The Experts below are selected from a list of 1923 Experts worldwide ranked by ideXlab platform
Nehal Maher Samy El Gendy - One of the best experts on this subject based on the ideXlab platform.
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predicting transepithelial Phototherapeutic Keratectomy outcomes using fourier domain optical coherence tomography
Cornea, 2014Co-Authors: Catherine Cleary, Yan Li, Maolong Tang, Nehal Maher Samy El Gendy, David HuangAbstract:PURPOSE: The aim of this study was to use Fourier domain optical coherence tomography to predict transepithelial Phototherapeutic Keratectomy outcomes. METHODS: This is a prospective case series. Subjects with anterior stromal corneal opacities underwent an excimer laser Phototherapeutic Keratectomy (PTK) combined with a photorefractive Keratectomy using the VISX S4 excimer laser (AMO, Inc, Santa Ana, CA). Preoperative and postoperative Fourier domain optical coherence tomography images were used to develop a simulation algorithm to predict treatment outcomes. Main outcome measures included preoperative and postoperative uncorrected distance visual acuities and corrected distance visual acuity. RESULTS: Nine eyes of 8 patients were treated. The nominal ablation depth was 75 to 177 μm centrally and 62 to 185 μm peripherally. Measured PTK ablation depths were 20% higher centrally and 26% higher peripherally, compared with those for laser settings. Postoperatively, the mean uncorrected distance visual acuity was 20/41 (range, 20/25-20/80) compared with 20/103 (range, 20/60-20/400) preoperatively. The mean corrected distance visual acuity was 20/29 (range, 20/15-20/60) compared with 20/45 (range, 20/30-20/80) preoperatively. The MRSE was +1.38 ± 2.37 diopters (D) compared with -2.59 ± 2.83 D (mean ± SD). The mean astigmatism magnitude was 1.14 ± 0.83 D compared with 1.40 ± 1.18 D preoperatively. Postoperative MRSE correlated strongly with ablation settings, central and peripheral epithelial thickness (r = 0.99, P < 0.00001). Central islands remained difficult to predict and limited visual outcomes in some cases. CONCLUSIONS: Optical coherence tomography measurements of opacity depth and 3-dimensional ablation simulation provide valuable guidance in PTK planning. Post-PTK refraction may be predicted with a regression formula that uses epithelial thickness measurements obtained by optical coherence tomography. The laser ablation rates described in this study apply only to the VISX laser.
G I W Duncker - One of the best experts on this subject based on the ideXlab platform.
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surgical outcome after Phototherapeutic Keratectomy in patients with tgfbi linked corneal dystrophies in relation to molecular genetic findings
Graefes Archive for Clinical and Experimental Ophthalmology, 2009Co-Authors: Claudia Gruenauerkloevekorn, Saskia Braeutigam, Ursula G Froster, G I W DunckerAbstract:Purpose To evaluate the correlation between surgical outcome after Phototherapeutic Keratectomy in patients with autosomal dominant transforming growth factor, beta-induced (TGFBI)-linked corneal dystrophies (CD) and molecular genetic findings regarding the TGFBI gene.
Steven E Wilson - One of the best experts on this subject based on the ideXlab platform.
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Phototherapeutic Keratectomy science and art
Journal of Refractive Surgery, 2017Co-Authors: Steven E Wilson, Gustavo K Marino, Carla S Medeiros, Marcony R SanthiagoAbstract:Purpose To describe, with videos, the principles of excimer laser Phototherapeutic Keratectomy (PTK) for the treatment of corneal scars, corneal surface irregularity, and recurrent corneal erosions. Methods Depending on the pathology in a treated cornea, the epithelium is removed either by transepithelial PTK ablation with the excimer laser or thorough scraping with a scalpel blade. Stromal PTK can be performed with or without photorefractive Keratectomy (PRK), depending on the refractive status of both eyes. Residual surface irregularity is treated with masking-smoothing PTK. Typically, 0.02% mitomycin C treatment is applied for 30 seconds to corneas treated with PTK for scars and surface irregularity. Results Transepithelial PTK with masking-smoothing typically improves corrected distance visual acuity in the eye even if the entire stromal opacity cannot be removed and can be used to debulk surface irregularity to facilitate subsequent therapeutic customized wavefront-guided or optical coherence tomography-guided PTK or PRK. PTK for recurrent erosion is performed after thorough mechanical epithelial debridement of redundant epithelial basement membrane (EBM) with a scalpel and should only include a dusting of excimer laser to remove residual EBM without inducing central irregular astigmatism or damaging limbal tissues. Meta-analyses are provided for PTK treatment for corneal scars, corneal dystrophies, and recurrent corneal erosions. Conclusions Excimer laser PTK is a highly effective treatment for superficial corneal scars, central corneal irregular astigmatism, and recurrent corneal erosions unresponsive to medical treatment or mechanical epithelial debridement alone. [J Refract Surg. 2017;33(3):203-210.].
