to attend a follow-up outpatient visit one year after surgery. Distance and near visual acuity as well as subjective refraction were examined. Optical quality was assessed using wavefront-supported custom ablation. A questionnaire evaluating optical quality and satisfaction was completed at the last visit. RESULTS: The average patient age was 48.1±7.4y (range, 41 to 58y). The mean preoperative spherical equivalent was -7.59±2.39 D. At the one-year follow-up, two eyes (both dominant eyes) lost one line of corrected distance visual acuity (CDVA), while the remaining eyes (38/40) maintained or gained lines of CDVA. The average binocular uncorrected distance visual acuity improved from 0.15±0.03 to 0.90±0.26 (decimal vision; P<0.001). The average binocular uncorrected near visual acuity increased from 0.34±0.28 to 0.97±0.07 (P<0.001). The spherical aberration was 0.04±0.06 µm in the nondominant eye and 0.09±0.09 µm in the dominant eye (P=0.02). All patients were satisfied with or accepted the outcomes of the surgery. The primary complaints were related to disturbances in night vision and relatively inferior near vision. CONCLUSION: Over the one-year observation period, PRESBYOND is a safe and effective option for presbyopia correction. The optical quality and near vision deserve further investigation.

One-step viscoelastic agent technique for ICL V4c implantation for myopia.

AIM: To investigate the safety and efficacy of using a one-step viscoelastic agent technique for posterior chamber phakic implantable collamer lens with a central hole (ICL V4c) implantation for myopia correction. METHODS: The one-step viscoelastic agent technique for ICL V4c implantation was used in 100 eyes of 52 patients. Refractive outcomes, intraocular pressure (IOP), corneal endothelial cell, and corneal densitometry values were evaluated at 1d, 1wk, 1 and 3mo postoperatively. RESULTS: All the surgeries were uneventful. No corrected distance visual acuity was lost after 3mo. IOP was 16.12±3.18 mm Hg before surgery, and 14.74±3.08 mm Hg at 1d and 14.50±2.56 mm Hg at 3mo after surgery (P<0.05). Corneal endothelial cell density was 2580±242 cell/mm2, the coefficient of variation in cell size was 42.11%±7.92%, and the percentage of hexagonal cells was 40.98%±9.46% before surgery. No significant difference was found when these outcomes were compared between the studied time points (P>0.05). The corneal densitometry values of the central 2 mm and 2 to 6 mm areas showed similar regularities. After surgery, the values significantly increased at 1d, then decreased to the preoperative values at 1wk, and then continued to decrease at 3mo (P<0.05). CONCLUSION: The one-step viscoelastic agent technique for ICL V4c implantation is found to be safe and effective for myopia correction and causes little disturbance to the cornea.

Objective optical quality and visual outcomes after the PresbyMAX monocular ablation profile.

AIM: To assess objective visual quality after presbyopia correction using the PresbyMAX monocular mode. METHODS: This prospective, nonrandomized study included 28 eyes from 18 patients (mean age 50.4±5.6y) who underwent presbyopia correction with the PresbyMAX monocular mode. Monocular and binocular visual acuities were evaluated preoperatively, 1d, 1wk, 1, 3mo, and 1y after surgery. Optical quality was analyzed by Hartmann-Shack wavefront aberration supported cornea ablation. Modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scattering index (OSI) were analyzed using an optical quality analysis system. RESULTS: One year after surgery, 100% and 94.4% of patients achieved binocular uncorrected distance and near visual acuity of 20/25, respectively. At the last visit Spherical aberration and total higher aberration were higher than the corresponding preoperative levels (P<0.001); however, no significant difference was found in MTF, OSI, or Strehl ratio. Transient decreases in OSI and MTF mainly occurred in the nondominant eyes. There was no significant difference in optical quality between the dominant and nondominant eyes, except for spherical aberration and horizontal coma (P<0.05). CONCLUSION: The PresbyMAX monocular mode is safe and effective for presbyopia correction. It has little effect on optical quality, though short-term degraded optical quality occurred mainly in the bi-aspheric ablated eyes.

Safety and satisfaction of myopic small-incision lenticule extraction combined with monovision.

