Characterizing glare effects associated with diffractive optics in presbyopia-correcting intraocular lenses.

PURPOSE: To objectively quantify glare of intraocular lenses (IOLs) using a diffractive principle to extend the visual range and to identify models with increased susceptibility to inducing glare. SETTING: David J Apple Laboratory, Heidelberg, Germany. DESIGN: Laboratory investigation. METHODS: Glare was assessed by means of a straylight parameter with a standard C-Quant intended for 7 degrees. In addition, 2 C-Quant modifications were used to test lower angles (ie, 2.5 degrees and 3.5 degrees). The following IOL models were assessed: PanOptix, AT Lisa Tri, Synergy, and Triumf, the latter 2 with chromatic aberration correction at distance. Straylight from trifocal IOLs was compared against a monofocal W-60R lens. The C-Quant test was performed through the studied IOLs by using additional optical components attached to their ocular. RESULTS: Straylight (deg 2 sr -1 ) of the control was <1 at all tested angles, with the trifocal models showing comparable straylight at 7 degrees. At 3.5 degrees, Triumf's straylight increased to 15.5 ± 0.6, followed by Synergy (6.2 ± 1.1), PanOptix (4.1 ± 0.3), and AT Lisa Tri (2.0 ± 0.8). The chromatic aberration-correcting models demonstrated correspondingly higher straylight (Synergy: 18.8 ± 1.3; Triumf: 17.3 ± 0.5) at 2.5 degrees compared with PanOptix (4.3 ± 0.4), AT Lisa Tri (2.1 ± 0.1), and monofocal IOLs yielding minimal or no increase. CONCLUSIONS: Trifocal IOLs induced increased straylight, but it was limited to lower angles, which may cause difficulties detecting these effects using a standard clinical approach. The latest IOL designs featuring chromatic aberration correction at far focus seem more susceptible than the established trifocal IOLs to inducing a glare phenomenon.

Changes in straylight after cataract surgery.

PURPOSE: To investigate straylight in the immediate postoperative period after cataract surgery. SETTING: Amphia Hospital, Breda, the Netherlands. DESIGN: Prospective, comparative, single-arm, single-center, single-surgeon study. METHODS: Patients underwent cataract surgery on both eyes. 1 eye was randomly selected for implantation with a Clareon CNA0T0 intraocular lens (IOL); the fellow eye received a Vivinex XY1 IOL. Straylight was measured with the C-Quant straylight meter. RESULTS: 25 patients were included. Preoperatively, 1 day, 1 week, 1 month, and 3 months postoperatively, eyes with a CNA0T0 IOL had straylight levels (mean ± SD) of 1.48 ± 0.23, 1.26 ± 0.20, 1.06 ± 0.19, 1.11 ± 0.25, and 1.09 ± 0.20 log(s), respectively. For eyes with an XY1 IOL, these values were 1.48 ± 0.21, 1.41 ± 0.41, 1.10 ± 0.20, 1.13 ± 0.20, and 1.16 ± 0.20 log(s), respectively. From 1 week postoperatively, straylight values did not change (1 week vs 3 months: P = .40 and P = .14 and 1 month vs 3 months: P = .74 and P = .50 for CNA0T0 and XY1, respectively). The Pearson correlation coefficient for straylight values between the 2 eyes of individual subjects was 0.80 at 3 months. CONCLUSIONS: Straylight levels can be considered stable 1 week after cataract surgery. We believe it is safe to use straylight measurements 1 month postoperatively for clinical trials. Straylight is highly correlated between the 2 eyes of an individual postoperatively.

Diurnal Variation in Straylight in Patients With Fuchs Endothelial Corneal Dystrophy and Controls.

