Prediction of distance visual acuity in presbyopic astigmatic subjects.

This study was aimed to determine the effect of the amount of astigmatism on distance visual acuity, and to provide a prediction formula of visual acuity according to astigmatism, in a presbyopic population. We comprised 318 eyes of 318 consecutive patients (158 phakic and 160 pseudophakic subjects) without any eye diseases, except for refractive errors with astigmatism of 3 diopter or less. We assessed the relationship of the spherical equivalent visual acuity (SEVA) with astigmatism, and also provided a regression formula of visual acuity according to astigmatism in such subjects. We found a significant correlation between the SEVA and the amount of astigmatism (r = 0.715, p < 0.001) in the entire study population. We obtained similar results, not only in phakic eyes (r = 0.718, p < 0.001), but also in pseudophakic eyes (r = 0.717, p < 0.001). The regression formula was expressed as follows: y = 0.017x2 + 0.125x - 0.116 (R2 = 0.544), where y = logMAR SEVA, and x = astigmatism. We also found no significant differences in the SEVA for matched comparison among the with-the-rule (WTR), against-the-rule (ATR), and oblique (OBL) astigmatism subgroups (p = 0.922). These regression formulas may be clinically beneficial not only for estimating the visual prognosis after astigmatic correction, but also for determining the surgical indication of astigmatic correction.

Autofocals: Evaluating gaze-contingent eyeglasses for presbyopes.

As humans age, they gradually lose the ability to accommodate, or refocus, to near distances because of the stiffening of the crystalline lens. This condition, known as presbyopia, affects nearly 20% of people worldwide. We design and build a new presbyopia correction, autofocals, to externally mimic the natural accommodation response, combining eye tracker and depth sensor data to automatically drive focus-tunable lenses. We evaluated 19 users on visual acuity, contrast sensitivity, and a refocusing task. Autofocals exhibit better visual acuity when compared to monovision and progressive lenses while maintaining similar contrast sensitivity. On the refocusing task, autofocals are faster and, compared to progressives, also significantly more accurate. In a separate study, a majority of 23 of 37 users ranked autofocals as the best correction in terms of ease of refocusing. Our work demonstrates the superiority of autofocals over current forms of presbyopia correction and could affect the lives of millions.

Latanoprost could exacerbate the progression of presbyopia.

PURPOSE: Prostaglandin analogues (PG) reduce intra-ocular pressure by enhancing uveoscleral flow at the ciliary body, which controls accommodation via the ciliary muscle. We investigated the effect of PG on accommodation and presbyopia progression in glaucoma patients. METHODS: We conducted a clinic-based, retrospective, cross-sectional study. Inclusion criteria were bilateral phakic patients aged 40-69 years with best corrected visual acuity better than 20/30. Exclusion criteria were any disease affecting vision other than glaucoma and history of ocular surgery. Subjects with no prescription or vision-affecting disease served as controls (n = 260). The glaucoma patients were prescribed eye drops containing 0.005% latanoprost for more than six months (n = 23). We measured the binocular near add power at a distance of 30 cm in both groups and compared the results using Kaplan-Meier analysis. RESULTS: The mean age (± SD) of the control subjects was 51.5 ± 5.2 years and 39% were male. Similarly, the glaucoma patients had a mean age of 51.0 ± 7.2 years and 39% were male. There were no significant differences in age, gender, intra-ocular pressure, spherical equivalent, astigmatism, or anisometropia between groups. Survival analysis indicated that the glaucoma patients in this study reached the endpoint (near add power of +3.00 D) significantly earlier than control patients (P = 0.0001; generalized Wilcoxon test). CONCLUSIONS: Exacerbation of presbyopia progression in glaucoma patients is a potential side effect of latanoprost eyedrops.

The Light Sword Lens - A novel method of presbyopia compensation: Pilot clinical study.