BACKGROUND: To investigate the safety and optical quality of small-incision lenticule extraction (SMILE) combined with monovision, and patient satisfaction with the procedure. METHODS: The present study assessed a non-random case series involving 60 eyes of 30 patients (mean age 45.53 ± 3.20 years [range 41 to 52 years]) treated bilaterally using the VisuMax 500 system (Carl Zeiss Meditec, Jena, Germany) between January and July 2016. The target refraction was plano for the distance eye, and between - 0.5 and - 1.75 diopters (D) for the near eye. Visual acuity, refraction errors, ocular aberrations, and satisfaction questionnaire scores were calculated 1 year after surgery. RESULTS: All surgeries were uneventful, with a mean safety index of 1.03 and 1.04 in dominant and nondominant eyes, respectively. Binocular uncorrected distance visual acuity of all patients was ≥20/32, while binocular uncorrected near visual acuity was ≥20/40 1 year postoperatively. Higher-order aberration (0.45 ± 0.14, 0.51 ± 0.15 µm), spherical (0.18 ± 0.15, 0.21 ± 0.14 µm) and coma aberration (0.31 ± 0.16, 0.27 ± 0.17 µm) were identical between dominant and nondominant eyes after surgery. The overall satisfaction rate was 86.7% (26/30), with large contributions from age (OR = 1.76 95% CI: 1.03-2.53; P = 0.036). Binocular uncorrected distance visual acuity was related to preoperative spherical diopter (r = - 0.500; P = 0.005). CONCLUSIONS: Monovision appears to be a safe and effective option for myopia patients with presbyopia who are considering the SMILE procedure. Patients with younger age were more satisfied with the procedure.

Cap morphology after small-incision lenticule extraction and its effects on intraocular scattering.

AIM: To investigate cap morphology after small-incision lenticule extraction (SMILE) and its effects on intraocular scattering. METHODS: Sixty-five eyes of 33 patients undergoing SMILE were enrolled. In addition to regular evaluation, Fourier-domain optical coherence tomography was used to investigate cap thickness at 1d, 1wk, 1 and 3mo postoperatively. The optical quality including modulation transfer function cutoff frequency, Strehl ratio, Optical Quality Analysis System (OQAS) values, and objective scattering index (OSI), were evaluated using OQAS™. RESULTS: Cap thickness decreased from 1d to 1wk (P<0.001), but remained higher than intended thickness of 120 µm after 3mo (P<0.001). Cap thickness in central area was thinner than that of in the paracentral and peripheral areas (P<0.0001). Total number of microdistortions decreased from 1d to 3mo (P<0.0001). Pearson analysis revealed a weak correlation between OSI and standard deviation of cap thickness at 1d and 1mo, as well as between range of cap thickness and OSI at 1mo. No correlation was found between microdistortion and OSI, but a negative correlation existed between microdistortion and range at 1d and 1moafter surgery. CONCLUSION: The corneal cap tends to be more accurate and regular with time lapse. Better cap morphology tends to contribute less intraocular scattering in the eyes undergoing SMILE.

Refractive Regression and Changes in Central Corneal Thickness Three Years after Laser-Assisted Subepithelial Keratectomy for High Myopia in Eyes with Thin Corneas: A Retrospective Study.

This retrospective study aimed to explore refractive regression and central corneal thickness (CCT) following laser-assisted subepithelial keratectomy (LASEK) performed for the correction of high myopia in eyes with thin corneas. Forty patients (19 male, 21 female; mean age, 28.5 years) representing 76 treated eyes were included. The mean optical zone was 6.10 ± 0.32 mm, and the mean ablation depth was 121.53 ± 15.48 µm. CCT was significantly greater three years after surgery than at three months after surgery (425.66 ± 15.44 vs. 385.20 ± 12.81, respectively; p<0.001). The mean change in CCT from three months to three years was 40.46 ± 14.02 µm. The SE at three years was greater than that at three months (p<0.001). Although there was refractive regression, these data suggest that LASEK may have utility in the correction of high myopia in eyes with thin corneas.

Implantable collamer lens for residual refractive error after corneal refractive surgery.

