Comparison of different correction formulas and measurement methods for the accurate determination of intraocular pressure after SMILE and FS-LASIK surgery.

BACKGROUND: To compare the accuracy of non-contact tonometry, Pentacam, and corneal visualization Scheimpflug technology (Corvis ST) for the measurement of intraocular pressure (IOP) after small incision lenticule extraction (SMILE) or femtosecond laser-assisted in situ keratomileusis (FS-LASIK) surgery. METHODS: A total of 49 patients (98 eyes) undergoing FS-LASIK or SMILE surgery at West China Hospital, Sichuan University from January to March 2021 were enrolled in this prospective, comparative, self-controlled study. IOP values were measured with non-contact tonometer, Pentacam, and Corvis ST before surgery and 1 month after surgery. Pentacam-derived postoperative IOP values were corrected using five correction formulas (Ehlers, Shah, Dresden, Orssengo-Pye, and Kohlhaas), while Corvis ST-derived values were corrected using a single formula. RESULTS: In the SMILE group, no significant differences were observed between the IOP values corrected with the Shah formula before and after surgery (t = 0.17, P = 0.869), whereas postoperative IOP values corrected with the other formulas were significantly different from the corresponding preoperative measurements (P < 0.05). In the FS-LASIK group, postoperative IOP values corrected with the Ehlers, Shah, or Corvis ST formulas were significantly different from the corresponding preoperative IOP measurements (P < 0.05), but no significant differences were observed between pre- and postoperative IOP values corrected with the Dresden (t = - 0.08, P = 0.941), Orssengo-Pye (t = - 0.52, P = 0.604), or Kohlhaas (t = 1.22, P = 0.231) formulas. CONCLUSIONS: Pentacam's Shah correction formula seemed to be the most appropriate method for accurately measuring postoperative IOP in patients undergoing SMILE surgery, while the Dresden, Orssengo-Pye, and Kohlhaas correction formulas of Pentacam were identified as the most reliable methods for estimating IOP in patients after FS-LASIK surgery.

Glaucoma Progression and its Relationship with Corrected and Uncorrected Intraocular Pressure in Eyes with History of Refractive Corneal Surgery.

PURPOSE: To investigate glaucoma progression and its relationship with corrected and uncorrected intraocular pressure (IOP) in patients with a history of refractive corneal surgery (RCS). METHODS: Totally, 56 eyes of 56 primary open-angle glaucoma patients who had a history of RCS were included. Mean keratometry and central corneal thickness were measured at the time of glaucoma diagnosis. Three IOP measurements, i.e., uncorrected IOP (UCIOP) and corrected IOP calculated by applying the Kohlhaas (CKIOP) and Ehlers (CEIOP) formulas, were used. Participants were categorized into two groups (low-teen [<15 mmHg] and high-teen [≥15 mmHg] groups) according to the mean follow-up IOP, in each of the three IOP measurements. Glaucoma progression was determined based on either structurally or functionally by stereoscopic optic disc/retinal nerve fiber layer photographs or visual field tests. Kaplan-Meier survival curves were compared between the low-teens group and high-teens group for each IOP measurement. Risk factors for glaucoma progression, including uncorrected and corrected IOP measurements, were analyzed using a Cox proportional-hazards model. RESULTS: Among total eyes, glaucoma progression was found in 19 (34%) eyes during 4.3 years of mean follow-up period. Individual values of uncorrected IOP and corrected IOP showed significant differences (p < 0.001). Incidence of glaucoma progression was higher in high-teens group than in low-teens group by corrected IOP values (both Kohlhaas and Ehlers, p = 0.006, 0.003), but not by uncorrected IOP values (p = 0.749). The cumulative probability of glaucoma progression was significantly greater in the high-teens group than in the low-teens group using the Elhers formula determined by Kaplan-Meier analysis (p = 0.030). CONCLUSIONS: For glaucoma eyes with history of RCS, high-teen group by corrected mean follow-up IOP showed more glaucoma progression than low-teen group. More intensive IOP-lowering treatment will be required for patient with high-teen follow-up corrected IOP to prevent glaucoma progression.