PURPOSE: The goal of this study was to investigate diurnal changes in intraocular straylight in relation to other corneal parameters and subjective complaints in patients with Fuchs endothelial dystrophy and healthy controls. METHODS: This is a prospective study conducted in 2 tertiary care hospitals in Germany and the Netherlands. Patients with Fuchs endothelial dystrophy (n = 71) and healthy controls (n = 34) were included. Patients with Fuchs dystrophy were grouped by the presence of subjective complaints and measured over multiple time points during the day. Measurements included intraocular straylight using the C-Quant and corneal thickness and backscatter using a Scheimpflug camera. A separate group of healthy controls was measured intensively with repeated straylight measurements directly after waking. An exponential decay model was used to model the diurnal change. RESULTS: Healthy controls showed an average straylight baseline of 1.17 log(s) with an increase in straylight after waking of 0.22 log(s). In the repeated measurements subgroup, the increase in morning straylight lasted for 22 minutes. Patients with Fuchs dystrophy showed a morning increase in straylight of 0.21 log(s) present up to 4 hours after waking before reaching an average baseline of 1.30 log(s). Straylight was positively correlated with anterior corneal backscatter, r = 0.21, P = 0.022, and corneal thickness, r = 0.46, P < 0.01. CONCLUSIONS: Healthy eyes experience a diurnal straylight increase similar to patients with Fuchs dystrophy in intensity. However, in Fuchs dystrophy, the resolution of increased straylight is prolonged over multiple hours compared with minutes in healthy eyes. This suggests pathological exacerbation of a physiological diurnal change. This mechanism can play a role in subjective complaints experienced by patients with Fuchs dystrophy.

Light scattering from a diffractive-refractive intraocular lens: a goniometer-based approach for individual zone assessment.

We proposed and tested a method to measure light scattering from the diffractive lens profile in an echelle element featuring 9 zones. Measurements were performed using a goniometer-based setup up to 7.5°. The proportion of scattered light was calculated to derive the loss of light. Material scattering was minimal (∼1 deg2/sr); however, each echelle zone acted as a scattering source. A nearly gradual straylight increase was found with the zone number showing peak intensity between 3° and 3.75°. An estimated 6.2% ± 0.1% was lost due to scattering, which ought to be considered when reporting an IOL's light loss.

Straylight due to intraocular lens opacification in a patient with asteroid hyalosis.

PURPOSE: To report a rare case of intraocular lens (IOL) calcification in the presence of asteroid hyalosis with in-vivo measurements of straylight before and after treatment. OBSERVATIONS: A patient with asteroid hyalosis presented with complaints of disability glare due to calcifications on the posterior surface of the IOL. Straylight, measured with the C-Quant, was 8.2x elevated compared to normal (log(s) 2.08). Dissolution of the posterior face IOL deposits was performed with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, resulting in a significant decrease in straylight (log(s) 1.76), congruent with the patient's subjective improvement. CONCLUSIONS AND IMPORTANCE: To the best of our knowledge, this is the first report describing a patient with an opacified IOL due to asteroid hyalosis with in-vivo measurements of straylight before and after treatment. It illustrates that awareness of glare complaints in patients with an opacified IOL is important, documentation with C-Quant measurements may be helpful in indicating treatment, evaluating the treatment, and following up the patient, and treatment with a Nd:YAG laser may dissolve the opacifications to a clinically satisfactory level.

Quality factor based correction for SD-OCT measurements in cataract patients.

PURPOSE: To correct peripapillary retinal nerve fibre layer (pRNFL) measurements performed with spectral domain optical coherence tomography (SD-OCT) for low image quality factor (QF) in patients with cataract, using measurements before and after cataract surgery. METHODS: SD-OCT (Topcon 3DOCT-2000) volume scans of the optic disc of 13 cataract patients were used. A set of three reflective filters with optical density ranging from 0.11 to 0.54 were used. The correlation was calculated between the change in thickness measurements and the change in image quality factor. Changes before and after cataract surgery were analysed. A correction for scans with a lower QF was calculated using an equation which was formulated based on the relationship between the change in thickness measurements and the change in image quality factor. RESULTS: Thirteen right eyes of thirteen cataract patients were included in this study. pRNFL thickness measurements before and after cataract differed significantly (96 versus 99 micron, p < 0.01). Preoperative linear regression lines showed a different slope than postoperative regression lines. Corrected pRNFL thickness measurements of before cataract surgery differed significantly with pRNFL thickness measurements after cataract surgery. CONCLUSIONS: The presence of cataract influences the QF-pRNFL relationship. The lower the image QF, the higher the pRNFL thickness underestimation. We found a rather curvilinear relationship between QF and pRNFL. Our corrected measurements of the pRNFL thickness in case of lower image QF due to cataract still differed significantly from the pRNFL thickness measurements after cataract surgery.

