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1.
Clin Exp Ophthalmol ; 52(1): 31-41, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38050340

RESUMO

BACKGROUND: To evaluate the intraindividual visual performance of a spherical and extended depth of field (EDOF) IOL used in a mix-and-match approach. METHODS: Single centre (tertiary care centre), retrospective consecutive case series. Included patients had uneventful cataract surgery with implantation of a spherical monofocal IOL (CT Spheris 204) in the dominant eye and a diffractive EDOF IOL (AT LARA 829) in the non-dominant eye. Monocular and binocular defocus curves and visual acuity at various distances were assessed. In addition, binocular reading speed, contrast sensitivity, and patient satisfaction using QOV, Catquest 9SF, and glare/halo questionnaires are reported. RESULTS: A total of 29 patients (58 eyes) were included. We observed significant intra-individual differences for monocular DCIVA, DCNVA, UIVA, and UNVA. There were no differences in monocular BCDVA or UDVA. The monocular defocus curves for the two IOLs significantly differed at defocus steps between -1.0 and -3.5 D. 93.10% of patients reported they would opt for the same combination of IOLs. CONCLUSION: Excellent uncorrected and corrected distance visual acuity was demonstrated in both groups. The mix-and-match approach described in this study yielded good intermediate vision and improved near vision with high-patient satisfaction.


Assuntos
Lentes Intraoculares , Facoemulsificação , Humanos , Refração Ocular , Implante de Lente Intraocular , Pseudofacia , Estudos Retrospectivos , Visão Binocular , Satisfação do Paciente , Desenho de Prótese
2.
J Mech Behav Biomed Mater ; 147: 106141, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37748318

RESUMO

The number of elective refractive surgeries is constantly increasing due to the drastic increase in myopia prevalence. Since corneal biomechanics are critical to human vision, accurate modeling is essential to improve surgical planning and optimize the results of laser vision correction. In this study, we present a numerical model of the anterior cornea of young patients who are candidates for laser vision correction. Model parameters were determined from uniaxial tests performed on lenticules of patients undergoing refractive surgery by means of lenticule extraction, using patient-specific models of the lenticules. The models also took into account the known orientation of collagen fibers in the tissue, which have an isotropic distribution in the corneal plane, while they are aligned along the corneal curvature and have a low dispersion outside the corneal plane. The model was able to reproduce the experimental data well with only three parameters. These parameters, determined using a realistic fiber distribution, yielded lower values than those reported in the literature. Accurate characterization and modeling of the cornea of young patients is essential to study better refractive surgery for the population undergoing these treatments, to develop in silico models that take corneal biomechanics into account when planning refractive surgery, and to provide a basis for improving visual outcomes in the rapidly growing population undergoing these treatments.


Assuntos
Córnea , Substância Própria , Humanos , Análise de Elementos Finitos , Córnea/cirurgia , Substância Própria/cirurgia
3.
J Cataract Refract Surg ; 49(10): 1025-1035, 2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37532255

RESUMO

PURPOSE: To determine (1) if measurements of surgically induced astigmatism (SIA) as measured by keratometry (K) and total keratometry (TK) differ (2) if SIA affects the magnitude and/or meridian of keratometric astigmatism (3) if SIA evolves over time. SETTING: Tertiary care center. DESIGN: Retrospective data analysis. METHODS: A swept-source optical coherence tomography biometry dataset (IOLMaster700) consisting of 498 eyes (327 patients) from a tertiary care center was analyzed. For all eyes preoperative and postoperative biometric measurements at 1-month, 3-month, and 6-months postoperative visits were considered for vector analysis of SIA K and SIA TK . RESULTS: Centroids in right and left eyes were 0.26 diopters (D) @5 degrees/0.31 D @1 degree for SIA K and 0.27 D @4 degrees/0.34 D @1 degree for SIA TK . Centroids for difference vectors K-TK in right and left eyes were 0.02 D @ 176 degrees/0.03 D @6 degrees. The mean SIA magnitudes in right and left eyes were 0.48 ± 0.41 D and 0.50 ± 0.37 D for SIA K and 0.53 ± 0.42 D and 0.54 ± 0.40 D for SIA TK . In eyes with ATR astigmatism, an increase in postoperative astigmatism magnitude was more common than a decrease. More than 30% of eyes showed changes in the meridian of more than 15 degrees. CONCLUSIONS: Overall, we observed differences in K- and TK-derived SIA, and changes in SIA magnitude over time. For postsurgical interventions, postoperative astigmatism meridian values should be measured to base treatments. Astigmatism magnitude showed a tendency to decrease for steep-meridian incisions and to increase in flat-meridian incisions.