PURPOSE: Clinical assessment of a new optical element for presbyopia correction-the Light Sword Lens. METHODS: Healthy dominant eyes of 34 presbyopes were examined for visual performance in 3 trials: reference (with lens for distance correction); stenopeic (distance correction with a pinhole ϕ = 1.25 mm) and Light Sword Lens (distance correction with a Light Sword Lens). In each trial, visual acuity was assessed in 7 tasks for defocus from 0.2D to 3.0D while contrast sensitivity in 2 tasks for defocus 0.3D and 2.5D. The Early Treatment Diabetic Retinopathy Study protocol and Pelli-Robson method were applied. Within visual acuity and contrast sensitivity results degree of homogeneity through defocus was determined. Reference and stenopeic trials were compared to Light Sword Lens results. Friedman analysis of variance, Nemenyi post-hoc, Wilcoxon tests were used, p-value < 0.05 was considered significant. RESULTS: In Light Sword Lens trial visual acuity was stable in tested defocus range [20/25-20/32], Stenopeic trial exhibited a limited range of degradation [20/25-20/40]. Light Sword Lens and reference trials contrast sensitivity was high [1.9-2.0 logCS] for both defocus cases, but low in stenopeic condition [1.5-1.7 logCS]. Between-trials comparisons of visual acuity results showed significant differences only for Light Sword Lens versus reference trials and in contrast sensitivity only for Light Sword Lens versus stenopeic trials. CONCLUSIONS: Visual acuity achieved with Light Sword Lens correction in presbyopic eye is comparable to stenopeic but exhibits none significant loss in contrast sensitivity. Such correction method seems to be very promising for novel contact lenses and intraocular lenses design.

Patient-specific determination of change in ocular spherical aberration to improve near and intermediate visual acuity of presbyopic eyes.

The purpose was to determine the optimum negative spherical aberration induction required to improve near and intermediate visual acuity (VA) of presbyopic eyes. A total of 174 normal and diabetic (no retinopathy) presbyopic eyes (age ≥ 40 years) were measured with visual adaptive optics simulator (Voptica, Spain). First, baseline uncorrected VA and aberrations were measured. VA at 40 cm (near), 80 cm (intermediate) and distance was measured. Then, a negative spherical aberration (SA) was added to baseline ocular SA, and VA at all targets was reassessed after correction of distance refractive error. Clinically, baseline SA and root mean square of higher order aberrations were similar between the normal and diabetic presbyopic eyes. Baseline VA of the diabetic eyes at near and intermediate was better than the same of normal eyes (P = 0.001). After SA change, VA at near and intermediate of both normal and diabetic presbyopic eyes improved. However, fewer diabetic eyes needed higher SA change than normal eyes (P = 0.03). The corresponding trends with change in VA at near and intermediate were also similar between the normal and diabetic eyes. Patient-specific modulation of ocular SA to improve near and intermediate VA in a large cohort of eyes was successful in improving VA, sometimes even distance VA.

Short-term comparison between extended depth-of-focus prototype contact lenses and a commercially-available center-near multifocal / Comparación a corto plazo entre las lentes prototipo de profundidad de campo extendidas y las lentes multifocales de visión central-próxima, comercialmente disponibles

Purpose: To compare the visual performance of prototype contact lenses which extend depthof-focus (EDOF) by deliberate manipulation of multiple higher-order spherical aberration terms and a commercially-available center-near lens (AIR OPTIX Aqua Multifocal, AOMF). Methods: This was a prospective, cross-over, randomized, single-masked (participant), shortterm clinical trial where 52 participants (age 45-70 years) were stratified as low, medium or high presbyopes and wore EDOF and AOMF on different days. Objective measures comprised high and low contrast visual acuity (HCVA/LCVA, log MAR), and contrast sensitivity (log units) at 6 m; HCVA at 70 cm, 50 cm and 40 cm and stereopsis (seconds of arc) at 40 cm. HCVA at 70 cm, 50 cm and 40 cm were measured as «comfortable acuity» rather than conventional resolution acuity. Subjective measures comprised clarity-of-vision and ghosting at distance, intermediate and near, overall vision satisfaction and ocular comfort (1-10 numeric rating scale) and lens purchase (yes/no response). Statistical analysis included repeated measures ANOVA, paired t-tests and McNemar’s test. Results: Significant differences between lens types were independent of strata (p ≥ 0.119). EDOF was significantly better than AOMF for HCVA at 40 cm (0.42 ± 0.18 vs. 0.48 ± 0.22, p = 0.024), stereopsis (98 ± 88 vs. 141 ± 114, p < 0.001), clarity-of-vision at intermediate (8.5 ± 1.6 vs. 7.7 ± 1.9, p = 0.006) and near (7.3 ± 2.5 vs. 6.2 ± 2.5, p = 0.005), lack-of-ghosting (p = 0.012), overall vision satisfaction (7.5 ± 1.7 vs. 6.4 ± 2.2, p < 0.001) and ocular comfort (9.0 ± 1.0 vs. 8.3 ± 1.7, p = 0.002). Significantly more participants chose to only-purchase EDOF (33% vs. 6%, p = 0.003).). There were no significant differences between lens types for any objective measure at 6 m or clarity-of-vision at distance (p ≥ 0.356). Conclusions: EDOF provides better intermediate and near vision performance in presbyopes than AOMF with no difference for distance vision during short-term wear (AU)

