From Presbyopia to Cataracts: A Critical Review on Dysfunctional Lens Syndrome

BCLA CLEAR Presbyopia: Management with corneal techniques

Corneal techniques for enhancing near and intermediate vision to correct presbyopia include surgical and contact lens treatment modalities. Broad approaches used independently or in combination include correcting one eye for distant and the other for near or intermediate vision, (termed monovision or mini-monovision depending on the degree of anisometropia) and/or extending the eye's depth of focus [1]. This report provides an overview of the evidence for the treatment profile, safety, and efficacy of the range of corneal techniques currently available for managing presbyopia. The visual needs and expectations of the patient, their ocular characteristics, and prior history of surgery are critical considerations for patient selection and preoperative evaluation. Contraindications to refractive surgery include unstable refraction, corneal abnormalities, inadequate corneal thickness for the proposed ablation depth, ocular and systemic co-morbidities, uncontrolled mental health issues and unrealistic patient expectations. Laser refractive options for monovision include surface/stromal ablation techniques and keratorefractive lenticule extraction. Alteration of spherical aberration and multifocal ablation profiles are the primary means for increasing ocular depth of focus, using surface and non-surface laser refractive techniques. Corneal inlays use either small aperture optics to increase depth of field or modify the anterior corneal curvature to induce corneal multifocality. Presbyopia correction by conductive keratoplasty involves application of radiofrequency energy to the mid-peripheral corneal stroma which leads to mid-peripheral corneal shrinkage, inducing central corneal steepening. Hyperopic orthokeratology lens fitting can induce spherical aberration and correct some level of presbyopia. Postoperative management, and consideration of potential complications, varies according to technique applied and the time to restore corneal stability, but a minimum of 3 months of follow-up is recommended after corneal refractive procedures. Ongoing follow-up is important in orthokeratology and longer-term follow-up may be required in the event of late complications following corneal inlay surgery.

Screening of positive dysphotopsia before multifocal intraocular lens implantation

PURPOSE

To assess the photic phenomena (PP) and positive dysphotopsia in candidates for presbyopia or cataract surgery and to evaluate their relationship with cataract grading systems.

DESIGN

Retrospective observational.

METHODS

Monocular data for 82 subjects measured during the preoperative screening were retrospectively retrieved from our database. The evaluated variables consisted of two methods for PP measurement: light distortion index (LDI) and parameters obtained from a simulator, both of which were combined with subjective bother related to PP. The cutoff for LDI that better predicted patients passing from slightly to moderately bothersome was estimated. The relationships between LDI and the following objective cataract grading methods were also assessed: objective scatter index (OSI), dysfunctional lens index (DLI), and Pentacam Nucleus Staging (PNS).

RESULTS

LDI was the best method for measuring PP, which showed a significant correlation with the bothersome question (rho = 0.34, P = 0.002) and also with OSI (rho = 0.67, P < 0.0005), DLI (rho = -0.29, P = 0.007), and PNS (rho = 0.48, P < 0.0005). The number/percentage of patients who found it bothersome was as follows: "Not at all" (18/22%), "Slightly" (41/50%), "Moderately" (15/18.3%), and "Very" (8/9.7%). The cutoff value that predicted the transition from slightly to moderately bothersome was ≥15.20% according to LDI, which could be estimated with the following values for grading: ≥2.8 for OSI, ≤7.6 for DLI, and ≥2 for PNS.

CONCLUSIONS

Patients reporting moderately or higher bothersome levels in the preoperative period and with LDI <15.20%, <2.8 for OSI, >7.6 for DLI, and <2 for PNS might deserve special attention in the multifocal intraocular lens selection.

Simulations of Multifocal Vision in Patients With Previous Monofocal Intraocular Lens Implantation

PURPOSE

To evaluate the effectiveness and patient acceptance of multifocal vision simulation in patients with previous monofocal intraocular lens (IOL) implantation, and to explore their willingness-to-pay (WTP) and willingness-to-accept (WTA) based on the perceived advantages and disadvantages of multifocal vision.

