Comparison of two reference standards in validating two field mydriatic digital photography as a method of screening for diabetic retinopathy

AIM: To compare two reference standards when evaluating a method of screening for referable diabetic retinopathy. METHOD: Clinics at Oxford and Norwich Hospitals were used in a two centre prospective study of 239 people with diabetes receiving an ophthalmologist's examination using slit lamp biomicroscopy, seven field 35 mm stereophotography and two field mydriatic digital photography. Patients were selected from those attending clinics when the ophthalmologist and ophthalmic photographer were able to attend. The main outcome measures were the detection of referable diabetic retinopathy as defined by the Gloucestershire adaptation of the European Working Party guidelines. RESULTS: In comparison with seven field stereophotography, the ophthalmologist's examination gave a sensitivity of 87.4% (confidence interval 83.5 to 91.5), a specificity of 94.9% (91.5 to 98.3), and a kappa statistic of 0.80. Two field mydriatic digital photography gave a sensitivity of 80.2% (75.2 to 85.2), specificity of 96.2% (93.2 to 99.2), and a kappa statistic of 0.73. In comparison with the ophthalmologist's examination, two field mydriatic digital photography gave a sensitivity of 82.8% (78.0 to 87.6), specificity of 92.9% (89.6 to 96.2), and a kappa statistic of 0.76. Seven field stereo gave a sensitivity of 96.4% (94.0 to 98.8), a specificity of 82.9% (77.4 to 88.4), and a kappa statistic of 0.80. 15.3% of seven field sets, 1.5% of the two field digital photographs, and none of the ophthalmologist's examinations were ungradeable. CONCLUSION: An ophthalmologist's examination compares favourably with seven field stereophotography, and two field digital photography performs well against both reference standards.     

Comparison of stereoscopic digital imaging and slide film photography in the identification of macular degeneration

BACKGROUND: This study compared the sensitivity and specificity of stereoscopic digital photography of the retina through a dilated pupil with a 45 degrees nonmydriatic camera and Joint Photographic Experts Group (JPEG) compression of the images with the sensitivity and specificity of 35-mm slide film photography in the identification of age-related macular degeneration (AMD). METHODS: Consecutive patients with a diagnosis of AMD were enrolled. Stereoscopic retinal images of the disc, macula and temporal macula were captured with a digital 45 degrees nonmydriatic camera (then compressed into JPEG format) and with a standard fundus camera and slide film. A single retinal specialist graded both image formats in masked fashion, at least 1 month apart, using a modified Age-Related Eye Disease Study (AREDS) severity scale. The digital images were displayed on a monitor and viewed with the use of liquid crystal display shutter glasses and stereo imaging software. The film images were mounted on a light box and graded with the use of a stereoviewer. Primary outcome measures included the presence or absence of AMD pathological features. Positive and negative predictive values (PPVs and NPVs), sensitivity, specificity and weighted kappaw statistics were calculated. RESULTS: We photographed 203 eyes (of 103 patients) with both digital and slide film cameras. Correlation of the 2 image formats was substantial in identifying AREDS level 3a or greater (kappaw=0.64, standard error=0.08, PPV=0.95, NPV=0.66, sensitivity=0.93, specificity=0.74) and excellent in identifying level 4b or greater (kappaw=0.83, standard error=0.05, PPV=0.81, NPV=0.98, sensitivity=0.94, specificity=0.94). INTERPRETATION: High-resolution stereoscopic, mydriatic, 45 degrees digital images captured with a nonmydriatic camera and JPEG compressed correlate well with stereoscopic slide film photographs in the identification of moderate to advanced AMD (AREDS level 3a or greater).     

Can we predict which patients are at risk of having an ungradeable digital image for screening for diabetic retinopathy?