Objetivo: Comparar el rendimiento visual de prototipos de lentes de contacto con las de profundidad de campo extendida (EDOF), mediante la manipulación deliberada de múltiples aberraciones esféricas de alto orden y las lentes de visión simultánea centro-cerca comercialmente disponibles (AIR OPTIX Aqua Multifocal, AOMF). Métodos: Ensayo clínico prospectivo, transversal, aleatorizado, con máscara única (participante), y a corto plazo, en el que se estratificó la presbicia de 52 participantes (de edades comprendidas entre 45 y 70 años) como baja, media o alta; dichos participantes utilizaron lentes EDOF y AOMF en días diferentes. Las mediciones objetivas incluyeron la agudeza visual de alto y bajo contraste (HCVA/LCVA, log MAR), y la sensibilidad al contraste (unidades log) a 6 m, HCVA a 70 cm, 50 cm y 40 cm, y estereopsis (segundos de arco) a 40 cm. La HCVA a 70 cm, 50 cm y 40 cm se midió como «agudeza de confort» en lugar de la agudeza de resolución convencional. Las mediciones subjetivas incluyeron la claridad de visión y la visión fantasma (ghosting) a distancia, la satisfacción con la visión general intermedia y lejana, el confort ocular (escala de clasificación numérica de 1a 10) y la adquisición de lentes de contacto (respuesta sí/no). El análisis estadístico incluyó la prueba ANOVA con medidas repetidas, la prueba de t pareada, y la prueba de McNemar. Resultados: La significación de las diferencias entre los tipos de lentes fue independiente de los estratos (p ≥ 0,119). Los resultados de EDOF fueron considerablemente mejores que los de AOMF en cuanto a HCVA a 40 cm (0,42 ± 0,18 frente a 0,48 ± 0,22, p = 0,024), estereopsis (98 ± 88 frente a 141 ± 114, p < 0,001), claridad de visión intermedia (8,5 ± 16 frente a 7,7 ± 1,9, p = 0,006) y próxima (7,3 ± 2,5 frente a 6,2 ± 2,5, p = 0,005), ausencia de visión fantasma (p = 0,012), satisfacción con la visión general (7,5 ± 1,7 frente a 6,4 ± 2,2, p < 0,001) y confort ocular (9,0 ± 1,0 frente a 8,3 ± 1,7, p = 0,002). Un número considerable de participantes optó por adquirir únicamente EDOF (33% frente al 6%, p = 0,003). No se produjeron diferencias significativas entre los dos tipos de lentes en relación a las mediciones objetivas a 6 m, ni a la claridad de visión lejana (p ≥ 0,356). Conclusiones: Las lentes EDOF proporcionaron un mejor rendimiento de la visión intermedia y próxima en pacientes con presbicia que las lentes AOMF, sin que se produjeran diferencias en cuanto a visión lejana con el uso a corto plazo (AU)

Effect of defocus on response time in different age groups: A pilot study / Efecto del desenfoque en el tiempo de respuesta en diferentes grupos de edad: estudio piloto

