New Ideas in Glaucoma
Neurovascular coupling in glaucoma
Vascular dysregulation in glaucoma has already been demonstrated: impaired autoregulation, decreased blood flow, reduced vessel caliber. However, the exact mechanisms are still unknown. In this context, Prof. Adriana Di Polo starts her lecture. In her laboratory, researches regarding neurovascular coupling are being performed. Neurovascular coupling is the ability of the system to increase blood flow according to metabolic demand of active ganglion cells. She demonstrates how to perform imaging of retinal microvasculare in animal models and which differences between ocular hypertension and controls may occur.
According to her data, there are evidences for pericyte-mediated neurovascular dysfunction in glaucoma. Also, strategies to protect pericyte-to-pericyte nanotubules, essential for neurovascular coupling, may be beneficial for neurovascular health, she says. This an interesting research line, explained in detail in this video presentation.
Track my visual field in lockdown…
It is well known that one of the burdens of glaucoma disease is the number of visits and tests required for proper follow-up. Visual field testing is part of glaucoma evaluation and the endpoint of clinical trials. However, on daily basis, perimetry is a challenge for many patients. In this context, Prof. David Crabb presents his results with the Eyecatcher, a portable and simple visual field testing that can be used at home.
In the first version, he says, patients were asked to move their eyes and follow a stimulus which was presented in the screen of a digital tablet. Real world results of this device are presented in this lecture. Moreover, Prof. Crabb also demonstrates the results obtained with a home version of the Eyecatcher. With reproducible results, good correlation with standard Humphrey visual fields and low variability, this seems to be a promising technology. Stay up to date with Prof. Crabb’s lecture!
ON or OFF? Asymmetric responses in glaucoma
This lecture was presented by Prof. Yvonne Ou starts explaining that glaucoma may be considered a disease model to study neural circuit disassembly. In her laboratory, Prof. Ou induces IOP elevation in mice, after a session of laser photocoagulation. IOP returns to previous baseline levels after seven days. However, pressure elevation causes ganglion cells loss after 14 days. Ganglion cells may be divided into ON and OFF responders, according to light increments and decrements, she explains. ON-sustained retinal ganglion cells (RGCs) maintain dendritic area and increase receptive field size. The opposite occurs with OFF-transient RGCs.
Also, ON-sustained RGCs are more resilient to IOP elevation, while OFF GCC are lost. Besides, ON-sustained RGCs show decreased synaptic density after IOP elevation. The translation of this asymmetric response between ON and OFF RGCs is a point of interest. Using electroretinography (ERG), changes in the ON and OFF-pathways can be measured. Prof. Yvonne continues her lecture, presenting recent data regarding her studies with ON and OFF RGCs.
Meditation
Prof. Tanuj Dada brings us recent information regarding how meditation can influence intraocular pressure. Meditation, he explains, is a technique to bring mental processes under greater voluntary control, leading to general mental well-being. In his talk, he emphasizes the importance of addressing the negative emotions associated with the diagnosis of glaucoma.
There are evidences that depressive symptoms are linked to fast glaucoma progression. Since primary open glaucoma patients are high steroid responders, it is reasonable to consider that endogenous cortisol elevation may be linked to higher IOP levels. Prof. Tanuj presents data to support the concept that meditation may increase parasympathetic activity and even improve blow flow in cerebral cortex. He also demonstrates how mindfulness meditation may reduce IOP and stress biomarkers. This video session is a perfect starting point to understand his conclusion: “Treat the eye as well as the patient behind the eye”!
Is there any (artificial) intelligence in angle closure glaucoma?
In this presentation, Prof. Chris Leung talks about how deep neural network can be used to detect gonioscopic angle closure. Angle closure, he says, is typically defined with dark room gonioscopy, when the posterior trabecular meshwork is invisible for at least 180 degrees. The improvement of imaging devices, he says, has facilitated evaluation of the anterior portion of the eye. In less than one second, the entire anterior segment can be scanned with OCT.
However, anterior segment OCT (AS-OCT) is still not routinely adopted in clinic practice to detect angle closure. Why? According to Prof. Leung, the fundamental question is how to define angle closure based on AS-OCT images, as well as how to identify gonioscopic angle closure with this device. To answer these questions, the Angle Closure Imaging Consortium now tries to define the optical diagnostic criteria, since the nature of angle closure, based on images, is different from gonioscopy. Furthermore, he says, deep neural network may help to improve angle closure detection with AS-OCT. This promising technology, as well as recent published data, are presented in this talk.
