Critical Flicker Frequency as a Potential Vision Technique in the Presence of Cataracts

Trichromatic critical flicker frequency as potential visual test in cataract and macula disease patients

PURPOSE

To investigate the capacity of critical flicker frequency (CFF) in discriminating cataract eyes with or without macula disease using trichromatic flickers, and to develop a model to predict postoperative best corrected visual acuity (BCVA).

METHODS

Patients were divided into two groups based on the presence or absence of macular disease. CFF threshold measurements of red (R-CFF), green (G-CFF), and yellow (Y-CFF) flickers were conducted both preoperatively and postoperatively. A generalized estimating equations model (GEE) was employed to examine the relationship between CFF threshold and 3-month postoperative BCVA.

RESULTS

A total of 115 eyes were enrolled, with 59 eyes in the cataract alone group and 56 eyes in the cataract with macular disease group completing the follow-up. R-CFF was found to be consistent before and after cataract removal (P = 0.06), even in cases where OCT was not performed successfully (P > 0.05). Y-CFF showed the highest AUC (0.798) for differentiating ocular comorbidities. According to the GEE model, in patients with a CFF threshold below 26 Hz, the odds ratios for achieving a postoperative VA of 20/40 or better were 34.8% for R-CFF, 26.0% for G-CFF, and 24.5% for Y-CFF.

CONCLUSION

CFF emerges as a promising tool for predicting postoperative BCVA, providing valuable supplementary insights when fundus examination is obstructed. R-CFF demonstrates the best resistance to cataracts, while Y-CFF exhibits the highest sensitivity both in identifying macular diseases and predicting postoperative BCVA of 20/40 or better.

Comment on Muth et al. Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review. Medicina 2023, 59, 800

We first want to thank the authors of the excellent review for their contributions to summarizing the confounders associated with critical flicker fusion frequency (CFFF) [...].

Prediction of postoperative visual acuity in patients with age-related cataracts using macular optical coherence tomography-based deep learning method

Background

To predict postoperative visual acuity (VA) in patients with age-related cataracts using macular optical coherence tomography-based deep learning method.

Methods

A total of 2,051 eyes from 2,051 patients with age-related cataracts were included. Preoperative optical coherence tomography (OCT) images and best-corrected visual acuity (BCVA) were collected. Five novel models (I, II, III, IV, and V) were proposed to predict postoperative BCVA. The dataset was randomly divided into a training (n = 1,231), validation (n = 410), and test set (n = 410). The performance of the models in predicting exact postoperative BCVA was evaluated using mean absolute error (MAE) and root mean square error (RMSE). The performance of the models in predicting whether postoperative BCVA was improved by at least two lines in the visual chart (0.2LogMAR) was evaluated using precision, sensitivity, accuracy, F1 and area under curve (AUC).

Results

Model V containing preoperative OCT images with horizontal and vertical B-scans, macular morphological feature indices, and preoperative BCVA had a better performance in predicting postoperative VA, with the lowest MAE (0.1250 and 0.1194LogMAR) and RMSE (0.2284 and 0.2362LogMAR), and the highest precision (90.7% and 91.7%), sensitivity (93.4% and 93.8%), accuracy (88% and 89%), F1 (92% and 92.7%) and AUCs (0.856 and 0.854) in the validation and test datasets, respectively.

Conclusion

The model had a good performance in predicting postoperative VA, when the input information contained preoperative OCT scans, macular morphological feature indices, and preoperative BCVA. The preoperative BCVA and macular OCT indices were of great significance in predicting postoperative VA in patients with age-related cataracts.

Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review

The critical flicker fusion frequency (cFFF) refers to the frequency at which a regularly recurring change of light stimuli is perceived as steady. The cFFF threshold is often assessed in clinics to evaluate the temporal characteristics of the visual system, making it a common test for eye diseases. Additionally, it serves as a helpful diagnostic tool for various neurological and internal diseases. In the field of diving/hyperbaric medicine, cFFF has been utilized to determine alertness and cognitive functions. Changes in the cFFF threshold have been linked to the influence of increased respiratory gas partial pressures, although there exist inconsistent results regarding this effect. Moreover, the use of flicker devices has produced mixed outcomes in previous studies. This narrative review aims to explore confounding factors that may affect the accuracy of cFFF threshold measurements, particularly in open-field studies. We identify five broad categories of such factors, including (1) participant characteristics, (2) optical factors, (3) smoking/drug use, (4) environmental aspects, and (5) breathing gases and partial pressures. We also discuss the application of cFFF measurements in the field of diving and hyperbaric medicine. In addition, we provide recommendations for interpreting changes in the cFFF threshold and how they are reported in research studies.

