Comparison of corneal refractive power and visual quality after LASEK, TransPRK or FS-LASIK / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the corneal refractive power and visual quality after three kinds of corneal refractive surgery: laser subepithelial keratomileusis(LASEK), transepithelial photorefractive keratectomy(TransPRK)and femtosecond laser assisted in situ keratomileusis(FS-LASIK).METHODS: Retrospective study. A total of 232 patients(464 eyes)who underwent elective corneal refractive surgery in our hospital from January 2021 to December 2022 were selected as the study subjects. They were divided into the LASEK group of 70 cases(140 eyes), TransPRK group of 76 cases(152 eyes), and FS-LASIK group of 86 cases(172 eyes)according to the different surgical choices made by the patients. Uncorrected visual acuity(UCVA), visual quality, biomechanical stability, tear film break-up time(BUT), Schirmer Ⅰ test(SⅠt)and quality of life were compared among the three groups at 1 and 3 mo postoperatively.RESULTS: The UCVA of the three groups significantly improved at 1 and 3 mo postoperatively, the total high-order aberrations, spherical aberration, horizontal coma, and vertical coma of the entire cornea were significantly increased, while the biomechanical stability in all three groups were significantly reduced(all P<0.05). At 3 mo postoperatively, the biomechanical stability in the TransPRK and LASEK groups were higher than those of the FS-LASIK group(all P<0.05), and the TransPRK group had higher quality of life scores than the LASEK group and FS-LASIK group(P<0.05). Furthermore, there was no significant difference in preoperative or postoperative BUT and SⅠt among the three groups(all P>0.05).CONCLUSION:In the treatment of ametropia, LASEK, TransPRK and FS-LASIK all have certain effects, and have similar results in improving UCVA and increasing visual quality. However, TransPRK and LASEK have more stable biomechanical properties than FS-LASIK, and have better efficacy in improving patients' quality of life.

The Effect of Anti-glaucoma Eyedrops and 0.1% Fluorometholone on Myopic Regression after LASIK or LASEK

PURPOSE: To evaluate the effect of combined medical treatment with anti-glaucoma eyedrops and 0.1% fluorometholone on visual acuity and refractive errors in patients complaining of blurred vision due to myopic regression after laser-assisted in-situ keratomileusis (LASIK) or laser-assisted sub-epithelial keratectomy (LASEK). METHODS: This study comprised 155 patients (155 eyes) who were diagnosed with myopic regression after LASIK or LASEK and received medical treatment from January 2015 to January 2016. The visual acuity and refractive errors were compared before and after medical treatment and evaluated to determine whether the results differ between LASIK and LASEK. RESULTS: The mean time of medical treatment was 64.1 ± 36.8 months after surgery. The responder group whose vision was improved and whose myopic error was decreased after medical treatment was comprised of 63 patients (41%). Their visual acuity in this group improved -0.21 ± 0.11 logMAR, and the amount of myopic error decreased 0.56 ± 0.32 diopters. The full responder group was 24 patients (15%), and the partial responder group was 39 patients (26%). The frequency of response to medical treatment was higher after LASIK than after LASEK, but the difference was not statistically significant. CONCLUSIONS: The combined medical treatment with anti-glaucoma eyedrops and 0.1% fluorometholone was effective in 41% of patients with regard to visual acuity improvement when used for post-LASIK or post-LASEK myopic regression. The medical treatment was effective after both LASIK and LASEK.

Comparison of 10-year Clinical Results between Laser in situ Keratomileusis and Surface Ablation for Moderate to High Myopia

