Visual Acuity Variability: Comparing Discrepancies between Snellen and ETDRS Measurements among Subjects Entering Prospective Trials

Visual Function Measurements in Eyes With Diabetic Retinopathy: An Expert Opinion on Available Measures

Clinical Relevance

Visual function impairment from diabetic retinopathy can have a considerable impact on patient's quality of life. Best-corrected visual acuity (BCVA) is most commonly used to assess visual function and guide clinical trials. However, BCVA is affected late in the disease process, is not affected in early disease, and does not capture some of the visual disturbances described by patients with diabetes. The goal of this report is to evaluate the relationship between diabetic retinal disease (DRD) and visual function parameters to determine which if any of them may be used in a future DRD staging system.

Methods

The visual functions working group was 1 of 6 areas of DRD studied as part of the DRD staging system update, a project of the Mary Tyler Moore Vision Initiative. The working group identified 12 variables of possible interest, 7 of which were judged to have sufficient preliminary data to suggest an association with DR to warrant further review: microperimetry, static automated perimetry, electroretinogram (ERG) oscillatory potentials, flicker ERG, low luminance visual acuity (LLVA), contrast sensitivity (CS), and BCVA. The objective field analyzer (OFA) was added after subsequent in-person workshops.

Results

Currently, the only visual function test available for immediate use is BCVA; the remaining tests are either promising (within 5 years) or have potential (>5 years) use. Besides BCVA, most visual function tests had a limited role in current clinical care; however, LLVA, CS, flicker ERG, and OFA demonstrated potential for screening and research purposes.

Conclusions

Although current visual function tests are promising, future prospective studies involving patients with early and more advanced retinopathy are necessary to determine if these tests can be used clinically or as endpoints for clinical studies.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Magnitude of Visual Acuity Change with ETDRS versus Snellen Testing in Clinical Trials: Implications for Clinic-Based Outcomes

Purpose

To compare visual acuity (VA) changes using standardized ETDRS best-corrected visual acuity (BCVA) and nonstandardized Snellen VA among subjects enrolled in clinical trials.

Design

Retrospective study.

Participants

Patients enrolled in prospective clinical trials at 3 urban retina practices.

Methods

Best available Snellen VA at the clinic visit before study entry and after exit were compared with the ETDRS BCVA at trial entry and exit. The correlation and discrepancies between Snellen VA and ETDRS methods as well as the VA changes from trial entry to exit were evaluated.

Main Outcome Measures

The discrepancy between VA change from trial entry to exit using Snellen VA versus ETDRS BCVA methods.

Results

A total of 273 eyes were included. The mean (standard deviation [SD]) Snellen VA was 58.1 (20) ETDRS-equivalent letters (Snellen 20/69) at the clinic visit before trial entry and 61.6 (21) ETDRS-equivalent letters (Snellen 20/59) at the visit after trial exit. The mean (SD) ETDRS BCVA was 65.5 (16) letters (Snellen 20/49) at trial entry and 70.5 (17) letters (Snellen 20/39) at trial exit. The mean VA change from trial entry to exit was not significantly different for ETDRS (5 letters of vision gain) compared with Snellen (3.6 letters of vision gain) methods (P = 0.061). Eyes with baseline Snellen VA 20/50 or worse gained significantly more letters using Snellen (9.3 ± 22.3 letters) compared with ETDRS (5.2 ± 18.7 letters; P = 0.012). Among eyes with baseline Snellen VA of > 20/50, VA gain was significantly greater with the ETDRS method (4.9 ± 12.3 letters) compared with Snellen (-1.5 ± 12.3 letters; P < 0.001).

Conclusions

The mean VA change from clinical trial entry to exit was similar between the ETDRS and Snellen methods. However, among patients with worse baseline Snellen vision, the magnitude of VA change was greater with Snellen compared with ETDRS, whereas among those with better baseline vision, this magnitude was greater with the ETDRS method. Understanding the proportion of the study population with varying VA levels may have implications for interpreting VA outcomes from retrospective clinic-based studies compared with those reported in clinical trials.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Diurnal Variation of Visual Acuity and Refraction in Fuchs Endothelial Corneal Dystrophy

PURPOSE

Patients with advanced Fuchs endothelial corneal dystrophy frequently report poor vision in the morning, which improves as the day progresses. This study quantified the amount of variation in near and distance visual acuity and refraction over the course of a day.

