The Effects of Whole-Corneal and Whole-Eye Higher Order Aberrations on the Discrepancy Between Refractive and Corneal Astigmatism in Otherwise Healthy Candidates for Refractive Surgery.

PURPOSE: To evaluate the effect of different whole-corneal and whole-eye higher order aberrations (HOAs) on levels of axis discrepancy. METHODS: This was a retrospective study including healthy candidates for refractive surgery, with one eye being randomly selected. A total of 360 eyes were included. Whole-corneal and whole-eye HOAs were measured twice with a Pentacam AXL Wave (Oculus Optikgeräte GmbH), and subjective manifest refraction was obtained. Axis discrepancy was defined as the absolute difference between Total Corneal Refractive Power flat keratometry axis and manifest refractive axis. Two multiple linear regression models that sought to explore the effect of HOAs in predicting axis discrepancy while adjusting for corneal and refractive confounders were built. RESULTS: Mean age was 29.1 ± 5.8 years and 63.9% of the patients were women. Mean manifest sphere and cylinder were -3.09 ± 2.36 and -1.45 ± 1.37 diopters (D), respectively. Mean cylinder axis discrepancy was 14.4 ± 14.5°. On multiple linear regression, the only variables significantly associated with axis discrepancy were corneal cylinder and corneal lower order aberrations [F(5,339) = 29.746; P < .001; adjusted R2 = 0.295]. Lower levels of corneal cylinder are by far the main contributor to astigmatism axis mismatch (ß = -1.164). There was not a single HOA, either corneal or ocular, that significantly loaded into any models. CONCLUSIONS: Astigmatism axis mismatch decreases rapidly with increasing levels of corneal astigmatism. Corneal and whole-eye HOAs have no role in astigmatism axis mismatch in healthy candidates for refractive surgery. [J Refract Surg. 2024;40(2):e89-e97.].

Ocular residual astigmatism (ORA) does not seem to correlate with baseline refractive error among refractive surgery candidates.

PURPOSE: Ocular residual astigmatism (ORA) is defined as the difference between refractive astigmatism and anterior corneal astigmatism. A high ORA may be correlated with poorer results in patients undergoing corneal-based laser surgery. Is a high baseline refractive error related to a higher degree of ORA? METHODS: This was a retrospective analytical study including 181 right eyes of an equal number of refractive surgery candidates. Manifest subjective refraction was measured, along with a Pentacam AXL Wave corneal tomography. Via a vector analysis with this methodology, subjective cylinder was translated into the corneal plane and a vectorial subtraction was performed in order to measure ORA. Spearman's rank order test, one-way ANOVA and Chi-square were used to determine whether different levels of baseline refractive error correlate with different levels of ORA. RESULTS: Mean age was 28.33 ± 4.71 years with a female preponderance (65.7%). Mean ORA was 0.74 ± 0.39 D, with 33.1% of eyes having an ORA ≥ 0.90 D. There was not a correlation between ORA and level of myopia (rho = - 0.022; p = 0.764), nor between ORA and spherical equivalent (rho = 0.009; p = 0.903). Refractive astigmatism did not demonstrate to be correlated with ORA level either (rho = 0.078; p = 0.329). One-way ANOVA tests failed to demonstrate an association between different classifications of refractive error and level of ORA. CONCLUSIONS: In the studied population, ORA is not correlated with baseline refractive error. Every patient presenting for possible corneal-based laser refractive surgery should be evaluated for a possible high level of ORA, irrespective of their baseline ametropia level.

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.

Corneal and Whole-Eye Higher Order Aberrations Do Not Correlate With Ocular Residual Astigmatism in Prepresbyopic Refractive Surgery Candidates.