PURPOSE: To compare the long-term prognosis of laser in situ keratomileusis (LASIK) and surface ablation in moderate to high myopia. METHODS: A retrospective study including 87 eyes of 44 myopic patients treated with LASIK or surface ablation from 1995 to 2005 was performed. Follow-up visits were performed at 3 months, 1 year, 5 years, and 8 years. All treated eyes were divided into 2 groups according to preoperative spherical equivalent (SE)- moderate myopia (<-6.0 diopters [D]) and high myopia (≥-6.0 D). The main outcome measures were postoperative uncorrected visual acuity (UCVA), best corrected visual acuity, SE, mean keratometry, safety index, efficacy index, predictability, and complications. RESULTS: Mean SE was -7.05 ± 2.49 D in the LASIK group and -5.25 ± 1.23 D in the surface ablation group. The 10-year SE was -1.78 ± 1.22 D in the LASIK group and -1.35 ± 1.09 D in the surface ablation group, and there was no statistical difference between the 2 groups. At 10 years postoperatively, UCVA was log MAR 0.155 ± 0.161 in the LASIK group and log MAR 0.095 ± 0.140 in the surface ablation group. There were no significant differences in postoperative mean SE, safety index, efficacy index, or complications between the LASIK and surface ablation group at 10 years. CONCLUSIONS: This 10-year follow-up study shows that LASIK and surface ablation for moderate to high myopia have no statistical differences in mean SE, safety index, efficacy index, or complications.

Selección del paciente para cirugía refractiva: actualización / Update on the selection of patients for refractive surgery

Se realiza una búsqueda de la literatura más actualizada de los últimos cinco años enfocada en publicaciones de expertos y basada principalmente en una revisión realizada recientemente en la revista Current Opinion in Ophthalmology por un grupo de investigadores de la Universidad de Baltimore, Maryland (EE.UU.) sobre las contraindicaciones actuales de la cirugía refractiva. La Academia Americana de Oftalmología publica periódicamente directrices de patrones de práctica para la cirugía refractiva láser. El propósito de esta revisión es proporcionar una actualización sobre las contraindicaciones actuales y los detalles específicos relacionados con la cirugía refractiva láser(AU)

The present paper made a search for the most updated literature in the last five years, focused on expert publications and based on a recent review appeared in Current Opinion in Ophthalmology Journal by a group of researchers from the University of Baltimore in Maryland, United States of America on the current counter indications of the refractive surgery. The American Academy of Ophthalmology systematically publishes the practical guidelines for laser refractive surgery. The objective of this review was to provide update on the current counter indications and the specific details of the laser refractive surgery(AU)

Clinical Outcome of Retreatment after Refractive Surgery

PURPOSE: To evaluate the clinical outcome of retreatment after refractive surgery. METHODS: Retrospective analysis of 38 eyes of 24 patients who received retreatment surgery after refractive surgery from August 2008 to May 2013 was performed. Pre-initial surgery characteristics and the reason for retreatment were investigated, and preand post-retreatment uncorrected visual acuity, best corrected visual acuity, safety index, efficacy index, predictability, and postoperative complication were also investigated. RESULTS: Age at initial refractive surgery and retreatment were 28.50 +/- 7.29 years (17-49 years) and 31.21 +/- 6.49 years (21-49 years). Reasons for retreatment were myopic regression in 36 eyes (94.7%) and overcorrection in two eyes (5.3%). Methods of retreatment were laser subepithelial keratomileusis (LASEK) in 31 eyes (81.6%) and laser-assisted in situ keratomileusis (LASIK) in seven eyes (18.4%). Safety index values for all were above 1.0 and efficacy index values were 0.92, 0.93, and 0.95 in postoperative examination at 1 month, 3 months, and 6 months, respectively. No eye showed a decrease in best corrected visual acuity. One eye had transient hyperopia after retreatment, and two eyes had postoperative corneal opacity, but no eye experienced significant alteration in visual prognosis. CONCLUSIONS: Retreatment after refractive surgery was an efficient and safe clinical course in our clinic. No long-term complications were observed, and uncorrected visual acuity and refractive errors significantly improved after retreatment. In particular, LASEK can be considered as a safe and efficient retreatment modality without risk of keratectasia.