Efficacy at early stage after FS-LASIK with accelerated corneal collagen cross-linking / 国际眼科杂志(Guoji Yanke Zazhi)

· AIM:To evaluate the safety and efficacy at early stage after femtosecond laser-assisted excimer laser in situ keratomileusis (FS-LASIK) combined with collagen cross-linking.· METHODS:Totally 30 myopia patients (60 eyes) received FS-LASIK combined with collagen cross-linking from July 2016 to August 2017 in our hospital were tested the uncorrected visual acuity (UCVA),Ks,Kf,surface regular index (SRI),surface asymmetry index (SAI) by corneal topography (TMS) preoperatively,1,3mo after operation.The corneal compensated intraocular pressure (IOPcc),Goldmann correlated IOP value (IOPg),corneal resistance factor (CRF),corneal hysteresis (CH) tested by ocular response analyzer (ORA) were also observed.Ziemer Galilei Dual Scheimpflug Analyzer detected the anterior diopter and the corneal thickness.Endothelial cell density were examined.· RESULTS:The postoperative UCVA remained beyond 0.8 including 26 eyes (43％) of 1d,55 eyes (92％) of 1mo,50 eyes (83％) of 3mo.IOPcc,IOPg,CRF,CH at postoperative 1mo significantly decreased comparing with preoperative (P＜0.01).IOPcc,IOPg,CRF,CH at postoperative 3mo did not change significantly comparing with 1mo (P＞0.05).The corneal topographic map parameters of Ks and Kf significantly decreased at postoperative 1mo (P ＜ 0.01),while SRI and SAI increased significantly (P＜0.01) on comparison of 1mo and preoperative.Ks of postoperative 3mo was significantly higher than that of 1 mo (P＜0.05),while Kf did not change significantly (P＞ 0.05).There was a significant decrease in SRI and SAI between 3mo and 1mo after operation (P＜ 0.05).In Galileo analysis on comparison of 3mo and 1mo,Sim Ks,Sim Kf had 0.94D,0.95D growth and the front and back surface value of Kf increased more at 3mo postoperative (P＜0.01),while Ks was no significant difference (P＞ 0.05).There was no statistically significant difference in corneal thickness between the central point and the thinnest point (P＞ 0.05).There was no significant endothelial cell loss throughout follow up (3059.95±247.87/mm2 vs 3052.87± 267.71/mm2;t=0.279,P＞0.05).· CONCLUSION:Refractive corneal surgery combined with collagen cross linking for high degree,thin cornea,uneven thickness of the cornea,topographic anomalies except for the patients with keratoconus,play a role in stabilizing corneal shape and increasing corneal biomechanics early.

Efectividad del cálculo del lente intraocular por Pentacam y por el método de Maloney en pacientes con cirugía refractiva corneal previa / Effectiveness of the calculation of the intraocular lens by Pentacam and by Maloney's method in patients with previous refractive corneal surgery

Objetivo: comparar los resultados visuales de los pacientes con cirugía refractiva corneal, operados de catarata e implante de lente intraocular, calculado por el método de Maloney y por Pentacam. Métodos: se realizó un estudio descriptivo, prospectivo y longitudinal en 41 ojos de 31 pacientes con catarata y antecedentes de cirugía refractiva corneal, divididos aleatoriamente en dos grupos (1 y 2) con 23 y 18 ojos respectivamente, para calcular el poder corneal por el método de Maloney y por Pentacam, respectivamente, necesario para el cálculo de la lente intraocular a implantar. Resultados: la mayoría de los pacientes tenía antecedentes de queratotomía radial (90,24 pr ciento). El poder dióptrico medio de la lente mediante el método de Maloney fue de 18,8 ± 4,20, mientras que con la lectura queratométrica, medida a 4,0 mm del Pentacam, fue de 18 ± 4,20, con una diferencia media de 0,80 dioptrías ( p= 0,000) asociada a la prueba de los rangos con signo de Wilcoxon. El componente esférico posoperatorio promedio fue de -0,49 ± 0,65 dioptrías en el grupo 1 y de -0,57 ± 0,685 en el grupo 2, con una diferencia entre la esfera observada y la esperada de 0,16 y 0,15 dioptrías respectivamente (p= 0,906), asociada a la prueba U de Mann-Whitney. quedaron emétropes un 43,48 por ciento del grupo 1 y un 50 por ciento del grupo 2. Conclusiones: ambos métodos brindan resultados visuales favorables, pero el cálculo de la lente intraocular a partir de las lecturas queratométricas aportadas por el Pentacam ofrece mejores resultados visuales para los pacientes con antecedentes de cirugía refractiva corneal(AU)

