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Effects of LASIK on Corneal Endothelium Using the 15-KHz IntraLase Femtosecond Laser

Effects of LASIK on Corneal Endothelium Using the 15-KHz IntraLase Femtosecond Laser

This prospective, interventional study evalu- ated consecutive patients who underwent bilateral simultaneous femtosecond LASIK for myopia rang- ing from 0.75 to 9.00 diopters (D) and cylinder up to 3.25 diopters (D). All patients had a stable refrac- tive history for 2 years. Written informed consent was obtained from all patients before surgery in accor- dance with the Declaration of Helsinki. Institutional review board approval was not required. Exclusion criteria were previous ocular surgery, mesopic pupil diameter 7.0 mm, central corneal endothelial cell density 2250 cells/mm 2 , corneal dystrophy, cataract,
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Immune cells on the corneal endothelium of an allogeneic corneal transplantation rabbit model

Immune cells on the corneal endothelium of an allogeneic corneal transplantation rabbit model

The recipient endothelium rarely showed the presence of these immune cells, suggesting that the allogeneic corneal endothelium has the ability to recruit immune cells. Consistent with the findings observed previously for the PK corneal grafts, TNF-a– and IFN-c–producing immune cells were also detected in the DSEK graft endothelium (Fig. 5E). Image stacks of specific depths and high resolution obtained by confocal laser scanning electron microscopy of the DSEK corneas revealed that these immune cells were attached onto the graft endothelium layer positioned at the anterior chamber site (Fig. 5F). The expression of cytokines related to inflammation was evaluated 2 weeks after DSEK in corneal endothelium that included immune cells. Semiquantitative RT-PCR showed higher expression of IL-1 receptor antagonist (IL-1RA), IL-1b, IL-6, IL-15, TNF-a, TGF-b2, CX3CR, and CCL2 in DSEK corneal endothelium than in healthy corneal endothelium, while IL-8, IL-10, TLR4, and TRAIL were detected at similar levels in both groups (Fig. 5G).
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Changes in corneal endothelium cell characteristics after cataract surgery with and without use of viscoelastic substances during intraocular lens implantation

Changes in corneal endothelium cell characteristics after cataract surgery with and without use of viscoelastic substances during intraocular lens implantation

All surgeries were performed by one single surgeon (SB) in an outpatient setting. Phacoemulsification was conducted if a clinically observed senile opacification of the lens was seen at slit lamp examination, and removal of the lens was expected to increase visual acuity as tested with laser interfer- ometer prior to surgery. The cataract surgery was performed as follows: temporal clear cornea incision of 2.6 × 2.5 mm, two side-ports, injection of OVD into the AC, anterior capsulorhexis under OVD Z-Celcoat, hydrodissection, pha- coemulsification with the Pentasys 2 ® device (Fritz Ruck
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Effects of the pulsed radio frequency used in magnetic resonance imaging on the corneal endothelium of humans

Effects of the pulsed radio frequency used in magnetic resonance imaging on the corneal endothelium of humans

transverse magnetization rapidly decays, while the longitudinal magnetization is growing at a slower rate. The magnetic field strength at each proton is not identical due to inhomogeneities in B0 and B j, different magnetic environments (chemical shifts), and spin-spin exchange processes. These magnetic inhomogeneities cause the protons to precess at different rates, so that after an appropriate amount of time the nuclear spins are spread out, or dephased, over the entire xy plane. This process of dephasing is often called spin-spin or transverse relaxation because it is caused by the interaction of spinning particles.
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Oxidative stress and premature senescence in corneal endothelium following penetrating keratoplasty in an animal model

Oxidative stress and premature senescence in corneal endothelium following penetrating keratoplasty in an animal model

DNA breaks and oxidative lesions caused by environ- mental insults, genetic defects, or endogenous processes belong to certain types of DNA damage. One of the crit- ical effects of oxidative stress caused by reactive oxygen species is the induction of cellular senescence [7, 8]. Numerous studies have reported that premature senes- cence is closely related to organ transplant [9–12], such as renal transplantation [13]. Cellular senescence is a state of irreversible growth arrest. It can be triggered by many kinds of oncogenic or stressful stimuli including telomere shortening, the epigenetic derepression of the INK4a/ARF locus [8, 14]. Studies with clinical outcome of HCECs showed the exhibition signs of oxidative DNA damage and that oxidative stress affects the proliferative capacity of HCECs [15, 16]. These authors also observed that, with respect to the senescence of corneal endothe- lial cells, age-related relative proliferative capacity and senescence characteristics are not due to replicative sen- escence caused by critically short telomeres in vitro [17].
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Changes in central corneal thickness and refractive error after thin-flap laser in situ keratomileusis in Chinese eyes