Surface Ablation with 0.02% Mitomycin C for Retreatment after LASIK and LASEK

PURPOSE: To evaluate the efficacy and safety of surface ablation with mitomycin C (MMC) for the retreatment of refractive errors following laser-assisted in-situ keratomileusis (LASIK) and laser-assisted sub-epithelial keratectomy (LASEK). METHODS: In this retrospective clinical study conducted at a single center, we evaluated 23 eyes that received surface ablation with MMC (0.02%, 20 seconds) between 2009 and 2013 for the treatment of residual refractive errors following myopic LASIK and LASEK. All eyes were evaluated for corneal thickness, initial refractive error, time interval to retreatment, amount of retreatment, duration of postoperative topical steroids use as well as uncorrected vision, spherical equivalent and corneal haziness preoperatively and 1, 3, 6 and 12 months postoperatively. RESULTS: Initially corrected myopia in the LASIK group was -6.47 +/- 2.17 D and -5.68 +/- 2.51 D in the LASEK group. Mean time between initial and retreatment by surface ablation was 11.88 +/- 5.59 months for LASIK and 14.07 +/- 10.10 for LASEK. Retreat amount was 1.49 +/- 0.36 D after LASIK and -1.65 +/- 0.41 D after LASEK. At postoperative 12 months, uncorrected visions were -0.061 +/- 0.886 (log MAR) in the LASIK group and -0.004 +/- 0.745 (log MAR) in the LASEK group and spherical equivalents were -0.55 +/- 0.56 D in the LASIK group and 0.36 +/- 0.33 D in the LASEK group. Postoperative hazes developed in 1 of 8 LASIK eyes and 3 of 15 LASEK eyes which resolved with application of topical steroid for 2-3 months postoperatively. CONCLUSIONS: Surface ablation with 0.02% MMC is safe and highly effective for treating myopic regression following LASIK or LASEK. Application of 0.02% MMC for 20 seconds was effective in preventing postoperative haze formation and maintaining stable vision and spherical equivalent at 12 months after retreatment.

Surface Ablation with 0.02% Mitomycin C for Retreatment after LASIK and LASEK

PURPOSE: To evaluate the efficacy and safety of surface ablation with mitomycin C (MMC) for the retreatment of refractive errors following laser-assisted in-situ keratomileusis (LASIK) and laser-assisted sub-epithelial keratectomy (LASEK). METHODS: In this retrospective clinical study conducted at a single center, we evaluated 23 eyes that received surface ablation with MMC (0.02%, 20 seconds) between 2009 and 2013 for the treatment of residual refractive errors following myopic LASIK and LASEK. All eyes were evaluated for corneal thickness, initial refractive error, time interval to retreatment, amount of retreatment, duration of postoperative topical steroids use as well as uncorrected vision, spherical equivalent and corneal haziness preoperatively and 1, 3, 6 and 12 months postoperatively. RESULTS: Initially corrected myopia in the LASIK group was -6.47 +/- 2.17 D and -5.68 +/- 2.51 D in the LASEK group. Mean time between initial and retreatment by surface ablation was 11.88 +/- 5.59 months for LASIK and 14.07 +/- 10.10 for LASEK. Retreat amount was 1.49 +/- 0.36 D after LASIK and -1.65 +/- 0.41 D after LASEK. At postoperative 12 months, uncorrected visions were -0.061 +/- 0.886 (log MAR) in the LASIK group and -0.004 +/- 0.745 (log MAR) in the LASEK group and spherical equivalents were -0.55 +/- 0.56 D in the LASIK group and 0.36 +/- 0.33 D in the LASEK group. Postoperative hazes developed in 1 of 8 LASIK eyes and 3 of 15 LASEK eyes which resolved with application of topical steroid for 2-3 months postoperatively. CONCLUSIONS: Surface ablation with 0.02% MMC is safe and highly effective for treating myopic regression following LASIK or LASEK. Application of 0.02% MMC for 20 seconds was effective in preventing postoperative haze formation and maintaining stable vision and spherical equivalent at 12 months after retreatment.