The theory of critical flicker fusion frequency and its application in cataracts

Background

Due to media opacity, it is usually difficult to accurately evaluate the postoperative visual acuity in cataracts patients. As a small and portable tool, the critical flicker fusion frequency (CFF) device reflects the temporal resolution of visual function and has been widely used in clinical research. However, poor understanding of the technique and equipment limitations have restricted its clinical application in China.

Main text

There was a decrease in the CFF value in various ophthalmic diseases, indicating that the CFF is sensitive to detect visual functional changes. A number of studies have shown that the CFF test can accurately distinguish patients with simple cataracts from those with cataracts combined with fundus disease, and, as a visual test, it can more accurately predict postoperative visual acuity without being affected by media opacity. This study comprehensive reviews the basic principles of CFF and its application in ophthalmology, especially in cataracts.

Conclusions

As one of the tools for dynamic visual function detection, the CFF test could help doctors to assess the possible presence of fundus disease in cataracts patients, especially in eyes with dense cataracts, and more precisely provide a reasonable visual prognosis than other available visual tests.

Usefulness of critical flicker fusion frequency measurement and its laterality for evaluating compressive optic neuropathy due to pituitary neuroendocrine tumors

Critical flicker fusion frequency (CFF) is a short but sensitive method for evaluating optic nerve function. We measured CFF in patients with pituitary neuroendocrine tumors (Pit-NETs) to assess its usefulness. Data from 184 patients with nonfunctioning Pit-NETs, who had been treated with transsphenoidal surgery and had no medical history of eye diseases, was used in this retrospective study. Visual acuity decline (VAD) was defined as > 0.10 reduction in logMAR visual acuity and CFF decline (CFD) was defined as CFF value < 35 Hz. Visual field defect (VFD) was evaluated by automated perimetry on a Humphrey visual field analyzer. Potential associations between abnormal test results and tumor height from the suprasellar were analyzed. Contact between the optic nerve or chiasma and the tumor was present and absent in 161 and 23 patients, respectively. In patients showing contact, the difference in CFF between the left and right eyes was larger (p = 0.0008), and the optimal cutoff value using the receiver operating characteristic curve was 3 Hz. Therefore, ≥ 3 Hz was considered positive for CFF laterality (CFL), the most prevalent condition. Tumor height was lower in patients with CFL positivity compared to those with VAD or VFD (p < 0.01). The prevalence of test abnormalities was the highest for small tumors compared to those of other tests. Changes in CFL permit early detection of Pit-NETs. Our results indicate that CFF laterality can be seen in the early stages of compressive optic neuropathy due to Pit-NET.

The clinical application of critical flicker fusion frequency in demyelinating optic neuritis

Purpose

To investigate the application of critical flicker fusion frequency (CFF) in demyelinating optic neuritis (DON).

Methods

A cross-sectional study. A total of 127 eyes in 69 DON patients and 63 eyes in 33 healthy control (HC) groups were included between January 2021 to September 2021 from Department of Ophthalmology, PLA General Hospital. Patients underwent best-corrected visual acuity (BCVA), visual field, optical coherence tomography (OCT), flash visual evoked potential (F-VEP), and CFF examinations. The affected eyes were divided into aquaporins 4 (AQP4-), myelin oligodendrocyte glycoprotein (MOG-), and double negative DON according to serum antibody; mild, moderate, severe degree visual impairment according to BCVA ≥ 0.5, 0.1-0.5, < 0.1; and 4 groups: < 1, 1 ∼< 3, 3 ∼ < 6 and > 6 months according to time interval from onset to CFF examination. One-way ANOVA was used to perform above subgroup analysis. The correlations between CFF and F-VEP peak time, peak value, BCVA and mean visual filed defect (MD) were analyzed in order via Pearson correlation analysis.

