Simultaneous Vision Research Articles

One-Year Experience in Presbyopia Correction With Biaspheric Multifocal Central Presbyopia Laser In Situ Keratomileusis

To analyze simultaneous vision (distance and near) 1-year after biaspheric multifocal central presbyLASIK treatments for hyperopia and myopia with or without astigmatism. Patients were treated to correct distance ametropias and alleviating presbyopic symptoms simultaneously. All patients have been treated in Presby aberration-free mode using FemtoLASIK for Sphere from -7.00 to +3.25 diopters (D), astigmatism up to 3.00 D, and addition up to +2.75 D. No eye had previous corneal refractive surgery. Preoperative corneal curvature ranged between 40 and 48 D, with pachymetry thicker than 500 μm. Preoperative corrected distance visual acuity was 0.1 logarithm of the minimum angle of resolution (logMAR) or better, with near vision of 0.2 logRAD or better with addition up to +2.50 D. Sixty-six eyes treated bilaterally using PresbyMAX software were reviewed. For 31 patients (94%), 1-year follow-up was completed. At 1 year, 70% of patients achieved uncorrected distance visual acuity 0.1 logMAR or better, 84% patients obtained uncorrected near visual acuity 0.1 logRAD or better, and 83% of eyes were within 0.75 D of defocus. Postoperative mean spherical equivalent refraction was -0.47 ± 0.44 D. Stability was achieved from the 6-week follow-up. Eighty-five percent of patients achieved simultaneously uncorrected distance visual acuity 0.2 logMAR or better and uncorrected near visual acuity 0.2 logRAD or better. Patient selection and expectation management is essential to achieve patient satisfaction. Even though optically the results are predictable and good, some patients find it difficult to adapt to the compromise and others are dissatisfied by the minor loss of distance visual acuity. Certain individuals are best suited for PresbyMAX. A test with multifocal contact lenses or trial frames that creates slightly defocused images can be used to simulate postoperative visual impressions and verify patient acceptance.

Application of Hybrid Vision Method for the Hot Aluminium Surface Inspection

The paper presents the possibilities of a hybrid vision method based on simultaneous analysis of infrared and vision images for surface inspection of hot aluminium in a manufacturing process. The system consists of a NIR/SWIR camera and a high resolution visual camera, and a computer based image analysis system. The simultaneous analysis of infrared and vision images will enable surface inspection for detecting defects in temperature range from 200°C to 600°C. Thermal images present temperature distribution on the surface, and contain information about the manufacturing process. The analysis of thermograms enables to find areas of temperature irregularity caused by increased friction loads, as well as areas of inhomogeneous emissivity caused by surface defects. Furthermore, information captured by the vision camera is used to detect surface defects. The software developed enables the overlaying of images. The proposed simultaneous thermovision and vision imaging can be applied in industry for in-line monitoring of aluminium extrusion processes.

Experimental Simulation of Simultaneous Vision

To present and validate a prototype of an optical instrument that allows experimental simulation of pure bifocal vision. To evaluate the influence of different power additions on image contrast and visual acuity. The instrument provides the eye with two superimposed images, aligned and with the same magnification, but with different defocus states. Subjects looking through the instrument are able to experience pure simultaneous vision, with adjustable refractive correction and addition power. The instrument is used to investigate the impact of the amount of addition of an ideal bifocal simultaneous vision correction, both on image contrast and on visual performance. the instrument is validated through computer simulations of the letter contrast and by equivalent optical experiments with an artificial eye (camera). Visual acuity (VA) was measured in four subjects (AGE: 34.3 ± 3.4 years; spherical error: -2.1 ± 2.7 diopters [D]) for low and high contrast letters and different amounts of addition. The largest degradation in contrast and visual acuity (∼25%) occurred for additions around ±2 D, while additions of ±4 D produced lower degradation (14%). Low additions (1-2 D) result in lower VA than high additions (3-4 D). A simultaneous vision instrument is an excellent tool to simulate bifocal vision and to gain understanding of multifocal solutions for presbyopia. Simultaneous vision induces a pattern of visual performance degradation, which is well predicted by the degradation found in image quality. Neural effects, claimed to be crucial in the patients' tolerance of simultaneous vision, can be therefore compared with pure optical effects.

