Refractive errors remain one of the leading causes of blindness worldwide, either because of high refractive error itself or because visual problems are left uncorrected.(¹) Presbyopia, an irreversible reduction in the accommodative capacity of the crystalline lens that leads to difficulty focusing on near objects, is among the most common refractive errors.(²) Accommodation, the process that allows clear vision at near, depends on contraction of the ciliary muscle, convergence of the eyes, and pupillary miosis. Together, these actions allow the crystalline lens to become more spherical and ensure that light rays are focused on the retinal plane.(^3,4) Therefore, presbyopia is a condition intrinsically related to aging and may also occur after surgical removal of the lens. A 2018 study estimated that, by 2050, about 20% of the global population will have presbyopia associated with senility.(⁵)

A decrease in near visual acuity is usually the first sign of presbyopia, and the safest and least invasive treatment continues to be prescription glasses, whether monofocal, bifocal or progressive.(⁶) As technologies related to health continue to advance, alternative approaches that complement standard treatment may offer additional benefits and improve visual satisfaction and quality of life.

This study aimed to develop and validate a smartphone application capable of magnifying near images and, through educational videos, informing users about presbyopia. Within this population, we aimed to develop a smartphone application that provides optical support in addition to conventional treatments for presbyopia and to assess patient and user acceptance of this tool, while also promoting understanding of the condition.

This study was approved by the Institutional Review Board (CAAE: 47544221.4.0000.5049) in accordance with Resolution 466/12 of the National Health Council, and all participants provided written informed consent.

This was a prospective, cross-sectional quantitative study conducted between January 2023 and June 2024 at Instituto Cearense de Oftalmologia (Fortaleza, Ceará, Brazil), in collaboration with the Innovation Laboratory of Technology at the Universidade Christus. The study was carried out by a multidisciplinary team of ophthalmologists and software engineers. The primary steps in creating and validating the PRESB application were: designing the user interface and implementing the app's native functions; validating the application among pseudophakic presbyopes who had undergone bilateral cataract surgery with implantation of monofocal intraocular lenses in both eyes, targeted for emmetropia, and who were evaluated at least 30 days after surgery in the second eye, using the System Usability Scale questionnaire; and analyzing the collected data on user satisfaction and usability.

Presbyopia is a common refractive condition that usually manifests in the fourth decade of life and progressively worsens during the fifth decade. This decline in near vision occurs when the crystalline lens can no longer become sufficiently spherical because of reduced ciliary muscle contractility and loss of elasticity.(⁸) A similar effect is observed after cataract surgery with removal of the crystalline lens, particularly when a monofocal IOL is implanted and emmetropia is targeted.

The impact of uncorrected presbyopia on daily activities and overall functional capacity is substantial.(⁹) Current treatments, such as progressive or bifocal glasses,(¹⁰) multifocal IOL implantation at the time of cataract surgery,(¹¹) and refractive surgery,(¹²) are often effective but may be associated with adaptation difficulties, financial cost, and the need for access to specialized ophthalmic services.

In this pilot, proof-of-concept feasibility and usability study, we focused on a single core feature of the PRESB application, near-image magnification, tested in a specific clinical setting of pseudophakic presbyopes after bilateral cataract surgery. Within this context, PRESB was associated with significantly better unaided near visual acuity and reading speed compared with baseline unaided near vision after monofocal IOL implantation, and it was rated as highly usable by participants (mean System Usability Scale score = 75.31 ± 7.29). Because the main mechanism is optical-digital magnification, an improvement in near performance relative to unaided near vision, it is expected and it should be interpreted as an "aid through enlargement," conceptually closer to a handheld magnifier than to refractive correction. Accordingly, PRESB is intended as an adjunct tool and not as a replacement for conventional near correction. Importantly, we did not compare PRESB with standard care (such as conventional near additions) or with existing smartphone magnifier applications, so the present results should be interpreted as an initial demonstration of feasibility rather than a comparative effectiveness trial. In particular, the lack of a direct comparison with reading glasses limits any inference about how PRESB performs against the current standard approach for near vision in presbyopia.

