Rasch development and validation of the “Medellín Dry Eye Inventory” (ME·Dry), an instrument to measure multidimensional quality of life compromise in patients with dry eye disease

Purpose: Dry eye disease (DED) is a common condition that affects the quality of life. There is a great need for better?developed scales that comply with Rasch model requirements. Methods: Prospective study including patients with DED. A series of focus groups were performed to determine the best items to be included. A Rasch modeling methodology was used to validate the Medellín Dry Eye Inventory (ME·Dry). After iterative analysis and scale modification, a final version of the scale was attained which complied with the Rasch analysis expectations. Correlation between the different subscales of the ME·Dry and the Ocular Surface Disease Index (OSDI) was evaluated through Spearman correlation. Results: A total of 166 patients with DED were included. Rasch modeling demonstrated an excellent behavior for the ME·Dry, including four subscales: Symptoms, Triggers, Activity Limitation, and Emotional Compromise. Infit and Outfit parameters were all between 0.50 and 1.50, with excellent category utilization. Person and item separation and reliability were excellent for all subscales. There was a need for a category collapsing for the Emotional Compromise subscale. There was a strong correlation between the different subscales of the ME·Dry except for the Emotional Compromise subscale, which seems to be independent. Conclusion: The ME·Dry is a reliable scale, complying with the Rasch model expectations, that allows for a reliable measurement of quality of life compromise in patients with DED. Emotional compromise secondary to DED does not seem to correlate with disease severity as assessed by the other quality?of?life subscales.

Determination of the repeatability of corneal densitometry as measured with a Scheimpflug camera device in refractive surgery candidates

Purpose: Corneal densitometry analysis provides an objective measurement of corneal transparency in patients undergoing photorefractive keratectomy (PRK). To date, no study that focuses on determining the reliability and smallest real difference (SRD), specifically in PRK candidates, has been published. Methods: The study was conducted at Clínica de Oftalmología Sandiego, Medellín, Colombia. This was a prospective and analytical study. Refractive surgery candidates underwent Pentacam measurements twice with five minutes of difference. Repeatability of measurements was evaluated for every area using Wilcoxon signed?rank test, Spearman’s rank?order correlation, and the intraclass correlation coefficient, followed by a within?subjects factor (Sw) finishing with a determination of the SRD for all areas. Bland–Altman plots were created and analyzed. Results: A total of 110 eyes were included. The mean total densitometry was 18.67 ± 1.56 grayscale units (GSU) and 18.65 ± 1.49 GSU for the first and second measurements, respectively. Wilcoxon was non?significant (P > 0.05) while the intraclass correlation coefficient demonstrated an excellent agreement. SRD ranged from 0.21 GSU (posterior × 6–10 mm) to 1.79 GSU (total × 10–12 mm). Anterior depths and 10–12 mm annulus had consistently more variability and greater (worse) SRD. The 10–12 mm annulus showed great dispersion on the Bland–Altman plots. Conclusion: Corneal densitometry has an excellent repeatability in refractive surgery candidates for areas below 10 mm. Any densitometry change ?1.0 GSU in areas under 10 mm should be considered as well above measurement noise and corresponding to a real change in measured parameters. The 10–12 mm area does not seem to be reliable enough in refractive surgery candidates to warrant surveillance after corneal?based surgery

Lente multifocal de tres piezas con captura de la óptica, como manejo de ruptura de la cápsula posterior en paciente sometida a cirugía facorrefractiva / Three-piece multifocal intraocular lens with optic capture as management of posterior capsule rupture in a patient undergoing refractive lens exchange

Se presenta el caso de una paciente sometida a cirugía facorrefractiva que sufre una ruptura de la cápsula posterior en la cirugía del primer ojo. Ante la imposibilidad de usar un lente trifocal de una pieza como inicialmente se tenía planteado, se realiza implante de lente multifocal de tres piezas en el sulcus con captura pupilar. Se reportan las imágenes de Scheimpflug y de retroiluminación del lente de tres piezas de un ojo y el lente de una pieza del ojo contralatera

We present the case of a female patient who suffered a posterior capsule rupture while undergoing refractive lens exchange. In view of the impossibility of using a single piece intraocular lens as was initially planned, a three-piece multifocal intraocular lens with an optic capture was positioned. Scheimpflug and retro-illumination images are presented.

Mejoría de la calidad visual, corneal y refractiva en queratocono por medio del protocolo de Atenas / Improvement of visual, corneal, and refractive quality in keratoconus through the Athens protocol

Se presenta el caso de un paciente con queratocono, con distorsión corneal moderada, quien es sometido a cirugía PRK guiada por topografía con crosslinking (protocolo de Atenas), con un excelente resultado anatómico y funcional. Se reportan las imágenes de tomografía de Scheimpflug y la simulación de calidad visual basada en aberrometría Hartmann-Shack.

This article presents the case of a keratoconus patient with moderate corneal distortion who underwent simultaneous topography-guided PRK and corneal crosslinking (Athens protocol), achieving an excellent anatomical and visual improvement. Scheimpflug tomography and Harmann-Shack aberrometry-based visual simulations are presented.