PURPOSE: We aimed to determine the reasons for, and variables which predicted, ungradeable retinal photographs during screening patients for diabetic retinopathy.MATERIALS AND METHODS: Age, duration of diabetes, visual acuity, and HbA1c were recorded. Following dark adaptation, a single 45 degrees nonmydriatic photograph was taken of each fundus. The pupils were then dilated and the photograph repeated. Using slit lamp biomicroscopy, lenticular changes (LOCS III), and fundus appearance were recorded.RESULTS: In ungradeable photographs the fovea could not be visualised in 98% of cases of images from nonmydriatic photography, and in 88% if mydriasis was used. Poor definition in the nonmydriatic image was associated with a subsequent ungradeable mydriatic photograph (P=0.001), however, the positive predictive value was poor (34%). Age, posterior subcapsular cataract, and near vision predicted ungradeable status of nonmydriatic photographs (P<0.001, P=0.004, P=0.006, respectively; regression analysis). Nuclear colour and poor definition of the nonmydriatic photograph predicted ungradeable status of mydriatic photographs (P=0.006 & P=0.001, respectively).CONCLUSION: Inability to visualise the fovea is the commonest cause of an ungradeable image from digital retinal photography. Age and posterior subcapsular cataract were best predictors of ungradeable status of nonmydriatic fundus photographs. Nuclear colour was the strongest predictor for ungradeable mydriatic photography.     

Stereo nonmydriatic digital-video color retinal imaging compared with Early Treatment Diabetic Retinopathy Study seven standard field 35-mm stereo color photos for determining level of diabetic retinopathy

OBJECTIVE: To evaluate the ability to determine clinical levels of diabetic retinopathy, timing of next appropriate retinal evaluation, and necessity of referral to ophthalmology specialists using stereoscopic nonmydriatic digital-video color retinal images as compared with Early Treatment Diabetic Retinopathy Study (ETDRS) seven standard field 35-mm stereoscopic color fundus photographs. DESIGN: Prospective, clinic-based, comparative instrument validation study. PARTICIPANTS: Fifty-four patients (108 eyes) with type 1 or type 2 diabetes mellitus selected after chart review from a single center to include the full spectrum of diabetic retinopathy. METHODS: Nonsimultaneous 45 degrees -field stereoscopic digital-video color images (JVN images) were obtained from three fields with the Joslin Vision Network (JVN) system before pupil dilation. Following pupil dilation, ETDRS seven standard field 35-mm stereoscopic color 30 degrees fundus photographs (ETDRS photos) were obtained. Joslin Vision Network images and ETDRS photos were graded on a lesion-by-lesion basis by two independent, masked readers to assess ETDRS clinical level of diabetic retinopathy. An independent ophthalmology retina specialist adjudicated interreader disagreements in a masked fashion. MAIN OUTCOME MEASURES: Determination of ETDRS clinical level of diabetic retinopathy, timing of next ophthalmic evaluation of diabetic retinopathy, and need for prompt referral to ophthalmology specialist. RESULTS: There was substantial agreement (kappa = 0.65) between the clinical level of diabetic retinopathy assessed from the undilated JVN images and the dilated ETDRS photos. Agreement was excellent (kappa = 0.87) for suggested referral to ophthalmology specialists for eye examinations. Comparison of individual lesions between the JVN images and the ETDRS photos and for interreader comparisons were comparable to the prior ETDRS study. CONCLUSIONS: Undilated digital-video images using the JVN system were comparable photographs for the determination of diabetic retinopathy level. The results validate the agreement between nonmydriatic JVN images and dilated ETDRS photographs and suggest that this digital technique may be an effective telemedicine tool for remotely determining the level of diabetic retinopathy, suggesting timing of next retinal evaluation and identifying the need for prompt referral to ophthalmology specialists. Thus, the JVN system would be an appropriate tool for facilitating increased access of diabetic patients into recommended eye evaluations, but should not be construed as a paradigm that would replace the need for comprehensive eye examinations.     

Assessing diabetic retinopathy using two-field digital photography and the influence of JPEG-compression

Objective: To study the effectiveness of two digital 50° photographic fields per eye, stored compressed or integrally, in the grading of diabetic retinopathy, in comparison to 35-mm colour slides. Subjects and methods: Two-field digital non-stereoscopic retinal photographs and two-field 35-mm retinal photographs were made at the same time from patients visiting a diabetic retinopathy outpatient clinic. The digital images were stored integrally (TIFF-file) and in a compressed way (JPEG-file). Two ophthalmologists assessed the photographs in a masked fashion. The results were compared. The sensitivity and specificity for the detection of vision-threatening diabetic retinopathy were calculated, using only the grading of the most affected eye. The differences between the retinopathy gradings of the two kinds of photographs were analysed. Results: The agreement for the grading of DR compared to slides was good, both for the compressed and for the integrally stored images (kappa 0.63–0.68). The sensitivity for the detection of vision-threatening diabetic retinopathy using the JPEG-stored images was 0.72–0.74, specificity 0.93–0.98. The sensitivity for vision-threatening retinopathy detection using the integrally stored images was 0.86–0.92, specificity 0.93. Conclusions: Two-field digital retinal photography is effective in diabetic retinopathy grading and it can replace 35-mm retinal photography. Vision-threatening retinopathy can be detected on the images with reasonable to good sensitivity and specificity. An experienced grader should assess the images. The compression of the digital images seems to have some adverse effect on the detection of diabetic retinopathy.     