Visual performance comparison between contact lens‐based pinhole and simultaneous vision contact lenses

BackgroundThe aim was to evaluate the visual performance provided with a contact lens‐based pinhole design against a simultaneous vision multifocal contact lens.MethodsIn a cross‐over study at the University of Valencia, 22 presbyopic patients were evaluated using an artificial pupil fitted on the non‐dominant eye and the simultaneous vision PureVision Multifocal contact lenses. After one month of contact lens wear, binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance contrast sensitivity, binocular near contrast sensitivity, and stereoacuity were measured, under photopic conditions (85-cd/m2). In addition, binocular distance visual acuity and binocular distance contrast sensitivity were examined under mesopic conditions (5-cd/m2).ResultsMean binocular distance visual acuity for pinhole and PureVision Multifocal were 0.02 ± 0.04 and 0.01 ± 0.04 logMAR under photopic conditions and 0.16 ± 0.06 and 0.12 ± 0.04 logMAR for binocular near visual acuity under mesopic conditions, respectively. No statistically significant differences were found between both types of lenses at distance for both lighting levels and intermediate distances (p > 0.05). There was a significant difference at near vision under photopic conditions (p = 0.03). Binocular distance contrast sensitivity revealed statistically significant differences between the pinhole system and PureVision Multifocal for six and 12-cpd (cycles per degree) spatial frequencies at the two luminance levels, while for near vision, differences were also significant for 18-cpd. Stereoacuity was better with PureVision Multifocal (127 ± 49.3 seconds of arc) compared with the pinhole lens (220.2 ± 32.3 seconds of arc, p = 0.004).ConclusionPinhole and PureVision Multifocal contact lenses provide good binocular vision for distance and functional intermediate vision. Although it was better with the PureVision Multifocal, near vision was not satisfactory for either of the two contact lens options.

Visual performance of two simultaneous vision multifocal contact lenses

To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs). In this cross-over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CLs (the PureVision Multifocal Low Add and Acuvue Oasys for Presbyopia) in random order. After 1 month, binocular distance visual acuity (BDVA) under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) conditions, binocular near visual acuity (BNVA), binocular distance contrast sensitivity function (CSF) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the procedure was repeated. Mean BDVA under photopic conditions was similar for the Acuvue Oasys for Presbyopia and PureVision Multifocal Low Add: 0.01 ± 0.08 and 0.00 ± 0.08 logMAR, respectively (P = 0.45). Under mesopic conditions the values of BDVA were 0.20 ± 0.58 and 0.11 ± 0.09 logMAR, respectively (P = 0.005). Mean BNVA was 0.20 ± 0.05 and 0.15 ± 0.08 logMAR for the Acuvue Oasys and PureVision Low Add, respectively (P = 0.06). Binocular distance CSF testing revealed no statistically significant differences between lenses under photopic, mesopic or near conditions. Both lenses provided a comparable intermediate visual acuity. Both simultaneous vision multifocal CLs provided adequate distance visual quality under photopic and mesopic conditions, and better visual acuity was provided under mesopic conditions for the Purevision lens. Both lenses provided adequate visual performance at intermediate distance, but the near visual acuity appears to be insufficient for early presbyopes who require a moderately demanding near visual quality.

Concurrent Vision Dysfunctions in Convergence Insufficiency With Traumatic Brain Injury

