Visual impairment (VI) is one of the most challenging disabilities worldwide. An increasing number of people are at risk for VI caused by chronic eye diseases due to the globally growing elderly population [
1]. Therefore, the requirement for visual rehabilitation is estimated to increase in the near future [
2]. In Germany, there are estimated to be 1.1 million visual impaired persons (Visual acuity, VA < 6/18), in addition to 160,000 legally blind people (WHO Grade 4, VA ≤1/60) [
3,
4]. The most common causes for VI in Germany are age-related macular degeneration (AMD), glaucoma and diabetic retinopathy [
2]. A smaller group of patients suffers from VI due to corneal diseases, like corneal opacities caused by thermal/chemical burns, corneal dystrophies and ocular graft versus host disease (GvHD), as well as keratoconus. Most cases can be treated successfully with surgical methods like perforating keratoplasty (PK), descemet membrane endothelial keratoplasty (DMEK), deep anterior lamellar keratoplasty (DALK), amnion membrane transplantation and limbal stem cell transplantation. However, due to ocular risk factors, like vascularization, uncontrolled intraocular pressure (IOP) and uveitis some patients cannot be treated successfully with these procedures [
5]. In addition, some patients cannot undergo surgery due to comorbidities, like heart diseases or refuse surgery as a result of their age or fear. Even patients who can be treated with surgery often wait months to years for a graft, depending on the procedure. Patients with keratoconus can usually be treated with contact lenses, but some patients suffer from pain while wearing and cannot endure this treatment. Besides these reasons, insufficient health insurance can also keep patients from optimal medical care. All these patients have to endure VI and its consequences, which comprise, besides reading disability, problems in performing tasks of daily living and social interactions. These problems lead to a decreased self-sufficiency and more dependency on relatives and caring persons. Due to these detrimental consequences several studies were able to show, that the quality of life of visual impaired patients is drastically decreasing and there is a higher prevalence of depression [
6‐
8]. Furthermore, patients have more accidents and falls, which leads to a higher morbidity and mortality [
9]. Patients with VI should hence undergo visual rehabilitation. By making best use of the remaining vision, rehabilitation aims to improve mobility, reading ability, and consequently autonomy of patients. By low vision aids (LVAs), like optical magnifiers, electronic desk video magnifiers (closed-circuit television, CCTV) and portable electronic vision enhancement systems (p-EVES) reading ability can be improved or restored and consecutively quality of life as well [
10‐
15]. The adaption of the suitable LVA for each patient is depending on the disease, the magnification requirement, former reading behavior and other individual factors [
16,
17]. Furthermore, the best LVA is highly depending on the task it will be used for. Since electronic LVAs are much more expensive compared to optical LVAs, visual rehabilitation should incorporate this as well [
18]. Therefore, the visual rehabilitation process is very complex and time consuming [
19]. Due to glare sensitivity and other concomitant problems, like dry eye, adaption of LVAs is especially difficult in patients with corneal diseases. Although it is known that the underlying disease is important for visual rehabilitation there is no published data regarding these patients [
16]. This probably results from the rareness of irreversible VI due to corneal diseases. Most studies rather focus on the main causes for visual impairment, like AMD [
19,
20]. The best contrast settings have also only been evaluated for retinal diseases [
21‐
23]. To evaluate LVAs, it is a necessity to measure the reading speed of the patients to show that reading performance can be improved and quantify this improvement, according to a Cochrane Review [
24]. This can be done by single sentences charts (Radner, MNREAD) or paragraphs, like the International reading speed texts (IReST). We chose IReST to measure reading speed, because it represents leisure reading (books, newspaper) and provides standardized paragraphs matched for linguistic difficulty to assess reading speed in repeated measurements [
10,
25,
26]. Apart from that, it is recommend that patients’ preference and characteristics should be assessed [
24]. Therefore, in this prospective, randomized cross-over trial, we aimed to characterize patients with visual impairment due to corneal diseases and evaluate the best low vision aid for this group in terms of objective reading performance and patient-reported rating.