Changes in central corneal thickness and refractive error after thin-flap laser in situ keratomileusis in Chinese eyes

In this study, we used non-contact specular micros- copy to follow-up the CCT changes within 6 months post thin-flap LASIK treatment. We found that CCT values declined significantly at 1 day postsurgery, and continued to decline at 1 week. CCT values began to increase over time. Several processes occurred during the early postoperative period, including resorption of fluid introduced by intraoperative irrigation, biomech- anical hydration shift, epithelial thickness modulation in response to laser ablation, and interface reflectivity changes. However, in many reported cases, the sys- tematic changes are small after 1 week [7], and the posterior stroma is significantly thickened after 1 week postsurgery [8, 9]. Peng et al. [10] reported that just after LASIK surgery, keratocytes were activated by cy- tokines that induced collagen fiber synthesis. Kerato- cyte activation was strongest at 1 to 2 weeks, and persisted until 3 months after LASIK surgery [8, 9]. This could cause the increase in posterior stromal thickness, and may be why the CCT values continued to increase after 1 week postsurgery.
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CORNEAL ENDOTHELIUM OUTCOME AFTER TORSIONAL PHACOEMULSIFICATION SURGERY

CORNEAL ENDOTHELIUM OUTCOME AFTER TORSIONAL PHACOEMULSIFICATION SURGERY

Purpose: Corneal Endothelium Outcome After Torsional Phacoemulsification surgery. Desigen: prospective randomized study. Methods: This is a prospective study that was performed on 20 patients to estimate postoperative corneal endothelial outcome after cataract surgery performed with torsional phacoemulsification in senile cataracts. The current study has been conducted at Al-Azhar University Hospital Asyuit. Results: This is a prospective study that was performed on 20 patients to estimate postoperative corneal endothelial outcome after cataract surgery performed with torsional phacoemulsification in senile cataracts. Preoperative data including age, sex and grading of nucleus are Presented in Table (3). The Age group ranges from 55-65 years, including 12 males & 8 Females, all have Nuclear cataract grade II-III. In our trial we also conducted a more detailed study about the corneal endothelial cells as regard, Endothelial cell Count (Endothelial density) (CD), Average cell size (AVE), Maximum cell size (MAX), Minimum cell size (MIN), Coefficient of variation in cell size (CV), Standard deviation in cell density (SD), Pachymetry (PACHY), Best corrected visual acuity (BCVA), as well as the Percentage of the hexagonal cells (6A). Conclusion: Our results indicate that the torsional phacoemulsification is a safe method of removing uncomplicated senile cataract with less endothelial cell loss. Torsional phacoemulsification has the advantage of reducing UST as well as effective energy used. Phaco duration was the most significant intraoperative factor affecting the corneal endothelium. So Specular microscopy is a useful tool in preoperative assessment of cataract patients especially in cases undergoing phacoemulsification. This study is limited by a small sample size in hard cataracts. Nevertheless, the findings have meaningful clinical relevance to support the efficiency and safety of torsional phacoemulsification in medium density cataracts.
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The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome

The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome

On examining our CRF data, there was a greater reduction of CRF in both LASIK groups compared to the ASA group, although it did not attain statistical significance. However, the mean reduction in CRF was slightly higher in the thick-flap group compared to the thin-flap group (2.93 vs 2.77 mmHg, respectively). Since the mean ablation depth in the thin-flap group was greater than the thick-flap group (72 vs 59 µ m, respectively), we calculated the mean change in CRF per micron of ablation depth, and this was found to be higher in the thick-flap LASIK group (0.051 vs 0.040 mmHg/ µ m) than in the thin-flap LASIK group (p = 0.0805). While the difference missed statistical significance, it is worth noting that we used the two-tailed p-value throughout the study, as we were testing the null hypothesis in both directions. Should we have used the one-tailed p-value hypothesizing from the start that the reduction in the thin-flap LASIK group is greater than the thick-flap LASIK group, the difference would have been statistically significant (p = 0.045). Thus, after adjusting for differences in ablation depth, the mean reduction in CRF was also greater in the thick-flap group compared to the thin-flap group. It is also notable that the mean change in CRF per micron of ablation depth was very similar in the ASA and thin-flap groups (respectively, 0.039 and 0.040 mmHg/ µ m) (p = 0.891).
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Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results

Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results

Our previous analyses 6,16,17 showed that clinical out- comes after CXL are time dependent. Similarly, corneal topography appears to change over time during the first year after surgery. In general, the topography indices were worse at 1 month than at baseline. This worsening was similar to the initial worsening in postoperative vi- sual acuity 6 and CXL-associated corneal haze 16 in the early period after CXL. After the first month, there was progressive improvement in the index of surface variance, index of vertical asymmetry, minimum radius of curvature, and keratoconus index between 1 month and 6 months. Although the pathophysiology–wound healing etiology of this natural history after CXL is unclear, the early clinical worsening coincides with the reepithelialization process and with postoperative kera- tocyte apoptosis and repopulation, as noted in studies using confocal microscopy. 19 Therefore, this ongoing wound-healing process likely militates months-long changes in the topography of the cornea after CXL.
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Fluoroquinolone antibacterial eye drops: effects on normal human corneal epithelium, stroma, and endothelium

Fluoroquinolone antibacterial eye drops: effects on normal human corneal epithelium, stroma, and endothelium

The exclusion criteria for this study included a history of hypersensitivity to fluoroquinolones, corneal epithelial defects (including superficial punctate keratopathy (SPK)), conjunctivitis, a history of herpetic keratitis, abnormal lacrimation (a Schirmer I test measurement of 5 mm or less or a BUT measurement of 5 seconds or less), use of any antibacterial eye drops within 1 week of study entry, use of eye drops other than the study eye drops, use of contact lenses within 2 weeks of study entry, intraocular pressure of 21 mmHg or more, inability of the subject to provide written informed consent, and any other reason judged ineligible for participation in the study by the investigator.
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Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus

Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus

p= 0.005). This change might be explained by pointing out that the cause of spherical aberration is influenced by the alteration in the corneal curvature. Subsequent measurements resulted in a significant negative direction after 6 months, which may be due to the temporal evolution of surface ablation. At 12 months, there was another significant positive change in asphericity in the 6 mm ring diameter, while there were no changes verified at 7 mm and 8 mm. This finding is similar to the finding of Koller et al where they reported that Q ant was calculated within a circular area of 8 mm. As compared to the treated group, the untreated group showed an insignificant negative shift at the 1 year follow-up. This finding contrasted to that of Kovács et al where they reported on those who had relevant negative posterior Q-values because of corneal protrusion. However, they used a different way of measuring asphericity by measuring Q-value at the sagittal angle ring at 30 ° centered on the apex, which showed high accuracy (90% of specificity) and moderate sensitivity (60%). 25 This differ-
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Dispersive viscosurgical devices demonstrate greater efficacy in protecting corneal endothelium in vitro

Dispersive viscosurgical devices demonstrate greater efficacy in protecting corneal endothelium in vitro

Our results might lead to the conclusion that disper- sive OVDs are generally better than cohesive ones in protecting the corneal endothelium. However, besides endothelial coating, other important parameters influ- ence corneal health after cataract surgery such as the surgeon’s skill and experience in removing the OVD completely towards the end of surgery and the effect that the extent of this removal might have on the duration of the surgery. Prolonged I/A and the general length of time of surgery can influence the success of the surgery.

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The factors affecting specular microscopic changes in corneal endothelium in relation to cataract surgery

The factors affecting specular microscopic changes in corneal endothelium in relation to cataract surgery

Cheng et al (1977) in a study of operated patients ranging from age group 55-84, reported that mean endothelial cell loss in eyes with intraocular implants was more (41.3%) as compared to intracapsular cataract extraction (21.4%) (23). Diaz-Valle et al (1998) evaluated postoperative endothelial cell damage in various type of cataract surgery: group1-phacoemulsification, group2-planned ECCE with continuous curvilinear capsulorrhexis and group3-ECCE with letter-box capsulotomy. Endothelial response was not statistically significantly different among the surgical techniques, although endothelial damage was lower in group 3 (26). Sugar et al, (1977) confirmed the finding that intraocular lens implantation causes significantly greater endothelial damage than cataract extraction alone. Katz et al suggested that the direct trauma is the most significant factor to the endothelium at the time of surgery, showing that contact between the surface of an IOL and corneal endothelium instantaneously damages cells (81). Cheng et al. (1977) in study of operated patients ranging from age group 55-84, reported that mean endothelial cell loss in eyes with intraocular implants was more (41.3%) as compared to intracapsular cataract extraction (21.4%) (23). Diaz-Valle et al (1998) evaluated postoperative endothelial cell damage in various types of cataract surgery: group1-phacoemulsification, group2-planned ECCE with continuous curvilinear capsulorrhexis and group3-ECCE with letter-box capsulotomy.
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Fully convolutional architecture vs sliding-window CNN for corneal endothelium cell segmentation