Purpose: To assess the response time associated with visual performance (VP) tasks in the presence of defocus in different presbyopic populations. Methods: 58 eyes between the ages of 35 and 50 years were studied. Subjects were categorized as pre-presbyopic (35-39 years), early-presbyopic (40-45 years), and mid-presbyopic (46-50 years). VP measurements obtained monocularly included distance and near high contrast (HC) and low contrast (LC) optotype recognition, and contrast threshold at 12cpd for different defocus magnitudes between 0D and 3D in 1D steps. Response time defined as the time taken to recognize and verbalize an optotype, was compared among different presbyopic age groups. Results: From 58 eyes, mean (SD) response time for high contrast distance visual acuity for 0D through 3D ranged between 1.48 (0.23) and 1.87 (0.31)s, whereas low contrast distance visual acuity ranged between 1.5 (0.22) and 2.09 (0.49)s. Mean response time for high contrast near visual acuity for 0D through 3D ranged between 1.56 (0.19) and 2.23 (0.45)s. However, for low contrast near visual acuity it ranged between 1.75 (0.32) and 2.71 (0.94)s. Mean (SD) response time for 12cpd ranged between 2.11 (0.50) and 5.72 (1.09)s. ANOVA revealed a significant difference in response time for distance, near visual acuity and contrast sensitivity as a function of defocus for different age groups. Conclusions: Response time is increased in the presence of increasing defocus for both distance and near visual acuity and could impact on performance for critical tasks. Full correction of visual acuity at distance and near in presbyopes is warranted always (AU)

Objetivo: Evaluar el tiempo de respuesta asociado a las tareas del desempeño visual (DV) en presencia de desenfoque, en diferentes poblaciones présbitas. Métodos: Se estudiaron 58 ojos de personas en edades comprendidas entre 35 y 50 años. Se clasificó a los sujetos conforme a las siguientes categorías: pre-presbicia (35-39 años), presbicia temprana (40-45 años), y presbicia media (46-50 años). Las mediciones del desempeño visual obtenidas de forma monocular incluyeron el reconocimiento de optotipos cercanos y lejanos de alto y bajo contraste y el umbral de contraste a 12cpd para las diferentes magnitudes de desenfoque, entre 0D y 3D, a intervalos de 1D. El tiempo de respuesta es el tiempo empleado en reconocer y verbalizar un optotipo, y se comparó entre los diferentes grupos de edad de los individuos présbitas. Resultados: De los 58 ojos, el tiempo de respuesta media (DE) para la agudeza visual de la distancia a alto contraste, entre 0D y 3D, osciló entre 1,48 (0,23) y 1,87 (0,31) segundos, mientras que la agudeza visual de la distancia a bajo contraste osciló entre 1,5 (0,22) y 2,09 (0,49) segundos. El tiempo de respuesta media para la agudeza visual cercana de alto contraste entre 0D y 3D osciló entre 1,56 (0,19) y 2,23 (0,45) segundos. Sin embargo para la agudeza visual cercana de bajo contraste osciló entre 1,75 (0,32) y 2,71 (0,94) segundos. El tiempo de respuesta media (DE) para 12cpd osciló entre 2,11 (0,50) y 5,72 (1,09) segundos. ANOVA reveló una diferencia significativa en cuanto al tiempo de respuesta para la distancia, agudeza visual cercana y sensibilidad de contraste como función del desenfoque para los diferentes grupos de edad. Conclusiones: El tiempo de respuesta se eleva al incrementarse el desenfoque en la agudeza visual lejana y cercana, pudiendo repercutir sobre el desempeño de ciertas tareas esenciales. La corrección plena de la agudeza visual cercana y lejana en individuos présbitas debe de ser siempre garantizada (AU)

Non-enzymatic glycation of α-crystallin as an in vitro model for aging, diabetes and degenerative diseases.