PURPOSE: Ocular residual astigmatism (ORA) is the proportion of manifest astigmatism that is not explained by anterior corneal astigmatism. The role of higher order aberrations (HOAs) in the level of ORA has not been profoundly studied. The purpose of this study was to evaluate the effect of different corneal and whole-eye HOAs on levels of ORA using a multivariate modeling approach. METHODS: This is a retrospective analytical study including a sample of healthy refractive surgery candidates. One eye of every patient was randomly selected. A total of 294 eyes from an equal number of patients were included. Corneal and whole-eye HOAs were measured with a Pentacam AXL Wave, and subjective manifest refraction was taken. Astigmatism values were converted into power vectors and ORA was calculated. The Spearman rank-order correlation was initially used to explore correlation between HOA and ORA. All variables with a P value under 0.10 were included into a multiple linear regression model to explore this correlation adjusting for confounding variables. RESULTS: The mean age was 28.81 ± 5.40 years. Simple bivariate correlation was significant for root mean square (RMS) total, RMS lower order aberrations, RMS HOAs, defocus, and vertical astigmatism. After being included into a multivariate regression model adjusting for confounding variables, the only variable that was significant was RMS total [F (3, 282) = 78.977; P < 0.001; adjusted R 2 = 0.451]. For every µm increase in corneal RMS total, ORA increases by 0.135 diopters. About 45% of variability in ORA can be explained by corneal RMS total, corneal J 0 , and manifest J 0 . No individual HOA correlated with ORA in the multivariate regression model. CONCLUSIONS: ORA increases with general corneal irregularity, especially regular astigmatism. Irregular astigmatism expressed by corneal and whole-eye HOAs does not seem to be a significant contributor of ORA in healthy refractive surgery candidates.

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.

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.

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.

Standardizing the measurement and classification of quality of life using the Keratoconus End-Points Assessment Questionnaire (KEPAQ): the ABCDEF keratoconus classification.

BACKGROUND: Measuring quality of life is of importance in keratoconus. So far, the Keratoconus End-Points Assessment Questionnaire (KEPAQ) is the only keratoconus-specific scale to measure emotional well-being along with functional compromise in this population. Nevertheless, there is still a lack of clarity and standardization as to how KEPAQ scores should be computed and reported. There are also no guidelines for interpretation of classification of quality of life when using this instrument. The purpose of this study is to provide a specific framework on how to grade and classify keratoconus by using the KEPAQ and propose an extension of current classification to encompass subjective compromise. METHODS: A group of patients with a confirmed diagnosis of keratoconus underwent application of the KEPAQ. First, a Rasch modeling was performed to evaluate the psychometric characteristics of both sub-scales of the instrument. Then, a linear transformation was performed to turn data into a more relatable scale ranging from 0 to 100. Finally, by using Tukey's Hinges, scores of the KEPAQ were divided in a 1-to-4 scale, allowing for an easy E&F classification system. RESULTS: A total of 386 applications of the KEPAQ were included. Analysis provided evidence of the KEPAQ being unidimensional, well-fitted to the Rasch Model, and provided adequate interval-level scores. Linear transformation resulted in a user-friendly final score ranging from 0 to 100, where a higher score translates to having a better quality of life. Two methods of easily computing final score, one by hand and the other one by an Excel file, were constructed. An E&F 1-to-4 classification was proposed, which may work well with the current ABCD classification of keratoconus. CONCLUSIONS: The KEPAQ is a psychometrically robust scale, which confidently measures both emotional-related and functional-related quality of life in patients with keratoconus. It can be easily computed, and the results are interpretable and classified in a manner similar to that used in the ABCD keratoconus classification, by adding letters 'E' for emotional and 'F' for functional compromise.

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

Both subscales of the Keratoconus End-Points Assessment Questionnaire have excellent test-retest reliability.

Purpose: The keratoconus end-points assessment questionnaire (KEPAQ) is a disease-specific scale designed to evaluate the quality of life in keratoconus patients and provides the measurement of both functional and emotional compromise in keratoconus. It was previously developed, tested, and validated and now we want to evaluate the test-retest reliability of the KEPAQ, in an effort to contribute evidence on its internal consistency and capability of measuring clinical state with minimal inference of random chance. Methods: This is a prospective analytical study, designed to evaluate the test-retest reliability of the KEPAQ through the repeated application of the questionnaire to a group of clinically stable individuals. A number of patients with a confirmed diagnosis of keratoconus underwent double application of the KEPAQ, seven days apart. Mean KEPAQ score was obtained through Rasch analysis, while test-retest reliability was evaluated through Spearman rank-order correlation and intraclass correlation coefficient. Rasch analysis was performed in JMetrik version 4.1.1 (Psychomeasurement Systems LLC; Charlottesville, VA, USA) in a MacBook Air computer running macOS Catalina version 10.15.2 (Apple Inc.; Cupertino, CA, USA). Results: A total of 100 patients were included. For KEPAQ-E, Spearman correlation was R = 0.963 while ICC was 0.981 (95% confidence interval 0.972-0.987). For KEPAQ-F, Spearman correlation was R = 0.921 while ICC was 0.952 (95% confidence interval 0.929-0.968). Conclusion: The KEPAQ is a robust, well-developed, extremely reliable scale which can be confidently used for clinical and research endeavors.