AIM: To assess the safety, efficacy, predictability and stability of implantable collamer lens (ICL) for residual refractive error after corneal refractive surgery. METHODS: This study evaluated 19 eyes of 12 patients who underwent ICL implantation after corneal refractive surgeries. They were followed up for 1y to 5y of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractive error, flat and steep K value, axial length, intraocular pressure, corneal endothelial cell density, adverse events after ICL surgery. RESULTS: The mean follow-up period was 39.05±19.22 mo (range, 1-5y). Spherical equivalent refractive error changed from -7.45±3.02 D preoperatively to -0.85±1.10 D 1wk to 1mo after ICL implantation, with the safety and efficacy indices being 1.12 and 1.15, respectively. A total of 52.63% of eyes were within ±0.5 D of the predicted spherical equivalents, 73.68% were within ±1.0 D. A trend of mild regression towards myopia with axial elongation after 5y was observed. One eye with mild anterior capsule opacity and retinal detachment 1y after surgery were observed. CONCLUSION: ICL implantation is safe and effective for the correction of residual refractive error after corneal refractive surgeries, especially in moderate to high residual myopia.

Refractive change in the adult rabbit eye after corneal relaxation with the femtosecond laser.

BACKGROUND: A new procedure to correct myopia that does not disturb the cornea in the optical zone and avoids injuring the corneal epithelium could be a key advance in corneal refractive surgery. The aim of this study is to observe the refractive change in the adult rabbits undergoing femtosecond laser-assisted multilayer intrastromal ablation in the mid-periphery of the cornea without injury of epithelium. METHOD: The right eyes of 8 New Zealand White adult rabbits were used for the experiments. A 60-kHz femtosecond laser delivery system was used, and three lamellar layers of laser pulses were focused starting at a corneal depth of 180 µm and ending at 90 µm from the surface, with each successive layer placed 45 µm anterior to the previous layer. In the interface of the applanation contact lens cone, a 6-mm diameter aluminum circle was placed at the center to block the laser, limiting ablation to the mid-periphery of the cornea. The laser settings were as follows: spot/line separation, 10 µm; diameter, 8.0 mm; energy for ablating the stroma, 1.3 µJ. An authorefractor was used to assess the manifest refraction. RESULTS: Mean spherical equivalent (SE) (mean ± SD, SD: standard deviation) was significantly increased at postoperative week 1 (1.67 ± 0.26 D, p < 0.0001), month 1 (1.65 ± 0.23 D, p < 0.0001), and month 3 (1.60 ± 0.22 D, p < 0.0001) compared to baseline (0.68 ± 0.27 D). Mean spherical equivalent showed no significant change between postoperative week 1 and month 3 (p = 0.1168). CONCLUSION: Femtosecond laser-assisted multilayer corneal intrastromal ablation in the mid-periphery may cause a consequent hyperopic shift with no refractive regression.

Inhibition of corneal fibrosis by Smad7 in rats after photorefractive keratectomy.

BACKGROUND: Haze or corneal subepithelial fibrosis is one of the common complications after refractive surgery procedures, such as photorefractive keratectomy (PRK), laser epithelial keratomileusis, and epipolis laser in situ keratomileusis, which would result in refractive regression, decreased visual quality, and corneal opacification. Haze directly resulted from corneal fibrosis mediated by transforming growth factor ß (TGFß). Smad7, an inhibitory Smad, can inhibit TGFß signal transduction. Recently, the effects of Smad7 on the inhibition of fibrosis in several organs have been studied, while little is known about the effects on cornea after PRK. This study was aimed to determine the effects of lentiviral-mediated Smad7 gene expression on corneal fibrosis in rats after PRK. METHODS: Four different experimental groups were established using right eyes of Sprague-Dawley rats. Thirty-two eyes underwent de-epithelialization only and served as a sham operation group (group 1). Ninety-six eyes underwent PRK operation and were further divided into group 2 (the PRK group) without lentivector administration, group 3 (the Lv-blank group) with control lentiviral vector without Smad7 administration, and group 4 (the Lv-Smad7 group) with Smad7 expressing lentiviral vector Smad7 administration. At 1 day, 1 week, 1 month, and 3 months after PRK, the transfection efficiency was determined by measuring the fluorescence signal as well as Smad7 protein and mRNA levels. Corneas were further processed for immunoblotting to assess the phosphorylation of Smad2 as a downstream event of TGFß/Smad signaling. The expression of fibrotic markers, such as α-smooth muscle actin (α-SMA), Type III collagen (collagen III), and cell cycle-related marker Ki67, was measured by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Lentivirus-mediated exogenous Smad7 gene expression in rat corneal tissue resulted in reduced activation of TGFß/Smad signaling caused by downregulation of phosphorylation of Smad2. Smad7 also downregulated the expression of TGFß2. Markers of cell proliferation and fibrosis, including Ki67, α-SMA, and collagen III, were inhibited by Smad7 up to 3 months after PRK operation. CONCLUSION: Smad7 gene transfer inhibits fibrogenic responses of cornea in rats after PRK.

