RESUMO
Approximately 41% of adults aged 18-24 years in the United States are enrolled in a college or university (1). Wearing a face mask can reduce transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (2), and many colleges and universities mandate mask use in public locations and outdoors when within six feet of others. Studies based on self-report have described mask use ranging from 69.1% to 86.1% among adults aged 18-29 years (3); however, more objective measures are needed. Direct observation by trained observers is the accepted standard for monitoring behaviors such as hand hygiene (4). In this investigation, direct observation was used to estimate the proportion of persons wearing masks and the proportion of persons wearing masks correctly (i.e., covering the nose and mouth and secured under the chin*) on campus and at nearby off-campus locations at six rural and suburban universities with mask mandates in the southern and western United States. Trained student observers recorded mask use for up to 8 weeks from fixed sites on campus and nearby. Among 17,200 observed persons, 85.5% wore masks, with 89.7% of those persons wearing the mask correctly (overall correct mask use: 76.7%). Among persons observed indoors, 91.7% wore masks correctly. The proportion correctly wearing masks indoors varied by mask type, from 96.8% for N95-type masks and 92.2% for cloth masks to 78.9% for bandanas, scarves, and similar face coverings. Observed indoor mask use was high at these six universities with mask mandates. Colleges and universities can use direct observation findings to tailor training and messaging toward increasing correct mask use.
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Máscaras/estatística & dados numéricos , Máscaras/normas , Saúde Pública/legislação & jurisprudência , Estudantes/psicologia , Universidades/legislação & jurisprudência , Adolescente , COVID-19/epidemiologia , COVID-19/prevenção & controle , Humanos , Estudantes/estatística & dados numéricos , Estados Unidos/epidemiologia , Adulto JovemRESUMO
PURPOSE: To objectively define the effective centration of myopic femtosecond laser-assisted LASIK ablation pattern, evaluate the difference between achieved versus planned excimer laser ablation centration, and compare these results from two different generations of an excimer laser system. METHODS: The study retrospectively evaluated 280 eyes subjected to myopic LASIK. Digital image analysis was performed on Scheimpflug sagittal curvature maps (difference of preoperative to postoperative). Centration was assessed via proprietary software digital analysis of the coordinate displacement between the achieved ablation geometric center and the planned ablation center, which was the corneal vertex. Results from two different excimer laser generations (Eye-Q 400 [140 eyes] and EX500 [140 eyes]; Alcon/WaveLight, Fort Worth, TX) were compared. RESULTS: Radial displacement was on average 360 ± 220 µm (range: 0 to 1,030 µm) in the Eye-Q 400 laser group and 120 ± 110 µm (range: 0 to 580 µm) in the EX500 laser group (P < .01). The percentage of eyes with displacement of greater than 300 µm was 52% in the Eye-Q 400 laser group and 4% in the EX500 laser group. CONCLUSIONS: Displacement of ablation pattern may depend on the laser platform used. The improvement in the efficiency of centration indicates that newer generation excimer lasers with faster eye tracking and active centration control appear to achieve a significantly more accurate centration of myopic ablation patterns. The authors propose this novel, objective technique for laser refractive surgeon evaluation may point out significant outcome measures not currently used in standard metrics of refractive laser efficiency.
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Astigmatismo/cirurgia , Substância Própria/cirurgia , Ceratomileuse Assistida por Excimer Laser In Situ/métodos , Lasers de Excimer/uso terapêutico , Miopia/cirurgia , Adolescente , Adulto , Topografia da Córnea , Humanos , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Retalhos Cirúrgicos , Adulto JovemRESUMO
PURPOSE: To investigate preoperative and postoperative anterior and posterior keratometry and simulated corneal astigmatism in keratoconic eyes treated with collagen cross-linking combined with anterior surface normalization by partial topography-guided excimer ablation (the Athens Protocol). METHODS: Anterior and posterior corneal keratometry were measured by Scheimpflug imaging for 267 untreated keratoconic eyes. Following treatment, they were assessed 1 year postoperatively. RESULTS: Before treatment, average anterior keratometric value was 47.06 ± 6.02 diopters (D) for flat and 51.24 ± 6.75 D for steep. The posterior keratometric values were -6.70 ± 0.99 D (flat) and -7.67 ± 1.15 D (steep). Anterior astigmatism was on average with-the-rule (-1.97 ± 6.21 D), whereas posterior astigmatism was against-the-rule (+0.53 ± 1.02 D). The posterior and anterior astigmatism were highly correlated (r(2) = 0.839). After treatment, anterior keratometric values were 43.97 ± 5.81 D (flat) and 46.55 ± 6.82 D (steep). Posterior keratometric values were -6.58 ± 1.05 D (flat) and -7.69 ± 1.22 D (steep). Anterior astigmatism was on average with-the-rule (-1.56 ± 3.80 D), whereas posterior astigmatism was against-the-rule (+0.45 ± 1.29 D). The statistically significant (P < .05) keratometric changes indicated anterior surface flattening -3.09 ± 2.67 D (flat) and -4.19 ± 2.96 D (steep). The posterior keratometric changes were not statistically significant (P > .05). CONCLUSIONS: Before treatment, there was a strong correlation between posterior and anterior corneal astigmatism. After treatment, statistically significant anterior keratometric values flattened. The posterior surface keratometric values did not demonstrate statistically significant postoperative change: there was minimal posterior change, despite the significant anterior surface normalization.
