Subjective Visual Acuity Research Articles

A Prospective Study of Pterygium Excision and Conjunctival Autograft With Human Fibrin Tissue Adhesive: Effects on Vision, Refraction, and Corneal Topography.

This study aimed to investigate changes in visual acuity, corneal parameters, and topographic parameters after pterygium surgery. A prospective observational study was conducted. Twenty eyes of 20 participants undergoing pterygium excision with conjunctival autograft secured using human fibrin tissue adhesive were included in the study. All the participants were assessed preoperatively and 1 and 3 months postoperatively. The parameters included subjective refraction, visual acuity, and pterygium size (pterygium horizontal corneal length [PHCL]) and corneal tomography by Pentacam rotating Scheimpflug tomographer (OCULUS Optikgeräte GmbH, Wetzlar, Germany). The astigmatic changes were calculated using vector analysis. The mean age of participants was 49.3 ± 12.1 years. Mean PHCL was 2.68 ± 0.30 mm. The mean best corrected visual acuity preoperatively was 6/7.5, improving significantly to 6/6 at 1 month (P = 0.001) with this improvement remaining stable at 3 months postoperatively (P = 0.34). There was no significant change in subjective astigmatism, however, mean topographic astigmatism decreased significantly at 1 month (4.36 diopter, P < 0.01) and remained unchanged at 3 months (P < 0.01). Greater PHCL was associated with greater changes in corneal astigmatism. Significant improvements and early stabilization of visual acuity and topographic astigmatism confirm the optical benefits of pterygium excision. These data also suggest a significant advantage of performing pterygium before rather than simultaneously with or after cataract surgery by enabling the most accurate biometry.

Medical Applications and Outcomes of Bitangential Scleral Lenses

To evaluate the clinical results of a new scleral lens design with a bitangential (nonrotationally symmetrical) periphery. All the necessary data were obtained during the 1-year study period. The bitangential scleral lenses were fitted and monitored according to a standardized fitting methodology. They were cut by precise submicron lathing from high-oxygen-permeable materials (including 10 scleral lenses from Menicon Z material). Subjective performance, visual acuity, and scleral lens-fitting characteristics were recorded after a median of 9.4 weeks (range, 3 weeks to 1 year). Diagnoses in the 213 eyes (in 144 patients) were keratoconus (n = 121 eyes; 56.8%), ocular surface diseases (n = 31 eyes; 14.6%), penetrating keratoplasty (n = 29 eyes; 13.6%), and other forms of irregular astigmatism (n = 28 eyes; 13.1%). Many patients (164 lenses; 77.0%) gave high ratings for comfort. The most common diameter was 20.0 mm (162 lenses; 76.1%) (range, 18.5 to 21.5 mm). Median decimal best-corrected visual acuity with the bitangential scleral lenses was 0.8 (equivalent to Snellen 20/25) (range, 0 to 1.5). Most bitangential scleral lenses showed good fitting characteristics: optimal values were seen for lens movement (208 lenses; 97.7%) and lens position (208 lenses; 97.7%). Median central corneal clearance was 0.2 mm; clearances differed in the four peripheral directions. The median stabilization axis was 140 degrees (range, 0 to 180 degrees) in the right eyes and 60 degrees (range, 0 to 180 degrees) in the left eyes. The bitangential scleral lens-fitting and performance characteristics were clear and effective for the health professional and the patient. The high-oxygen-permeable material Menicon Z may, in theory, be of benefit to corneas with a high oxygen demand.

Comparison of corneal haze and visual outcome in primary DSAEK versus DSAEK following failed DMEK

