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Papers by Cristina Peris

Journal of Cataract & Refractive Surgery, 2004

Purpose: To evaluate the feasibility and safety of using phakic intraocular lenses (IOLs) to corr... more Purpose: To evaluate the feasibility and safety of using phakic intraocular lenses (IOLs) to correct high myopia by comparing 3 IOL models: Adatomed, Staar, and Artisan.

Biomecánica y arquitectura corneal, 2014

Biomecánica y arquitectura corneal, 2014

Biomecánica y arquitectura corneal, 2014

Acta Ophthalmologica Scandinavica, 2007

Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocul... more Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocular lenses (IOL) is analyzed in vitro. Following the EN-ISO international standard, the IOLs’ modulation transfer functions (MTF) are determined for both distance and near vision. The behaviour of these curves when the pupil size varies is studied.Methods: The IOLs analyzed were: AcrySoft ResTor SN60D3 (Alcon) and Tecnis ZM900 (AMO). The MTF was calculated from the cross line-spread function recorded with the OPAL Vector System (Image Science Ltd. Oxford) by using fast Fourier transform techniques. The artificial eye model used simulates in vivo conditions of the anterior chamber including an artificial cornea and a physiological solution where the IOL were positioned. Following pupil sizes were analyzed: 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 mm.Results: The MTFs of the two multifocal IOLs analyzed show a good image quality for both in all conditions analyzed. However, a monofocal IOL with the same power (22.5 dioptres) provides a better image quality for distance vision. The Strehl ratio of the two multifocal IOLs decreases when pupil size increases, for both distance and near vision. To the contrary, the average modulation (from 0 to 100 c/mm) of the two multifocal IOLs remains approximately constant for all the pupil sizes.Conclusions: The image quality provided by the two multifocal refractive-diffractive IOLs is very similar, although the quality with ResTor IOL is always slightly better than with Tecnis IOL in distance vision. In near vision, to the contrary. The conclusion is that when the distance vision improves the near vision worsens and vice-versa.

Ophthalmic Plastic and Reconstructive Surgery, 2008

ABSTRACT Aspergillus niger infection of an exenterated orbit is a very rare occurrence. Treatment... more ABSTRACT Aspergillus niger infection of an exenterated orbit is a very rare occurrence. Treatment includes extensive surgical debridement with socket lavage with 0.6% hydrogen peroxide, oral itraconazole, and local amphotericin B. We describe a case of A. niger infection in an exenterated orbit, unresponsive to local amphotericin B, that was successfully treated with weekly boric acid irrigation. We conclude that local and conservative therapy with 2.5% boric acid solution in 70% ethanol is a useful option in the management of these cases.

Acta Ophthalmologica, 2008

Purpose To describe the histopathologic changes in human ectasic corneas, induced after implantat... more Purpose To describe the histopathologic changes in human ectasic corneas, induced after implantation of intracorneal ring segments.Methods Ten eyes (7 advanced keratoconus, 2 post-lasik ectasia and 1 marginal pellucid degeneration) recieved corneal implants (Ferrara-Keraring like) for treatment. Due to a poor refractive out-come they had penetrating keratoplasty.Results Conventional histology on all specimens after hematein-eosin stain, showed no inflammation signs and hypoplasia of the corneal epithelium immediately surrounding the channel.Conclusion Histopathologic changes seem to be complety reversible after implant removal. Longer follow-up is necessary to determine whether they accelerate corneal thinning or inflammation response.

Journal of Cataract and Refractive Surgery, 2009

To determine whether the difference in optic quality between 2 types of phakic intraocular lenses... more To determine whether the difference in optic quality between 2 types of phakic intraocular lenses (pIOLs) affects visual quality. SETTING: Fundación Oftalmológica del Mediterráneo, Valencia, Spain.

