Epitelización de la interfase después de la técnica de LASIK / Interface epithelialization after surgery LASIK technique

La epitelización de la interfase es una de las complicaciones secundarias a la cirugía refractiva corneal mediante la técnica de LASIK y de SMILE, que pueden influir de forma negativa sobre la calidad visual de los pacientes operados. Se presenta una paciente femenina de 51 años de edad operada de astigmatismo hipermetrópico compuesto de ambos ojos, hace aproximadamente dos años, mediante la técnica de LASIK con microquerátomo pendular. Desde hace 5 meses aproximadamente comenzó con disminución de la visión del ojo derecho, agudeza visual sin corrección del ojo derecho de 0,1 y con corrección de 0,3. Al examen oftalmológico se observaron depósitos blanquecinos en la entrecara del flap corneal, correspondientes a la epitelización de la interfase. Se decidió levantar el flap corneal para eliminar el tejido epitelial de la entrecara; se realizó queratectomía fototerapéutica y se colocó mitomicina C al 0,02 por ciento. La evolución de la paciente fue satisfactoria. La agudeza visual posterior al mes sin corrección del ojo derecho mejoró a 0,5 y con corrección a 0,9, sin mostrar signos de recurrencia(AU)

Interface epithelialization is one of the secondary complications of LASIK and SMILE refractive corneal surgery which may negatively affect the visual quality of operated patients. A female 51-year-old patient presents who underwent surgery about two years ago for compound hyperopic astigmatism of both eyes by LASIK technique with a pendular microkeratome. Approximately five months ago the patient began experiencing gradual visual loss in her right eye. Visual acuity of the right eye was 0.1 without correction and 0.3 with correction. Ophthalmological examination found whitish deposits in the corneal flap interface revealing interface epithelialization. It was decided to lift the corneal flap to remove the epithelial tissue from the interface. Phototherapeutic keratectomy was performed and 0.02 percent mitomycin C applied on the area. The patient's evolution was satisfactory. At one month, visual acuity of the right eye had risen to 0.5 without correction and 0.9 with correction, and no signs of recurrence were observed(AU)

[Impact of Different Percent Tissue Altered Values on Visual Outcome after Refractive Small Incision Lenticule Extraction (ReLEx SMILE)]. / Auswirkung verschiedener Percent-Tissue-altered-Werte auf das Behandlungsergebnis bei refraktiver Small Incision Lenticule Extraction (ReLEx SMILE).

Purpose To compare the visual outcomes after ReLEx SMILE treatment of eyes with low and high PTA values (PTA: percent tissue altered) within a follow-up period of up to 3 years and to assess whether a high PTA value might contribute to the development of keratectasia, as is the case for LASIK. Methods This retrospective analysis comprises results from 313 eyes (189 patients) with a PTA value of less than 40 % and of 373 eyes (213 patients) with a PTA value of at least 40 %. Preoperatively and up to 3 years after SMILE surgery, refraction values, monocular corrected (CDVA) and uncorrected distant visual acuity (UDVA) and wavefront data were evaluated. Results One to 3 years after surgery, the group with PTA < 40 % (PTA ≥ 40 %) had a loss of two Snellen lines in 1.1 % (0.0 %) of the cases. Loss of one line occurred in 1.1 % (3.6 %) of the eyes, whereas 97.7 % (96.4 %) remained unchanged or gained lines. With respect to predictability of the spherical equivalent, 92.0 % (78.6 %) of the eyes were within ± 0.5D and 97.7 % (92.9 %) were within ± 1.0D. The group with high PTA values displayed a slightly but significantly greater undercorrection of about 0,25D. 74.4 % (71.8 %) achieved UDVA of at least 20/20 and 96.5 % (87.1 %) achieved at least 20/25. The mean UDVA was - 0.03 ± 0.10logMAR (0.01 ± 0.12logMAR) and its mean difference to the preoperative CDVA was 0.00 ± 0.09logMAR (0.03 ± 0.12logMAR). Conclusion ReLEx SMILE is a safe and effective corneal refractive treatment, even for PTA values of 40 % and more. Eyes with high PTA values did not display any evidence of keratectasia development within the 3-year follow-up of this study.

Dry Eye after Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted in Situ Keratomileusis (FS-LASIK) for Myopia: A Meta-Analysis.