Fully convolutional architecture vs sliding-window CNN for corneal endothelium cell segmentation

Background: Corneal endothelium (CE) images provide valuable clinical information regarding the health state of the cornea. Computation of the clinical morphometric parameters requires the segmentation of endothelial cell images. Current techniques to image the endothelium in vivo deliver low quality images, which makes automatic segmentation a complicated task. Here, we present two convolutional neural networks (CNN) to segment CE images: a global fully convolutional approach based on U-net, and a local sliding-window network (SW-net). We propose to use probabilistic labels instead of binary, we evaluate a preprocessing method to enhance the contrast of images, and we introduce a postprocessing method based on Fourier analysis and watershed to convert the CNN output images into the final cell segmentation. Both methods are applied to 50 images acquired with an SP-1P Topcon specular microscope. Estimates are compared against a manual delineation made by a trained observer.
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Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results

Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results

studies, as well as our previous analysis, found that ectatic corneas appear to have a less robust response to CXL than keratoconic corneas. 7,15 Similarly, in the current study, there was a significant difference in the change in all pachymetry measurements between keratoconus patients and ectasia patients 1 year after CXL. In ectasia patients, all three 1-year pachymetry measurements were slightly above preoperative mea- surements, whereas in the keratoconus patients the same pachymetry measurements were slightly below preoperative measurements. This difference was most evident in thinnest pachymetry. One-year post- operative measurements were significantly decreased from baseline in keratoconus patients but were not sig- nificantly different from baseline in ectasia patients. There appears to be similar thinning of ectatic corneas and keratoconic corneas between baseline and 3 months; however, ectatic corneas appear to recover (ie, rethicken) faster than keratoconic corneas. In sup- port of our early findings, therefore, it is possible that CXL does not have as robust or long-lasting bio- mechanical effect in the ectasia cornea as in the kerato- conus cornea, a difference that could also affect clinical outcomes. However, this remains speculative and any differences in CXL outcomes between keratoconus eyes and ectasia eyes must be further defined and elucidated.
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Flaporhexis: Alternative Way to Make a Femtosecond  Laser Corneal Flap

Flaporhexis: Alternative Way to Make a Femtosecond Laser Corneal Flap

the flap, or moved in a “windshield-wiper” motion across the cornea [4]. Surgeons who have started on 5, 10, or 15 Hz-femtosecond technology have chosen this technique because of its easy adaptability under the circumstances of rather imperfect photo disruption at the beginning of the aera of femtosecond laser corneal surgery. One dis- advantage, however, is that the steel instrument intrudes into a preformed corneal space, and there is a potential for via falsa penetration (Figure 12) of the tissue with the steel instrument in the case of imperfect photo dis- ruption of the corneal layers. Due to the varying initial interactions between the corneal tissue and the CO bub- bles formed by the femtosecond laser, effects of vertical or horizontal breakthrough may occur. The forming of an opaque bubble layer of softened and weakened tissue enables the perforation by the rectangular design of the Seibel-IntraLASIK Flap Lifter. To avoid this, the Femto- flapLIFTER has been given a curved physiologically better design (Figure 1). In some cases, the surgeon may not be able to exit the side cut at the opposite side of the hinge. To solve this problem the surgeon has to find variations from the intended plan. He can now widen the gap between corneal stroma and flap from hinge to pe- riphery by moving the instrument in a “multilane” fash- ion several times across the cornea to widen the dissec- tion space. Generally, in the hinge opening technique, the cooperation of the patient is needed [4] to counteract the said manipulations of the instruments by activation of the patient’s eye muscles (Figure 12). Some patients ex- perience frightening sensations here because they expect a gentle “bladeless” LASIK. In a complicated case, the intrusion of the instrument may also increase the chance of tissue damage and potential implantation of epithelial cells or detritus into the interface due to prolonged ma- nipulation. Thus, in otherwise uneventful treatments, microstriae are sometimes visible in the first postopera- tive week due to the mechanical stress on the flap’s inner
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Analysis of corneal endothelial cell density and morphology after laser in situ keratomileusis using two types of femtosecond lasers

