et al. reported a prevalence of DR of 40.3% among adult patients in the USA [21]. A few reasons can explain the low prevalence found in the current study. We excluded from the screening protocol described in this chapter patients previously diagnosed with advanced DR, those reporting VA loss, and those whose diabetes was under the care of an endocrinologist because of inadequate glycemic control. Patients with VA loss and inadequate glycemic control are more prone to develop DR. The low prevalence of DR in the group of patients considered suitable for screening by nonmydriatic retinopathy is a reason to justify shifting the screening from ophthalmologists to GPs. A high proportion of patients included in the current protocol will not manifest any sign of DR, and an ophthalmologic assessment would not be justiÞed.

were performed, but this approach is not plausible in other settings.

A signiÞcant progressive decrease was seen in the percentage of unreadable images throughout the study period. This decrease may be the result of improvement by the nurses in their technique of obtaining the retinographies.

Regarding double reading of the retinal images, the recommendations for two readings vary widely [25]. In the current study, 360 patients among the 3,514 whose images initially were diagnosed as normal by the GPs were read again by ophthalmologists, resulting in 10% of the images being read twice. Because the current study was performed during the Þrst 3 years after this model was established, a high percentage of the retinal images was read again to ensure screening reliability, but 5Ð6% of double readings may be adequate [26, 27].

16.5.3 Quality Evaluation

Apart from the sensitivity and speciÞcity and to assess the quality of the screening system, it is important to evaluate the percentages of unreadable images and images read by two examiners. The importance of the percentage of unreadable images is that all of those patients require referral to an ophthalmologist, which reduces the speciÞcity of the screening system. In the UK, less than 5% is recommended [22], and in France, less than 10% [23]. It must be noted that in the UK, screening is performed with mydriasis, while in France the images are obtained without pupil dilation. Screening performed without mydriasis is markedly more comfortable for patients, but the number of referrals increases if the pupils are not dilated [24]. We used an intermediate approach, such that most patients were photographed without mydriasis and only those cases in which the images were considered to be of poor quality by the responsible nurse were dilated with tropicamide to obtain better quality retinographies. Using this system, most patients did not require pupil dilation, and the percentage (2%) of unreadable images was very low. We had the advantage in that some ophthalmologists worked in the same location where the retinographies

16.6Conclusion

With adequate training, GPs can perform highly reliable screening for DR using nonmydriatic retinography. Transferring the screening to GPs in the group of patients with diabetes in the current study releases ophthalmologists from evaluating a high proportion of normal fundi. At the same time, establishing a Þlter for DR screening at the primary care level provides GPs with full control of the diabetic process in uncomplicated patients. This situation facilitates access of patients with diabetes to a screening protocol.

References

1. Fong DS, Aiello L, Gardner TW et al (2003) Diabetic retinopathy. Diabetes Care 26(Suppl 1):S99ÐS102

2.American Diabetes Association (2000) Standards of medical care for patients with diabetes mellitus. Diabetes Care 23(Suppl 1):S32ÐS42

3.Soto-Pedre E, Hernaez-Ortega MC (2008) Screening coverage for diabetic retinopathy using a three-Þeld digital non-mydriatic fundus camera. Prim Care Diabetes 2:141Ð146

4. McKay R, McCarthy CA, Taylor HR (2000) Diabetic retinopathy in Victoria, Australia: the visual impairment project. Br J Ophthalmol 84:865Ð870

5. Massin P, Aubert JP, Aurginay A et al (2004) Screening for diabetic retinopathy: the Þrst telemedical approach in a primary care setting in France. Diabetes Metab 30:451Ð457

6. Lin DY, Blumenkranz MS, Brothers RJ et al (2002) The sensitivity and speciÞcity of single-Þeld nonmydriatic monochromatic digital fundus photography with remote image interpretation for diabetic retinopathy screening: a comparison with ophthalmoscopy and standardized mydriatic color photography. Am J Ophthalmol 134:204Ð213

7. Stellingwerf C, Hardus PL, Hooymans JM (2001) Two-Þeld photography can identify patients with vision-threatening diabetic retinopathy: a screening approach in the primary care setting. Diabetes Care 24:2086Ð2090

8. Massin P, Aubert JP, Eschwege E et al (2005) Evaluation of a screening program for diabetic retinopathy in a primary care setting Dodia (D•pistage ophtalmologique du diab•te) study. Diabetes Metab 31:153Ð162

9.Gomez-Ulla F, Fern‡ndez MI, Gonz‡lez F et al (2002) Digital retinal images and teleophthalmology for detecting and grading diabetic retinopathy. Diabetes Care 25:1384Ð1389

10. Palacios MJ, Monserrat Bagur S, Badia Llach X et al (2003) Non mydriatic retinal camera: cost-effective- ness study for early detection of diabetic retinopathy. Med Clin (Barc) 121:446Ð452 [Spanish]

11. Farley TF, Mandava N, Prall FR et al (2008) Accuracy of primary care clinicians in screening for diabetic retinopathy using single-image retinal photography. Ann Fam Med 6:428Ð434