PURPOSE: To compare dry eye after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK) for correcting myopia. METHODS: CENTRAL, Embase and PubMed were searched in November 2016. All randomized controlled trials (RCTs) and prospective cohorts that compared dry eye after SMILE with FS-LASIK were selected. RESULTS: Five cohorts and one RCT were identified for comparing dry eye after SMILE (291 eyes) and FS-LASIK (277 eyes). The pooled results revealed that the SMILE and FS-LASIK groups did not differ significantly in terms of Schirmer's I test (SIT) and tear film osmolarity (TFO) at any postoperative visits. By contrast, tear break up time (TBUT; p = 0.04 for one month, p < 0.001 for three months, and p = 0.02 for six months) and ocular surface disease index (OSDI; p < 0.001 for one month and three months, and p = 0.006 for six months) were significantly worse in the FS-LASIK group than in the SMILE group at follow-up. At six months postoperatively, TBUT and TFO values in both the SMILE and FS-LASIK groups and OSDI scores in the SMILE group returned to preoperative levels, but SIT values in both groups (p = 0.02 for the SMILE group and p < 0.001 for the FS-LASIK group) and OSDI in the FS-LASIK group (p < 0.001) were still statistically impaired. CONCLUSION: Dry eye after both SMILE and FS-LASIK usually occurs transiently. SMILE does not show obvious superiority over FS-LASIK by exhibiting similar and acceptable objective parameters, and SMILE may have milder subjective symptoms.

Laser refractive surgery in the UK Biobank study: Frequency, distribution by sociodemographic factors, and general health, happiness, and social participation outcomes.

PURPOSE: To evaluate the frequency and distribution of laser refractive surgery in the United Kingdom by sociodemographic factors and outcomes of social participation and well-being. SETTING: Six regional recruitment centers in England and Wales. DESIGN: Cross-sectional epidemiological study. METHODS: Data were collected on sociodemographic factors and medical history; self-report on eyes/vision included reason for wearing optical correction, eye diseases, and treatment received (including refractive laser surgery). Mean spherical equivalent was used to categorize individuals as myopic (<-1.0 diopter) or hypertrophic (>+1.0 diopter). RESULTS: Between 2009 and 2010, 117 281 subjects recruited by UK Biobank undertook an ophthalmic assessment, including autorefraction. Of those with refractive error within a range eligible for laser refractive surgery (n = 60 352), 1892 (3.1%) reported having bilateral refractive surgery and 549 (0.9%) unilateral surgery. Frequency of bilateral surgery decreased with increasing age and was higher in women. Frequency did not vary with educational attainment or accommodation status but increased with income among working age adults. Social participation, for example, regular visits to a pub or social club, was more common among those who underwent surgery. Other eye conditions were reported by 28% of those reporting refractive surgery compared with 11% of those eligible for treatment but not reporting surgery. CONCLUSION: This study provides information not available routinely on the frequency and distribution of laser refractive surgery in an adult UK population. A high frequency of ocular conditions conventionally considered contraindications to laser refractive surgery raises the possibility that extant guidance on patient selection may not be followed.

Prevalence of laser vision correction in ophthalmologists who perform refractive surgery.

PURPOSE: To determine the prevalence of laser corneal refractive surgery (laser vision correction [LVC]) among ophthalmologists who perform these procedures and to assess the willingness of these ophthalmologists to recommend LVC to immediate family members. SETTING: Online survey with results analyzed at Surgivision Consultants, Inc., Scottsdale, Arizona, USA. DESIGN: Prospective randomized questionnaire study. METHODS: The 22-question Global Survey on Refractive Surgery in Refractive Surgeons was sent by e-mail to 250 ophthalmologists randomly selected from a database of 2441 ophthalmologists known to have performed LVC at some point in the past decade. Responses were solicited by e-mail, with subsequent telephone reminders to nonresponders. RESULTS: Responses were received from 248 (99.2%) of 250 queried individuals, of which 232 (92.8%) met the protocol criteria of currently working as refractive surgeons. Of the 232 subjects, 161 (69.4%) reported that they had refractive errors potentially amenable to treatment with LVC, not including presbyopia. Of the 161 ophthalmologists with treatable refractive errors, 54 (33.5%) reported they were not candidates for LVC for a variety of reasons and 107 (66.5%) reported they were candidates for LVC. Of the LVC candidates, 62.6% reported that they had an LVC procedure in their own eyes. Of the overall 232 subjects, more than 90% recommend LVC for adult members of their immediate family. CONCLUSIONS: Ophthalmologists who perform LVC were significantly more likely than the general population to have LVC in their own eyes. The prevalence of refractive errors was significantly higher among ophthalmologists performing refractive surgery than in the general population. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Distrofia de la membrana basal epitelial / epithelial basal membrane dystrophy