Results

he trichromatic values of red, green, and yellow in DON affected eyes were 21.83 ± 9.03, 23.66 ± 10.21, 24.09 ± 10.77 Hz, respectively, which was significantly reduced compared with the HC group (t = -14.82, -14.22, -14.00; P < 0.001). The subgroup analysis showed no significant difference between different antibody subtypes (P = 0.914 <0.848 <0.604), whereas, a significant decrease of CFF trichromatic value was found in severe visual acuity impairment group (P < 0.001). There was a significant difference in CFF- trichromatic values at different time points (P < 0.001), to be specific, CFF fluctuated under 20Hz within 3 months after onset and tended to be stable around 24-28Hz. Correlation analysis showed that the peak time of F-VEP (r = -0.486, -0.515, -0.526; P < 0.001), BVCA (r = -0.640, -0.659, -0.642; P < 0.001), were negatively correlated with CFF trichromatic values, MD and CFF were positively correlated (r = 0.486, 0.453, 0.476; P = 0.003, 0.006, 0.004).

Conclusions

A significant decrease of CFF value was found in DON-affected eyes, and it has a good correlation with BCVA, MD and latency of F-VEP, and can better reflect the impairment of visual function.

Assessing visual function behind cataract: preoperative predictive value of the Heine Lambda 100 retinometer

PURPOSE

To analyze the accuracy of the Lambda 100 (Heine) potential visual acuity (VA) measurements in subjects undergoing cataract surgery.

METHODS

The medical records of all consecutive patients who underwent clear corneal incision phacoemulsification cataract surgery by a single surgeon between 2010 and 2012 at the Department of Ophthalmology, Hadassah Medical Center, a tertiary care hospital in Jerusalem, Israel, were reviewed. Subjects age 18 or older with a follow-up time of at least 30 days were included. Subjects with previous ocular comorbidities other than glaucoma were excluded. In addition, patients with intraoperative or perioperative complications that could affect final VA were excluded. Analyses were performed to analyze the accuracy of preoperative retinometer potential VA as a predictor of postoperative best-corrected VA.

RESULTS

A total of 374 operated eyes were included. There was a moderate positive correlation between Lambda estimated VA potential and postoperative achieved best-corrected VA (BCVA) (β coefficient 0.35, p<0.0001). Overall Lambda accurately (within 2 Snellen lines) estimated postoperative BCVA results in 60% of cases. The accuracy of prediction was significantly better in moderate cataracts when compared with advanced cataracts (p<0.01) with a twofold tendency towards underestimation in advanced cataracts. A Lambda ≥0.5 decimal has a calculated positive predictive value of 82% and a negative predictive value of 40% for predicting postoperative BCVA outcome ≥0.5 decimal.

CONCLUSIONS

Lambda may be used to relatively accurately predict postoperative BCVA in cataract patients, specifically in those with moderate cataracts.

Posterior segment causes of reduced visual acuity after phacoemulsification in eyes with cataract and obscured fundus view

Purpose

To determine posterior segment causes of reduced visual acuity after phacoemulsification in eyes with cataract and obscured fundus view.

Patients and methods

Retrospective review of medical records of patients with cataract, obscured fundus view, and normal B-scan ultrasonography, undergoing phacoemulsification from May 2005 to March 2012 was conducted. Eyes with fundus pathology, previous trauma, surgery, glaucoma, amblyopia, or uveitic cataract were excluded. Ocular comorbid conditions, preoperative visual acuity (VA), intraoperative and early postoperative complications, and final best corrected visual acuity (BCVA) at 1 month were abstracted from the records.

Results

All 201 eyes of 179 patients studied had a preoperative VA of ≤6/60. Preoperative ocular comorbidity was present in 31 eyes (15.5%). Intraoperative complications occurred in 20 eyes (10%). Postoperative complications developed in 34 eyes (17.0%). One month postoperatively, 175 eyes (87.1%) achieved a BCVA of ≥6/12; whereas 26 eyes (12.9%) achieved a BCVA of ≤6/18. The most common posterior segment causes of reduced VA in the 26 eyes were age-related macular disease in ten eyes (38.5%) and diabetic maculopathy in six eyes (23.1%). Similar fundus pathology was seen preoperatively in the fellow fundus in 10 of the 26 eyes (38.5%).

Conclusion

One month after phacoemulsification in eyes with cataract and obscured fundus view, age-related macular disease and diabetic maculopathy were the most common posterior segment causes of reduced final BCVA. To avoid postsurgical dissatisfaction, patients with obscured fundus view in their preoperative eye should be counseled, especially if posterior segment pathology exists in their fellow eye.