Early results with the EyeCryl Phakic Toric intraocular lens implantation in keratoconus patients.

Objective: Refractive management in keratoconus is challenging. Although some kinds of phakic intraocular lenses have been studied in keratoconus so far, no study evaluated the results of EyeCryl Phakic Toric intraocular lenses in this kind of patients. Materials and Methods: This is a retrospective chart review study, including all keratoconus patients implanted with an EyeCryl Phakic Toric intraocular lens in at least one of their eyes by an experienced cornea surgeon in Colombia. Follow-up to 6 months after surgery was also included. Results: A total of 20 eyes of 14 patients were included, with an average age of 29.3 ± 4.2 years. Spherical equivalent improved from a pre-surgical value of -10.31 D to +0.09 D at 6 months. 65% of the patients improved at least one line in the best-corrected distance visual acuity. At 6 months, 70% of the patients were within ± 0.50 D of spherical equivalent emmetropia. No complications occurred in any of the patients. Conclusion: EyeCryl Phakic intraocular lenses are an excellent option in keratoconus patients with high refractive error. Abbreviations: KC = Keratoconus, P-IOL = phakic intraocular lenses, ICL = Implantable Collamer Lens, WTW = White to White, SD = standard deviation, ANOVA = an analysis of variance, UDVA = monocular uncorrected distance visual acuity, CDVA = corrected distance visual acuity.

Rasch development and validation of a new faces scale for measuring pain, and its comparison with a gold standard: the Balparda-Herrera Pain Scale.

Aim: Faces pain scales are widely used to measure pain. So far, no faces pain scale has ever been constructed by Rasch modeling. Hence the authors aimed to construct a new scale by this method. Methods: Rasch modeling was used to provide an initial calibration and development of the 'Balparda-Herrera Pain Scale' (BHPS) and this scale was compared with the existing Faces Pain Scale - Revised. The scale was later refined. Results: Both the existing scale and the initial version of the BHPS required category collapsing. Statistical tests demonstrated an excellent concordance between both scales. The final version of the BHPS was found to behave excellently and to be capable of adequately measuring pain. Conclusion: The BHPS provides an excellent instrument for measuring pain in the adult population.

Lay abstract Pain is an unpleasant experience for patients, and it is useful for physicians to try to measure how much pain the patient is experiencing. Some scales used by physicians include faces with different expressions to represent various amounts of pain. Rasch modeling is a mathematical approach to develop better scales. In this study, the researchers performed two surveys in order to develop and improve a new scale for measuring pain: the Balparda­Herrera Pain Scale. They used mathematical and statistical approaches to optimize the scale and to compare with another well-known scale. The authors found that the new scale is very useful for measuring pain.

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

Unilateral Toxic Anterior Segment Syndrome Resulting in Cataract and Urrets-Zavalia Syndrome after Sequential Uneventful Implantation of a Posterior Chamber Phakic Toric Intraocular Lens at Two Different Surgical Facilities: A Series of Unfortunate Events.

