Low-contrast Distance Visual Acuity Research Articles

Randomised controlled trial of HOYA one-day multifocal contact lenses: The HOMCL trial

Trial designDouble-masked crossover RCT (Research Registry: #8136) comparison of a new HOYA one-day disposable multifocal contact lens (HOMCL) with Alcon DAILIES TOTAL1® Multifocal (ADT1). MethodsSixty presbyopic participants from three countries attended for baseline measurements and fitting of both lens types and then for a fortnight completed daily diaries of symptoms with habitual optical correction, and VF-14 questionnaire. Participants collected either HOMCL or ADT1, when the vision was measured again, and they wore this product for a fortnight, completing daily diaries and VF-14. Participants then collected the other type and had vision and symptoms recorded in the same way. ResultsThere were no serious adverse events. Primary outcomes were no significant differences between the lens types in willingness to purchase nor stated preference; no significant differences in the daily symptom ratings of comfort; statistically significant findings with the daily symptom ratings and VF-14 of better near vision with HOMCL and better distance vision with ADT1. Secondary outcomes were better high contrast distance visual acuity with ADT1 (<1 line), better low contrast distance visual acuity with ADT1; faster Wilkins rate of reading test with HOMCL; no significant differences in near visual acuity, wearing time, or number of lenses required during fitting process. Exploratory analyses were better handling scores with ADT1; and some, but not all of the dry eye data indicating better acceptance of HOMCL by patients with relatively dry eyes. For all measures, there were some participants who preferred/performed better with each lens type. ConclusionsThe differences between the performance of the two products were small. There was a trend in some clinical measurements and the daily diary data and VF-14 questionnaire, for HOMCL to outperform ADT1 for near vision and vice versa for distance vision.

Multifocal versus modified monovision corrections: A non-dispensing comparison of visual assessment in presbyopic neophytes.

To compare the visual performance of two simultaneous-vision soft multifocal contact lenses and to compare multifocal contact lens and its modified monovision counterpart in presbyopic neophytes. A double-masked, prospective, comparative study was conducted on 19 participants fitted with soft PureVision2 multifocal (PVMF) and clariti multifocal (CMF) lenses in random order. High- and low-contrast distance visual acuity, near visual acuity, stereopsis, contrast sensitivity, and glare acuity were measured. The measurements were conducted using multifocal and modified monovision design with one brand and then repeated with another brand of lens. High-contrast distance visual acuity showed a significant difference between CMF (0.00 [-0.10-0.04]) and PureVision2 modified monovision (PVMMV; -0.10 [-0.14-0.00]) correction (P = 0.003) and also between CMF and clariti modified monovision (CMMV; -0.10 [-0.20-0.00]) correction (P = 0.002). Both modified monovision lenses outperformed CMF. The current study did not show any statistically significant difference between contact lens corrections for low-contrast visual acuity, near visual acuity, and contrast sensitivity (P > 0.01). Stereopsis at near distance was significantly lower with both modified monovision (PVMMV: 70 [50-85]; P = 0.007, CMMV: 70 [70-100]; P = 0.006) and with CMF (50 [40-70]; P = 0.005) when compared to spectacles (50 [30-70]). Glare acuity was significantly lower with multifocal (PVMF: 0.46 [0.40-0.50]; P = 0.001, CMF: 0.40 [0.40-0.46]; P = 0.007) compared with spectacles (0.40 [0.30-0.40]), but no significant difference was noted between the multifocal contact lenses (P = 0.033). Modified monovision provided superior high-contrast vision compared to multifocal correction. Multifocal corrections performed better for stereopsis when compared to modified monovision. In parameters like low-contrast visual acuity, near acuity, and contrast sensitivity, both the corrections performed similarly. Both multifocal designs showed comparable visual performances.

Correction of Ocular Aberrations with Prismatic Rigid Gas-permeable Contact Lenses in Keratoconic Eyes.

