Publications by authors named "Alyson N Tukan"

6 Publications

  • Page 1 of 1

Comparison of 6.0 mm versus 6.5 mm Optical Zone on Visual Outcomes after LASIK.

J Clin Med 2021 Aug 24;10(17). Epub 2021 Aug 24.

Hoopes Vision Research Center, Hoopes Vision, Draper, UT 84020, USA.

Previous studies have demonstrated safety and efficacy using 6.0 and 6.5 mm optical zones in the WaveLight EX500 Excimer Laser System but have not evaluated if differing optical zone sizes influence refractive outcomes. This study examines visual outcomes between two study populations undergoing LASIK with either a 6.0 mm (1332 patients) or 6.5 mm (1332 patients) optical zone. Outcomes were further stratified by severity of myopia (low, moderate, and high) and astigmatism (low and high). Patients were matched by age and preoperative manifest sphere and cylinder. Postoperative measurements were then compared. The 6.5 mm group demonstrated better postoperative manifest refractive spherical equivalent (MRSE), manifest sphere, and absolute value of the difference in actual and target spherical equivalent refraction (|∆ SEQ|), within the total population, moderate myopia, and low astigmatism groups, but this did not lead to improved postoperative uncorrected distance visual acuity (UDVA) or best corrected distance visual acuity (CDVA). Though astigmatic correction and postoperative angle of error were similar between optical zone sizes, they were significantly worse with high myopia. Overall, this study demonstrates differences in visual outcomes between the 6.0 and 6.5 mm optical zone sizes that may warrant consideration; however, essentially, the results are comparable between them.
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http://dx.doi.org/10.3390/jcm10173776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8432203PMC
August 2021

Ectasia After Corneal Refractive Surgery: A Systematic Review.

Ophthalmol Ther 2021 Aug 20. Epub 2021 Aug 20.

Hoopes Vision Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT, 84020, USA.

Introduction: The incidence of ectasia following refractive surgery is unclear. This review sought to determine the worldwide rates of ectasia after photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) based on reports in the literature.

Methods: A systematic review was conducted according to modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Publications were identified by a search of eight electronic databases for relevant terms between 1984 and 2021. Patient characteristics and preoperative values including manifest refractive spherical refractive equivalent (MRSE), central corneal thickness (CCT), anterior keratometry, postoperative residual stromal bed (RSB), and percent tissue altered (PTA) were summarized. In addition, annual rates of each refractive surgery were determined, and incidence of post-refractive ectasia for each type was calculated using the number of ectatic eyes identified in the literature.

Results: In total, 57 eyes (70 eyes including those with preoperative risk factors for ectasia) were identified to have post-PRK ectasia, while 1453 eyes (1681 eyes including risk factors) had post-LASIK ectasia, and 11 eyes (19 eyes including risk factors) had post-SMILE ectasia. Cases of refractive surgery performed annually were estimated as 283,920 for PRK, 1,608,880 for LASIK, and 96,750 for SMILE. Reported post-refractive ectasia in eyes without preoperative identifiable risk factors occurred with the following incidences: 20 per 100,000 eyes in PRK, 90 per 100,000 eyes in LASIK, and 11 per 100,000 eyes in SMILE. The rate of ectasia in LASIK was found to be 4.5 times higher than that of PRK.

Conclusion: Post-refractive ectasia occurs at lower rates in eyes undergoing PRK than LASIK. Although SMILE appears to have the lowest rate of ectasia, the number of cases already reported since its recent approval suggests that post-SMILE ectasia may become a concern. Considering that keratoconus is a spectrum of disease, pre-existing keratoconus may play a larger role in postoperative ectasia than previously accounted for in the literature.
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http://dx.doi.org/10.1007/s40123-021-00383-wDOI Listing
August 2021

Toric Implantable Collamer Lens for the Treatment of Myopic Astigmatism.

Clin Ophthalmol 2021 6;15:2893-2906. Epub 2021 Jul 6.

Hoopes Vision Research Center, Hoopes Vision, Draper, UT, 84020, USA.

Purpose: To report visual outcomes following surgical correction of myopic astigmatism with Visian Toric implantable collamer lens (ICL) (STAAR Surgical, Monrovia, CA, USA) at a single tertiary refractive center in the United States.

Patients And Methods: Toric ICL was implanted in 96 eyes (55 patients) with mean preoperative sphere of -8.98 ± 3.04 diopters (D) and cylinder of -2.67 ± 1.02 D from December 2018 to February 2021. Primary visual outcomes of efficacy, safety, stability, predictability of refractive correction, and astigmatic analysis were reported at three and twelve months postoperatively. Secondary subjective outcomes included patient-reported dry eye symptoms and glare/halos at postoperative visits. Other secondary outcomes were biometric data and postoperative vault over time.