This study assessed the prevalence of convergence insufficiency (CI) with and without simultaneous vision dysfunctions within the traumatic brain injury (TBI) sample population because although CI is commonly reported with TBI, the prevalence of concurrent visual dysfunctions with CI in TBI is unknown. A retrospective analysis of 557 medical records from TBI civilian patients was conducted. Patients were all evaluated by a single optometrist. Visual acuity, oculomotor function, binocular vision function, accommodation, visual fields, ocular health, and vestibular function were assessed. Statistical comparisons between the CI and non-CI, as well as inpatient and outpatient subgroups, were conducted using χ and Z tests. Approximately 9% of the TBI sample had CI without the following simultaneous diagnoses: saccade or pursuit dysfunction; third, fourth, or sixth cranial nerve palsy; visual field deficit; visual spatial inattention/neglect; vestibular dysfunction; or nystagmus. Photophobia with CI was observed in 16.3% (21 of 130), and vestibular dysfunction with CI was observed in 18.5% (24 of 130) of the CI subgroup. Convergence insufficiency and cranial nerve palsies were common and yielded prevalence rates of 23.3% (130 of 557) and 26.9% (150 of 557), respectively, within the TBI sample. Accommodative dysfunction was common within the nonpresbyopic TBI sample, with a prevalence of 24.4% (76 of 314). Visual field deficits or unilateral visual spatial inattention/neglect was observed within 29.6% (80 of 270) of the TBI inpatient subgroup and was significantly more prevalent compared with that of the outpatient subgroup (p < 0.001). Most TBI patients had visual acuities of 20/60 or better in the TBI sample (85%; 473 of 557). Convergence insufficiency without simultaneous visual or vestibular dysfunctions was observed in about 9% of the visually symptomatic TBI civilian population studied. A thorough visual and vestibular examination is recommended for all TBI patients.

Changes in Accommodation and Ocular Aberration With Simultaneous Vision Multifocal Contact Lenses

The aim of this study was to evaluate ocular aberration changes through different simultaneous vision multifocal contact lenses (CLs). Eighteen young-adult subjects with a mean age of 29.8±2.11 years took part. Changes in accommodative response, spherical aberration (C(4)(0)), horizontal coma (C(3)(1)), vertical coma (C(3)(-1)), and root mean square (RMS) of higher-order aberrations (HOAs, third to sixth orders) were evaluated. Measurements were obtained with a distance-single vision CL and 2 aspheric multifocal CLs of simultaneous focus center-near design (PureVision Low Add and PureVision High Add) for 2 accommodative stimuli (-2.50 and -4.00 D). All measurements were performed monocularly with a Hartmann-Shack aberrometer (IRX-3; Imagine Eyes, Orsay, France). No statistically significant differences were found in accommodative responses to -2.50- and -4.00-D stimuli between the single vision CL and the 2 multifocal CLs. Spherical aberration was found to decrease and become more negative with accommodation for both stimuli with all three CLs. Horizontal coma decreased significantly with accommodation (-2.5- and -4.00-D stimuli) for the distance-single vision CLs (P=0.002 and P=0.003). No differences were found in vertical coma Zernike coefficients. The RMS of HOAs was found to decrease only with the single vision CLs for both stimuli (P<0.01). Data obtained in this study suggest that in young subjects, the multifocal CLs studied do not induce large changes in accommodative response compared with the distance-single vision CLs. Spherical aberration reduced significantly with accommodation.

3-Month experience in presbyopic correction with bi-aspheric multifocal central presbyLASIK treatments for hyperopia and myopia with or without astigmatism

PurposeTo analyze simultaneous vision (distance and near) 3-month after bi-aspheric multifocal central presbyLASIK treatments for hyperopia and myopia with or without astigmatism. MethodsRetrospective study analyzing patients that had been treated for correcting distance ametropiae and alleviating presbyopic symptoms simultaneously. All patients had been treated in Presby Aspheric mode using FemtoLASIK. No eye had previous corneal refractive surgery. Preoperative corneal curvature ranged between 40D and 48D, with pachymetry thicker than 500μm. Preoperative best distance corrected visual acuity (CDVA) was 0.1 LogMAR or better, with best corrected near vision (CNVA) of 0.2 LogRAD or better. Results66 patients treated using PresbyMAX software (SCHWIND eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany) were reviewed. For 24 patients, 3-month follow-up was completed. At 3 months, 71% of patients achieved UDVA 0.1 LogMAR or better, 79% patients obtained UNVA 0.1 LogRAD or better, and 83% of eyes were within 0.75 diopters (D) of defocus. Postoperative mean spherical equivalent refraction was −0.15±0.50D. Stability was achieved from the 6-week follow-up. 92% of patients achieved UDVA 0.2 LogMAR or better and UNVA 0.2 LogRAD or better. No statistical differences between myopes/hyperopes or between males/females were found. ConclusionsPatient selection and expectation management are essential to achieve patient satisfaction. Even though optically the results are quite predictable, some patients find it difficult to adapt to the compromise between far and near vision, and others are dissatisfied by the minor loss of distance VA.