Descemet membrane endothelial keratoplasty (DMEK) is being proposed as the procedure of choice in corneal endothelial disease as it achieves better visual and refractive outcomes than Descemet stripping automated endothelial keratoplasty (DSAEK). Nevertheless, primary graft failure is frequent, especially during the learning curve, and secondary back-up procedure consists on DSAEK. We aim to compare corneal haze and visual acuity of patients undergoing primary DSAEK vs. patients undergoing DSAEK as a back-up procedure after primary DMEK failure. This study is a comparative case series that included 19 eyes from 16 patients with early stages of corneal failure and limitation of daily activities after primary DSAEK or secondary DSAEK. A control group of non-operated corneas included 10 aged-matched normal eyes. The study was conducted at University Hospital Ramón y Cajal and Vissum Hospital, Madrid, Spain. Corneal densitometry readings and postoperative best-corrected visual acuity in subjects with primary and secondary DSAEK were recorded 6 months after the surgery using the Pentacam Scheimpflug system (Oculus, inc.,Wetzlar, Germany). In primary DSAEK median densitometry values (range) were statistically significantly higher (p < 0.05) than normal subjects for the full thickness, posterior and anterior part of the paracentral cornea; and the anterior part of the central cornea. In secondary DSAEK, median densitometry values were statistically significantly higher than normal subjects at all levels of the central and paracentral cornea. In secondary DSAEK, median densitometry values (range) were statistically significantly higher than in primary DSAEK in the full-thickness, anterior part and interface of the central cornea and in the full-thickness and posterior part of the paracentral cornea. Median visual acuity between groups (p = 0.47) was statistically better for the primary DSAEK group, which also had a higher percentage of patients achieving BCVA of ≥ 20/40 and ≥ 20/25 than the secondary DSAEK group (100% vs. 62% and 60% vs. 0% respectively). There is an increase in central corneal light scattering after secondary DSAEK performed after a failed DMEK as compared to primary DSAEK. This has a negative impact on final visual acuity that needs to be considered in each patient when starting DMEK surgery.

Prospective Study of Lotrafilcon B Lenses Comparing 2 Versus 4 Weeks of Wear for Objective and Subjective Measures of Health, Comfort, and Vision

To examine potential changes in comfort, ocular health, and vision between 2 weeks and 1 month for wearers of lotrafilcon B lenses. Up to 120 current wearers of lotrafilcon B lenses were recruited to wear a new pair of lenses for 1 month, using their habitual lens care system. Subjective ratings, biomicroscopy scores, visual acuity, and lens assessments were recorded at 2 weeks and at 1 month. In addition, participants responded to 4 Likert-type statements regarding comfort and vision after the full month of wear. No significant differences were noted in biomicroscopy scores between 2 weeks and 1 month. Noninferiority from 2 weeks to 1 month was established for subjective ratings of visual clarity (P=0.003; n=112) and ocular redness (P<0.001; n=112); the other 7 subjective ratings (for comfort, dryness, etc.) decreased less than 1 unit on 10-point scales. Significant majorities of respondents (all P<0.001 vs. 50%) agreed or strongly agreed that the lenses provided excellent comfort (83.5% of respondents) and clear vision (83.5%) throughout the month and that comfort (71.5%) and vision (77.9%) were the same at the end of the month as at the beginning of the month. Two adverse events occurred during the trial. Both were asymptomatic and considered clinically insignificant. Significant majorities of patients agreed that the lenses provided consistent comfort and vision throughout the month. Most wearers of lotrafilcon B lenses did not perceive substantial deteriorations in comfort or vision over the recommended wearing interval. Outcomes support monthly replacement of these lenses.

Feasibility of a Clinical Trial of Vision Therapy for Treatment of Amblyopia

We conducted a pilot randomized clinical trial of office-based active vision therapy for the treatment of childhood amblyopia to determine the feasibility of conducting a full-scale randomized clinical trial. A training and certification program and manual of procedures were developed to certify therapists to administer a standardized vision therapy program in ophthalmology and optometry offices consisting of weekly visits for 16 weeks. Nineteen children, aged 7 to less than 13 years, with amblyopia (20/40-20/100) were randomly assigned to receive either 2 hours of daily patching with active vision therapy or 2 hours of daily patching with placebo vision therapy. Therapists in diverse practice settings were successfully trained and certified to perform standardized vision therapy in strict adherence with protocol. Subjects completed 85% of required weekly in-office vision therapy visits. Eligibility criteria based on age, visual acuity, and stereoacuity, designed to identify children able to complete a standardized vision therapy program and judged likely to benefit from this treatment, led to a high proportion of screened subjects being judged ineligible, resulting in insufficient recruitment. There were difficulties in retrieving adherence data for the computerized home therapy procedures. This study demonstrated that a 16-week treatment trial of vision therapy was feasible with respect to maintaining protocol adherence; however, recruitment under the proposed eligibility criteria, necessitated by the standardized approach to vision therapy, was not successful. A randomized clinical trial of in-office vision therapy for the treatment of amblyopia would require broadening of the eligibility criteria and improved methods to gather objective data regarding the home therapy. A more flexible approach that customizes vision therapy based on subject age, visual acuity, and stereopsis might be required to allow enrollment of a broader group of subjects.