Alpha crystallin, a small heat-shock protein, has been studied extensively for its chaperone function. Alpha crystallin subunits are expressed in stress conditions and have been found to prevent apoptosis by inhibiting the activation of caspase pathway. Non-enzymatic glycation of protein leads to the formation of advanced glycation end-products (AGEs). These AGEs bind to receptors and lead to blocking the signaling pathways or cause protein precipitation as observed in aggregation-related diseases. Methylglyoxal (MGO) is one of the major glycating agents expressed in pathological conditions due to defective glycolysis pathway. MGO reacts rapidly with proteins, forms AGEs and finally leads to aggregation. The goal of this study was to understand the non-enzymatic glycation-induced structural damage in alpha crystallin using biophysical and spectroscopic characterization. This will help to develop better disease models for understanding the biochemical pathways and also in drug discovery.

Influences of luminance and accommodation stimuli on pupil size and pupil center location.

PURPOSE: We investigated effects of luminance and accommodation stimuli on pupil size and pupil center location, and their implications for progressive addition lens wear. METHODS: Participants were young and older adult groups (n = 20; 22 ± 2 years; age range, 18-25 years; and n = 19; 49 ± 4 years; age range, 45-58 years). A wave aberrometer included a relay system to allow a 12.5° × 11° background for the internal fixation target. Participants viewed the target under a matrix of conditions with luminance levels 0.01, 3.7, 120, and 6100 cd/m(2), and with accommodation stimuli up to 6 diopters (D) in 2 D steps. Pupil sizes and their centers, relative to limbus centers, were determined from anterior eye images. RESULTS: With luminance increase, reduction in pupil size was accentuated by increase in accommodation stimulus in the young, but not in the older, group. As luminance increased, pupil center location altered. This was nasally in both groups with an average shift of approximately 0.12 mm. Relative to the lowest stimulus condition, the mean of the maximum absolute pupil center shifts was 0.26 ± 0.08 mm for both groups with individual shifts up to 0.5 mm, findings consistent with previous studies. There was no significant effect of accommodation on pupil center locations for either age group, or evidence that location was influenced by the combination of luminance and accommodation stimulus that resulted in any particular pupil size. CONCLUSIONS: Variations in luminance and accommodation influence pupil size, but only the former affects pupil center location significantly. Pupil center shifts are too small to be of concern in fitting progressive addition lenses.

Uncovering foveal crowding?

Visual crowding, as context modulation, reduce the ability to recognize objects in clutter, sets a fundamental limit on visual perception and object recognition. It's considered that crowding does not exist in the fovea and extensive efforts explored crowding in the periphery revealed various models that consider several aspects of spatial processing. Studies showed that spatial and temporal crowding are correlated, suggesting a tradeoff between spatial and temporal processing of crowding. We hypothesized that limiting stimulus availability should decrease object recognition in clutter. Here we show, for the first time, that robust contour interactions exist in the fovea for much larger target-flanker spacing than reported previously: participants overcome crowded conditions for long presentations times but exhibit contour interaction effects for short presentation times. Thus, by enabling enough processing time in the fovea, contour interactions can be overcome, enabling object recognition. Our results suggest that contemporary models of context modulation should include both time and spatial processing.

Anterior chamber angle evaluation with ultrasound biomicroscopy and optical coherence tomography in eyes implanted with a Crystalens.

This study employs optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) imaging as well as optical aberrometry to examine correlations between the anterior chamber angle aperture and visual acuity for near vision as well as coma along the horizontal and vertical axes in eyes implanted with an accommodative intraocular lens (Crystalens). A retrospective comparative consecutive case series of 22 eyes of 11 patients (5 males) uneventfully implanted with a Crystalens. Eyes with signs of posterior capsular opacification were excluded. All eyes were examined with 40 MHz UBM (Ellex Eyecubed) and spectral-domain OCT (Zeiss Visante). The angle aperture along the horizontal and vertical meridians was recorded based on the software of the systems. The coma root mean square (RMS) scores for the horizontal and vertical meridians were also recorded with the iTrace aberrometer. The anterior chamber angle was significantly wider along the horizontal axis compared with the vertical axis by UBM (46.37° and 44.20°, respectively) and by OCT (46.79° and 43.58°, respectively) (p = 0.02 in both cases, paired-samples t test). The correlations between the logMAR-converted Jaeger near vision score and the horizontal or vertical angle apertures was not statistically significant. Horizontal coma RMS was significantly inversely correlated with the horizontal angle aperture (r = -0.45, p = 0.03 and r = -0.39, p = 0.04 by OCT and UBM, respectively). Measurement of the horizontal angle aperture by the modalities used may represent an anatomical and clinical predictor of the optical aberrations induced by the Crystalens.