Objective: to compare the visual results of patients operated from cataract and with intraocular lens implantation through corneal refractive surgery and estimated by Maloney's method and Pentacam camera. Methods: prospective, longitudinal and descriptive study conducted in 41 eyes from 31 patients with cataract and history of refractive corneal surgery. They were randomly assigned to two groups (1 and 2) with 23 and 18 eyes, respectively in order to estimate the corneal power of the intraocular lens to be implanted through Maloney's method and Pentacam camera. Results: most of patients had history of radial keratotomy (90.24 percent). The average dioptric power of the lens according to Maloney's method was 18.8 ± 4.20 whereas the kerametric reading, measured at 4.0 mm from Pentacam was 18 ± 4.20, with a mean difference of 0.80 dioptries ((p= 0,000) associated to Wilcoxon's sign range test. The average postoperative spheral component was -0.49 ± 0.65 D in group 1 and -0.57 ± 0.685 in group 2, with a difference between the observed and the expected sphere of 0.16 and 0.15 dioptries, respectively (p= 0.906), associated to Mann-Whitney's U test. In group 1, 43.48 percent and in group 2, 50 percent remained emetropes. Conclusions: Both methods provide favorable visual results, but the calculation of the intraocular lens power through the keratometric readings by Pentacam offers better visual results for patients with a history of refractive corneal surgery(AU)

Efectividad del cálculo del lente intraocular por Pentacam y por el método de Maloney en pacientes con cirugía refractiva corneal previa / Effectiveness of the calculation of the intraocular lens by Pentacam and by Maloney's method in patients with previous refractive corneal surgery

Objetivo: comparar los resultados visuales de los pacientes con cirugía refractiva corneal, operados de catarata e implante de lente intraocular, calculado por el método de Maloney y por Pentacam. Métodos: se realizó un estudio descriptivo, prospectivo y longitudinal en 41 ojos de 31 pacientes con catarata y antecedentes de cirugía refractiva corneal, divididos aleatoriamente en dos grupos (1 y 2) con 23 y 18 ojos respectivamente, para calcular el poder corneal por el método de Maloney y por Pentacam, respectivamente, necesario para el cálculo de la lente intraocular a implantar. Resultados: la mayoría de los pacientes tenía antecedentes de queratotomía radial (90,24 pr ciento). El poder dióptrico medio de la lente mediante el método de Maloney fue de 18,8 ± 4,20, mientras que con la lectura queratométrica, medida a 4,0 mm del Pentacam, fue de 18 ± 4,20, con una diferencia media de 0,80 dioptrías ( p= 0,000) asociada a la prueba de los rangos con signo de Wilcoxon. El componente esférico posoperatorio promedio fue de -0,49 ± 0,65 dioptrías en el grupo 1 y de -0,57 ± 0,685 en el grupo 2, con una diferencia entre la esfera observada y la esperada de 0,16 y 0,15 dioptrías respectivamente (p= 0,906), asociada a la prueba U de Mann-Whitney. quedaron emétropes un 43,48 por ciento del grupo 1 y un 50 por ciento del grupo 2. Conclusiones: ambos métodos brindan resultados visuales favorables, pero el cálculo de la lente intraocular a partir de las lecturas queratométricas aportadas por el Pentacam ofrece mejores resultados visuales para los pacientes con antecedentes de cirugía refractiva corneal(AU)

Objective: to compare the visual results of patients operated from cataract and with intraocular lens implantation through corneal refractive surgery and estimated by Maloney's method and Pentacam camera. Methods: prospective, longitudinal and descriptive study conducted in 41 eyes from 31 patients with cataract and history of refractive corneal surgery. They were randomly assigned to two groups (1 and 2) with 23 and 18 eyes, respectively in order to estimate the corneal power of the intraocular lens to be implanted through Maloney's method and Pentacam camera. Results: most of patients had history of radial keratotomy (90.24 percent). The average dioptric power of the lens according to Maloney's method was 18.8 ± 4.20 whereas the kerametric reading, measured at 4.0 mm from Pentacam was 18 ± 4.20, with a mean difference of 0.80 dioptries ((p= 0,000) associated to Wilcoxon's sign range test. The average postoperative spheral component was -0.49 ± 0.65 D in group 1 and -0.57 ± 0.685 in group 2, with a difference between the observed and the expected sphere of 0.16 and 0.15 dioptries, respectively (p= 0.906), associated to Mann-Whitney's U test. In group 1, 43.48 percent and in group 2, 50 percent remained emetropes. Conclusions: Both methods provide favorable visual results, but the calculation of the intraocular lens power through the keratometric readings by Pentacam offers better visual results for patients with a history of refractive corneal surgery(AU)