Sequential vs simultaneous encoding of spatial information: A comparison between the blind and the sighted

The aim of this research is to assess whether the crucial factor in determining the characteristics of blind people's spatial mental images is concerned with the visual impairment per se or the processing style that the dominant perceptual modalities used to acquire spatial information impose, i.e. simultaneous (vision) vs sequential (kinaesthesis). Participants were asked to learn six positions in a large parking area via movement alone (congenitally blind, adventitiously blind, blindfolded sighted) or with vision plus movement (simultaneous sighted, sequential sighted), and then to mentally scan between positions in the path. The crucial manipulation concerned the sequential sighted group. Their visual exploration was made sequential by putting visual obstacles within the pathway in such a way that they could not see simultaneously the positions along the pathway. The results revealed a significant time/distance linear relation in all tested groups. However, the linear component was lower in sequential sighted and blind participants, especially congenital. Sequential sighted and congenitally blind participants showed an almost overlapping performance. Differences between groups became evident when mentally scanning farther distances (more than 5m). This threshold effect could be revealing of processing limitations due to the need of integrating and updating spatial information. Overall, the results suggest that the characteristics of the processing style rather than the visual impairment per se affect blind people's spatial mental images.

Accommodative Functions with Multifocal Contact Lenses: A Pilot Study

To evaluate accommodative response and facility in presbyopic patients fitted with several types of simultaneous-image multifocal contact lenses (CLs). Six presbyopic patients, unadapted wearers of simultaneous-image bifocals, were fitted with the Focus Progressives and the low- and high-addition Pure Vision simultaneous vision multifocal CLs. Each individual wore each of the three types of lenses in successive random order. Accommodative response, accommodative facility, visual acuity, and contrast sensitivity at distance and near were evaluated in all cases. A control group of eight non-presbyopic patients was also studied. The mean age was 28.6 ± 2.72 and 51.2 ± 5.81 years in the non-presbyopes and presbyopic patients, respectively. For the presbyopic group, statistically significant differences were not found for distance visual acuity between the baseline situations and with the three different CLs types. For the near visual acuity, there were no statistically significant differences between baseline situation (without add) compared with patients wearing the Focus Progressives and with PureVision Low Add. With the Purevision High Add, the near visual acuity was slightly better than baseline situation (p = 0.03). Non-presbyopic subjects showed relatively linear 1:1 stimulus response functions for all situations. Presbyopic subjects showed an increasing lag of accommodation with amplitude as they approach to the maximum amplitude for all situations. Distance and near accommodative facility rate for the presbyopic patients was zero for all conditions. The results of this study suggest that simultaneous-image multifocal CLs studied do not alter accommodative functions. The high add of the Purevision CL enhances near vision for advanced presbyopes compared with the other models studied.

In the four-eyed fish ( Anableps anableps ), the regions of the retina exposed to aquatic and aerial light do not express the same set of opsin genes

The four-eyed fish, Anableps anableps, has eyes with unusual morphological adaptations for simultaneous vision above and below water. The retina, for example, is divided such that one region receives light from the aerial field and the other from the aquatic field. To understand better the adaptive value of this partitioned retina, we characterized photoreceptor distribution using in situ hybridization. Cones expressing sws1, sws2b and rh2-2 (i.e. UV, and short wavelength-sensitive) opsins were found throughout the retina, whereas cones expressing rh2-1 (middle wavelength-sensitive) were largely limited to the ventral retina and those expressing lws (long wavelength-sensitive) opsins were only expressed in the dorsal retina. We next asked when this pattern evolved relative to the 'four-eyed' morphology. We characterized opsin expression in Jenynsia onca, a member of the sister genus to Anableps with typical teleost eye morphology. In J. onca, sws1, sws2b, rh2-2 and rh2-1 opsins were expressed throughout the retina; while lws opsins were not expressed in the ventral retina. Thus, the change that coincides with the evolution of unusual anablepid eye morphology is the loss of rh2-1 expression in the dorsal retina, probably to accommodate increased lws opsin expression. The retinal area that samples aerial light appears not to have changed with respect to photoreceptor transcription.

