BCLA CLEAR presbyopia: Mechanism and optics.

With over a billion adults worldwide currently affected, presbyopia remains a ubiquitous, global problem. Despite over a century of study, the precise mechanism of ocular accommodation and presbyopia progression remains a topic of debate. Accordingly, this narrative review outlines the lenticular and extralenticular components of accommodation together with the impact of age on the accommodative apparatus, neural control of accommodation, models of accommodation, the impact of presbyopia on retinal image quality, and both historic and contemporary theories of presbyopia.

Short- and Long-Term Effects of a Multi-Component, Artificial Tear on Preocular Tear Film Stability, Tear Evaporation and Tear Film Optical Dynamic: A Prospective Randomized Double-Phase Study.

PURPOSE: To evaluate the short- (within 90 min) and long-term (after 21 days of treatment) effects of an artificial tear containing carbomer, hyaluronic acid, glycerol, and medium-chain triglycerides in patients with mild-to-moderate dry eye symptoms. METHODS: Subjects received the tested artificial tears in the right eye and control artificial tears in the left eye and were assessed 10, 30, 60, and 90 min after instillation in the short-term study phase. They received the study product in both eyes in the long-term phase. Non-invasive break-up time (NIBUT), tear lipid layer pattern, tear evaporation, and tear film objective optical dynamics (TFOOD) were measured in controlled environmental conditions. RESULTS: In total, 32 patients (10 males, mean age 42 ± 11 years) were enrolled. During the short-term phase, NIBUT increased significantly in the right eyes at all time points compared with baseline (all p < 0.05). Conversely, in the left eyes, NIBUT increased significantly at 10 and 30 min (p < 0.05). The tear evaporation values increased at 10 min and decreased at 30 and 60 min (p < 0.05) in the right eyes, while they increased only at 10 min (p < 0.05) in the left eyes. Compared with baseline, the TFOOD was significantly more stable at all time points in the right eyes (p < 0.05), while it was more stable at 10 and 30 min in the left eyes (p < 0.05). In the long-term phase, treated eyes showed a significant increase in NIBUT values, a significant reduction of tear evaporation, a significant improvement of tear lipid layer pattern, and a more stable TFOOD compared with baseline (all p < 0.05). Symptoms, measured with the Ocular Surface Disease Index questionnaire, were also significantly reduced compared with baseline (p < 0.05). CONCLUSION: The tested product increased tear film stability and reduced tear evaporation, normalizing lipid layer pattern and reducing symptoms in the short- and long-term observation.

CLEAR - Scleral lenses.

Scleral lenses were the first type of contact lens, developed in the late nineteenth century to restore vision and protect the ocular surface. With the advent of rigid corneal lenses in the middle of the twentieth century and soft lenses in the 1970's, the use of scleral lenses diminished; in recent times there has been a resurgence in their use driven by advances in manufacturing and ocular imaging technology. Scleral lenses are often the only viable form of contact lens wear across a range of clinical indications and can potentially delay the need for corneal surgery. This report provides a brief historical review of scleral lenses and a detailed account of contemporary scleral lens practice including common indications and recommended terminology. Recent research on ocular surface shape is presented, in addition to a comprehensive account of modern scleral lens fitting and on-eye evaluation. A range of optical and physiological challenges associated with scleral lenses are presented, including options for the clinical management of a range of ocular conditions. Future applications which take advantage of the stability of scleral lenses are also discussed. In summary, this report presents evidence-based recommendations to optimise patient outcomes in modern scleral lens practice.

Tear Film Characteristics During Wear of Daily Disposable Contact Lenses.

PURPOSE: To evaluate changes induced over time by three daily disposable (DD) contact lenses on tear meniscus height (TMH), pre-lens non-invasive break-up time (pre-lens NIBUT), tear film osmolarity (TO) and objective quality of vision (OQV). PATIENTS AND METHODS: Forty-six subjects enrolled in this prospective open-label unmasked non-randomized simultaneous comparative cross-over study. For the first week of the study, subjects wore a nesofilcon A lens in the right eye and a delefilcon A lens in the left eye. After 3 days of washout, for the second week, subjects wore a nesofilcon A lens in the left eye and a stenfilcon A lens in the right eye. TMH, pre-lens NIBUT, TO and OQV were measured before contact lens fitting and for each contact lens combination on day 1 at 20 minutes and on day 7 after ≥8 hours of wear. OQV measurement included the changes of objective scatter index (OSI), the stability index (SI) and the fluctuation index (FI) calculated in a range of time of 20 s from a blink. RESULTS: TMH was unchanged at 20 minutes wear of all lenses but was significantly reduced after 8 or more hours wear (on day 7) of delefilcon A and stenfilcon A, respectively. Pre-lens NIBUT was significantly reduced with all lenses, while no significant change in TO was observed with any lens. SI and FI increased significantly for all lenses at both wear times. CONCLUSION: While the presence of any contact lens on the eye challenges the tear film, nesofilcon A contact lenses, despite their high water content, compared to delefilcon A and stenfilcon A contact lenses, showed a lower overall effect. We speculate that superior tear film behavior while wearing nesofilcon A lenses may translate to improved subjective comfort, but this remains to be evaluated.

