[Whether laser corneal refractive surgery combined with presbyopia correction technology could treat presbyopia].

Presbyopia refers to a phenomenon in which the ability of the eye to accommodate is insufficient to meet the daily demand for proximity due to age. In modern society, more and more patients over 40 years old want to solve visual problems caused by presbyopia and refractive errors, which poses new challenges for clinical laser corneal refractive surgery, and a variety of combined presbyopia correction technologies and programs have emerged. However, whether laser corneal refractive surgery combined with presbyopia correction technology could treat presbyopia deserves clinical attention. Based on the mechanism of laser corneal refractive surgery and various presbyopia correction techniques, this article deeply analyzes the purpose and effect of laser corneal refractive surgery combined with presbyopia correction technology. It is proposed that this surgical treatment could only play a role in correcting presbyopia at present and should be performed accordingly.

[Explore the safety and efficiency of mild myopia retention in patients with myopia and presbyopia].

Objective: To explore the corrective effects of a personalized corneal refractive surgery design that retains mild myopia in patients over 40 years old with refractive errors and presbyopia. Methods: A retrospective case series study was conducted, including 60 patients (120 eyes) over 40 years old who underwent corneal refractive surgery at Peking Union Medical College Hospital l from January 2023 to December 2023. The patients were divided into two groups based on their preference: Group A (retained mild myopia) and Group B (fully corrected), with 30 patients (60 eyes) in each group. Preoperative and postoperative visual acuity, subjective refraction, slit-lamp examination, corneal topography, and intraocular pressure were assessed at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. The effectiveness and safety indices were calculated based on visual acuity before and after surgery. The National Eye Institute Refractive Quality of Life questionnaire was used to evaluate patient satisfaction and postoperative visual symptoms. Results: There were no significant differences in preoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), corneal thickness, and intraocular pressure between the two groups (all P>0.05). At the final follow-up, the proportions of eyes with UDVA≥0.8 and≥1.0 were 93.3% (56/60) and 60.0% (36/60) in Group A, and 100% (60/60) and 83.3% (50/60) in Group B, respectively. The SE was significantly different between Group A [(-0.35±0.52) D] and Group B [(-0.07±0.55) D] (P<0.05). Near visual acuity was better in Group A than in Group B (P<0.05). The effectiveness indices were 0.96±0.23 and 0.99±0.12, and the safety indices were 1.02±0.11 and 1.02±0.07 for Groups A and B, respectively. Both groups had high overall satisfaction, but Group A had higher scores for near vision, reading, and computer screen viewing. Conclusion: The personalized corneal refractive surgery design that retains mild myopia provides good corrective effects for patients over 40 years old with refractive errors, improving patient satisfaction and quality of life.

[Chinese expert consensus on the perioperative medication in laser corneal refractive surgery (2024)].

With the increasing incidence of myopia year by year and the continuous progress of various treatment techniques, laser corneal refractive surgery has become one of the important ways to correct refractive errors. The rational drug use in the perioperative period is important for the success of surgery and reduction of complications. In 2019, based on the development of laser corneal refractive surgery in China, experts from the Refractive Surgery Experts Group of Ocular Microcirculation Branch of Chinese Society of Microcirculation and the Ophthalmology Branch in the Chinese Medical Association formed the "Chinese Expert Consensus on the Perioperative Medication in Laser Corneal Refractive Surgery (2019)". To further promote the expansion of new clinical technologies and surgical methods, and to improve surgical efficacy, the Refractive Surgery Experts Group of Ocular Microcirculation Branch of Chinese Society of Microcirculation, according to the latest domestic and foreign research results, has recently updated the consensus after a collective discussion.

[Accuracy comparison of total keratometry and standard keratometry in intraocular lens power calculations for post-corneal refractive surgery cataract patients].