Psychophysics, reliability, and norm values for temporal contrast sensitivity implemented on the two alternative forced choice C-Quant device

The current paper describes the design and population testing of a flicker sensitivity assessment technique corresponding to the psychophysical approach for straylight measurement. The purpose is twofold: to check the subjects' capability to perform the straylight test and as a test for retinal integrity for other purposes. The test was implemented in the Oculus C-Quant straylight meter, using homemade software (MATLAB). The geometry of the visual field lay-out was identical, as was the subjects' 2AFC task. A comparable reliability criterion ("unc") was developed. Outcome measure was logTCS (temporal contrast sensitivity). The population test was performed in science fair settings on about 400 subjects. Moreover, 2 subjects underwent extensive tests to check whether optical defects, mimicked with trial lenses and scatter filters, affected the TCS outcome. Repeated measures standard deviation was 0.11 log units for the reference population. Normal values for logTCS were around 2 (threshold 1%) with some dependence on age (range 6 to 85 years). The test outcome did not change upon a tenfold (optical) deterioration in visual acuity or straylight. The test has adequate precision for checking a subject's capability to perform straylight assessment. The unc reliability criterion ensures sufficient precision, also for assessment of retinal sensitivity loss.

Foveal versus eccentric retinal critical flicker frequency in mild traumatic brain injury

BACKGROUND

The purpose of this study was to assess the critical flicker fusion frequency (CFF) at the fovea and at 10 degrees of horizontal retinal eccentricity and to determine if there was a correlation between CFF and the degree of light and motion sensitivity in individuals with mild traumatic brain injury (TBI).

METHODS

Mean CFF thresholds at the fovea, and 10 degrees to the left and right of the fovea, were obtained in 14 mild TBI and 29 visually normal subjects. A questionnaire was used to quantify the degree of light and motion sensitivity and related factors.

RESULTS

There was no effect of age on CFF under any test condition in either group, nor was there a relation in the TBI group between reported light or motion sensitivity and CFF. Peripheral CFF values were lower in both populations. Among the TBI subjects, there was a trend for lower peripheral CFF values in the periphery and greater mean variability under all 3 test conditions.

CONCLUSIONS

Decreased sensitivity and increased variability in CFF measurements in the TBI population can be attributed to damage to the higher visual pathways.

Clinician versus potential acuity test predictions of visual outcome after cataract surgery

BACKGROUND

The aim of this study was to compare the ability of potential vision tests and clinical judgement to predict postoperative visual acuity after uneventful cataract surgery.

METHODS

Sixty-two subjects (median, 74.5 years) were included in the study. Preoperative measurements included a clinical judgement prediction (based on case history and ocular examination alone), 2 super-illuminated pinhole techniques (distance and near), Potential Acuity Meter and interferometer. Postoperative visual acuity was used as the outcome measure to evaluate the accuracy of the preoperative predictions.

RESULTS

Subjects were categorized as follows: (a) moderate cataract (N = 25); (b) moderate cataract and comorbidity (N = 18), and (c) advanced cataract (N = 19). Preoperative predictions within 2 lines of the postoperative visual acuity were as follows (a, b, and c respectively): clinical judgement (92%, 72%, 58%), super-illuminated pinhole distance (96%, 100%, 21%), super-illuminated pinhole near (92%, 78%, 26%), Potential Acuity Meter (72%, 67%, 21%), and interferometer (56%, 61%, 37%).

CONCLUSIONS

Based on the preoperative predictions above, none of the potential vision tests was useful compared with the clinical judgement in the advanced cataract group. The super-illuminated pinhole (distance) provided additional information beyond clinical judgement in the moderate cataract subgroup. The Potential Acuity Meter and interferometer were inaccurate even in the presence of moderate cataract, and this and other recent findings suggest they should no longer be considered adequate for potential vision assessment.

Critical flicker frequency and related symptoms in mild traumatic brain injury

PRIMARY OBJECTIVE

To determine whether critical flicker frequency (CFF) thresholds are abnormal in individuals with mild traumatic brain injury (TBI) and, if so, if they are correlated with the degree of reported motion and light sensitivity.