The Effect of a Spectral Filter on Visual Quality in Patients with an Extended-Depth-Of-Focus Intraocular Lens.

PURPOSE: Wavelength dependence of diffractive intraocular lenses (IOLs) was recognized in vitro but not yet assessed in vivo. By examining pseudophakic patients who had extended-depth-of-focus diffractive implants, this spectral effect on their vision was measured clinically and the lens was tested in vitro. DESIGN: Cross-sectional study with laboratory investigation. METHODS: Twelve pseudophakic patients (23 eyes) with a Symfony lens (Johnson & Johnson Vision) were measured monocularly under red and white light at far, intermediate, and near distances. Corrected distance visual acuity (CDVA), distance-corrected intermediate visual acuity (DCIVA), and distance corrected near visual acuity (DCNVA) were assessed. Contrast sensitivity was examined at several spatial frequencies. The in vitro lens modulation transfer function was measured under different spectral conditions by using an IOL metrology device. RESULTS: CDVA was comparable under red and white light. DCIVA and DCNVA were significantly better under white light by 0.06 and 0.09, respectively. Contrast sensitivity was slightly better with a red filter at far distance but was worse at intermediate distance, although differences were significant only at 1 frequency. Near contrast sensitivity was better under polychromatic than red light, which was significant at 3 frequencies. The in vitro analysis confirmed Symfony's wavelength dependence: performance was improved at far distance but was worse at intermediate and near distances. CONCLUSIONS: Symfony's spectral dependence was observed to affect visual acuity and contrast sensitivity. Although the red filter did not improve distance vision, it caused visual deterioration at near distance. One should take this effect into account when optimizing the reading performance of patients with diffractive IOLs.

Assessment of straylight and the modulation transfer function of intraocular lenses with centrally localized opacification associated with the intraocular injection of gas.

PURPOSE: To assess the optical quality of intraocular lenses (IOLs) explanted because of opacification after the intraocular injection of gas. SETTING: David J. Apple Laboratory, Heidelberg, Germany. DESIGN: Experimental study. METHODS: Four hydrophilic acrylic IOLs were studied, each with a centrally localized round opacification pattern associated with the intraocular use of gas. Laboratory analysis included gross examination with a light microscope, followed by alizarin and von Kossa staining. Optical quality was assessed by examining the modulation transfer function (MTF) and straylight. Results were compared with those of a control IOL and normative data for straylight of the crystalline lens. The following parameters were derived from image analysis: opacified surface fraction, light loss in the opacified surface, and the area and number of granules. The relationship between straylight increase and those parameters was studied. RESULTS: Fine granules were identified on the IOL surface and subsurface. The granules stained positive for calcium, and the MTF levels of 2 IOLs dropped markedly. The other 2 showed relatively minor changes. The straylight was extremely increased in 3 IOLs up to (and above) a level of that of a cataractous lens. A proportional relationship was found between straylight and the morphological parameters from image analysis. CONCLUSIONS: Intraocular lenses with centrally localized opacification have a strong potential for deteriorating optical performance. However, the optical quality might differ depending on the morphology of opacification. A serious straylight increase was found in most of these IOLs, suggesting that affected patients may suffer from glare-related symptoms.

Association between Contrast Sensitivity and Reading with Macular Pathology.

