Keratoconus (KC) is a progressive corneal ectatic disorder characterized by thinning and conical protrusion of the cornea, resulting in irregular astigmatism and visual distortion.^(1,2) Onset typically occurs during adolescence or early adulthood and may significantly impair quality of life, academic performance, and professional functioning. In advanced cases, untreated KC may lead to severe visual loss or legal blindness.⁽³⁾ Early diagnosis is critical, as timely interventions, particularly corneal collagen cross-linking (CXL), can halt progression and preserve vision, potentially avoiding the need for corneal transplantation.^(4,5)

Despite diagnostic and therapeutic advances, KC remains poorly understood by the general public. Its relatively lower recognition contributes to low awareness. Global prevalence estimates range from 0.2 to 4,790 per 100,000 persons to as high as 5% in some populations.⁽⁶⁾ In Brazil, although epidemiological data are limited, KC is recognized as a significant cause of visual impairment among young adults.⁽⁷⁾

Lack of public knowledge may delay care and worsen outcomes.⁽⁸⁾ Risk factors such as frequent eye rubbing are often underestimated, while disease severity may be exaggerated, causing unnecessary fear or stigma.^(9,10) Understanding public perceptions and correcting misconceptions are essential for effective health education.⁽⁸⁾ Initiatives like the global Violet June campaign promote early diagnosis and discourage harmful behaviors.⁽¹¹⁾ However, their success depends on baseline knowledge, which remains poorly documented in Brazil.^(12,13)

Similar international surveys have also revealed limited public understanding of KC, with studies in Europe and the Middle East reporting low knowledge levels and frequent engagement in risk behaviors such as eye rubbing.^(9,14,15)

This study aimed to evaluate public knowledge of KC in Brazil and identify gaps to guide future educational strategies.

A descriptive cross-sectional survey was conducted between June and August 2024 to assess KC knowledge in the general Brazilian population. The study followed the Declaration of Helsinki and received approval from the Institutional Research Ethics Committee (protocol no. 6.584.843/2023; CAAE: 76077522.7.0000.5258). Participation was anonymous and voluntary, with electronic informed consent obtained at the start of the questionnaire. A structured questionnaire was developed specifically for this study, based on key topics from the 2015 Global Consensus on Keratoconus and Ectatic Diseases (Supplementary Material - Chart 1S). It was written in Portuguese, reviewed by two ophthalmologists, and pilot-tested on laypersons for clarity. The final instrument included 25 main questions across three domains: participant demographics (age, sex, education, and region); ocular history (presence or knowledge of KC, allergy history, eye rubbing frequency, and refractive correction); and KC knowledge (etiology, symptoms, treatments, and common misconceptions). Knowledge questions were presented as multiple-choice or true/false items. All participants, regardless of prior awareness, were required to respond to knowledge questions, even if by guessing.

The survey was hosted on Google Forms and distributed through social media platforms (Facebook, WhatsApp, Twitter) and via an ophthalmology newsletter (Oftalmologia em Foco). A convenience sampling strategy aimed to reach both individuals with KC and members of the general public. Inclusion criteria included age ≥18 years, Brazilian residency, and Portuguese comprehension. A total of 912 responses were received; after excluding incomplete responses and ineligible participants, 879 were included in the final analysis (3.38% margin of error and 95% confidence level).

The primary outcomes were the proportion of correct and incorrect answers to each knowledge question and their association with demographic or clinical variables. Misconceptions were defined as incorrect beliefs that contradicted scientific consensus.

Data were analyzed using Statistical Package for the Social Sciences (SPSS) version 20.0. Categorical variables were presented as frequencies and percentages, while age was summarized as mean ± standard deviation. Associations between knowledge and participant characteristics were assessed using chi-square or Fisher's exact tests. Nonparametric tests (Kruskal-Wallis with Dunn-Bonferroni post-hoc corrections) were used for continuous or ordinal comparisons when appropriate. Spearman's correlation was used to evaluate associations between numerical variables. All tests adopted a 5% significance level.

This study presents a comprehensive overview of the knowledge of Brazilian population on KC, a relatively under-recognized condition despite its clinical significance. The results reveal substantial gaps and misconceptions among both individuals diagnosed with KC and the general public. To our knowledge, this is the first large-scale cross-sectional survey in Brazil to quantitatively assess awareness and understanding of KC in a diverse sample, including both patients and non-patients.

