Stromal Bed Research Articles

Deep anterior lamellar keratoplasty using the same graft after epikeratophakia for the treatment of acute corneal hydrops in keratoconus

Objective To evaluate the clinical effects of deep anterior lamellar keratoplasty (DALK) using the same graft after epikeratophakia for the treatment of acute corneal hydrops in keratoconus. Methods A consecutive 7 cases (7 eyes) with acute corneal hydrops in keratoconus in our department were retrospectively analyzed. Same corneal graft was used to perform the first stage epikeratophakia combined with C3F8 anterior chamber injection. About 6 months after the first surgery, the secondary stage deep anterior lamellar keratoplasty combined with air anterior chamber injection was performed. The best corrected visual acuity, healing status of the anterior and posterior corneal surface, anterior segment optical coherence tomography parameters, and corneal endothelial cells density were recorded. Results The central corneal thickness was (1764±256) μm before the treatment, and it was (778±147) μm, (604±23) μm, (579±20) μm and (525±19) μm at the time points of 1 d, 7 d, 1 and 6 months after the first stage surgery respectively. An average (6.1±1.3) months after the first stage surgery, the second stage DALK was performed. The descemet's membrane at the central area could be fully exposed in 3 eyes. Slow liquid exudations in the deep corneal stroma near the descemet's membrane were found in the other 4 eyes during stroma dissection. DALKs were successfully performed in all the 7 cases. Double anterior chambers were found in 2 eyes 1d after DALK. The whole corneal thicknesses were (781±57) μm, (581±49) μm and (521±19) μm at 7 d, 1 and 3 months after DALK respectively. Three months later, the thickness of the receptors' residual stroma bed was (21±11) μm at the central corneal area. At the end of the follow-up, the BCVA(LogMAR)was 0.11±0.03. Conclusion Novel curative effect was found in the treatment of acute corneal hydrops in keratoconus by deep anterior lamellar keratoplasty using the same graft after epikeratophakia. Key words: Acute corneal hydrops, keratoconus; Epikeratophakia; Keratoplasty, deep anterior lamellar; Anterior segment optical coherence tomography; Descemet's membrane

Moria One-Use Plus sub-Bowman’s keratomileusis head: a useful tool in the refractive surgeon’s armamentarium

Patients and methods A total of 500 eyes of 250 patients underwent laser in situ keratomileusis (LASIK) surgery using the One-Use Plus sub-Bowman’s keratomileusis head for the creation of an ultrathin LASIK flap. During the follow-up at 1, 6, 12, and 24 months, both uncorrected visual acuity (UCVA) and best-corrected visual acuity were recorded. A keratoconus screening corneal topography was carried out during the last follow-up visit. Results A total of 500 eyes of 250 myopic patients were included in this study. There were 115 male patients and 135 female patients. The mean age was 27.5 years (range: 18–44 years). The mean preoperative refractive error was −5.0 diopter sphere (DS) (range: −3 to −9 DS). The mean cylindrical error was −2.5 diopter cylinder (DC) (range: −0.75 to −4.5 DC). The mean UCVA was 0.07 (range: 0.01–0.3), and it improved to 1.0 (range: 0.8–1.25) on day 1 postoperatively. At the end of the follow-up, the mean UCVA was 1.0 and the mean best-corrected visual acuity was 1.0. The mean stromal residual bed thickness was 362 μm (range: 304–466 μm), and the mean central flap thickness was 102 μm (range: 82–120 μm). Complications were perilimbal bleeding in 15 eyes and fine irregular stromal edge cuts at the sides of the hinge in 10 eyes. There were no epithelial defects, no epithelial heaping or sliding, no irregular stromal bed surface cuts, no free caps or button holes, or incomplete flaps. Diffuse lamellar keratitis occurred in one eye of one patient, and no slipped flaps, macrostriae or microstriae, or epithelial downgrowth was seen during the follow-up period. At the end of the follow-up period none of our patients had topographic evidence of keratoconus. Conclusion The One-Use Plus sub-Bowman’s keratomileusis head is a safe and effective method for creating an ultrathin LASIK flap and allows the surgeon to treat higher errors of refraction while maintaining a higher safety margin by leaving more residual stromal tissue.

Self-assembly of vascularized tissue to support tumor explants in vitro.