Neodymium–Yttrium-Aluminum-Garnet Laser Lysis of Retained Cortex After Phacoemulsification Cataract Surgery

To describe the use of the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser to lyse residual cortex after phacoemulsification cataract surgery and report the complications and outcomes of treatment. Interventional, retrospective case series. Consecutive patients who underwent Nd:YAG laser treatment for residual cortex at the Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan were identified by review of laser logs from 2005 to 2011. The medical records were reviewed, and the course and complications of treatment were recorded. The main outcome measures were improvement in subjective vision and corrected distance visual acuity. Eighteen eyes of 18 patients, mean age 66 ± 11 years, were included. Eight eyes (44%) had intraoperative posterior capsule rupture. Before treatment with the Nd:YAG laser, all patients had subjective visual complaints, with 6 patients reporting counting fingers or worse visual acuity. Eleven patients (61%) were successfully treated with 1 session of cortical lysis, while 5 patients underwent 2 and 2 patients underwent 3 or more treatments. Five patients (28%) had elevated intraocular pressure (IOP) within 1 day of treatment, and 1 patient developed cystoid macular edema. All patients had resolution of subjective visual symptoms, and at final follow-up corrected distance acuity was 20/25 or better in 13 patients (72%). The Nd:YAG laser can be used to lyse residual cortex after uncomplicated cataract surgery or cases with intraoperative posterior capsular rupture, and results in an improvement in subjective and corrected distance visual acuity. Elevated IOP is a common complication.

Eye refraction: a comparative study between autorefractometer, aberrometer and subjective test

AbstractPurpose To compare the ocular refractions given by three different techniques and to determine which provides better visual comfort.Methods All subjects underwent a completed optometric examination including clinical history, biomicroscopy of the anterior segment, subjective best corrected visual acuity, autoref/keratometer WAM‐5500 and aberrometer iTrace. Monocular measurements were made under natural accommodation and pupil size. The conditions of the tests were vertex distance 12mm, resolution of the refraction 0.12D, distance 7m and 3 measures each time. Subjects were classified as myopic group (20 eyes) if they presented subjective refraction ≥|‐0.50|D and low‐hyperopic/emmetropic group (22 eyes) if their subjective refraction was &lt;|‐0.50|D. The equipments were calibrated with an artificial eye before the tests were done.Results Subjects chose as the best refractive option the subjective refraction (over 50% in all cases). In hyperopic/emmetropic eyes, subjective refraction showed smaller spheric values (0.22 and 0.18 D comparing to the autorefractor and the aberrometer respectively) and cylinder (0.17 D and 0.21 D, respectively), whereas in the myopic group, the autorefractor gave higher spheric values (0.21 and 0.26D comapring to the aberrometer and the subjective method respectively).Conclusion Most subjects involved in the present study achieved a better visual comfort with subjective refraction. Significant differences among the three techniques were found, although objective methods represent a good approximation to the refraction.

Assessment of visual disability using visual evoked potentials

BackgroundThe purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions.MethodsA retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9–42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19–36 years), 19 optic neuritis patients (19 eyes: ages 9–71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes.ResultsLinear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = −0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = −0.072x + 1.22 (−0.072). This resulted in a prediction reference of visual acuity associated with malingering vs. real disability in a range >5.77 μV. The results could be useful, especially in cases of no obvious pale disc with trauma.ConclusionsVisual acuity quantification using absolute value of amplitude in pattern visual evoked potentials was useful in confirming subjective visual acuity for cutoff values >5.77 μV in disability evaluation to discriminate the malingering from real disability.