[Advances in biomechanical effects of laser corneal refractive surgery].

Corneal biomechanical properties will change after laser refractive surgery, which can be evaluated by several biomechanical parameters. The biomechanical stress will decrease remarkably after LASIK, but thin flap is helpful to maintain its stress. Excimer laser surface ablation has biomechanical advantages over LASIK procedure. The femtosecond laser technology can achieve smooth and regular incision and make the angle design. Flap adhesion is stronger when completed by a femtosecond laser. Laser refractive surgery will become safer and achieve more stable outcomes with the emphasis on biomechanical effects.

Expression of Smad7 inhibits fibrogenic responses of keratocytes to transforming growth factor ß2.

BACKGROUND: Transforming growth factor ß (TGFß) is one of the most important growth factors in the development of fibrosis and scarring on cornea. Smad7, an inhibitory Smad, can inhibit TGFß signal transduction. In recent years, effects of lentiviral-mediated Smad7 on inhibition of fibrosis on some organs have been studied, while little is known about the effects on cornea. This study aimed to determine the effects of lentiviral-mediated Smad7 gene expression on keratocyte proliferation and fibrosis induced by TGF ß2 in vitro. METHODS: Keratocytes were cultured from corneal tissue isolated from Sprague-Dawley (SD) rats and transfected with Smad7 expressing lentiviral vector (Lv-Smad7) or non-functioning control vector (Lv-blank). Following the exposure to TGFß2, keratocytes were processed for immunoblotting to assess the phosphorylation of Smad2 as down-stream event of TGFß/Smad signaling. Expression of fibrotic markers α-smooth muscle actin (α-SMA), type III collagen (collagen III) were measured by Western blotting and quantitative real time polymerase chain reaction (PCR). Overall cell proliferation was determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the expression of cell cycle-related marker Ki67 at both mRNA and protein levels. RESULTS: The Smad7 gene transfer suppressed TGFß/Smad signaling in keratocytes by down-regulating phosphorylation of Smad2. Markers of cell proliferation and fibrosis including Ki67, α-SMA, collagen III were inhibited by introduction of Smad 7 into TGFß exposed keratocytes. Consequently, the rate of cell proliferation was attenuated. CONCLUSION: Smad7 gene transfer inhibited fibrogenic responses of keratocytes to TGFß2.

[The effects of protein-free calf blood extract for recovery of corneal nerve after LASEK and LASIK].