Acta Ophthalmologica, 2008

Purpose To establish the possible beneficial effects of three synthetic antioxidants: S-adenosil-... more Purpose To establish the possible beneficial effects of three synthetic antioxidants: S-adenosil-L-methionine (SAMe), N-acetyl-L-cysteine (NAC) and Ebselen in optic nerve damage following chronic ethanol feeding in adult rats.Methods Twenty male Sprague-Dawley rats (five groups of four animals each) were fed a liquid, ethanol-containing diet with littermates given isocaloric amounts of ethanol-free diet serving as controls. Antioxidants were administered by dissolving them in the liquid diet at 0.4 mg/ml (SAMe), 0.163 mg/ml (NAC) and 5.33 mg/ml (Ebselen). After 6 weeks, optic nerves were obtained and parameters that are relevant for the modulation of oxidative stress, such as antioxidants -GSH content and Glutathione-peroxidase (GSH-Px) activity- and lipid peroxidation-derived end products -malondialdehyde (MDA)- were determined. Comparisons between groups were done using Student´s t-test for grouped data and one-way ANOVA. Differences were considered significant at p<0.05.Results N-acetyl-L-cysteine and Ebselen were able to normalise MDA content and to restore GSH content and GSH-peroxidase activity, to values not significantly different from those of controls (p>0.05). Treatment with SAMe slightly improved values of some parameters, although no statistically beneficial (p<0.05 versus control).Conclusion These results support the use of NAC and Ebselen for the treatment of chronic alcohol-induced optic nerve damage.

Acta Ophthalmologica Scandinavica, 2007

Purpose: To analyze the standard methods used to describe intraocular lenses (IOL) and to suggest... more Purpose: To analyze the standard methods used to describe intraocular lenses (IOL) and to suggest some improvements to make them applicable for multifocal IOLs.Methods: The EN-ISO standards and the standards of the American National Standards Institute (ANSI) for the evaluation of the performance of IOLs are tested for multifocal IOLs. The MTF of the one refractive multifocal IOL and two hybrid refractive-diffractive multifocal IOLs is measured for both distance focus and near focus and using different pupil sizes.Results: The average modulation (AM) from 0 to 100 c/mm of multifocal IOLs (for the distance focus) is about 40-50% lower than the AM of monofocal IOLs, for all pupil sizes studied. This fact suggests that the EN ISO standards must be revised in some points to be adapted for multifocal IOLs. Moreover, the near focus of the refractive IOL only appears beyond 3.5 mm of pupil size; in consequence this type of multifocal IOL could not be described only with a 3 mm pupil as stated in ISO standard.The width at half height of the point spread function (PSF) or the cut-off frequency value of the MTF, are not useful for multifocal IOLs. Multifocal IOLs can have a narrow PSF at half height but be very wide at the bottom, occuring this even in some so-called apodized IOLs. The cut-off frequency value is also useful in monofocal lenses as quality factor to compare MTFs of different lenses or pupil sizes because an approximately uniform slope for the MTF is suppose.Conclusions: EN-ISO and ANSI, demand the modulation of only one pupil and one frequency: 3 mm and 100 c/mm. We recommend to measure at least with 2 different pupils and to give the AM value for both distance and near focus.

Acta Ophthalmologica, 2008

Purpose Corneal hysteresis is a viscoelastic property characterized by the difference in behavior... more Purpose Corneal hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis in different eyes: healthy eyes, keratoconic eyes and keratoconic eyes after intracorneal ring implants.Methods This study comprised 95 eyes of 59 patients. The study population was divided into 3 groups. We analyze 30 healthy human eyes, 35 keratoconic eyes (Amsler grade II-III) and 30 keratoconic eyes after intracorneal rings implantation. Corneal biomechanical properties of these eyes were measured with the Ocular Response Analyser (ORA-Reichert) according to two parameters: corneal hysteresis (CH) and corneal resistance factor (CRF. The unpaired T student test was used for statistical analysis.Results Mean CH and CRF in normal eyes (10.78 ± 1.6 (SD) mm Hg, 11.91 mm Hg ± 1.2) was clearly superior than in keratoconus group (8.01 ± 1.5 mm Hg, 7.32 ±1.8 mm Hg). However the difference of these parameters between keratoconus group without intracorneal rings and after corneal ring implantation (7.27mm Hg, 6.32 mm Hg) was not statistically significant (p ≤ 0.01). Mean follow-up period was of one year.Conclusion Corneal hysteresis and CRF values were significantly lower in keratoconic eyes than in normal eyes. But there is no marked differences if we compare these two biomechanical parameters in keratoconic corneas, before and after corneal ring implants. Improvements in the software accuracy of the ORA devices are needed to characterize corneal biomechanics.

Chapters by Cristina Peris

Cabanás M, Alfonso JF, del-Buey MA, Peris C, Bilbao R, González F, Ortega-Usobiaga J, Llovet F. Protocolo de manejo de la ectasia corneal. In: Llovet F, Ortega-Usobiaga J. Cirugía Refractiva: Protocolos. Madrid: SEO; 2014; chapter 20: 227-230., Sep 1, 2014

Journal of Cataract & Refractive Surgery, 2004

Purpose: To evaluate the feasibility and safety of using phakic intraocular lenses (IOLs) to corr... more Purpose: To evaluate the feasibility and safety of using phakic intraocular lenses (IOLs) to correct high myopia by comparing 3 IOL models: Adatomed, Staar, and Artisan.