Testing the efficacy of cancer drugs requires functional assays that recapitulate the cell populations, anatomy and biological responses of human tumors. Although current animal models and in vitro cell culture platforms are informative, they have significant shortcomings. Mouse models can reproduce tissue-level and systemic responses to tumor growth and treatments observed in humans, but xenografts from patients often do not grow, or require months to develop. On the other hand, current in vitro assays are useful for studying the molecular bases of tumorigenesis or drug activity, but often lack the appropriate in vivo cell heterogeneity and natural microenvironment. Therefore, there is a need for novel tools that allow rapid analysis of patient-derived tumors in a robust and representative microenvironment. We have developed methodology for maintaining harvested tumor tissue in vitro by placing them in a support bed with self-assembled stroma and vasculature. The harvested biopsy or tumor explant integrates with the stromal bed and vasculature, providing the correct extracellular matrix (collagen I, IV, fibronectin), associated stromal cells, and a lumenized vessel network. Our system provides a new tool that will allow ex vivo drug-screening and can be adapted for the guidance of patient-specific therapeutic strategies.

LASIK interface primary complications

Laser in situ Keratomileusis (LASIK) is one of the most accepted techniques in refractive surgery today. Its predictability, reproducibility, safety and low incidence of side effects justify the wide diffusion of this technique. This is a laser surgical procedure which purpose consists in the modification of corneal structure, allowing a shift of the focal point of the eye. Thus, it is possible to correct refractive errors such as myopia, astigmatism and small degrees of hyperopia. The LASIK technique creates a corneal flap interface with the use of a microkeratome or femtosecond laser. Then, excimer laser is applied on the stroma bed followed by repositioning of the flap, creating an interface between the anterior and posterior corneal lamella. Despite the numerous advantages there are patologies that originate from primary complications of the interface which can caused confusion during diagnosis because they have similarities in their clinical presentation. The aim of this work is to define, characterize and compare those entities with the intention of making the diagnosis easier so that there is appropriate conduct. As result, this study presents recommendations for the management of each kind of interface disease through investigation by medical history and physical examination, in order to allow differential diagnosis between the main primary entities of the LASIK procedure interface.

Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia.

Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p < 0.021). At 6 months, no eyes lost more than 1 line in corrected distance visual acuity. The safety index was 0.96 ± 0.06 and 1.00 ± 0.00 in SMILE Xtra and control, respectively (p < 0.001). 89% and 94% of eyes were within ±0.50 D of target refraction, respectively, with the mean error in SEQ correction being −0.17 ± 0.26 D for SMILE Xtra and +0.03 ± 0.25 D for control (p = 0.021). The efficacy index was 0.88 ± 0.13 and 0.97 ± 0.06, respectively (p = 0.005). Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

Single-Pass Microkeratome System for Eye Bank DSAEK Tissue Preparation: Is Stromal Bed Thickness Predictable and Reproducible?

To evaluate the predictability and reproducibility of stromal bed thickness for single-pass donor Descemet stripping automated endothelial keratoplasty (DSAEK) tissue preparation, using the ML7 Microkeratome Donor Cornea System (Med-logics Inc, Athens, TX). In this retrospective chart review of 256 consecutive corneal tissue preparations for DSAEK surgery, from June 2013 to August 2014, tissue thicknesses were divided into 3 groups, depending on surgeon preference: <91 μm (group A), 90 to 120 μm (group B), and 120 to 160 μm (group C). Precut and postcut data were recorded. Average postcut donor corneal thickness was 114 ± 30 μm (range 60-183 μm), whereas the average in group A was 97 ± 23 μm (range 60-128), in group B was 113 ± 21 μm (range 77-179), and in group C was 134 ± 43 (range 89-183). Average postcut endothelial cell density was very adequate at 3013 ± 250 cells per square millimeter. There were a total of 7 failed procedures from 256 attempts, which represents a rate of 2.7%. This rate decreases to 1.5% when analyzing the last 200 cuts. The ML7 Microkeratome Donor Cornea System allows for reliable and reproducible DSAEK tissue preparation. Ultrathin DSAEK tissues can be prepared with a single-pass. Aiming for a graft thickness between 90 and 120 μm seems to be most reliable.

