Preventing overdiagnosis: how to stop harming the healthy

The authors and responders of this article have done a wonderful job in analysing this issue and evoking such wonderful comments to this article which proves that the issue is omnipresent in every field of medicine. But in ophthalmology I have personally seen a unique phenomena with regards to glaucoma over diagnosis causing under diagnosis of other serious neurological conditions . Over diagnosis of glaucoma has been reported to be extremely high, as high as 41% in some cases (1). Many consequences for patients and health care services have been discussed already by some authors (2) Newer more sensitive tests have been implicated and many ways of integrating clinical skills with tests have been suggested (3) The costs of over diagnosis are enormous (4) But one alarming issue that I have encountered is masking of other diseases and the under diagnosis and worsening of other neurological diseases because the patient's anxieties have been managed and field defects have been explained with the diagnosis of glaucoma.

Here the issue noticed by me is that the routine test ordered for visual field is SITA. Standard SITA testing algorithm tends to make all field defects look like glaucomatous field defects due to the manner in which the arcuate areas are tested with priority and assumptions are made in the algorithm due to which in some of our patients visual field defect pathognomic of pituitary tumour or anterior ishaemic optic neuropathy seems to mimick glaucomatous defects in the SITA algorithm in visual field. In a few cases we have had pituitary tumours grow to enormous size while the patient is erroneously using anti glaucoma medications and with progression of field defect an additional drug is instituted instead of review of diagnosis. Many others have lamented that misinterpretation of visual field leads to misdiagnosis and over treatment of glaucoma leading to under diagnosis of neurological conditions and the subsequent visual impairment and morbidity is preventable (5). Some editorials blame the hard selling by pharma companies (6). Nevertheless we have realised that whatever the cause of over diagnosis of glaucoma the issue of under diagnosis of neurological defects is real and not without serious consequences of irreversible visual loss and many a times serious morbidity as well as mortality. So not only do we need to deal with economic costs of over diagnosis but also with under diagnosis of neurological conditions mimicking glaucoma field defects.

1: Zemba M, Cucu B, Stinghe A, Furedi G, Zugravu V, Lacusteanu M. [Overdiagnosis in glaucoma--a real problem?]. Oftalmologia. 2008;52(3):81-6.
2: Detorakis E, Symvoulakis E. Over-diagnosed glaucoma:possible consequences for patients and health care services. Hippokratia. 2011;15(4):381-382.
3: Garway-Heath DF, Friedman DS. How should results from clinical tests be integrated into the diagnostic process? Ophthalmology. 2006 Sep;113(9):1479-80..
4: Vaahtoranta-Lehtonen H, Tuulonen A, Aronen P, Sintonen H, Suoranta L, Kovanen N, Linna M, Läärä E, Malmivaara A. Cost effectiveness and cost utility of an
organized screening programme for glaucoma. Acta Ophthalmol Scand. 2007Aug;85(5):508-18.
5: Choudhari NS, Neog A, Fudnawala V, George R. Cupped disc with normal intraocular pressure: The long road to avoid misdiagnosis. Indian Journal of Ophthalmology. 2011;59(6):491-497. doi:10.4103/0301-4738.86320.
6: Nayak BK, Maskati QB, Parikh R. The unique problem of glaucoma: Under-diagnosis and over-treatment. Indian Journal of Ophthalmology. 2011;59(Suppl1):S1-S2. doi:10.4103/0301-4738.73677.