Objective: To compare the accuracy of intraocular lens (IOL) power calculations using total keratometry (TK) versus standard keratometry (K) in post-corneal refractive surgery cataract patients. Methods: This retrospective case series study included 30 patients (36 eyes) with a history of laser corneal refractive surgery who underwent cataract extraction and IOL implantation at Qingdao Eye Hospital, Affiliated to Shandong First Medical University, from September 2022 to December 2023. The cohort comprised 16 males and 14 females, with an average age of (53.6±8.1) years. IOL power was calculated using the K-based Haigis-L and Barrett True-K formulas, as well as the TK-based Haigis and Barrett Universal Ⅱ formulas. Postoperative objective refraction was performed to obtain the actual refractive status of the operated eyes. The refractive prediction error (RPE) was defined as the difference between the actual spherical equivalent and the predicted refraction. The absolute value of the RPE was taken as the refractive absolute error (RAE). Differences in errors calculated by the four formulas were compared. Results: TK showed good consistency with K, with TK being on average 0.50 D lower than K. Analysis of variance revealed statistically significant differences in RPE among the four formulas (P<0.001). The RPE for the TK-based Haigis formula was (0.17±0.09) D, and for the Barrett Universal Ⅱ formula, it was (0.21±0.11) D, both significantly better than the K-based Haigis-L formula (-0.61±0.12) D and Barrett True-K formula (-0.57±0.11) D (all P<0.001). The percentage of eyes with postoperative RPE<±1.00 D was higher for the TK-based Haigis (92%, 33 eyes) and Barrett Universal Ⅱ (86%, 31 eyes) formulas compared to the TK-based Barrett True-K (75%, 27 eyes) and Haigis-L formulas (67%, 24 eyes), with statistically significant differences (P<0.05). Conclusions: Compared with K, TK improves the accuracy of IOL power calculation in post-corneal refractive surgery patients. Both the TK-based Barrett Universal Ⅱ and Haigis formulas demonstrate high accuracy.

Pediatric refractive surgery: current opinion in ophthalmology.

PURPOSE OF REVIEW: Pediatric refractive surgery has been growing at a steady pace since its introduction in the early 1980 s. This article will review common laser refractive surgeries performed on pediatric patients along with controversies regarding the practice. RECENT FINDINGS: Pediatric refractive surgery is reserved for a small population of children who fail amblyopic treatment due to high anisometropic refractive errors. Publications over the years have treated these children with various types of laser refractive surgery. SUMMARY: Laser pediatric refractive surgery appears to be well tolerated and effective for the population of children that need it. It provides an alternative for anisometropic amblyopia treatment for children who would have otherwise not been able to improve their vision.

Unexpectedly high corneal flap thickness and ectasia after mechanical LASIK / Espessura inesperadamente alta do flap corneano e ectasia após LASIK mecânico

ABSTRACT LASIK is a refractive surgical procedure in which a corneal flap is created to expose the corneal stromal bed. Preoperative estimation of corneal flap thickness is necessary to calculate the percentage tissue altered in LASIK, an important quantitative risk factor for ectasia. The objective of this study was to assess flap thickness and calculate percentage tissue altered to check if unexpectedly thicker flaps and higher percentage tissue altered could pose as risk factors of ectasia. Four subjects (eight eyes) were submitted to mechanical LASIK in 2009 and 2010. Pre and postoperative clinical and tomographic data were reviewed. Mean preoperative estimated percentage tissue altered was 39.18±1.31%, which was borderline for increased ectasia risk when considering the limit of 40%. However, when considering the postoperatively measured flap thickness, the actual mean percentage tissue altered turned out to be 45.17 ± 4.13%, which was significantly higher than predicted preoperatively (p=0.002). Unexpectedly higher postoperative percentage tissue altered may be responsible for corneal ectasia after mechanical LASIK.