Beyond simple magnification, PRESB incorporates educational content, including videos that explain presbyopia and step-by-step instructions for configuring built-in smartphone accessibility features, resources that are not routinely available in similar applications for iOS or Android devices.(¹³) In the current version, the educational videos are delivered via an online platform and therefore require an internet connection, which may limit access in some real-world contexts. However, this educational component is designed to enhance user understanding and correct use of the tool: patients can view the instructional material when connectivity is available and subsequently retain the guidance for day-to-day use, while the core magnification function remains immediately accessible for rapid, opportunistic near tasks. In addition, native accessibility functions (including built-in magnifiers) already exist on some devices; however, PRESB integrates magnification presets, illumination support, contrast-friendly modes, image capture, and educational guidance within a simplified interface, which may facilitate adoption by older adults and by users who are less familiar with device settings. A practical advantage of PRESB is its usefulness for individuals with presbyopia who do not always have their reading glasses at hand. In everyday situations, such as reading menus with small print in dimly lit restaurants, checking bills or receipts, or examining product labels in supermarkets, the app offers immediate magnification through the smartphone camera. This may help reduce the discomfort or embarrassment that many users feel when they are unable to read important information related to prices or product details, thereby preserving autonomy and confidence in social interactions. Previous studies have shown that uncorrected presbyopia significantly compromises performance in near-vision tasks, reinforcing the importance of accessible interventions.(¹⁴) By combining high-contrast magnification presets, a simple, button-based interface and disease-specific educational content, PRESB may be easier for older adults to adopt than manually setting up native accessibility settings.

Some participants reported the impression that the application could replace their reading glasses in daily life. Although this perception illustrates the positive subjective impact of the tool, we emphasize that PRESB is intended as a complementary aid rather than a substitute for comprehensive refractive correction and regular ophthalmic follow-up. Moreover, while the observed differences were statistically significant, clinical relevance should be interpreted in functional terms (e.g., the ability to complete a near task in a real setting), and not solely based on p-values; as such, PRESB may be particularly useful for rapid, opportunistic reading tasks rather than sustained near work.

This study has some limitations. The sample size was relatively small and derived from a single center, which limits generalizability. There were no control group and no direct comparison with standard near corrections or with built-in smartphone magnifiers. The evaluation was short-term and based on a single visit, focused on immediate performance rather than long-term adherence. In addition, the reading tests were always performed in the same order, which may have introduced a learning effect. Finally, the study population consisted of post-cataract pseudophakic patients, so the findings may not directly apply to phakic individuals or to other presbyopic groups.

Near visual acuity was measured using Jaeger charts, an ordinal scale widely used in clinical practice; therefore, variability and dispersion measures derived from ordinal categories should be interpreted cautiously, and future studies should preferentially adopt continuous near-vision metrics when the primary objective is quantitative modeling of variability. In addition, the use of PRESB presupposes access to a smartphone and adequate battery charge, which may limit applicability in some settings. Because the application was developed by the study team, independent external validation will be important to mitigate potential investigator-related bias and to strengthen the evidence base.

Future work should include larger, multicenter, preferably randomized studies to confirm these preliminary findings and to better define the role of PRESB in presbyopia management. Comparisons with standard near additions and with native smartphone magnifier tools will be important to establish relative benefits and potential indications. Long-term studies incorporating real-world usage metrics, such as app analytics and adherence over time, could also help clarify how and when patients actually use the application in their daily lives. Daily-life assessments conducted outside a controlled clinical visit will be particularly valuable to determine sustained usability, situational barriers (e.g., connectivity and battery), and the contexts in which magnification-based assistance is most beneficial.

In summary, PRESB appears to be a viable and potentially useful tool for assisting patients with presbyopia, offering a positive user experience alongside a set of accessibility features. Its integrated educational resources may help users better understand their condition. As a free, complementary option, PRESB has the potential to play a meaningful role in vision care, particularly for individuals who have limited access to more advanced treatment options.(¹⁵)

The PRESB application proved to be effective and valid in achieving its main objective, as it led to a significant improvement in unaided near visual acuity compared with not using the application. It therefore appears to be a useful adjunct in the daily activities of individuals with presbyopia.