METHODS AND PROCEDURES

The foveal CFF threshold was assessed in individuals with mild TBI (n = 18) having varying degrees of reported light and motion sensitivity. Mean CFF values were obtained using the ascending and descending psychophysical method of limits with binocular viewing at 40 cm. A 7-item, rating-scale questionnaire was used to assess the degree of light and motion sensitivity. These parameters were also assessed in a large visually-normal, non-TBI cohort.

MAIN OUTCOMES AND RESULTS

CFF in the mild TBI group was not significantly different across age groups from the visually-normal, non-TBI cohort. However, mean CFF among the mild TBI subjects was significantly higher for the 'light sensitive' and 'motion sensitive' sub-groups when compared to the 'not light sensitive' and 'not motion sensitive' sub-groups. The majority of TBI subjects manifested both light and motion sensitivity.

CONCLUSION

CFF was found to be related to the reported degree of light and motion sensitivity in individuals with mild TBI. Neurological disinhibition as a result of brain injury may be causal of the subjective hypersensitivity to light and motion in the presence of normal CFF.

Comparison of adapted Vryghem macular function test and Lotmar-light interferometer in predicting visual acuity after cataract surgery

PURPOSE

To assess the accuracy of a newly described macular function test (Vryghem macular function test) adapted to our examination equipment and to compare it to the Lotmar-light interferometer for the preoperative evaluation of cataract patients at the University Eye Clinic, Geneva, Switzerland.

METHODS

This prospective study included 71 consecutive patients (72 eyes) who were undergoing uneventful cataract surgery. Testing with the Lotmar-light interferometer and an adapted form of Vryghem macular function test (AVMFT) using a Birkhauser reading chart, a hyperaddition of +8 D and halogen illumination were performed to assess macular function and to predict postoperative visual acuity (VA). The duration of each test and the density and location of lens opacities were also noted. Best-corrected postoperative VA was compared to the predicted values of each test.

RESULTS

The positive predictive value was 94.2% for AVMFT compared to 92.2% for the Lotmar-light interferometer. The negative predictive value was 50% for AVMFT compared to 42.9% for the Lotmar-light interferometer. The sensitivity was 83.1% for AVMFT and 79.7% for the Lotmar-light interferometer. The specificity was 76.9% for AVMFT and 69.2% for the Lotmar-light interferometer. The correlation coefficient for AVMFT and preoperative Lotmar results (both in LogMAR) with postoperative best-corrected VA (poBCVA; LogMAR) were similar (0.74 and 0.77 respectively).

CONCLUSION

The results of this study suggest that AVMFT is as reliable as the Lotmar-light interferometer in predicting postoperative VA after uneventful cataract surgery. The correlation coefficients with postoperative VA were 0.74 and 0.77, respectively. Both tests showed a high positive (94.2% and 92.2%, respectively) but a low negative (50.0% and 42.9%, respectively) predictive value.

Critical flicker fusion test of potential vision

PURPOSE

To continue developing a potential vision test based on the critical flicker fusion (CFF) phenomenon by using a brighter stimulus and optimizing its size.

SETTING

Flinders Eye Centre, Flinders Medical Centre, Flinders University, Bedford Park, South Australia, Australia.

METHODS

In a prospective nonrandomized study, 225 participants were assigned to 1 of 4 groups: normal, media opacity only, retinal/neural disease only, and cataract plus retinal/neural disease. Participants were recruited if they were 20 years or older but were excluded if they had a neurological disorder or medication known to affect CFF. The CFF thresholds were measured for 3 stimulus sizes: 0.5 degree, 1.0 degree, and 1.5 degrees. Discrimination between groups was tested by analysis of variance and receiver operating characteristic analysis. The relationship between visual acuity and CFF in eyes without media opacity was determined by linear regression and used to predict visual outcomes in 23 eyes having cataract surgery.

RESULTS

The mean age of the 225 participants was 71.4 years +/- 13.2 (SD); 134 (59.8%) were women. The normal group had 41 participants, and the other 3 groups had 61 participants each. Critical flicker fusion thresholds were reduced in retinal/neural disease but resistant to image degradation from media opacity. The 1.5-degree stimulus had 88% sensitivity and 90% specificity for discriminating groups. Visual acuity after cataract surgery was accurately predicted within +/-1 line in 43% of eyes, +/-2 lines in 83%, and +/-3 lines in 100%. All eyes with poor visual acuity (>0.50 logMAR) or dense cataract (>4.0 Lens Opacities Classification System III) were predicted within +/-2 lines.

