New Study Demonstrates Potential For Improving Glaucoma Diagnosis Across Europe
Newly published results from the European Optic Disc Assessment Trial (EODAT) reveal the accuracy of glaucoma diagnosis can be improved when patients' optic discs are assessed using common imaging devices, and suggests that post-graduate training courses in optic disc assessment would improve glaucoma care.1 Glaucoma is one of the leading causes of irreversible blindness worldwide.2 Approximately 50% of all glaucoma cases remain undiagnosed.3
The results echo the European Glaucoma Society's (EGS) recommendation for extended ophthalmologists' training in optic disc assessment to increase early diagnosis and improve glaucoma care in Europe.3 Earlier diagnosis and treatment can help to reduce the impact of disease progression, and hence the physical and financial costs associated with increasing disease severity.4
EODAT was supported by Pfizer Ltd with an investigator-initiated research grant. The study assessed the diagnostic abilities of 243 ophthalmologists from eleven countries across Europe.1 The accuracy of their assessment was compared with that of two specialist imaging devices, the GDx with variable corneal compensation (VCC) and the Heidelberg Retina Tomograph (HRT). One hundred and ten optic disc photographs were evaluated in total.1 The ophthalmologists made the correct diagnosis in 80.5% of all optic discs, whilst the GDx VCC and HRT accurately classified 93.2% and 89.8% of the eyes, respectively.1 These results indicate that imaging technologies can be used as tools to complement ophthalmologists' diagnoses, especially in patients with mild to moderate glaucoma, where optic disc damage is harder to recognise.
According to the trial's lead investigator Dr Nicolaas Reus of The Rotterdam Eye Hospital, "Glaucoma is a leading cause of blindness in the developed world, and late diagnosis can lead to irreversible damage to the optic nerve and loss of sight. The imaging devices in this trial had a high diagnostic accuracy and should therefore be used to support clinical assessment and improve early detection of this debilitating condition across Europe. Importantly, the progression of glaucoma can be slowed with early and accurate diagnosis if followed up with appropriate treatments to reduce intraocular pressure."
As indicated by the high variability in accuracy of the ophthalmologists' optic disc assessments, tackling the increasing burden of glaucoma on healthcare systems in Europe requires widespread and improved training.1
Mr Clive Migdal, President of the EGS reinforces the importance of education. He says, "Glaucoma is a devastating disease for so many Europeans and has a negative impact on their quality of life if it is not detected in its early stages and treated appropriately. Crucially, the results from this important study highlight the need for further training to further improve the rates of early diagnosis and alleviate patients' potential suffering. As stated in the 2008 edition of the EGS Guidelines, a diagnosis should never be based solely on imaging devices, as these are unable to compete with a clinician's many years of training and expertise."
About glaucoma
Glaucoma is a group of diseases that irreversibly damage the optic nerve.5 Early diagnosis and treatment are integral to effective long term treatment.3 One of the most important risk factors for glaucomatous damage is high intraocular pressure (IOP) caused by the build up of natural fluid (aqueous humor) produced by the eyes to keep them healthy and functioning normally.6,7 Impaired outflow of aqueous humor results in elevated IOP.7 Increased IOP damages the optic nerve and retinal ganglion cells undergo a slow process of cell death.7 The death of the retinal cells and degeneration of the nerve fibers result in permanent vision loss.7
The two most common forms of glaucoma are:
- Open-angle glaucoma - the most common form of the disease, open-angle glaucoma is progressive and characterised by optic nerve damage. The most significant risk factor for the development and advancement of this form is high eye pressure.
- Angle-closure glaucoma - may be acute or chronic. In acute angle-closure glaucoma, the normal flow of eye fluid (aqueous humor) between the iris and the lens is suddenly blocked.8 It is a medical emergency and must be treated immediately. Chronic angle-closure glaucoma progresses more slowly and can damage the eye without symptoms, similar to open-angle glaucoma.
Worldwide, an estimated 6.7 million people are blind from glaucoma, with approximately 70 million people living with the condition.9
About the study
Study investigators invited 875 general ophthalmologists from eleven European countries to participate. Fully completed score sheets were received from 243 individuals and study results were gained from these. Participants were presented with 110 optic disc slides, comprising 40 healthy eyes, 48 glaucomatous eyes and six with ocular hypertension (OHT). There were only two grading options provided per slide: normal or glaucomatous.1
For each participant and imaging technique, the sensitivity, specificity and overall accuracy were calculated. In addition, the diagnostic accuracy was calculated for each country by averaging the above criteria. The accuracy varied between 61.4% and 94.3% among clinicians, with an average of 80.5%. In comparison, the imaging devices had a higher overall diagnostic accuracy of 93.2% (GDx VCC) and 89.8% (HRT).1
Pfizer Ltd supported EODAT with an investigator-initiated research grant. Pfizer had no role in the design or conduct of this research, in the data collection, analysis, and interpretation, in the preparation of the manuscript, nor in the decision to submit the paper for publication. The manuscript was published online at Ophthalmology, the official journal of the American Academy of Ophthalmology, as an Article in Press on 4 January 2010.
References
1. Reus NJ, Lemij HG, Garway-Heath DF, et al. Clinical assessment of stereoscopic optic disc photographs for glaucoma: the European Optic Disc Assessment Trial.Ophthalmology. Available here. Accessed 05 January 2010.
2. World Health Organization. Bulletin of the World Health Organization. In Focus, Nov. 1 2004. Available here. Accessed 03 November 2009.
3. European Glaucoma Society. Terminology and Guidelines for Glaucoma (3rd edition). 2008.
4. Traverso CE, Walt JG, Kelly SP et al. Direct costs of glaucoma and severity of the disease: a multinational long term study of resource utilisation in Europe. Br J Ophthalmol. 2005;89;1245-1249.
5. National Eye Institute. Glaucoma Defined. What is glaucoma? Available here, Accessed 03 November 2009
6. The Glaucoma Foundation. Who's At Risk? Available here. Accessed 03 November 2009
7. The Glaucoma Foundation. About Glaucoma. Available here. Accessed 03 November 2009
8. National Glaucoma Research - A Program of the American Health Assistance Foundation. Available here. Accessed 03 November 2009
9. Congdon NG, Friedman DS, Lietman T. Important Causes of Visual Impairment in the World Today. JAMA. 2003; 290: 2057-2060.
Source
Pfizer