The Pentacam® AXL Wave provides a reliable wavefront-based objective refraction when compared to manifest subjective refraction: A prospective study

Purpose: Accurate refraction is arguably the most important parameter for a successful laser vision correction surgery and is based on a combination of manifest and cycloplegic refraction. Wavefront?based objective refraction may be useful in the evaluation of patients. So far, the reliability of objective refraction as measured using the Pentacam® AXL Wave has not been published in the literature. Methods: This was a prospective study including a total of 168 eyes belonging to 84 young non?presbyopic patients evaluated for refractive surgery. Pentacam® AXL Wave full sequence was taken for all patients. Then, a clinician who was unaware of the objective refraction results performed a full physical examination, including manifest refraction starting from an autorefractometer value. All refraction values were transferred to astigmatic power vectors as per the Thibos method. Reliability of the different vectors and a unifying blur value were compared using Spearman correlation, Bland–Altman plot, and intraclass correlation coefficient. Results: The mean age was 28.8 ± 5.4 years, with a female preponderance (60.7%). The correlation between both eyes was high. The difference in M vector between subjective and objective refraction was 0.16 D, while the difference was 0.04 and 0.01 D for the J0 and J45 vectors, respectively. Paired samples Student t was non?significant for all comparisons. Spearman rho correlations were high (0.666–0.924, all P < 0.001). Intraclass correlation coefficients were also high (0.890–0.966). Bland–Altman plots did not demonstrate any systematic errors. Conclusion: Wavefront?based refractive refraction obtained using the Pentacam® AXL Wave is highly agreeable and correlated with measurements obtained by manifest subjective refraction.

Cataratas en pacientes sometidos a implante de lente intraocular fáquico: una ocurrencia muy poco habitual / Cataract in patients undergoing phakic intraocular lens implantation: an uncommon event

Se presenta el caso de dos pacientes con vault anormalmente bajo luego del implante de lentes intraoculares fáquicos. Se reportan las imágenes de Scheimpflug y retroiluminación que han permitido el diagnóstico temprano.

We present the cases of two patients who developed an abnormally low vault and subcapsular anterior cataracts after phakic intraocular lens implantation. Scheimpflug and retroillumination images are reported

Distrofia polimorfa posterior vista por medio de tomografía Scheimpflug y retroiluminación / Posterior polymorphous corneal dystrophy as seen through Scheimpflug tomography and corneal retroilumination

Se presenta el caso de un paciente de género masculino de 31 años de edad, a quien se le diagnosticó distrofia polimorfa posterior, una entidad poco frecuente, secundaria a alteraciones a nivel de la cresta neural. Si bien la mayoría de los pacientes tiene afectación bilateral, no son raros los casos totalmente unilaterales, como el reportado en el presente artículo.

We present the case of a 31-year-old male patient, who was diagnosed with posterior polymorphic dystrophy, a rare hereditary condition of the neural crest-derived. Although most patients have bilateral involvement, totally unilateral cases, such as the one reported in this article, are not rare

La presencia de fluoresceína induce una aleatorización temporal de los datos de cara posterior corneal medidos por un sistema de doble cámara de Scheimpflug ­ Estudio Piloto / Presence of fluorescein induces a temporal aleatorization of posterior corneal data as measured with a double Scheimpflug camera ­ a pilot study

Antecedentes: La medición fidedigna de parámetros tomográficos corneales es de gran importancia para el oftalmólogo general y para el cirujano de córnea, por cuanto permite un mejor diagnóstico y enfoque del paciente evaluado. Se ha visto que la presencia de fluoresceína en superficie ocular aumenta falsamente las paquimetrías según medida del Pentacam pero no se conoce si sucede algo similar con el equipo Galilei. Métodos: Estudio prospectivo, de intervención, aleatorizado, que pretendió evaluar si la presencia de una mezcla comercialmente disponible de fluoresceína induce cambios sobre los parámetros tomográficos tomados con el equipo Galilei G4 en un grupo de voluntarios sanos. Como control se utilizó la instilación de solución salina fisiológica en el ojo contralateral. Resultados: En total se incluyeron 36 ojos pertenecientes a 18 voluntarios sanos ocularmente. En el estado basal no se encontraron cambios en los parámetros tomográficos del grupo control con respecto al grupo intervención. Al minuto y a los cinco minutos de observación, se encontró una dispersión marcada de los datos correspondientes y derivados de la cara posterior corneal. Estos cambios se normalizaron a los 20 y 40 minutos de seguimiento luego de la instilación. Conclusiones: La presencia de fluoresceína sobre la superficie ocular induce cambios artefactuales importantes que pueden llevar a errores diagnósticos. Es recomendable esperar un tiempo prudencial desde la instilación de fluoresceína en el consultorio antes de realizar un estudio tomográfico en el paciente.

Background: Trustable measuring of tomographic parameters is of outmost importance for both the comprehensive ophthalmologist and the corneal surgeon, as it allows for a correct diagnosis of the patient. It has been shown that the presence of fluorescein on the corneal surface artefactually increases pachimetry values when measured with a Pentacam device, but it is unknown whether the same behavior is seen when a Galilei equipment is used. Methods: Prospective, randomized, intervention study, which sought to evaluate if the presence of a commercially available fluorescein mixture induced changes on tomographic parameters as measured by a Galilei G4 equipment on healthy subjects. Instillation of sodium chloride was used as a control. Results: 36 eyes belonging to 18 healthy volunteers were included. Before intervention, there was no diff erence on tomographic data between the intervention and the control groups. At one and fi ve minutes aft er intervention, the fluorescein group exhibited an important dispersion of posterior corneal surface data. These changes subsided at 20 and 40 minutes after fluorescein instillation. Conlusions: The presence of fluorescein on the corneal surface induced a number of important errors in tomographic data.