By Alma I. Murphy, MD
This retrospective, longitudinal cohort analysis in the April issue of Ophthalmology assessed trends in the use of ancillary diagnostic tests to evaluate patients with open-angle glaucoma (OAG) and glaucoma suspects in a managed care network. The authors found that use of ocular imaging other than traditional visual field (VF) testing and fundus photography (FP) increased dramatically from 2001 to 2009, whereas VF testing declined considerably. They conclude that since other ocular imaging (OOI) has not been shown to be as effective at detecting OAG or disease progression compared with VF testing, increased reliance on OOI may be detrimental to patient care.
Over the past decade, OOI devices beyond FP have assisted eye care providers in managing patients with OAG and suspected glaucoma. Confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography have been promoted for detecting structural damage to the optic nerve and retinal nerve fiber layer. However, it is unclear how well they detect glaucoma progression. OOI devices have been found to have moderate sensitivity at best, ranging from 68 to 91 percent, and specificity of 80 to 97 percent for detecting OAG.
In the current study, the authors analyzed claims data for 169,917 individuals with OAG and 395,271 individuals with suspected glaucoma. Among OAG patients, the odds of undergoing VF testing decreased by 36 percent from 2001 to 2005, 12 percent from 2005 to 2009 and a total of 44 percent from 2001 to 2009. In contrast, the odds of undergoing OOI increased by 100 percent from 2001 to 2005, 24 percent from 2005 to 2009 and by a total of 147 percent from 2001 to 2009. The probability of undergoing FP was relatively low, at 13 to 25 percent, and remained stable over the decade for both provider types.
Among patients cared for exclusively by optometrists, the probability of VF testing decreased from 66 percent in 2001 to 44 percent in 2009. Among those seen exclusively by ophthalmologists, the probability of VF testing decreased from 65 percent in 2001 to 51 percent in 2009. By 2008, OAG patients receiving care exclusively from optometrists had a higher probability of undergoing OOI than VF testing.
The authors say these findings suggest that greater efforts should be made to educate ophthalmologic and optometric trainees about the importance of VF testing in glaucoma management.
They add that if future studies confirm this study's findings of a shift in eye care providers' methods for following OAG and suspected glaucoma, greater attention should be paid to more fully understanding and overcoming some of the limitations of OOI devices. They say it is essential that some of the newer software products aimed at detecting disease progression with these devices undergo adequate internal and external validation, and that manufacturers address issues of noncompatibility between results generated with older and newer models so that patients' disease progression can be carefully followed over time.
They conclude that until these newer imaging devices demonstrate better ability to identify the presence of glaucoma and more fully capture disease progression compared with more traditional equipment, they should be used, if at all, only as an adjunct to and not a replacement for perimetry and FP.