Assuntos
Astigmatismo , Extração de Catarata , Catarata , Facoemulsificação , Humanos , Astigmatismo/diagnóstico , Astigmatismo/etiologia , Astigmatismo/cirurgia , Implante de Lente Intraocular/métodos , Estudos Retrospectivos , Córnea/cirurgia , Topografia da Córnea , Facoemulsificação/métodos
4.
Klin Monbl Augenheilkd ; 240(6): 779-782, 2023 Jun.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-37142238

RESUMO

BACKGROUND: Information about corneal biomechanics is crucial for achieving satisfactory outcomes after surgical corneal interventions, e.g., for astigmatic keratotomies, but also to identify corneas that are at risk for postoperative complications such as corneal ectasia. Hitherto, approaches to characterize corneal biomechanics in an in vivo setting have yielded only minor success, demonstrating the unmet medical need for a diagnostic technique to measure ocular biomechanics. OBJECTIVE: This review shall explain the mechanism of Brillouin spectroscopy and summarize the current scientific knowledge for ocular tissue. METHODS: PubMed research of relevant experimental and clinical publications, as well as reporting of own experience using Brillouin spectroscopy. RESULTS: Brillouin spectroscopy can measure different biomechanical moduli with a high spatial resolution. Currently, available devices are able to detect focal corneal weakening, e.g., in keratoconus, as well as stiffening after corneal cross-linking. Also, the mechanical properties of the crystalline can be measured. Corneal anisotropy and hydration, together with the dependence on the angle of the incident laser beam in Brillouin spectroscopy, are challenges in the precise interpretation of measured data. A clear advantage in the detection of subclinical keratoconus compared to corneal tomography, however, has not been shown yet. CONCLUSION: Brillouin spectroscopy is a technique to characterize biomechanical properties of ocular tissue in vivo. Published results confirm ex vivo data of ocular biomechanics; however, further improvements in the acquisition and interpretation of measured data are required until this technique can be used in a clinically viable setting.


Assuntos
Ceratocone , Oftalmologia , Humanos , Ceratocone/cirurgia , Córnea , Crosslinking Corneano , Análise Espectral/métodos
5.
J Cataract Refract Surg ; 49(6): 649-653, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-37257174

RESUMO

A 51-year-old man was referred for refractive surgery evaluation. Spectacle dependence and poor visual quality in both eyes was his chief complaint. He cannot tolerate contact lenses. Corrected distance visual acuity (CDVA) was 20/40 in both eyes. Manifest refraction was +5.25 -2.25 @ 90 (20/40) in the right eye and +6.25 -2.25 @ 105 (20/40) in the left eye. The patient had a history of radial keratotomy (RK) almost 30 years ago in both eyes and at the slitlamp presented 8 RK incisions, proportionally spaced between one another. All incisions were closed, and there were no relevant signs of scarring. The patient denied any history of ocular trauma, systemic disease, or medications. Corneal topography with different technologies revealed an irregular pattern with marked central flattening in both eyes, with some points below 30 diopters (D) (Supplemental Figures 1 and 2, available at http://links.lww.com/JRS/A862 and http://links.lww.com/JRS/A863, respectively). There were no signs of cataract, and fundus examination was normal. Optical coherence tomography (OCT) of the right eye revealed a more homogeneous thickness pattern, little variation between the thinnest and thickest areas, and adequate transparency (Figure 1JOURNAL/jcrs/04.03/02158034-202306000-00018/figure1/v/2023-05-31T172126Z/r/image-tiff). In the left eye, there is wide variability between the thinnest and thickest stromal points, with annular thinning and central thickening (Figure 2JOURNAL/jcrs/04.03/02158034-202306000-00018/figure2/v/2023-05-31T172126Z/r/image-tiff). Both eyes show marked epithelial irregularity. Considering this patient's current ocular status, how would you reach visual rehabilitation? Because he is contact lens intolerant, would you consider surface ablation, for example, photorefractive keratectomy (PRK) with mitomycin-C (MMC)? If that were the case, would you think of an optimized or a topography-guided (TG) treatment? Would you immediately consider a corneal transplant option? Would you instead consider a more conservative approach? Which one and why?