La distrofia de Cogan es la distrofia corneal anterior más común, frecuente en adultos del sexo femenino, entre 40-70 años de edad. Presentamos un caso de una paciente de 50 años de edad, del sexo femenino, quien refiere visión borrosa, lagrimeo y fotofobia. Al examen de la córnea en lámpara de hendidura se observan imágenes de color grisáceo en forma de huellas dactilares y de mapa. Esta afección es causada por alteraciones de la membrana basal epitelial que provoca la separación parcial o total del epitelio corneal. Generalmente asintomática, es la causa más frecuente de erosión corneal recurrente. Las opciones terapéuticas varían desde lubricantes, soluciones hipertónicas tópicas, lentes de contacto de vendaje, desbridamiento del epitelio central, micropunciones mecánicas o diatermia y fotoqueratectomía con láser excímer.

Cogan's dystrophy is the most common anterior corneal dystrophy in adult females aged 40-70 years of age. Here is a 50 years-old female patient suffering from blurred vision, weeping eyes and photophobia. On examination, grayish images were observed in the form of fingerprints and map. This disease is caused by alterations of the epithelial basal membrane bringing about partial or total removal of the corneal epithelium. Often asymptomatic, it is the most common cause of recurrent corneal erosion. Treatment options range from lubricants, topical hypertonic solutions, bandage contact lenses, central epithelial debridement, mechanical or diathermy micropuncture and excimer laser photokeratectomy.

Correlación entre morfometría corneal y la ametropía en el LASEK / Correlation between corneal morphometry and ametrophy in LASEK

Objetivo: establecer la correlación entre los cambios morfométricos corneales y la magnitud de la ametropía tratada hasta el año de cirugía corneal con láser de excímeros por la técnica LASEK. Métodos: se realizó una investigación observacional, descriptiva, longitudinal y prospectiva. La muestra quedó constituida por 56 pacientes 111 ojos operados con LASEK en el Hospital Abel Santamaría Cuadrado, en Pinar del Río, de noviembre de 2010 a junio de 2011. Se utilizó el microscopio confocal ConfoScan 4 de NIDEK para la obtención y estudio de las imágenes in vivo del tejido corneal. Se programó en modo escaneo automático, con fijación central, velocidad de adquisición de la imagen a 25 imágenes por segundo, magnificación de 500x, resolución lateral de 0,6 ìm/píxel, con 350 imágenes por escaneo, distancia de trabajo de 1,98 mm. Se utilizaron métodos de estadística descriptiva, correlación de Pearson y regresión lineal. Resultados: se obtuvo posterior a LASEK correlación estadísticamente significativa entre la magnitud de la ametropía tratada y las variables: paquimetría, grosor del haze corneal y densidad de queratocitos en estroma anterior. Conclusiones: mientras mayor es la magnitud de la ametropía tratada con LASEK, menor es el valor de paquimetría y la densidad de queratocitos en el estroma anterior(AU)

Objective: to establish the correlation between the corneal morphometric changes and treated ametropia one year after the corneal surgery with Excimer laser using LASEK. Methods: prospective, observational, descriptive and longitudinal study was conducted. The sample was 111 eyes from 56 patients, who were operated on with LASEK at Abel Santamaría hospital in Pinar del Río province, Cuba from November 2010 through June 2011. NIDEK´s Confocal ConfoScan 4 microscopy was used to obtain and to study the in vivo corneal tissue images. The equipment was set in automatic scanning, with central fixing, image taking speed of 25 image/sec, 500x magnifying, lateral resolution of 0,6 im/pixel, 350 scanned images, and operating distance of 1,98 mm. Summary statistics, Pearson´s correlation and linear regression methods were used. Results: after LASEK, an statistically significant correlation was observed between the size of treated ametropia and the studied variables pachymetry, corneal haze thickness and keratocyte density in the anterior stromaConclusions: as the size of ametropia treated with LASEK increases, the values of pachymetry and keratocyte density in the anterior stroma decreases(AU)

Correlación entre morfometría corneal y la ametropía en el LASEK / Correlation between corneal morphometry and ametrophy in LASEK