METHODS

Seventeen patients with previous monofocal IOL implantation participated in this cross-sectional study. The SimVis Gekko device (2EyesVision SL) was used to simulate monofocal (Evaluation B) and multifocal (Evaluation C) visual experiences, compared to their existing vision (Evaluation A). Visual acuity at three distances and defocus curves were measured. Patients responded to inquiries about visual quality in each evaluation, bothersomeness of photic phenomena, probability to select the visual experience, and the monetary value they associated with enhanced WTP or diminished WTA visual quality.

RESULTS

The simulations underestimated the visual acuity reported for the IOL in existing literature by one or two lines, depending on the testing distance. This underestimation was more pronounced in defocus curves. However, 70.6% of patients were likely or very likely to opt for multifocal vision, indicating they perceived the benefits of multifocality. The WTP for multifocal vision was twice that of monofocal vision, and the WTP/WTA ratio exceeded 1, suggesting the perceived vision benefits outweighed potential drawbacks.

CONCLUSIONS

Despite underestimating the expected postoperative visual performance, the multifocal simulation enabled patients to perceive the benefits of multifocal vision to some extent. This system could be beneficial in avoiding potential postoperative complaints, but the possible rise in false-positive results should be considered and evaluated in future research. [J Refract Surg. 2023;39(12):831-839.].

Objective cataract grading methods and expected contrast sensitivity reestablishment with multifocal intraocular lenses

PURPOSE

To determine the cut-off points for age and metrics provided by cataract grading objective systems for which a reestablishment in contrast sensitivity (CS) is expected after multifocal intraocular lens (MIOL) implantation.

METHODS

One hundred seven subjects were included in this retrospective analysis carried out during the screening for presbyopia and cataract surgery. Monocular distance corrected contrast sensitivity defocus curve (CSDC) and visual acuity were measured, and crystalline lens sclerosis was graded with three objective metrics: Ocular Scatter Index (OSI), Dysfunctional Lens Index (DLI) and Pentacam Nucleus Staging (PNS). A CS value of 0.8 logCS at far distance, following published literature on this matter, was selected to compute the cut-off that maximized the detection of eyes exceeding this value at the preoperative screening, either for age or objective metrics.

RESULTS

The CDCS showed a stronger correlation than CDVA with objective grading methods, whereas all objective metrics were significantly correlated between them (p < 0.05). The cut-offs for age, OSI, DLI and PNS were ≤ 62, ≤ 1.25, ≥ 7.67 and ≤ 1, respectively. The OSI provided the highest area under the receiver operating characteristic curve (0.85) followed by the age (0.84), DLI (0.74) and PNS (0.63).

CONCLUSIONS

Surgeons conducting clear lens exchange should communicate the possible distance CS loss after surgery with MIOL implantation according to the previous described cut-offs points. Age in combination with any cataract grading objective system is recommended to detect possible inconsistencies.

Influence of a multifocal intraocular lens centration and eye angles on light distortion and ocular scatter index

PURPOSE

To assess how eye axes and multifocal intraocular lens (MIOL) centration may impact the light distortion index (LDI) and ocular scatter index (OSI).

METHODS

Fifty-eight subjects implanted with the trifocal MIOL Q-Flex M 640PM or Liberty 677MY (Medicontur) were included in this retrospective analysis. The following variables were collected with the Pentacam Wave (Oculus) considering the vertex normal as the coordinates center: chord-mu to the center of the pupil, chord-alpha to the geometrical center of the cornea, and chord-MIOL to the center of the diffractive ring. These measurements were correlated with OSI (HD Analyzer, Visiometrics) and LDI (light distortion analyzer, CEORLab).