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Córnea/fisiopatologia , Topografia da Córnea , Reagentes de Ligações Cruzadas/uso terapêutico , Ceratocone/terapia , Ceratectomia Fotorrefrativa , Refração Ocular/fisiologia , Adulto , Astigmatismo/fisiopatologia , Colágeno/metabolismo , Terapia Combinada , Substância Própria/metabolismo , Feminino , Humanos , Ceratocone/metabolismo , Ceratocone/fisiopatologia , Masculino , Pessoa de Meia-Idade , Fármacos Fotossensibilizantes/uso terapêutico , Riboflavina/uso terapêutico , Resultado do Tratamento , Raios Ultravioleta , Adulto JovemRESUMO
PURPOSE: To map corneal and epithelial layer thickness changes following cataract removal surgery employing a spectral-domain anterior-segment optical coherence tomography system. METHODS: Corneal and epithelial thickness three-dimensional profile distribution was clinically imaged preoperatively and up to 3 months postoperatively with anterior-segment optical coherence tomography in 116 consecutive cases. Descriptive statistics investigated central corneal thickness, minimum corneal thickness, and epithelial thickness at the central 2-mm area, the mean over the 6-mm area, and mid-peripherally at 5-mm ring. RESULTS: In comparison to preoperative, the center, mean, and mid-peripheral epithelial thickness at the first postoperative day increased by +2.84, +2.35, and +2.25 µm, respectively (P < .001, < .001, and = .0014). One week postoperatively, the epithelial thickness differences were -1.91, -2.62, and -2.76 µm, respectively (P < .001, < .001, and < .001). Four weeks postoperatively, the differences of -0.20, -0.59, and -0.66 µm for the center, mean, and mid-periphery were not statistically significant (P = .6449, .1512, and .11097). Three months postoperatively, the differences were -0.05, -0.28, and -0.09 µm, respectively (P = .8722, .2341, and .6431). CONCLUSIONS: Qualitative and quantitative assessment of epithelial remodeling following cataract removal indicated that the early (1 day and 1 week) corneal and epithelial thickness returned to the preoperative baseline 4 weeks postoperatively. This in vivo epithelial and corneal screening with optical coherence tomography can be valuable for the postoperative assessment and follow-up.
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Epitélio Corneano/fisiologia , Implante de Lente Intraocular , Facoemulsificação , Tomografia de Coerência Óptica , Idoso , Idoso de 80 Anos ou mais , Córnea/anatomia & histologia , Paquimetria Corneana , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Estudos ProspectivosRESUMO
PURPOSE: To investigate refractive, topometric, pachymetric, and visual rehabilitation changes induced by anterior surface normalization for keratoconus by partial topography-guided excimer laser ablation in conjunction with accelerated, high-fluence cross-linking. METHODS: Two hundred thirty-one keratoconic cases subjected to the Athens Protocol procedure were studied for visual acuity, keratometry, pachymetry, and anterior surface irregularity indices up to 3 years postoperatively by Scheimpflug imaging (Oculus Optikgeräte GmbH, Wetzlar, Germany). RESULTS: Mean visual acuity changes at 3 years postoperatively were +0.38 ± 0.31 (range: -0.34 to +1.10) for uncorrected distance visual acuity and +0.20 ± 0.21 (range: -0.32 to +0.90) for corrected distance visual acuity. Mean K1 (flat meridian) keratometric values were 46.56 ± 3.83 diopters (D) (range: 39.75 to 58.30 D) preoperatively, 44.44 ± 3.97 D (range: 36.10 to 55.50 D) 1 month postoperatively, and 43.22 ± 3.80 D (range: 36.00 to 53.70 D) up to 3 years postoperatively. The average Index of Surface Variance was 98.48 ± 43.47 (range: 17 to 208) pre-operatively and 76.80 ± 38.41 (range: 7 to 190) up to 3 years postoperatively. The average Index of Height Decentration was 0.091 ± 0.053 µm (range: 0.006 to 0.275 µm) preoperatively and 0.057 ± 0.040 µm (range: 0.001 to 0.208 µm) up to 3 years postoperatively. Mean thinnest corneal thickness was 451.91 ± 40.02 µm (range: 297 to 547 µm) preoperatively, 353.95 ± 53.90 µm (range: 196 to 480 µm) 1 month postoperatively, and 370.52 ± 58.21 µm (range: 218 to 500 µm) up to 3 years postoperatively. CONCLUSIONS: The Athens Protocol to arrest keratectasia progression and improve corneal regularity demonstrates safe and effective results as a keratoconus management option. Progressive potential for long-term flattening validates using caution in the surface normalization to avoid overcorrection.