Evaluation of combined corneal cross-linking with LASIK in risky patients

Objective The aim of this study was to evaluate the efficacy and safety of ultraviolet A irradiation cross-linking on completion of laser-assisted in-situ keratomileusis (LASIK) in risky patients to avoid post-LASIK ectasia. Background Patients with thinner-than-normal corneas, irregular corneal astigmatism, asymmetry on corneal topography, against-the-rule astigmatism, or steeper-than-normal corneas have higher risk of development of post-LASIK ectasia which need improvement in surgical interference. Materials and methods Forty-eight eyes of 30 myopic patients presented for LASIK at Al-Fardous Eye and Dental Hospital, Zagazig, Egypt, between September 2013 and August 2014. The study group comprised risky patients with corneal thickness of at least 480 μm and postoperative residual stromal thickness of at least 300 μm. After reflecting the flap, 0.1% riboflavin sodium phosphate solution was applied on the bare stromal bed and left to be soaked in for 60 s, and then the patient was positioned with the ultraviolet light (typically 365-370 μm). Results The study proved that there was an improvement in mean spherical error from −4.05 ± 1.19 preoperatively to −0.98 ± 0.12 on the second day postoperatively, and it improved to −0.59 ± 0.49, −0.49 ± 0.39, and −0.39 ± 0.36 at 1, 3, and 6 months postoperatively, respectively. These results showed a statistically highly significant difference (P 0.05) because we compared the results with the preoperative best-corrected visual acuity. Conclusion Application of riboflavin with ultraviolet after LASIK in risky patients improves refractive errors (spherical and cylindrical errors) and prevents post-LASIK corneal ectasia.

Efficacy and Safety of LASIK Combined with Accelerated Corneal Collagen Cross-Linking for Myopia: Six-Month Study.

This was a prospective controlled clinical trial. 48 myopia patients (96 eyes) were included in this study. After LASIK, accelerated corneal collagen cross-linking (ACXL) was used for myopia treatment. During 6-month follow-up, the results of LASIK-ACXL treatment were studied and compared to the LASIK-only procedure. The results showed that no statistically significant differences in UDVA, CDVA, MRSE, K mean, pachymetry, or ECD were found between the two groups at the visit after 6 months of follow-up (all P > 0.05). At 6 months postoperatively, 2 eyes lost one or more lines of visual acuity in the LASIK-ACXL group, whereas all LASIK-only treated eyes had a stable CDVA. In vivo confocal microscopy showed a decrease of keratocyte density and appearance of honeycomb-like structures in the anterior residual stroma bed; the changes were similar but more pronounced following LASIK-only. None of the cases in both groups developed signs of significant keratitis, regression, or ectasia during the 6-month follow-up. LASIK-ACXL can effectively correct refractive error in patients with myopia, with no significant complications during 6-month follow-up, indicating stability and morphologic change similar to those with LASIK-only treatment.

Safety and efficacy of VisuMax® circle patterns for flap creation and enhancement following small incision lenticule extraction.

BackgroundThe purpose of this case series is to evaluate the safety and efficacy of VisuMax® Circle patterns in eyes that have undergone small incision lenticule extraction, thus creating a flap to perform an enhancement procedure or residual lenticule extraction.MethodsThis prospective, single center, case study series evaluated the use of a VisuMax® Circle pattern to create a corneal flap following small incision lenticule extraction. Patients were treated and followed at TRSC International LASIK Center (Bangkok, Thailand) for 3 months to assess the efficacy and safety of the procedure. Efficacy was determined by the surgeon’s ability to lift the created corneal flap.ResultsThe study enrolled 28 eyes. Twenty-seven underwent the VisuMax® Circle pattern procedure for refractive enhancement, and one for residual lenticule extraction. In 100 % of cases (28 eyes) the lifting of the flap was possible, as planned. In all cases of refractive enhancement (27 eyes) by laser in situ keratomileusis (LASIK), the exposure of the stromal bed was sufficient for the necessary excimer laser ablation. No eyes lost two or more Snellen lines of corrected distance visual acuity (CDVA) and no procedure or flap-related complications or serious adverse events occurred.ConclusionsThis initial case series demonstrates that VisuMax® Circle pattern is efficacious and a suitable method to create a corneal flap for enhancement, following small incision lenticule extraction.