Vignetting and field of view with the KAMRA corneal inlay.

PURPOSE: To evaluate the effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field. METHODS: A KAMRA inlay was "implanted" into a theoretical eye model in a corneal depth of 200 microns. Corneal radius was varied to a steep, normal, and flat (7.37, 7.77, and 8.17 mm) version keeping the proportion of anterior to posterior radius constant. Pupil size was varied from 2.0 to 5.0 mm. Image brightness was determined for field angles from -70° to 70° with and without KAMRA and proportion of light attenuation was recorded. RESULTS: In our parameter space, the attenuation in brightness ranges in between 0 and 60%. The attenuation in brightness is not affected by corneal shape. For large field angles where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil sizes (2.0 and 2.5 mm) and field angles of 20-40°, up to 60% of light may be blocked with the KAMRA. CONCLUSION: For combinations of pupil sizes and field angles, the attenuation of image brightness reaches levels up to 60%. Our theoretical findings have to be clinically validated with detailed investigation of this vignetting effect.

Corneal imaging of intrastromal femtosecond laser treatment for presbyopia (Intracor(®)).

PURPOSE: To evaluate anatomic appearance and corneal cellular modifications after monocular Intracor(®) procedure with two different anterior segment imaging techniques within the first postoperative year. PATIENTS AND METHODS: Four patients underwent an Intracor(®) procedure in one eye performed at Clinique de la vision, and corneal imaging was performed in Quinze-Vingts National Ophthalmology Hospital. Slit-lamp photography, confocal microscopy with Heidelberg retinal tomography (HRT) and anterior segment spectral-domain optical coherence tomography (OCT) were performed 2 days, and 1, 6, and 12 months after the procedure. RESULTS: Confocal microscopy showed strong cellular activation of keratocytes within the first postoperative month which diminished over time. The linear femtosecond incisions appeared as hyper-reflective regular lines and reflectivity decreased throughout the follow-up period. After 6 months, a fibrotic process with appearance of corneal scars was visible as small intrastromal hyper-reflective lines and thick hyper-reflective spicules around the incisions and remained stable over time. On spectral-domain OCT, the size and depth of the incisions decreased from the center to the periphery. Visibility of the corneal femtosecond incisions on OCT decreased from day 2 until they almost disappeared at 12 months. The incision angles seemed to curve progressively from the center to the periphery in their deep portion on the peripheral rings. CONCLUSION: Corneal cellular modifications found on HRT, anatomical features, and the sizes of the intrastromal rings, may provide valuable information on this new refractive technique.

[Annular keratopigmentation (PresbyRing®) for treating presbyopia: postmortem animal feasibility study]. / La kératopigmentation annulaire (ou PresbyRing®) dans la prise en charge de la presbytie: étude expérimentale de faisabilité post-mortem chez l'animal.

INTRODUCTION: Annular keratopigmentation (PresbyRing(®)) is a new technique which creates an intrastromal ring centered on the visual axis, using a femtosecond laser, into which a black or a colored pigment is then injected. The internal diameter of the ring is dimensioned so as to create a pinhole and improve the near and intermediate vision of the non-dominant eye while only slightly altering the distance vision of that eye. MATERIAL AND METHODS: We used five pig eyes for our postmortem feasibility study; all five were treated with the Intra Corneal Ring program (ICR(®)) of the Visumax(®) laser. The dye used (Biochromaderm(®)) has EU approval. RESULTS: Spectral domain OCT examinations demonstrate complete opacity of the dye. Histological analysis with hematoxylin and eosin stain highlights a continuous pigmented layer located along the incision, which does not diffuse in the adjacent stroma. The possibility of rinsing the dye must be confirmed by future in-vivo animal studies. CONCLUSION: To our knowledge, this study represents the first experimental attempt to combine two ideas which did not appear to have anything in common: the creation of an intracorneal pinhole to treat presbyopia, and corneal tattooing. The first postmortem feasibility study in animals for annular keratopigmentation (PresbyRing(®)) gave encouraging results. It must be confirmed by in vivo animal studies, and ultimately in humans.