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Topografia da Córnea , Reagentes de Ligações Cruzadas/uso terapêutico , Ceratocone/tratamento farmacológico , Refração Ocular/fisiologia , Acuidade Visual/fisiologia , Adolescente , Adulto , Colágeno/metabolismo , Córnea/fisiopatologia , Paquimetria Corneana , Substância Própria/metabolismo , Feminino , Humanos , Ceratocone/fisiopatologia , Masculino , Pessoa de Meia-Idade , Fármacos Fotossensibilizantes/uso terapêutico , Riboflavina/uso terapêutico , Adulto JovemRESUMO
PURPOSE: To evaluate epithelial thickness profile changes following myopic femtosecond laser-assisted LASIK in relation to the degree of myopia corrected, evaluated with a spectral-domain anterior-segment optical coherence tomography system. METHODS: Sixty-one consecutive cases were observed for corneal epithelial thickness distribution preoperatively and at 1 day, 1 week, 1 month, and 1 year postoperatively. Epithelial thickness mapping was obtained with a spectral-domain optical coherence tomography system (Optovue Inc., Fremont, CA). Descriptive statistics investigated epithelial thickness at the central 2-mm area, the mean over the central 6-mm area, and mid-peripherally at the 5-mm ring area. RESULTS: Preoperatively, the pupil center epithelial thickness was 51.67 ± 2.57 µm (range: 45 to 56 µm), mean was 51.76 ± 2.66 µm (range: 45 to 57 µm), and mid-periphery was 51.78 ± 2.71 µm (range: 46 to 57 µm). Compared to the preoperative values, the epithelial thickness for the center, mean, and mid-periphery was −0.30, +1.07, and +1.35 µm at 1 week, +1.58, +2.88, and +3.31 µm at 1 month (P = .0036, < .001, and < .001), and +1.42, +2.90, and +3.19 µm at 1 year postoperatively (P = 0.146, < .001, and < .001), respectively. The correlation analysis between the epithelial thickness increase and the spherical equivalent of myopic correction showed a trend toward epithelial thickness increase with the amount of myopic ablation, particularly at the mid-peripheral 5-mm area. CONCLUSIONS: In this comprehensive study of postoperative corneal epithelial thickness remodeling following femtosecond laser-assisted myopic LASIK correction, an increase at the 1-month and up to 1-year postoperative interval suggested postoperative epithelial activity in connection to the extent of ablation.
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Células Epiteliais/patologia , Epitélio Corneano/patologia , Ceratomileuse Assistida por Excimer Laser In Situ , Lasers de Excimer/uso terapêutico , Miopia/cirurgia , Adolescente , Adulto , Paquimetria Corneana , Feminino , Seguimentos , Humanos , Masculino , Miopia/fisiopatologia , Período Pós-Operatório , Refração Ocular/fisiologia , Tomografia de Coerência Óptica , Adulto JovemRESUMO
PURPOSE: To evaluate safety, efficacy, ergonomy, and refractive and keratometric stability in high myopia LASIK procedures using a novel femtosecond and excimer laser surgery platform. METHODS: One hundred sixteen eyes in consecutive cases of high myopic LASIK ( ≥ -6.00 diopters [D]) with the Alcon-WaveLight FS200 femtosecond and EX500 excimer lasers (Alcon Laboratories, Fort Worth, TX) were evaluated preoperatively and postoperatively for the following parameters: refractive error, corrected distance visual acuity, uncorrected distance visual acuity, spherical equivalent correction, keratometry (with Placido topography and Scheimpflug tomography), and refractive astigmatism. Average follow-up time was 6.2 months (range: 3 to 12 months). RESULTS: Postoperative average refractive error was -0.37, -0.43, and -0.25 D for the 3-, 6-, and 12-month period, compared to -7.67 ± 1.55 D preoperatively. At 3, 6, and 12 months postoperatively 94%, 96.3%, and 100% of eyes, respectively, were within 1.0 D defocus equivalent. Postoperative refractive astigmatism was -0.21, -0.21, -0.13 D for the 3-, 6-, and 12-month period compared to -1.07 ± 1.91 D preoperatively. The proportion of eyes with postoperative astigmatism within 0.25 D was 85.3%, 81.5%, and 100%, for the 3-, 6-, and 12-month visit, respectively. Keratometric stability was within 0.22 D after the 12-month visit. There was no epithelial ingrowth or diffuse lamellar keratitis in any case. CONCLUSIONS: Clinical outcomes with this technique and technology appear to be promising in high level uncorrected visual rehabilitation of high myopia. There was small regression potential in the sample evaluated.