Effectiveness and safety of screening for diabetic retinopathy with two nonmydriatic digital images compared with the seven standard stereoscopic photographic fields

BACKGROUND: The use of nonmydriatic cameras, which offer ease of screening and 45 degrees immediate imaging of the fundus, is gaining increasing acceptance for screening programs tailored to diverse conditions. We performed a study to evaluate the effectiveness and safety of screening for diabetic retinopathy with two nonmydriatic camera images compared with the seven standard stereoscopic 30 degrees fields (7SF). We also wished to determine whether safe screening guidelines could be established to identify patients needing referral to an ophthalmologist. METHODS: In this prospective masked cross-sectional study, we evaluated agreement in the assessment of the severity of diabetic retinopathy by means of two 45 degrees images centred on the optic disc and on the macula obtained with the Topcon CRW6 nonmydriatic camera and by means of 7SF photography and ophthalmologic slit-lamp biomicroscopy, both performed with pupil dilation. Between November 2000 and June 2001, 98 adult patients known to have type 1 or 2 diabetes mellitus who presented for the first time to the diabetic retinopathy clinic of a tertiary care centre in Montreal were enrolled consecutively. Thus, patient recruitment was weighted toward more severe retinopathy to ensure sufficient representation of less frequent but more severe levels. Each patient underwent nonmydriatic fundus photography of both eyes, followed by a complete ophthalmologic examination with pupil dilation by a single retina specialist and 7SF photography of both eyes with pupil dilation. The level of retinopathy was graded independently in each eye from the 7SF photographs according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale by two graders; an independent retina specialist adjudicated the rare instances of interreader disagreement in a masked fashion. Two months later, two graders independently graded the nonmydriatic images in a blinded fashion according to the ETDRS scale; a third observer adjudicated the rare instances of interreader disagreement. We measured concordance between grading results with the various screening techniques using the weighted and unweighted kappa statistic. We used sensitivity and specificity indices to determine safe screening guidelines to identify patients needing referral to an ophthalmologist. RESULTS: There was substantial agreement in the grading of retinopathy with nonmydriatic camera imaging and with 7SF photography, both for all eyes (kappa = 0.626 [standard deviation (SD) 0.045]) and for the eye with more severe disease (kappa = 0.654 [SD 0.063]). With nonmydriatic camera imaging, screening thresholds for patient referral to an ophthalmologist of very mild retinopathy (ETDRS grade 20), mild retinopathy (ETDRS grade 35) and moderate retinopathy (EDTRS grade 43) had sensitivity values of 97.9%, 97.1% and 53.3% respectively and specificity values of 81.3%, 95.5% and 96.9% respectively. Screening thresholds of very mild or mild retinopathy both correctly identified 100% of eyes with severe nonproliferative or proliferative retinopathy. With a screening threshold of mild retinopathy, screening with the nonmydriatic camera would lead to referral to an ophthalmologist of 37.8% of patients because of detected disease and of an additional 17.3% because of insufficient image quality in at least one eye, for a total of 55.1%. The overall sensitivity and specificity of a two-field nonmydriatic screening strategy with a threshold of mild retinopathy for referral of patients with insufficient image quality in at least one eye are 97.7% and 84.0% respectively. INTERPRETATION: Our results suggest that two-field nonmydriatic camera imaging is a safe screening strategy that may identify the patients with diabetes most in need of ophthalmologic care.     