Biomecánica y arquitectura corneal, 2014

Biomecánica y arquitectura corneal, 2014

Biomecánica y arquitectura corneal, 2014

Acta Ophthalmologica Scandinavica, 2007

Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocul... more Purpose: The optical quality of two types of multifocal, hybrid refractive-diffractive, intraocular lenses (IOL) is analyzed in vitro. Following the EN-ISO international standard, the IOLs’ modulation transfer functions (MTF) are determined for both distance and near vision. The behaviour of these curves when the pupil size varies is studied.Methods: The IOLs analyzed were: AcrySoft ResTor SN60D3 (Alcon) and Tecnis ZM900 (AMO). The MTF was calculated from the cross line-spread function recorded with the OPAL Vector System (Image Science Ltd. Oxford) by using fast Fourier transform techniques. The artificial eye model used simulates in vivo conditions of the anterior chamber including an artificial cornea and a physiological solution where the IOL were positioned. Following pupil sizes were analyzed: 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 mm.Results: The MTFs of the two multifocal IOLs analyzed show a good image quality for both in all conditions analyzed. However, a monofocal IOL with the same power (22.5 dioptres) provides a better image quality for distance vision. The Strehl ratio of the two multifocal IOLs decreases when pupil size increases, for both distance and near vision. To the contrary, the average modulation (from 0 to 100 c/mm) of the two multifocal IOLs remains approximately constant for all the pupil sizes.Conclusions: The image quality provided by the two multifocal refractive-diffractive IOLs is very similar, although the quality with ResTor IOL is always slightly better than with Tecnis IOL in distance vision. In near vision, to the contrary. The conclusion is that when the distance vision improves the near vision worsens and vice-versa.

Ophthalmic Plastic and Reconstructive Surgery, 2008

ABSTRACT Aspergillus niger infection of an exenterated orbit is a very rare occurrence. Treatment... more ABSTRACT Aspergillus niger infection of an exenterated orbit is a very rare occurrence. Treatment includes extensive surgical debridement with socket lavage with 0.6% hydrogen peroxide, oral itraconazole, and local amphotericin B. We describe a case of A. niger infection in an exenterated orbit, unresponsive to local amphotericin B, that was successfully treated with weekly boric acid irrigation. We conclude that local and conservative therapy with 2.5% boric acid solution in 70% ethanol is a useful option in the management of these cases.

Acta Ophthalmologica, 2008

Purpose To describe the histopathologic changes in human ectasic corneas, induced after implantat... more Purpose To describe the histopathologic changes in human ectasic corneas, induced after implantation of intracorneal ring segments.Methods Ten eyes (7 advanced keratoconus, 2 post-lasik ectasia and 1 marginal pellucid degeneration) recieved corneal implants (Ferrara-Keraring like) for treatment. Due to a poor refractive out-come they had penetrating keratoplasty.Results Conventional histology on all specimens after hematein-eosin stain, showed no inflammation signs and hypoplasia of the corneal epithelium immediately surrounding the channel.Conclusion Histopathologic changes seem to be complety reversible after implant removal. Longer follow-up is necessary to determine whether they accelerate corneal thinning or inflammation response.

Journal of Cataract and Refractive Surgery, 2009

To determine whether the difference in optic quality between 2 types of phakic intraocular lenses... more To determine whether the difference in optic quality between 2 types of phakic intraocular lenses (pIOLs) affects visual quality. SETTING: Fundación Oftalmológica del Mediterráneo, Valencia, Spain.