The Incidence of Increased Intraocular Pressure when Using 0.1% Fluorometholone after Photorefractive Keratectomy

PURPOSE: To analyze the time and incidence of increased intraocular pressure (IOP) induced by 0.1% fluorometholone used to prevent corneal haze after photorefractive keratectomy (PRK). METHODS: The present study included 826 patients (826 eyes) who underwent PRK between November 2012 and October 2013 and were followed up for more than 6 months. After surgery the patients were treated with 0.1% fluorometholone for 3-6 months according to their corneal conditions. The time and incidence was analyzed with the time and incidence when anti-glaucoma eye drops were used. RESULTS: Anti-glaucoma eye drops were used in 312 eyes (38%). The anti-glaucoma eye drops were started before 4 weeks postoperatively in 105 eyes (13%) and postoperatively at 5-8 weeks in 86 eyes (10%), at 9-12 weeks in 83 eyes (10%), at 13-16 weeks in 25 eyes (3%) and after 17 weeks in 13 eyes (2%). CONCLUSIONS: The overall incidence of increased IOP when treated with 0.1% fluorometholone for 3-6 months after PRK was approximately 38%. The incidence of increased IOP in each month for the first 3 months was almost identical implying that the longer 0.1 fluorometholone was used, the higher incidence of increased IOP occurred. These results can be helpful in educating patients regarding the risk of increased IOP and determining the follow-up period after PRK.

The Incidence of Increased Intraocular Pressure when Using 0.1% Fluorometholone after Photorefractive Keratectomy

PURPOSE: To analyze the time and incidence of increased intraocular pressure (IOP) induced by 0.1% fluorometholone used to prevent corneal haze after photorefractive keratectomy (PRK). METHODS: The present study included 826 patients (826 eyes) who underwent PRK between November 2012 and October 2013 and were followed up for more than 6 months. After surgery the patients were treated with 0.1% fluorometholone for 3-6 months according to their corneal conditions. The time and incidence was analyzed with the time and incidence when anti-glaucoma eye drops were used. RESULTS: Anti-glaucoma eye drops were used in 312 eyes (38%). The anti-glaucoma eye drops were started before 4 weeks postoperatively in 105 eyes (13%) and postoperatively at 5-8 weeks in 86 eyes (10%), at 9-12 weeks in 83 eyes (10%), at 13-16 weeks in 25 eyes (3%) and after 17 weeks in 13 eyes (2%). CONCLUSIONS: The overall incidence of increased IOP when treated with 0.1% fluorometholone for 3-6 months after PRK was approximately 38%. The incidence of increased IOP in each month for the first 3 months was almost identical implying that the longer 0.1 fluorometholone was used, the higher incidence of increased IOP occurred. These results can be helpful in educating patients regarding the risk of increased IOP and determining the follow-up period after PRK.

Clinical Efficacy of Topical Diquafosol Tetrasodium after Laser Epithelial Keratomileusis

PURPOSE: To evaluate the clinical effectiveness of topical diquafosol tetrasodium (DQS) after laser epithelial keratomileusis (LASEK). METHODS: This randomized prospective study included 97 eyes of 49 patients who were scheduled for LASEK. Patients in the DQS group used both 0.3% sodium hyaluronate and 3% DQS for 3 months after surgery while patients in the control group used only 0.3% sodium hyaluronate. Corneal staining score, tear film break-up time (TF-BUT), Schirmer test and ocular surface disease index (OSDI) were evaluated before surgery and 2, 4, 8, 12 and 16 weeks after surgery. RESULTS: There was no significant difference in visual acuity, spherical equivalent and corneal haziness between the 2 groups after surgery. Corneal staining score was significantly lower in the DQS group than in the control group 2 weeks after LASEK (p < 0.01) and increased in the control group after LASEK compared with the preoperative value (2 weeks after LASEK, p < 0.01), but decreased in the DQS group (12 and 16 weeks after LASEK, p < 0.05). TF-BUT was significantly higher in the DQS group than in the control group 2 to 16 weeks after LASEK (p < 0.01) and increased values were observed in the DQS group after LASEK compared with the preoperative value (4 to 16 weeks after LASEK, p < 0.05). The mean OSDI was significantly higher 4 to 16 weeks after LASEK in the control group than in the DQS group (p < 0.01). CONCLUSIONS: Subjective dry eye symptoms and objective markers were worse for 4 weeks after LASEK. The use of 3% DQS for 12 weeks after surgery improved these symptoms and markers with the effect lasting 16 weeks after LASEK.