BACKGROUND: Phakic Intraocular Lens (P-IOL) implantation is a safe, easy, predictable intervention designed to manage moderate to high refractive errors. Complications are relatively uncommon and include mainly cataract and intraocular pressure spikes. Toxic Anterior Segment Syndrome (TASS) is a rather unusual sterile anterior segment inflammation after uneventful intraocular surgery, extremely rarely reported after P-IOL implantation. Urrets-Zavalia Syndrome (UZS) is also very rarely described after P-IOL. To date, to the best of the authors' knowledge, no article has ever described the simultaneous occurrence of TASS and UZS in a patient after P-IOL implantation. OBJECTIVE: In this article, the authors present the case of a female patient with moderate myopic astigmatism, who underwent sequential P-IOL implantation at two different facilities. The postoperative course of the first eye was uneventful, but she developed complications associated to the intervention in the second eye. MATERIALS: The article describes the case of a young patient who underwent a sequential Phakic Intraocular Lens (P-IOL) implantation at two different institutions. The postoperative course of the first eye (left eye) was uneventful; however, the second eye (right eye) initially developed Toxic Anterior Segment Syndrome (TASS). Although timely and correct management was instituted, upon resolution of TASS, the patient developed Urrets-Zavalia Syndrome, anterior subcapsular cataract, and significant endothelial damage in the same eye. RESULTS: The patient was followed closely and managed accordingly; corneal edema and anterior segment inflammation of the right eye eventually resolved. Nevertheless, an anterior subcapsular cataract and a fixed dilated pupil remained; with normal intraocular pressure (IOP). Specular microscopy confirmed an endothelial cell loss in the TASS eye (right eye). Pupil size showed no reaction to repeated doses of Pilocarpine 2%. A month after surgery, refraction on her right eye was +0.25 + 0.75 × 93, which resulted in a 20/50 vision. CONCLUSIONS: TASS and UZS are both extremely rare complications after uneventful P-IOL implantation, with only a handful of cases having been reported of each of them. To date, this is the very first case where UZS ensued after and potentially as a consequence of TASS in a patient who had undergone P-IOL implantation. Although a direct causative element could not be pinpointed, the fact that the complication ensued after being operated in one surgical institution and not the other, could suggest some role of different sterilization and handling procedures, but no direct conclusion can be made on this case.

Both Subjective Emotional Distress and Visual Handicap Correlate with Belin ABCD Classification in the Worse Eye as Measured with the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ).

BACKGROUND: Keratoconus is a disease characterized by progressive corneal distortion and quality of vision. So far, no study using disease-specific scales has evaluated whether different stages of the disease correlate with higher quality of life (QoL) compromise. METHODS: A total of 114 patients with a confirmed diagnosis of Keratoconus were included in this retrospective study. All patients underwent a clinical and a Pentacam evaluation. They were also administered the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ). Belin ABCD criteria were used for Keratoconus classification. "Better eye" was defined as the eye with the lowest maximum keratometry value. Spearman Rank Order Correlation was used to determine the correlation between the different Belin criteria and the KEPAQ scores in both subscales. RESULTS: Mean age was 28.13 ± 11.57 years, with 39.47% of patients being male. Mean score for the KEPAQ-E was 2.33 ± 3.40 Logit, while for the KEPAQ-F, it was 1.85 ± 3.61 Logit. Criteria A (anterior elevation), B (posterior elevation) and D (visual acuity) in the worse eye correlated significantly with a greater decrease in QoL (p < 0.05 for all correlations). No correlation could be found regarding the better eye. CONCLUSION: A greater corneal distortion in the worse eye, as determined by Belin ABCD, is associated with a greater decrease in patient's QoL. Surgical improvement of the worse eye should probably be performed before surgery of the better eye, as it may provide a better response regarding the quality of life improvement.

Both sub-scales of the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ) are unidimensional and reliable.

BACKGROUND: Measuring quality of life in keratoconus is important and demands for well-constructed instruments and scales. To date, the Keratoconus End-Points Assessment Questionnaire (KEPAQ) is the only disease-specific scale to measure both functional and emotional compromise due to disease. Nevertheless, not much information exists regarding whether both sub-scales of the test show unidimensionality, a necessary condition in well-functioning instruments. METHODS: A sample of patients with a confirmed diagnosis of keratoconus were administered the full version of the KEPAQ. A Rasch analysis and principal component analysis were performed. RESULTS: A total of 249 patients with keratoconus were included. Their average age was 29.19 ± 10.91 years, and 51.40% were male. Mean score for the KEPAQ-E was 2.51 ± 3.29 logit while it was 2.26 ± 3.70 logit for the KEPAQ-F. For both sub-scales, Kaiser Criterion, Scree Plot Criterion, and Variability Criterion demonstrated unidimensionality. Reliability as measured by Cronbach's alpha was 0.85 for the KEPAQ-E and 0.87 for the KEPAQ-F. CONCLUSIONS: The KEPAQ is a robust, well-designed disease-specific questionnaire that shows unidimensionality. It can be reliably used to measure quality of life in keratoconus patients.

Development and Validation of the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ), a Disease-Specific Instrument for Evaluating Subjective Emotional Distress and Visual Function Through Rasch Analysis.