Queratometrías por Pentacam y método de Maloney en pacientes con catarata y cirugía refractiva corneal previa / Keratometries taken with Pentacam and Maloney method in patients with cataract and previous corneal refractive surgery

Objetivo: comparar las queratometrías obtenidas por el Pentacam y el método de Maloney en pacientes con catarata, operados previamente de cirugía refractiva corneal. Métodos: se realizó un estudio descriptivo, longitudinal, prospectivo y comparativo entre los valores queratométricos obtenidos mediante el método de Maloney y el Pentacam en pacientes con catarata y cirugía refractiva corneal previa. Se estudiaron 41 ojos de 31 pacientes distribuidos en dos grupos, con 23 y 18 ojos para Maloney y Pentacam respectivamente. La información de la base de datos fue procesada con el software SPSS versión 11.0 para Window. Se trabajó con un nivel de confianza del 95 por ciento y de error inferior al 0,05 por ciento. Resultados: en ambos grupos prevaleció el astigmatismo miópico (simple o compuesto), lo cual se encontró en 14 ojos (60,9 por ciento) del grupo 1 y 16 ojos (89 por ciento) del grupo 2. La mayoría de los ojos estudiados (37) tenían queratotomía radiada, y solo 4,3 del Grupo 1 y 1 del Grupo 2 tenían LASEK miópico. La queratometría promedio obtenida por el método de Maloney fue de 37,55 D, mientras que el valor promedio brindado por el Pentacam (EKR a 4,0 mm) fue de 39,18 D, con una diferencia promedio de 1,64 D, que fue significativa (p= 0,019). Conclusiones: los valores queratométricos aportados por el método de Maloney y las EKR a 4,0 mm del modo Holladay Report del Pentacam presentan diferencias significativas en pacientes con queratotomía radiada previa(AU)

Objective: to compare the keratometries with Pentacam and with Maloney method in patients with cataract, who had previously undergone refractive corneal surgery. Methods: comparative, prospective, descriptive and longitudinal study of keratometric values estimated with Pentacam camera and with Maloney's method in patients with cataract and previous corneal refractive surgery. Forty one eyes were distributed into two groups; twenty three were studied by Maloney method and 18 by Pentacam. Database information was processed by was processed by version 11.0 SPSS software for Windows. The confidence interval was 95 percent and the error margin below 0.05 percent. Results: myopic astigmatism (simple or compound) prevailed and it was found in 14 eyes (60.9 percent) of Group 1 and in 16 eyes (89 percent) of group 2. Most of the studied eyes (37) had radiated keratotomy and just 4.3 in group 1 and one in group 2 had myopic LASEK. The average keratometry with Maloney's method was 37.55 D whereas the average value provided by the Pentacam (EKR at 4,0 mm) was 39.18 D, with a significant average difference of 1.64 D (p= 0.019). Conclusions: the keratometric values estimated by Maloney's method and the EKR at 4,0 mm from the Holladay Report of Pentacam show significant differences in patients with previous radiated keratotomy(AU)

Queratometrías por Pentacam y método de Maloney en pacientes con catarata y cirugía refractiva corneal previa / Keratometries taken with Pentacam and Maloney method in patients with cataract and previous corneal refractive surgery

Objetivo: comparar las queratometrías obtenidas por el Pentacam y el método de Maloney en pacientes con catarata, operados previamente de cirugía refractiva corneal. Métodos: se realizó un estudio descriptivo, longitudinal, prospectivo y comparativo entre los valores queratométricos obtenidos mediante el método de Maloney y el Pentacam en pacientes con catarata y cirugía refractiva corneal previa. Se estudiaron 41 ojos de 31 pacientes distribuidos en dos grupos, con 23 y 18 ojos para Maloney y Pentacam respectivamente. La información de la base de datos fue procesada con el software SPSS versión 11.0 para Window. Se trabajó con un nivel de confianza del 95 por ciento y de error inferior al 0,05 por ciento. Resultados: en ambos grupos prevaleció el astigmatismo miópico (simple o compuesto), lo cual se encontró en 14 ojos (60,9 por ciento) del grupo 1 y 16 ojos (89 por ciento) del grupo 2. La mayoría de los ojos estudiados (37) tenían queratotomía radiada, y solo 4,3 del Grupo 1 y 1 del Grupo 2 tenían LASEK miópico. La queratometría promedio obtenida por el método de Maloney fue de 37,55 D, mientras que el valor promedio brindado por el Pentacam (EKR a 4,0 mm) fue de 39,18 D, con una diferencia promedio de 1,64 D, que fue significativa (p= 0,019). Conclusiones: los valores queratométricos aportados por el método de Maloney y las EKR a 4,0 mm del modo Holladay Report del Pentacam presentan diferencias significativas en pacientes con queratotomía radiada previa(AU)