A base-down prism was incorporated on the anterior surface of rigid gas-permeable (RGP) contact lenses to explore potential effects on the residual ocular aberrations after contact lens fitting in keratoconic eyes. This study aimed to evaluate the correction of ocular aberrations with corneal prismatic RGP contact lenses in keratoconic eyes and their impact on visual function. A cross-sectional and randomized study was performed. Seventeen eyes of 17 keratoconus patients (34.6 ± 11.1 years) were evaluated. Two designs (standard and prismatic) of a corneal RGP contact lens (KAKC; Conoptica, Barcelona, Spain) were fitted to the same eye of each patient in a random order: a standard RGP contact lens as control and a prismatic RGP contact lens with a base-down prism of 1.6 prism diopters. Ocular aberrations were measured for a pupil diameter of 3 mm with and without both contact lenses, whereas high-contrast distance visual acuity, low-contrast distance visual acuity, and contrast sensitivity were measured under photopic and mesopic conditions. Both contact lenses improved oblique primary astigmatism, defocus, vertical coma, coma-like, and root-mean-square higher-order aberrations compared with the unaided eyes (P < .05). Furthermore, the prismatic RGP contact lenses offered lower values of vertical coma and root-mean-square higher-order aberrations than the standard RGP contact lenses (P < .05). Both designs (standard and prismatic) produced a positive vertical coma of lower magnitude than the negative vertical coma of the unaided eyes. On the other hand, the improvement achieved in all visual function variables was the same for both contact lens designs (P ≥ .05). The prismatic RGP contact lenses corrected higher levels of higher-order aberrations compared with the standard RGP contact lenses. However, both contact lens designs with the same refractive power were equally efficient at improving visual function.

Subjective and objective clinical outcomes of a new trifocal toric intraocular lens and effect of femtosecond laser cataract surgery.

To evaluate the clinical outcomes and quality of life following implantation of PanOptix toric intraocular lens (IOL) and to compare the outcomes following femtosecond laser assisted cataract surgery (FLACS) and standard cataract surgery (SCS). This comparative retrospective study included 79 eyes of 55 patients underwent cataract or refractive lens exchange surgery between April 2017 and January 2020 in Bayindir Hospital and Kaskaloglu Eye Hospital. Corneal (CA) and refractive astigmatism (RA), uncorrected visual acuities for distant, intermediate, and near (UDVA, UIVA, and UNVA), low contrast distance visual acuity, rotational stability, defocus curves, photopic and mesopic contrast sensitivity (CS), visual function-14 (VF-14) test, presence of dysphotopsia, and need for spectacles were evaluated at postoperative third month. Outcomes were compared between FLACS and SCS group. The mean UDVA, UIVA, and UNVA were 0.05 ± 0.07, 0.08 ± 0.08, and 0.06 ± 0.07 logMAR, respectively. All patients achieved ⩾0.3 logMAR uncorrected visual acuity for all distances. UDVA was found significantly better in FLACS group (p = 0.03). All eyes had ⩽1 D of subjective postoperative RA. Defocus curve had two peaks at 0 and -1.50 D. Spectacle independence was achieved in 88.7% of patients. Photopic and mesopic CS was within normal range in all patients. The mean VF-14 score was 98 ± 2. The mean IOL axis rotation was 2.1° ± 2.3°. Only one patient reported seeing disturbing halos. This trifocal toric IOL effectively reduced refractive astigmatism and provided excellent visual outcomes with high spectacle independence, patients' satisfaction, and good rotational stability. FLACS might have an impact on optimal postoperative results.

Effects of Light Scatter and Blur on Low-Contrast Vision and Disk Halo Size.

To investigate the individual effects of forward light scatter (FLS) and refractive blur on low-contrast vision and the size of the disk halo produced in response to an external glare source. Monocular disk halo radius, high- and low-contrast distance visual acuity (HCVA, LCVA), and contrast sensitivity (CS) were determined in 25 eyes of 25 healthy subjects under normal, FLS, and blur conditions. FLS was induced using the filter Black ProMist 2 to simulate an early cataract. Blur was induced using a +1.00 diopter lens to simulate an uncorrected refractive error. Similar significant mean increases in halo radius were observed for the FLS (0.32 ± 0.10 log arc min; P < .0001) and refractive blur (0.40 ± 0.18 log arc min; P < .0001). Under induced blur, 3 lines of HCVA (0.32 ± 0.15 logMAR; P < .0001) and 4 lines of LCVA (0.39 ± 0.16 logMAR; P < .0001) were lost. FLS had a minimal (but significant) effect on HCVA, but worsened mean LCVA by more than 1 line (0.13 ± 0.10 logMAR; P < .0001). Similar significant mean CS reductions of 0.17 ± 0.12 (P < .0001) and 0.14 ± 0.12 log units (P < .0001) were produced in response to FLS and refractive blur, respectively (approximately 1 triplet). Forward light scatter and refractive blur contributed to an increased size of the disk halo produced by a glare source in similar proportion. Although defocus blur has a substantial effect on LCVA, a loss of more than 1 line of LCVA after best refractive correction would be indicative of FLS.

Impact of Spherical Aberration Terms on Multifocal Contact Lens Performance.