RESUMO A LASIK é um procedimento cirúrgico refrativo, no qual um retalho corneano é criado para expor o leito estromal corneano. A estimativa pré-operatória da espessura do retalho corneano é necessária para calcular o percentual de tecido alterado no LASIK, um importante fator de risco quantitativo para ectasia. O objetivo deste estudo foi avaliar a espessura do retalho e calcular o percentual de tecido alterado para verificar se retalhos inesperadamente mais espessos e percentuais de tecido alterado mais altos poderiam representar fatores de risco de ectasia. Quatro indivíduos (oito olhos) foram submetidos à LASIK mecânica em 2009 e 2010. Dados clínicos e tomográficos pré e pós-operatórios foram revisados. A média de percentual de tecido alterado pré-operatória estimada foi de 39,18±1,31%, limítrofe para risco aumentado de ectasia quando considerado o limite de 40%. No entanto, ao considerar a espessura do retalho medida no pós-operatório, o percentual de tecido alterado médio real foi de 45,17±4,13%, ou seja, significativamente maior do que o previsto no pré-operatório (p=0,002). O percentual de tecido alterado pós-operatóriao inesperadamente mais alto pode ser responsável pela ectasia da córnea após LASIK mecânico.

Corneal Collagen Crosslinking (CXL) for Corneal Ectasia after Small Incision Lenticule Extraction (SMILE). / Korneales Kollagen-Crosslinking (CXL) bei Hornhautektasie nach SMILE (Small Incision Lenticule Extraction).

With an estimated incidence of 0.011%, the SMILE procedure seems to have the lowest risk of postoperative keratectasia among contemporary keratorefractive procedures. Nevertheless, due to the novelty of the procedure as well as the lack of data, no clear superiority over femto-LASIK or PRK can be stated at this time. In this respect, application of the identical tomographic screening criteria previously developed for excimer-based procedures is of paramount importance to minimize the risk of corneal ectasia. As an adjunct to conventional corneal tomography, newer imaging modalities such as OCT-based epithelial mapping should be used for preoperative screening before keratorefractive surgery. Corneal crosslinking is an established treatment modality for post-SMILE keratectasia, which promises high success rates especially in early stages. The present case report illustrates these diagnostic and therapeutic considerations.

Changes in Retinal Vessel Flow after Small Incision Lenticule Extraction.

Objective: In order to analyze changes in retinal vessel flow after small incision lenticule extraction (SMILE). Methods: A total of 32 patients (62 eyes) who underwent SMILE were enrolled in this prospective study. Optical parameters, including vessel density (VD), and perfusion density (PD) of foveal, parafoveal, and perifoveal regions, respectively, were measured before surgery and at 1 day, 1 week, 1 month, and 3 months postoperation. Preoperative parameters and surgical parameters were recorded. Results: Significant decreases in VD and PD on postoperative day 1 were detected in all quadrants, both in 3 mm and in 6 mm regions (P < 0.001). One month after surgery, VD returned to preoperative levels. None of the preoperative and surgical parameters were significantly correlated with the VD and PD fluctuations (all P > 0.05). Conclusion. VD may decrease significantly with regional disparity 1 day after SMILE while recovering at 1 month. Elevation of intraocular pressure due to suction may account for such changes.

Alteraciones estructurales y funcionales en pacientes con ambliopía / Structural and Functional Alterations in Patients with Amblyopia

Objetivo: Determinar los resultados motores post cirugía refractiva corneal con láser de excímero en pacientes miopes con o sin astigmatismo asociado. Método: Se realizó un estudio preexperimental del tipo antes y después, en el que fueron incluidos 81 pacientes (162 ojos) tratados con LASEK-MMC (65 pacientes) o PRK-MMC (16 pacientes) seguidos por tres meses. Se les realizó un examen oftalmológico completo y se evaluaron las siguientes variables: punto próximo de convergencia, la amplitud de convergencia, divergencia y el alineamiento ocular precirugía y poscirugía. Resultados: Con la cirugía se observó un incremento significativo del punto próximo de convergencia (LASEK-MMC: p = 0,000 y PRK-MMC: p = 0,021). La amplitud de convergencia de cerca y de lejos, así como la amplitud de divergencia tendieron a disminuir, pero la diferencia no fue significativa (p > 0,05). Aumentó el porcentaje de pacientes con exodesviaciones de cerca, después de la cirugía LASEK-MMC (26,2 por ciento → 60,0 por ciento, p = 0,000) y de la PRK-MMC (18,8 por ciento → 81,3 por ciento, p = 0,000), y predominaron las heteroforias pequeñas en ambos casos (LASEK-MMC: 52,3 por ciento y PRK-MMC: 75,0 por ciento). Conclusiones: Con la cirugía fotoablativa con láser, aumentaron las exodesviaciones en el posoperatorio, pero se trató fundamentalmente de heteroforias pequeñas, aunque un número reducido de pacientes desarrolló nuevas exodesviaciones(AU)