RESULTS

Chord-MIOL centroid was 0.12 mm at 62°, chord-mu was 0.09 mm at 174°, and chord-alpha was 0.38 mm at 188°. A relationship was found between OSI and LDI, rho = 0.58, p < 0.0005). No relationships were found between chord-mu or chord-alpha and the LDI or OSI, neither for the total magnitude, nor the decomposition in orthogonal components (p > 0.05). The LDI was significantly correlated with the temporal centration of the MIOL versus the vertex normal (rho = 0.32, p = 0.02).

CONCLUSIONS

As opposed to what has been previously described, the temporal centration of the MIOL was related to a decrease in the LDI. Future studies with extreme values of the included variables are required to establish cut-offs for considering these variables as exclusion criteria in the implantation of a MIOL.

Visual and patient-reported outcomes of a diffractive trifocal intraocular lens in highly myopic eyes: a prospective multicenter study

BACKGROUND

To investigate the visual and patient-reported outcomes of a diffractive trifocal intraocular lens (IOL) in highly myopic eyes.

METHODS

Patients with planned cataract removal by phacoemulsification and implantation of a trifocal IOL (AT LISA tri 839MP) were enrolled in the prospective, multicenter cohort study. Patients were allocated into three groups according to their axial length (AL): control group, AL < 26 mm; high myopia group, AL 26-28 mm; extreme myopia group, AL ≥ 28 mm. At 3 months post-surgery, data for 456 eyes of 456 patients were collected, including visual acuity, defocus curve, contrast sensitivity (CS), visual quality, spectacle independence, and overall satisfaction.

RESULTS

After surgery, the uncorrected distance visual acuity improved from 0.59 ± 0.41 to 0.06 ± 0.12 logMAR (P < 0.001). In all three groups, about 60% of eyes achieved uncorrected near and intermediate visual acuity of 0.10 logMAR or better, but significantly fewer eyes in the extreme myopia group achieved uncorrected distance visual acuity of 0.10 logMAR or better (P < 0.05). Defocus curves revealed that the visual acuity was significantly worse in the extreme myopia group than others at 0.00, - 0.50, and - 2.00 diopters (P < 0.05). CS did not differ between the control and high myopia groups but was significantly lower in the extreme myopia group at 3 cycles per degree. The extreme myopia group also had greater higher-order aberrations and coma, lower modulation transfer functions and VF-14 scores, more glare and halos, worse spectacle independence at far distance, and consequently lower patient satisfaction than others (all P < 0.05).

CONCLUSIONS

In eyes with a high degree of myopia (AL < 28 mm), trifocal IOLs have been shown to provide similar visual outcomes to those in non-myopic eyes. However, in extremely myopic eyes, acceptable results may be obtained with trifocal IOLs, but a reduced level of uncorrected distance vision is expected.

In situ assessment of lens elasticity with noncontact optical coherence elastography

Lens biomechanics has great potential for application in clinical diagnostics and treatment monitoring of presbyopia and cataracts. However, current approaches to lens elastography do not meet the desired safety or sensitivity for clinical application. In this regard, we propose a noncontact optical coherence elastography (OCE) method to facilitate quantitative in situ imaging of lens elasticity. Elastic waves induced by air-pulse stimulation on the limbus propagate to the lens and are then imaged using custom-built swept-source optical coherence tomography to obtain the elastic wave velocity and Young's modulus. The proposed OCE method was first validated by comparing the results of in situ and in vitro measurements of porcine lenses. The results demonstrate that the Young's modulus measured in situ was highly consistent with that measured in vitro and had an intraclass correlation coefficient of 0.988. We further investigated the elastic changes induced by cold storage and microwave heating. During 36-hour cold storage, the mean Young's modulus gradually increased (from 5.62 ± 1.24 kPa to 11.40 ± 2.68 kPa, P < 0.0001, n = 9) along with the formation of nuclear opacities. 15-second microwave heating caused a greater increase in the mean Young's modulus (from 6.86 ± 1.21 kPa to 25.96 ± 8.64 kPa, P < 0.0025, n = 6) without apparent cataract formation. Accordingly, this study reports the first air-pulse OCE measurements of in situ lenses, which quantified the loss of lens elasticity during simulated cataract development with good repeatability and sensitivity, thus enhancing the potential for adoption of lens biomechanics in the clinic.

