Near vision examination in presbyopia patients: Do we need good homologated near vision charts?

BCLA CLEAR Presbyopia: Evaluation and diagnosis

It is important to be able to measure the range of clear focus in clinical practice to advise on presbyopia correction techniques and to optimise the correction power. Both subjective and objective techniques are necessary: subjective techniques (such as patient reported outcome questionnaires and defocus curves) assess the impact of presbyopia on a patient and how the combination of residual objective accommodation and their natural DoF work for them; objective techniques (such as autorefraction, corneal topography and lens imaging) allow the clinician to understand how well a technique is working optically and whether it is the right choice or how adjustments can be made to optimise performance. Techniques to assess visual performance and adverse effects must be carefully conducted to gain a reliable end-point, considering the target size, contrast and illumination. Objective techniques are generally more reliable, can help to explain unexpected subjective results and imaging can be a powerful communication tool with patients. A clear diagnosis, excluding factors such as binocular vision issues or digital eye strain that can also cause similar symptoms, is critical for the patient to understand and adapt to presbyopia. Some corrective options are more permanent, such as implanted inlays / intraocular lenses or laser refractive surgery, so the optics can be trialled with contact lenses in advance (including differences between the eyes) to better communicate with the patient how the optics will work for them so they can make an informed choice.

Toward an internationally accepted standard for reading charts

Patients who suffer from sight-threatening eye diseases share a desire to regain a comfortable reading ability. In light of the modern advances achieved in ophthalmic diagnosis and therapy, and because a significant lack of comparability between reading charts still exists, there is an increasing need for a worldwide standard in the form of a norm for diagnostic reading charts. Already, applied advancements such as digital print, which allow a calibration of the print sizes of reading charts in correctly progressing geometric proportions by using the actual height of a lower case "x" in millimeters (x-height), and psychophysically standardizing reading charts and their test items by applying modern statistical methods have significantly contributed to establishing a norm for reading charts. In 2020, a proposal of the British delegation was accepted by the International Organization for Standardization (ISO) group "Visual Optics and Optical Instruments," and a working group was established. Bearing in mind the efforts of the ISO with regard to an international norm, this review article is intended to (a) give an overview of the historical background and related normative approaches for diagnostic reading tests used in ophthalmology and optometry, (b) explain psychophysical and technical concerns, and (c) discuss the possibilities and limits of concepts that seem relevant to developing a modern standard for reading charts.

Impact of personal protective equipment on the clarity of vision among trachoma survey graders and trichiasis surgeons in the context of COVID-19

BACKGROUND/AIMS

The COVID-19 pandemic necessitated the use of personal protective equipment for those involved in trachoma survey grading and trichiasis surgery. We sought to determine which configuration of a face shield would be less likely to impact grading accuracy and ability to conduct trichiasis surgery. The research also included assessment of comfort, ease of cleaning and robustness.

METHODS

There were three research phases. In phase 1, assessment of four potential face shield configurations was undertaken with principal trachoma graders and trichiasis surgeon trainers to decide which two options should undergo further testing. In phase 2, clarity of vision and comfort (in a classroom environment) of the two configurations were assessed compared with no face shield (control), while grading trachomatous inflammation-follicular (TF). The second phase also included the assessment of impact of the configurations while performing trichiasis surgery using a training model. In phase 3, face shield ease of use was evaluated during routine surgical programmes.

RESULTS

In phase 2, 124 trachoma graders and 28 trichiasis surgeons evaluated the 2 face shield configurations selected in phase 1. TF agreement was high (kappa=0.83 and 0.82) for both configurations compared with not wearing a face shield. Comfort was reported as good by 51% and 32% of graders using the two configurations. Trichiasis skill scores were similar for both configurations.

CONCLUSION

The face shield configuration that includes a cut-out for mounting the 2.5× magnifying loupes does not appear to impact the ability or comfort of trachoma graders or trichiasis surgeons to carry out their work.

Non-Miotic Improvement in Binocular Near Vision with a Topical Compound Formula for Presbyopia Correction

INTRODUCTION

The aim of this case series was to examine the association between unaided binocular visual acuity for near vision and pupil change after the instillation of a special topical formulation for presbyopia treatment.