Objective: To determine the motor results after corneal refractive surgery with excimer laser in myopic patients with or without associated astigmatism. Method: A pre-experimental study of the before and after type was carried out, in 81 patients (162 eyes) treated with LASEK-MMC (65 patients) or PRK-MMC (16 patients) followed up for three months. A complete ophthalmological examination was performed and the variables were evaluated near point of convergence, amplitude of convergence, divergence, and pre-surgery and postsurgery ocular alignment. Results: A significant increase in the near point of convergence was observed with surgery (LASEK-MMC: p = 0.000 and PRK-MMC: p = 0.021). The amplitude of convergence near and far, as well as the amplitude of divergence tended to decrease, but the difference was not significant (p > 0.05). The percentage of patients with near exodeviations increased after LASEK-MMC surgery (26.2 percent → 60.0 percent, p = 0.000) and PRK-MMC (18.8 percent → 81.3 percent, p = 0.000), and small heterophoria predominated in both cases (LASEK-MMC: 52.3 percent and PRK-MMC: 75.0 percent). Conclusions: The laser photoablative surgery increased postoperative exodeviations, but they were mainly small heterophoria, although a small number of patients developed new exodeviations(AU)

Computational study for temperature distribution in ArF excimer laser corneal refractive surgeries using different beam delivery techniques.

Refractive errors are the most common causes of vision impairment worldwide and laser refractive surgery is one of the most frequently performed ocular surgeries. Clinical studies have reported that approximately 10.5% of patients need an additional procedure after the surgery. The major complications of laser surgery are over/under correction and dry eye. An increase in temperature may be a cause for these complications. The purpose of this study was to estimate the increase in temperature during laser refractive surgery and its relationship with the complications observed for different surgical techniques. In this paper, a finite element model was applied to investigate the temperature distribution of the cornea when subjected to ArF excimer laser at a single spot using various beam delivery systems (broad beam, scanning slit, and flying spot). The Pennes bio-heat equation was used to predict the temperature values at different laser pulse energies and frequencies. The maximum temperature increase by ArF laser ([Formula: see text] frequency and [Formula: see text] pulse energy) at a single spot was [Formula: see text] for [Formula: see text] diopter correction ([Formula: see text] of ablation of corneal stroma) using broad beam, scanning slit, and flying spot beam delivery approaches respectively. The peak temperature due to a single pulse was estimated to be [Formula: see text]. Although the peak temperature (sufficient energy to break intermolecular bonds) exists for a very short time ([Formula: see text]) compared to the thermal relaxation time ([Formula: see text]), there is some thermal energy exchange between corneal tissues during a laser refractive surgery. Heating may cause collagen denaturation, collagen shrinkage, and more evaporation and hence proposed to be a risk factor for over/under correction and dry eye.

Assessment of the correlation of the tear breakup time with quality of vision and dry eye symptoms after SMILE surgery.