SIGNIFICANCE: Comparison between the role of spatial and temporal contrast sensitivities in the association with reading may provide insight into how visual tasks (such as reading) are related to primary optical or neural (or both) effects. More insight into primary visual factors influencing reading is important for understanding reading problems. PURPOSE: The aim of this study was to gain insight into the association between optical and neural components of contrast sensitivity (CS), operationalized as spatial CS (optical and neural) or temporal CS (solely neural), and reading speed in a clinical sample of participants with macular pathologies. The precision and agreement were also investigated. METHODS: The Mars test and temporal CS implementation of the C-Quant device were used to measure spatial CS and temporal CS, respectively. Tests were performed with 47 participants: mean age, 77 years (range, 52 to 92 years). Associations were investigated with correlations and linear regression models. Precision was defined by coefficients of repeatability. The 95% limits of agreement between spatial CS and temporal CS values were assessed. RESULTS: Reading speed correlated with both spatial CS (r = 0.35, P = .015) and temporal CS (r = 0.66, P < .001). After correction for visual acuity, central loss, and education level, the association between temporal CS and reading speed was not significant anymore. The coefficients of repeatability and reproducibility were 0.20 and 0.28 log unit (spatial CS) and 0.33 and 0.35 log unit (temporal CS), respectively. The values for temporal CS were 0.08 and 0.13 log unit higher than those for spatial CS. CONCLUSIONS: For spatial CS and temporal CS, moderate to strong correlations were found, respectively, with reading speed in patients with maculopathies. The stronger association between temporal CS and reading speed is suggested to reflect a high sensitivity for neural integrity of temporal CS. The differences in coefficients of repeatability and reproducibility could be explained by the psychometrical differences between methods.

Effects of Corneal Scars and Their Treatment With Rigid Contact Lenses on Quality of Vision.

OBJECTIVES: To study the effects of corneal scars and the treatment of these scars with rigid gas-permeable (RGP) contact lenses on quality of vision including straylight. Visual effects were related to scar characteristics such as size and grade. METHODS: Straylight and best-corrected visual acuity were measured in 23 patients with corneal scars during and after RGP contact lens wear. Contralateral eyes were used as controls, and age-normal values in case of bilateral scars. Straylight measurements were performed using the compensation comparison method of the Oculus C-Quant instrument. RESULTS: Scarred eye straylight values were 1.53 log(s) without contact lens and 1.60 log(s) with contact lens (P=0.043). Healthy eyes without contact lens had a mean straylight value of 1.13 log(s), corresponding to age-normal values. Contact lens wear increased straylight in healthy eyes to 1.26 log(s) (P<0.001). Visual acuity improved from 0.66 logarithm of minimal angle of resolution (logMAR) to 0.19 logMAR with contact lens wear in eyes with a corneal scar (P<0.001). CONCLUSIONS: Corneal scars can have a strong effect on quality of vision by diminishing visual acuity and increasing straylight. The increase in straylight from corneal scars on its own can lead to a serious visual handicap. Contact lens treatment did not improve straylight, but showed a slight worsening. As the recovery of visual acuity with contact lens wear far exceeded straylight increase, contact lenses remain a clinically useful treatment option in most patients with corneal scars.

Intraocular light scatter, reflections, fluorescence and absorption: what we see in the slit lamp.