Acta Ophthalmologica, 2008

Purpose To establish the possible beneficial effects of three synthetic antioxidants: S-adenosil-... more Purpose To establish the possible beneficial effects of three synthetic antioxidants: S-adenosil-L-methionine (SAMe), N-acetyl-L-cysteine (NAC) and Ebselen in optic nerve damage following chronic ethanol feeding in adult rats.Methods Twenty male Sprague-Dawley rats (five groups of four animals each) were fed a liquid, ethanol-containing diet with littermates given isocaloric amounts of ethanol-free diet serving as controls. Antioxidants were administered by dissolving them in the liquid diet at 0.4 mg/ml (SAMe), 0.163 mg/ml (NAC) and 5.33 mg/ml (Ebselen). After 6 weeks, optic nerves were obtained and parameters that are relevant for the modulation of oxidative stress, such as antioxidants -GSH content and Glutathione-peroxidase (GSH-Px) activity- and lipid peroxidation-derived end products -malondialdehyde (MDA)- were determined. Comparisons between groups were done using Student´s t-test for grouped data and one-way ANOVA. Differences were considered significant at p<0.05.Results N-acetyl-L-cysteine and Ebselen were able to normalise MDA content and to restore GSH content and GSH-peroxidase activity, to values not significantly different from those of controls (p>0.05). Treatment with SAMe slightly improved values of some parameters, although no statistically beneficial (p<0.05 versus control).Conclusion These results support the use of NAC and Ebselen for the treatment of chronic alcohol-induced optic nerve damage.

Acta Ophthalmologica Scandinavica, 2007

Purpose: To analyze the standard methods used to describe intraocular lenses (IOL) and to suggest... more Purpose: To analyze the standard methods used to describe intraocular lenses (IOL) and to suggest some improvements to make them applicable for multifocal IOLs.Methods: The EN-ISO standards and the standards of the American National Standards Institute (ANSI) for the evaluation of the performance of IOLs are tested for multifocal IOLs. The MTF of the one refractive multifocal IOL and two hybrid refractive-diffractive multifocal IOLs is measured for both distance focus and near focus and using different pupil sizes.Results: The average modulation (AM) from 0 to 100 c/mm of multifocal IOLs (for the distance focus) is about 40-50% lower than the AM of monofocal IOLs, for all pupil sizes studied. This fact suggests that the EN ISO standards must be revised in some points to be adapted for multifocal IOLs. Moreover, the near focus of the refractive IOL only appears beyond 3.5 mm of pupil size; in consequence this type of multifocal IOL could not be described only with a 3 mm pupil as stated in ISO standard.The width at half height of the point spread function (PSF) or the cut-off frequency value of the MTF, are not useful for multifocal IOLs. Multifocal IOLs can have a narrow PSF at half height but be very wide at the bottom, occuring this even in some so-called apodized IOLs. The cut-off frequency value is also useful in monofocal lenses as quality factor to compare MTFs of different lenses or pupil sizes because an approximately uniform slope for the MTF is suppose.Conclusions: EN-ISO and ANSI, demand the modulation of only one pupil and one frequency: 3 mm and 100 c/mm. We recommend to measure at least with 2 different pupils and to give the AM value for both distance and near focus.

Acta Ophthalmologica, 2008

Purpose Corneal hysteresis is a viscoelastic property characterized by the difference in behavior... more Purpose Corneal hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis in different eyes: healthy eyes, keratoconic eyes and keratoconic eyes after intracorneal ring implants.Methods This study comprised 95 eyes of 59 patients. The study population was divided into 3 groups. We analyze 30 healthy human eyes, 35 keratoconic eyes (Amsler grade II-III) and 30 keratoconic eyes after intracorneal rings implantation. Corneal biomechanical properties of these eyes were measured with the Ocular Response Analyser (ORA-Reichert) according to two parameters: corneal hysteresis (CH) and corneal resistance factor (CRF. The unpaired T student test was used for statistical analysis.Results Mean CH and CRF in normal eyes (10.78 ± 1.6 (SD) mm Hg, 11.91 mm Hg ± 1.2) was clearly superior than in keratoconus group (8.01 ± 1.5 mm Hg, 7.32 ±1.8 mm Hg). However the difference of these parameters between keratoconus group without intracorneal rings and after corneal ring implantation (7.27mm Hg, 6.32 mm Hg) was not statistically significant (p ≤ 0.01). Mean follow-up period was of one year.Conclusion Corneal hysteresis and CRF values were significantly lower in keratoconic eyes than in normal eyes. But there is no marked differences if we compare these two biomechanical parameters in keratoconic corneas, before and after corneal ring implants. Improvements in the software accuracy of the ORA devices are needed to characterize corneal biomechanics.

Cabanás M, Alfonso JF, del-Buey MA, Peris C, Bilbao R, González F, Ortega-Usobiaga J, Llovet F. Protocolo de manejo de la ectasia corneal. In: Llovet F, Ortega-Usobiaga J. Cirugía Refractiva: Protocolos. Madrid: SEO; 2014; chapter 20: 227-230., Sep 1, 2014