To investigate the impact of the primary (PSA) and secondary (SSA) spherical aberration terms on visual performance (VP) in presbyopes, as measured using multifocal (MFCL) soft contact lenses on eye. Seventeen presbyopes (age: 55.1 ± 6.9 years) wore seven commercial lenses (four center-near (MFCL N), one center-distance (MFCL D), one bifocal, and one single vision control). Unaided and with each lens on eye, the PSA and SSA terms were obtained with an aberrometer, the BHVI-EyeMapper (low illumination, natural and 4 mm pupil diameter). High- and low-contrast distance visual acuity, contrast sensitivity, high-contrast visual acuities at near, and range of clear vision were measured. In addition, subjective VP variables included clarity of vision at distance and near, ghosting, and overall vision satisfaction. Pearson's correlation was used to determine the association between the PSA and SSA terms and the VP variables. PSA (natural pupil) was more negative (P < .05) with the MFCL N (mean PSA = -0.053 ± 0.080 μm) and bifocal (PSA = +0.005 ± 0.067 μm) lenses and more positive with the MFCL D lens (PSA = +0.208 ± 0.160 μm) than the control (+0.067 ± 0.072 μm). SSA (natural pupil) was significantly more positive for the MFCL N lenses (mean SSA = +0.025 ± 0.029 μm) compared to the control (SSA = -0.001 ± 0.017 μm). PSA and SSA terms were significantly (P < .05) correlated with 78% and 56% of VP variables, respectively, but the correlation coefficients were weak, ranging between |0.210| and |0.334|. Although distance variables showed improved VP with more positive PSA or negative SSA, most near variables showed improved VP with more negative PSA. Range of clear focus was greater for more negative PSA terms. The amount and direction of PSA and SSA terms, as measured with different MFCLs on eye, can affect VP at different distances. Results of this study may provide useful information when designing new or optimize existing MFCLs for improved VP at specific distances.

Effect of Induced Accommodation Relaxation Methods on Visual Function in Young Adults

Purpose: To evaluated the effect of induced accommodation relaxation methods on visual function in young adults with monovision, modified monovision and multifocal contact lenses of low add power. Materials and Methods: Twenty two young subjects (23.36 ± 2.57 years) were fitted with single vision contact lenses, monovision, modified monovision and multifocal contact lenses with masking method. After wearing the contact lenses for a week for adaptation, binocular contrast visual acuity (VA) at distance and near, stereoacuity, ghost image, legibility, thread a needle and subjective visual performance with questionnaires were evaluated with each of these modalities. All the assessments of visual function were made after 1 hour watching visual display at computer for induced accommodation. Results: There was no difference in binocular 100% distance contrast visual acuity, 100% and 10% near contrast visual acuity between these modalities and single vision as control, however, 10% binocular distance contrast visual acuity was lowest with monovision(p<0.05). Stereoacuity was lowest with monovision compared with other modalities(p<0.05), and there were no significant differences between other modalities. Both of accuracy and speed of legibility worst with monovision compared with other modalities(p<0.05) and there were no significant differences between other modalities. The distance and near visual satisfaction, stereoacuity and adaptation measured with questionnaires, there were no differences between modified monovision, multifocal contact lenses and single vision contact lens, however, those with monovision showed worst satisfaction. Conclusions: There were no differences in visual function in young subjects fitted with low addition of modified monovision, multifocal contact lenses vs single vision contact lenses, however, with monovision contact lenses, low contrast distance visual acuity, steroacuity, legibility and visual satisfaction were decreased.

Low toric soft contact lens acceptance study.

The aim of the study was to evaluate the objective and subjective visual performance of custom toric contact lenses (TL) and their spherical off-the-shelf counterparts (SL) in subjects with low amounts of astigmatism. Twenty-three habitual soft lens wearers (40 eyes, 25-35 years) manifesting 0.50-1.00DC and ≤±3.00DS were recruited. Air Optix Aqua (Lotrafilcon B) was fit using the spherical equivalent of the manifest refraction. Intelliwave toric in Efrofilcon A (Definitive) was fit using the manifest refraction and keratometric data. Comprehensive visual performance tests were done through manifest refraction in a trial frame; in SL; and in TL. A subjective evaluation of quality of vision was also obtained. ANOVA revealed that, at the morning visit (AM), high contrast logMAR distance visual acuity (HCDVA) was significantly better (p<0.01) in spectacles as compared to SL. A similar trend was noted at the afternoon visit (PM). In addition, at the PM visit, HCDVA was significantly better (p<0.01) for TL as compared to their SL. ANOVA revealed that, at the PM visit, low contrast distance visual acuity (LCDVA) was significantly better (p=0.05) in spectacles as compared to SL. None of these differences were clinically significant. In addition, no statistically significant difference (p>0.05) in subjective vision rating scores was noted between SL and TL. The present investigation found no clinically significant difference in visual performance between spherical and toric soft contact lenses in low astigmats.