Objective: to compare the keratometries with Pentacam and with Maloney method in patients with cataract, who had previously undergone refractive corneal surgery.Methods: comparative, prospective, descriptive and longitudinal study of keratometric values estimated with Pentacam camera and with Maloney's method in patients with cataract and previous corneal refractive surgery. Forty one eyes were distributed into two groups; twenty three were studied by Maloney method and 18 by Pentacam. Database information was processed by was processed by version 11.0 SPSS software for Windows. The confidence interval was 95 percent and the error margin below 0.05 percent. Results: myopic astigmatism (simple or compound) prevailed and it was found in 14 eyes (60.9 percent) of Group 1 and in 16 eyes (89 percent) of group 2. Most of the studied eyes (37) had radiated keratotomy and just 4.3 in group 1 and one in group 2 had myopic LASEK. The average keratometry with Maloney's method was 37.55 D whereas the average value provided by the Pentacam (EKR at 4,0 mm) was 39.18 D, with a significant average difference of 1.64 D (p= 0.019).Conclusions: the keratometric values estimated by Maloney's method and the EKR at 4,0 mm from the Holladay Report of Pentacam show significant differences in patients with previous radiated keratotomy(AU)

Cataract surgery on the previous corneal refractive surgery patient.

Cataract surgery in cases with previous corneal refractive surgery may be a major challenge for the ophthalmologist. The refractive outcome of the case deserves special attention in the preoperative planning process, which should be tailored for the type of prior refractive procedure: incisional, ablative under a flap, or on the corneal surface. Avoiding refractive surprise after cataract surgery in these cases is principally dependent on the accuracy of the intraocular lens calculation, together with the selection of the appropriate biometric formula for each case. Modern techniques for cataract surgery help surgeons to move toward the goal of cataract surgery as a refractive procedure free from refractive error. We give practical guidelines for the cataract surgeon in the management of these challenging cases.

Queratitis lamelar difusa después del Lasik / Diffuse lamellar keratitis after LASIK

OBJETIVO: Describir el comportamiento de la queratitis lamelar difusa como complicación después de emplear la técnica quirúrgica queratomileusis in situ con láser. MÉTODOS: Se realizó un estudio descriptivo, de corte transversal en el Servicio de Cirugía Refractiva Corneal del Instituto Cubano de Oftalmología "Ramón Pando Ferrer" en el último trimestre del año 2008. La muestra quedó conformada por 16 ojos a los que se les realizó la queratomileusis in situ con láser como técnica quirúrgica para corregir ametropía y que presentaron complicaciones con esta cirugía. Se analizaron variables como la agudeza visual sin corrección; los ojos con esta complicación fueron analizados según la clasificación de Linebarger. RESULTADOS: La frecuencia de queratitis lamelar difusa fue de 3,0 por cada 100. La agudeza visual no corregida se comportó entre 0,8 y 1,0 en 12 ojos de 16 afectados, el estadio 1 se presentó en 12 ojos. CONCLUSIONES: La queratitis lamelar difusa es una complicación poco frecuente, los casos que la padecieron alcanzaron una buena agudeza visual final sin corrección. Predominó la forma leve de este cuadro.

OBJECTIVE: To describe the situation of Diffuse lamellar keratitis as a complication after in situ keratomileusis with laser. METHODS: A descriptive cross-sectional study was carried out in the Refractive Corneal Service of "Ramón Pando Ferrer" Cuban Institute of Ophthalmology during the last quarter of 2008. The sample embraced 16 eyes that underwent in situ keratomileusis plus laser as the refractive procedure to correct ametropy and presented with some complications. Visual acuity without correction was one the analyzed variables and the eyes with this type of complication were classified according to Linebarger´s classification. RESULTS: The diffuse lamellar keratitis frequency was 3.0 per one hundred cases, the visual acuity without correction was 0.8 to 1.0 in 12 out of 16 eyes whereas stage 1 was present in 12 eyes as well. CONCLUSIONS: The diffuse lamellar keratitis is a rare complication. The patients reached good final visual acuity without correction. Slight form of this complication prevailed.