12. Askew D, Schluter PJ, Spurling G et al (2009) Diabetic retinopathy screening in general practice. A pilot study. Aust Fam Physician 38:650Ð656

13. Andonegui J, Serrano L, Eguzkiza A et al (2010) Diabetic retinopathy screening using tele-ophthalmol- ogy in a primary care setting. J Telemed Telecare 16: 429Ð432

14. Romero P, Sagarra R, Ferrer J et al (2010) The incorporation of family physicians in the assessment of

diabetic retinopathy by non-mydriatic fundus camera. Diabetes Res Clin Pract 88:184Ð188

15. Wilkinson CP, Ferris FL 3rd, Klein RE et al (2003) Proposed international clinical diabetic retinopathy and diabetic macular edema disease severity scales. Ophthalmology 110:1677Ð1682

16.http://www.iheeyecare.org/about.asp. Accessed 28 Mar 2011

17.ftp://medical.nema.org/medical/dicom/2009/. Accessed 28 Mar 2011

18.http://www.clearcanvas.ca. Accessed 28 Mar 2011

19.Taylor R (1996) Practical community screening for diabetic retinopathy using the mobile camera: report of a 12 centre study. Diabet Med 13:946Ð952

20. Gill JM, Cole DM, Lebowitz HM et al (2004) Accuracy of screening for diabetic retinopathy by family physicians. Ann Fam Med 2:218Ð220

21. Kempen JH, OÕColmain BJ, Leske MC et al (2004) The prevalence of diabetic retinopathy among adults in the United States. Arch Ophthalmol 122:552Ð563

22. Garvican L, Scanlon PH (2004) A pilot quality assurance scheme for diabetic retinopathy risk reduction programs. Diabet Med 21:1066Ð1074

23.Recommandations francaises pour le d•spistage de la RD par photographies du fond d`oeil. http://www.sfo. asso.fr. Accessed 14 Mar 2011

24.Baeza M, Orozco-Beltran D, Gil-Guillen VF et al (2009) Screening for sight threatening diabetic retinopathy using non-mydriatic retinal camera in a primary care setting: to dilate or not to dilate? Int J Clin Pract 63:433Ð438

25. Leese GP, Ellis D (2007) Editorial. Diabet Med 24: 579Ð581

26. Pandit T, Taylor R (2002) Quality assurance in screening for sight-threatening diabetic retinopathy. Diabet Med 19:285Ð291

27. Erginay A, Chabouis A, Viens-Bitker C et al (2008) OPHDIAT: quality-assurance programme plan and performance of the network. Diabetes Metab 34: 235Ð242

17.1Retinopathy

of Prematurity (ROP)

17.1.1 Definition

Retinopathy of prematurity (ROP) is a vasoproliferative disease that occurs in the developing neonatal retina. It is associated with risk factors such as low birth weight, young gestational age at birth, and excessive oxygen therapy. Ocular sequelae of ROP include retinal detachment, retinal folds, myopia, glaucoma, cataract, strabismus, and amblyopia [10, 21, 31].

Despite many advances in prevention and management, ROP continues to be a leading cause of treatable pediatric blindness and visual impairment throughout the world [8, 34]. Of the approximately four million infants born in the

C.V.O.C. Ventura, M.D. ( )

The Altino Ventura Foundation, R. da Soledade 170, Boa Vista, Recife-PE 50070-040, Brazil

e-mail: camilaventura@hotmail.com

S.L. Williams, M.D. Department of Ophthalmology,

New England Eye Center, Tufts Medical Center, Box 450, 800 Washington St, Boston,

MA 02111, USA

e-mail: swilliams4@tuftsmedicalcenter.org

M.F. Chiang, M.D. Department of Ophthalmology,

Oregon Health & Science University, 3375 SW Terwilliger Boulevard, Portland, OR 97239, USA

e-mail: chiangm@ohsu.edu

United States each year, roughly 80,000 will be at risk for developing ROP, from which 400–600 infants will develop ROP-related blindness [1, 22]. In most developed countries, ROP accounts for 6–18% of childhood blindness. In middleincome countries in Latin America, Eastern Europe, and Asia, this rate has been found to be 15–35% [9]. It is believed that the higher proportion of ROP-related childhood blindness in mid- dle-income countries results from inadequate resources for ophthalmic screening, as well as improved neonatal survival with insufficient control of known, modifiable risk factors [8, 9].

17.1.2 Classification

Development of an international classification system has permitted standardization of diagnostic criteria for ROP management [13, 35, 36]. ROP is classified according to the location, extent, and severity of disease using several parameters:

•The location of the retinopathy is determined by dividing the retina into three zones, with each zone centered on the optic disc (Fig. 17.1).

•The affected eye is staged according to the most severe ROP present and is determined by the degree of vascular abnormality seen at the boundary between the vascular and avascular retina. Disease ranges from stage 1, which has a thin but defined demarcation line, to stage 5, in which there is total retinal detachment.

•The presence of plus disease (+), an indicator of ROP severity, is defined as a degree of venular dilatation and arteriolar tortuosity of