A recent article from BMC Ophthalmology evaluated the effect of one hour of continuing medical education (CME) of subjective assessment of optic nerve head appearance on sensitivity and specificity for the diagnosis of glaucoma. Although the overall number of correct classifications only increased from 69 percent up to 72 percent on average, diagnostic sensitivity increased significantly from 70 percent up to 80 percent and the number of photographs classified as uncertain decreased significantly from 22 percent to 13 percent.
Background
In clinical practice, assessment of glaucomatous changes of the optic nerve head (ONH) may be the first step to detect glaucoma. Inspection of the posterior pole by e.g. ophthalmoscopy is a routine examination in most eye clinics. A suspect ONH appearance often directly leads to further examinations including perimetry and tonometry, or to referral of the patient. ONH assessment is sometimes a difficult task, particularly at early stages of glaucoma, requiring careful observation and knowledge about variability of optic disc appearance among healthy subjects and the characteristics of glaucomatous damage.
During the last two decades new computerized image techniques measuring and analyzing ONHs were developed. However, these image techniques are typically applied on patients already having a diagnosis of glaucoma or suspect glaucoma, and are not standard examinations in patients visiting eye departments/clinics for reasons other than suspect glaucoma or glaucoma. Therefore, subjective evaluation of the ONH, by e.g. ophthalmoscopy, is still important and often remains the first step when diagnosing previously undetected glaucoma.
A number of earlier studies have reported diagnostic accuracy of subjective assessment of the ONH, but the authors found no studies on the effect of CME on diagnostic accuracy of subjective optic disc assessment of residents in ophthalmology or of ophthalmologists.
Study and Methods
The aim of the study was to evaluate the effect of one hour of CME of ophthalmologists on the subjective grading of ONH photographs from glaucoma patients and healthy individuals. To carry out the study, ophthalmologists and residents in ophthalmology attending an international glaucoma meeting in March 2008, arranged at Malmö University Hospital, Malmö, Sweden, were asked to grade optic nerve head (ONH) photographs of healthy and glaucomatous subjects at two sessions separated by a lecture on glaucoma diagnosis by ONH assessment.
Each grader had access to an individual portfolio of 50 ONH photographs randomly selected from a web-based data bank including ONH photographs of 73 glaucoma patients and 123 healthy subjects. The individual portfolio of photographs was graded before and after the lecture, but in different randomized order.
Allergan Norden AB funded the work with the web-based database questionnaire. The study was supported by the Swedish Research Council, The Herman Järnhardt Foundation, The Foundation for Visually Impaired in Former Malmöhus län, and Crown Princess Margareta’s Foundation for Visually Impaired.
The lecture in ONH assessment for glaucoma diagnosis was performed by one of the authors (AGB). It was a one hour lecture based on Dr. Remo Susanna’s course “How to assess the optic nerve head and the retinal nerve fiber layer in glaucoma”, with definition of five rules to detect glaucoma. The lecture presented a systematic approach to evaluate optic discs with regards to glaucoma detection and focused particularly on the evaluation of optic disc size, neuroretinal rim, retinal nerve fiber layer, parapapillary atrophy and disc hemorrhages.
All ONH photographs shown in the lecture were selected by the lecturer and were extracted from an independent database of glaucoma patients and healthy subjects collected at the Department of Ophthalmology, University of Dresden, Dresden, Germany. The lecture was ended with a short training session to use this systematic approach on 15 ONH photographs; nine glaucomatous ONHs, four healthy ONHs, one ONH with drusen and one ONH with optic pit.
Results
Ninety-six doctors, 91% of all attending the meeting, completed both assessment sessions. The largest group, 39% of all participants, consisted of ophthalmologists with special interest in glaucoma, the second largest, 29%, was general ophthalmologists, 16% reported themselves to be glaucoma specialist, 3% other subspecialty and 7% were residents. The remaining 6% percent of the 96 participants did not report any group affiliation. The majority, 80%, of the participating doctors stated themselves to be very experienced or experienced in glaucoma care, and 77% had been active as clinicians for at least 10 years.
The number of correct classifications increased from 69 to 72% on the average. Diagnostic sensitivity increased significantly (p < 0.0001) from 70% to 80%, and the number of photographs classified as uncertain decreased significantly (p < 0.0001) from 22% to 13%.
Discussion
The effect of re-training of ONH assessment showed improved sensitivity and the number of uncertain classifications decreased, while specificity remained at the same level.
Uncertain classifications in the group with all graders, decreased significantly in number after the training session. A decrease was seen for all the subgroups, and somewhat surprisingly, even the glaucoma experts showed a marked decrease in the amount of uncertain classifications. The move from the uncertain alternative in the first session was almost equally divided to the glaucoma and healthy alternatives in the second session.
The authors recognized that the current study was the first to investigate the effect of CME for the glaucoma diagnosis in ophthalmologists with different experience. This kind of CME is often offered at ophthalmic meetings, with the aim of improving diagnostic performance of the auditorium. In this study both sensitivity and specificity improved significantly with 10 to 20% in the two groups. In the current study sensitivity, but not specificity, improved after the lecture.
Conclusion
Ultimately, the authors concluded that the CME program increased sensitivity and the amount of uncertain classifications decreased.