Single-field fundus photography for diabetic retinopathy screening: a report by the American Academy of Ophthalmology

OBJECTIVE: To evaluate whether single-field fundus photography can be used as a screening tool to identify diabetic retinopathy for referral for further ophthalmic care. METHODS: A MEDLINE search of the peer-reviewed literature was conducted in June 2001 for the years 1968 to 2001 and updated in September 2003, yielding 145 articles. The search was limited to articles published in English. The Cochrane Library of clinical trials was also investigated. The authors reviewed the abstracts of these articles and selected 63 of possible clinical relevance for review by the panel. Of these 63 articles, the panel selected 32 for the panel methodologist to review and rate according to the strength of evidence. RESULTS: Three of the 32 articles reviewed were classified as level I evidence, and 4 were classified as level II evidence. Evidence from level I studies demonstrates that as a tool to detect vision-threatening retinopathy, single-field fundus photography interpreted by trained readers has sensitivity ranging from 61% to 90% and specificity ranging from 85% to 97% when compared with the gold standard reference of stereophotographs of 7 standard fields. When compared with dilated ophthalmoscopy by an ophthalmologist, single-field fundus photography has sensitivity ranging from 38% to 100% and specificity ranging from 75% to 100%. CONCLUSIONS: Single-field fundus photography is not a substitute for a comprehensive ophthalmic examination, but there is level I evidence that it can serve as a screening tool for diabetic retinopathy to identify patients with retinopathy for referral for ophthalmic evaluation and management. The advantages of single-field fundus photography interpreted by trained readers are ease of use (only one photograph is required), convenience, and ability to detect retinopathy. Further studies will be required to assess the implementation of single-field photography-based programs to confirm the clinical and cost-effectiveness of these techniques in improving population visual outcomes. Future research also should include establishing standardized protocols and satisfactory performance standards for diabetic retinopathy screening programs.     

单视野免散瞳数码眼底照相筛查糖尿病视网膜病变的敏感性和特异性

目的:单视野免散瞳眼底照相和散瞳直接眼底镜检查与荧光素眼底血管造影(fundus fluorescein angiography,FFA)相比较,评价其筛查糖尿病视网膜病变(diabetic retinopathy,DR)的敏感性和特异性。方法:1型或2型糖尿病患者93例186眼,先后进行单视野免散瞳数码眼底照相、散瞳直接眼底镜检查和FFA,以FFA诊断结果作为比较标准,评价单视野免散瞳数码眼底照相和散瞳直接眼底镜筛查DR的敏感性和特异性。结果:单视野免散瞳数码眼底照相检出DR的敏感性和特异性分别为80.4%和94.7%,而散瞳直接眼底镜检出DR的敏感性和特异性分别为64.2%和84.2%。当把筛查阈值下调至中度非增殖性DR(M-NPDR)后,单视野免散瞳数码眼底照相检出DR的敏感性和特异性分别提高为88.9%和98.4%,散瞳直接眼底镜检出DR的敏感性和特异性也均有提高,分别为71.5%和96.7%。结论:单视野免散瞳数码眼底照相是筛查DR的有效工具。     

七方位彩色眼底照像法对糖尿病视网膜病变的诊断价值

目的 筛选经济、简便、有效地糖尿病视网膜病变检查法.方法 分别采用散瞳50度眼底后极部彩色照像法、美国早期糖尿病性视网膜病变治疗研究小组确立的散瞳30度眼底七方位彩色照像法和FFA法对164例(308只眼)糖尿病患者进行检查,由有经验的眼底医生按照糖尿病视网膜病变国际临床分类法对图片进行分析给出分期,对三种方法所得结果进行比较.结果 散瞳50度眼底后极部彩色照像法和FFA法在DR诊断分期中一致性一般(k=0.488),七方位彩色眼底照像法和FFA法在DR诊断分期中有比较好的一致性(k=0.873).结论 七方位彩色眼底照像法可作为糖尿病视网膜病变筛查和指导治疗的一种比较可靠的方法,而散瞳50度眼底后极部彩色照像法的可靠性一般.     

A comparison between one- and two-field 60 degree fundus photography when screening for diabetic retinopathy