Objective and subjective visual performance of multifocal contact lenses: Pilot study

The aim of the present study was to compare the objective and subjective visual performance of three different soft multifocal contact lenses. 10 subjects (habitual soft contact lens wearers) between the ages of 40 and 45 years participated in the study. Three different multifocal silicone hydrogel contact lenses (Acuvue Oasys, Air Optix and Biofinity) were fit within the same visit. All the lenses were fit according to the manufacturers' recommendation using the respective fitting guide. Visual performance tests included low and high contrast distance and near visual acuity, contrast sensitivity, range of clear vision and through-focus curve. Objective visual performance tests included measurement of open field accommodative response at different defocus levels and optical aberrations at different viewing distances. Accommodative response was not significantly different between the three types of multifocal contact lenses at each of the accommodative stimulus levels (p>0.05). Accommodative lag increased for higher stimulus levels for all 3 types of contact lenses. Ocular aberrations were not significantly different between these 3 contact lens designs at each of the different viewing distances (p>0.05). In addition, optical aberrations did not significantly differ between different viewing distances for any of these lenses (p>0.05). ANOVA revealed no significant difference in high and low contrast distance visual acuity as well as near visual acuity and contrast sensitivity function between the 3 multifocal contact lenses and spectacles (p>0.05). There was no statistically significant difference in accommodative response, optical aberrations or visual performance between the 3 multifocal contact lenses in early presbyopes.

Central Retinal Findings in Bothnia Dystrophy Caused by RLBP1 Sequence Variation

To describe the central retinal findings early in the course of Bothnia dystrophy caused by the homozygous missense R234W sequence variation in the RLBP1 gene. In 8 young patients with Bothnia dystrophy (aged 9-34 years), high- and low-contrast distance visual acuity and visual fields were measured with Humphrey central (24-2) threshold testing and Goldmann perimetry. Central retinal thickness was measured with optical coherence tomography. Cross-sectional images were analyzed and a linear scanning protocol was applied to examine retinitis punctata albescence in the posterior pole. Affected visual acuity (4 of 8 cases) and poor low-contrast visual acuity (8 of 8 cases) were found. Significant foveal depression and visual field loss were evident with Humphrey threshold testing at all ages, and paracentral and central scotomata in the second decade of life advanced in adulthood as verified with Goldmann perimetry. Optical coherence tomography showed generalized retinal thinning in the central foveal, foveal (innermost ring diameter [Ø], 1 mm), and inner ring (Ø, 3 mm) areas in all ages, and early retinal thinning was found in the inferior areas of the outer macula (Ø, 6 mm). Foveal and extrafoveal thinning of the retinal layers and outer nuclear layer were found. Homogeneous retinitis punctata albescence changes were visualized in and/or adjacent to the retinal pigment epithelium-choriocapillaris complex with high reflectance. In the RLBP1-Bothnia dystrophy phenotype, a loss of function and thinning of the central macula are found, indicating early damage of the cone photoreceptors in this disease of the visual cycle. Retinitis punctata albescence spots in the posterior pole are situated close to or in the retinal pigment epithelium-choriocapillaris complex.

Increasing negative spherical aberration with soft contact lenses improves high and low contrast visual acuity in young adults

To evaluate the effects of a customised manipulation of spherical aberration (SA) on the high and low contrast visual acuities and contrast sensitivity of young adult myopes. A placebo-controlled double masked trial of customised spherical aberration controlling soft contact lenses was undertaken in myopes aged 15-23. Participants wore customised soft contact lenses with either (i) zero spherical aberration or (ii) negative spherical aberration that resulted in a net SA (eye plus lens) of -0.1 micron. High and low contrast log MAR visual acuities and Pelli Robson contrast sensitivity were assessed in 196 eyes of 98 subjects after a period of 12 months wearing the lenses. Both high and low contrast acuities were significantly better in the group wearing the contact lenses with negative spherical aberration (high contrast log MAR, p = 0.043; low contrast log MAR, p = 0.043) which was not due to differences in residual astigmatism or pupil size between the two groups. Pelli Robson contrast sensitivity was not significantly different in the two groups. Manipulation of spherical aberration, taking account of the participants' baseline level of aberration, can cause statistically significant improvements in high and low contrast distance visual acuity although these improvements are too small in magnitude to be of clinical significance.