Options for a young patient with considerably high, topographically stable, astigmatism: December consultation #1

A 21-year-old woman was referred for a refractive surgery evaluation. She has no relevant allergies or medical or family history of keratoconus or corneal transplantation. Spectacle dependence is her chief complaint. She occasionally wears contact lenses but wants to have surgery performed. The corrected near visual acuity and the corrected distance visual acuity (CDVA) are 20/20 in both eyes. The manifest refraction is 5.75 3.25 178 in the right eye and 5.00 3.50 170 in the left eye. The intraocular pressure and the results from a slitlamp examination and a fundus retinoscopy are normal. The ultrasound pachymetry shows the central corneal thickness (CCT) to be 505 mm in the right eye and 508 mm in the left eye. Among all devices used tomeasure the CCT, the thinnest measured point is 504 mm in the right eye and 503 mm in the left eye. Placido-disk corneal topography shows a high regular symmetric astigmatism that was stable over 1 year of follow up, with an insignificant change in keratometry (K) values (Figure 1). The 5 topographies were obtained at 3-month intervals. Scheimpflug and dual Scheimpflug tomography (Figures 2, 3, and 4) are normal with no suspicious pattern except a high regular astigmatism. The pachymetry maps show corneas that, although slightly thin, are within normal limits across the diameter. An excimer laser system predicts a stromal ablation of approximately 127 mm in the right eye and 121 mm in the left eye. For laser in situ keratomileusis (LASIK) with a 110 mm flap thickness, the percentage of tissue altered (PTA) would be 47% in the right eye and 46% in the left eye. The residual stromal bed (RSB) would be 267 mm in the right eye and 272 mm in the left eye. For photorefractive keratectomy (PRK), the PTA would be 25% in the right eye and 24% in the left. What kind of refractive surgery (if any) would you recommend to this patient? If none, why? Would you consider LASIK with a thin, predictable LASIK flap? What data helped you most in making your decision? Did the stability shown by the Placido disk–based corneal topography over 1 year significantly affect your surgery decision?What are your limits for treating a cornea with high regular symmetric astigmatism? If you recommend proceeding with surgery, was age a significant factor in that decision?

Sécurité du microkératome automatisé pour le Kératomileusis sous-Bowman sur la cornée plate

Use of the One Use-Plus SBK (Sub-Bowman's Keratomileusis) automated microkeratome (Moria, Antony, France) has been shown to be safe, predictable and comfortable for the creation of thin corneal flaps with a smooth and regular stromal bed. To evaluate the use of the Moria One Use-Plus SBK (Moria, Antony, France) automated microkeratome on corneas with 180°-keratometry under 40 diopters (D). We retrospectively studied cases that underwent SBK whose 180°-keratometry was under 40 D. We separated the cases between 39 and 40 D and those less than 39 D. The preoperative data, the procedure and the postoperative outcomes were analyzed. The Moria One Use-Plus SBK microkeratome with the 90-micron head was used for all cases. Among the 2883 eyes that underwent SBK LASIK over the past six years, 80 eyes (2.77%) had a preoperative topographical 180°-keratometry of less than 40 D: 63 eyes (2.19%) between 39 and 40 D and 17 eyes (0.59%) between 38 and 39 D (38.13-38.97 D). The spherical equivalent was between -3.50 D (-2.25 sph -2.50 cyl. at 175°) and+6.00 D (+5.50 sph +1.00 cyl. at 85°). Fifty-eight eyes (72.5%) had hyperopia and/or hyperopic astigmatism; 18 eyes (22.5%) had mixed astigmatism; and 4 eyes (5%) had myopia and/or myopic astigmatism. Twenty-six eyes (32%) had a history of strabismus. Thirteen patients (27.66%) had a history of amblyopia. The "-1" ring was used in all cases, with a 7.5 stop (14%) or 8 stop (86%). The procedure went uneventfully in all cases with a stable vacuum between 117 and 123 mm Hg. The nasal hinge and the stromal bed were normal in size in all cases and sufficient to perform the photoablation laser safely with an optical zone between 6.00 and 7.00 millimeters. There were no intraoperative nor immediate postoperative complications: free cap 0%; incomplete flap 0%; button hole 0%; epithelial erosion 0%; bleeding 0%; irregular stromal bed 0%. Postoperative complications: flap displacement 0%; punctate keratitis: 8%; LASIK retreatments: 12%; safety: 100% (no loss of lines of visual acuity). Corneas with a topographical 180°-keratometry under 40 D are a very small percentage of the total eyes that undergo LASIK (SBK). Those with a 180°-keratometry under 39 D are even more infrequent. Due to the characteristics of the flat cornea, the percentage of hyperopia is much larger in than in the general LASIK group. In addition, the percentage with a history of strabismus and amblyopia is higher. The Moria One Use-Plus SBK microkeratome is an excellent device that allows the easy creation of thin corneal flaps and regular and smooth corneal beds, safely and predictably even in extremely flat corneas without complications. The safety, efficacy and predictability are quite comparable to the general LASIK group.