PURPOSE: It is well reported that dry eye symptoms can increase after many refractive surgery procedures. This study aims to provide a clinical understanding of the correlation of fluorescein tear film breakup time (FTBUT) with quality of vision (QoV) and dry eye symptoms following small incision lenticule extraction surgery (SMILE). METHODS: Patients electing to have SMILE surgery were subdivided into 2 groups: Group 1 included short preoperative FTBUTs of 3 to 6 seconds (s); Group 2 included long FTBUTs of ≥ 8 s. Uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction, FTBUT, QoV and Ocular Surface Disease Index (OSDI) questionnaires were recorded 1 and 6 months postoperatively. RESULTS: Thirty-nine subjects were included in each group. There was no significant difference in visual outcomes between the 2 groups at both the 1- and 6-month postoperative assessments. FTBUT remained significantly lower in group 1. Oxford staining was initially higher for group 1 at 1 month (P = 0.007), but there was no significant difference at 6 months (P = 0.180). There was no significant difference in QoV or OSDI scores between the 2 groups at both postoperative visits. CONCLUSIONS: Low preoperative FTBUT (3-6 s) does not appear to negatively affect postoperative visual outcomes or results in a greater likelihood of dry eye symptoms and poor ocular surface compared to eyes with a longer preoperative FTBUT. These results suggest that a low preoperative FTBUT does not necessarily increase the likelihood of poor visual acuity, dry eyes symptoms, or poor ocular surface outcomes following SMILE surgery.

Cirugía facorrefractiva en la alta miopía y sus complicaciones / Phaco-refractive surgery in high myopia and its complications

La miopía es un grave problema de salud pública por su alta y creciente prevalencia en distintas áreas geográficas. La cirugía facorrefractiva consiste en la extracción del contenido transparente o esclerosado del cristalino y el implante de una lente intraocular, con el objetivo posoperatorio de alcanzar o acercarse a la emetropía. Ha demostrado un resultado predecible y estable en el tiempo, pero no está exenta de complicaciones. Se presenta un paciente de 44 años de edad con antecedentes de oftalmológicos de miopía elevada, glaucoma secundario y cirugía facorrefractiva en ambos ojos, refracción dinámica de -3,50-100 x 200 con agudeza visual mejor corregida de 0,8 por cartilla de Snellen en el ojo derecho y -5,25 -1,25 x 1600 con agudeza visual mejor corregida de 0,6 en el ojo izquierdo. En el examen biomicroscópico se observó afaquia quirúrgica, opacidad de la cápsula posterior con capsulotomía láser central amplia y presencia de vítreo en la cámara anterior en ambos ojos con cifras de tensión ocular elevadas. Se realizó implante secundario de lente intraocular en ambos ojos. La refracción dinámica a los 3 meses fue para el ojo derecho de: -0,50 -0,50 x 400 con agudeza visual mejor corregida de 0,9 por cartilla de Snellen y para el ojo izquierdo de: -1,00 -0,75 x 1600 con agudeza visual mejor corregida de 0,6 por cartilla de Snellen. A los dos años presentó desprendimiento de retina subclínico en el ojo derecho, que fue tratado con terapia láser, y daño glaucomatoso en el ojo izquierdo. Se le realizó trabeculectomía, trabeculoplastia selectiva láser y posteriormente implante de drenaje valvulado en el ojo izquierdo(AU)

Myopia is a serious public health problem, due to its high and increasing prevalence in various geographic regions. Phaco-refractive surgery consists in extraction of the clear or sclerosed content of the crystalline lens and implantation of an intraocular lens with the postoperative objective of achieving or approaching emmetropia. The procedure has shown to obtain predictable results stable in time, but it is not exempt from complications. A case is presented of a male 44-year-old patient with an ophthalmologic history of high myopia, secondary glaucoma and phaco-refractive surgery in both eyes, dynamic refraction of -3.50-100 x 200 with best corrected visual acuity of 0.8 on the Snellen chart in the right eye and -5.25 -1.25 x 1600 with best corrected visual acuity of 0.6 in the left eye. Biomicroscopic examination found surgical aphakia, posterior capsule opacity with large central laser capsulotomy, presence of vitreous in the anterior chamber of both eyes and high ocular pressure values. Secondary intraocular lens implantation was performed in both eyes. Dynamic refraction at three months was -0.50 -0.50 x 400 for the right eye with best corrected visual acuity of 0.9 on the Snellen chart, and -1.00 -0.75 x 1600 for the left eye with best corrected visual acuity of 0.6 on the Snellen chart. At two years the patient experienced subclinical retinal detachment in the right eye, which was treated with laser therapy, and glaucomatous damage in the left eye, for which the treatment indicated was trabeculectomy, selective laser trabeculoplasty, and then valved drainage implantation in the left eye(AU)

Repeatability and comparability of the Galilei-G4 and Cassini in measuring corneal power and astigmatism in normal and post-refractive surgery eyes.

