Glare and halo with refractive correction

Influence of Interocular Differences and Alcohol Consumption on Binocular Visual Performance

The purpose of this study was to assess the influence of a moderate breath-alcohol content (BrAC of 0.40 mg/L) on binocular visual performance for different visual functions after inducing different levels of interocular differences with the use of filters. A total of 26 healthy young subjects were enrolled. The participants participated in two sessions: one without alcohol consumption and another after alcohol consumption. In each session and for the different filter conditions (subjects were wearing Bangerter foil of 0.8 and BPM2 fog filter on the dominant eye), monocular and binocular visual function was evaluated by measuring visual acuity, contrast sensitivity, visual discrimination capacity (and successively by calculating their corresponding binocular summations) and stereopsis (near and distance stereoacuity). In addition, interocular differences were calculated for different retinal-image quality and straylight parameters. All monocular and binocular visual functions were analyzed and stereopsis was significantly impaired by alcohol and filters (p < 0.05). Interocular differences for different ocular parameters and binocular summations for visual parameters were negatively affected by filters but not alcohol. Significant correlations (averaging all the experimental conditions analyzed) were found, highlighting: the higher the interocular differences, the lower the binocular summation and the poorer the stereopsis and, therefore, the worse the binocular visual performance.

Changes in Shape Discrimination Sensitivity Under Glare Conditions After Orthokeratology in Myopic Children: A Prospective Study

Purpose

To investigate changes in shape discrimination under mesopic conditions with and without glare after orthokeratology in myopic children.

Methods

This prospective study included 79 eyes of 79 myopic children (ages: 8-16 years). Shape discrimination thresholds (SDTs) were measured using radial frequency patterns, with a radial frequency of 4 cycles/360°, a peak spatial frequency of 3 cycles per degree, a contrast of 20%, and a mean radius of 1.5 degrees. SDT under mesopic conditions with and without glare was measured before orthokeratology and again at 1 week and 1 month after orthokeratology. Changes in the SDTs and their relationships to baseline ocular parameters were analyzed.

Results

SDTs with glare decreased significantly at 1 week (-0.08 ± 0.15 log(arcsec), P < 0.001) and 1 month (-0.09 ± 0.15 log(arcsec), P < 0.001) after orthokeratology. SDTs without glare remained stable (P = 0.81 and P = 1.00, respectively). The difference between SDTs with and without glare also decreased significantly at 1 week (-0.10 ± 0.17 log(arcsec), P < 0.001) and at 1 month (-0.08 ± 0.18 log(arcsec), P = 0.001) after orthokeratology. Based on a multivariate analysis, the greater decrease in SDT with glare after 1 month of orthokeratology was associated with a higher baseline spherical equivalent refraction.

Conclusions

Orthokeratology resulted in improved shape discrimination in myopic children under mesopic conditions but only when measured in the presence of glare.

Minimum pupil in pupillary response to light and myopia affect disk halo size: a cross-sectional study

OBJECTIVES

To evaluate the relationship between pupillary response to light, myopia and disk halo size.

DESIGN

Cross-sectional study.

SETTING

Single refractive surgery centre.

PARTICIPANTS

In this study, 197 right eyes of 197 patients between 20 and 35 years of age were evaluated for disk halo size and pupillary response to light with a vision monitor.

PRIMARY AND SECONDARY OUTCOME MEASURES

Halo radius, age, spherical equivalent (SE), axial length (AL), initial diameter, amplitude of contraction, latency of contraction, duration of contraction, velocity of contraction, latency of dilation, duration of dilation, velocity of dilation, maximum pupil, minimum pupil, average pupil and dark pupil.

RESULTS

Significant associations were found between disk halo size and SE (r=-0.219, P=0.002), AL (r=0.152, P=0.033) and minimum pupil (r=0.149, P=0.037). There were no associations between disk halo size and initial diameter, amplitude of contraction, latency of contraction, duration of contraction, velocity of contraction, latency of dilation, duration of dilation, velocity of dilation, maximum pupil, average pupil, dark pupil and age (P>0.05). A significant difference in disk halo size was detected between the low-moderate and high myopia (SE< -6 D) groups (P=0.002) and between the small and large (minimum pupil≥4 mm) minimum pupil size groups (P=0.014).

CONCLUSIONS

Patients with a high SE and large minimum pupil size (minimum pupil ≥4 mm) suffered more disability glare than those with a low SE and small minimum pupil size.

Normal values for the size of a halo produced by a glare source

PURPOSE

To determine the size of a halo in the visual field induced by bright light in healthy eyes of all ages using the Vision Monitor (MonCv3; Metrovision, Pérenchies, France) and to assess the repeatability of the method.

METHODS

Measurements were made in the right eyes of 147 healthy subjects (mean age: 48.2 ± 16.2 years) who were classified into six age groups. Using the Vision Monitor, optotypes of low luminance were presented at a distance of 2.5 m. The visual angle subtended by the radius of the halo was calculated in minutes of arc (arc min). The repeatability of the method was determined in a subset of 37 subjects older than 50 years by calculating the Bland-Altman coefficient of repeatability.

RESULTS

The mean radius of the halo was 111.6 ± 39.8 arc min. Halo radius started to increase significantly from the age of 50 to 59 years. The relationship between halo radius and age (r = 0.65; P < .0001) was described by fitting a power function to the data. Halo size was independent of gender. The coefficient of repeatability of the method was ±44 arc min.

CONCLUSIONS

Halo size increases with age following a power model. The normal halo size values provided could help clinicians distinguish between normal or abnormal glare problems. The intersession repeatability observed for halo size measurement indicates this method could be useful for assessing visual impairment caused by glare.

Visual outcomes and patient satisfaction after presbyopic lens exchange with a diffractive multifocal intraocular lens

PURPOSE

To investigate the visual outcomes, severity of symptoms, and patient satisfaction after refractive lens exchange (RLE) with a diffractive multifocal intraocular lens (IOL).

METHODS

A nonrandomized, unmasked, retrospective chart review study was performed. Patients who underwent RLE with ZMA00 (Abbott Laboratories) were identified from a hospital database. Eyes with preoperative uncorrected distance visual acuity or corrected distance visual acuity 20/20 or better were included. The study cohort comprised 45 eyes from 29 patients. Monocular uncorrected and distance-corrected visual acuity at distance, 67 cm, and 30 cm were measured 6 months postoperatively. A patient questionnaire assessing visual symptoms (halo, night glare, and starburst) and satisfaction with visual performance was administered.

RESULTS

Six months postoperatively, mean uncorrected visual acuity (logMAR) was -0.10±0.13, 0.43±0.25 at 67 m (intermediate), and 0.18±0.05 at 30 m (near). Mean distance-corrected visual acuity at these distances was -0.02±0.06, 0.40±0.21, and 0.17±0.02, respectively. Twenty-seven patients completed the questionnaire. Patients reported postoperative halos (78%), night glare (26%), and starbursts (48%). All bilateral RLE patients were spectacle-free at all distances, whereas 50% of unilateral RLE patients required spectacles postoperatively. Bilateral RLE patients with habitual spectacle use preoperatively were the most satisfied with their postoperative visual performance.

CONCLUSIONS

Refractive lens exchange with the ZMA00 is an option for presbyopic correction; however, significant glare, halo, and starburst issues are subjectively reported.