CONCLUSIONS

The CFF phenomenon effectively discriminated between subjects with and without retinal/neural disease and accurately predicted visual outcome after cataract surgery. The use of a brighter stimulus enhanced performance in cases of dense media opacity.

Perceptual learning of motion leads to faster flicker perception

Critical flicker fusion thresholds (CFFT) describe when quick amplitude modulations of a light source become undetectable as the frequency of the modulation increases. The threshold at which CFF occurs has been shown to remain constant under repeated testing. Additionally, CFF thresholds are correlated with various measures of intelligence, and have been regarded by clinicians as a general measure of cortical processing capacity. For these reasons, CFF is used as a cognitive indicator in drug studies, as a measure of fatigue, and has been suggested as a diagnostic measure for various brain diseases. Here we report that CFFT increases dramatically in subjects who are trained with a motion-direction learning procedure. Control tasks demonstrate that CFFT changes are tightly coupled with improvements in discriminating the direction of motion stimuli, and are likely related to plasticity in low-level visual areas that are specialized to process motion signals. This plasticity is long-lasting and is retained for at least one year after training. Combined, these results show that CFFT relates to a specialized sensory process and bring into question that CFFT is a measure of high-level, or general, processes.

Predictions of postoperative visual outcome in subjects with cataract: a preoperative and postoperative study

AIM

To assess the ability of critical flicker frequency (CFF) and optimal reading speed (ORS) to predict the potential vision in patients with cataract with and without ocular comorbidity.

METHODS

The two novel tests were compared with two well established potential vision tests (PVTs), the potential acuity meter (PAM) and the laser interferometer (LI). Measurements were made preoperatively in 1 eye of 88 subjects using the battery of 4 PVTs. Postoperative measurements were made with the CFF and the ORS. The subjects studied were consecutive cases over a 12-month period who fulfilled the inclusion and exclusion criteria, and agreed to participate in this study.

RESULTS

CFF was the PVT most resistant to the presence of cataract. Both CFF and ORS give a similar predictive precision in the presence of cataract and ocular comorbidity, although CFF seems more precise when the cataract is dense.

CONCLUSIONS

The PAM and the LI showed a limited clinical capability in predicting postoperative visual acuity, particularly with dense opacities. The CFF shows the most promise as a PVT, particularly with dense cataract. Further evaluation is required for both CFF and ORS.

Capabilities of potential vision test measurements

PURPOSE

To determine the usefulness of a battery of potential vision tests (PVTs) including potential acuity meter (PAM), laser interferometer (LI), critical flicker/fusion frequency (CFF), superilluminated pinhole at distance (SPH(d)) and near (SPH(n)), and optimal reading speed (ORS) by their independence of the effects of cataracts and sensitivity to macular disease (MD).

SETTING

Department of Optometry, University of Bradford, Bradford and Leeds General Infirmary, Leeds, United Kingdom.

METHODS

Potential vision test measurements were determined in 76 patients with age-related cataract and no other eye disease, 52 patients with MD and clear ocular media, and 28 patients with normal, healthy eyes.

RESULTS

Potential vision tests were independent of the degrading effects of cataract up to a visual acuity (VA) level of 20/200 or worse (CFF), 20/125 (ORS and SPH), and 20/40 (PAM and LI). A high degree of association was found between PVT scores and distance VA in the MD group for SPH(d) (r2 = 0.93), SPH(n) (r2 = 0.89), and PAM (r2 = 0.71). A moderate correlation was found for LI (r2 = 0.55), CFF (r2 = 0.50), and ORS (r2 = 0.45).

CONCLUSIONS

Potential acuity meter and LI showed very limited independence to moderate/dense cataracts and inaccurate predictions in patients with MD. Superilluminated pinhole was relatively unaffected by moderate/dense cataract and yet provided accurate predictions in the presence of MD and clear ocular media. Critical flicker/fusion frequency showed the greatest ability to bypass cataracts, although its ability to predict VA in patients with early MD was limited. The ORS was relatively unaffected by moderate/dense cataract, but its poor ability to predict VA in MD may limit its clinical suitability as a PVT.