OBJECTIVE: To evaluate the effects of protein-free calf blood extract for recovery of corneal nerve after LASEK and LSEIK. METHODS: A prospective, randomized, control and double-blind study was carried out from January through February 2009 at Department of Ophthalmology, Eye Ear Nose and Throat Hospital of Fudan University. Forty-nine eyes of 25 patients who underwent LASEK were randomly divided into two groups. One group with 16 patients (32 eyes) was treated by protein-free calf blood extract eye gel which was defined as drug treated group and the other group with 9 patients (17 eyes) was not treated by protein-free calf blood extract eye gel which was defined as no drug treated group. Forty-four eyes of 23 patients who underwent LASIK were also randomly divided into two groups. One group with 13 patients (24 eyes) was treated by protein-free calf blood extract eye gel which was defined as drug treated group and the other group with 10 patients (20 eyes) was not treated by protein-free calf blood extract eye gel which was defined as no drug treated group. Protein-free calf blood extract eye gel was delivered in both drug treated groups 3 times per day for three months after surgery. Laser scanning confocal microscopic examinations were performed on 48 eyes in vivo. Central corneal sensitivity and tear break-up time (BUT) were tested on 93 eyes preoperatively and 1, 3, 6 months, and 1 year after surgery. The obtained dates in the study were analyzed using independent samples t-test, paired t-test and Mann-Whitney Test. RESULTS: The morphology observed by confocal microscope of sub-basal nerve fibers was not different between drug treated group and no drug treated group until the last follow up after LASIK or LASEK (Z = 0.0000, P = 1.00) and (Z = 0.0000, P = 1.00). Nerve fibers with interconnections were observed in drug treated group at 3 months after LASEK. The morphology of sub-basal nerve fibers had not recovered completely until 1 year after surgery. The central corneal sensitivity was better in drug treated group than in no drug treated group at 1 month after LASEK [(4.95 ± 0.84) µm, (3.62 ± 1.38) µm; t = 4.23, P < 0.01] and at 1 and 3 months after LASIK [(3.29 ± 1.40)µm, (2.35 ± 1.51) µm; t = 2.10, P < 0.05], [(4.31 ± 1.61) µm, (3.18 ± 1.62) µm; t = 2.31, P < 0.05]. At 6 months postoperatively, the central corneal sensitivity of both drug treated group and no drug treated group which underwent LASEK was not significantly different from pre-operation [(5.81 ± 0.35) µm; t = -1.26, P > 0.05], [(5.79 ± 0.36) µm; t = -0.70, P > 0.05]. At 6 months postoperatively, the central corneal sensitivity of drug treated group which underwent LASIK was not significantly different from pre-operation [(5.25 ± 0.91) µm; t = -1.87, P > 0.05]. No significant difference was seen in BUT between drug treated group and no drug treated group after LASEK or LASIK until 1 year after surgery [(8.13 ± 2.18) µm, (8.76 ± 1.64) µm; t = -0.90, P > 0.05], [(7.71 ± 2.14) µm, (7.45 ± 2.37) µm; t = 0.30, P > 0.05]. CONCLUSION: Protein-free calf blood extract could significantly promote the recovery of corneal nerve in the early period after LASEK and LASIK.

Influence of internal optical astigmatism on the correction of myopic astigmatism by LASIK.

PURPOSE: To investigate the influence of the origin of astigmatism on the correction of myopic astigmatism by LASIK. METHODS: A retrospective study was conducted of the records of 192 patients (192 eyes) undergoing LASIK for correction of myopia and myopic astigmatism from January to September 2010. Ocular residual astigmatism (ORA) and lenticular astigmatism (LA) were determined by vector analysis using objective refraction and Pentacam (Oculus Optikgeräte GmbH) imaging of both corneal surfaces. Patients were divided into two groups according to ORA (high ORA group: ORA/preoperative refractive astigmatism >1; normal ORA group: ORA/preoperative refractive astigmatism ≤ 1) and LA (high LA group: LA/preoperative refractive astigmatism >1; normal LA group: LA/preoperative refractive astigmatism ≤ 1). Procedural efficacy was compared between those eyes with and without a significant amount of internal optical astigmatism using index of success. RESULTS: Mean preoperative vectors for the astigmatism of the anterior cornea, posterior cornea, and lens were -1.33 × 3.0°, -0.33 × 95.3°, and -0.27 × 103.3°, respectively. Mean indices of success in the high and low ORA groups were 1.75 and 0.59, respectively (t=7.81, P<.001). Mean indices of success in the high and low LA groups were 2.07 and 0.70, respectively (t=12.36, P<.001). The higher indices of success in the high ORA and high LA groups suggest a lower efficacy of LASIK in treating astigmatism primarily located intraocularly. CONCLUSIONS: Myopic LASIK is less effective in correcting astigmatism when astigmatism is mainly located at the internal optics. Topography and refractive value should be incorporated in the treatment of patients when a significant amount of internal optical astigmatism is detected preoperatively.

The role of eIF5A in epidermal growth factor-induced proliferation of corneal epithelial cell association with PI3-k/Akt activation.