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use of mitomycin c for Phototherapeutic Keratectomy and photorefractive Keratectomy surgery
Current Opinion in Ophthalmology, 2010Co-Authors: Ravindra A Shah, Steven E WilsonAbstract:PURPOSE OF REVIEW: Experience with mitomycin C (MMC) application during corneal surface ablation procedures such as Phototherapeutic Keratectomy and photorefractive Keratectomy has grown over the last decade. This review will highlight our understanding of the utility, mechanism of action, and safety profile of MMC. RECENT FINDINGS: MMC, although still off-label treatment for ophthalmic surgical uses, is now widely employed for photorefractive Keratectomy corrections of greater than four to six diopters. The last few years have seen the refractive surgery community embrace its use for virtually any corneal surgical procedure that carries an increased risk for haze formation. Experience has shown that MMC is highly effective at preventing haze and is well tolerated, with few reported complications. However, several recent reports have raised new questions about the long-term safety profile of MMC, especially with regard to decreased keratocyte and corneal endothelial cell populations noted months to years after surgery. New findings regarding the penetration of MMC to the endothelium and into the aqueous humor may lead surgeons to reassess appropriate dosing and patient selection when the drug is used for surgery. SUMMARY: The use of MMC has revitalized the application of surface ablation procedures such as photorefractive Keratectomy or Phototherapeutic Keratectomy for refractive and therapeutic treatments. Questions remain, however, regarding the long-term safety profile of MMC. A cautious approach to its continued use is advisable.
Peter J Mcdonnell - One of the best experts on this subject based on the ideXlab platform.
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Phototherapeutic Keratectomy for superficial corneal fibrosis after radial keratotomy
Journal of Cataract and Refractive Surgery, 2000Co-Authors: Yi Chiang Fong, Roy S Chuck, Walter J Stark, Peter J McdonnellAbstract:We report on 4 patients who developed superficial corneal fibrosis after radial keratotomy. All 4 were treated successfully with manual debridement of the epithelium and manual excision of the fibrous scar, followed by Phototherapeutic Keratectomy.
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clinical follow up of Phototherapeutic Keratectomy for treatment of corneal opacities
American Journal of Ophthalmology, 1993Co-Authors: Mauro Campos, Steven Nielsen, Karin Szerenyi, Jenny J Garbus, Peter J McdonnellAbstract:We performed Phototherapeutic Keratectomy with a 193-nm excimer laser on 18 sighted patients (18 eyes) to treat corneal opacities. The corneal opacities were caused by corneal dystrophies in five patients; corneal scars secondary to corneal ulcers in six patients; corneal scar secondary to trauma in four patients; and band keratopathy, atopy, or corneal calcification in three patients. Mean follow-up was eight months (range, two to 18 months). Corneal clarity improved in 14 of the 18 eyes (77.7%). Four patients, three with band keratopathy or calcification and one with postinfectious corneal scar, did not improve. Uncorrected visual acuity improved in 11 patients, did not improve in five patients (including the four patients in whom treatment failed), and decreased in another two patients, apparently because of an increase in irregular astigmatism. A hyperopic shift was observed in ten patients. None of the successfully treated eyes developed surface problems or recurrence of the disease during the follow-up. Phototherapeutic Keratectomy thus appears to be a safe and effective alternative to penetrating keratoplasty in some patients with selected anterior stromal opacities.