METHODS

This was a case series consisting of consecutive participants with presbyopia aged 40-70 years who were tested for visual acuity and pupil diameter before and 2 h after instillation of a formulation of pilocarpine and phenylephrine drops (FOV Tears) for presbyopia. Participants underwent subjective refraction, photopic and scotopic pupil diameter measurement and unaided monocular and binocular visual acuity testing by logMAR for distance and near vision both pre- and post-instillation of eye drops.

RESULTS

The study enrolled 363 subjects (n = 176 women, 48%) with a mean (± standard deviation) age of 50.4 ± 5.8 years. Mean spherical equivalent (SE) changed significantly (- 0.17 Diopters) after instillation of the FOV Tears formulation (p < 0.001). Post-instillation of eye drops, the scotopic pupil diameter decreased by 0.97 ± 0.98 mm, and the near visual acuity by logMAR improved significantly by nearly two lines (p < 0.01). In the linear regression analyses, age (p < 0.001) and SE pre-drop instillation (p < 0.001) were associated with unaided binocular visual acuity. The changes in photopic pupil diameter and the scotopic pupil diameter were not associated with unaided binocular visual acuity.

CONCLUSIONS

The use of the pilocarpine and phenylephrine formulation (FOV Tears) improved binocular visual acuity for near vision in presbyopic patients, and the effect was independent of pupil change.

Possible limits of calibrating reading charts with the Landolt ring: a microscopic study

Purpose

To evaluate microscopically whether the print quality and accuracy of sizing of Landolt ring near vision charts are adequate for the calibration of reading charts.

Methods

Near vision charts with Landolt rings from Oculus GmbH (C-Test; Wetzlar, Germany), Precision Vision (Woodstock, IL) and the RADNER Charts were examined, as well as custom-made Landolt rings optimized for print quality. Microscopic investigations and measurements were performed by using a Huvitz HSZ 600 stereomicroscope (Nikon NIS Elements software) to evaluate the height of the Landolt rings, the thickness of the lines, and the width of the openings. The deviations from the mathematically correct values, which were calculated as given in the EN/ISO 8596 and by the International Council of Ophthalmology (ICO), were analyzed (calculated for a test distance of 40 cm).

Results

All the near vision charts showed notable deficiencies in print quality and aberrations from the nominal values in the height, thickness of the lines, and width of the openings. The openings were too narrow, whereas the height and thickness of the lines were larger than the nominal values. Even the openings of Landolt rings optimized for print quality were not always within an acceptable 5% tolerance and need further improvement.

Conclusion

This study reports inaccuracies in the heights, thicknesses of the lines, and widths of the openings of Landolt rings in all the near vision charts investigated. The extent of these inaccuracies excludes such near vision charts as reference tests for the calibration of reading charts. The x-height in relation to the visual angle still seems to be the most reliable method for standardizing the print sizes for reading charts.

Font effects on reading parameters: comparing Radner Reading Charts printed in Helvetica and Times Roman

Purpose

To investigate the effect of font choice on reading parameters by using the RADNER Reading Charts printed in two fonts (Helvetica vs. Times Roman) equalized in terms of x-height.

Methods

This is a cross-sectional study of 40 participants with healthy eyes (18 to 60 years of age; mean: 42.13 ± 12.28 years). Reading performance was evaluated binocularly with RADNER Reading Charts printed in either Helvetica Neue (T1) Roman sans serif (Adobe) or Times New Roman PS Roman serif (Adobe). The test distance was 40 cm. Reading charts were presented in random order. Reading acuity (RA), mean reading speed of all sentences read (MEAN-ALL RS), mean reading speed from 0.8 logRAD to 0.3 logRAD (MEAN-RS), maximum reading speed (MAX-RS), and critical print size (CPS) were compared.