Visual performance, safety and patient satisfaction after bilateral implantation of a trifocal intraocular lens in presbyopic patients without cataract

Background

The aim was to evaluate the safety and efficacy of a trifocal intraocular lens (IOL) for the correction of presbyopia and to assess patient satisfaction.

Methods

Records from three centres were reviewed to select presbyopic patients having undergone bilateral refractive lens exchange and implantation of the AT LISA tri 839MP multifocal IOL. Postoperatively, monocular and binocular distance, intermediate and near visual acuities, corrected and uncorrected, and subjective refraction were measured. Patients also completed a quality of life questionnaire. Safety evaluation included IOL stability and postoperative complications.

Results

72 eyes (36 patients) were analysed. No clinically significant difference between pre- and postoperative corrected distance visual acuity (CDVA) was found for monocular or binocular measurements. Mean postoperative monocular CDVA was 0.02 ± 0.04 logMAR. Mean refractive values all improved statistically significantly compared with preoperative baseline (p ≤ 0.0064). Overall, 82.4% of eyes had spherical equivalent within ± 0.5 D and 97.1% within ± 1.0 D of emmetropia with a mean accuracy of -0.10 ± 0.41 D. Spectacle independence for distance, intermediate and near visual acuity was 87.5%, 84.4% and 78.1% respectively, and 78.1% of patients were satisfied with their postoperative, spectacle-free vision. Eight eyes received Nd:YAG laser treatment. No other IOL-related safety issues were reported.

Conclusion

AT LISA tri 839MP multifocal IOL bilaterally implanted in presbyopic patients provided excellent distance, intermediate and near visual outcomes with very accurate correction of refraction. These results were associated with a high level of spectacle independence and patient satisfaction.

Trial registration

Trial registered on https://clinicaltrials.gov/ under the identification NCT03790592 (31/12/2018).

Characterization of Dysfunctional Lens Index and Opacity Grade in a Healthy Population

This study enrolled 61 volunteers (102 eyes) classified into subjects < 50 years (group 1) and subjects ≥ 50 years (group 2). Dysfunctional Lens Index (DLI); opacity grade; pupil diameter; and corneal, internal, and ocular higher order aberrations (HOAs) were measured with the i-Trace system (Tracey Technologies). Mean DLI was 8.89 ± 2.00 and 6.71 ± 2.97 in groups 1 and 2, respectively, being significantly higher in group 1 in all and right eyes (both p < 0.001). DLI correlated significantly with age (Rho = −0.41, p < 0.001) and pupil diameter (Rho = 0.20, p = 0.043) for all eyes, and numerous internal and ocular root-mean square HOAs for right, left, and all eyes (Rho ≤ −0.25, p ≤ 0.001). Mean opacity grade was 1.21 ± 0.63 and 1.48 ± 1.15 in groups 1 and 2, respectively, with no significant differences between groups (p ≥ 0.29). Opacity grade significantly correlated with pupil diameter for right and all eyes (Rho ≤ 0.33, p ≤ 0.013), and with some ocular root-mean square HOAs for right and all eyes (Rho ≥ 0.23, p ≤ 0.020). DLI correlates with age and might be used complementary to other diagnostic measurements for assessing the dysfunctional lens syndrome. Both DLI and opacity grade maintain a relationship with pupil diameter and internal and ocular HOAs, supporting that the algorithms used by the device may be based, in part, on these parameters.

Mesopic Disability Glare in Stage-Two Dysfunctional Lens Syndrome

Introduction

There is a lack of evidence about the exact deterioration of visual function associated with the age-related natural changes in the lens, particularly in intermediate (stage-2) dysfunctional lens syndrome (DLS). Standard photopic visual acuity and contrast sensitivity tests may not show the visual worsening in daily life activities, such as oncoming vehicle headlights at night. The purpose of this study was to analyze visual function under different conditions and glare sources in stage-2 DLS.