PURPOSE: To compare the severity level of diabetic retinopathy obtained when assessed from two versus only one 60 degrees photographic field using colour transparencies and red-free, black-and-white photographs. To compare the areal coverage of these two photographic strategies to that of seven-field 30 degrees photography. METHODS: Two ophthalmologists graded photographs of 74 eyes of 74 type I and II diabetes patients. Inter-method agreement was expressed in percentages and using kappa statistics and scatter-diagrams. The comparison of the approximate photographic areal coverage was done from diagrams using planimetry. RESULTS: The severity level of retinopathy when judged from two photographic fields was more severe in 13.5% (Grader 1) and in 16.2% (Grader 2) from colour transparencies and in 13.5% (Grader 1) and in 14.9% (Grader 2) from red-free black-and-white prints, as compared to assessments from only one field. Kappa values (0.84-0.86) for inter-method agreement for five pooled retinopathy levels revealed good agreement. Neither grader missed retinopathy requiring clinical assessment or treatment (levels > or = 47) when minimal retinopathy (levels 14-20) was detected using only one 60 degrees colour slide or red-free photograph. A second optic disc-centred field provided valuable additional information when more severe retinopathy lesions (levels > or = 30) were detected in the macula-centred field. One macula-centred 60 degrees photograph covered 60% and two 60 degrees photographs 80% of the area covered by seven-field 30 degrees photography. Two-field 60 degrees photography covers areas left outside seven-field 30 degrees photography. CONCLUSION: We propose the use of one macula-centred 60 degrees photograph when screening for the first lesions of diabetic retinopathy. After they have been found two-field 60 degrees photography is recommended.     

Diabetic retinopathy as detected using ophthalmoscopy, a nonmydriatic camera and a standard fundus camera

The study was performed to evaluate whether the severity of diabetic retinopathy as assessed by three alternative methods was concordant with the severity of retinopathy as determined from 30 degrees stereoscopic photographs. The three methods were direct ophthalmoscopy through an undilated pupil, nonstereoscopic 45 degrees retinal photography through a pharmacologically undilated pupil and nonstereoscopic 45 degrees photography through a dilated pupil. A single 45 degrees photograph centered between the disc and fovea was taken and direct ophthalmoscopy was performed on 99 persons prior to pharmacological dilation of the pupil. After dilation, another 45 degrees photograph was taken of the same field, as well as 30 degrees stereoscopic color photographs of DRS fields 1, 2 and 4 (modified). Corresponding photographic fields were graded by masked, trained graders for the severity of retinopathy and for the presence of specified diabetic lesions using the Modified Airlie House Classification scheme. For three levels of severity of retinopathy (none, nonproliferative or proliferative) exact agreement between direct ophthalmoscopy and grading of retinopathy from stereoscopic photographs taken with the standard 30 degrees camera was 54.3% (n = 94). For four levels of severity of retinopathy (none, microaneurysms only, all other nonproliferative retinopathy and proliferative retinopathy), exact agreement between gradings of retinopathy of the 45 degrees photographs taken through undilated pupils and 30 degrees photographs taken through dilated pupils was 82.5% (n = 63); and for 45 degrees photographs and 30 degrees photographs taken through dilated pupils it was 86.5% (n = 74). These data suggest that 45 degrees nonstereoscopic fundus photographs, when graded according to a standard classification scheme, provide reasonably reliable photographic representation of the severity of retinopathy when broad overall categories are used.     

A pilot study to detect glaucoma with confocal scanning laser ophthalmoscopy compared with nonmydriatic stereoscopic photography in a community health screening

PURPOSE: To assess the efficacy and practical usefulness of the Heidelberg Retina Tomograph II (HRT II) compared with nonmydriatic stereoscopic photography in a public glaucoma screening. METHODS: We examined 1173 local residents, aged 40 years or older, who visited a community health screening in Komatsu City. Initial glaucoma screening consisted of noncontact pneumotonometry, nonmydriatic stereoscopic fundus photography, and HRT II. When glaucoma was suspected, the subjects were referred for a definitive examination, in which slit-lamp biomicroscopic examination, Goldmann applanation tonometry, Humphrey 30-2 test, gonioscopy, and optic nerve head evaluation were performed. RESULTS: A total of 97.2% (2279/2345) of the nonmydriatic stereoscopic optic disc photographs could be interpreted and 93.4% (2189/2345) were good images. HRT II measurements were successful in 99.0% (2322/2345) of eyes, and acceptable images were obtained in 91.9% (2154/2345) of eyes. On the basis of clinical diagnoses, 94 eyes of 60 participants were diagnosed with glaucoma. The sensitivity of nonmydriatic stereoscopic photographs for personal-level analysis and eye-level analysis was 95.8% and 95.5%, respectively. Using Moorfield's regression analysis, HRT sensitivity and specificity were 72.3% to 91.5% and 84.0% to 93.1%, respectively, for personal-level analysis, and 60.3% to 72.6% and 89.7% to 95.6%, respectively, for eye-level analysis. CONCLUSION: Although HRT II did not detect glaucoma as well as optic nerve stereophotographs in this Japanese population, it may play a role in community health screening.     