Results

The RA values obtained for the Helvetica and Times Roman fonts (in full logarithmic units of 0.1 logRAD) did not differ between the two fonts (mean for both fonts: − 0.128 ± 0.064 logRAD; 95% CI for both: − 0.148; − 0.107 logRAD). The differences in all other reading parameters between the two fonts were small and not statistically significant. The analyses revealed narrow confidence intervals and good coefficients of reliability. Except for the CPS (r = 0.49) and RA (equal for Helvetica and Times Roman), the correlations for all parameters were high, ranging from r = 0.92 to r = 0.98.

Conclusion

The equivalent reading performance obtained with Helvetica and Times Roman (when equalized in x-height and layout) makes these font types interchangeable as standards for reading charts.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-022-05665-y.

Effectiveness of an mHealth system on access to eye health services in Kenya: a cluster-randomised controlled trial

Background

There is limited access to eye health services in many low-income and middle-income populations. We aimed to assess the effectiveness in increasing service utilisation of the Peek Community Eye Health (Peek CEH) system, a smartphone-based referral system comprising decision support algorithms (Peek Community Screening app), SMS reminders, and real-time reporting.

Methods

In this cluster-randomised controlled trial of eye health in Kenya, community unit clusters were defined as one health centre and its catchment population. Clusters were randomly allocated (1:1) to receive Peek CEH and referral (intervention group) or standard care via periodic health centre-based outreach clinics and onward referral (control group). Individuals in the intervention group were assessed at home by screeners and those referred were asked to present for triage assessment in a central location. They received regular SMS reminders. In both groups, community sensitisation was done followed by a triage clinic at the cluster health centre 4 weeks after sensitisation. During triage, individuals in both groups were assessed and treated and, if necessary, referred to a specific hospital. Individuals in the intervention group received further SMS reminders. The primary outcome was the mean attendance rate (the number of people per 10 000 population) at triage of those with confirmed eye conditions, as assessed at 4 weeks after sensitisation in the intention-to-treat population. We estimated the intervention effect using a Student's t-test on cluster-level rates. This trial is registered with Pan African Clinical Trial Registry, number 201807329096632.

Findings

Between Nov 26, 2018, and June 7, 2019, of the 85 community units in Trans Nzoia County, Kenya, 49 were excluded. We randomly allocated 18 community units each to the intervention group (68 348 individuals) and the control group (60 243 individuals). 9387 individuals from the intervention group and 3070 from the control group attended triage assessment. The mean attendance rate at triage by individuals with eye problems was 1429 (92% CI 1228–1629) in the intervention group and 522 (418–625) in the control group (rate difference 906 per 10 000 [95% CI 689–1124; p<0·0001]).

Interpretation

The Peek CEH system increased primary care attendance by people with eye problems compared with standard approaches, indicating the potential of this mobile health package to increase service uptake and guide appropriate task sharing.

Funding

The Queen Elizabeth Diamond Jubilee Trust and Wellcome Trust.

Smartphone-Guided Algorithms for Use by Community Volunteers to Screen and Refer People With Eye Problems in Trans Nzoia County, Kenya: Development and Validation Study

Background

The provision of eye care services is currently insufficient to meet the requirements of eye care. Many people remain unnecessarily visually impaired or at risk of becoming so because of treatable or preventable eye conditions. A lack of access and awareness of services is, in large part, a key barrier to handle this unmet need.

Objective

This study aimed to assess whether utilizing novel smartphone-based clinical algorithms can task-shift eye screening to community volunteers (CVs) to accurately identify and refer patients to primary eye care services. In particular, we developed the Peek Community Screening app and assessed its validity in making referral decisions for patients with eye problems.

Methods

We developed a smartphone-based clinical algorithm (the Peek Community Screening app) using age, distance vision, near vision, and pain as referral criteria. We then compared CVs’ referral decisions using this app with those made by an experienced ophthalmic clinical officer (OCO), which was the reference standard. The same participants were assessed by a trained CV using the app and by an OCO using standard outreach equipment. The outcome was the proportion of all decisions that were correct when compared with that of the OCO.