Comparison of two methods of extrapolating sweep pattern visual evoked potential acuity

Background Sweep pattern visual evoked potential (SVEP) is an objective method of visual test.There is a clear correlation between SVEP acuity and subjective vision,but they are not identical.Recent studies showed that new regression method can improve the accuracy of SVEP acuity. Objective This trial was to investigate and compare the outcome between amplitude-spatial frequency (A-SP) regression method and amplitudelogVA (A-logVA) regression method in extrapolating the SVEP acuity.Methods SVEP was recorded in 113 eyes of 64 subjects using GT-2000 ( Guo Te,China) with the gratings of 10 different spatial frequency from 0.99 to 12.89 cpd as stimulus.The 1 13 eyes included cataract,glaucoma,corneal disease,optical neuropathy,retinal disease,ocular trauma,refractive error and normal eyes.The correlation were analyzed of SVEP acuity,decimal visual acuity and LogMAR visual acuity.The response were averaged and DFT on the monitor display.SVEP acuity was calculated by extrapolating 0 response amplitude.Results The correlation indices of decimal visual acuity curves obtained by the A-logVA function was 0.663,and that obtained by the A-SP function was 0.705.The positive correlation was seen between subjective decimal visual acuity and A-logVA decimal visual acuity (r =0.540,P＜ 0.01 ) and between subjective decimal acuity and decimal acuity calculated by the A-SP regression method (r=0.620,P＜0.01 ).SVEP decimal acuity calculated by the A-SP function regression method was significantly different from the that calculated by the A-logVA function regression method (Z =-8.688,P＜0.01 ).And the correlation indices of LogMAR visual acuity curves obtained by the A-logVA function was 0.733 and that obtained by the A-SP function was 0.715.The positive correlation was found between the subjective LogMAR acuity and that calculated by the A-SP regression method (r=0.700,P＜ 0.01 ) and between the subjective LogMAR acuity and LogMAR acuity calculated by the A-logVA regression method (r=0.710,P＜0.01 ).SVEP LogMAR acuity from A-SP function regression method was significantly different from the LogMAR acuity from A-logVA function regression method (Z=-8.748,P＜0.01 ).No significant differences of VA LogMAR were found in gender,eyes,type of disease and age(x2 =2.171,P=0.338;x2 =0.976,P=0.614;x2 =6.032,P=0.420;x2 =14.720,P=0.257 ).Conclusions SVEP can obtain the visual outcome in human.The amplitude-logVA function regression method is more accurate in extrapolating SVEP acuity. Key words: Sweep visual evoked potential; Decimal visual acuity; LogMAR acuity

Effects of single mode's high-order aberrations on visual acuity corrected using adaptive optics technique

To analyze the effects of single mode's high-order aberration on visual acuity in real time dynamically corrected using adaptive optics technique. Control study. In a dark room, twelve young healthy volunteers were administrated with 5 g/L phenylephrine to fully dilate the right eye's pupil to a diameter over 6 mm. The subjects' myopia and astigmatism were fully corrected using optical lenses. Coma, trefoil, spherical aberration and other forth-order aberrations except for spherical aberration were corrected using adaptive optics, and 100% contrast visual acuity was simultaneously measured. All single mode's high-order aberrations were fully corrected, whereas other aberrations remained unchanged. Mean visual acuity of subjects was improved by 0.021 LogMAR, 0.017 LogMAR, 0.022 LogMAR and 0.025 LogMAR after correction of coma, trefoil, spherical aberration and other forth-order aberrations except for spherical aberration, respectively. Ratio of change in visual acuity was (-0.40 ± 1.22) LogMAR/µm, (-0.20 ± 0.61) LogMAR/µm, (-0.80 ± 1.44) LogMAR/µm and (-0.30 ± 0.57) LogMAR/µm, respectively. There was a linear correlation between visual acuity after correction of single mode's different high-order aberrations and RMS of residual aberrations (R(2) = 0.13, P < 0.01). Among high-order aberrations in normal human eye, spherical aberration generates a most impact on visual acuity, followed by coma, other forth-order aberrations except for spherical aberration and trefoil. A linear correlation was found between change in visual acuity and RMS of residual aberrations.