Laboratory Evaluation of Femtosecond Laser Lamellar Cuts in Gamma-Irradiated Corneas.

To evaluate the stromal interface quality after femtosecond laser full lamellar cuts in gamma-irradiated corneas (VisionGraft sterile cornea) and to determine the limits of the cut depth using the VisionGraft as donor corneas for laser-assisted lamellar anterior keratoplasty. Fourteen VisionGraft corneas underwent full lamellar cuts using the femtosecond laser. The percent cut depth was 17% to 21% (100 μm, n = 2), 31% to 35% (n = 3), 38% to 40% (n = 3), 45% to 48% (n = 3), and 50% (n = 3) of the total stromal thickness (not including the epithelium). The cap and stromal bed surfaces were imaged with a scanning electron microscope. The quality of cut surfaces was graded by 2 masked observers based on two indices: ridge and roughness. Ridge grading indicated macroscopic irregularity. Roughness grading indicated microscopic irregularity. The grading was done on a subjective integer scale of 1 to 5 (1 = best and 5 = worst), which was used in a previous study of cut quality in fresh corneas. The ridge grading ranged from 1.5 for the shallowest cut to 2.2 for the deepest cut and weakly (r = 0.279) but significantly (P = 0.037) correlated with the percent cut depth. The roughness grading ranged from 2.63 to 2.56 and showed no trend with the percent cut depth (r = 0.006, P = 0.968). Compared with previously published results of fresh corneas, in which ridge grading exceeded 3 for cuts deeper than 31%, cut quality was better for the VisionGraft. Even at depths up to 48% of the total stromal thickness, ridge grading was not worse than shallow cuts. Thus, gamma-irradiated corneas could provide a smoother interface than do fresh eye bank corneas for laser-assisted lamellar anterior keratoplasty.

Anterior Chamber Stabilization in Combined Penetrating Keratoplasty With Scleral-Sutured Posterior Chamber Intraocular Lens Implantation.

To describe a novel technique for a stabilized penetrating keratoplasty procedure with implantation of a scleral-sutured posterior chamber intraocular lens in which the anterior chamber (AC) is maintained and the globe stabilized without using a Flieringa ring. In this procedure, a deep anterior corneal lamella separation was created. Four small incisions were made in each quadrant along the outer edge of the trephination groove of the residual stromal bed (RSB). The first incision at the 9-o'clock position was advanced with scissors in both clockwise and counterclockwise directions. This procedure was repeated in the remaining 3 quadrants, creating 4 small bridges between the RSB and corneal rim. A donor corneal button coated with a viscoelastic material was sutured at 3 incision sites leaving 1 quadrant sutureless to allow sufficient incision width for IOL insertion for scleral fixation. Scleral fixation of a 1-piece polymethyl methacrylate (PMMA) IOL was performed. After sequential cutting of the bridges, the RSB was removed from the AC. Ten eyes of 10 patients underwent this procedure without significant complications. There were no complications related to the open-sky procedure. Globe stabilization was achieved in all surgeries. Endothelial cell loss, visual acuities, and graft failure rates were comparable with the reports of AC-protecting penetrating keratoplasty surgeries. This technique provides a secured AC and stabilized globe without the use of a Flieringa ring and increases the surgical safety without a significant reduction of the graft endothelial cell density.