Immediate effect of a tear enhancer and meibomian gland expression on the corneal surface and whole eye higher order aberrations / Efecto inmediato de las lágrimas artificiales y de la expresión de las glándulas de Meibomio sobre las aberraciones de alto orden de la superficie corneal y totales

Purpose: To investigate changes in higher order ocular aberrations (HOA) induced by the administration of 0.15% sodium hyaluronate tear enhancer (TE) and meibomian gland expression (ME) on the tear film of normal subjects. Methods: HOA values were obtained from the corneal surface (CS) and whole eye (WE), using a corneal topographer and Shack-Hartmann aberrometer, from both eyes of 50 subjects (25 females, mean age ± sd 32.5 ± 11.0 years, and 25 males, 33.88 ± 11.2 years) for two pupil sizes (3 and 6 mm) in a dark environment. One drop of Blink ContactsTM (Abbott Medical Optics) was instilled into the right eye and HOA measurements repeated after 30 s. After 1h, the meibomian glands of the left lower eyelid were gently squeezed and HOA measurements repeated after 30s. Results: There was no significant difference for CS and WE root mean square (RMS) HOAs between right and left eyes before (both pupil sizes) and after TE use or ME (3 mm pupil). For 6mm pupil, TE use significantly reduced the WE RMS HOA (p < 0.05, mean ± sd) for Z40 (0.297 ± 0.136 to 0.053 ± 0.069), and Z55 (0.221 ± 0.372 to 0.098 ± 0.121) while ME significantly increased CS RMS HOA (p < 0.05, mean ± sd) for Z3-3 (0.799 ± 1.178 to 1.302±1.991) and Z44 (0.594±1.184 to 0.988 ± 1.463). In general, the change in HOA was significantly correlated with the initial value before TE use or ME (p < 0.05). Conclusion: There were no detectable differences between right and left eyes. For the 6mm pupil, the tear enhancer tended to improve optical performance of the WE and meibomian gland expression tended to reduce the optical performance at the CS

Objetivo: Estudiar los cambios de las aberraciones oculares de alto orden (HOA) inducidas por la aplicación de las lágrimas artificiales con 0,15% de hialuronato sódico y la expresión de las glándulas de Meibomio (ME) en la película lagrimal en sujetos normales. Métodos: Se obtuvieron los valores de HOA de la superficie corneal (SC) y de la totalidad del ojo, utilizando un topógrafo corneal y un aberrómetro Shack-Hartmann, de ambos ojos de 50 sujetos (25 mujeres, edad media ± DE 32,5 ± 11 años, y 25 varones, 33,88 ± 11,2 años) para dos tamaños de pupila (3 y 6 mm) en un entorno oscuro. Se instiló una gota de Blink ContactsTM (Abbott Medical Optics) en el ojo derecho, repitiéndose las mediciones de HOA transcurridos 30 segundos. Al cabo de 1 hora, se presionaron suavemente las glándulas de Meibomio del párpado inferior del ojo izquierdo y se repitieron las mediciones de HOA al cabo de 30 segundos. Resultados: No se produjo diferencia significativa en el error cuadrático médio (RMS) de HOA de la superficie corneal y la totalidad del ojo entre los ojos derecho e izquierdo (ambos tamaños de pupila) antes o después del uso de las lágrimas artificiales o ME (pupila de 3 mm). Para pupilas de 6mm, el uso de lágrimas artificiales redujo significativamente el RMS de HOA de la totalidad del ojo (p< 0,05, media ± DE) para Z04 (de 0,297 ± 0,136 a 0,053 ± 0,069), y Z55 (de 0,221 ± 0,372 a 0,098 ± 0,121) mientras que ME incrementó significativamente el RMS de HOA (p < 0,05, media ± DE) para Z−33 (de 0,799 ± 1,178 a 1,302 ± 1,991) y Z44 (de 0,594 ± 1,184 a 0,988 ± 1,463). En general, el cambio de HOA guardó una correlación significativa con el valor inicial antes del uso de lágrimas artificiales o ME (p < 0,05). Conclusión: No se observaron diferencias detectables entre los ojos derecho e izquierdo. Para la pupila de 6 mm, la lágrima artificial tendió a mejorar el rendimiento óptico de la totalidad del ojo, y la expresión de las glándulas de Meibomio tendió a reducir el rendimiento óptico de la superficie corneal

Immediate effect of a tear enhancer and meibomian gland expression on the corneal surface and whole eye higher order aberrations.