METHODS

This was a prospective cohort study. Best-corrected distance visual acuity and near visual acuity were tested in participants with clinically advanced Fuchs dystrophy and in controls with healthy corneas. Subjective refraction and autorefraction were conducted in a presumed steady state in the afternoon. Measurements were repeated directly after eye opening in the hospital the next morning. In a subgroup, measurements were repeated every 30 minutes for up to 2 hours.

RESULTS

In Fuchs dystrophy, the mean distance visual acuity was worse by -3 letters (95% confidence interval, -4 to -1) directly after eye opening in the morning compared with late afternoon. No such difference was seen in healthy corneas. In Fuchs dystrophy, visual acuity improved over the course of the study. Visual acuity in the morning could be improved with fine tuning of refraction, and refractive changes were exclusive to Fuchs dystrophy (0.5-1.0 D in spherical equivalent in 30%, >1.0 D in 2% of eyes).

CONCLUSIONS

Distance and near visual acuity and refraction changes over the course of the day in patients with advanced Fuchs dystrophy. Although small changes in refraction may not usually require a second set of glasses for the first hours of the day, diurnal variation should be considered when determining disease severity in routine practice and in clinical trials.

Visual Acuity Examination Methodology in Keratoconus

Visual acuity is one of the most important parameters for evaluating the vision of patients with keratoconus. This study reviewed 295 articles related to keratoconus published between 2017 and 2022 in which visual acuity was one of the parameters measured. The methodology of visual acuity testing in studies on keratoconus was thoroughly analyzed. The analysis showed that the most commonly indicated chart for testing visual acuity papers on keratoconus is the Snellen chart. It was shown that in 150 out of 295 articles, the authors do not describe the methodology for testing visual acuity. What is more, it was also shown that in 68 of the 295 articles which were analyzed, a procedure for converting visual acuity tested with a Snellen chart into a logMAR scale was used. In this review, we discuss the validity and reliability of such conversions. In particular, we show that insufficient description of visual acuity testing methodology and lack of information on the conversion of visual acuity results into the logMAR scale may contribute to the misinterpretation of visual acuity test results.

TREYESCAN: configuration of an eye tracking test for the measurement of compensatory eye movements in patients with visual field defects

The Traffic Eye Scanning and Compensation Analyzer (TREYESCAN) is introduced as an innovative eye tracking test designed to measure compensatory eye movements in individuals with visual field defects. The primary objective of the test is to quantitatively assess and analyze the compensatory eye movements employed by patients with visual field defects while viewing videos of various traffic scenes from the viewpoint of a driver of a passenger car. The filming process involved capturing a wide range of driving conditions and hazards, aiming to replicate real-world scenarios. Specific dynamic areas of interest within these scenes were selected and assessed by a panel of experts on medical and practical fitness to drive. Pilot measurements were conducted on a sample of 20 normally-sighted individuals during two different measurement sessions. The results provide valuable insights into how individuals without visual impairment view the dynamic scenes presented in the test. Moving forward, the TREYESCAN will be used in a case-control study involving glaucoma patients and control subjects, with the goal of further investigating and understanding the mechanisms employed by individuals with glaucoma to compensate for their visual field defects.

Risk Factors for the Development of Fellow Eye Horseshoe Retinal Tears Following Horseshoe Retinal Tear in the Presenting Eye

BACKGROUND

This study investigated factors associated with fellow eye horseshoe retinal tear (HST) development in consecutive patients with a presenting eye HST.

MATERIALS AND METHODS

Medical records were reviewed for patients with initial HSTs between 2015 and 2017 and 24 factors were analyzed. Logistic regression was used to assess factors associated with fellow eye HST development.

RESULTS

In total, 242 patients with an HST were identified with mean follow-up of 68.3 months. Four associations with fellow eye HST development were identified: (1) presence of fellow eye lattice degeneration, (2) subsequent presenting eye HSTs, (3) fellow eye vitreous hemorrhage at presenting eye HST occurrence, (4) OCT-determined stage 3 fellow eye posterior vitreous detachment at presenting eye HST occurrence.

CONCLUSION

Four clinical findings associated with fellow eye HST development following presenting eye HST were identified. These factors may be important considerations during management patients with HST. [Ophthalmic Surg Lasers Imaging Retina 2023;54:338-345.].