OBJETIVO: establecer la correlación entre los cambios morfométricos corneales y la magnitud de la ametropía tratada hasta el año de cirugía corneal con láser de excímeros por la técnica LASEK. MÉTODOS: se realizó una investigación observacional, descriptiva, longitudinal y prospectiva. La muestra quedó constituida por 56 pacientes (111 ojos) operados con LASEK en el Hospital «Abel Santamaría Cuadrado¼, en Pinar del Río, de noviembre de 2010 a junio de 2011. Se utilizó el microscopio confocal ConfoScan 4 de NIDEK para la obtención y estudio de las imágenes in vivo del tejido corneal. Se programó en modo escaneo automático, con fijación central, velocidad de adquisición de la imagen a 25 imágenes por segundo, magnificación de 500x, resolución lateral de 0,6 ìm/píxel, con 350 imágenes por escaneo, distancia de trabajo de 1,98 mm. Se utilizaron métodos de estadística descriptiva, correlación de Pearson y regresión lineal. RESULTADOS: se obtuvo posterior a LASEK correlación estadísticamente significativa entre la magnitud de la ametropía tratada y las variables: paquimetría, grosor del haze corneal y densidad de queratocitos en estroma anterior. CONCLUSIONES: mientras mayor es la magnitud de la ametropía tratada con LASEK, menor es el valor de paquimetría y la densidad de queratocitos en el estroma anterior.

OBJECTIVE: to establish the correlation between the corneal morphometric changes and treated ametropia one year after the corneal surgery with Excimer laser using LASEK. METHODS: prospective, observational, descriptive and longitudinal study was conducted. The sample was 111 eyes from 56 patients, who were operated on with LASEK at "Abel Santamaría" hospital in Pinar del Río province, Cuba from November 2010 through June 2011. NIDEK´s Confocal ConfoScan 4 microscopy was used to obtain and to study the in vivo corneal tissue images. The equipment was set in automatic scanning, with central fixing, image taking speed of 25 image/sec, 500x magnifying, lateral resolution of 0,6 im/pixel, 350 scanned images, and operating distance of 1,98 mm. Summary statistics, Pearson´s correlation and linear regression methods were used. RESULTS: after LASEK, an statistically significant correlation was observed between the size of treated ametropia and the studied variables pachymetry, corneal haze thickness and keratocyte density in the anterior stroma CONCLUSIONS: as the size of ametropia treated with LASEK increases, the values of pachymetry and keratocyte density in the anterior stroma decreases.

Poder corneal poscirugía fotoablativa en miopes por sistema scheimpflug pentacam vs. método de maloney / Postsurgical photoablative corneal power in myopic patients by using scheimpflug pentacam system vs. maloney method

OBJETIVO: comparar las queratometrías obtenidas por el Pentacam en ojos miopes operados con excímer láser y las calculadas a través del método de Maloney, en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer", de enero a marzo de 2013. MÉTODOS: se realizó un estudio prospectivo en 50 ojos de 26 pacientes miopes operados con láser, donde se calculó la queratometría promedio mediante el método de Maloney y se comparó con los valores brindados por el Pentacam: valor queratométrico total central y equivalent K- reading power de los mapas a color, así como el true net power (queratométrico total a 3,0 mm) y las lecturas queratométricas a distintos diámetros del programa Holladay Report. Se compararon las queratometrías preoperatoria media de la historia clínica y la estimada aportada por el Pentacam. El análisis estadístico se realizó con la prueba T para datos pareados, y se utilizó una significación del 95 %. RESULTADOS: no hubo diferencias estadísticas significativas entre las queratometrías del método de Maloney, el equivalent K- reading power y las lecturas de queratometría efectivas a diferentes diámetros. La de 3,0 mm mostró la menor diferencia. El resto de las mediciones difirieron de forma significativa. No se encontraron diferencias entre las queratometrías en el preoperatorio. CONCLUSIONES: el Pentacam aporta poderes corneales que no difirieren estadísticamente de los obtenidos por el método de Maloney en ojos miopes con cirugía fotoablativa previa.

