Pharmacological treatments for the correction of presbyopia.

Presbyopia affects between 1.7 and 2 billion people worldwide. Presbyopia significantly impacts productivity and quality of life in both developed and developing countries. During accommodation, the human eye changes its dioptric power by altering the shape of the lens, but the exact nature of this change has not been fully explained. Recently, topical treatments have been marketed for the treatment of presbyopia and others are under investigation. In order to prepare a review of these novel therapies, we searched the major biomedical search engines. We found 15 randomized clinical trials and 12 reviews that met our review criteria. There are two different strategies for this purpose, the pinhole effect that increases depth of focus and "crystalline lens relaxation" for which parasympathetic mimetics and lens oxidation intermediates have been used. The results are generally favorable in terms of improvement of near visual acuity, although the follow-up period of the studies is short. These are novel strategies in the early stages of research that could be useful in the treatment of presbyopia.

Evaluación del músculo ciliar y del grosor escleral anterior en miopes altos mediante tomografía de coherencia óptica / Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography

Propósito: Evaluar las dimensiones del músculo ciliar (MC) y del grosor escleral anterior (AST) in vivo en miopes altos mediante tomografía de coherencia óptica de fuente de barrido (SS-OCT) y comparar con sujetos emétropes e hipermétropes.MétodosEstudio transversal en el que se incluyeron 34 miopes altos (≥−6dioptrías [D]), 90 emétropes (−1 a +1D) y 38 hipermétropes (≥+3,5D). Se midieron el grosor del MC (CMT) y el AST en los cuadrantes temporal y nasal a 1, 2 y 3mm del espolón escleral utilizando la SS-OCT. Además, se evaluó la longitud del MC (CML).ResultadosLas dimensiones tanto del CML como del CMT en cualquiera de sus puntos de medida fueron mayores en miopes altos y en emétropes que en hipermétropes, tanto en el cuadrante nasal como en el temporal (p<0,001). Sin embargo, no existieron diferencias entre miopes magnos y emétropes para ninguno de los parámetros (p≥0,076), salvo para el CMT a 3mm en temporal (p<0,001). No existieron diferencias en el AST entre miopes altos, emétropes e hipermétropes, en ninguno de los puntos de medida ni cuadrantes estudiados (p>0,05).ConclusionesLa SS-OCT permite medir el MC in vivo, no observándose diferencias en sus dimensiones entre miopes altos y emétropes, pero sí que fueron menores en hipermétropes. En la medida de la esclera anterior no se observaron diferencias entre los tres grupos analizados según la refracción. (AU)

Purpose: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects.MethodsCross-sectional study that included 34 high myopic patients (≥−6 diopters [D]), 90 emmetropes (−1 to +1D) and 38 hyperopic patients (≥+3.5D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated.ResultsThe dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P<.001). However, there were no differences between high myopes and emmetropes for any of the parameters (P≥.076) except for the CMT at 3mm in the temporal quadrant (P<.001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P>.05).ConclusionsThe SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction. (AU)

Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography.

PURPOSE: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects. METHODS: Cross-sectional study that included 34 high myopic patients (≥ -6 diopters [D]), 90 emmetropes (-1 to +1 D) and 38 hyperopic patients (≥ +3.5 D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3 mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated. RESULTS: The dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P < .001). However, there were no differences between high myopes and emmetropes for any of the parameters (P ≥ .076) except for the CMT at 3 mm in the temporal quadrant (P < .001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P > .05). CONCLUSIONS: The SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction.

Multisectorial changes in the ciliary muscle during accommodation measured with high-resolution optical coherence tomography / Alterações multissetoriais no músculo ciliar durante a acomodação com uma tomografía de coerência óptica de alta resolução

ABSTRACT Purpose: To measure changes in the anterior ciliary muscle during accommodation at the nasal, superior, temporal, and inferior sectors by means of an anterior chamber optical coherence tomographer, and correlate them with vergence changes. Methods: Twenty-four subjects with healthy, phakic eyes, whose mean age was 27.1 ± 8.9 years, underwent measurement with an anterior chamber optical coherence tomographer. The anterior ciliary muscle was measured at the nasal, temporal, superior, and inferior sectors for 0, -1, -2, and -3 D of vergence. A linear model was used to assess the correlation of each eye parameter with the accommodative demand. Results: The anterior ciliary muscle area significantly increased with accommodation for each sector, with a maximum increase of about 30% for the nasal-temporal sectors and about 25% for the inferior-temporal sectors. The linear model showed a tendency toward a positive relationship between change in the ciliary muscle area of each sector and vergence. Conclusion: The anterior ciliary muscle area tends to increase with accommodation, although the increase has been shown to be symmetric between the pair sectors superior-nasal and inferior-temporal. These results may help to increase understanding of accommodation biometry and biomechanics.

RESUMO Objetivo: Medir as alterações do músculo ciliar anterior durante a acomodação nos setores nasal, superior, temporal e inferior, através de um tomógrafo de coerência óptica de câmara anterior, e correlacioná-las com alterações de vergência. Métodos: Vinte e quatro indivíduos com olhos saudáveis e fácicos, com idade média de 27,1 ± 8,9 anos, foram submetidos à medida com um tomógrafo de coerência óptica de câmara anterior. O músculo ciliar anterior foi medido nos setores nasal, temporal, superior e inferior para 0, -1, -2 e -3D de vergência. Um modelo linear foi utilizado para avaliar a correlação de cada parâmetro do olho com a demanda acomodativa. Resultados: A área do músculo ciliar anterior aumentou significativamente com a acomodação em cada setor, com um aumento máximo foi de cerca de 30% para os setores naso-temporais, e cerca de 25% para os inferiores-temporais. O modelo linear mostrou uma tendência para uma relação positiva entre a alteração da área do músculo ciliar de cada setor e a vergência. Conclusão: A área do músculo ciliar anterior tende a aumentar com a acomodação, embora o aumento tenha se mostrado simétrico entre os setores superior-nasal e inferior-temporal. Estes resultados podem ajudar a aumentar a compreensão da biometria e biomecânica da acomodação.

Effect of age in the ciliary muscle during accommodation: Sectorial analysis.

PURPOSE: To compare changes in the ciliary muscle area at different sectors between pre-presbyopic and presbyopic eyes during accommodation by means of an anterior segment optical coherence tomographer (OCT). METHODS: The anterior ciliary muscle area was measured in 20 healthy and phakic pre-presbyopic eyes, whose mean age was 23.3±4.4 years, and in 20 healthy and phakic presbyopic eyes, whose mean age was 46.5±5.2 years. The relative change in the cross-sectional area of the ciliary muscle was measured at the nasal, inferior, and temporal sectors between 0 and -3 D of vergence, in -1 D step. A linear model was used to assess the correlation of each eye parameter with the accommodative demand. RESULTS: Each population group showed a significant increase in the anterior ciliary muscle area for each sector. The maximum increase in the ciliary muscle area within the pre-presbyopic group was about 30%, and for the presbyopic one was about 25%. At the same time, it was obtained that the larger the vergence, the larger the variability. Furthermore, the linear model showed a positive tendency between the change in the ciliary muscle area of each sector and the vergence for both population groups, which coefficient of determination was in all cases greater than 0.93. CONCLUSION: The anterior ciliary muscle area tends to increase with accommodation. The presbyopic nasal, inferior, and temporal ciliary muscle seem to have the same contractile capability as the young presbyopic ciliary muscle. These results might help to increase the evidences in the knowledge regarding the modern understanding of accommodation biometry and biomechanics.