Assuntos
Anormalidades do Olho , Hiperopia , Ceratotomia Radial , Ceratectomia Fotorrefrativa , Masculino , Humanos , Pessoa de Meia-Idade , Ceratotomia Radial/efeitos adversos , Hiperopia/cirurgia , Hiperopia/etiologia , Lasers de Excimer/uso terapêutico , Ceratectomia Fotorrefrativa/métodos , Anormalidades do Olho/cirurgia , Córnea/cirurgia , Refração Ocular
6.
J Cataract Refract Surg ; 49(8): 795-803, 2023 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-37097284

RESUMO

PURPOSE: To evaluate the accuracy of various variations of new-generation multivariate intraocular lens (IOL) power calculation using the Barrett Universal II, Castrop, Emmetropia Verifying Optical 2.0, Hill-Radial Basis Function 3.0, Kane, and PEARL-DGS formulas with and without optional biometric parameters. SETTING: Tertiary care academic medical center. DESIGN: Retrospective case series. Single-center study. METHODS: Inclusion of patients after uneventful cataract surgery implanting AU00T0 IOLs. Data from one eye per patient were randomly included. Eyes with a corrected distance visual acuity worse than 0.1 logMAR were excluded. IOLCON-optimized constants were used for all formulas other than the Castrop formula. The outcome measures were prediction error (PE) and absolute prediction error (absPE) for the 6 study formulas. RESULTS: 251 eyes from 251 patients were assessed. Excluding lens thickness led to statistically significant differences in absPE in several formulas. Leaving out horizontal corneal diameter did not impact absPE in several formulas. Differences in PE offset were observed between the various formula variations. CONCLUSIONS: When using multivariate formulas with an A-constant, including certain optional parameters is vital for optimal refractive results. Formula variations excluding certain biometric parameters need specifically optimized constants and do not perform similarly when using the constant of the respective formula using all parameters.


Assuntos
Extração de Catarata , Lentes Intraoculares , Facoemulsificação , Humanos , Estudos Retrospectivos , Refração Ocular , Acuidade Visual , Extração de Catarata/métodos , Biometria/métodos , Óptica e Fotônica , Comprimento Axial do Olho
7.
Klin Monbl Augenheilkd ; 240(2): 158-162, 2023 Feb.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-36634688

RESUMO

BACKGROUND: In recent years, an increasing number of surgical microscopes fitted with an OCT module (intraoperative OCT, iOCT) have become available, providing high-resolution images of the surgical site in real time. While a 2018 survey at our hospital showed that iOCT delivered an additional intraoperative benefit in only 2.4% of all operations, considering that the manufacturer had since revised the hardware and software, we conducted a second user evaluation of this technology. MATERIAL AND METHODS: Prospective monocentric analysis of the application and user-friendliness of an EnFocus Ultra-Deep OCT (Leica Microsystems) over a period of 25 (2018) and 20 working days (2021). A standardized questionnaire was used to assess the surgeons' use of iOCT and its influence on the surgical course. RESULTS: 118 operations were performed over a 25-day period in 2018 and 92 operations were performed over a 20-day period in 2021. In 2018, iOCT was used in 24.6% and in 2021 in 48.9% of all surgeries, with iOCT proving to be "critical" to the surgical course in 2.4% and 3.3% of cases, respectively, as assessed by the surgeons in both years. These were operations in which the intraocular view was limited, e.g., with decompensated cornea, vitreous hemorrhage, or after previous surgery, e.g., after penetrating keratoplasty. CONCLUSION: Further development of the user interface led to an improvement in usability, and the iOCT was used significantly more often. In both years, the iOCT proved to be critical for the course of the surgery in a comparably small number of operations, especially those involving complex situations.


Assuntos
Córnea , Tomografia de Coerência Óptica , Humanos , Tomografia de Coerência Óptica/métodos , Estudos Prospectivos , Ceratoplastia Penetrante , Microscopia
8.
Arq Bras Oftalmol ; 86(5): e20230059, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35544929

RESUMO

We report a case of acute corneal hydrops followed by corneal perforation five years after corneal cross-linking for keratoconus. A healthy 24-year-old female patient underwent Dresden protocol cross-linking in her left eye due to advanced keratoconus. After five years of a stable cornea, she returned with epiphora, blurred vision, and a soft left eye. Acute hydrops and corneal perforation were diagnosed. There was no history of pregnancy, atopy, eye rubbing, trauma, or contact lens use. Local antibiotic and eye patching were applied. Three months after the resolution of the acute episode, she retained useful visual acuity with no need for further surgery. Although cross-linking efficiently halts keratoconus, progression can occur, leading to corneal hydrops and perforation, even in the absence of any risk factors.