Results: At three and twelve months, 75 and 46 eyes were evaluated, respectively. At twelve months, the mean manifest refraction spherical equivalent (MRSE) was -0.23 ± 0.47 D with 93% achieving within ±1.00 D of target refraction. The manifest refractive cylinder (MRC) at twelve months was -0.73 ± 0.51 D, with 86% within ±1.00 D of target. Uncorrected distance visual acuity (UDVA) was 20/20 or better in 74% of eyes at twelve months. No patients lost ≥2 lines of corrected distance visual acuity (CDVA) at twelve months. The mean angle of error was -0.9 ± 10.2° at three months and -1.6 ± 12.8° at twelve months. One patient required bilateral lens rotation, four patients underwent secondary enhancement with LASIK/PRK, and seven patients underwent postoperative limbal relaxing incisions.

Conclusion: This initial single-site experience finds Toric ICL implantation for myopic astigmatism to be safe and effective. Patients can achieve markedly improved UDVA in a single surgery with stable vision over time and minimal adverse subjective symptoms.
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http://dx.doi.org/10.2147/OPTH.S321095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8274236PMC
July 2021

Intraocular Acrylic Allergy: Is it Something to Sneeze at?

Ophthalmol Ther 2021 Sep 14;10(3):393-396. Epub 2021 Jul 14.

University of Utah School of Medicine, Salt Lake City, UT, USA.

Cataract surgery is most commonly performed with acrylic intraocular lens (IOL) implantation. To date, there have been no reported cases of intraocular acrylic allergy despite increasing rates of acrylic-induced contact dermatitis elsewhere in the body. Concern regarding acrylate sensitization is gaining traction in the ophthalmology community. This commentary explores the lack of intraocular atopy and whether an acrylic allergy necessitates extensive preoperative consideration.
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http://dx.doi.org/10.1007/s40123-021-00374-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8319285PMC
September 2021

Clearing the Haze: Navigating Corneal Refractive Surgery in Patients with Posterior Polymorphous Corneal Dystrophy.

Ophthalmol Ther 2021 Sep 24;10(3):383-387. Epub 2021 Jun 24.

University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA.

Posterior polymorphous corneal dystrophy (PPCD) is a corneal disorder of the endothelium and Descemet's membrane. Although reports of corneal refractive surgery including laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE) in PPCD are minimal, these procedures have been shown to be safe and effective in this patient population. Proceeding with corneal refractive surgery in eyes with PPCD raises concerns regarding corneal integrity, including long-term biomechanical instability, risk of ectasia, endothelial cell loss, disease progression, and corneal decompensation. Thus, LASIK, PRK, and SMILE should be considered with caution. This commentary explores the patient characteristics associated with favorable surgical outcomes and factors that weigh against proceeding with refractive surgery.
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http://dx.doi.org/10.1007/s40123-021-00364-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8319270PMC
September 2021

Quantification of hair cortisol concentration in common marmosets (Callithrix jacchus) and tufted capuchins (Cebus apella).

Am J Primatol 2018 07 4;80(7):e22879. Epub 2018 Jun 4.

Department of Psychological and Brain Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts.

Quantifying cortisol concentration in hair is a non-invasive biomarker of long-term hypothalamic-pituitary-adrenal (HPA) activation, and thus can provide important information on laboratory animal health. Marmosets (Callithrix jacchus) and capuchins (Cebus apella) are New World primates increasingly used in biomedical and neuroscience research, yet published hair cortisol concentrations for these species are limited. Review of the existing published hair cortisol values from marmosets reveals highly discrepant values and the use of variable techniques for hair collection, processing, and cortisol extraction. In this investigation we utilized a well-established, standardized protocol to extract and quantify cortisol from marmoset (n = 12) and capuchin (n = 4) hair. Shaved hair samples were collected from the upper thigh during scheduled exams and analyzed via methanol extraction and enzyme immunoassay. In marmosets, hair cortisol concentration ranged from 2,710 to 6,267 pg/mg and averaged 4,070 ± 304 pg/mg. In capuchins, hair cortisol concentration ranged from 621 to 2,089 pg/mg and averaged 1,092 ± 338 pg/mg. Hair cortisol concentration was significantly different between marmosets and capuchins, with marmosets having higher concentrations than capuchins. The incorporation of hair cortisol analysis into research protocols provides a non-invasive measure of HPA axis activity over time, which offers insight into animal health. Utilization of standard protocols across laboratories is essential to obtaining valid measurements and allowing for valuable future cross-species comparisons.
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http://dx.doi.org/10.1002/ajp.22879DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6481164PMC
July 2018
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