Short-Term Clinical Results of Hyperopic LASEK in Korean Patients

PURPOSE: To evaluate short-term clinical outcomes following hyperopic laser-assisted subepithelial keratomileusis (LASEK) in Korean patients. METHODS: This retrospective study included 18 eyes of 10 patients who underwent hyperopic LASEK between May 2005 and March 2013 in Seoul National University Hospital. Visual acuity and spherical equivalent were evaluated preoperatively and at 1 and 3 months postoperatively. High order aberrations and contrast sensitivity were measured before and 3 months after the operation. Alternative prism cover test (APCT) was performed both preoperatively with correction and postoperatively without correction. RESULTS: The mean age of patients was 32 +/- 11 years and the mean spherical equivalent refractive error was -2.95 +/- 1.24 diopters (D). Uncorrected visual acuities were log MAR +0.17 +/- 0.15 and log MAR +0.14 +/- 0.15 at postoperative 1 month and 3 months, respectively and showed no significant difference in best corrected visual acuity (+0.25 +/- 0.30). Spherical equivalent was -0.22 +/- 1.22 D at 1 month and 0.38 +/- 0.91 D at 3 months postoperatively. In 6 patients who had esotropia before the operation, APCT was 7.83 +/- 3.60 prism diopters (PD) esotropia at distance with correction preoperatively and 4.67 +/- 5.65 PD at distance without correction postoperatively. Three patients (16.7%) showed delayed wound healing with 1 (5.56 %) having persistent corneal opacity without significant visual loss. CONCLUSIONS: The effect of LASEK may be comparable for correcting hyperopia and esotropia when compared with the effect of LASIK in previous reports; however, delayed wound healing may be a concern.

Técnica de superficie (LASEK) en pacientes con alta miopía / Surface technique (LASEK) in patients with high myopia: en

Introducción: actualmente, uno de los grandes retos de la oftalmología es hallar el tratamiento idóneo para los pacientes con miopía elevada. Objetivo: identificar la línea evolutiva de estos afectados de acuerdo con los resultados visuales y la presencia de complicaciones posoperatorias. Métodos: se realizó un estudio descriptivo, longitudinal y retrospectivo de 22 pacientes (33 ojos) con miopía alta, entre -6,00 y -10,00 dioptrías, atendidos en el Servicio de Cirugía Refractiva del Centro Oftalmológico del Hospital General Docente "Enrique Cabrera" de La Habana, operados mediante la técnica de superficie LASEK desde enero del 2010 hasta junio del 2011. Resultados: predominaron el grupo etario de 20-29 años (54,5 %), las féminas (72,7 %) y el haze (45,5 %) como complicación posoperatoria. La mayoría de los pacientes (97,0 %) alcanzaron agudeza visual con corrección (entre 0,6 y 1,0) en el periodo posoperatorio; 60,6 % con equivalente esférico (entre -1,00 y 0,25 dioptrías) y 69,7 % con valores queratométricos de 39,05- 43,00 dioptrías. Conclusiones: el LASEK resultó efectivo en la corrección de la miopía alta, no exento de complicaciones, pero sin repercusión en la visión final alcanzada y en el grado de satisfacción después del proceder.

Introduction: at present, one of the great challenges of ophthalmology is to find the adequate treatment for the patients with high myopia. Objective: to identify the clinical course of these affected patients according to the visual results and the presence of postoperative complications. Methods: A descriptive, longitudinal and retrospective study of 22 patients (33 eyes) with high myopia, between -6,00 and -10,00 diopters, assisted in the Service of Refractive Surgery of the Ophthalmological Center from "Enrique Cabrera" Teaching General Hospital in Havana, operated by means of the LASEK surface technique was carried out from January, 2010 to June, 2011. Results: the age group 20-29 years (54.5%), the female sex (72.7%) and the haze (45.5%) as postoperative complication prevailed. Most of the patients (97.0%) reached a visual acuity with correction (between 0.6 and 1.0) in the postoperative period; 60.6% with spherical equivalent (between -1.00 and 0.25 diopters) and 69.7% with queratometric values of 39,05 - 43,00 diopters. Conclusions: the LASEK was effective in the correction of high myopia, with certain complications, but without negative result in the final vision reached and in the satisfaction after the procedure.