Results

The required sensitivity and specificity for the Peek Community Screening app were achieved after seven iterations. In the seventh iteration, the OCO identified referable eye problems in 65.9% (378/574) of the participants. CVs correctly identified 344 of 378 (sensitivity 91.0%; 95% CI 87.7%-93.7%) of the cases and correctly identified 153 of 196 (specificity 78.1%; 95% CI 71.6%-83.6%) cases as not having a referable eye problem. The positive predictive value was 88.9% (95% CI 85.3%-91.8%), and the negative predictive value was 81.8% (95% CI 75.5%-87.1%).

Conclusions

Development of such an algorithm is feasible; however, it requires considerable effort and resources. CVs can accurately use the Peek Community Screening app to identify and refer people with eye problems. An iterative design process is necessary to ensure validity in the local context.

Development and Validation of the Minnesota Low Vision Reading Test (MNRead) Acuity Chart for the Asante Twi Language

Aim

To design and validate a MNREAD Asante Twi version reading chart, to aid in the assessment of near visual acuity of natives Ghanaians.

Methods

Cross-sectional and experimental designs were employed in phases I and II respectively of this study. The chart was developed using 20 transited pupils in class four in the Kumasi metropolis in phase I and validated in a clinical setting at the Manhyia District Hospital, Kumasi, using students in phase II.

Results

A total of 100 participants (mean age; 22.19 ± 1.61 years) were involved in the second phase of this study. A Pearson product-moment correlation coefficient was computed to assess the relationship between MNREAD Asante Twi charts logMAR scores in both eyes. The MNREAD-Asante Twi acuity charts had very strong correlations (r = 0.94, p < 0.001) for MNREAD set 1A (black on white background) scores and MNREAD set 2A (black on white background) for acuity scores. Correlation between MNREAD set 1B (white on black background) scores and MNREAD set 2B (white on black background) scores was r = 0.95, p < 0.001.

Conclusion

MNREAD Asante Twi reading chart will enhance the measurement of near visual function in native Ghanaians.

The Impact of Progressive Visual Field Constriction on Reading Ability in an Inherited Retinal Degeneration

BACKGROUND

The ability to read is an important factor in the quality of life. Choroideremia is an inherited retinal degeneration presenting with gradual, progressive constriction of the central visual field, providing a useful disease model to investigate the impact of the visual field on reading ability.

OBJECTIVE

The aim of this study was to provide practical guidance on the usefulness of measuring reading ability in patients.

METHOD

The Radner Reading Test was administered to 33 patients (65 eyes with choroideremia). To quantify the residual retinal area, the patients underwent microperimetry and imaging. The visual angle subtended by the largest letter read by each subject was calculated using Emsley's Model Eye.

RESULTS

A minimum of 1 letter must be seen to allow the eye to read, with preservation of foveal sensitivity. The relationship between reading speed and acuity varies with the visual field. The reading speed is higher in eyes with an intact fovea (p < 0.001 right eye, p = 0.06 left eye). Qualitative analysis of the direction of the intact retina did not indicate any directional impact on measurements.

CONCLUSIONS

In order to read, an eye must have enough retinal width close to the fovea to see at least 1 full letter. Direction of print does not impact the ability to read, allowing results from different languages to be combined in clinical trials.

Object kinetics perception in auto-stereoscopic vision

In this paper, we study the conditions for the perception of object kinetics, produced by a multiview auto-stereoscopic system and a set of still images. We assess the capabilities and performances of such an optical system to encode complex trajectories and kinetics of objects moving in depth. In particular, we set up rules to create motions with nonuniform velocities, when obtained by motion parallax induced by the observer. We establish a link with plenoptic systems from where we derive applicable scaling rules to ensure stereoscopic vision and to provide fluid motion perception with satisfying visual comfort. Finally, we scale the optical system, thanks to obtained parameters, to emulate the perception of object motions in depth with fluid kinetics and to create impressive motion effects.