To assess the repeatability and comparability of the Galilei G4 versus the Cassini topographer in post-refractive eyes and in normal eyes, including older patients representative of an initial cataract evaluation. Simulated keratometric (simK), total corneal and posterior corneal power and astigmatism were evaluated in both post-refractive and normal eyes. Repeatability was measured by calculating within-subject standard deviation (Sw), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Vector analyses and Bland-Altman plots were employed to assess agreement between devices. We studied 32 subjects with a history of refractive surgery and 32 subjects without a history of refractive surgery undergoing cataract surgery. The mean age was 55 ± 18.5 years and the age range was 21.5-91.5 years. In non-refractive and post-refractive eyes, the ICC was > 0.9 (P < 0.001) for all corneal powers and for simK and total corneal astigmatism for both analyzers. The ICC for posterior corneal astigmatism magnitude using the Galilei was 0.62 and 0.67 and for the Cassini 0.55 and 0.38 in normal and post-refractive eyes, respectively. In both post-refractive and normal eyes, the Galilei G4 and Cassini analyzers have high repeatability in simK, total, and posterior corneal power and low repeatability for posterior corneal astigmatism.

Evaluation of postoperative refractive error correction after cataract surgery.

Suboptimal cataract surgery outcomes remain a challenge in most developing countries. In Ghana, about 2 million people have been reported to be blind due to cataract with about 20% new cases being recorded yearly. The aim of this study was to evaluate postoperative correction of refractive errors after cataract surgery in a selected eye hospital in Ashanti Region, Ghana. This was a retrospective study where medical records of patients (aged 40-100) who reported to an eye hospital in Ghana from 2013-2018 were reviewed. Included in the study were patients aged ≥40 years and patients with complete records. Data on patient demographics, type of surgery, intra-ocular lens (PCIOL) power, availability of biometry, postoperative refraction outcomes, pre- and postoperative visual acuity were analyzed. Data of two hundred and thirteen eyes of 190 patients who met the inclusion criteria were analyzed. Descriptive analysis and Chi-square test were carried out to determine the mean, median, standard deviation and relevant associations. The mean ± SD age was 67.21±12.2 years (51.2% were females). Small Incision Cataract Surgery (99.5%) with 100% IOL implants was the main cataract surgery procedure in this study. Pre-operative biometry was performed for 38.9% of all patients on their first eye surgery and 41.5% for second eye surgeries. About 71% eyes in this study were blind (presenting VA<3/60) before surgery; 40.4% had post-operative VA <3/60. Pre-existing ocular comorbidities discovered post- surgery, attributed to suboptimal visual outcomes. More than half (55.3%) of patients did not undergo postoperative refraction due to loss to follow-up. Year of surgery (p = .017), follow up visits< 2months (p < .0001) and discovered comorbidity post-surgery (p = .035) were the factors significantly associated with postoperative refraction. Myopia and compound myopic astigmatism were the dominant refractive error outcomes. The timing of post-operative refraction had a significant effect on postoperative refraction done. These findings indicate a clinically meaningful significance between completion of postoperative care and postoperative refraction done. Consequently, with settings in most developing countries, where less biometry is done, it is appropriate that post-operative refractive services are encouraged and done earlier to enhance the patients' expectations while increasing cataract surgery patronage.