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.

Analysis of Postoperative Intraocular Pressure Underestimation Measured with Non Contact Tonometry after Corneal Refractive Surgery

PURPOSE: To analyze the postoperative intraocular pressure (IOP) underestimation measured with non-contact tonometry after corneal refractive surgery. METHODS: The postoperative IOP decrease measured with non-contact tonometry (NCT), regarded as IOP underestimation, was calculated in 253 LASIK patients and 281 LASEK patients. Multiple regression analysis was performed to determine the preoperative factors which affect postoperative IOP underestimation. The right eye results were reported in this paper. RESULTS: The postoperative IOP decrease was affected by age (r = -0.0420, p = 0.03), corneal ablation depth (r = 0.0466, p < 0.01), and operation method (LASIK or LASEK) (r = 0.6006, p < 0.01). For every 100 microm decrease of corneal thickness by LASIK, the IOP decreased 6.29 +/- 2.40 mm Hg in patients under 26 years of age and 6.12 +/- 2.53 mm Hg in patients above 26 years of age (p = 0.05). For every 100 microm decrease of corneal thickness by LASEK, the IOP decreased 5.77 +/- 2.37 mm Hg in patients under 26 years of age and 5.44 +/- 2.62 mm Hg in patients above 26 years of age (p = 0.05). CONCLUSIONS: The postoperative IOP underestimation measured with NCT was more prominent in younger-aged patients after LASIK than LASEK with deeper ablation depth.

Transient Myopic Shift Due to Increased Latent Accommodation after LASEK

PURPOSE: To investigate accommodation and progress of patients who showed myopia on manifest refraction in the early postoperative period after LASEK. METHODS: Forty-one eyes were included in the present study which had undergone LASEK surgery from February to March 2012. Seven eyes showed myopia over -0.25 D on manifest refraction at 1 month postoperatively, but showed decreased amount of myopia at 2 months postoperatively and were classified as group 1. The other 34 eyes were classified as group 2. The differences between cycloplegic and manifest refraction (CRSE-MRSE) were defined as the amount of latent accommodation and compared between the 2 groups. RESULTS: Amount of latent accommodation was 0.179 +/- 0.426 D in group 1 (7 eyes), 0.265 +/- 0.303 D in group 2 (34 eyes) preoperatively, 1.286 +/- 0.664 D in group 1, 0.368 +/- 0.536 D in group 2 at 1 month postoperatively, and 0.500 +/- 0.520 D in group 1, and 0.489 +/- 0.546 D in group 2 at 2 months postoperatively. The amount of latent accommodation in group 1 was significantly greater than that of group 2 one month postoperatively. As the amount of latent accommodation decreased, the amount of myopic shift decreased gradually over 2 months in group 1 after surgery. CONCLUSIONS: Transient myopic shift due to increased latent accommodation was observed in several patients one month postoperatively and the amount of myopic shift decreased with time without treatment. Thus, surgeons should consider cycloplegic refraction when planning treatment for patients with myopic regression.

Comparison of LASIK Mode Ablation and PRK Mode Ablation in LASEK Using MEL-80 Excimer Laser