Relevance of Visual Acuity Measurement for Therapeutic Decisions in Diabetic Macular Edema

This study aimed to determine the validity of basing retreatment decisions on anatomical criteria alone (captured using optical coherence tomography (OCT)-OCT-guided strategy) rather than the gold standard (combined visual acuity (VA) and OCT) in patients with diabetic macular edema (DME). This cross-sectional study included 81 eyes undergoing treatment for DME from September 2021 to December 2021. An initial therapeutic treatment decision based on OCT results was made on inclusion. Subsequently, in light of the patient's VA score, this initial decision was upheld or adjusted, and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. In 67 out of the 81 eyes included in the study (82.7%), the OCT-guided strategy produced equivalent results to the gold standard. In this study, the OCT-guided retreatment decision strategy yielded sensitivity and specificity of 92.3% and 73.8%, respectively, and PPV and NPV of 76.6% and 91.2%, respectively. These findings differed according to the patient's treatment regimen: the sensitivity and specificity for eyes under a treat and extend regimen was higher, 100% and 88.9%, respectively, than eyes under a Pro Re Nata regimen, 90% and 69.7%, respectively. These findings show that VA testing could be omitted from the follow-up of certain patients with DME treated with intravitreal injections without impacting the quality of care.

Comparison of Snellen Visual Acuity Measurements in Retinal Clinical Practice to Electronic ETDRS Protocol Visual Acuity Assessment

PURPOSE

Evaluate the differences between clinical visual acuity (VA) as recorded in medical records and electronic Early Treatment Diabetic Retinopathy Study (eETDRS) protocol VA measurements and factors affecting the size of the differences.

DESIGN

Retrospective chart review.

PARTICIPANTS

Study and fellow eyes of participants enrolled in DRCR Retina Network Protocols AC and AE (diabetic macular edema), and W (nonproliferative diabetic retinopathy) with clinical VA recorded within 3 months before the protocol visit.

METHODS

Differences and their association with patient and ocular factors were evaluated using linear mixed models with random effects for correlations within sites and participants.

MAIN OUTCOME MEASURE

Difference between VA letter scores measured by eETDRS during a study visit versus measured by Snellen during a regular clinical visit (Snellen fraction converted to eETDRS).

RESULTS

Data from 1016 eyes (511 participants) across 74 sites were analyzed. The mean VA measurements were 68.6 letters (Snellen equivalent 20/50) at the clinical visit and 76.3 letters (Snellen equivalent 20/32) at the protocol visit, with a mean (standard deviation [SD]) of 26 (21) days between visits. Mean (SD) protocol VA was better than clinical VA by 7.6 (9.6) letters overall, 10.7 (12.6) letters in eyes with clinical VA ≤ 20/50 (n = 376), and 5.8 (6.6) letters in eyes with clinical VA ≥ 20/40 (n = 640). On average, the difference between clinical and protocol VA was 1.3 letters smaller for every 1-line (5 letters) increase in clinical VA (P < 0.001). Mean (SD) differences by clinical correction of refractive error were 3.9 (9.0) letters with refraction, 6.9 (9.2) letters with glasses/contact lenses, 7.9 (11.5) letters with pinhole, and 9.8 (9.3) letters without correction (P = 0.06).

CONCLUSIONS

On average, clinical Snellen VA is 1 to 2 lines worse than eETDRS protocol refraction and VA testing, which may partly explain why clinical practice does not always replicate clinical trial results. Eyes with lower clinical measurements and eyes tested without clinical refraction tended to have larger differences. Considering the potential discrepancies between clinical and protocol VA measurements, refracting eyes in the clinic may benefit patients when determining treatment plans and study referrals based on vision.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

USE OF OPTICAL COHERENCE TOMOGRAPHY IN DETECTING RETINAL TEARS IN ACUTE, SYMPTOMATIC POSTERIOR VITREOUS DETACHMENT

PURPOSE

To evaluate the association of posterior vitreous opacities (PVOs) on optical coherence tomography with retinal tears identified on examination in patients with acute, symptomatic posterior vitreous detachment (PVD).

METHODS

Data were retrospectively collected from the medical records of 388 patients with acute, symptomatic PVD between January 1, 2021, and June 30, 2021. Included patients had received a primary diagnosis of PVD and presented with flashes and/or floaters. Optical coherence tomography scans were reviewed by two separate readers for the presence of PVOs. The primary outcome was the presence of retinal tear on fundus photograph and on examination.

RESULTS

Of 388 patients who presented with acute PVD symptoms, 90 (23.2%) were found to have a retinal tear on dilated fundus examination. Among these patients, 78 (86.7%) were found to have PVOs on optical coherence tomography. Statistical analysis demonstrated a significant relationship between the presence of PVOs and retinal tear ( P < 0.01). The sensitivity and specificity of this finding was 86.7% and 72.5%, respectively. Further analysis included area under the curve from receiver operating characteristic curve which was found to be 0.80.