Assuntos
Edema da Córnea , Perfuração da Córnea , Ceratocone , Humanos , Feminino , Adulto Jovem , Adulto , Ceratocone/complicações , Ceratocone/tratamento farmacológico , Ceratocone/cirurgia , Perfuração da Córnea/etiologia , Crosslinking Corneano , Edema/complicações , Edema da Córnea/etiologia , Topografia da Córnea
9.
Curr Eye Res ; 48(2): 144-151, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36458595

RESUMO

PURPOSE: Corneal Crosslinking (CXL) strengthens the keratoconus cornea and prevents further disease progression. Modified crosslinking protocols and different riboflavin solutions have been proposed to optimize the procedure and improve treatment success. METHODS: PubMed research of relevant publications and report of own experiences with different CXL protocols. RESULTS: Accelerated CXL shows comparable efficiency with shorter surgery time and similar complication rates. Customized CXL provides improved results with faster epithelial healing. CXL in a hyperoxic environment seems to be a safe and effective transepithelial alternative with presumably less complications and fewer side effects. Thin corneas (<400 µm) can be treated safely by corneal swelling using hypoosmolar riboflavin solutions and reducing the applied UV-energy. The combination of CXL with photorefractive keratectomy (PRK) can be considered in patients with contact lens intolerance improving visual acuity, however, with increased risk of visual loss compared to CXL alone. Two-Photon (2Ph) CXL is a promising new technology enabling three-dimensional CXL. DISCUSSION: Recently developed CXL protocols offer advantages over the standard "Dresden-protocol" and should be considered in patients with progressive keratectasia.


Assuntos
Ceratocone , Fotoquimioterapia , Humanos , Fármacos Fotossensibilizantes/uso terapêutico , Fotoquimioterapia/métodos , Refração Ocular , Topografia da Córnea , Córnea/cirurgia , Riboflavina/uso terapêutico , Ceratocone/tratamento farmacológico , Reagentes de Ligações Cruzadas/farmacologia , Reagentes de Ligações Cruzadas/uso terapêutico , Raios Ultravioleta
10.
Arq. bras. oftalmol ; 86(5): e20230059, 2023. graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1513682

RESUMO

ABSTRACT We report a case of acute corneal hydrops followed by corneal perforation five years after corneal cross-linking for keratoconus. A healthy 24-year-old female patient underwent Dresden protocol cross-linking in her left eye due to advanced keratoconus. After five years of a stable cornea, she returned with epiphora, blurred vision, and a soft left eye. Acute hydrops and corneal perforation were diagnosed. There was no history of pregnancy, atopy, eye rubbing, trauma, or contact lens use. Local antibiotic and eye patching were applied. Three months after the resolution of the acute episode, she retained useful visual acuity with no need for further surgery. Although cross-linking efficiently halts keratoconus, progression can occur, leading to corneal hydrops and perforation, even in the absence of any risk factors.


RESUMO Este é o relato de um caso de hidropisia aguda seguida de perfuração corneana cinco anos após reticulação corneana para ceratocone. Uma paciente saudável de 24 anos foi submetida a reticulação corneana no olho esquerdo pelo protocolo de Dresden, devido a um ceratocone avançado. Após cinco anos com a córnea estável, a paciente retornou com epífora, visão turva e amolecimento do olho esquerdo. Foram diagnosticadas hidropisia aguda e perfuração corneana. A paciente não tinha história de gravidez, atopia, fricção ocular, trauma ou uso de lentes de contato. Foram aplicados um antibiótico local e um tampão oftalmológico. Três meses após a resolução do episódio agudo, ela manteve uma acuidade visual útil, sem necessidade de novas cirurgias. Embora a reticulação interrompa de forma eficiente o ceratocone, pode ocorrer progressão, levando a hidropisia e perfuração da córnea, mesmo na ausência de fatores de risco.