[Intrastromal femtosecond laser-based presbyopia correction]. / Intrastromale Presbyopiekorrektur mittels Femtosekundenlaser.

The surgical correction of presbyopia is gaining more and more popularity in the field of refractive surgery. Besides intraocular treatment with multifocal or accommodative intraocular lenses more and more corneal laser approaches are being established. These are performed either with the Excimer laser as laser in situ keratomileusis (LASIK) or the femtosecond laser. The femtosecond laser treatment is done purely intrastromally without dissection of the epithelium and is characterized by an extremely low risk of infection and inflammation. The procedure leads to a central corneal steepening with more prolate shape and increase in depth of field. This leads to a better uncorrected near visual acuity, however, corrected distance visual acuity might be reduced due to these changes.

Effect of multizone refractive multifocal contact lenses on the Cirrus HD OCT retinal measurements.

BACKGROUND: Simultaneous vision multifocal contact lenses are widely used to alleviate the symptoms of presbyopia. These contact lenses create simultaneous retinal images due to the incoming light distribution being divided into two or more focuses. Our aim was to evaluate whether the multizone refractive multifocal contact lenses affect the measurements of the retinal nerve fibre layer (RNFL) and macular thickness using optical coherence tomography (OCT). METHODS: In this cross-over study, 30 eyes of 30 subjects with a mean age of 50.42 ± 7.82 years were fitted with multizone refractive multifocal contact lenses. Using the RNFL Thickness Analysis mode of the Cirrus HD (Carl Zeiss, Meditec, Dublin, CA, USA) OCT, the average, superior, nasal, inferior, temporal and 12 o'clock-hour retinal nerve fibre layer thicknesses were obtained. In Macular Thickness Analysis mode of Cirrus HD OCT, the average cube thickness, macular cube volume, central subfield thickness, inner and outer macular thickness (superior, inferior, nasal and temporal area) were obtained. Measurements were performed with and without contact lenses. RESULTS: Statistically significant differences were not found in RNFL thickness at any of the studied areas and for 12 o'clock-hour sectors analysed (p > 0.07). The mean macular volume was 9.86 ± 0.30 mm(3) and 9.87 ± 0.27 mm(3) with and without multifocal contact lenses, respectively (p = 0.38). There were no statistically significant differences in average macular thickness or macular thickness of areas analysed between the measurements with and without multifocal contact lenses (p > 0.09). The signal strength was higher than seven for all scans, and differences were not found in the mean of signal strength between the measurements with and without contact lenses. CONCLUSIONS: The results of this study suggest that the assessed multizone refractive multifocal contact lens does not affect the retinal nerve fibre layer and macular thickness measurements using Cirrus HD OCT.

Peripheral optics with bifocal soft and corneal reshaping contact lenses.

PURPOSE: To determine whether bifocal soft contact lenses with a distance center design provide myopic defocus to the peripheral retina similar to corneal reshaping contact lenses. METHODS: Myopic subjects underwent five cycloplegic autorefraction readings centrally and at 10, 20, and 30 degrees temporally, nasally, superiorly, and inferiorly while wearing Proclear Multifocal "D" contact lenses with a +2.00-diopter add power (CooperVision, Fairport, NY) and after wearing Corneal Refractive Therapy (Paragon Vision Sciences, Mesa, AZ) contact lenses for 2 weeks. RESULTS: Fourteen subjects completed the study. Nine (64%) were female, and 12 (86%) were white. The average (± SD) spherical equivalent noncycloplegic manifest refraction for the right eye was -2.84 ± 1.29 diopters. The average logMAR best-corrected, binocular, high-contrast visual acuity was -0.17 ± 0.15 while wearing the bifocal soft contact lenses and -0.09 ± 0.16 after corneal reshaping contact lens wear (analysis of variance, p = 0.27). The orthokeratology contact lens yielded a more myopic peripheral optical profile than the soft bifocal contact lens at 20 and 30 degrees eccentricity (except inferior at 20 degrees); the two modalities were similar at 10 degrees eccentricity. CONCLUSIONS: Our data suggest that the two modalities are dissimilar despite the statistical similarities. The corneal reshaping contact lens shows an increase in relative peripheral myopic refraction, a pattern achieved by other studies, but the bifocal lens does not exhibit such a pattern. The low statistical power of the study could be a reason for lack of providing statistical difference in other positions of gaze, but the graphical representation of the data shows a marked difference in the peripheral optical profile between the two modalities. More sophisticated methods of measuring the peripheral optical profile may be necessary to accurately compare the two modalities and to determine the true optical effect of the bifocal soft contact lens on the peripheral retina.