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Substância Própria/cirurgia , Ceratomileuse Assistida por Excimer Laser In Situ/métodos , Lasers de Excimer/uso terapêutico , Miopia Degenerativa/cirurgia , Adolescente , Adulto , Astigmatismo/fisiopatologia , Topografia da Córnea , Feminino , Seguimentos , Humanos , Ceratomileuse Assistida por Excimer Laser In Situ/efeitos adversos , Masculino , Pessoa de Meia-Idade , Miopia Degenerativa/fisiopatologia , Refração Ocular/fisiologia , Estudos Retrospectivos , Resultado do Tratamento , Acuidade Visual/fisiologia , Adulto JovemRESUMO
PURPOSE: To evaluate the potential influence of corneal cross-linking (CXL) with ultraviolet-A light and riboflavin in keratoconic eyes on several objective parameters of dry eye syndrome. METHODS: This prospective single center study included 30 consecutive eyes of 16 patients that underwent CXL with riboflavin and ultraviolet-A treatment (epithelial removal, 30 minutes soaking with riboflavin, 30 minutes of illumination with 365 nm, 3 mW/cm(2), 5 cm distance). Several dry eye syndrome parameters were evaluated preoperatively and 3 and 6 months after the procedure: intra-individual comparison of fluorescein and Rose bengal staining, height of tear film meniscus, and tear film break-up time. RESULTS: Pathologic staining (more than 10 point-shaped areas or diffuse staining) with fluorescein was evident before CXL in 1 eye, 3 months after CXL in 1 eye, and 6 months after CXL in 1 eye. Rose bengal staining 3 and 6 months postoperatively was comparable to preoperative staining. Tear film height was reduced in 2 eyes before CXL and in 4 eyes 3 months postoperatively, and was normal in all eyes after 6 months. The number of eyes with reduced tear film break-up time was not significantly changed. CONCLUSIONS: CXL had no significant impact on several parameters of dry eye syndrome 3 and 6 months postoperatively.
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Reagentes de Ligações Cruzadas/uso terapêutico , Síndromes do Olho Seco/tratamento farmacológico , Ceratocone/tratamento farmacológico , Riboflavina/uso terapêutico , Adulto , Topografia da Córnea , Síndromes do Olho Seco/complicações , Síndromes do Olho Seco/patologia , Feminino , Seguimentos , Humanos , Ceratocone/complicações , Ceratocone/patologia , Masculino , Pessoa de Meia-Idade , Fotoquimioterapia , Fármacos Fotossensibilizantes/uso terapêutico , Estudos Prospectivos , Resultado do Tratamento , Raios Ultravioleta , Acuidade Visual , Adulto JovemRESUMO
PURPOSE: To compare and correlate central corneal thickness (CCT), anterior chamber depth (ACD), and keratometric (flat and steep K) measurements using two anterior segment imaging methods, a Scheimpflug camera system (Oculyzer II [Oculus Optikgeräte GmbH]) and a partial coherence biometry system (WaveLight OB820 [Alcon Laboratories Inc]) in eyes undergoing cataract surgery. METHODS: Ninety patients (mean age: 66±13 years [range: 32 to 88 years]) underwent preoperative measurement of CCT, ACD, and keratometric measurements by Scheimpflug tomography (Oculyzer II) and optical low coherence reflectometry (WaveLight OB820). Interdevice agreement and correlation between the two techniques were assessed. RESULTS: All measurements were highly correlated and showed no clinically significant difference between methods. Mean CCT was 554.21±39.07 µm and 546.59±37.75 µm for the Oculyzer II and WaveLight OB820, respectively (R²=0.9268). Mean ACD was 2.63±0.44 mm and 2.63±0.43 mm for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9488). The principal meridian keratometric values were also highly correlated. Mean flat K was 42.88±1.50 diopters (D) and 42.96±1.40 D for the Oculyzer II and WaveLight OB820, respectively (R²=0.8741). Mean steep K was 44.08±1.79 D and 44.26±1.95 D for the Oculyzer II and WaveLight OB820, respectively (R(2)=0.9159). CONCLUSIONS: Our data show that the Oculyzer II and WaveLight OB820 provide measurements that are in agreement with published values for CCT and ACD in patients. Excellent agreement for CCT and ACD was found between the two devices, as demonstrated by a high degree of correlation and linearity, in addition to minimal bias. Thus, CCT, ACD, and K measurements by these instruments can both be used in clinical preparation, and their agreement is an ensuring precision factor for cataract and refractive surgeons.