Biomechanical Modeling of Femtosecond Laser Keyhole Endokeratophakia Surgery

To apply a finite element model to endokeratophakia and evaluate anterior and posterior corneal surface changes. Spatial elevation data (Pentacam HR; Oculus, Wetzlar, Germany) were obtained for the front and back corneal surfaces of an eye prior to undergoing an endokeratophakia procedure. These were used to warp a spherical template finite element model of the cornea to create a patient-specific finite element mesh and the initial stress distribution was computed with an iterative approach. The finite element model (Optimeyes; Integrated Scientific Services, Biel, Switzerland) included non-linear elastic characteristics of the stroma. The endokeratophakia procedure was recreated in the model: a donor lenticule (-10.50 diopters [D], 5.75-mm zone, 127-µm thick) was inserted into a lamellar pocket (180-µm deep, 6.25-mm diameter) and two 2-mm small incisions were made at 150° and 330°. Anterior and posterior surfaces, computed by the finite element model, were compared to clinical data to assess accuracy and reliability of finite element modeling. The postoperative axial curvature produced by the model closely resembled the patient data; average curvature was 48.01 D clinically and 48.23 D in the simulation, and corneal astigmatism was 3.01 D clinically and 2.88 D in the simulation. The posterior best-fit sphere elevation map also matched the patient data, replicating inward bulging of the posterior surface by approximately 40 µm. Stress distribution modeling predicted a stress increase by 159.94% ± 73% in the cap and a stress decrease by 32.41% ± 21% in the stromal bed. Finite element modeling of the cornea reproduced the clinically observed anterior and posterior corneal surface changes following an endokeratophakia procedure. This case sets the stage for further study to refine and yield predictive finite element modeling for the evaluation of corneal refractive surgical procedures.

Hydrogel Inlay for Presbyopia: Objective and Subjective Visual Outcomes

To evaluate changes in visual performance and ocular optical quality after implantation of a corneal hydrogel inlay as a treatment for presbyopia. A Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, CA) was implanted monocularly on the stromal bed of a femtosecond laser-assisted generated corneal flap of non-dominant eyes of 22 patients with emmetropic presbyopia (preoperative spherical equivalent range: -0.50 to 1.00 diopters). Efficacy was determined by measuring near and distance visual acuities and ocular aberrations, and satisfaction was assessed by a patient questionnaire. The preoperative monocular uncorrected near visual acuity of the inlay inserted eye was 20/129 ± 1 Snellen (range: 20/135 to 20/61 Snellen) and improved to 20/35 ± 2 Snellen (range: 20/61 to 20/20 Snellen) (P < .01) at 6 months postoperatively. The monocular uncorrected distance visual acuity of the eye receiving the inlay was 20/25 ± 2 Snellen (range: 20/50 to 20/20 Snellen) preoperatively and 20/25 ± 1 Snellen (range: 20/50 to 20/20 Snellen) at 6 months postoperatively (P =.257). According to the questionnaire responses, 82% of patients were satisfied. This was despite near glasses needs remaining in 13.6% of the cohort and the presence of glare and a decrease in night vision in approximately 40% of patients. The primary spherical aberration coefficient Z4(0) changed from positive to negative values in all patients (P < .01). However, the point spread function showed no significant change. Hydrogel corneal inlays improve uncorrected near visual acuity in patients with presbyopia with only moderate effect on visual quality. However, the satisfaction with this therapy was relatively lower in these Korean patients than that reported previously in Western patients.

Options for an eye with a thin cornea: June consultation #1

Journal of Cataract & Refractive Surgery: June 2015 - Volume 41 - Issue 6 - p 1324-1327 doi: 10.1016/j.jcrs.2015.06.006

Embryos engulf mom to latch on

Implantation![Figure][1] To implant, an embryo (black) must engulf uterine epithelial cells (arrows) PHOTO: Y. LI ET AL. CELL REPORTS 11 , 3 (21 APRIL 2015) © 2015 ELSEVIER INC. In mammals, to ensure a viable pregnancy, a developing embryo must implant into the wall of the uterus. Previous studies suggested that this depended on maternal uterine epithelial cells dying by apoptosis, a form of programmed cell death. However, Li et al. now report in mice that cells from the developing embryo actively engulf live cells of the uterine epithelial barrier, in a process called entosis. This then allows the developing embryo to anchor itself to the uterine stromal bed. Although scientists had previously reported a role for entosis in cancer, these results suggest that this process may be more widespread. Cell Rep. 11 , 358 (2015). [1]: pending:yes

