Ocular Straylight: A Determinant of Quality of Life in the Elderly?

Subjective Straylight Index: A Visual Test for Retinal Contrast Assessment as a Function of Veiling Glare

Spatial aspects of visual performance are usually evaluated through visual acuity charts and contrast sensitivity (CS) tests. CS tests are generated by vanishing the contrast level of the visual charts. However, the quality of retinal images can be affected by both ocular aberrations and scattering effects and none of those factors are incorporated as parameters in visual tests in clinical practice. We propose a new computational methodology to generate visual acuity charts affected by ocular scattering effects. The generation of glare effects on the visual tests is reached by combining an ocular straylight meter methodology with the Commission Internationale de l'Eclairage's (CIE) general disability glare formula. A new function for retinal contrast assessment is proposed, the subjective straylight function (SSF), which provides the maximum tolerance to the perception of straylight in an observed visual acuity test. Once the SSF is obtained, the subjective straylight index (SSI) is defined as the area under the SSF curve. Results report the normal values of the SSI in a population of 30 young healthy subjects (19 ± 1 years old), a peak centered at SSI = 0.46 of a normal distribution was found. SSI was also evaluated as a function of both spatial and temporal aspects of vision. Ocular wavefront measures revealed a statistical correlation of the SSI with defocus and trefoil terms. In addition, the time recovery (TR) after induced total disability glare and the SSI were related; in particular, the higher the RT, the greater the SSI value for high- and mid-contrast levels of the visual test. No relationships were found for low contrast visual targets. To conclude, a new computational method for retinal contrast assessment as a function of ocular straylight was proposed as a complementary subjective test for visual function performance.

Validation of a method to assess night myopia in a clinical setting

A study was conducted with 115 subjects who regularly drove at night to validate a refraction protocol for detecting refractive visual changes from daytime to nighttime conditions. Objective and subjective refractions were performed in both photopic and mesopic conditions, with a dark adaptation period before the mesopic subjective refraction. The results showed that in mesopic conditions, visual acuity decreased by 0.2 logMAR units on average (p < 0.01), and there was a myopic refractive shift of - 0.36 ± 0.20 D (p < 0.01). Most subjects (92.2%) exhibited a myopic refractive shift of at least 0.12 D. Compensation of refractive shift improved mesopic visual acuity by 0.06 logMAR on average (p < 0.01) and higher refractive shifts showed higher improvement. Night Rx was preferred by 82.1% of subjects with myopic refractive shift. Gender and age did not significantly affect the refractive shift, although myopes showed a higher shift compared to emmetropes (p < 0.01). The refractive shift remained stable over time when the time slot of the day did not change (p < 0.01). Night Rx protocol proved to be a robust and accurate method for identifying drivers with refractive changes when transitioning from photopic to mesopic conditions. The high prevalence and inter-individual variability of Rx shift highlight the need of customized refraction.

A narrative review of intraocular lens opacifications: update 2020

The opacifications of intraocular lenses (IOLs) can significantly impact patients visual quality. Despite the identification of specific risk factors, manufacturing changes, opacifications are not eliminated. Likewise, more attention in recent studies was paid to possible new risk factors, however one of the most important purposes of the studies remains opacifications effect on visual performance, which could be disturbed in different aspects. The aim of this review is to discuss the main risk factors of IOLs opacification in particular IOL types, and its impact on vision quality. Different risk factors were discussed in the study, including the material of IOLs, the impact of the breakdown of blood-aqueous barrier (BAB), and certain surgeries that can be associated with opacification formation. Glistenings occur more often in a hydrophobic material, however, the changes in water content of the IOLs can significantly reduce the formation of glistenings. The studies showed a significant effect of intraocular injection of exogenous air or gas during Descemet-stripping endothelial keratoplasty, Descemet-stripping automated endothelial keratoplasty, Descemet membrane endothelial keratoplasty, and pars plana vitrectomy on calcification formation. It raises a concern, as the incidence of these surgeries is increasing. Visual acuity decreases significantly after the calcification in IOLs occurs, and it usually causes IOLs exchange. However, disability glare seems to be more affected in patients with IOLs, which were affected by glistenings than visual acuity. Disability glare is associated with increased levels of straylight, which was widely evaluated in recent studies and it was reported to be a susceptible measurement to detect the presence of IOLs pathology. For future researches, it should be noticed that disability glare and straylight are more appropriate in evaluating IOLs opacification effect on visual quality than visual acuity. While reviewing the main risk factors of IOLs opacifications particular attention must be paid on calcification occurrence in hydrophilic acrylic IOLs after surgeries with intraocular injection of exogenous air or gas.

Evaluation of retinal light scattering, visual acuity, refraction and subjective satisfaction in patients after Acrysof IQ PanOptix intraocular lens implantation

AIM

To evaluate the retinal light scattering, visual acuity, refraction and subjective satisfaction in patients after implantation of Acrysof IQ PanOptix intraocular lens.

METHODS

Our group included 32 eyes of 21 patients who underwent cataract surgery or refractive lensectomy with Acrysof IQ PanOptix multifocal intraocular lens implantation at the Ophthalmology Clinic of Faculty Hospital Hradec Králové during the time from September 2015 to December 2017. The observed parameters were visual acuity, subjective refraction, retinal light scattering and patient subjective satisfaction. Preoperative refractive values and visual acuity values were compared with results obtained on day 1, 1 month and at an average of 27 months postoperatively. Subjective satisfaction and degree of light scattering on the retina were evaluated at the end of the follow-up period.

RESULTS

Preoperative, uncorrected distant visual acuity improved from an average of 0,51 ± 0,29 (expressed in decimal values) to 0,94 ± 0,10 at the end of the follow-up period. Preoperative best-corrected distance visual acuity improved from an average of 0,95 ± 0,19 to 1,00 ± 0,09 at the end of the follow-up period. The mean value of preoperative uncorrected near visual acuity was 8,29 ± 4,93 of Jaeger charts, the mean value of uncorrected near visual acuity at the end of the follow-up period was 1,00 ± 0 of Jaeger charts. Subjective satisfaction was assessed using a standardized VF-14 questionnaire at least 1 year after surgery (mean follow-up of 27 months). Retinal light scattering was examined using an Oculus C-Quant instrument. The retinal light scattering value in our sample was 1,12 ± 0,19. In only 6 eyes of 4 patients, the resulting value was outside the physiological range used for eyes with lens crystallina Conclusion: The value of light scattering on the retina is a factor affecting the degree of sensitivity to glare after implantation of multifocal intraocular lenses. In our group, we observed a deviation from the physiological range of retinal light scattering in only 6 eyes of 4 patients, but this did not lead to a deterioration in subjective postoperative satisfaction.