Methods

Forty patients over 49 years of age with initial bilateral lens opacification (Lens Opacities Classification System III [LOCS-III] scores up to 3), best-corrected visual acuity of 20/25 or better, and no ocular disease were evaluated. Binocular photopic and mesopic contrast sensitivity (CS) with/without halogen and xenon increasing glare sources were analyzed. Mesopic disability glare (MDG) was calculated as the difference between mesopic CS with/without the glare source.

Results

The median logarithmic CS (logCS) values were lower under mesopic conditions (1.05) than under photopic illumination (1.65; P < 0.001). Halogen and xenon glare further decreased mesopic CS (both, median logCS 0.75, P < 0.001). The mean MDG was 0.31 ± 0.10 log units for halogen glare and 0.33 ± 0.09 log units for xenon glare. The mesopic CS and MDG were not associated with any photopic test. The mesopic CS with glare but not photopic CS or mesopic CS was correlated with the LOCS-III scores. The best association was provided by MDG, which showed a pooled correlation with LOCS-III nuclear opalescence (r = 0.411, P < 0.001) and cortical scores (r = 0.226, P = 0.04).

Conclusion

The mesopic CS under a glare source is an independent early indicator of visual impairment in stage-2 DLS patients, and appears to be substantial. Furthermore, the MDG is more sensitive than photopic and mesopic CS for evaluating patients with initial phacosclerosis. Surgeons should consider this in the decision-making process of the correct timing for lens surgery.

Posterior capsular opacification evaluation through contrast sensitivity defocus curves with two multifocal intraocular lenses of similar material

PURPOSE

To assess the degree of posterior capsular opacification (PCO) and its influence on contrast sensitivity defocus curve (CSDC) after implantation of two trifocal intraocular lenses (IOLs), Alsafit (AT) and Liberty (L), during a 12-month follow-up. A secondary aim was to evaluate the Nd:YAG capsulotomy rate in a long time.

METHODS

Data from 63 subjects, 34 implanted with AT and 29 with L, were retrospectively analyzed for this pilot study. In those eyes without capsulotomy during the first year (n = 58), CSDC at 3 and 12 months after surgery and PCO grading were measured, with additional answering of a visual function questionnaire (VF-14) and a question of general satisfaction. The period after surgery up to capsulotomy or last on-demand visit without Nd:YAG was recorded for survival analysis beyond the 12-month follow-up.

RESULTS

Total area under CSDC (TAUC) between 3 and 12 months decreased from 2.96 to 1.71 for AT (p < 0.05) and from 2.73 to 2.21 (p > 0.05) for L. Of eyes, 51.6, 19.3, and 29% with AT were graded as level 0, 1, and 2 of PCO, while 85.1, 11.1, and 3.7% of eyes with L were graded as level 0, 1, and 2 (p < 0.05). PCO grading was correlated with a decrease of TAUC (ρ =  - 0.27, p = 0.04). Median time to require capsulotomy was 22 months with AT and 30 months with L (p < 0.05).

CONCLUSIONS

PCO decreases CSDC in patients with trifocal lenses. Despite using the same hydrophilic material, PCO grading and Nd:YAG capsulotomy rate was higher for AT than for L.

PresbyLASIK: A review of PresbyMAX, Supracor, and laser blended vision: Principles, planning, and outcomes

PresbyLASIK is one of the most commonly used modalities of surgical correction in presbyopes with no cataract. Unlike monovision procedures, both the eyes are adjusted for near and distance, providing a good stereopsis. This works by creating a corneal multifocality and increasing the depth of focus. Most techniques of presbyLASIK currently employ hybrid methods, i.e., a component of monovision added on to a multifocal corneal ablation. Choosing an appropriate proportion of these two components according to the patients' requirements and meticulous patient selection are key to obtaining desirable outcomes. Being corneal-based procedures, presbyLASIK has shown to be reversible. Thorough updated knowledge of the different presbyLASIK procedures, their principles and outcomes based on previous studies is required before a refractive surgeon plans to start providing presbyLASIK services. We performed a comprehensive search on PubMed with the keywords "Presbyopia surgery," "PresbyLASIK" "PresbyMAX," "Supracor," and "Custom-Q." In this review article, we have explained the principles of the various presbyLASIK procedures, appropriate patient selection and planning on the devices with examples, and summarized the previously published outcomes of these techniques.