Subjective visual acuity with simulated defocus

Artificial degradation of vision by inducing dioptric blur is frequently used for evaluating diagnostic equipment. However, the use of lenses is prone to errors as it is adversely affected by eyelid squinting, pupil size, and imprecise lens position. The alternative is a degradation of the stimuli themselves based on a Fourier-optical mathematical model. With this, however, perceptual effects such as 'simultaneous blur' induced by the surround may affect acuity. We tested whether both methods, lens induced defocus and mathematical stimulus degradation, yield concordant results. We compared both methods in normal subjects, measuring Landolt C acuity at five different levels of defocus from 0 to 8 dioptres. The pupil size was determined individually, chromatic aberrations were avoided by using a monochromatic approach, and a correction for spectacle magnification was included. Otherwise, the experimental design was kept deliberately simple to remain comparable to typical applications. With the major sources of error associated with the use of lenses being accounted for, both methods yield similar mean results with differences in acuity ranging from <0.001 to 0.054 logMAR (0.2-13%). Using mathematically simulated defocus is a viable option if both reasonable accuracy and ease of use are required. The fact that the application of the mathematical model only blurs the stimulus itself, but not the surrounding environment, does not appear to be detrimental to the method.

Contributions of Optical and Non-Optical Blur to Variation in Visual Acuity

To determine the relative contributions of optical and non-optical sources of intrinsic blur to variations in visual acuity (VA) among normally sighted subjects. Best-corrected VA of 16 normally sighted subjects was measured using briefly presented (59 ms) tumbling E optotypes that were either unblurred or blurred through convolution with Gaussian functions of different widths. A standard model of intrinsic blur was used to estimate each subject's equivalent intrinsic blur (σint) and VA for the unblurred tumbling E (MAR0). For 14 subjects, a radially averaged optical point spread function due to higher-order aberrations was derived by Shack-Hartmann aberrometry and fit with a Gaussian function. The standard deviation of the best-fit Gaussian function defined optical blur (σopt). An index of non-optical blur (η) was defined as 1 - σopt/σint. A control experiment was conducted on five subjects to evaluate the effect of stimulus duration on MAR0 and σint. RESULTS.: The logarithm of the minimum angle of resolution (logMAR₀) for the briefly presented E was correlated significantly with log σint (r = 0.95, p < 0.01), consistent with previous work. However, logMAR₀ was not correlated significantly with log σopt (r = 0.46, p = 0.11). For subjects with logMAR₀ equivalent to ~20/20 or better, logMAR₀ was independent of log η, whereas for subjects with larger logMAR₀ values, logMAR₀ was proportional to log η. The control experiment showed a statistically significant effect of stimulus duration on logMAR₀ (p < 0.01) but a non-significant effect on σint (p = 0.13). The relative contributions of optical and non-optical blur to VA varied among the subjects and were related to the subject's VA. Evaluating optical and non-optical blur may be useful for predicting changes in VA following procedures that improve the optics of the eye in patients with both optical and non-optical sources of VA loss.

Improvement of Visual Acuity as An Aftereffect of Blur Adaptation through a Defocusing Lens

Our previous study has shown that blur adaptation through a foggy filter temporarily improved visual acuity (VA). Here we report the influence on VA from the adaptation to blurred images by a defocusing lens. In the experiment, a subject adapted to the blurred visual field by observing motion pictures through a trial lens either of 2.5D, 3.0D, 4.0D, or 5.0D. The visual acuity was measured in the periods of pre- and post-adaptation by a quick and simplified staircase method with Landolt C. The moment the lens was removed, subject's VA was obviously higher than the original VA and then gradually returned to the original level in a few minutes. However the degree of transient improvement in VA was not necessarily larger with longer period of adaptation. The enhancement in VA demonstrated here is presumably caused by blur adaptation and its aftereffect. The usual VA might not be the optimum performance of the hardware of an eye, or rather, be suppressed by the visual system in the level of the cortex.