Fórmula Barrett True K en pacientes con catarata operados de cirugía refractiva corneal / The Barrett True-K formula in cataract patients undergoing corneal refractive surgery

Objetivo: Determinar los resultados refractivos en pacientes operados de catarata con cirugía refractiva corneal, según el cálculo del poder dióptrico de la lente intraocular con la fórmula Barrett True K. Métodos: Se realizó un estudio pre-experimental, del tipo antes y después, en el cual fueron incluidos 18 pacientes (31 ojos). En ellos se analizaron variables demográficas y clínicas. La principal variable de salida fue la predictibilidad del componente esférico ± 0,50 D, ± 1,0 D según la longitud axial. Resultados: Fueron estudiados pacientes con un promedio de edad de 59,4 años, predominantemente del sexo femenino (66,7 por ciento). El 77,4 por ciento fue operado con queratotomía radial. Con la cirugía de catarata se produjo una mejora ostensible de la agudeza visual no corregida (mediana preoperatoria: 0,12 y mediana posoperatoria: 0,60). Solo el 9,7 por ciento de los ojos analizados presentó una agudeza visual sin corregir de 20/20 y el 90,3 por ciento de 20/40 o más. La cantidad de ojos con un equivalente esférico de ± 0,50 disminuyó en la medida en que aumentó la longitud axial (corta: 100 por ciento; normal: 57,1 por ciento; larga: 22,7 por ciento), no así la predictibilidad del componente esférico de ± 0,50, que aumentó (corta: 50,0 por ciento; normal: 57,1 por ciento; larga: 63,6 por ciento). Conclusiones: La fórmula Barrett True K resulta útil para el cálculo de la lente intraocular en pacientes operados de catarata y cirugía refractiva corneal previa(AU)

Objective: Determine refractive outcomes in patients undergoing cataract corneal refractive surgery based on intraocular lens dioptric power calculation with the Barrett True-K formula. Methods: A pre-experimental before/after study was conducted of 18 patients (31 eyes). Demographic and clinical variables were analyzed. The main output variable was spherical component predictability ± 0.50 D, ± 1.0 D according to axial length. Results: Mean age was 59.4 years; female sex prevailed (66.7 percent). Of the patients studied, 77.4 percent underwent radial keratotomy. Cataract surgery led to notable uncorrected visual acuity improvement (preoperative mean: 0.12; postoperative mean: 0.60). Only 9.7 percent of the eyes examined had an uncorrected visual acuity of 20/20, whereas 90.3 percent had 20/40 or more. The number of eyes with a spherical equivalent of ± 0.50 fell as axial length rose (near: 100 percent; normal: 57.1 percent; far: 22.7 percent), unlike ± 0.50 spherical component predictability, which rose from near: 50.0 percent; normal: 57.1 percent; far: 63.6 percent. Conclusions: The Barrett True-K formula is useful for intraocular lens calculation in patients undergoing previous cataract and corneal refractive surgery(AU)

Information sources for patients undergoing corneal refractive surgery: results from a cross-sectional patient survey from a single private center in Pola​nd.

PURPOSE: To identify the information sources for patients undergoing laser vision correction. METHODS: Individuals who underwent corneal refractive surgery at a private practice from December 2017 to August 2018 and agreed to complete an anonymous questionnaire were included. The manifest refraction and surgical method was recorded and correlated with the questionnaire results. RESULTS: Data collected from 126 patients (mean age, 32.8 ± 8.6 years; 55.6% women) were analyzed. Of 121 patients, 120 (99.2%) identified the Internet as a source for information on refractive surgery, and 71 of 119 (59.7%) noted that the clinic's website influenced their choice of clinic. Patients with high myopia more commonly used contact lenses and had considered undergoing refractive surgery for a longer time compared with patients with other refractive errors (P < 0.01 and P < 0.01, resp.). Patients with hyperopia were less likely to know their own refractive error (P = 0.02). CONCLUSIONS: In this patient cohort, the Internet was the main source of information for those undergoing refractive surgery.

A new trifocal corneal inlay for presbyopia.