11.
J Refract Surg ; 38(9): 618, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36098389
12.
Klin Monbl Augenheilkd ; 239(8): 971-981, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35973684

RESUMO

BACKGROUND: An intraocular lens (IOL) calculation in eyes that have undergone laser vision correction (LVC) poses a significant clinical issue in regards to both patient expectation and accuracy. This review aims to describe the pitfalls of IOL power calculation after LVC and give an overview of the current methods of IOL power calculation after LVC. REVIEW: Problems after LVC derive from the measurement of anterior corneal radii, central corneal thickness, asphericity, and the predicted effective lens position. A central issue is that most conventional 3rd generation formulas estimate lens position amongst other parameters on keratometry, which is altered in post-LVC eyes. CONCLUSION: An IOL power calculation results in eyes with prior LVC that are notably impaired in eyes without prior surgery. Effective corneal power including anterior corneal curvature, posterior corneal curvature, CCT (central corneal thickness), and asphericity is essential. Total keratometry in combination with the Barrett True-K, EVO (emmetropia verifiying optical formula), or Haigis formula is relatively uncomplicated and seems to provide good results, as does the Barrett True-K formula with anterior K values. The ASCRS ( American Society of Cataract and Refractive Surgery) calculator combines results of various formulae and averages results, which allows a direct comparison between the different methods. Tomography-based raytracing and the Kane and the Castrop formulae need to be evaluated by future studies.


Assuntos
Lentes Intraoculares , Facoemulsificação , Biometria , Humanos , Lasers , Implante de Lente Intraocular , Óptica e Fotônica , Facoemulsificação/métodos , Refração Ocular , Estudos Retrospectivos
13.
J Refract Surg ; 38(4): 250-255, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35412926

RESUMO

PURPOSE: To detect keratoconus progression, accuracy of tomographic measurements is crucial. The impoved axial resolution of optical coherence tomography (OCT) compared to Scheimpflug photography serves as the motivation to investigate and compare the repeatability of the anterior segment OCT MS-39 (CSO) to Pentacam HR (Oculus Optikgeräte GmbH) in patients with keratoconus. METHODS: One hundred twenty-three eyes of 123 patients with keratoconus were enrolled and subdivided in four groups by maximum keratometry (Kmax): Kmax < 48.00 diopters (D), Kmax of 48.00 to 53.01 D, Kmax of 53.00 to 58.00 D, and Kmax > 58.00 D. Three consecutive measurements per eye were acquired with the MS-39 and compared to the Pentacam HR. Kmax, thinnest pachymetry, anterior asphericity, and posterior elevation data were compared. Within-subject standard deviation (Sw), coefficient of variation (CoV), test-retest repeatability (TRT), and the intra-class correlation (ICC) were calculated and evaluated. Bland-Altman plots were also analyzed. RESULTS: The Pentacam HR measures significantly higher Kmax values than the MS-39, with a more pronounced difference for severe cases of keratoconus (0.57 D for all cases; 1.88 D for cases with Kmax > 58.00 D). Thinnest pachymetry was approximately 5 µm thinner when measured by the Pentacam HR than the MS-39, independently of keratoconus stage. A further progressed keratoconus stage was significantly associated with increased measurement errors and resulted in worse repeatability (Kmax < 48.00 D: Sw = 0.18 D, TRT = 0.50 D, CoV = 0.39%, ICC = 0.989; Kmax > 58.00 D: Sw = 0.53 D, TRT = 1.48 D, CoV = 0.90%, ICC = 0.984). The behavior was similar for other tomographic parameters. CONCLUSIONS: The Pentacam HR and the MS-39 have an overall good agreement for keratoconus; however, the Pentacam HR measures steeper and thinner than the MS-39. The association between the magnitude of topographic and tomographic parameters and their measurement errors suggests that the diagnosis of keratoconus disease progression should be based on the stage and the test-retest repeatability rather than on a fixed value (eg, 1.00 D). [J Refract Surg. 2022;38(4):250-255.].


Assuntos
Ceratocone/patologia , Tomografia de Coerência Óptica , Córnea/patologia , Paquimetria Corneana , Topografia da Córnea , Progressão da Doença , Humanos , Hiperplasia/patologia , Ceratocone/diagnóstico , Estudos Prospectivos , Reprodutibilidade dos Testes
14.
Ophthalmologe ; 119(4): 350-357, 2022 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-35147774