Effect of Alpha-Glucosyl-Hesperidin Consumption on Lens Sclerosis and Presbyopia

Presbyopia is characterized by a decline in the ability to accommodate the lens. The most commonly accepted theory for the onset of presbyopia is an age-related increase in the stiffness of the lens. However, the cause of lens sclerosis remains unclear. With age, water microcirculation in the lens could change because of an increase in intracellular pressure. In the lens, the intracellular pressure is controlled by the Transient Receptor Potential Vanilloid (TRPV) 1 and TRPV4 feedback pathways. In this study, we tried to elucidate that administration of α-glucosyl-hesperidin (G-Hsd), previously reported to prevent nuclear cataract formation, affects lens elasticity and the distribution of TRPV channels and Aquaporin (AQP) channels to meet the requirement of intracellular pressure. As a result, the mouse control lens was significantly toughened compared to both the 1% and 2% G-Hsd mouse lens treatments. The anti-oxidant levels in the lens and plasma decreased with age; however, this decrease could be nullified with either 1% or 2% G-Hsd treatment in a concentration- and exposure time-dependent manner. Moreover, G-Hsd treatment affected the TRPV4 distribution, but not TRPV1, AQP0, and AQP5, in the peripheral area and could maintain intracellular pressure. These findings suggest that G-Hsd has great potential as a compound to prevent presbyopia and/or cataract formation.

Review of current status of refractive lens exchange and role of dysfunctional lens index as its new indication

Advances in phacodynamics and intraocular lenses (IOLs) has given second life to clear lens extraction (CLE) or refractive lens exchange (RLE) in recent years for the treatment of patients with high degrees of myopia, hyperopia, and astigmatism who are unsuitable for laser surgery. Furthermore, presbyopia treatment with RLE supplemented with multifocal or accommodating IOLs gives the dual benefit of correcting refractive errors with eliminating the need for cataract surgery. RLE should be consistent and effective for a good refractive outcome along with safety during the surgical procedure and in the postoperative period. Therefore, proper patient selection and accurate preoperative protocols for IOL power calculations and selection are important along with an appropriate choice of surgical procedure. Dysfunctional lens index is a new objective tool that helps surgeon to aid in diagnosing, counseling, and educating patients with dysfunctional clear lens. In this article, we give a brief overview about the application of RLE for individuals with presbyopia and refractive errors like myopia, hyperopia, and astigmatism who are not suitable for laser correction.

Standard Results and Contrast Sensitivity Reestablishment after Implantation of a Trifocal Intraocular Lens

PURPOSE/AIM

To assess, following the standards, the results of safety, efficacy and predictability for a trifocal intraocular lens and to evaluate contrast sensitivity and visual acuity defocus curve.

MATERIALS AND METHODS

Fifty subjects operated on cataract surgery or refractive lens exchange with a trifocal intraocular lens have been recruited for the study. The monocular uncorrected visual acuity (VA) at far, intermediate (67 cm) and near (40 cm) distances in addition to corrected VA at far and near distances was evaluated at 1 week, 1 month and 3 months after surgery. Postoperative refraction, binocular contrast sensitivity function (CSF) and binocular defocus curves were also collected at the 3-month follow-up visit.

