While cataract is the most prevalent cause of reversible loss of vision, glaucoma remains the leading cause of irreversible blindness, characterized by a progressive optic neuropathy with degeneration of retinal ganglion cells and visual field loss. Glaucoma negatively affects low-luminance contrast sensitivity, glare symptoms, and dark adaptation time more frequently than any other domain. Therefore, when choosing the type of lens to implant in these patients, concerns arise regarding contrast sensitivity (CS) loss and subjective visual disturbances, which may be more debilitating and can also be a limitation when choosing IOLs.
Monofocal IOLs have been shown to be the safest IOL choice for patients with glaucoma. Multifocal IOLs provide spectacle independence but, due to the technology used combined with the pathological changes in glaucoma, tey can cause more visual disturbances, which makes them a relative contraindication in eyes with glaucoma.
Recent studies have demonstrated that EDOF IOLs can be safely be implanted in eyes with mild, pre-perimetric open-angle glaucoma with favourable uncorrected distance and intermediate visual acuity outcomes. Additionally, contrast sensitivity measurements also have been shown to be favourable in this patients and satisfactory spectacle independence and patient satisfaction in the subjective questionnaire.
However, it is yet unknown if EDOF IOLs could be an equal or a better option in patients suffering from cataracts and glaucoma, compared to a Monofocal lens made of the same material, since this could provide wider options when choosing the IOL and could offer spectacle independence for intermediate and distant vision for these patients.
Rationale and positioning with regard to the state-of-the-art Cataract surgery is one of the most performed surgeries worldwide, where the natural lens of the eye is removed and replaced by an artificial intraocular lens (IOL) with the aim of replacing its functions of focusing on objects at different distances. While cataract is the most prevalent cause of reversible loss of vision, glaucoma remains the leading cause of irreversible blindness, characterized by a progressive optic neuropathy with degeneration of retinal ganglion cells and visual field loss. It is estimated that one in five people undergoing cataract surgery have glaucoma or ocular hypertension, with the incidence of both cataract and glaucoma increasing with age.
Glaucoma negatively affects low-luminance contrast sensitivity, glare symptoms, and dark adaptation time and extent. Patients report problems with lighting and dark adaptation more frequently than any other domain. These problems worsen with progressing visual field loss. Some studies have reported that early-stage glaucoma patients experience significantly more difficulties in low-luminance or changing lighting conditions than age-matched controls. Therefore, when choosing the type of lens to implant in these patients, concerns arise regarding contrast sensitivity (CS) loss and subjective visual disturbances such as glares and haloes, which may be more debilitating and may be also a limitation when choosing certain IOLs.
Currently, there are four main groups of IOLs: monofocal, enhanced monofocal, extended depth of focus (EDOF), and multifocal lenses. All of them provide different types of vision with different types of optical technology, which can make the patient to be more or less a candidate to wear them.
Monofocal IOLs provide excellent outcomes for distant vision, with the benefit of generally low cost and low frequency of photic phenomena such as glares and haloes.Therefore, they are the safest IOL choice for patients with pre-existing ocular pathology, like glaucoma, as they do not split light. However, as they only provide one focus point, they fail to deliver spectacle independence for near and intermediate vision.
Compared with traditional monofocal IOLs, premium IOLs, like Multifocal (MF) and Extended Depht-of-Focus (EDOF), offer the benefit of better unaided visual acuity, greater spectacle independence, and higher patient satisfaction.
MFIOLs, come in varying optical designs, such as diffractive, refractive, bifocal, trifocal, or hybrid IOLs, and provide multiple focal points, which allows the patient to see at different distances. However, pathological changes in glaucoma may also potentially interact with the optical effects of MFIOLs, as they tend to cause more halo or glare symptoms due to light scattering at the transitional zone between the distant and near focus of the lens, fact that makes them a relative contraindication in eyes with glaucoma.
EDOF IOLs use a recent technology that creates a single elongated focal point to enhance depth of focus and range of vision, effectively providing satisfactory near and intermediate vision while addressing limitations of MFIOLs, including negative photic phenomena such as glares and haloes. In addition, they also have provided superior intermediate and near vision and a similar visual disturbance profile compared with an aspheric monofocal IOL.
They enhance correction of chromatic aberration and maintain good CS that may be comparable to that of monofocal IOLs. Due to this characteristics, this type of lenses may be an option for glaucoma patients.
EDOF IOLs' behaviour is still not well understood as there have been conflicting results regarding CS outcomes. Certain studies have demonstrated a decrease in CS in eyes with EDOF IOLs under scotopic conditions, compared to eyes with monofocal IOLs while other studies reported no significant difference, and some others reported that EDOF IOLs performed significantly better than trifocal IOLs under both photopic and scotopic conditions. However, new EDOF IOLs have appeared safe and efficacious when implanting it patients with early to moderate bilateral glaucoma, warranting further studies in this population.
Today, choosing a monofocal IOL in patients with glaucoma is the most recommended option and the safest one, given the lack of interference of its optical technology with the optico-pathological changes produced by glaucoma. Most IOLs today use a new type of optical technology that allows the patient to be spectacles independent or independent for near and intermediate vision, which is a great advantage. However, this type of technology is not well tolerated by glaucoma patients, meaning that they have fewer options when choosing an IOL compared to the standard population, that they cannot benefit from this premium technology, and that, therefore, it makes them dependent on glasses for near and intermediate vision. However, despite controversies, EDOF IOLs have proven to be somehow effective in glaucoma patients.This study aims to find out if an EDOF IOL could help to open up a door for these patients, by analysing its behavior compared to a monofocal lens made of the same material and by obtaining the effect of this lens on the visual acuity in at different distances and, additionally, to evaluate the CS and the photopic phenomena like glares and halos.