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Phototherapeutic Keratectomy with excimer laser for Reis-Bückler's corneal dystrophy.
Journal of Refractive Surgery, 1992Co-Authors: Peter J Mcdonnell, Theo SeilerAbstract:: Two patients with decreased visual acuity and recurrent epithelial erosions due to Reis-Buckler's corneal dystrophy underwent Phototherapeutic Keratectomy with the 193-nanometer excimer laser. Because the epithelial surface was relatively smooth prior to surgery, ablations were performed through an intact epithelium. Postoperatively, visual acuity was improved and symptoms of erosion decreased in both patients. Although no refractive shift was intended with the Phototherapeutic procedure, both patients were hyperopic following surgery. Superficial Keratectomy with the 193-nanometer excimer laser thus provides an alternative to conventional surgical Keratectomy.
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Unsuccessful excimer laser Phototherapeutic Keratectomy. Clinicopathologic correlation.
Archives of Ophthalmology, 1992Co-Authors: Jan M. Mcdonnell, Jenny J Garbus, Peter J McdonnellAbstract:• A 46-year-old man underwent Phototherapeutic Keratectomy with a 193-nm excimer laser in an attempt to remove a superficial corneal scar that had been present for 36 years. The scar proved to be resistant to ablation with the laser, while relatively normal stroma was easily ablated. Histopathologic examination of the corneal button removed 3 months after excimer laser surgery revealed absence of Bowman's membrane in the area of ablation, superficial stromal disorganization and scarring, raised nodules of collagenous tissue extending into the epithelium, and no calcification within the lesion. Ultrastructural examination was remarkable for irregularly oriented collagen fibers within the scar. The resistance of this lesion to excimer laser ablation appears to have been the consequence of marked differences in rates of ablation between normal stroma and the very longstanding scar.
David Huang - One of the best experts on this subject based on the ideXlab platform.
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predicting transepithelial Phototherapeutic Keratectomy outcomes using fourier domain optical coherence tomography
Cornea, 2014Co-Authors: Catherine Cleary, Yan Li, Maolong Tang, Nehal Maher Samy El Gendy, David HuangAbstract:PURPOSE: The aim of this study was to use Fourier domain optical coherence tomography to predict transepithelial Phototherapeutic Keratectomy outcomes. METHODS: This is a prospective case series. Subjects with anterior stromal corneal opacities underwent an excimer laser Phototherapeutic Keratectomy (PTK) combined with a photorefractive Keratectomy using the VISX S4 excimer laser (AMO, Inc, Santa Ana, CA). Preoperative and postoperative Fourier domain optical coherence tomography images were used to develop a simulation algorithm to predict treatment outcomes. Main outcome measures included preoperative and postoperative uncorrected distance visual acuities and corrected distance visual acuity. RESULTS: Nine eyes of 8 patients were treated. The nominal ablation depth was 75 to 177 μm centrally and 62 to 185 μm peripherally. Measured PTK ablation depths were 20% higher centrally and 26% higher peripherally, compared with those for laser settings. Postoperatively, the mean uncorrected distance visual acuity was 20/41 (range, 20/25-20/80) compared with 20/103 (range, 20/60-20/400) preoperatively. The mean corrected distance visual acuity was 20/29 (range, 20/15-20/60) compared with 20/45 (range, 20/30-20/80) preoperatively. The MRSE was +1.38 ± 2.37 diopters (D) compared with -2.59 ± 2.83 D (mean ± SD). The mean astigmatism magnitude was 1.14 ± 0.83 D compared with 1.40 ± 1.18 D preoperatively. Postoperative MRSE correlated strongly with ablation settings, central and peripheral epithelial thickness (r = 0.99, P < 0.00001). Central islands remained difficult to predict and limited visual outcomes in some cases. CONCLUSIONS: Optical coherence tomography measurements of opacity depth and 3-dimensional ablation simulation provide valuable guidance in PTK planning. Post-PTK refraction may be predicted with a regression formula that uses epithelial thickness measurements obtained by optical coherence tomography. The laser ablation rates described in this study apply only to the VISX laser.