RESUMO

BACKGROUND: Corneal crosslinking (CXL) is used in keratoconus to strengthen and stabilize the cornea and to prevent further progression with subsequent visual loss and the possible need for keratoplasty. Correct treatment indications is crucial in this context. Since the introduction of the initial Dresden protocol, other modified CXL protocols have been proposed to optimize treatment success. OBJECTIVE: The relevant parameters for treatment indications are explained and the clinical results of new CXL protocols are presented. METHODS: The currently valid criteria with respect to the indications for CXL in keratoconus, PubMed search for relevant publications and own experiences with different CXL protocols are presented. RESULTS: The reproducibility of topographic parameters depends on the stage of the keratoconus. Accelerated CXL as well as transepithelial CXL with a hyperoxic environment show comparable efficiency with shorter surgery time and possibly lower complication rates. Customized CXL with an individualized UV irradiation profile provides improved results with faster epithelial healing. Lower UV energy doses enable CXL to be conducted in eyes with minimal stromal pachymetry of less than 400 µm before irradiation. The combination of CXL with photorefractive keratectomy (PRK) provides visual acuity improvements but also increases the risk of visual loss. CONCLUSION: Current indication rules for CXL neglect the reduced reproducability of topographic and tomographic measurements in keratoconus. The latest CXL protocols presented here provide a safe alternative with similar and/or better efficacy compared to standard CXL. The combination of CXL with PRK offers an option for visual rehabilitation in patients with contact lens intolerance.


Assuntos
Ceratocone , Fotoquimioterapia , Colágeno , Córnea/cirurgia , Topografia da Córnea , Reagentes de Ligações Cruzadas , Humanos , Ceratocone/diagnóstico , Ceratocone/tratamento farmacológico , Ceratocone/cirurgia , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/uso terapêutico , Reprodutibilidade dos Testes , Riboflavina/uso terapêutico , Raios Ultravioleta
15.
Exp Eye Res ; 213: 108842, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34793829

RESUMO

Avoiding damage of the endothelial cells, especially in thin corneas, remains a challenge in corneal collagen crosslinking (CXL). Knowledge of the riboflavin gradients and the UV absorption characteristics after topical application of riboflavin in concentrations ranging from 0.1% to 0.5% could optimize the treatment. In this study, we present a model to calculate the UV-intensity depending on the corneal thickness. Ten groups of de-epithelialized porcine corneas were divided into 2 subgroups. Five groups received an imbibition of 10 min and the other five groups for 30 min. The applied riboflavin concentrations were 0.1%, 0.2%, 0.3%, 0.4% and 0.5% diluted in a 15% dextran solution for each subgroup. After the imbibition process, two-photon fluorescence microscopy was used to determine fluorescence intensity, which was compared to samples after saturation, yielding the absolute riboflavin concentration gradient of the cornea. The extinction coefficient of riboflavin solutions was measured using a spectrophotometer. Combining the obtained riboflavin concentrations and the extinction coefficients, a depth-dependent UV-intensity profile was calculated for each group. With increasing corneal depth, the riboflavin concentration decreased for all imbibition solutions and application times. The diffusion coefficients of 10 min imbibition time were higher than for 30 min. A higher RF concentration and a longer imbibition time resulted in higher UV-absorption and a lower UV-intensity in the depth of the cornea. Calculated UV-transmission was 6 percentage points lower compared to the measured transmission. By increasing the riboflavin concentration of the imbibition solution, a substantially higher UV-absorption inside the cornea is achieved. This offers a simple treatment option to control the depth of crosslinking e.g. in thin corneas, resulting in a lower risk of endothelial damage.


Assuntos
Absorção de Radiação/efeitos dos fármacos , Substância Própria/metabolismo , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Raios Ultravioleta , Administração Oftálmica , Animais , Paquimetria Corneana , Substância Própria/efeitos da radiação , Reagentes de Ligações Cruzadas , Microscopia de Fluorescência por Excitação Multifotônica , Soluções Oftálmicas , Fotoquimioterapia , Fármacos Fotossensibilizantes/administração & dosagem , Riboflavina/administração & dosagem , Suínos
16.
J Refract Surg ; 37(9): 631-635, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34506235