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Câmara Anterior/patologia , Extração de Catarata , Córnea/patologia , Técnicas de Diagnóstico Oftalmológico/instrumentação , Período Pré-Operatório , Adulto , Idoso , Idoso de 80 Anos ou mais , Biometria/instrumentação , Feminino , Humanos , Interferometria/instrumentação , Masculino , Pessoa de Meia-Idade , Fotografação/instrumentação , Reprodutibilidade dos TestesRESUMO
PURPOSE: To study the effects on visual performance of a novel custom hydrogel contact lens, which employs a correction for vertical coma aberration, in keratoconic eyes. METHODS: Six subjects (8 eyes) with mild or moderate keratoconus were recruited for the study. Preliminary measurements included corneal topography, wavefront aberrometry, subjective refraction, visual acuity (VA) and 50% contrast VA. Based on the aberrometry data, customized lenses were made and fitted to the subjects. Evaluation of the on-eye performance of the lenses was carried out, including wavefront aberrometry, over-refraction, VA and 50% contrast VA. In two of the subjects, both eyes were fitted with the customized lenses, and binocular performance was evaluated. RESULTS: Monocular visual performance with a 4 mm pupil, with the lenses worn, was improved, and reached the mean values of -0.003 (LogMar units) of 100% high contrast VA, and 0.049 (in LogMar units) of 50% contrast VA. Vertical coma aberration and total higher-order aberrations (HOAs) were reduced (naked eyes: -0.64 +/- 0.21 root mean square (rms) of vertical coma and 0.86 +/- 0.15 rms of total HOAs; with the lenses worn: -0.29 +/- 0.23 rms of vertical coma and 0.57 +/- 0.17 rms of total HOAs, all for a 4 mm pupil). Binocular VA results from two of the subjects were on average -0.040 (LogMar units) 100% high contrast acuity and -0.060 (LogMar units) 50% contrast visual acuity. CONCLUSIONS: Customized hydrogel contact lenses implementing correction of vertical coma, have been found to improve both monocular and binocular visual performance of eyes affected with mild or moderate keratoconus.
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Lentes de Contato/estatística & dados numéricos , Hidrogel de Polietilenoglicol-Dimetacrilato , Ceratocone/reabilitação , Refração Ocular/fisiologia , Acuidade Visual/fisiologia , Topografia da Córnea/métodos , Desenho de Equipamento , Humanos , Ceratocone/fisiopatologiaRESUMO
Dry eye is a multifactorial, progressive, and chronic disease of the tears and ocular surface. The disease is multi-factorial and has intermittent symptoms. Discomfort, visual disturbance, tear film instability with potential damage to the ocular surface, and increased tear film osmolarity are known associates. Dry eye is a common clinical problem for eye-care providers worldwide and there is a large number of clinical investigative techniques for the evaluation of dry eye. Despite this, however, there is no globally accepted guideline for dry eye diagnosis and none of the available tests may hold the title of the 'gold standard'. The majority of the techniques involved in the diagnosis of the disease, particularly for its early stages, has a large degree of subjectivity. The purpose of this article is to review existing dry eye investigative techniques and to present a new objective dry eye screening technique based on optical coherence tomography.
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BACKGROUND: Femtosecond-laser assisted clear cornea cataract surgery may hold promise in safer and more effective procedures. We decided to perform a comparative study to standard manual incision phacoemulsification surgery. METHODS: This is a single-center, single-intervention, and prospective comparative data evaluation of 133 consecutive cases subjected to cataract surgery. Group-A (Phaco), manual capsulorhexis & ultrasound phacoemulsification (n = 66); Group-B femtosecond-laser assisted capsulorhexis and lens fragmentation (n = 67), employing the LenSx laser (Alcon Surgical, Ft. Worth, TX). All cases were evaluated for refraction, visual acuity, keratometry, tomography, pachymetry, endothelial cell counts, intraocular pressure, and type of intraocular lens (IOL) implanted. The groups were matched for age, gender, pre-operative vision metrics, and cataract grade, and were followed up to 1 year. RESULTS: In group-A post-operative uncorrected distance visual acuity (UDVA) was 20/20 or better in 61.5 % and 20/25 or better in 78.5 % of the eyes. The femtosecond laser group-B had improved outcomes (p = 0.075 and p = 0.042, respectively): post-operative UDVA was 20/20 or better in 62.7 % of the eyes and 20/25 or better in 85.1 %. Linear regression scatterplots of achieved versus attempted spherical equivalent had excellent regression coefficients (r (2) = 0.983 in group-A and 0.979 in group-B). There were 75.2 % cases in group-A and 80.6 % in group-B (p = 0.8732) within ±0.50 D of targeted refractive equivalent. Slight trend of under-correction was noted in group-A. Average residual manifest cylinder in the toric subgroup-A was -0.50 D (95 % Limit-of-Agreement (LoA) = -0.78 D), and in toric subgroup-B -0.45 D (LoA = -0.45 D). CONCLUSIONS: Mean spherical equivalent refraction and visual acuity are comparable with laser cataract surgery compared with manual capsulorhexis & ultrasound phacoemulsification. Improved astigmatism correction may be among the benefits of femtosecond laser-assisted cataract surgery. Transient corneal edema may be a first day transient disadvantage in femtosecond laser-assisted cataract surgery.
