The Education Committee carefully selects presentations from the World Glaucoma Congress 2017 in Helsinki for your benefit. This edition Olusola Olawoye gives the introductions for the sessions OCT in glaucoma: present and future, Patient oriented symposium and Perfecting the art of glaucoma phenotyping.
OCT in glaucoma: present and future
Kouros Nouros Mahdavi gave an excellent talk on structure-function relationship. He said it provided complementary information and helped in the confirmation of disease or progression and also helped in prediction of disease. He compared OCT and SAP and gave several reasons why structure and function may disagree. He mentioned that glaucoma severity influences structure and function relationship and that inter individual variability was more than intra eye variability. He said that customization could improve structure function relationship. All structural parameters have a measurement floor because of the blood vessel glial tissue and the remaining connective tissue in the retina. He added that structural measurements can predict functional progression. He concluded by saying that structure and function can be unified into a single index and longitudinal Structure Function relationship can help with determination of progression.
Ki Ho Park spoke about ganglion cell analysis in glaucoma. He described the ganglion cell- inner plexiform layer (GCIPL). This layer is composed of dendrites and cell body while the nerve fiber layer is composed of axons. He said there was no difference in the diagnostic ability of GCIPL, retinal nerve fiber layer thickness and rim area parameters. He mentioned that the inferior portion of the macula is more vulnerable to damage and it corresponds to the 8 o’clock region. He said that more than one test would be needed to confirm glaucoma in myopic. He concluded by saying that the glaucoma detection ability of the macular GCIPL analysis was comparable to that of the peripapillary RNFL thickness. For discrimination of early glaucomatous structural loss most notably in pre-perimetric glaucoma cases, identification of the GCIPL thickness difference across the horizontal raphe was effective. He also mentioned that in early glaucoma the macular GCIPL change is frequently detected before corresponding RNFL change.
Christopher Leung described the Guided Progression Analysis of the OCT as a tool for evaluating follow up and baseline RNFL thickness. He mentioned however that the GPA does not measure the rate of RNFL thinning and it can be less sensitive than trend analysis to detect change. He described the trend based progression analysis and said it could detect change earlier than GPA. He also said that eyes with progressive RNFL thinning were more likely to develop subsequent visual field loss (VF). Progressive RNFL thinning confers an 8- fold increase in risk of subsequent VF loss and progression. He concluded that structural changes are predictive of future loss of visual function.
David Huang gave his talk on OCT angiography and its relevance in glaucoma management. He started by describing the physical properties of the OCTA. Glaucoma reduces perfusion at multiple levels of the optic nerve head, peri-papillary and macular retina and it also reduces the peripapillary retinal vessel density. He discussed the flow projection artifact. Glaucoma mostly affects the superficial vascular complex (SVC) and the peripapillary radial capillary plexus but relatively spares the intermediate and deep capillary plexuses. He concluded that vessel density measurement provided high diagnostic accuracy and good correlation with visual field parameters although larger OCTA scans performed better. In addition, SVC had slightly higher diagnostic accuracy compared to the ganglion cell complex. In the future OCTA based visual field simulation may be possible.
Catherine Liu talked about the usefulness and limitations of OCT in glaucoma management. She said that OCT was useful in quantitative assessment of progression in glaucoma. She also said that OCT may help confirm the presence of structural damage in the absence of visual field defects. OCT is also a unique tool to detect structural damage in glaucoma patients with unreliable visual field. She mentioned that OCT may miss slit retinal nerve fiber layer defect and disc hemorrhages. She said that false positive rate was high with OCT in patients with high myopia therefore caution should be exercised in interpreting the results. She mentioned that one advantage of fundus photography over OCT is that it provides a more comprehensive view of the fundus and helps to diagnose co-existing retinal diseases. Red free photos is good for detection of progression if there is no diffuse RNFL loss, no high myopia and no optical medium opacity. She mentioned that retinal pathologies may cause segmentation errors and therefore changes in OCT measurements may not be related to glaucoma. She concluded that OCT and fundus photos were useful tools in the management of glaucoma.
Patient oriented symposium
This was a very interesting session on patient oriented outcomes in glaucoma management. Pradeep Ramulu in the first talk highlighted the psychological, physical and emotional problems faced by glaucoma patients. Glaucoma patients may have problems with reading, mobility, self-care tasks and social interaction. He highlighted that glaucoma patients may have reduced reading speed, experience more falls, stop driving, have slower reaching for objects, slower object searches and poor facial recognition in late disease. He concluded his talk by reiterating that glaucoma affected many aspects of daily function and safety.
August Colenbrander spoke about the importance of rehabilitation as a component of comprehensive glaucoma care. He concluded that glaucoma rehabilitation was a neglected field and more education was needed by clinicians, patients and rehabilitation workers.