Analysis of corneal endothelial cell density and morphology after laser in situ keratomileusis using two types of femtosecond lasers

IntraLase FS60 was used. The repetition rate of the pulse was 1 MHz for Femto LDV and 60 kHz for IntraLase FS60. Given that the spot size (.1 µ m) and energy of IntraLase FS60 is larger than that of Femto LDV (spot size: ,1 µ m), and given that the cutting process is driven by mechanical forces disrupting the surrounding tissues, the spot and line separation of IntraLase FS60 is larger than that of Femto LDV. Since smaller spot energy was used by Femto LDV, the disruption occurred locally, resulting in more pulses being required for disruption. After flap creation, excimer laser ablation for refractive correction was performed using ALLEGRETTO WAVE Eye-Q ® 400 Hz (WaveLight; Alcon
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Corneal topographic characteristics of persons seeking laser refractive surgery

Corneal topographic characteristics of persons seeking laser refractive surgery

Another alluring feature which made the Orbscan much more popular is the pachymetry map of the whole corneal surface. The data is generally displayed in a colour coded map. The normal ranges of corneal thickness are represented in green and the thinner areas of the cornea are represented in warm colours. Alarmingly thin areas are displayed in red. To provide a quick view, the bottom right map display depicts numerical values in 5 points which include the center of the cornea, and the superior, inferior, nasal and temporal points 3 mm from the center. The thinnest point of the cornea and its site of location with relation to the center is shown in the central box of the map.
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Predictability of corneal flap thickness in laser in situ keratomileusis using a 200 khz femtosecond laser

Predictability of corneal flap thickness in laser in situ keratomileusis using a 200 khz femtosecond laser

environment. With this femtosecond device, the centra- tion of the flap can be repositioned within a 10.0 mm di- ameter area, even after the suction ring has been applied. Via a computer network, the ablation profile is fed to the femtosecond laser, where it can be superim- posed on the cornea to adjust the flap profile to fit the ablation. By shifting the placement grid, the surgeon can customize flap placement to best fit the planned ab- lation. The femtosecond laser releases infrared laser pulses in a raster pattern onto the cornea, resulting in the formation of small cavitation bubbles within the tis- sue. The creation of thousands of cavitation bubbles in a lamellar pattern leads to the creation of a cleavage plane within the cornea. Subsequently, laser pulses are fired in a peripheral circular pattern onto the corneal stroma to create a vertical side cut and a hinge. This la- ser can make large-diameter corneal applanation zones, up to 13.0 mm, allowing comfortable margins when performing hyperopic LASIK. It automatically cuts a square tunnel through the flap's hinge that allows the cavitation gas to escape to minimize the develop- ment of an OBL. In addition, the beam target, size, and spacing are optimized to minimize the OBL, allow- ing the surgeon to perform an excimer laser treatment immediately after flap creation.
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Development of late-onset subepithelial corneal haze after laser-assisted subepithelial keratectomy with prophylactic intraoperative mitomycin-c

Development of late-onset subepithelial corneal haze after laser-assisted subepithelial keratectomy with prophylactic intraoperative mitomycin-c

Postoperative pharmacologic strategies to reduce the risk for post-LASEK haze involve the use of topical cor- ticosteroids, nonsteroidals, and ascorbic acid, among others. 5,9,20 Topical and systemic ascorbate have been shown to reduce the deleterious effects of UV-radiation ex- posure and free-radical injury to corneal tissue. 49–51 Cam- ellin 1 advocates the use of topical autologous serum 4 times daily for 1 week if the LASEK flap is disrupted, and Yee and Yee 20 apply autologous serum intraoperatively and postop- eratively. Lee et al. 52 report that fixing a strip of amniotic membrane at the inferior limbus immediately after LASEK in 94 eyes resulted in shorter reepithelialization times, bet- ter refractive and visual outcomes, and lower corneal haze than in eyes that had a bandage contact lens only. Addi- tional modalities such as keratocyte apoptosis blockers 29 and vector gene therapy 53 may assist with the treatment of subepithelial haze after LASEK in the future.
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