Iatrogenic Keratectasia: A Review

Iatrogenic corneal ectasia is a rare complication but also one of the most feared situations that can occur after uneventful corneal laser surgery. Ectatic changes can occur as early as 1 week or can be delayed up to several years after LASIK. The actual incidence of ectasia is undetermined, an incidence rate of 0.04 to almost 2.8 % has been reported. Ectasia is most common following LASIK; however, cases have been reported following PRK and other corneal refractive procedures. Keratectasia shows progressive myopia, irregular astigmatism, ghosting, fluctuating vision and problems with scotopic vision. The progression leads to severe loss of corrected visual acuity. Risk factors are thin corneas < 500 µm, a pathological corneal topography, a residual stromal bed < 300 µm, high myopia > 8 D, young (female) age < 25 years, atopic dermatitis, allergies, family history for keratokonus and collagen diseases and retreatments. Treatment of choice is a cross-linking with riboflavin/UVA light with contact lenses. In severe cases a penetrating or a deep anterior lamellar graft is necessary.

Role of Percent Tissue Altered on Ectasia After LASIK in Eyes With Suspicious Topography

To investigate the association of the percent tissue altered (PTA) with the occurrence of ectasia after LASIK in eyes with suspicious preoperative corneal topography. This retrospective comparative case-control study compared associations of reported ectasia risk factors in 129 eyes, including 57 eyes with suspicious preoperative Placido-based corneal topography that developed ectasia after LASIK (suspect ectasia group), 32 eyes with suspicious topography that remained stable for at least 3 years after LASIK (suspect control group), and 30 eyes that developed ectasia with bilateral normal topography (normal topography ectasia group). Groups were subdivided based on topographic asymmetry into high- or low-suspect groups. The PTA, preoperative central corneal thickness (CCT), residual stromal bed (RSB), and age (years) were evaluated in univariate and multivariate analyses. Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons (P < .003) except high- and low-suspect ectasia groups (P = .033), and presented the highest discriminative capability of all variables evaluated. Age was only significantly different between the high-suspect ectasia and normal topography ectasia groups, and CCT was not significantly different between any groups. Stepwise logistic regression revealed the PTA as the most significant independent variable (P < .0001), with RSB the next most significant parameter. There remains a significant correlation between PTA values and ectasia risk after LASIK, even in eyes with suspicious corneal topography. Less tissue alteration, or a lower PTA value, was necessary to induce ectasia in eyes with more remarkable signs of topographic abnormality, and PTA provided better discriminative capabilities than RSB for all study populations.

Histopathological study of corneal flap striae following laser in situ keratomileusis in rabbits.

The aim of the present study was to investigate the histopathological changes and wound healing process of rabbit corneas following conventional laser in situ keratomileusis (LASIK) with and without the complication of flap macrostriae. The right eyes of 14 rabbits underwent LASIK with the formation of flap striae (macrostriae group) and the left underwent LASIK alone (control group). Two rabbits were selected at random for sacrifice on days 1, 3, 7 and 14, and at 1, 3 and 6 months postoperatively. The histopathological characters of the corneas were compared by hematoxylin and eosin (H&E), periodic acid-Schiff (PAS) and Masson staining. In the control group, the epithelial basement membrane of the cornea exhibited microstriae and the arrangement of stromal collagen fibers was regular. The width of the microstriae in the flap was 20–40 μm one week after surgery and the microstriae were no longer visible two weeks postoperatively. In the macrostriae group, infiltration of polymorphonuclear cells occurred around the incision and irregular hyperplasia of the epithelium was observed due to undulation of the epithelial basement membrane on the first postoperative day. The collagen fibers and striae of the corneal stroma exhibited irregular undulation one month postoperatively. The area between the corneal flap and stromal bed was distinctly stained by PAS and Masson stains. Macrostriae with a width of 80–120 μm affecting two-thirds of the entire cornea remained visible six months postoperatively. In conclusion, the inflammatory reactions and clinical impact of flap macrostriae were severe. Macrostriae involving two-thirds of the entire cornea remained visible six months postoperatively. Longer-term studies are required to further elucidate the issues associated with corneal flap striae.