Task oriented visual satisfaction and wearing success with two different simultaneous vision multifocal soft contact lenses

Purpose A longitudinal prospective, cross-over, double masked study was designed to evaluate task oriented visual satisfaction and wearing success with two types of simultaneous vision multifocal soft contact lenses. Methods Twenty-two presbyopic subjects followed two 14-day trial periods in which they were alternatively and randomly fitted with two types of multifocal lenses. Habitual tasks were described in terms of observation distance, visual demand level and time allocation. Subjects graded visual satisfaction with each pair of lenses and each habitual task at different times during each trial. Overall satisfaction was evaluated after completion of the two trial periods. Wearing success was determined by the percentage of subjects opting to continue multifocal lens wear and by the number of subjects still wearing their lenses six months later. Results Viewing distance and visual demand level were found to influence visual satisfaction (p < 0.001). Visual satisfaction decreased for tasks involving higher visual demands and for near and far viewing distances, rather than for intermediate vision or a combination of near and far vision. A combined effect of lens type and evaluation time was discovered (p = 0.046). Although 78% of subjects decided to continue lens wear, only one subject was wearing them on a daily basis 6 months after the completion of the study. Insufficient quality of vision was reported as the main reason for multifocal contact lens discontinuation. Conclusions A task oriented visual satisfaction evaluation may prove helpful in lens design selection, as well as in predicting wearing success.

Stereoacuity with balanced presbyopic contact lenses

Background: To evaluate near stereoacuity with the balanced Proclear Multifocal simultaneous vision contact lens.Methods: Twenty‐five presbyopic subjects were fitted binocularly with the Proclear Multifocal contact lens and with distance contact lenses combined with reading spectacles, which served as controls. After one month, stereoacuity was measured using the vectographic Titmus and Random dot stereotests and the Howard‐Dolman (HD) apparatus under photopic conditions (85-cd/m2) at 40-cm. Binocular high‐contrast visual acuities (BHCVA) at distance and near were examined.Results: For the multifocal group, mean stereoacuity with the Howard‐Dolman method was 22.40 ± 8.23 seconds of arc. Using the Titmus and the Random dot sterereotests, the values were 56.40 ± 18.00 and 54.80 ± 20.23 seconds of arc, respectively. For the SCL group, mean stereoacuities were 19.9 ± 4.6, 51.2 ± 16.4 and 51.2 ± 20.88 seconds of arc, with the Howard‐Dolman, Titmus and the Random dot, respectively. There were no statistically significant differences among groups for Howard‐Dolman (p = 0.07), Titmus (p = 0.10) and Random dot (p = 0.17) stereotests. No statistically significant differences were found between the Titmus and the Random dot stereotest values (multifocal group: p = 0.30 and SCL group: p = 0.50), however, these values differ significantly from those found using the Howard‐Dolman method for both groups (p < 0.001). For the multifocal group, BHCVA was −0.007 ± 0.060 and 0.012 ± 0.063 logMAR for distance and near vision, respectively. For the SCL group, these values were −0.02 ± 0.05 and −0.01 ± 0.06 logMAR, for distance and near vision, respectively. Comparing both groups there were no statistically significant differences between groups for either distance (p = 0.08) or near (p = 0.09).Conclusions: The Proclear Multifocal contact lens provided good distance and near visual acuity preserving stereopsis. Multifocal optics with one lens biased to distance viewing and the other lens biased toward near viewing minimally affects stereoacuity.