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PURPOSE: To evaluate ex vivo the possible difference in corneal cross-linking (CXL) biomechanical effect of different ultraviolet-A (UV-A) irradiances. METHODS: The study involved 25 human donor corneas, randomly allocated to 5 groups (n = 5 each). CXL was applied with UV-A irradiances of 3, 9, 18, 30, and 45 mW/cm2, maintaining equal cumulative energy dose of 5.4 J/cm2. UV-A was delivered on half of the cornea. The nonirradiated halves served as controls. Specimens were subjected to collagenase-A enzymatic digestion. The time to complete dissolution in each specimen was recorded. RESULTS: Time to dissolution in group-A (3 mW/cm2 for 30 minutes) was 321 ± 13.4 minutes (range: 300-330) compared with 171 ± 8.2 (range: 165-180) for their control. In group-B (9 mW/cm2 for 10 minutes), it was 282 ± 19.6 minutes (range: 270-315) compared with 177 ± 6.7 (165-180) for their control. In group-C (18 mW/cm2 for 5 minutes), it was 267 ± 19.6 minutes (range: 240-285) compared with 177 ± 7.7 (range: 165-180) for their control. In group-D (30 mW/cm2 for 3 minutes), it was 252 ± 12.5 minutes (range: 240-270) compared with 180 ± 10.6 minutes (range: 165-195) for their control. In group-E (45 mW/cm2 for 2 minutes), it was 204 ± 17.1 minutes (range: 180-225) compared with 186 ± 8.2 minutes (range: 180-195) for their control. CONCLUSIONS: The data in this ex vivo human corneal study indicate that the biomechanical effect of CXL studied by resistance to enzymatic digestion in human corneas is comparable between irradiances of 9, 18 and 30 mW/cm and seems to be reduced at a fluence of 45 mW/cm2.
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Colágeno/metabolismo , Colagenases/farmacologia , Córnea/fisiologia , Reagentes de Ligações Cruzadas , Fármacos Fotossensibilizantes/farmacologia , Riboflavina/farmacologia , Terapia Ultravioleta , Idoso , Fenômenos Biomecânicos , Córnea/efeitos dos fármacos , Substância Própria/efeitos dos fármacos , Substância Própria/metabolismo , Relação Dose-Resposta à Radiação , Elasticidade/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doadores de TecidosRESUMO
BACKGROUND: To compare intraocular pressure (IOP) changes following topical dexamethasone administration for 1 month in keratoconic versus normal eyes. METHODS: This is a retrospective, single-center, non-randomized case series evaluation of 350 eyes. Two groups were formed: normal/control Group A (nA =73), eyes that underwent excimer laser photorefractive keratectomy; and keratoconic (KCN) Group B (nB =277), eyes that were subjected to partial laser photorefractive keratectomy combined with collagen cross-linking (The Athens Protocol). All eyes received the same post-operative regimen of topical dexamethasone 0.1 % for at least 1 month. Goldmann applanation tonometry IOP readings and central corneal thickness (CCT) measurements were monitored. Cases with induced ocular hypertension (OHT, defined as post-operative IOP higher than 21 mmHg), were identified and correlated to refractive procedure, gender, and corneal thickness. RESULTS: At 4 weeks postoperatively, OHT was noted on 27.4 % (20 /73 eyes) in Group A, and 43.7 % (121 /277 eyes) in KCN Group B, (p <0.01). Six months post-operatively (following 5-months of discontinuing topical dexamethasone treatment and commencing treatment of IOP-lowering medications), OHT rate was 1.8 % in Group A and 3.9 % in the KCN Group B. CONCLUSION: This study demonstrates a potentially significant pre-disposition of keratoconic eyes to the development of steroid-induced OHT.
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PURPOSE: To evaluate and investigate the distribution and repeatability of anterior corneal surface astigmatism measurements (axis and magnitude) using a novel corneal topographer. METHODS: Anterior corneal surface astigmatism was investigated in a total of 195 eyes using a novel multicolored spot reflection topographer (Cassini; i-Optics). Two patient groups were studied, a younger-age group A and an older-age group B. Three consecutive acquisitions were obtained from each eye. The repeatability of measurement was assessed using Bland-Altman plot analysis and is reported as the coefficient of repeatability. RESULTS: Group A (average age 34.3 years) had on average with-the-rule astigmatism, whereas the older-age group B (average age 72.3 years) had on average against-the-rule astigmatism. Average astigmatism magnitude measurement repeatability in group A was 0.4 diopters (D) and in group B 0.4 D. Average astigmatism axis measurement repeatability in group A was 5.4 degrees and in group B 5.5 degrees. The axis measurement repeatability improved with increasing magnitude of astigmatism: in the subgroups with astigmatism between 3.0 and 6.0 D, the axis repeatability was 1.4 degrees (group A) and 1.2 degrees (group B), whereas in the subgroups with astigmatism larger than 6.0 D, the repeatability was 1.1 and 0.6 degrees, respectively. CONCLUSIONS: This novel corneal topography device seems to offer high precision in reporting corneal astigmatism. This study reaffirms the established trend of a corneal astigmatism shift from an average "with-the-rule" to "against-the-rule" with aging.