Screening for diabetic retinopathy using a digital non-mydriatic camera compared with standard 35-mm stereo colour transparencies

PURPOSE: To investigate the use of a digital non-mydriatic camera for determining the ETDRS clinical level of diabetic retinopathy, and to evaluate its use in a screening setting to appropriately determine the need for referral to an ophthalmologist (ETDRS level > or = 35). METHODS: A total of 83 patients with diabetes were photographed with and without pharmacological pupil dilation at an ophthalmology department using a digital non-mydriatic camera, obtaining two sets of five non-stereoscopic, 45 degree field images of each eye. ETDRS seven standard field, 35-mm stereoscopic colour fundus photographs were also obtained. A subgroup of 59 patients was photographed at an optician's shop using the digital non-mydriatic camera without pupil dilation. RESULTS: There was substantial agreement between the clinical level of diabetic retinopathy assessed from the 35-mm photographs and the digital images: the ophthalmology department (kappa = 0.76) with pupil dilation and (kappa = 0.66) without pupil dilation, respectively, and at the optician's (kappa = 0.60 without pupil dilation). With respect to the need for referral to an ophthalmologist, there was almost perfect agreement in the ophthalmology department (kappa = 0.88) with pupil dilation and (kappa = 0.84) without pupil dilation, respectively, and those taken at the optician's (kappa = 0.87 without pupil dilation). CONCLUSION: A digital non-mydriatic camera may be used in a screening situation to appropriately determine the need for referral to an ophthalmologist (ETDRS level > or = 35).     

免散瞳眼底照相技术在糖尿病视网膜病变筛查中的应用研究

目的:评估免散瞳眼底照相技术与直接眼底镜检查作为糖尿病视网膜病变(diabetic retinopathy,DR)筛查方法时与金标准荧光造影的比较性研究,并将比较后的数据统计分析,计算每种方法的敏感度、特异度、KAPPA值以筛选出快捷、高效的DR筛查方法。方法:对54例(105眼)在我院门诊就诊或住院的2型糖尿病(T2DM)患者,进行散瞳直接眼底镜检查、免散瞳眼底照相及眼底荧光造影检查,而后分别对直接眼底镜检查和眼底荧光造影、免散瞳眼底照相和眼底荧光造影检查的结果统计分析。结果:在检出DR的结果中,直接眼底镜检查和免散瞳眼底照相的敏感度分别是63.4%、86.8%,特异度分别是76.9%、92.3%,Youden指数分别是41.1%、79.1%,卡帕检验的一致性分别是41.9%、80.7%。在检出有高度视力丧失危险的DR结果中,直接眼底镜检查和免散瞳眼底照相的敏感性分别是65.5%、93.1%,特异性分别是94.7%、97.4%,Youden指数分别是60.3%、90.5%,卡帕检验的一致性分别是39.1%、61.2%。结论:对于检出DR及检出有高度视力丧失危险的DR病变,免散瞳眼底照相较直接眼底镜检查有更高的敏感性、特异性并卡帕检验的一致性好,结合临床考虑,认为免散瞳眼底照相技术可以作为DR的一种优化的筛查方法。     

Comparison of two, three and four 45 degrees image fields obtained with the Topcon CRW6 nonmydriatic camera for screening for diabetic retinopathy