To the Editor: Stereoacuity with Simultaneous Vision Multifocal Contact Lenses

Optometry and Vision Science: December 2010 - Volume 87 - Issue 12 - p 1057 doi: 10.1097/OPX.0b013e31820504b7

Inherent Ocular Spherical Aberration and Multifocal Contact Lens Optical Performance

The role of inherent spherical aberration (SA) in the optical performance of presbyopic eyes corrected with simultaneous vision multifocal contact lenses was investigated. Presbyopic schematic eyes were modeled with partial accommodative function to represent 45- and 55-year olds and were further classified into five categories based on their magnitude of inherent SA. Two representative ametropic models of each category were corrected with four multifocal contact lens iterations. High-add designs were used to correct 55-year olds, whereas low-add designs served 45-year ones. The overall performances were gauged in terms of visual Strehl ratio and area under through-focus modulation transfer function. The root mean square error of higher order aberrations of the eye and correcting lens combination were significantly different (p < 0.05) within the five inherent SA models, for all pupils and accommodative states. Area under through-focus modulation transfer function at all three spatial frequencies tested was found to be significantly different (p < 0.05) within the five SA models. Visual Strehl ratio measures were also different but statistically insignificant. Eyes having the same refractive prescriptions but diverse levels of inherent SA perform differently even when corrected with identical multifocal designs, and the performance is dependent on pupil size and level of residual accommodation. Overall, the distinct performances within the five SA models were optically relevant for pupils ∼4 mm and greater. Among the designs investigated, the low-add multizone iteration demonstrated performance relatively independent of the inherent SA because of the favorable interactions of defocus with primary, secondary, and tertiary SA. These findings confirm that the coupling of ocular SA and correcting lens aberrations contributes to the multifocal functionality.

Aspheric Wavefront-guided LASIK to Treat Hyperopic Presbyopia: 12-Month Results With the VISX Platform

To evaluate an aspheric ablation profile to improve near vision in presbyopic patients with hyperopia and to outline the key factors of success. A prospective, nonrandomized, clinical trial of 66 eyes of 33 hyperopic patients who underwent customized bilateral refractive surgery, which included an aspheric presbyopia treatment shape and wavefront-driven hyperopic treatment, was studied. Surgeries were performed using the VISX STAR S4 or STAR S4 IR excimer laser system (Abbott Medical Optics). Mean preoperative refractive error was +1.77 ± 0.56 diopters (D) sphere (range: 0.75 to 3.50 D) with 0.41 ± 0.34 D cylinder (range: 0.00 to 1.50 D). All patients received full distance refractive correction. No patients received monovision or were intentionally left with residual myopia. Patient satisfaction results were evaluated using a questionnaire with a 5-point scale. Sixty eyes completed 6-month and 50 eyes completed 12-month postoperative follow-up. At 6 months, mean corrected distance visual acuity (CDVA) was 20/20±1 line (range: 20/25 to 20/10). Mean gain in distance-corrected near visual acuity (DCNVA) was 2.7 ± 1.7 lines with a maximum of 6 lines of near. Spectacle dependence for tasks, such as reading and computer use, was reduced. At 12 months, 100% of patients had achieved binocular simultaneous uncorrected vision of 20/25 or better and J3. Refraction was stable over 12 months. Contrast sensitivity reduction was clinically insignificant (1 step or 0.15 logCS). Negative spherical aberration highly correlated with postoperative improvement of DCNVA. Patients who had a larger amount of preoperative hyperopia or a greater decrease of preoperative DCNVA were more likely to have overall satisfaction. The aspheric ablation designed to expand near functional vision was effective and stable over 12 months. The wavefront-customized hyperopic treatment significantly reduced spectacle dependence.

