Near or distance vision impairment is affecting more and more patients each year and the prevalence is about 2.2 billion people around the world. It has been estimated that in almost half of the cases, the vision impairment has not yet been addressed or could have been prevented. The most important causes of vision impairment are:
* Age-related macular degeneration (AMD),
* Cataract,
* Diabetic retinopathy,
* Glaucoma,
* Uncorrected refracted errors. Among the strategies setup to address vision impairment, preventive care and follow-up treatment and recurrent vision monitoring are the most performant. Standard clinical care requiring patient to physically attend can be a burden for an effective care.
Remote monitoring of visual acuity and follow-up of patients suffering from visual impairment using home-based solutions have known a great outbreak in the las few years. The use of smartphones and tablets supporting applications developed to monitor and evaluate patient's vision has considerably evolved. Moreover, the recent COVID-19 pandemic underlined the need to develop qualified remote care systems to enhance healthcare access.
In the last decade, several tools were developed in the field of ophthalmology for visual function self assessment. The Visual Acuity (VA) testing is the most performed ophthalmologic examination to evaluate patient's potential visual impairment and can be tested either classically with letters optotype charts and projection systems or more recently with the help of digital tools. These tools allow patients to evaluate their VA using applications designed for smartphones, tablets, or computers.
In the standard clinical practice, the VA testing is mostly performed using a Snellen chart (black letters and optotypes of different sizes printed on a white chart), developed in 1862. This tool has been progressively improved, notably with the development of ETDRS charts, considered more accurate and that are thus used in research. These tools required the patient to physically attend the clinical examination, which is sometimes difficult to achieve considering patient mobility issues (age, disability, lack of transportation…), the lack of clinical practices in some areas, or other reasons.
Digital VA testing tools are an interesting alternative to the standard tests performed in clinic.
Nevertheless, their development implies a clinical validation research and certification, to be used for patient ophthalmic care.
Several studies have proved the reliability of digital systems for VA measurement, in remotely operated systems. In 2012, the equivalence of VA measurement using a computer-based logarithmic (logMAR) chart with the standard examination in the physical presence of an optometrist was shown. There was no statistically significant difference between the median VA measurement assessed by the two methods (physical optometrist or remote computer-based system).
The feasibility and the accuracy of a smartphone-based method for VA testing has been addressed in 2014, in the context of Early Treatment for Diabetic Retinopathy Study (ETDRS) testing, using the SightBookTM application. The results of the study evidenced test-retest high reliability and concordance with EDTRS distance VA testing and standard near vision testing.
More recently, VA testing methods have been compared using standard ETDRS chart, near chart and a smartphone-based eye chart application. The study concludes in favour of an equivalent efficiency of the three methods, suggesting a potential interest for remote VA-testing especially when standard clinical examination is not possible or difficult.
Another study, evaluating a smartphone-based VA testing (logMAR) reliability for test-retest compared to standard care showed promising results for remote healthcare and accessibility.
Interestingly, remote VA testing has been shown to be efficient in both adults and children.
The COVID-19 pandemic challenged standard ophthalmologic practice and revealed an acute need of remote healthcare access that emphasizes the development of more efficient tools for VA monitoring and clinical visit scheduling when required.
OdySight® is a medical application intended for patients 18 years of age and older for self-evaluation of visual parameters: near visual acuity and symptoms such as metamorphopsia and scotoma. The test results are sent to the doctor.
OdySight® does not provide any interpretation of the test results and is not intended to provide a diagnosis. OdySight® helps patients to determine whether they need to consult a doctor for diagnosis and treatment.
Three clinical studies have been conducted to evaluate the Odysight® application efficiency compared to standard ophthalmologic care.
In 2019, a prospective, open-labelled, single-arm, single-site study has been performed to compare the results of gold standard VA testing (Sloan ETDRS letter chart for near and distance vision testing), contrast sensitivity (Pelli-Robson chart), and metamorphopsia/scotoma (Amster Grid). The analysis showed a concordance between the results obtained with the OdySight® VA module and the Sloan ETDRS (near and distance). No significant difference has been shown between the OdySight® Amsler Grid module and standard metamorphopsia/scotoma testing. On the other hand, a broader disagreement has been pointed out for the evaluation of contrast sensitivity between the standard Pelli-Robson test and the OdySight® module, which would require more investigation.
The overall results are in favour of using the OdySight® application for remote monitoring of vision between clinic visits and potential assistance for follow-up scheduling.
In 2021, the implementation and clinical efficacy of the OdySight® application was evaluated in a study involving patients (n=60) with oedematous maculopathies receiving standard care. Patients were offered to use OdySight® to self-evaluate changes in their VA. The use of the application and the processing of notifications for VA decrease by the clinical team was analysed for one year to assess the feasibility and the reliability of the system. In all, about 60% of the patients completed at least one test following the prescription and almost 25% of the patients were still using the application after one month. During this trial, 19 notifications for VA decrease were processed by the clinical team in an average of less than 6 days. The decrease in VA was detected with a sensitivity of 92% and a specificity of 99%.
An observational, retrospective, multicentric study, published in 2022, was conducted to evaluate the additional value of using the OdySight® application in addition to a standard follow-up for the detection of exudatives recurrences in patients suffering from macular oedema. In all, 123 patients (149 eyes) were included in the study. The sensitivity of the alerts for the detection of recurrences was around 30%, and the specificity reached 84%. In total, 12 alerts on 39 detected a recurrence and 8 of them resulted in rescheduling or advancement of intravitreal injection. Although the sensitivity and the specificity appear to be a bit low, exudatives recurrences not being necessarily associated to a decrease in VA, the results of the study confirm that OdySight® use can be of interest in the detection of recurrence in advance and allow an anticipated readjustment of the treatment in addition with a standard care follow-up.