Standardization of Reading Charts: A Review of Recent Developments

This review gives an overview of the current status of standardization by statistical evaluation of reading charts. First begun only 20 years ago, the statistical evaluation of reading charts now reflects an increasing clinical and scientific interest in standardized, comparable, and reproducible reading charts.For clinical or research purposes in human subjects, standardization of psychophysical tests and their test items by statistical evaluation is mandatory because it provides experimental control. Initial attempts at reading chart standardization were made by characterizing the test items, either in terms of a selection of unrelated words or in terms of sentences representing a constant number of characters, including spaces. As initiated by the RADNER Reading Charts, standardization of reading charts (and test items) by statistical evaluation has gained increasing clinical and scientific interest in the last two decades and has later also been applied to some of the other modern reading charts. A literature search was performed with respect to reading charts that (a) have been produced in accordance with the recommendations of the International Council of Ophthalmology (geometrical print size progression), (b) have been statistically analyzed, and/or (c) use clearly characterized test items (conceptually and statistically). These reading charts are as follows: the Bailey-Lovie Word Reading Charts, the Colenbrander Cards, the RADNER Reading Charts, the MNREAD Acuity Charts, the Smith-Kettlewell Reading Test (SKread Test), the C-Read Charts, and the Balsam Alabdulkader-Leat (BAL) Chart. The test items of these charts have been characterized either empirically or by statistical analysis and selection. The extent of the statistical evaluation of the reading charts varies. Despite their different methodological approaches, these reading charts represent an advancement that has made possible the useful comparison and reproducible evaluation of near visual performance.

Peek Community Eye Health - mHealth system to increase access and efficiency of eye health services in Trans Nzoia County, Kenya: study protocol for a cluster randomised controlled trial

BACKGROUND

Globally, eye care provision is currently insufficient to meet the requirement for eye care services. Lack of access and awareness are key barriers to specialist services; in addition, specialist services are over-utilised by people with conditions that could be managed in the community or primary care. In combination, these lead to a large unmet need for eye health provision. We have developed a validated smartphone-based screening algorithm (Peek Community Screening App). The application (App) is part of the Peek Community Eye Health system (Peek CEH) that enables Community Volunteers (CV) to make referral decisions about patients with eye problems. It generates referrals, automated short messages service (SMS) notifications to patients or guardians and has a program dashboard for visualising service delivery. We hypothesise that a greater proportion of people with eye problems will be identified using the Peek CEH system and that there will be increased uptake of referrals, compared to those identified and referred using the current community screening approaches.

STUDY DESIGN

A single masked, cluster randomised controlled trial design will be used. The unit of randomisation will be the 'community unit', defined as a dispensary or health centre with its catchment population. The community units will be allocated to receive either the intervention (Peek CEH system) or the current care (periodic health centre-based outreach clinics with onward referral for further treatment). In both arms, a triage clinic will be held at the link health facility four weeks from sensitisation, where attendance will be ascertained. During triage, participants will be assessed and treated and, if necessary, referred onwards to Kitale Eye Unit.

DISCUSSION

We aim to evaluate a M-health system (Peek CEH) geared towards reducing avoidable blindness through early identification and improved adherence to referral for those with eye problems and reducing demand at secondary care for conditions that can be managed effectively at primary care level.

TRIAL REGISTRATION

The Pan African Clinical Trials Registry (PACTR), 201807329096632 . Registered on 8 June 2018.

Age-related changes in baseline reading acuity and speed as measured using RADNER Reading Charts in healthy eyes with best corrected ETDRS distance acuity

PURPOSE

To assess age-related differences in baseline measures of reading performance obtained from the RADNER Reading Charts in healthy eyes with best corrected (ETDRS) distance acuity.

METHODS

Cross-sectional study of participants (n=200) aged 25-74 years (n=20 per 5 years age group). Best corrected distance visual acuity was measured monocularly with ETDRS 2000 Charts. Reading performance was evaluated binocularly with the RADNER Reading Charts. Reading acuity (RA), reading acuity score (RA score), mean reading speed (MEAN-RS), maximum reading speed, reading speed with a long paragraph, critical print size (CPS) and the logMAR/logRAD ratio were analysed.