CONCLUSION

The presence of PVOs on optical coherence tomography is suggestive of a retinal tear in patients with acute, symptomatic PVD.

Intense pulsed-light treatment improves objective optical quality in patients with meibomian gland dysfunction

BACKGROUND

To evaluate changes in objective optical quality following intense pulsed light (IPL) treatment combined with meibomian gland (MG) expression (MGX) in patients with MG dysfunction (MGD).

METHODS

This retrospective cross-sectional study included MGD-related dry eye disease (DED) patients who received IPL treatment between March and December 2021 at Kim's Eye Hospital, Seoul, Republic of Korea. Each patient underwent four sessions of IPL treatment using Lumenis M22 (Lumenis Ltd., Yokneam, Israel) and MGX at three-week intervals.

RESULTS

This study included 90 eyes from 45 patients with MGD. The mean age was 52.3 ± 16.1 years (range, 20-75 years), and 53.3% (24/45) of patients were female. Compared with the baseline, all clinical symptoms and signs significantly improved after IPL treatment combined with MGX. All optical quality parameters obtained with an optical quality analysis system (OQAS: Visiometrics, Castelldefels, Spain) have improved significantly over the baseline (p < 0.001).

CONCLUSIONS

In patients with MGD, IPL treatment combined with MGX improved the objective optical quality and clinical signs and symptoms of DED.

Age-related normal limits for spatial vision

PURPOSE

To establish age-related, normal limits of monocular and binocular spatial vision under photopic and mesopic conditions.

METHODS

Photopic and mesopic visual acuity (VA) and contrast thresholds (CTs) were measured with both positive and negative contrast optotypes under binocular and monocular viewing conditions using the Acuity-Plus (AP) test. The experiments were carried out on participants (age range from 10 to 86 years), who met pre-established, normal sight criteria. Mean and ± 2.5σ limits were calculated within each 5-year subgroup. A biologically meaningful model was then fitted to predict mean values and upper and lower threshold limits for VA and CT as a function of age. The best-fit model parameters describe normal aging of spatial vision for each of the 16 experimental conditions investigated.

RESULTS

Out of the 382 participants recruited for this study, 285 participants passed the selection criteria for normal aging. Log transforms were applied to ensure approximate normal distributions. Outliers were also removed for each of the 16 stimulus conditions investigated based on the ±2.5σ limit criterion. VA, CTs and the overall variability were found to be age-invariant up to ~50 years in the photopic condition. A lower, age-invariant limit of ~30 years was more appropriate for the mesopic range with a gradual, but accelerating increase in both mean thresholds and intersubject variability above this age. Binocular thresholds were smaller and much less variable when compared to the thresholds measured in either eye. Results with negative contrast optotypes were significantly better than the corresponding results measured with positive contrast (p < 0.004).

CONCLUSIONS

This project has established the expected age limits of spatial vision for monocular and binocular viewing under photopic and high mesopic lighting with both positive and negative contrast optotypes using a single test, which can be implemented either in the clinic or in an occupational setting.

A Real-World, Multicenter, 6-Month Prospective Study in Greece of the Effectiveness and Safety of Ranibizumab in Patients with Age-Related Macular Degeneration Who Have Inadequately Responded to Aflibercept: The “ELEVATE” Study

Purpose

Real-world evidence on short-term outcomes of ranibizumab in wet age-related macular degeneration (wAMD) following inadequate response to aflibercept is scarce. This study aimed to evaluate the functional and anatomic effects of switching to ranibizumab in cases of wAMD previously treated with aflibercept with inadequate response.

Patients and Methods

Prospective, observational study performed in eight ophthalmology hospital/private clinics in Greece, enrolling consented patients with active wAMD, ≥50 years-old, who had initiated ranibizumab ≥28 days and <2 months after their last aflibercept injection. Data were collected at enrollment, and at 1, 3 and 6 months post-treatment onset (post-baseline).

