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Retina Today – The Value of Adding SD-OCT to Nonmydriatic Fundus Photography Screening

• Although scanning laser ophthalmoscopy has advantages over traditional fundus photography for retinal imaging, it does not capture true color information. The patients, recruited from a hospital-based, retina referral practice, underwent 45 degrees, non-mydriatic, digital fundus photography using a non-mydriatic fundus camera. Furthermore, small pupil detection, high sensitivity and low flash intensity are all part of the array of available options within this instrument, making it simpler to produce excellent images and reduce any stress to patient during the scan. Marianne Phillips, IBSC, and Timothy Song, IBSc, are medical students at University College London (UCL). Alternately, retinal photography screening is estimated to cost $61,000. Mydriasis significantly reduced the technical failure rate from 27.1% to 8.3% under a single-field strategy, and from 28.2% to 8.9% under a two-field strategy. The cost of telemedicine-based digital retinal imaging examination included cost for devices, training, annual costs and a transportation fee.

Almost identical results were achieved for both methods with single macular field imaging. An upfront Practice Incentive Program (PIP) payment could offset set up costs. SD-OCT images were obtained as cube sections through the macula and the optic disk, and corresponding fast macular thickness maps and nerve fiber layer analyses were performed. Single 50° field fundus photos were centered on the macula and optic nerve. Two masked graders evaluated all images. They first interpreted the fundus photographs and were then presented with the corresponding SD-OCT data and asked whether it confirmed, was noncontributory to, or refuted their initial diagnosis. The CR3-45NM is relatively cheap and could revolutionise the screening of the diabetic population for DR (Abstract of presentation to the XIIth Congress of the International Diabetes Federation, Madrid, Spain, September 23 – 28, 1985).

Regarding the first aim of the study, to evaluate the feasibility of performing SD-OCT in a primary care setting, adequate images were obtained in 568 of 574 patients (98.9%) patients. Poor scans were attributed to patient movement or to lack of signal intensity due to media opacity. In cases in which the nonmydriatic fundus image was deemed to be of poor quality, SD-OCT could be performed and evaluated in 85.7%. Of the total 568 patients evaluated, SD-OCT findings were normal in both eyes in 516 (90.9%). Vitreomacular adhesion, vitreomacular traction, or abnormal foveal contour was detected in 17 (2.9%), epiretinal membrane (ERM) in 20 (3.5%), drusen in 12 (2.1%), lamellar hole in 2 (0.3%), and cystoid macular edema in 1 (0.2%). Figure 1 shows an example of a patient in whom the fundus photograph appears essentially normal, but a prominent epiretinal membrane is see on the SD-OCT cube scan. Giardini, they looked at ways of using a mobile phone to give a view of the fundus.

Figure 2 shows an example of a patient with what appears to be geographic atrophy, and the SD-OCT confirms the presence of outer retinal atrophy consistent with the diagnosis. Figure 3 shows an example of another patient for whom the SD-OCT refuted the initial diagnosis of retinitis pigmentosa without cystoid edema; the SD-OCT shows clearly that there is significant cystoid edema present. The strengths of this study include its large sample size, its prospective design, and its use of masked graders. More abstractly, crowdsourcing might provide a complement to AI development efforts and computer vision technologies. A recent study has validated that optical coherence tomography results in better detection of retinal pathology than standard nonmydriatic fundus photography.6 The use of SD-OCT in a primary care setting appears to be feasible, as we achieved a 98.9% rate of image acquisition. SD-OCT, used as an adjunct to fundus photography, appears to have some added benefit, confirming the initial diagnosis in the large majority of cases. Overall, we concluded that SD-OCT does provide an additive benefit when evaluating patients in a nonmydriatic screening program.

Uncompressed images were saved on a CD or DVD and submitted to the FPRC according to standard procedures. Still to be answered is the question of whether the incremental gains in information gathered are worth the costs of the machine and additional acquisition time. Rishi P. Singh, MD, is a Staff Member in the Department of Ophthalmology at the Cleveland Clinic. Dr. Singh states that he has served as a consultant to and/or served on the speakers board for Bausch + Lomb, Genentech, Zeiss, Regeneron, and Thrombogenics, and that his institution has received grants from Alcon, Regeneron, and Genentech. He can be reached at drrishisingh@yahoo.com.

Taylor R, Lovelock L, Tunbridge WM, et al. In detecting the absence of diabetic retinopathy, low- or high-risk proliferative diabetic retinopathy, the pooled sensitivity was 80%. BMJ. 1990;301(6763):1243-1247. It is a condition in which the clear lens of the eye becomes cloudy with age, preventing sufficient light rays from entering the eyes and impairing vision. Ophthalmology 1985; 92: 62–7. Am J Ophthalmol.

2002;134(2):204-213. Hansen AB, Hartvig NV, Jensen MS, Borch-Johnsen K, Lund-Andersen H, Larsen M. For the above reasons and as proposed in the algorithm, the authors believe that the combination of VA (which, despite not being a highly sensitive method, is the most economic procedure to suspect its presence) with different simple retinographs (which are available in most hospitals) could provide a degree of detectability achieving sufficient sensitivity to be used as a screening test in the early diagnostic of diabetic macular edema (Fig. Acta Ophthalmol Scand. 2004;82(6):666-672. Tarabishy AB, Campbell JP, Misra-Hebert A, Seballos RJ, Lang RS, Singh RP. Non-mydriatic single-field fundus photography for the screening of retinal diseases in an executive health clinic.

However, if it does not clear up, a vitrectomy may be necessary. 2011;42(2):102-106. Thomas AS, Seballos R, Lang R, Singh RP. Does spectral domain OCT provide any additional useful information to non-mydriatic fundus photography in the screening of asymptomatic patients? Paper presented at: Association for Research in Vision and Ophthalmology Annual Meeting; May 06, 2012; Seattle, WA. Ouyang Y, Heussen FM, Keane PA, Sadda SR, Walsh AC. The retinal disease screening study: prospective comparison of nonmydriatic fundus photography and optical coherence tomography for detection of retinal irregularities.

Invest Ophthalmol Vis Sci. 2013;54(2):1460-1468.

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