RESUMO

PURPOSE: To evaluate corneal stiffening in porcine eyes induced by corneal cross-linking (CXL) using riboflavin dissolved in either aqueous dextran or hydroxypropyl methylcellulose (HPMC) solution. METHODS: Fifty-one porcine corneas were divided into three groups of 17 each. After deepithelialization, the first (Dresden) group was treated for 30 minutes with 0.1% riboflavin (riboflavin-5-monophosphate in 0.9% NaCl) dissolved in hypertonic 20% dextran and the second (HPMC) group for 30 minutes with isotonic solution containing 0.1% riboflavin and 1.1% HPMC. Thereafter, corneas of both groups were irradiated using 5.4 J/cm2 (irradiance of 9 mW/cm2 for 10 minutes; 10*9). After CXL, all corneas were kept in an isotonic 16% dextran bath for 2 hours to obtain an equal hydration state. The third group served as the control group. Stress-strain measurements were performed on 5-mm-wide strips. Corneal thickness was monitored throughout the entire course of the experiments. RESULTS: The required stress for a 10% strain was increased by 83% in the Dresden group and 35% in the HPMC group compared to the control group. Resultant Young's modulus (at 10% strain) was 2.53 ± 0.73, 1.87 ± 0.50, and 1.47 ± 0.44 Pa for the Dresden, HPMC, and control groups, respectively. The differences between the Dresden and HPMC groups (P = .006), the Dresden and control groups (P < .001), and the HPMC and control groups (P = .014) were statistically significant. Pachymetry measurements showed a significantly increased corneal thickness after application of HPMC compared with the Dresden group (P = .002) and control group (P = .041). CONCLUSIONS: The biomechanical stiffening of the cornea by CXL can be achieved using dextran- and HPMC-based riboflavin solutions in porcine corneas with an application time of 30 minutes. Dextran-based riboflavin solutions seem to induce a slightly stronger biomechanical response in this setting. HPMC solutions induce less thinning than dextran solutions. [J Refract Surg. 2021;37(9):631-635.].


Assuntos
Substância Própria , Dextranos , Animais , Fenômenos Biomecânicos , Colágeno , Córnea , Reagentes de Ligações Cruzadas , Derivados da Hipromelose , Fármacos Fotossensibilizantes , Riboflavina/farmacologia , Suínos , Raios Ultravioleta
20.
J Refract Surg ; 35(6): 346-352, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31185099

RESUMO

PURPOSE: To evaluate a substantially improved wavefront acquisition technique (Peramis; SCHWIND eye-tech-solutions, Kleinostheim, Germany) for selective wavefront-guided aberration correction to improve satisfaction after implantation of trifocal intraocular lenses (IOLs). METHODS: Of 213 eyes from 108 consecutive patients receiving cataract surgery with multifocal IOL implantation (FineVision; PhysIOL, Liége, Belgium), 56 eyes (26%) of 42 dissatisfied patients were treated with selective wavefront-guided laser in situ keratomileusis (LASIK) (Amaris 1050; SCHWIND eye-tech-solutions) free of cost with a follow-up of 12 months. Selective wavefront-guided ablation corrected for all aberrations except spherical aberrations to preserve the apodization and therefore to enhance the multifocal effect. The degree of satisfaction after trifocal IOL implantation, its increase after selective wavefront-guided LASIK, and the refractive error (spherical equivalent, refractive astigmatism) before and after selective wavefront-guided LASIK were evaluated. RESULTS: Refractive astigmatism of greater than 0.50 diopters (D) was the most frequent residual refractive error (63%), followed by myopia (45%), hyperopia (20%), and increased ocular higher order aberrations (13%). After selective wavefront-guided LASIK, the refractive target (±0.50 D) was achieved in 98% and refractive astigmatism was 0.50 D or less in 93% of the eyes operated on. The overall satisfaction score in dissatisfied patients increased from 2.1 ± 0.8 preoperatively to 3.6 ± 0.8 (out of 4). Eighty-eight percent of initially dissatisfied patients would choose this procedure again. CONCLUSIONS: Selective wavefront-guided LASIK reduced refractive errors and significantly increased spectacle independence and satisfaction, which may lead to a better acceptance of trifocal IOLs. [J Refract Surg. 2019;35(6):346-352.].


Assuntos
Ceratomileuse Assistida por Excimer Laser In Situ/métodos , Lentes Intraoculares Multifocais/efeitos adversos , Satisfação do Paciente , Facoemulsificação/efeitos adversos , Erros de Refração/etiologia , Erros de Refração/terapia , Aberrometria , Adulto , Idoso , Idoso de 80 Anos ou mais , Topografia da Córnea , Feminino , Humanos , Lasers de Excimer/uso terapêutico , Implante de Lente Intraocular , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Inquéritos e Questionários , Resultado do Tratamento , Acuidade Visual/fisiologia
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