PURPOSE: We compared laser assisted in situ keratomileusis (LASIK) mode and photorefractive keratectomy (PRK) mode ablation methods in laser subepithelial keratomileusis (LASEK) surgery using the MEL-80 excimer laser. METHODS: All patients were followed up for a minimum of 1 year. The PRK mode group consisted of 46 eyes of 23 patients and the LASIK mode group consisted of 97 eyes of 56 patients. The central corneal thickness (CCT), ablation thickness, manifest refractive error and uncorrected visual acuity were compared preoperatively, 1 month and 1 year postoperatively. Spherical equivalent (SE) of cycloplegic refraction at postoperative 1 month and the uncorrected visual acuity (UCVA) ratios of 1.0 or better at postoperative 1 year were compared between the two groups to evaluate clinical efficacy. RESULTS: The SE of refractive error, CCT and target corneal ablation thickness of the two groups were not significantly different preoperatively. The PRK mode group obtained an actual ablation mean thickness of 82.8% of the target and the LASIK mode group obtained an actual ablation mean thickness of 94.1% of the target at postoperative 1 month. In each group, a statistically significant difference was observed between the actual corneal ablation thickness and target corneal ablation thickness. In the PRK mode group, the mean SE of postoperative 1 month cycloplegic refraction was +0.24 +/- 0.47 D and in the LASIK mode group, +0.87 +/- 0.54 D, indicating a statistically significant difference between the two groups. One year postoperatively, the UCVA ratios of 1.0 or better were 83% in the PRK mode group and 96% in the LASIK mode group, showing a statistically significant difference between the two groups. However, SE of manifest refractive error and CCT in the two groups were not statistically different at postoperative 1 year. CONCLUSIONS: The LASIK mode ablation method showed better results than the PRK mode ablation method in postoperative UCVA prognosis after LASEK surgery using the MEL-80 excimer laser.

Modificaciones de la superficie corneal posterior al año de la cirugía / Changes in the posterior corneal surface one year after surgery

Objetivo: describir las modificaciones de la curvatura posterior corneal en pacientes sometidos a cirugía refractiva láser en el Instituto Cubano de Oftalmología Ramón Pando Ferrer en el período de enero-diciembre de 2011. Métodos: estudio descriptivo, longitudinal y prospectivo, con un universo de 257 pacientes (504 ojos) sometidos a cirugía refractiva láser. La muestra quedó conformada por 31 pacientes (59 ojos). Se analizaron las variables: edad, sexo, equivalente esférico, paquimetría preoperatoria, cantidad de ablación, estroma residual y diferencia de elevación posterior corneal, esta última obtenida del mapa de diferencia del tomógrafo Galilei con medición preoperatoria, al mes, 3 meses, 6 meses y 1 año de la cirugía. Con análisis de regresión múltiple se evaluaron dichos cambios con la paquimetría, cantidad de ablación, estroma residual y presión intraocular. Resultados: el equivalente esférico, paquimetría, cantidad de ablación, estroma residual y presión intraocular estaban dentro de los criterios de seguridad. La diferencia promedio de la elevación corneal posterior fue de 15,62 µm al mes y 11,78 µm a los 3 meses, 7,68 µm a los 6 meses y 3,22 µm al año con disminución significativa con el tiempo (p= 0,000). Se observó asociación con la paquimetría preoperatoria, el estroma residual y la presión intraocular. Conclusiones: la cirugía refractiva láser induce un aumento precoz en la elevación corneal posterior, con disminución progresiva en el tiempo. Los factores que más influyeron en estos cambios fueron el estroma residual, la paquimetría preoperatoria y la presión intraocular

Objective: to describe the changes of the posterior corneal curvature observed in patients who underwent laser-assisted refractive surgery at Ramón Pando Ferrer Cuban Institute ofOphthalmology from January through December 2011. Methods: a prospective, longitudinal and descriptive study of a sample of 31 patients (59 eyes) selected from a universe of 257 patients (504 eyes), who underwent laser-assisted refractive surgery. The analyzed variables were age, sex, spherical equivalent, pachymetry before surgery, ablation magnitude, residual stroma and difference in posterior corneal elevation. The latter was obtained from the Galilei´s tomograph difference map with measurements before surgery and one month, three months, six months and a year after surgery. Stepwise multiple regression analysis allowed evaluating such changes with pachymetry, ablation microns, residual stroma and intraocular pressure. Results: spherical equivalent, pachymetry, ablation microns, residual stroma and intraocular pressure were within the set safety criteria. The average difference of the posterior corneal elevation was 15,62 µm at one month, 15,62 µm three months, 7,68 µm six months and 3,22 µm one year after the surgery, with significant reduction as time goes by (p=0.000). Preoperative pachymetry, residual stroma and intraocular pressure were found to be related. Conclusions: laser-assisted refractive surgery causes an early increase of the posterior corneal elevation, with progressive reduction in time. The most influential factors were residual stroma, preoperative pachymetry and intraocular pressure