OBJECTIVE: to compare the keratometries taken by Pentacam system in miopic patients operated on with excimer laser refractive surgery and those of Maloney method in the "Ramón Pando Ferrer" Cuban Institute of Ophthalmology from January to March of 2013. METHODS: aprospective study was conducted in 50 eyes from 26 patients operated on with excimer laser. The average keratometry was estimated by Maloney´s method and then compared with the values provided by the Pentacam system in terms of total central keratometric value and equivalent K-reading power of color maps, as well as true net power (total keratometric value at 3,0 mm) and equivalent keratometric readings at different diameters of Holladay Report program. Preoperative average keratometries in the medical history were compared with those estimated by Pentacam. Paired t test and 95 % significance level were used for the statistical analysis. RESULTS: there were no significant statistical differences among the keratometries taken by Maloney method, the equivalent K-reading power and the equivalent keratometric readings at different diameters, being that of 3 mm the more accurate. The rest of the measurements differed in a significant way. There were no differences among the preoperative keratometries. CONCLUSION: Pentacam equipment provides corneal powers that did not statistically differ from the ones obtained by Maloney method in myopic eyes with previous excimer laser surgery.

[Socioeconomical comparison between treated and untreated candidates for laser refractive surgery in mid-Hesse]. / Sozioökonomischer Vergleich zwischen laserrefraktivbehandelten und unbehandelten Patienten in Mittelhessen.

PURPOSE: The aim of this study was to explore the possible economic and social differences between patients who decided to undergo laser refractive surgery and those,who did not. PATIENTS AND METHODS: We included only patients who received a recommendation for excimer laser surgery at their first examination at the Department of Ophthalmology, University of Marburg. Eighty-nine candidates who decided not to undergo refractive surgery (NOP) and 100 patients who underwent the operation were surveyed either by telephone or by letter. The standardised questionnaire contained 17 or 20, respectively, questions. RESULTS: No statistically significant differences concerning age, sex, gross income, marital status could be found. Patients of the two groups statistically differed in their housing conditions: 41.6 % of the NOP group lived in a tenancy as compared with 17 % of the OP group (p < 0,001). 89.9 % of the non-operated candidates had to carry the costs of surgery themselves, compared with only 71 % of the operated patients. A considerably larger proportion of the OP group than of the NOP group participates in sports (92 vs. 81 %, p = 0.031) and may accordingly feel more uncomfortable with wearing glasses or contact lenses during sports than the compared group (71 vs. 50,7 %, p = 0.002). The main part of the OP group use the media to form their opinion towards refractive surgery (36 %), primarily the print media (25 %). In the NOP group the media does not play such as an important role (20.2 %). The opinion of their optician (11.2 %, but only 1 % of the OP group) seems to be more important. The main reason for not undergoing refractive surgery were the costs of the surgery (50 answers) and the lack of a guarantee for being absolutely independent of optical aids (glasses, lenses) after the operation (41 answers). CONCLUSION: In the region of mid-Hessen differences in the profile of candidates who do decide not to undergo refractive surgery and those who do can be found. These differences concern the housing conditions, the financiability of the surgical treatment, the sport activities and the preoperative discomfort with visual aids.

A boundary element model of the human eye undergoing laser thermokeratoplasty.

In the present paper, a three-dimensional radially symmetric boundary element model of the human eye is proposed for simulating changes in corneal temperature during treatment of laser thermokeratoplasty. Energy absorption inside the cornea is modeled using the Beer-Lambert law. Heat transfer inside the eye is assumed to be governed by the classical heat diffusion equation. The resulting initial-boundary value problem is solved numerically using a time-stepping boundary element method. The temperature field is calculated for heating by both the pulsed laser and the continuous wave laser. The results obtained are compared with those from other models found in the literature.

[First Brazilian refractive surgery survey]. / Primeiro censo brasileiro em cirurgia refrativa.

PURPOSE: To perform the first Brazilian refractive surgery survey. METHODS: Between August 2001 and February 2002, a questionnaire was mailed to 7890 Brazilian ophthalmologists. The questionnaire presented questions about demographic aspects, technology, instruments, market, trends, practice patterns and cost of refractive surgery. RESULTS: Nine hundred and twenty questionnaires (11.67%) were answered. LASIK is the preferred technique for correction between +5.00 and -7.00 D. The mostly used excimer laser is Nidek EC 5000, and Hansatome is the mostly used microkeratome. Others aspects like: demographic, techniques, practice patterns, trends, market, and pre-, intra- and postoperative care, were analyzed. CONCLUSION: With this survey, the Brazilian ophthalmologists can observe and monitor these aspects of refractive surgery in Brazil, and compare them with others surveys.