PURPOSE: After excimer laser surgery, epidermal growth factor (EGF) plays an important role in injured corneal epithelial cell on myofibroblastic cell formation in corneal stroma. The purpose of the study is to investigate the precise mechanism of EGF on corneal wound healing, particularly on epithelial proliferation and migration. METHODS: In this study we applied small interference RNA (siRNA) to knock down the expression of eukaryotic translation initiation factor 5A (eIF5A) in corneal epithelial cells. The relative mRNA and protein expression of matrix metallopeptidase 9 (MMP9) and proliferating cell nuclear antigen (PCNA) was determined via real-time PCR and western blot analysis. The proliferative potential of EGF was evaluated via a proliferation assay using the measurement of (3)H-thymidine incorporation ((3)H-TdR). HCEpiC apoptosis was subjected to flow cytometric analysis. RESULTS: The results showed eIF5A expression was enhanced and there was a statistically significant increase in EGF treatment compared to the control group. Real-time PCR, western blot analysis, and the proliferation assay demonstrated significantly lower MMP9 and PCNA expression and proliferation cell counts in eIF5A siRNA-treated groups versus significantly higher levels in EGF plus eIF5A siRNA-treated groups. The data analysis showed that eIF5A, MMP9, and PCNA expression decreased as a result of the inhibitor LY294002. Apoptotic cells were increased in the EGF plus eIF5A siRNA, EGF plus LY294002, and EGF plus eIF5A siRNA plus LY294002 groups as compared with the EGF siRNA group. CONCLUSIONS: These results indicate that EGF-induced upregulation of eIF5A stimulates corneal epithelial cell proliferation in vitro. EGF stimulation of corneal epithelial proliferation was through the phosphatidylinositol 3-kinase (PI3-k)/protein kinase B (Akt) signaling pathway.

Effects of femtosecond laser-assisted multilayer intrastromal ablation in the midperipheral cornea.

We describe the femtosecond laser-assisted midperipheral multilayer intrastromal ablation technique, which combines the benefit of radial keratotomy, ie, not disturbing the optical zone, with currently available technology to correct myopia. The technique was performed in 2 patients, both of whom experienced a decrease in mean corneal power. In 1 patient, the manifest refraction improved, with a 1-line increase in uncorrected visual acuity 1 day postoperatively. The multilayer intrastromal ablation technique, which flattens the cornea and decreases corneal power, can be used to correct moderate myopia without injuring the corneal epithelium.

[Analysis of flap thickness by anterior segment optical coherence tomography in different flap preparation styles of excimer laser surgery].

OBJECTIVE: To assess and compare the accuracy and regularity and short-term change of corneal flap in different flap preparation styles. METHODS: Eighty eyes of 40 cases were treated with laser-assisted subepithelial keratectomy. One hundred and fifty-five eyes of 78 cases were treated with laser in situ keratomileusis with 90 microm microkeratome flap preparation and eighty-two eyes of 42 cases were treated with laser in situ keratomileusis with 100 microm femtosecond laser flap preparation. Anterior segment optical coherence tomography was used to assess the thickness of epithelial or stromal flaps created with M2 microkeratome or VisuMax femtosecond laser by the same investigator 1 hour, 1 day, 1 week, 1 month and 3 months postoperatively, respectively. The thickness of twenty-five measuring points across each flap in LASIK, which were 1.5 mm, 2.5 mm and 3.5 mm away from vertex of cornea on the horizontal, vertical, 45 degrees and 135 degrees meridian respectively and the vertex of cornea itself, was evaluated. The results were analyzed with t-test or ANOVA by SPSS software. RESULTS: The thickness of epithelial flaps was (57.91 + or - 6.76), (54.94 + or - 4.65), (54.96 + or - 2.70), (55.26 + or - 4.27) and (53.86 + or - 5.56) microm at 1 hour, 1 day, 1 week, 1 month and 3 months respectively, with statistical significant difference between 1 hour and the other time points (F = 20.25, P < 0.05). The average thickness of stromal flaps on the vertex of cornea in microkeratome group was (129.16 + or - 12.10) microm, while (112.69 + or - 5.12) microm in the femtosecond laser group, which means the accuracy of flap preparation with femtosecond laser is better than with microkeratome. The absolute difference between actual and average thickness was (13.16 + or - 4.78) and (5.26 + or - 1.21) microm in the microkeratome group and femtosecond laser group, which means the reproducibility of flap preparation with femtosecond laser is better than with microkeratome as well. Flap morphology showed the feature of thin central area and thick peripheral area in microkeratome flap and uniformity in femtosecond laser flap, which illustrated the better regularity of femtosecond laser flap preparation. CONCLUSIONS: Anterior segment optical coherence tomography is a safe, quick and reliable facility to examine and assess flap morphology. Our results showed the accuracy and regularity of femtosecond laser flap preparation outweighed microkeratome flap preparation.