Assuntos
Astigmatismo/diagnóstico , Córnea/patologia , Topografia da Córnea/instrumentação , Adolescente , Adulto , Idoso , Envelhecimento/fisiologia , Astigmatismo/fisiopatologia , Cor , Feminino , Seguimentos , Humanos , Luz , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes , Adulto JovemRESUMO
PURPOSE: To investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK) and normal population, as well as cohorts of high and irregular astigmatism such as keratoconic eyes, and keratoconic eyes following corneal collagen cross-linking, employing a novel corneal reflection topography device. METHODS: Steep and flat keratometry and astigmatism axis measurement repeatability was investigated employing a novel multicolored-spot reflection topographer (Cassini) in four study groups, namely a post myopic LASIK-treated Group A, a keratoconus Group B, a post-CXL keratoconus Group C, and a control Group D of routine healthy patients. Three separate, maps were obtained employing the Cassini, enabling investigation of the intra-individual repeatability by standard deviation. Additionally we investigated in all groups,the Klyce surface irregularity indices for keratoconus, the SAI (surface asymmetry index) and the SRI (surface regularity index). RESULTS: Flat keratometry repeatability was 0.74±0.89 (0.03 to 5.26) diopters (D) in the LASIK Group A, 0.88±1.45 (range minimum to maximum, 0.00 to 7.84) D in the keratoconic Group B, and 0.71±0.94 (0.02 to 6.23) D in the cross-linked Group C. The control Group D had flat keratometry repeatability 0.36±0.46 (0.00 to 2.71) D. Steep keratometry repeatability was 0.64±0.82 (0.01 to 4.81) D in the LASIK Group A, 0.89±1.22 (0.02 to 7.85) D in the keratoconic Group B, and 0.93±1.12 (0.04 to 5.93) D in the cross-linked Group C. The control Group D had steep keratometry repeatability 0.41±0.50 (0.00 to 3.51) D. Axis repeatability was 3.45±1.62° (0.38 to 7.78°) for the LASIK Group A, 4.12±3.17° (0.02 to 12.13°) for the keratoconic Group B, and 3.20±1.99° (0.17 to 8.61°) for the cross-linked Group C. The control Group D had axis repeatability 2.16±1.39° (0.05 to 5.86°). The SAI index measurement repeatability was 0.33±0.40 (0.01 to 2.31) in the post-LASIK Group A, 0.39±0.75 (0.00 to 7.15) in the keratoconic Group B, and 0.43±0.56 (0.05 to 3.50) in the keratoconus post-CXL Group C. The control group had SAI measurement repeatability of 0.26±0.30 (0.00 to 2.39). The SRI index repeatability was 0.22±0.17 (0.01 to 0.96) for post-LASIK Group A, 0.20±0.18 (0.00 to 1.07) in keratoconic Group B, and 0.13±0.09 (0.00 to 0.45) in the keratoconus post-CXL Group C. The control Group D had SRI measurement repeatability of 0.23±0.16 (0.00 to 0.75). CONCLUSION: This novel corneal topography device appears to offer very high specificity in estimating corneal keratometry and specific corneal irregularity indices, even in topographically challenging corneas such as LASIK treated, keratoconic, and cross-linked.
RESUMO
PURPOSE: To comparatively investigate the efficacy of the enhanced Athens Protocol procedure guided by novel Placido-derived topography with cyclorotation compensation (the cyclorotation adjusted group) to similar cases guided by Scheimpflug-derived tomography without cyclorotation compensation (the non-cyclorotation adjusted group). METHODS: Two groups were evaluated: the cyclorotation adjusted group (n = 110 eyes) and the non-cyclorotation adjusted group (n = 110 eyes). Analysis was based on digital processing of Scheimpflug imaging derived curvature difference maps preoperatively and 3 months postoperatively. The vector (r, Ï) corresponding to the steepest corneal point (cone) on the preoperative surgical planning map (rp, Ïp) and on the curvature difference map (rd, Ïd) were computed. The differences between the peak topographic angular data (ΔÏ = |Ïp - Ïd|) and weighted angular difference (WΔÏ = ΔÏ × Δr) were calculated. RESULTS: For the cyclorotation adjusted group, ΔÏ was 7.18° ± 7.53° (range: 0° to 34) and WΔÏ was 3.43 ± 4.76 mm (range: 0.00 to 21.41 mm). For the non-cyclorotation adjusted group, ΔÏ was 14.50° ± 12.65° (range: 0° to 49°) and WΔÏ was 10.23 ± 15.15 mm (range: 0.00 to 80.56 mm). The cyclorotation adjusted group appeared superior to the non-cyclorotation adjusted group, in both the smaller average angular difference between attempted to achieved irregular curvature normalization and in weighted angular difference, by a statistically significant margin (ΔÏ: P = .0058; WΔÏ: P = .015). CONCLUSIONS: This study suggests that employment of the novel Placido-derived topographic data of highly irregular corneas, such as in keratoconus, treated with topography-guided profile with cyclorotation compensation leads to markedly improved cornea normalization.