Jack Ciofi talked about integrating vision rehabilitation into ophthalmic training He described his experience at the lighthouse guild and how they had collaborated with this facility to train residents on rehabilitation using both online training and practical exposure. Residents had training programs that spanned all the three years of residency training. In the first year they achieved cognitive milestones, in the second year, technical milestones and in the third year they had practical and constant interactions with patients. He discussed the importance of integrating vision rehabilitation into the resident’s curriculum world- wide.
Professor Geoff Pollard discussed what the ophthalmologist in the developed world should be doing using Australia as an example He noted that the fastest growing age group was 100 years and more and talked about how this was going to influence glaucoma care. He mentioned that about 2% of the population had glaucoma but only 50% were diagnosed and of these only 50% adhered to their medication therefore only 25% were likely to have been treated. He mentioned that 25% of those who were diagnosed had significant visual impairment or were blind at diagnosis. He described the patients journey from the community before diagnosis to diagnosis and to lifelong management. He concluded that the Ophthalmologists as leaders of the eye team should foster a collaborative approach to care and influence all stages of glaucoma patient care.
Olusola Olawoye spoke about the wide continuum of developing countries and focused her discussion on the least developing countries where resources are grossly sparse. She noted from the meta-analysis by Tham et al that Africa and Asia would be responsible for the highest increase in glaucoma prevalence in the future due to an increased life expectancy. She focused mainly on the importance of appropriate, cheap and sustainable approaches to glaucoma care in developing countries.
Perfecting the art of glaucoma phenotyping
Michael Coote gave the first talk on the disc. He described the GONE (Glaucoma Optic Neuropathy Evaluation) project, an internet-based system which is a readily accessible and standardized tool, for clinicians globally, that permits self-assessment and benchmarking of skills in optic disc examination.
He mentioned that optic nerve head (ONH) assessment was hard to teach and learn in the clinic and there were very few randomized controlled trials in education. He gave a fantastic presentation on the agreement consistency of optic disc evaluation between experts’ trainees and optometrists. He presented some factors that may result in overestimation and underestimation. There may be overestimation of cupping when the disc is large and the converse is the true for small disc. In tilted disc, the tendency is to overestimate the cupping and this is worse with a vertical tilted disc.
Ananth Viswanathan gave the second presentation in which he focused on the visual field. He mentioned that there were basically 4 domains to getting the most out of visual fields: infrastructure, technical staff, clinical staff and patients. He mentioned that 6 visual fields were necessary in the first 2 years for newly diagnosed manifest glaucoma. He stressed the need for properly trained technical staff and guidelines/protocol/standard operating procedure to guide the staff. He also mentioned that visual field progression can be assessed based on event (GPA) analysis and trend (progressor) analysis. He concluded that it was important for patients to be properly counselled on how to do the visual field test to get the best and most reliable result.
Susan Williams gave a fascinating presentation on how to incorporate family history and genomics into practice. She mentioned that family history was one of the most important risk factors for POAG. Persons who had a first degree relation with POAG had a 7 to 10 times greater risk of developing the disease than the general population. Up to 50% of POAG patients have a family history of glaucoma. Family history can direct genetic enquiry in the following important ways: they can provide valuable phenotypic information and it may be able to define the pattern of inheritance. She mentioned that more than 20 recognized gene loci had been identified as etiologic cause of POAG but GLC1 gene loci is still the most important, accounting for 3 to 5% of all POAG.
She concluded that the future of glaucoma care in terms of genomics is Precision Medicine. She defined precision medicine as a customized healthcare where medical decisions, practices or products are tailored to the individual patient. It is currently being used in cancer treatment and in the near future it will be used in other field of medicine, including glaucoma care.
Gus Gazzard talked about gonioscopy. He mentioned that the assessment of the angle begins with anterior chamber depth assessment. Several alternative to gonioscopy has been put forward over the years (UBM, AS-OCT with dedicated infrared cameras and viewing optics), yet none has been able to take the place of a good gonioscopy. He discussed the Foster fundamental questions which are critical to assess for iridotrabecular contact and detect angle closure. He spoke about the important landmarks during gonioscopy and recommended gonioscopy.org for practical video viewing of the anterior chamber angle.
John Brookes talked about phenotyping the abnormal anterior segment in relation to congenital and pediatric glaucoma. He talked about anterior segment dysgenesis (ASD) and the gene responsible for the condition PITX2 (4q25). He described ASD as a failure of normal development of the anterior segment and a disorder of neural crest cell migration. It is an autosomal dominant disorder and very often presents at birth. It is typically bilateral and children with this dysgenesis have a 50% risk of developing glaucoma. He described in details the clinical features, management and prognosis of ASD.