[The expression of Ki-67, TGF-beta(2) and alpha-SMA after the femtosecond laser-assisted intrastromal scanning in rabbit cornea].

OBJECTIVE: To study how the cornea would express Ki-67, TGF-beta(2) and alpha-SMA and how the cornea would heal when it is scanned intrastromally. METHODS: Twenty New Zealand white rabbits were randomly numbered and used for the experiments. The 60 kHz Intralase femtosecond laser delivery system was used to scan 35 rabbit corneas (of these corneas, 5 right corneas were from 5 rabbits). The unoperated 5 left eyes were used as control. The laser settings were: spot/line separation, 10 microm; diameter, 8.5 mm; energy for scanning the stroma, 1.3 microJ; scanning depth, 135 microm, no edge cuts were performed. Slit lamp was used to observe the cornea at 0.5 h, 1 h, 2 h, and 3 months after surgery. On day 1, 3, 7, 30, 90 after surgery, 6 and 1 scanned corneas at each time point were taken for Western blot and immunocytochemical detection respectively to detect the expression of TNF-alpha, Ki-67, TGF-beta(2) and alpha-SMA. RESULTS: Microbubbles were found in corneal stroma after surgery. The number of microbubbles tended to decrease significantly with time. At 2 h, the cornea turned to be transparent again. During 3-month follow-up, the cornea was always transparent and no haze appeared. Western blot analysis and immunocytochemical detection demonstrated that the expression of Ki-67 began to increase at day 1(0.0670 + or - 0.0008) and reached the peak at day 3 after surgery (0.6923 + or - 0.005). While there were significant difference with the control group at day 90 after surgery (t = 24.12, 57.22, 43.26, 39.78, 18.35;P < 0.05), a gradual decrease in expression of ki-67 could be detected from day 3 to 90. There were no significant change in the expression of TGF-beta(2) (t = 0.933, 0.856, 0.934, 0.970, 1.132) and alpha-SMA (t = 1.126, 1.235, 0.993, 1.175, 1.211) at all time points after surgery (P > 0.05). CONCLUSIONS: After intrastromal scanning, the expression of Ki-67 increases and the keratocyte is activated and proliferated. However, due to no epithelium injured and TGF-beta(2) confined to the epithelium, the activated and proliferated keratocytes could not be transformed into myofibroblasts.

[The effects on corneal wound healing of LASIK with ultra-thin corneal flaps and LASEK in rabbits].

OBJECTIVE: To evaluate the corneal wound-healing response of LASIK with ultra-thin corneal flaps and LASEK in rabbits. METHODS: It was an experimental study. Thirty-two adult New Zealand rabbits were divided into 2 groups with 16 each. Two surgical procedures, LASIK with ultra-thin corneal flaps and LASEK were performed on the right eye of each group, with the left eye as control. A myopic ablation of 10 diopters was performed in each group. Corneal wound-healing and histopathological changes of the ablation zone were studied through slit lamp, light microscope and transmission electronic microscope. The expression levels of collagen I , collagen III, fibronectin (FN) and transforming growth factor beta-1 (TGF-beta1) were investigated by immunohistochemistry and RT-PCR assays. RESULTS: In the group of LASIK with ultra-thin corneal flaps, the corneas were clear without haze followed by slight wound healing and fast recovery. While in the group of LASEK, corneal wound healing was obviously delayed. There was haze in grade 1 (62.5%) and grade 2 (37.5%) in 1 month, with grade 0.5 (43.75%) and grade 1 (56.25%) in 3 months. 1 month and 3 months after surgery, proteins and mRNA of collagen III, FN and TGF-beta1 were expressed in the anterior corneal stromal layer in each group. But the expression was much higher in the group of LASEK (t = 18.47, 11.98, P < 0.05). The protein and mRNA expression of collagen I had no difference between the two groups (t = 0.72, 0.36, 0.47, 2.38, P > 0. 05). The mRNA expression of collagen I, collagen III, FN and TGF-beta1 had no statistical difference between the groups of control and LASIK with ultra-thin flap in 3 months (t = 2.42, 1.54, -0.83, P > 0.05). CONCLUSION: According to the animal experiments, it was suggested that the corneal wound-healing response of LASIK with ultra-thin corneal flaps was much better than that of LASEK.