Assuntos
Topografia da Córnea/métodos , Ceratocone/terapia , Lasers de Excimer/uso terapêutico , Fotoquimioterapia , Ceratectomia Fotorrefrativa/métodos , Cirurgia Assistida por Computador , Adolescente , Adulto , Colágeno/metabolismo , Terapia Combinada , Substância Própria/metabolismo , Feminino , Seguimentos , Humanos , Ceratocone/tratamento farmacológico , Ceratocone/metabolismo , Ceratocone/cirurgia , Masculino , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/uso terapêutico , Estudos Retrospectivos , Riboflavina/uso terapêutico , Raios Ultravioleta , Acuidade Visual/fisiologia , Adulto JovemRESUMO
PURPOSE: To evaluate the safety, efficacy, and refractive and keratometric stability of myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence corneal collagen crosslinking (CXL) compared with the outcomes of standard femtosecond LASIK. SETTING: Private clinical practice, Athens, Greece. DESIGN: Consecutive randomized prospective comparative study. METHODS: Eyes that had myopic LASIK or myopic LASIK with concurrent high-fluence CXL were evaluated preoperatively and up to 2 years postoperatively for manifest refraction spherical equivalent (MRSE), refractive astigmatism, visual acuity, corneal keratometry (K), and endothelial cell count. RESULTS: One hundred forty consecutive eyes had myopic LASIK; 65 of the eyes were treated additionally with CXL. In the LASIK-CXL eyes, the mean postoperative MRSE was -0.18 diopter (D) ± 17.0 (SD) from -6.67 ± 2.14 D preoperatively. The postoperative flat K was 37.67 D from 43.92 D, and the steep K was 38.38 D from 45.15 D. The correlation coefficient of SE correction predictability was 0.975. In the LASIK-only eyes, the mean postoperative MRSE was -0.32 ± 0.24 D from -5.49 ± 1.99 D preoperatively. The flat K was 38.04 D from 43.15 D, and the steep K was 38.69 D from 44.03 D. The correlation coefficient of SE correction predictability was 0.968. The differences between the 2 groups at the 20/20 and 20/25 levels were statistically significant (P = .045 and P = .039, respectively). CONCLUSION: Two-year results indicate that the application of prophylactic CXL concurrently with high-myopic LASIK appears to improve refractive and keratometric stability, presumably by affecting corneal biomechanical properties. FINANCIAL DISCLOSURE: Dr. Kanellopoulos is a consultant to Alcon Surgical, Inc., Wavelight Laser Technologie AG, Allergan, Inc., Avedro, Inc., and i-Optics Corp. Dr. Asimellis has no financial or proprietary interest in any material or method mentioned.
Assuntos
Colágeno/metabolismo , Substância Própria/metabolismo , Reagentes de Ligações Cruzadas , Ceratomileuse Assistida por Excimer Laser In Situ/métodos , Lasers de Excimer/uso terapêutico , Miopia Degenerativa/terapia , Fármacos Fotossensibilizantes/uso terapêutico , Adolescente , Adulto , Contagem de Células , Terapia Combinada , Paquimetria Corneana , Endotélio Corneano/patologia , Feminino , Seguimentos , Humanos , Lasers de Excimer/efeitos adversos , Masculino , Miopia Degenerativa/tratamento farmacológico , Miopia Degenerativa/fisiopatologia , Miopia Degenerativa/cirurgia , Fármacos Fotossensibilizantes/efeitos adversos , Estudos Prospectivos , Refração Ocular/fisiologia , Riboflavina/uso terapêutico , Retalhos Cirúrgicos , Tomografia de Coerência Óptica , Resultado do Tratamento , Acuidade Visual/fisiologia , Adulto JovemRESUMO
PURPOSE: To compare postoperative changes in apparent photopic and mesopic pupil size and centration in relation to cornea reflection landmarks after cataract surgery. SETTING: LaserVision.gr Clinical and Research Eye Institute, Athens, Greece. DESIGN: Prospective consecutive case study. METHODS: Pupils were imaged for pupil size and corneal vertex location before and 1-month after cataract surgery. Digital analysis of pupil images was used to determine the Cartesian coordinates (nasal-temporal, horizontal axis, superior-inferior, vertical axis) of the first Purkinje reflection point (approximating the corneal intersection of the visual axis [corneal vertex]) to the pupil geometric center (approximating the corneal intersection of the line of sight [corneal apex]). Pupil size changes were measured, and the correlation between vertex-to-apex shift changes and postoperative pupil centroid shift was evaluated. RESULTS: The study evaluated 40 eyes. The pupil size (diameter) change corresponded to a relative reduction of -9.8% for photopic pupils and -9.1% for mesopic pupils; the difference was statistically significant (P = .045 and P = .011, respectively). Also, there was a reduction in the centroid shift (all eyes) from a mean of 0.12 mm preoperatively to 0.05 mm postoperatively as a result of the postoperative minus temporal horizontal difference between the corneal vertex and the apex. CONCLUSIONS: Cataract extraction surgery appears to affect pupil size and centration. Specifically, a smaller pupil and less temporal shift were recorded. These data may have clinical relevance in targeted intraoperative intraocular lens centration. FINANCIAL DISCLOSURE: Dr. Kanellopoulos is a consultant to Alcon Surgical, Inc., Wavelight Laser Technologie AG, Allergan, Avedro, Inc., and i-Optics Corp. No author has a financial or proprietary interest in any material or method mentioned.