Corneal inlays (CIs) are the most recent surgical procedure for the treatment of presbyopia in patients who want complete independence from the use of glasses or contact lenses. Although refractive surgery in presbyopic patients is mostly performed in combination with cataract surgery, when the implantation of an intraocular lens is not necessary, the option of CIs has the advantage of being minimally invasive. Current designs of CIs are, either: small aperture devices, or refractive devices, however, both methods do not have good performance simultaneously at intermediate and near distances in eyes that are unable to accommodate. In the present study, we propose the first design of a trifocal CI, allowing good vision, at the same time, at far, intermediate and near vision in presbyopic eyes. We first demonstrate the good performance of the new inlay in comparison with a commercially available CI by using optical design software. We next confirm experimentally the image forming capabilities of our proposal employing an adaptive optics based optical simulator. This new design also has a number of parameters that can be varied to make personalized trifocal CI, opening up a new avenue for the treatment of presbyopia.

Comparación entre las mediciones biométricas del IOL Master 500 y el Pentacam AXL en la biometría ocular / Comparison of biometric measurements taken with IOL Master 500 and Pentacam AXL for ocular biometry

Objetivo: Comparar las mediciones biométricas realizadas con el IOL Master 500 y el Pentacam AXL. Métodos: Se realizó un estudio transversal en 99 ojos de 99 pacientes miopes con criterio de cirugía fotoablativa, atendidos en el período de enero del año 2019 a enero de 2020, en el Servicio de Cirugía Refractiva del Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Las variables estudiadas fueron edad, sexo, equivalente esférico y características biométricas preoperatorias (longitud axial, profundidad de la cámara anterior y queratometrías), así como su relación, aportadas automáticamente por el IOL Master 500 y el Pentacam AXL para evitar los factores dependientes del operador. El análisis estadístico se realizó con la Prueba t para datos pareados, utilizando una significación del 95 por ciento. Una diferencia con un valor de p < 0,05 fue considerado estadísticamente significativo. Resultados: El 60,61 por ciento de los pacientes eran de sexo femenino y el 39,39 por ciento del masculino, con una edad promedio de 25,67 ± 4,30 años. Se analizaron 51 ojos derechos y 48 izquierdos. El equivalente esférico medio fue de -3,30 ± 1,53 dioptrías. No hubo diferencia estadísticamente significativa entre los valores biométricos (longitud axial, profundidad de la cámara anterior y queratometrías) obtenidos con el IOL Master 500, en comparación con los del Pentacam-AXL (p > 0,05). Conclusión: Las mediciones biométricas (longitud axial, profundidad de la cámara anterior y queratometrías) obtenidas con el IOL Master 500 y el Pentacam-AXL son similares(AU)

Objective: Compare biometric measurements taken with IOL Master 500 and Pentacam AXL. Methods: A cross-sectional study was conducted of 99 eyes of 99 myopic patients with indication of photoablative surgery attending the Refractive Surgery Service at Ramón Pando Ferrer Cuban Institute of Ophthalmology from January 2019 to January 2020. The variables analyzed were age, sex, spherical equivalent and preoperative biometric characteristics (axial length, anterior chamber depth and keratometries) and the relationship to one another, automatically supplied by IOL Master 500 and Pentacam AXL to avoid operator-dependent factors. Statistical analysis was based on the paired T-test with a significance level of 95%. A difference with a p-value < 0.05 was considered to be statistically significant. Results: Of the patients studied, 60.61 percent were female and 39.39 percent were male; mean age was 25.67± 4.30 years. A total 51 right eyes and 48 left eyes were analyzed. Mean spherical equivalent was -3.30 ± 1.53 diopters. No statistically significant difference was found between the biometric values (axial length, anterior chamber depth and keratometries) obtained with IOL Master 500 versus Pentacam AXL (p > 0.05). Conclusion: Similar biometric measurements (axial length, anterior chamber depth and keratometries) are obtained with IOL Master 500 and Pentacam AXL(AU)