[Clinical study of diffuse lamellar keratitis after laser in situ keratomileusis].

OBJECTIVE: To investigate a new clinical grading scale of diffuse lamellar keratitis (DLK) following laser in situ keratomileusis (LASIK) and to observe the clinic outcomes of eyes treated with corresponding classified therapy. METHODS: It was a prospective case-control study. Eyes that developed DLK after LASIK were diagnosed by a new criterion of clinical grading scale based on both severity and scope of inflammatory cells infiltrations in the corneal interface. Dose and frequency of topical or systemic corticosteroid were determined by the classified profiles according to each grade. Clinical symptoms, corneal inflammatory cells infiltrations, visual acuity, refractive error and intraocular pressure (IOP) were evaluated on 1, 3, 5, 7, 10 days and 1 month after diagnosis as well as at the time of diagnosis. RESULTS: Among the 35 eyes of 29 patients that developed DLK, mild inflammatory cells infiltrations were mostly seen. Thirty eyes had degree I DLK and 3 had degree II DLK. One eye had degree III DLK and one had degree IV DLK. Inflammatory cells infiltrations in 20 eyes invaded peripheral zone (zone 1) and those in 11 eyes invaded mid-peripheral zone (zone 2). Inflammatory cells infiltrates in 4 eyes invaded central zone (zone 3). Nineteen eyes had degree I zone 1 DLK. Thirty three eyes were diagnosed between the 1st day and the 3rd day after surgery. Uncorrected visual acuity (UCVA) was worse than preoperative best spectacle corrected visual acuity (BSCVA). Inflammatory cells infiltrations retreated within 6.06 2.04 days after classified corticosteroid therapy. One month after the treatment, UCVA had improved to the level of preoperative BSCVA. BSCVA in 30 eyes were equal to or better than those before surgery. Spherical equivalent of the refractive error was (-0.21 +/- 1.16) D. There was no statistic difference in the retreat time of inflammatory cells infiltrations, recovery of visual acuity and refractive error among the different grades of DLK or among the DLK treated with different therapy profiles. No eye suffered from high intraocular pressure during the treatments. CONCLUSIONS: Clinical grading scale and corresponding classified therapy were proved to be effective in the treatment for DLK.

Morphologic and histopathologic changes in the rabbit cornea produced by femtosecond laser-assisted multilayer intrastromal ablation.

PURPOSE: To observe morphologic and histopathologic changes in the midperiphery of the rabbit cornea produced by femtosecond laser-assisted multilayer intrastromal ablation, determine whether this method may be used to correct myopia, and study how the cornea heals when the epithelium is not injured. METHODS: The right eyes of 10 New Zealand White rabbits were used for the experiments. A 60-kHz femtosecond laser delivery system was used, and three lamellar layers of laser pulses were focused starting at a corneal depth of 180 microm and ending at 90 microm from the surface, with each successive layer placed 45 microm anterior to the previous layer. In the interface of the applanation contact lens cone, a 6-mm diameter aluminum circle was placed at the center to block the laser, and ablation was limited to the midperiphery of the cornea. The laser settings were spot/line separation, 10 microm; diameter, 8.5 mm; energy for ablating the stroma, 1.3 microJ. Topography examination was used to document changes in corneal power. Light microscopy, transmission electron microscopy (TEM), and confocal microscopy in vivo were applied to observe changes in the cornea. RESULTS: There was significant change in mean corneal power between baseline and postoperative month 3 (n = 8; P = 0.0001), with a decrease from 46.82 D to 44.42 D. There was no haze formation or refractive regression throughout the follow-up. There were no corneal structural abnormalities under light microscopy. Activated keratocytes and necrotic debris were visible under confocal microscopy. Fibroblasts were observed, and no myofibroblasts appeared under TEM. CONCLUSIONS: Multilayer intrastromal ablation by the femtosecond laser with intact epithelium in the midperiphery of the corneal stroma can flatten the cornea without causing haze formation or refractive regression. This procedure allows the cornea to heal differently than when traditional corneal refractive surgery is performed and the epithelium is damaged.