Corneal Endothelial Changes after Laser-Assisted Subepithelial Keratomileusis

PURPOSE: In order to investigate the safety of laser-assisted subepithelial keratomileusis (LASEK), corneal endothelial cells before and after the LASEK procedure were evaluated. METHODS: Thirty-six patients (72 eyes) who underwent LASEK between June 2010 and May 2011 were included in the present study. Parameters included corneal endothelial cell density (CD), coefficient of variation of the cell area (CV), and percentage of hexagonal cells (6A) which were all obtained by a specular microscope (Noncon ROBO sp 8000, Konan, Japan) before and 3, 6, and 12 months after LASEK. RESULTS: Preoperative CD was 2952 +/- 352 cells/mm2, and postoperative CD did not significantly change at 3, 6, and 12 months. Preoperative CV and 6A and postoperative CV and 6A at 12 months were not significantly different. Furthermore, correlation between change in corneal endothelial cell and degree of myopia correction was not statistically significant. CONCLUSIONS: LASEK appears to be a safe procedure for corneal endothelial cells over an extended period.

Corneal Endothelial Cell Changes after LASEK and M-LASEK

PURPOSE: In this study we evaluated the changes in the corneal endothelial cells before and after the operation among myopes in the M-LASEK group, on whom 0.02% mitomycin C (MMC) was used and in the LASEK group, on whom MMC was not used. METHODS: The corneal endothelial cell analysis was performed in 104 eyes of 57 subjects in the LASEK group and in 86 eyes of 48 subjects in the M-LASEK group before the operation, and 3 months and 12 months postoperatively. RESULTS: There were no statistically significant differences in the corneal endothelial cell density (CD), the cell area coefficient of variance (CV), and hexagonal cell rate (6A) between the 2 groups before the operation, and 3 months and 12 months postoperatively (p > 0.05). In the LASEK group, there were no statistically significant differences (p > 0.05) in CD when the numerical values before the operation and 3 months and 12 months after the operation were compared, but there were statistically significant differences in CV and 6A when comparing before the operation and 12 months postoperatively (p = 0.001, p = 0.034, respectively). In the M-LASEK group, there was a 2.8% statistically significant decrease (p = 0.004) in CD when the numerical values before the operation and 3 months after the operation were compared, but there were no statistically significant difference (p > 0.05) when the numerical values before the operation and 12 months after the operation were compared. In addition, there were no statistically significant differences (p > 0.05) in CV and 6A when the numerical values before the operation and 3 months and 12 months after the operation were compared. CONCLUSIONS: M-LASEK, contrary to LASEK, showed statistically significant differences in CD in short-term results such as 3 months postoperatively, but in long-term observation such as 12 months postoperatively, both groups showed no statistically significant differences.

Queratitis lamelar difusa después de un corte incompleto / Diffuse lamellar keratitis after incomplete corneal flap cut

La queratitis lamelar difusa es una inflamación estéril de la interfase lamelar que suele presentarse 24 horas después de la realización de la queratomileusis in situ asistida con láser y potencialmente puede comprometer la agudeza visual final. Se presenta un paciente de 25 años de edad con antecedentes de cirugía refractiva corneal mediante queratomileusis in situ con láser en el ojo derecho, que tuvo como complicación durante el acto quirúrgico un corte incompleto. En el posoperatorio inmediato se le diagnosticó una queratitis lamelar difusa. Se aplicó tratamiento local y se obtuvo la recuperación visual total del paciente con estabilidad del defecto refractivo. Esto permite posteriormente realizarle la corrección mediante cirugía refractiva de superficie

The diffuse lamellar keratitis is a sterile swelling of the lamellar interface which arises generally 24 hours after laser in situ keratomileusis and might affect the final visual acuity. A 25 years- old patient with history of corneal refractive surgery by laser in situ keratomileusis on his right eye was reported. He suffered from an incomplete corneal flap cut as complication during the surgical procedure, and a diffuse lamellar keratitis was detected at the immediate postsurgical visit. Total visual recovery and the refractive defect stability were attained through local treatment. This allows further correcting the defect by means of a surface refractive surgery in the future