BACKGROUND: The use of the nonmydriatic camera is gaining increasing acceptance for the detection of diabetic retinopathy when integrated into a community-tailored program. We performed a study to evaluate the optimal number and positioning of photographic fields necessary to screen for diabetic retinopathy with the Topcon CRW6 nonmydriatic camera. METHODS: In this prospective masked cross-sectional comparative study, we compared the assessment of diabetic retinopathy using two, three or four 45 degrees fundus images (centred respectively on the disc and the macula; on the disc, on the macula and temporal to the macula; and on the disc, on the macula, temporal to the macula and superotemporal to the macula, including the superior temporal vein) acquired with the Topcon CRW6 nonmydriatic camera, with the grading of the seven standard stereoscopic 30 degrees field photographs (7SF). The study population consisted of 98 consecutive adult patients known to have type 1 or 2 diabetes mellitus who presented for the first time to the diabetic retinopathy clinic of a tertiary care centre in Montreal. All patients underwent four nonmydriatic fundus photography sessions of both eyes, 7SF photography with pupil dilation and a complete ophthalmologic examination with pupil dilation by a retina specialist. RESULTS: Compared to the 7SF, the sensitivity and specificity of screening for any retinopathy (Early Treatment Diabetic Retinopathy Study [ETDRS] grade greater than 10) using the two central fields were 95.7% and 78.1% respectively. The corresponding values with three image fields were 97.6% and 71.9%, and with four image fields, 97.6% and 65.6%. The sensitivity and specificity of screening for mild or worse disease (ETDRS grade 35 or greater) using the two central fields were 87.5% and 92.3%. The corresponding values with three image fields were 88.9% and 94.6%, and with four image fields, 88.9% and 91.9%. Poor image quality occurring with the addition of extra fields resulted in an increase of 6.2% in the rate of referral to an ophthalmologist. The use of two image fields missed no cases of retinopathy. INTERPRETATION: The use of image fields in addition to the two 45 degrees images centred on the disc and the macula on imaging with the Topcon CRW6 nonmydriatic camera did not significantly increase the sensitivity or specificity of screening for diabetic retinopathy. Contrary to the desired effect, the addition of fields resulted in diminished utility and cost-effectiveness of this screening approach.     

Comparison of a digital retinal imaging system and seven-field stereo color fundus photography to detect diabetic retinopathy in the primary care environment.

BACKGROUND AND OBJECTIVE: Because patients with diabetes mellitus may visit their primary care physician regularly but not their ophthalmologist, a retinal risk assessment in the primary care setting could improve the screening rate for diabetic retinopathy. An imaging system for use in the primary care setting to identify diabetic retinopathy requiring referral to an ophthalmologist was evaluated. PATIENTS AND METHODS: In a masked prospective study, images were obtained from 11 patients with diabetes mellitus using both the digital retinal imaging system and seven-field stereo color fundus photography. The ability to obtain gradable images and to identify diabetic retinal lesions was compared. RESULTS: Of all images, 85% of digital retinal imaging system images and 88% of seven-field images were gradable. Agreement based on "no retinopathy" versus "any retinopathy" was excellent (Kappa = 0.96). Agreement based on "microaneurysms or less retinopathy" versus "retinal hemorrhages or worse retinopathy" was very good (Kappa = 0.83). CONCLUSIONS: The agreement between the digital retinal imaging system and seven-field photography indicates that the digital retinal imaging system may be useful to screen for diabetic retinopathy.     

Screening for diabetic retinopathy by one-field, non-mydriatic, 45 degrees digital photography is inadequate

PURPOSE: To evaluate the sensitivity and specificity of one-field, non-mydriatic, 45 degrees digital photography for screening for diabetic retinopathy compared to indirect ophthalmoscopy using a slit-lamp, the reference standard. METHODS: A total of 100 consecutive diabetic patients (200 eyes) who underwent digital fundus photography and ocular examinations from June 2002 to November 2002 were included in this retrospective study. The patients, recruited from a hospital-based, retina referral practice, underwent 45 degrees, non-mydriatic, digital fundus photography using a non-mydriatic fundus camera. One image was obtained focusing the mid fundus between the optic disc and the macula. The fundus images were printed and graded by endocrinologists and a retinal specialist separately. The patients also underwent complete standard ocular examinations as the reference method for determining diabetic retinopathy, including dilation of their pupils and slit-lamp biomicroscopy done by ophthalmologists. The sensitivity and specificity of the digital photographic method were calculated by comparison to the reference method. RESULTS: The sensitivity and specificity of the retinal specialist's diabetic retinopathy grades were 53.8 and 89.0%, respectively. The sensitivity and specificity of the endocrinologists' grades were 45 and 75.3%, respectively. The false negative rates were 22 and 21.5% for endocrinologists and the retinal specialist, respectively. CONCLUSIONS: Screening for diabetic retinopathy using one-field, non-mydriatic, 45 degrees digital photography is inadequate.     