Gas permeable lenses are alive and well in 2010

Gas permeable lenses are alive and well in 2010

Stereoacuity with Simultaneous Vision Multifocal Contact Lenses

To evaluate near stereoacuity (SA) with Focus Progressives and PureVision Multifocal simultaneous vision contact lenses. In a cross-over study design, 20 presbyopic subjects were fitted with either the Focus Progressives or PureVision Multifocal lenses. After 1 month, SA was measured with the vectographic Titmus, Random dot stereotests, and the Howard-Dolman apparatus under photopic conditions (85 lux) at 40 cm. Binocular high-contrast visual acuity at distance and near was examined. Subjects were then refitted with the alternative correction and the procedure was repeated. Mean SA with the Focus Progressive was 21 +/- 7 sec arc, 54 +/- 17 sec arc, and 51 +/- 21 sec arc, with the Howard-Dolman, Titmus, and Random dot sterereotests, respectively. These values were 25 +/- 9 sec arc, 74 +/- 26 sec arc, and 82 +/- 26 sec arc with the PureVision Multifocal, respectively. SA was better with the Focus Progressives compared with the PureVision using the Howard-Dolman (4 sec arc of difference; p = 0.001), Titmus (2 sec arc of difference; p = 0.001), and Random dot (31 sec arc of difference; p < 0.001) tests. Binocular mean high-contrast distance visual acuity was similar for the Focus Progressives and PureVision Multifocal: -0.01 +/- 0.07 and +0.02 +/- 0.08 logMAR, respectively (p = 0.074). At near vision, these values were +0.01 +/- 0.07 and +0.06 +/- 0.06 logMAR, respectively, being statistically significant different (p = 0.004). Both the Focus Progressive and PureVision Multifocal contact lenses provided good visual acuity preserving stereopsis. Focus Progressives had slightly better near acuity and better SA than the Purevision Multifocal contact lenses. Differences found between the lens types may be related to asphericity, near addition of the contact lens, or even visual acuity differences between the two eyes that were not measured in this study but could conceivably have contributed to SA measure differences. SA measurement with a Howard-Dolman apparatus reveals better SA than vectographic tests.

A behavioural method for evaluating depth of focus

Abstract Purpose To develop a technique based on visual reaction times that can evaluate the depth of focus in uncorrected vision or when using different modalities of simultaneous vision correction for presbyopia. Reaction Times (RTs) are known to increase in a predictable way as stimuli become less visible, i.e. as contrast decreases. Contrast reduction, produced by different amounts of defocus blur, was calculated by increased RT. Methods RTs were measured to the onset of a sinusoidal grating with a spatial frequency of 4 c/deg and a contrast of 10%, displayed on a Sony F‐520 CRT monitor (mean luminance 30 cd/m2), using a VSG2/5 stimulus generator card. All measurements were performed monocularly (dominant eye) and binocularly at 3m viewing distance, with best spectacle sphero‐cylindrical correction for distance and natural pupils. RTs were measured for different degrees of blur, induced using positive powered lenses up to +4.50 D. Results RT increased with defocus blur, with the effect being more pronounced for monocular compared to binocular viewing conditions. Depth of acceptable perceptual blur (depth of focus) was calculated from the second order polynomials, which fitted the RT vs. defocus blur functions. More specifically, the width of the polynomial fit was estimated for a specific RT. Regardless of the criterion chosen, the depth of acceptable blur was greater under binocular to monocular viewing. Conclusion The technique described here offers a behavioural measure of the depth of focus, and allows evaluation under both monocular / binocular viewing conditions.

LASIK Correction of Vision in Adults with Unilateral Amblyopia

to evaluate the effects of laser refractive surgery in adult patients with mild to moderate amblyopia due to anisometropic myopia. a retrospective review of 30 patients (60 eyes) with unilateral amblyopia (corrected distance visual acuity [CDVA] 0.6 or worse) who underwent simultaneous bilateral laser vision correction using the Technolas 217z excimer laser (Bausch & Lomb) was performed. Mean patient age was 31.03 ± 10.05 years (range: 18 to 53 years). Visual outcomes in the amblyopic eye were compared with those in the fellow nonamblyopic control eye of the same patient. mean preoperative CDVA improved in amblyopic eyes from 0.50 ± 0.13 to 0.57 ± 0.20 postoperatively (average gain of 0.075 ± 0.14; P=.007) and improved from 0.92 ± 0.12 preoperatively to 0.93±0.15 after surgery (mean gain of 0.013 ± 0.14; P=.603) in the fellow nonamblyopic eyes. The safety index was significantly greater in the amblyopic eyes compared with the nonamblyopic fellow eyes (1.15 ± 0.30 vs 1.02 ± 0.15, P=.035), therefore, no difference was noted in efficacy (P=.913). Five of 30 eyes with mild to moderate amblyopia gained 2 to 4 lines of CDVA. laser refractive surgery for myopic correction was found to be safe and effective in eyes with mild to moderate amblyopia.