PURPOSE: Much knowledge has been collected over the past 20 years about light scattering in the eye- in particular in the eye lens- and its visual effect, called straylight. It is the purpose of this review to discuss how these insights can be applied to understanding the slit lamp image. RESULTS: The slit lamp image mainly results from back scattering, whereas the effects on vision result mainly from forward scatter. Forward scatter originates from particles of about wavelength size distributed throughout the lens. Most of the slit lamp image originates from small particle scatter (Rayleigh scatter). For a population of middle aged lenses it will be shown that both these scatter components remove around 10% of the light from the direct beam. For slit lamp observation close to the reflection angles, zones of discontinuity (Wasserspalten) at anterior and posterior parts of the lens show up as rough surface reflections. All these light scatter effects increase with age, but the correlations with age, and also between the different components, are weak. For retro-illumination imaging it will be argued that the density or opacity seen in areas of cortical or posterior subcapsular cataract show up because of light scattering, not because of light loss. NOTES: (1) Light scatter must not be confused with aberrations. Light penetrating the eye is divided into two parts: a relatively small part is scattered, and removed from the direct beam. Most of the light is not scattered, but continues as the direct beam. This non-scattered part is the basis for functional imaging, but its quality is under the control of aberrations. Aberrations deflect light mainly over small angles (<1°), whereas light scatter is important because of the straylight effects over large angles (>1°), causing problems like glare and hazy vision. (2) The slit lamp image in older lenses and nuclear cataract is strongly influenced by absorption. However, this effect is greatly exaggerated by the light path lengths concerned. This obviates proper judgement of the functional importance of absorption, and hinders the appreciation of the Rayleigh nature of what is seen in the slit lamp image.

The significance of changes in pupil size during straylight measurement and with varying environmental illuminance.

PURPOSE: In this work, we investigated the pupillary conditions during straylight measurement, and the potential effect this might have on the measured straylight. METHODS: Five young (26-29-years-old) and 15 older (50-68-years-old) individuals participated in this study. First, the pupil diameter of both eyes was measured at three room illuminances. Next, straylight was assessed at two room illuminances. Simultaneously, the change in pupil size of the fellow eye was registered by a camera. RESULTS: Pupil size decreased with room illuminance and with age (both p<0.05). The dependency of pupil size on age decreased as room illuminance increased (0.018mm/year at 4 lux, 0.014mm/year at 40 lux, and 0.008mm/year at 400 lux illuminances). However, during straylight measurement, pupil sizes hardly differed between 4 and 40 lux illuminances. Respective pupil sizes corresponded with 399 and 451 lux adaptation on average. No statistically significant difference was found between the straylight under the two illuminances with average R2=0.85, p<0.05. CONCLUSION: We conclude that the illuminance of the examination room during straylight assessment does not affect the outcome in normal eyes. In fact, under mesopic and scotopic conditions, the luminance of the test field is so much higher than that of the room so that it determines the pupil size. Regardless of the lighting level, straylight measured in a laboratory, is valid for photopic pupils at an adaptation level corresponding with about 400 lux room illuminance.

Light scattering levels from intraocular lenses extracted from donor eyes.

PURPOSE: To assess light scatter levels of intraocular lenses (IOLs) extracted from donor eyes to understand straylight elevation documented earlier in pseudophakic population studies and identify potential sources of light scattering in IOLs. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Experimental study. METHODS: Light scattering in 74 donor IOLs was measured with the C-Quant device adapted for in vitro analysis of IOLs. Straylight was assessed at a 2.5-degree and 7.0-degree scatter angle, and results were compared with the straylight of a 20-year-old crystalline lens, a 70-year-old crystalline lens, and a lens with cataract. To identify potential changes to the IOL material, the IOLs were examined with a light microscope and a slitlamp. RESULTS: At 2.5 degrees and 7.0 degrees, the straylight parameter was 5.78 deg2/steradian (sr) ± 4.70 (SD) and 5.06 ± 4.01 deg2/sr, respectively. Forty-one percent of IOLs showed lower straylight than the 20-year-old lens. In 14%, the scattering intensity was higher than in the 70-year-old lens; none showed straylight comparable to that of the cataractous lens. Increased straylight was associated with surface deposits, snowflake-like degeneration, and glistenings. The incidence of IOL-related complications differed between the IOL groups. CONCLUSIONS: Microscopic structural alterations of IOLs play a major role in straylight elevations in pseudophakic eyes. A clear correlation with degeneration and/or alteration of implanted IOLs was found. Although these IOL-related complications would likely not affect visual acuity, they give rise to straylight and thus can cause disability glare and other symptoms.

Changes in Intraocular Straylight and Visual Acuity with Age in Cataracts of Different Morphologies.