RESULTS

Mean uncorrected VA was 0.10, 0.07 and 0.05 logMAR at far, intermediate and near distances. Corrected distance VA at far and near distances was 0.04 and 0.02 logMAR. Ninety percent and 100% achieved a spherical equivalent in ±0.50 D and ±1.00 D, respectively. CSF was above normal range for 12 and 18 cycles per degree (cpd) in all the conditions, inside the normal range in 1.5, 3 and 6 cpd and only decreased below normal range for 1.5 and 3 cpd in mesopic vision without glare.

CONCLUSIONS

The procedure achieved a safety, efficacy and predictability similar to those reported by previous studies. The CSF was generally enhanced after the procedure in comparison to those reported in non-operated subjects above 60 years old. Previous studies might underestimate the effective distance of the intermediate and near foci.

Multimodal quantitative optical elastography of the crystalline lens with optical coherence elastography and Brillouin microscopy

Assessing the biomechanical properties of the crystalline lens can provide crucial information for diagnosing disease and guiding precision therapeutic interventions. Existing noninvasive methods have been limited to global measurements. Here, we demonstrate the quantitative assessment of the elasticity of crystalline lens with a multimodal optical elastography technique, which combines dynamic wave-based optical coherence elastography (OCE) and Brillouin microscopy to overcome the drawbacks of individual modalities. OCE can provide direct measurements of tissue elasticity rapidly and quantitatively, but it is a challenge to image transparent samples such as the lens because this technique relies on backscattered light. On the other hand, Brillouin microscopy can map the longitudinal modulus with micro-scale resolution in transparent samples. However, the relationship between Brillouin-deduced modulus and Young's modulus is not straightforward and sample dependent. By combining these two techniques, we can calibrate Brillouin measurements with OCE, based on the same sample, allowing us to completely map the Young's modulus of the crystalline lens. The combined system was first validated with tissue-mimicking gelatin phantoms of varying elasticities (N = 9). The OCE data was used to calibrate the Brillouin shift measurements and subsequently map the Young's modulus of the phantoms. After validation, OCE and Brillouin measurements were performed on ex-vivo porcine lenses (N = 6), and the Young's modulus of the lenses was spatially mapped. The results show a strong correlation between Young's moduli measured by OCE and longitudinal moduli measured by Brillouin microscopy. The correlation coefficient R was 0.98 for the phantoms and 0.94 for the lenses, respectively. The mean Young's modulus of the anterior and posterior lens was 1.98 ± 0.74 kPa and 2.93 ± 1.13 kPa, respectively, and the Young's modulus of the lens nucleus was 11.90 ± 2.94 kPa. The results presented in this manuscript open a new way for truly quantitative biomechanical mapping of optically transparent (or low scattering) tissues in 3D.

Intraocular scattering as a predictor of driving performance in older adults with cataracts

Cataracts can limit a person’s ability to perform vision-dependent tasks safely, affecting the quality of life of older people. This study examines the relationship between visual function and driving, by studying which visual parameters might be important for predicting driving performance in older drivers with and without cataracts, ascertaining whether the objective measurement of intraocular scattering should be considered in assessment procedures for older drivers. This cross-sectional study involved a total of 20 older drivers (10 patients with bilateral cataracts and 10 control subjects). All participants were examined for visual acuity, contrast sensitivity, visual discrimination capacity, and intraocular scattering. Driving performance was also tested using a driving simulator. To study the relationship between visual parameters and driving performance, a correlation analysis and regression model were used. Drivers with cataracts showed a significantly impaired (p<0.05) visual function, with an Objective Scattering Index (OSI) 3.5 times greater than the control group. Driving performance was also significantly worse (p<0.05) in drivers with cataracts, reflected by a notable deterioration in lane keeping. The correlation analysis showed significant associations between driving performance and all the visual parameters studied. Finally, the regression model revealed that the OSI was the best predictor of driving performance, accounting for 51.3% of its variance. Visual function and driving performance are markedly deteriorated when cataracts are present. Our results demonstrate that the objective scattering index (OSI) has a high predictive power when it comes to simulated driving performance in older drivers, both with and without cataracts, suggesting that scatter measurements could be important in helping better understand visual limitations in older drivers.