Growth of the human lens in the Indian adult population: preliminary observations.

CONTEXT: The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia. AIMS: To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights. SETTINGS AND DESIGN: The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective. MATERIALS AND METHODS: Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens. STATISTICAL ANALYSIS USED: Lens parameters were analyzed as a function of age using linear and logarithmic regression methods. RESULTS: Data were obtained for 251 lenses, aged 16-93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time. CONCLUSIONS: Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

[Effect of intrastromal correction of presbyopia with femtosecond laser (INTRACOR) on mesopic contrast sensitivity]. / Auswirkungen intrastromaler Presbyopiebehandlung mittels Femtosekundenlaser (INTRACOR) auf die mesopische Kontrastsensitivität.

BACKGROUND: The aim of this study was to examine the mesopic contrast sensitivity (CS) and glare sensitivity following intrastromal femtosecond laser correction of presbyopia (INTRACOR). PATIENTS AND METHODS: In this study 25 patients with slight hyperopia and presbyopia underwent femtosecond laser correction in the non-dominant eye. Mesotest II measurements (OCULUS Optikgeräte, Wetzlar, Germany) were performed with and without glare at each of four different contrast levels preoperatively as well as 3, 6, 12, 18 and 24 months postoperatively. Data were compared using the Wilcoxon-test with a level of significance of p < 0.05. RESULTS: After 24 months the median CS decreased from 1:2 to 1:2.7 without glare and from 1:23 to 0 with glare. Of all patients 36% showed loss in CS without and 52% with glare and CS did not show any statistically significant differences between the treated and the untreated fellow eyes after 12 and 24 months. Overall 9 out of 18 monocular treated patients showed no binocular night driving ability according to the recommendations of the German Society of Ophthalmology (DOG) and the Professional Association of German Ophthalmologists (BVA) 24 months following INTRACOR. CONCLUSIONS: INTRACOR can lead to a slight reduction of mesopic contrast sensitivity and an increase of glare sensitivity. Possible consequences on night driving ability should be discussed with the patients prior to treatment.

The interpupillary distance in adult Caucasian subjects, with reference to 'readymade' reading spectacle centration.

PURPOSE: The magnitude of the far interpupillary distance (FIPD) has recognized significance within and beyond clinical optometry. Quantitative information regarding the lesser-reported near parameter (NIPD) would similarly be of interest, and could be of relevance with regard to the visual comfort obtained with 'readymade' reading spectacles. METHODS: Mensuration statistics relating to the FIPD and NIPD are presented, as collated from the spectacle dispensing records of n = 1354 healthy Caucasian presbyopic subjects. The FIPD data were partitioned across 4 age bands (by decade, 41-80 years of age): the NIPD data were distributed across seven nominal reading powers (in 0.50 D steps, +1.00 to +4.00 D). The results of these analyses are considered here, along with their potential application. RESULTS: Consistent gender (male > female) and classification (far > near) differences in IPD (both of approximately 3 mm) were confirmed throughout these data. The magnitude of the adult FIPD is in accord with previously published results; this dimension is now supplemented by NIPD values, whose relationship with total near power is also described. CONCLUSIONS: This new anthropometric survey indicates that inter- and intra-gender interocular facial measurement stability is a characteristic of presbyopic subjects. It is suggested that across the anticipated range of age and total reading power requirement of Caucasian (White Northern European) wearers of 'readymade' reading spectacles, adoption of a standard optical centration distance of 61 mm would be universally appropriate.