PURPOSE: To investigate the significance of difference in straylight of cataract eyes with different morphologies, as a function of age and visual acuity. METHODS: A literature review to collect relevant papers on straylight, age, and visual acuity of three common cataract morphologies leads to including five eligible papers for the analysis. The effect of morphology was incorporated to categorize straylight dependency on the two variables. We also determined the amount of progression in a cataract group using a control group. RESULTS: The mean straylight was 1.22 log units ± 0.20 (SD) in nuclear (592 eyes), 1.26 log units ± 0.23 in cortical (776 eyes), and 1.48 log units ± 0.34 in posterior subcapsular (75 eyes) groups. The slope of straylight-age relationship was 0.009 (R2 = 0.20) in nuclear, 0.012 (R2 = 0.22) in cortical, and 0.014 (R2 = 0.11) in posterior subcapsular groups. The slope of straylight-visual acuity relationship was 0.62 (R2 = 0.25) in nuclear, 0.33 (R2 = 0.13) in cortical, and 1.03 (R2 = 0.34) in posterior subcapsular groups. CONCLUSION: Considering morphology of cataract provides a better insight in assessing visual functions of cataract eyes, in posterior subcapsular cataract, particularly, in spite of notable elevated straylight, visual acuity might not manifest severe loss.

Validation of a spectral light scattering method to differentiate large from small particles in intraocular lenses.

A psychophysical approach has been designed to measure straylight from intraocular lenses (IOLs) in vitro. This approach uses a clinical straylight meter (C-Quant) and an observer's eye as optical detector. Based on this, we introduced a method for study of straylight-wavelength dependency for IOLs. This dependency can be used to distinguish between 2 types of scattering particles (small and large) as defined by Mie theory. Validation was performed using a turbidity standard and scattering filters. Several IOLs were analyzed to identify potential scattering sources. Large particles were found to predominate in scattering from the studied lenses. This was confirmed by straylight-angular dependency found in these IOLs.

The (lack of) relation between straylight and visual acuity. Two domains of the point-spread-function.

PURPOSE: The effect of cataract and other media opacities on functional vision is typically assessed clinically using visual acuity. In both clinical and basic research, straylight (the functional result of light scattering in the eye) is commonly measured. The purpose of the present study was to determine the link between these two measures: is visual acuity in cataract and other media opacities related to straylight? METHODS: Interdependence between acuity and straylight is addressed from three different points of view: (1) Methodological: can acuity differences affect the measurement value of straylight, and vice versa? (2) Basic optics: does the optical process of light scattering in the human eye affect both straylight and visual acuity? (3) Statistical: how strongly are acuity and straylight correlated in the practice of important clinical conditions? Experimental and theoretical aspects will be considered, with a focus on normal ageing and cataract formation. RESULTS: (1) Methodological: testing potential effects of acuity, artificially manipulated with positive trial lenses, showed no effect on measured straylight values. Since light scattering in the eye involves a low percentage of the light and has large angular spreading, contrast reduction due to straylight is limited, resulting in virtually absent acuity effects. (2) Basic optics: light scattering from the human donor eye lens is found to have virtually no effect in the centre of the point-spread-function, also for cataractous lenses, resulting in virtually absent acuity effects. (3) Statistical: literature data on straylight and visual acuity show a weak correlation for the important groups of normal ageing and cataract populations. CONCLUSIONS: The point-spread-function of the normal ageing and cataractous human eye is built upon two rather independent basic parts. Aberrations control the central peak. Light scattering controls the periphery from about 1° onwards. The way acuity and straylight are measured ensures no confounding between them. Statistically within the normal ageing and cataract populations, visual acuity and straylight vary quite independently from each other. Visual acuity losses with cataract and other media opacities are not due to straylight, but caused by aberrations and micro-aberrations. Straylight defines disability glare, and causes symptoms of glare, haloes, hazy vision etc. Overall, visual acuity and straylight are rather independent aspects of quality of vision.

Straylight from glistenings in intraocular lenses: In vitro study.