Results

Between September-2015 and November-2017, 103 eligible patients (56.3% females; mean age: 74.8±8.6 years) were consecutively enrolled. The age at AMD diagnosis in the study eye was 71.3±8.8 years. Aflibercept (median of 5 injections received over 11.3 months) had been discontinued for anatomical (in 69.9%) and/or functional (38.8%) reasons. At baseline (median: 24.3 months after wAMD diagnosis), choroidal neovascularization was occult in 69.1% of evaluable study eyes; 60.2% of the study eyes had pigment epithelial detachment (PED); 42.7% cysts; 21.4% fibrosis; 66.0% subretinal, and 59.2% intraretinal fluid. At 6 months post-baseline: a median of 3 ranibizumab injections (range: 1–6) had been received; the best-corrected visual acuity (BCVA)≥0 letter gain rate was 81.8%; the BCVA ≥15 letter gain rate was 17.0%; BCVA gain was 3.2 letters [mean increase: 3.2±10.0 letters; median: 0.0; p = 0.002]; PED greatest basal diameter (GBD; median: 1470.5 μm) also decreased (median decrease: 114.0 μm; p = 0.019). Baseline central retinal thickness (CRT; median: 312.0 μm) remained unchanged. One patient permanently discontinued ranibizumab due to adverse event occurrence, assessed as not causally related to ranibizumab. There were no ranibizumab-related adverse reactions.

Conclusion

Six-month treatment with ranibizumab in aflibercept inadequate responders led to visual acuity and PED GBD improvements, with no statistically significant CRT change.

Minimum Detectable Change of Visual Acuity Measurements Using ETDRS Charts (Early Treatment Diabetic Retinopathy Study)

In our work, we determined the value of visual acuity (VA) with ETDRS charts (Early Treatment Diabetic Retinopathy Study). The purpose of the study was to determine the measurement reliabilities, calculating the correlation coefficient interclass (ICC), the value of the error associated with the measure (SEM), and the minimal detectable change (MDC). Forty healthy subjects took part. The mean age was 23.5 ± 3.1 (19 to 26) years. Visual acuities were measured with ETDRS charts (96% ETDRS chart nº 2140) and (10% SLOAN Contrast Eye Test chart nº 2153). The measurements were made (at 4 m) under four conditions: Firstly, photopic conditions with high contrast (HC) and low contrast (LC) and after 15 min of visual rest, mesopic conditions with high and low contrast. Under photopic conditions and high contrast, the ICC = 0.866 and decreased to 0.580 when the luminosity and contrast decreased. The % MDC in the four conditions was always less than 10%. It was minor under photopic conditions and HC (5.83) and maximum in mesopic conditions and LC (9.70). Our results conclude a high reliability of the ETDRS test, which is higher in photopic and high contrast conditions and lower when the luminosity and contrast decreases.

Measuring the Contrast Sensitivity Function in Non-Neovascular and Neovascular Age-Related Macular Degeneration: The Quantitative Contrast Sensitivity Function Test

Age-related macular degeneration (AMD) affects various aspects of visual function compromising patients' functional vision and quality of life. Compared to visual acuity, contrast sensitivity correlates better with vision-related quality of life and subjectively perceived visual impairment. It may also be affected earlier in the course of AMD than visual acuity. However, lengthy testing times, coarse sampling and resolution, and poor test-retest reliability of the existing contrast testing methods have limited its widespread adoption into routine clinical practice. Using active learning principles, the qCSF can efficiently measure contrast sensitivity across multiple spatial frequencies with both high sensitivity in detecting subtle changes in visual function and robust test-retest reliability, emerging as a promising visual function endpoint in AMD both in clinical practice and future clinical trials.

Perceptual learning improves visual functions in patients with albinistic bilateral amblyopia: A pilot study

BACKGROUND

Several visual functions are impaired in patients with oculocutaneous albinism (OCA) associated to albinistic bilateral amblyopia (ABA).

OBJECTIVE

In this study, we aimed at exploring whether perceptual learning (PL) can improve visual functions in albinism.

METHOD

Six patients and six normal sighted controls, were trained in a contrast detection task with lateral masking. Participants were asked to choose which of the two intervals contained a foveally presented low-contrast Gabor patch. Targets were presented between higher contrast collinear flankers with equal spatial frequency. When increasing target-to-flanker distance, lateral interactions effect normally switches from inhibition to facilitation, up to no effect.

RESULTS

Our findings showed that before PL, only controls showed facilitation. After PL, results suggest that facilitatory lateral interactions are found both in controls as well as in albino patients. These results suggest that PL could induce higher processing efficiency at early cortical level. Moreover, PL positive effect seems to transfer to higher-level visual functions, but results were not very consistent among tasks (visual acuity, contrast sensitivity function, hyperacuity and foveal crowding).

CONCLUSIONS

Although a small sample size was tested, our findings suggest a rehabilitative potential of PL in improving visual functions in albinism.