The finding that 45.8% of respondents had never heard of KC underscores a critical need for public health education. Although the disease is less prevalent than refractive errors or cataract, its progressive and potentially sight-threatening nature, particularly if not diagnosed early, makes timely recognition essential.⁽¹⁶⁾ The lack of awareness may delay diagnosis and treatment, increasing the risk of vision loss and reducing quality of life.⁽¹⁷⁾

Among those who had heard of the disease, many held misconceptions about its causes and treatment. Although the majority recognized blurred vision and visual distortion as symptoms, only 52% correctly identified the multifactorial etiology of KC, and 55% incorrectly believed it inevitably leads to blindness. These findings highlight the need to clarify not only the nature of the disease but also its prognosis, particularly emphasizing that KC is not a blinding disease when properly managed.⁽¹⁸⁾

There are several refractive surgical approaches available for the treatment of KC, including surface ablation, intracorneal ring segments, phakic intraocular lenses, and corneal CXL, which can be used alone or in various combinations depending on the patient's corneal regularity and disease stage.⁽¹⁹⁾ An important observation is the low awareness of modern therapeutic options, even among those diagnosed with the disease. Corneal collagen CXL, currently the gold standard for halting KC progression, was unknown to 40.7% of patients with the condition.⁽²⁰⁾ Similarly, 20.7% were unaware of intracorneal ring implants, and 13.1% believed that corneal transplantation is the only surgical option. These data suggest that information is either not reaching patients adequately or is not being retained, raising concerns about communication strategies during consultations.⁽²¹⁾

The study also sheds light on the persistence of harmful behaviors, such as frequent eye rubbing. While 88.7% of respondents acknowledged that eye rubbing can cause or worsen KC, nearly a third still reported engaging in this behavior daily. This gap between knowledge and behavior emphasizes the need for practical guidance on how to change habits, especially in patients with allergic conjunctivitis.⁽²²⁾ It also suggests that risk communication alone may be insufficient without personalized behavioral interventions. This behavioral contradiction, wherein patients acknowledge harmful habits yet persist in them, finds further context in the international study by Baenninger et al., which revealed that none of the KC patients surveyed met the minimum disease knowledge standard expected by specialists.⁽¹⁴⁾

Another noteworthy point is the role of education and exposure in shaping disease understanding. Participants with higher educational attainment and personal experience with KC (either self or via acquaintance) consistently performed better across knowledge domains. In contrast, older adults and individuals with lower education levels were more prone to misconceptions. These findings are consistent with the broader literature on health literacy and reinforce the need for tailored educational materials that address different audiences, including simplified language and visual aids for those with limited health literacy.^(8,23)

Encouragingly, most respondents acknowledged the importance of psychological and multidisciplinary support, with 92% agreeing that mental health support can aid patients in coping with KC. This aligns with previous qualitative studies suggesting that KC, particularly in younger individuals, can lead to emotional distress, reduced self-esteem, and anxiety about vision loss.⁽²⁴⁾ The recognition of this need by both patients and non-patients supports integrating psychosocial care into KC management protocols.⁽²⁵⁾

Even among individuals diagnosed with KC, key misconceptions, such as believing it inevitably leads to blindness or is only treatable by surgery, remained common, highlighting serious gaps in patient education. These findings suggest that clinical consultations may not be effectively conveying essential information. Given that KC often begins in adolescence, these results also support the implementation of school-based education and screening programs. Targeted public health policies in educational settings could promote early detection, discourage harmful behaviors like eye rubbing, and improve long-term visual outcomes.

From a public health standpoint, the findings provide strong support for awareness campaigns such as the international initiative Violet June, which promotes early diagnosis and highlights modifiable risk factors.⁽¹¹⁾ However, the effectiveness of such campaigns depends on reaching populations with little or no prior awareness, precisely the group most at risk of being overlooked. This study provides evidence-based direction for campaign design, particularly suggesting emphasis on debunking myths (e.g., blindness inevitability), reinforcing modern treatments, and highlighting the role of prevention (e.g., managing allergies, avoiding eye rubbing).

The results also have implications for clinical practice. Ophthalmologists and optometrists should ensure that all patients receive complete, understandable information about their diagnosis and treatment options. Tools such as printed educational materials, brief videos, or patient support groups may help reinforce messages conveyed during consultations. Clinicians should also actively correct misconceptions and check patient understanding during follow-up visits.⁽⁸⁾

This study reveals significant gaps in the Brazilian population's knowledge about keratoconus, particularly regarding its etiology, prognosis, and available treatments. While some understanding exists, misconceptions remain prevalent, even among patients. These include the belief that keratoconus inevitably leads to blindness or that it is only treatable with surgery. Low awareness of effective treatments such as corneal cross-linking and intracorneal rings highlights the need for improved communication between healthcare providers and patients. Additionally, the strong association between knowledge and factors such as educational level, age, and prior exposure to keratoconus emphasizes the importance of targeted public health strategies. Ultimately, improving knowledge about keratoconus has the potential to enhance clinical outcomes, reduce psychological burden, and support long-term visual health.