Clinical Investigation of Asmofilcon A Silicone Hydrogel Lenses

To investigate the clinical and subjective performance of asmofilcon A, a new third generation silicone hydrogel contact lens during 6-night extended wear (EW) over 6 months. A prospective, randomized, single-masked study was conducted. Sixty experienced daily wear soft contact lens wearers were randomly assigned to wear either asmofilcon A or senofilcon A contact lenses bilaterally for 6 months on an EW basis. Evaluations were conducted at contact lens delivery and after 1 week, 4 weeks, 3 and 6 months of EW. Fifty subjects (83%) successfully completed the study. Two subjects experienced adverse events; one unilateral red eye with asmofilcon A and one asymptomatic infiltrate with senofilcon A. There were no significant differences in high or low contrast distance visual acuity between asmofilcon A and senofilcon A; however, low contrast distance visual acuity decreased significantly over time with both contact lens types (p < 0.05). The two lens types did not vary significantly with respect to any of the objective and subjective measures assessed (p > 0.05). Superior palpebral conjunctival injection showed a statistically significant increase over time with both lens types (p < 0.05). Both lens types were rated highly with respect to overall comfort, with subjects reporting 14 or 15 h of comfortable lens wearing time per day at each of the study visits (p > 0.05). Overall satisfaction ratings were also very high at all visits, with median scores of 95 (86 to 99) for asmofilcon A and 90 (85 to 96) for senofilcon A at 6 months (p > 0.05). Over 6 months of EW, the asmofilcon A contact lens performed in a similar manner to senofilcon A with respect to visual acuity, ocular health, and contact lens performance measures. Longer-term EW studies are required to investigate the changes over time observed with both lens types.

Effect of posterior capsular opacification on visual function in patients with monofocal and multifocal intraocular lenses

To compare the effect of posterior capsular opacification (PCO) on visual function in patients with monofocal and multifocal intraocular lenses (IOLs). Thirty-three consecutive patients with clinically significant PCO, 24 with monofocal, and nine with multifocal IOLs, were recruited. Patients with concurrent cause of visual loss or pupillary distortion were excluded. LogMAR high- and low-contrast (10%) distance visual acuity (VA), logMAR near VA, Pelli-Robson contrast sensitivity (CS), colour confusion index (CCI), and the presenting symptoms were compared between the two groups. There was no significant difference between the proportions of patient with different PCO grade in the two groups. At presentation, high- and low-contrast distance VA were significantly greater in the multifocal group (0.40 vs 0.20; P=0.04 and 0.34 vs 0.98; P=0.006), whereas near VA, CS, and CCI were not significantly different between the two groups. After capsulotomy, the above visual functions were not significantly different between the two groups. Blurred distance and near vision were the most common presenting symptoms (95.8 and 100% in the monofocal group and 88.9 and 66.7% in the multifocal group). A greater proportion of patients in the monofocal group had blurred near vision (100 vs 66.7%) and, whereas the symptoms in the majority of patients in the monofocal group were moderate to severe, they were mild to moderate in the multifocal group. The effect of PCO on visual function in the two groups seems to be comparable, although patients in the multifocal group appear to present with earlier loss of visual function.

Cone-mediated multifocal electroretinogram in early age-related maculopathy and its relationships with subjective macular function tests

Purpose. To investigate the multifocal electroretinogram (mfERG) and subjective function in early age-related maculopathy (ARM). Methods. Seventeen subjects with early ARM with visual acuity (VA) of 6/12 or better and 20 age-matched control subjects were examined. We assessed mfERGs, high and low contrast distance VA, near VA, low luminance VA, contrast sensitivity, saturated and desaturated Panel D-15 and visual fields (mean sensitivity). The mfERG responses were analysed by comparing central-overall (method 1) and superior-inferior (method 2) ratios. Results. The mfERG did not discriminate between the groups whereas colour vision (tritan deficiency), contrast sensitivity, and high contrast and low contrast VA showed significantly reduced responses for the early ARM group compared with the control group (p ≤⃒ 0.01). The mfERG first-order kernel responses correlated significantly with the desaturated D-15 in both methods (r = −0.5, p ≤⃒ 0.05). Fundus grading was not correlated with the mfERG measures. Conclusions. Although the mfERG correlated significantly with the desaturated D-15 in early ARM, suggesting it operates at a sensitive level, it failed to discriminate between the control and ARM groups. In our sample, the subjective function measures were more sensitive than the mfERG measures.