Comparison between ophthalmoscopy and fundus photography in determining severity of diabetic retinopathy

Diabetic retinopathy was assessed in a population-based study of 2708 diabetic persons in southern Wisconsin. The retinopathy levels as determined by ophthalmoscopy and by the grading of stereoscopic fundus photographs were compared in the eyes of 1949 persons. Ophthalmoscopy was performed by an ophthalmologist and a specially trained optometrist and ophthalmic technician. Consultation among the three examiners was permitted. There was exact agreement between ophthalmoscopy and grading for detecting retinopathy (none, nonproliferative, proliferative) 85.7% of the time. The kappa statistic, which corrects for chance agreement, was 0.749. There were no significant differences among the three ophthalmoscopists. Ophthalmoscopy was more likely to disagree with fundus photography grading in eyes with less severe forms of retinopathy and in patients examined early in the study. Other factors found to influence the degree of agreement were age, visual acuity, and duration of diabetes. It is concluded that with proper training ophthalmoscopy can be an acceptable alternative to fundus photography in certain situations.     

Telemedicine approach to screening for severe retinopathy of prematurity: a pilot study

PURPOSE: To evaluate the use of remote reading of digital retinal photographs in the diagnosis of severe (referral-warranted) retinopathy of prematurity (ROP) during longitudinal screening for ROP. STUDY DESIGN: Prospective, longitudinal cohort study. SUBJECTS: Forty-four consecutive premature infants at risk for ROP. METHODS: All infants were examined longitudinally, over a series of examinations, by indirect ophthalmoscopy (gold standard) and digital photography using the RetCam-120 Digital Retinal Camera (Massie Research Laboratories Inc., Dublin, CA) equipped with an ROP lens. Images were stored and read remotely by a masked reader. Referral-warranted ROP was defined as ROP in zone 1, the presence of plus disease or the presence of any stage 3 ROP. We determined whether and when referral-warranted ROP was diagnosed for each eye, of each infant, on each examination, during the course of each of the infant's screening. RESULTS: Severe (referral-warranted) ROP was diagnosed in 23 eyes by indirect ophthalmoscopy during their series of examinations. Digital photography had a sensitivity of 100% and a specificity of 96% in detecting referral-warranted ROP. The positive predictive value of digital photography was 92%, and the negative predictive value was 100%. In 87% of eyes, referral-warranted ROP was diagnosed by digital photography before or at the same time as indirect ophthalmoscopy. CONCLUSIONS: Longitudinal remote reading of digital photographs using the RetCam-120 system has excellent specificity and sensitivity in detecting referral-warranted ROP. This pilot study has shown that remote reading of digital photographs has promise for telemedicine strategies in ROP screening.     

Non-mydriatic fundus photography: A viable alternative to fundoscopy for identification of diabetic retinopathy in an Aboriginal population in rural Western Australia?

Purpose: To evaluate the Canon CR5-45NM non-mydriatic fundus camera (Canon, Kanagawa, Japan) for identifying retinopathy and the need for laser treatment in a population of Aboriginal patients with diabetes mellitus in rural Western Australia.
Methods: Diabetic Aboriginal patients were photographed through undilated pupils using a Canon CR5-45NM nonmydriatic fundus camera, after which ophthalmoscopy was performed using indirect ophthalmoscopy through dilated pupils. The examining ophthalmologist recorded the presence of retinopathy and the need for laser treatment. A proportion of patients were rephotographed through dilated pupils. Photographs were reviewed by a second ophthalmologist who evaluated the quality of the image, the presence of retinopathy and the need for laser treatment. Results of fundus photographs and ophthalmoscopy were compared.
Results: Three hundred and twenty-eight eyes in 164 Aboriginal patients were examined. The mean patient age was 48.2 years (range 16–81 years) and the mean duration of diabetes was 7.5 years (range 1–35 years). Seventy-four eyes (22.6%) were diagnosed with retinopathy using combined examination techniques, 44 (59.5%) of which were identified by ophthalmoscopy and 55 (74.3%) by photography. Thirty-five eyes were deemed to need treatment, 18 (51.4%) of which were identified by ophthalmoscopy and 30 (85.7%) by photography. Kappa coefficient measurement for agreement for presence of retinopathy and need for referral was 0.41 and 0.53, respectively. Photograph quality was significantly improved following pupil dilation.
Conclusions: The Canon CR5-45NM non-mydriatic fundus camera was relatively good at identifying diabetic retinopathy and could usefully be applied within a screening programme for treatable disease within this population.