BACKGROUND: Keratoconus is a disease characterized by progressive distortion of the corneal anatomy, coupled with a decrease in vision. Assessing quality of life (QoL) in keratoconus is essential. So far, no instrument in the world has been designed to evaluate both visual function and emotional distress in this population. The purpose of the following study is to develop and validate the "Keratoconus End-Points Assessment Questionnaire" (KEPAQ) in a population of ectatic patients, the very first disease-specific scale to measure emotional latent traits in keratoconus. METHODS: A last generation, Rasch analysis method was used for scale validation. First, a number of focus groups were carried out to create a pool of potential items. Then, a series of processes (such as "Content Validity Index") was carried out to develop a prior, 20-question version of the KEPAQ. Then, a study including 150 keratoconus patients was performed, followed by a careful Rasch analysis to validate and optimize both sub-scales (Emotional Compromise, KEPAQ-E, and Functional Compromise, KEPAQ-F). RESULTS: Initially, 86 items were considered as potential elements. After test optimization, 20 items were retained. A total of 150 patients with a confirmed diagnosis of keratoconus were included for the Rasch analysis. The mean age was 29.84 ± 9.96 years. In 150 patients, 12.6% had a history of keratoplasty, 46.0% had corneal rings, and 31.3% had crosslinking. For both sub-scales, misfitting items were removed until no misfitting was determined by repetitive Rasch runs. For the final version of the KEPAQ-E sub-scale, variance explained by the model was 62.4% with a dimensional scale. Person Separation Index and Person Number of Strata were 2.43 and 3.57, respectively. For the final version of the KEPAQ-F sub-scale, variance explained by the model was 61.3% with a unidimensional scale. Person Separation Index and Person Number of Strata were 3.19 and 4.59, respectively. Both sub-scales showed excellent Person Reliability. CONCLUSION: The KEPAQ is a robust scale, developed and validated through the latest theoretical models. It shows excellent psychometric properties, which render it extremely useful for both clinical and research use. To date, the KEPAQ is the only disease-specific scale worldwide to evaluate both functional and emotional compromise in keratoconus patients.

Contralateral Posterior Chamber Phakic Intraocular Lens Implantation as Rehabilitation of Refractive Lens Exchange with a Monofocal Intraocular Lens in a Young, Nonpresbyopic, Bilateral Highly-Myopic Patient.

BACKGROUND: Refractive errors are widespread in the human population; nowadays, numerous surgical options allow for efficient and safe correction them. One of the main elements to ensure success in this kind of intervention will depend on the careful patient and surgical approach selection. Excimer laser corneal surgery is considered by most for low to moderate ametropias. Another option, which has been suggested may be safer, is to cut a small corneal lenticule with femtosecond laser, and then extracting it through a small incision. Nevertheless, in some specific cases, such as patients with high refractive error or those with some corneal abnormality, laser corneal ablations are considered unsafe from either a biomechanical or refractive standpoint. In this kind of particular cases, Phakic Intraocular Lens (P-IOL) implantation constitutes attractive, highly predictable and safe option. OBJECTIVE: The authors want to show the case of a young high-myopic woman, already pseudophakic in one eye, where the P-IOL implantation in the fellow eye yielded excellent short-term visual results, and high patient's satisfaction, is presented. MATERIALS: The authors present the case of a 32-years-old, highly myopic female patient underwent a Refractive Lens Exchange (RLE) with a monofocal Intraocular Lens (IOL) implantation in her left eye elsewhere, and developed severe visual issues, especially regarding near-work. Symptoms resolved through the implantation of a posterior chamber P-IOL in the contralateral eye. RESULTS: The postoperative course was unremarkable, inflammation was mild, and visual recovery was quick. There was no need to perform any procedure on her left eye or to use any reading glasses, as unilateral effective near vision through her right eye was enough for all her daily tasks. CONCLUSIONS: RLE in young pre-presbyopic highly myopic patients may not be an advisable alternative in most cases, because of the high risks of retinal complications observed. In addition, eliminating accommodation will cause significant limitations, and multifocal IOLs currently available are far from the quality of vision that a young human crystalline lens yields. On the other hand, implantation of a P-IOL is a good option if eye conditions are optimal, as it preserves natural accommodation. In this case an EyeCryl Phakic Toric® IOL showed excellent short-term refractive predictability and safety.