RESULTS

RA, RA score, CPS-1 (last logRAD with normal reading speed) and ETDRS acuity did not change significantly between age 25 and 54 years. Overall, the mean RA was -0.091±0.07 logRAD, and the RA score was -0.069±0.07 logRAD. The mean difference between the RA and best ETDRS acuity was 0.0603±0.055 logMAR (r=0.62; p<0.05). The logMAR/logRAD ratio was 87.75%±11.23%. The MEAN-RS ranged from 189±21.9 words per minute (wpm) for the group aged 70-74 years to 236±22.5 wpm for the group aged 40-44 years and correlated well with the long paragraph results (r=0.87).

CONCLUSION

Best corrected RA, reading speed and ETDRS distance acuity were constant until the age of 54 years. An age-related break point was found between the groups aged 50-54 years and 55-59 years; for reading speed, the break point can be assumed to be within the age range of 50-54 years.

Comparative analysis of visual outcomes, reading skills, contrast sensitivity, and patient satisfaction with two models of trifocal diffractive intraocular lenses and an extended range of vision intraocular lens

PURPOSE

To compare visual and contrast sensitivity (CS) outcomes, reading skills, and spectacle independence in patients implanted with two models of trifocal intraocular lenses (IOLs) or an extended range of vision (ERV) IOL.

METHODS

This non-randomized prospective series of cases included 120 eyes of 60 patients undergoing cataract surgery with bilateral implantation of three different IOLs: the ERV IOL Tecnis Symfony (40 eyes) (Abbott Medical Optics), the trifocal IOLs PanOptix IQ (40 eyes) (Alcon), and AT LISA tri 839MP (40 eyes) (Carl Zeiss Meditec). Visual results, photopic and mesopic CS, binocular reading skills (MNREAD charts), and patient satisfaction were evaluated 3 months after surgery.

RESULTS

There was no statistically significant difference between groups regarding uncorrected and corrected distance visual acuity. The Tecnis Symfony IOL showed better mesopic intermediate visual outcomes than the two trifocal IOLs (p < 0.05 vs AT LISA). Under photopic conditions, AT LISA tri 839MP and PanOptix IQ showed better near visual outcomes compared with the ERV IOL (p < 0.05 to p < 0.001). The Tecnis Symfony IOL provided significantly better photopic and mesopic CS outcomes than the other IOL models (p < 0.001). Reading skills were not significantly different between the three IOL models (p > 0.05). Less patients implanted with the two trifocal IOLs required a near addition than patients with the ERV IOL.

CONCLUSIONS

All the tested IOLs provided good visual outcome, reading performance, and spectacle independence after cataract surgery. While trifocal IOLs gave better near visual acuity results, the ERV IOL provided better contrast sensitivity.

Visual performance, reading ability and patient satisfaction after implantation of a diffractive trifocal intraocular lens

Purpose

To evaluate visual outcome, reading performance, contrast sensitivity, and patient satisfaction after cataract surgery with implantation of a diffractive trifocal intraocular lens (IOL).

Patients and methods

A total of 42 eyes (21 patients) underwent cataract surgery with implantation of the trifocal IOL AT LISA tri 839MP. Visual acuity, contrast sensitivity, and patient satisfaction were evaluated 3 months postoperatively. Reading performance was evaluated at 3 months postoperatively with the MNREAD charts.

Results

All eyes achieved a 3-month postoperative monocular uncorrected distance visual acuity of 0.10 logMAR or better (Snellen 20/25). Likewise, 97.62% and 85.71% of eyes achieved a postoperative monocular uncorrected intermediate, and near visual acuity of 0.20 logMAR (Snellen 20/30) or better. All patients achieved postoperative binocular uncorrected distance visual acuity, uncorrected intermediate, and uncorrected near visual acuity of 0.20 logMAR (Snellen 20/30) or better. Mean photopic reading acuity and speed were 0.24±0.07 logMAR and 177.61±20.67 words per minute, respectively. Postoperative contrast sensitivity values were within the ranges of normality for all spatial frequencies evaluated. Postoperative spectacle independence and patient satisfaction was very high, with most of the patients reporting a good or very good visual quality at far, intermediate, and near distances. All patients would choose the same lens again.

Conclusion

The evaluated trifocal IOL provides an effective restoration of the visual function after cataract surgery, with high levels of distance, intermediate, and near visual acuity, strong reading performance, and patient satisfaction.