Wavefront-optimized Surface Ablation With the Allegretto Wave Eye-Q Excimer Laser Platform: 12-month Visual and Refractive Results

To evaluate the wavefront-optimized algorithm of the Allegretto Wave Eye-Q (Wavelight AG) 400-Hz excimer laser platform. Three hundred three eyes of 303 patients treated with advanced surface ablation were evaluated prospectively. Topical mitomycin C (MMC) was used when ablation was ≥80 μm. Efficacy, safety, and predictability at 12 months were quantified with subjective refraction, visual acuity (logMAR), and slit-lamp examination. Mean postoperative uncorrected distance visual acuity (UDVA) was 20/20.5 (0.01±0.05 logMAR). Postoperative UDVA was equal or better than preoperative corrected distance visual acuity (CDVA) in 94.7% of eyes. Efficacy index was 1.05. Corrected distance visual acuity was maintained (93.7%) or improved (5.9%) in 99.6% of treated eyes. No patient lost ≥2 lines. Safety index was 1.05. Haze at 12 months was grade ≤0.5 in 98% of treated eyes and grade ≤1 in 100% of treated eyes. Mean postoperative manifest refraction spherical equivalent (MRSE) was -0.03±0.15 diopters (D). Postoperative MRSE was within ±0.50 D in 99% of eyes. Overcorrection was documented in 0.66% and undercorrection in 0.33% of eyes. The wavefront-optimized algorithm of the Allegretto Wave Eye-Q excimer laser platform showed good efficacy, safety, and predictability in advanced surface ablation, with or without MMC intraoperative use.

Dynamic Visual Acuity During Walking After Long-Duration Spaceflight

Astronauts experience alterations in gaze control as a result of adaptive changes in eye-head coordination produced by microgravity exposure. This may lead to potential changes in postflight visual acuity during head and body motion. We gathered dynamic visual acuity (DVA) data from 14 astronauts and cosmonauts after long-duration (approximately 6 mo) stays in space. Walking was used to induce self-motion and visual acuity was determined by sequentially presenting Landolt ring optotypes on a computer display placed 4 m in front of subjects. Acuity assessments were made while seated (static condition) and walking (dynamic condition) at 6.4 km x h(-1) on a motorized treadmill. In each condition, a psychophysical threshold detection algorithm minimized the required number of optotype presentations by maximizing the amount displayed around the subject's acuity threshold. The difference between static and dynamic acuity measures provided a metric of change in the subjects' ability to maintain gaze fixation on the visual target while walking. A decrement in postflight visual acuity during walking was found. A mean dynamic acuity decrement of approximately 0.75 eye-chart lines was observed 1 d after returning from space. The population mean showed a consistent improvement in DVA performance during the first postflight week. The recovery curves for individual subjects did not necessarily follow a pattern of continuous improvement with each passing day. When adjusted for previous long-duration flight experience, the population mean showed an unexpected DVA reduction in the re-adaptation curve that is similar to recovery patterns observed in prism adaptation studies.

Long-term visual acuity and initial postoperative refractive error in pediatric pseudophakia

Objective: To examine the long-term best-corrected visual acuity (BCVA) in children who, during the amblyogenic period, underwent cataract extraction with intraocular lens (IOL) implantation and to see if initial postoperative refractive error following cataract extraction correlates with long-term BCVA. Design: Retrospective chart review. Participants: Thirty-six eyes of 26 patients were included in the study. At least 2 years of follow-up, an age < 8.5 years at time of IOL implantation, an ability to participate in subjective visual acuity measurement, and an absence of congenital glaucoma and significant trauma were required for inclusion in the study. Methods: Retrospective review of pseudophakic patients' charts at a tertiary care centre, with attention to initial and long-term pseudophakic refractive error, long-term BcVa, total myopic shift, length of follow-up, age at IOL implantation, and unilateral or bilateral cataract extraction with IOL implantation. Results: Initial pseudophakic spherical equivalent (SE) showed asignificant nonlinear relationship with most recent BCVA in unilateral cases and no relationship in bilateral cases (interaction p = 0.001). Unilateral cases with initial pseudophakic SE between +1.75 D and +5.00 D showed better long-term BCVA than those with values below +1.75 D or above +5.00 D; this was irrespective of the refractive error of their fellow eye. Conclusions: In patients receiving lens implants in the first 8 years of life, we recommend aiming for low early postoperative hyperopia, taking into consideration each patient's situation and age.