PURPOSE: To investigate changes in higher order ocular aberrations (HOA) induced by the administration of 0.15% sodium hyaluronate tear enhancer (TE) and meibomian gland expression (ME) on the tear film of normal subjects. METHODS: HOA values were obtained from the corneal surface (CS) and whole eye (WE), using a corneal topographer and Shack-Hartmann aberrometer, from both eyes of 50 subjects (25 females, mean age±sd 32.5±11.0 years, and 25 males, 33.88±11.2 years) for two pupil sizes (3 and 6mm) in a dark environment. One drop of Blink Contacts™ (Abbott Medical Optics) was instilled into the right eye and HOA measurements repeated after 30s. After 1h, the meibomian glands of the left lower eyelid were gently squeezed and HOA measurements repeated after 30s. RESULTS: There was no significant difference for CS and WE root mean square (RMS) HOAs between right and left eyes before (both pupil sizes) and after TE use or ME (3mm pupil). For 6mm pupil, TE use significantly reduced the WE RMS HOA (p<0.05, mean±sd) for Z40 (0.297±0.136 to 0.053±0.069), and Z55 (0.221±0.372 to 0.098±0.121) while ME significantly increased CS RMS HOA (p<0.05, mean±sd) for Z3-3 (0.799±1.178 to 1.302±1.991) and Z44 (0.594±1.184 to 0.988±1.463). In general, the change in HOA was significantly correlated with the initial value before TE use or ME (p<0.05). CONCLUSION: There were no detectable differences between right and left eyes. For the 6mm pupil, the tear enhancer tended to improve optical performance of the WE and meibomian gland expression tended to reduce the optical performance at the CS.

Myopia onset and role of peripheral refraction.

BACKGROUND: To determine the peripheral refraction characteristics related to 18-month changes in refraction in Caucasian (Mediterranean) children. METHODS: Non-cycloplegic peripheral refraction at 10° intervals over the central ±30° of horizontal visual field over 18 months (baseline, 12 months, and 18 months of follow-up) was conducted in 50 healthy children who were 8 years old. Axial length (AL) was also recorded. Relative peripheral refraction (RPR) was calculated and eyes were divided into three study groups: non-myopic eyes, myopic eyes, and eyes that develop myopia. RESULTS: Myopic eyes showed hyperopic RPR and emetropic and hyperopic eyes showed myopic RPR. Univariate analysis of variance did not find any statistically significant effect of peripheral refraction (F36=0.13; P=1.00) and RPR (F36=0.79; P=0.80) on myopia onset (eyes that developed myopia along the study). All the studied groups showed an increase of AL, without statistically significant differences between the studied groups (F6=0.09; P=0.99). CONCLUSION: Hyperopic relative peripheral shift change in eyes that develop myopia has been found with differences in RPR between myopic (hyperopic RPR) and hyperopic or emmetropic eyes (with myopic RPR). The results suggest that RPR cannot predict development or progression of myopia in Caucasian (Mediterranean) children and the efficacy in slowing myopia progression obtained with treatments that manipulate the peripheral refraction is not just driven with RPR.

Intrasubject tear osmolarity changes with two different types of eyedrops.

PURPOSE: To analyze tear osmolarity over time after instillation of two commercially available eyedrops. METHODS: This prospective, nonrandomized, simultaneous, comparative, open-label, unmasked study included 40 eyes of 20 consecutive subjects (mean age, 34.8 ± 11.8 years) with a diagnosis of moderate dry eye. Subjects were instructed to administer contralaterally controlled lubricants to the right ([RE] Blink Intensive Tears, Abbott Medical Optics, Santa Ana, CA) and left ([LE] Optive Eye Drops, Allergan Inc., Irvine, CA) eyes three times daily for 21 days. The impact of hypoosmotic (RE) and osmoprotective (LE) drops on tear osmolarity (TearLab Osmolarity System, TearLab Corporation, San Diego, CA) was measured before and 30, 60, 90, 120, and 180 minutes after instillation of the first set of drops. Follow-up measurements were performed 22 days later, 1 day after the subjects stopped using the drops. RESULTS: In RE, compared with baseline, tear osmolarity values were significantly reduced at all time points after instillation, including at 180 minutes (p < 0.01). In LE, osmolarity was significantly reduced from baseline at all time points through 120 minutes (p < 0.01) but returned toward baseline at 180 minutes (p < 0.11). The minimal value reached at 90 minutes after instillation or the average reduction from baseline osmolarity was 27.6 ± 9.5 mOsm/L for RE as compared with 22.1 ± 12.3 mOsm/L for LE. Both groups showed significantly lower tear osmolarity at 21 days compared with that at baseline (hypoosmotic, 307.8 ± 11.9 mOsm/L vs. 329.4 ± 8.4 mOsm/L, p < 0.001; osmoprotective, 316.1 ± 12.5 mOsm/L vs. 327.6 ± 8.4 mOsm/L, p < 0.002). CONCLUSIONS: Our results showed that both eyedrops reduced tear osmolarity within a short time frame after drop instillation (i.e., up to 120 minutes) and after a longer time frame (i.e., 21 days of application). However, hypoosmotic drops with sodium hyaluronate reduce tear osmolarity at a greater and more sustained rate than glycerin and carboxymethylcellulose-based osmoprotectants.