PURPOSE: To assess light scattering from intraocular lenses (IOLs) with different numbers of laboratory-induced glistenings and create a model for predicting glistening effects on straylight. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Experimental study. METHODS: Glistenings were induced in 7 Acrysof IOLs using an accelerated aging method. To create different numbers of glistenings, the IOLs were immersed in a balanced salt solution at temperatures ranging from 37°C to 60°C and cooled to room temperature. The glistenings were analyzed with a microscope. Light scattering from the IOLs was assessed using a commercial straylight meter (C-Quant) adapted for in vitro evaluation of IOLs at a 2.5-degree and 7.0-degree scatter angle. A model was proposed relating straylight increase to the total number and surface portion (total number × area) of glistenings. Results were compared to the Mie theory. RESULTS: The number of induced glistenings ranged from 114 to 12 386 per mm2, and the surface portion ranged from 1.4% to 26.9%. At 2.5 degrees, the range in the straylight parameter was 1.49 to 72.49 deg2/steradian (sr); at 7.0 degrees, it was 1.72 to 62.87 deg2/sr. Straylight was proportionally related to the total number of glistenings (0.0046 × total number) (R2 = 0.96) and the surface portion (217 × surface portion) (R2 = 0.97). The measurements agreed well with Mie theory. CONCLUSIONS: Straylight from glistenings in IOLs had an accurate proportional association with their total number and surface portion. The proposed model proved effective in predicting straylight from glistenings. Numerous glistenings are needed to cause significant straylight elevation.

Straylight as an Indicator for Cataract Extraction in Patients with Retinal Dystrophy.

PURPOSE: Straylight reduces retinal sensitivity, which is particularly relevant in conditions with retinal dysfunction, such as retinitis pigmentosa (RP). Retinitis pigmentosa is associated with posterior subcapsular cataract (PSC), a cataract type that is known to cause severe disability glare (i.e., straylight). Study purposes were (1) to determine the severity of disability glare before and after cataract extraction (CE) in subjects with retinal dystrophy; (2) to study possible aggravation of disability glare due to the combination of retinal degradation and increased straylight from PSC; and (3) to evaluate whether straylight can be used to support the possible benefit of (early) CE. DESIGN: Prospective, comparative study. PARTICIPANTS: Sixteen patients (25 eyes) with retinal dystrophy scheduled for CE participated. METHODS: Cataract severity was graded according to the Lens Opacities Classification System (LOCS) III. Preoperatively and postoperatively, corrected distance visual acuity (CDVA), spatial contrast sensitivity with the Pelli-Robson chart, and straylight were tested. Retinal function was assessed with Goldmann visual field and temporal contrast sensitivity (TCS). Temporal contrast sensitivity is a flicker test to evaluate central retinal sensitivity isolated from the eye's optical quality. Central retinal structure was assessed with spectral-domain OCT and fundus autofluorescence. MAIN OUTCOME MEASURES: Preoperative and postoperative straylight were measured using the C-Quant (Oculus Optikgeräte GmbH, Wetzlar, Germany) and expressed as the logarithm of the straylight parameter s: log(s). RESULTS: The average straylight value was 1.75 preoperatively and 1.45 postoperatively, 7.1 and 3.5 times higher than in a healthy young eye, respectively. Functionally significant improvement, defined as >0.20 log, was found in 72% of eyes for straylight and in 20% of eyes for CDVA. The CDVA and TCS were significantly correlated. Only straylight improvement was related to preoperative values; therefore, straylight was the only parameter that could be used to support postoperative improvement. In retinal dystrophy, eyes with cataract and a preoperative straylight value ≥1.66 log(s), a 50% chance of functionally significant log(s) improvement can be expected. CONCLUSIONS: In patients with retinal dystrophy, straylight caused by cataract substantially aggravates visual disability, whereas CDVA is less affected. Therefore, straylight is a valuable (additional) indicator for beneficial CE in patients with retinal dystrophy and cataract.