A Comparison between Subjective Refraction and Aberrometry-Derived Refraction in Keratoconus Patients and Control Subjects

Purpose: This study compares the differences in the magnitude of the subjective refraction and three aberrometry-derived refractions along with visual acuity achieved with these refractions in a group of keratoconic patients and age-matched normal subjects.Materials and Methods: Subjective refraction and Hartmann-Shack aberrometry was performed on six keratoconus patients and 12 normal subjects. In addition, the logMAR visual acuity achieved using the subjective and aberrometry auto-refraction data were measured in the six keratoconic subjects.Results: The subjective and aberrometry-derived spherical equivalent refraction data were significantly different in the keratoconus group (p = 0.015) but not in the normal group (p = 0.10). In the keratoconic patients, subjective refraction data gave better logMAR acuity than the aberrometry-derived auto-refraction data. The magnitudes of vertical coma and higher-order RMS (root mean square) error showed significant correlations with the subjective refraction logMAR visual acuities. Significant correlations were found between the magnitudes of manifest vertical coma and higher-order RMS error and the difference in the M (the mean equivalent sphere) power vector terms between the subjective and aberrometry-derived auto-refraction data in the keratoconic group.Conclusions: The subjective and aberrometry-derived spherical equivalent refraction data were significantly different in the keratoconus group. The larger the magnitude of the higher-order aberrations in keratoconic eyes, the poorer the subjective refraction logMAR acuity and the larger the difference between the subjective and aberrometry-derived M power vector terms. Further investigation into deriving objective refraction data from aberrometry measurements is warranted in keratoconus.

The exact estimation of visual acuity by VEP technology: A report of 726 cases of eye injury

This study explored the accuracy of using visual evoked potentials (VEP) technology for visual acuity estimation. The enrolled 726 patients with post-traumatic unilateral decrease in visual acuity included the injured eyes served as the experimental group, and the healthy eyes as the control group. The least signal visual angle (LSVA), and amplitude and latency of P(100) were chosen as test indexes. The results under different experimental conditions were recorded by PRVEP technology. All data collected were processed and analyzed by SPSS software. The results showed that the coincidence between subjective and VEP visual acuity was 96.7% in control group, but there was very significant difference in experimental group. It was concluded that with the regression formulation for the amplitude of P(100) and vision under LSVA, visual acuity can be estimated more accurately and impartially.

Clinical Evaluation of Dynamic Visual Acuity in Subjects With Unilateral Vestibular Hypofunction

Clinical Evaluation of Dynamic Visual Acuity in Subjects With Unilateral Vestibular Hypofunction

A two-week clinical evaluation of the safety of Systane&amp;reg; Ultra in contact lens-wearing patients

To evaluate the safety of Systane((R)) Ultra Lubricant Eye Drops (test solution) in contact lens wearers. A currently marketed contact lens rewetting drop was the control solution. This investigator- and patient-masked, single-site, randomized, and prospective study involved 45 successful contact lens wearers. Eligible subjects' baseline biomicroscopy findings, visual acuity, and corneal staining score were recorded. Subjects received either the test or control solution with masked labeling. Subjects were instructed to instill their assigned solution in both eyes: 15 minutes prior to lens insertion, at least one drop during lens wear and another drop immediately following lens removal. After 14 days, biomicroscopy results, visual acuity, and corneal staining score were recorded. No adverse events were documented for either the test or the control solution. For subjects using Systane((R)) Ultra, no statistically significant change was detected in visual acuity (= 0.7667) or corneal staining score (P = 1.000). For subjects using the control solution, the change in visual acuity (P = 0.0011, mean difference = 1.70 +/- 3.22 standard deviation) was not clinically relevant and there was no significant change in corneal staining score (P = 0.5413). This clinical study provided evidence of safety and compatibility of Systane Ultra Lubricant Eye Drops in contact lens wearers.