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Ambulatory photographic screening for diabetic retinopathy in nursing homes.

PURPOSE: To evaluate the feasibility and cost of screening for diabetic eye disease in homebound nursing home residents not attending a systematic screening programme. METHODS: Postal survey identification of residents with diabetes in all nursing homes in Liverpool. An ophthalmologist and nurse performed Bailey-Lovie logmar visual acuity (VA), portable slit-lamp examination, fundus photography, and subjective assessment of ability to cooperate with treatment in a sample of homes. Modified Wisconsin photographic grading was performed. Screen-positive patients were invited to a dedicated assessment clinic. Sight-threatening diabetic eye disease (STED) was defined as any of: moderate preproliferative retinopathy or worse, circinate maculopathy, or exudate within 1 disc diameter of fixation. RESULTS: A total of 54 (78%) nursing homes responded reporting 199/2427 (8.2%) residents with diabetes. Of these, 64/80 (80%) residents in 17 homes were examined: VA possible in 50 (78%); slit-lamp examination in 56 (88%); gradable photographs in at least one eye in 34 (53%); STED in 12 (35%) patients. In all, 35 (70%) patients had Snellen-equivalent VA worse than 6/12 in the better eye, of whom 13 (26%) were worse than 6/60. Of 29 screen positive patients, 12 attended the assessment clinic: one was unable to cooperate outside the home; 11 continue under ophthalmic review, four for previously undetected STED of which one listed for laser photocoagulation. Total cost pound 16,980; cost per screen event pound 60.30. CONCLUSIONS: Systematic eye screening in homebound patients with diabetes detects disease but follow-up and treatment is only feasible in a small proportion and at high cost. Alternative targeted assessment is recommended.

Aged↗

Detection of glaucomatous visual field defect using a screening program of Humphrey Field Analyzer.

To evaluate its clinical efficacy, we report the results of Armaly central field screening test in comparison with those of central 30-2 threshold test of Humphrey Field Analyzer. In 83 cases of normotensives, ocular hypertensives, and glaucoma patients with open-angle or narrow-angle enrolled in this study, a total of 143 eyes were examined. Fifty-four out of 61 patients (88.5%) and 73 out of 81 eyes (90.1%) with visual field defects were detected by the Humphrey Field Analyzer screening test. Eight eyes out of 81(9.9%) with visual field defects detected by the screening test were confirmed as false positive. All points of false positive were solitary, which tended to occur more frequently on superior visual field. A false negative of eight eyes out of 62 (12.9%) detected by the screening test was confirmed by the threshold test, which was more frequent on superior field and shown to be located more peripherally from the fixation point. There was no significant difference in either central sensitivity or age of the false positive and negative.

Adult↗

Effective and accurate screening for diabetic retinopathy using a 60 degree mydriatic fundus camera.

UNLABELLED: OBJECTIVES. To establish whether an experienced endocrinologist could screen accurately for diabetic retinopathy using mydriatic 60 degree fundus photographs compared with a reference standard, viz. the combined highest scores of two experienced ophthalmologists. DESIGN: Retrospective review of 60 degree colour transparency photographs taken over a 6-year period. Retinopathy was graded in a standardised way. SETTING: Patients attending the diabetic clinic at Johannesburg Hospital, South Africa. SUBJECTS: Fifteen hundred and seventeen patients (2446 eyes) formed the basis for the study. Patients were included if there was more than 50% readability of the fundus photographs. OUTCOME MEASURES: Outcome measures were prevalence of any retinopathy and presence of referable (severe) retinopathy. Interobserver agreement was measured using the kappa statistic, and sensitivity and specificity of the screener were evaluated. RESULTS: The prevalence of retinopathy at the clinic was approximately 30%, but only about 12% was severe enough to warrant referral to the ophthalmology outpatient department. The endocrinologist was very accurate in determining cases requiring referral; there was 97% agreement with the reference standard, viz. the combined highest score of two experienced ophthalmologists (gold standard). Correlation on the determination of any retinopathy was less accurate (80% agreement), mostly owing to the endocrinologist reporting more isolated microaneurysms than the ophthalmologists. The screening method used gave a sensitivity of 83% and specificity of 99% which are within recommended standards. CONCLUSIONS: The screening strategy using a mydriatic fundus camera at the diabetic clinic was found to be effective and accurate and greatly reduced the number of possible referrals to the ophthalmology outpatient department.

Adult↗

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.

Adolescent↗

Image structure clustering for image quality verification of color retina images in diabetic retinopathy screening.

Reliable verification of image quality of retinal screening images is a prerequisite for the development of automatic screening systems for diabetic retinopathy. A system is presented that can automatically determine whether the quality of a retinal screening image is sufficient for automatic analysis. The system is based on the assumption that an image of sufficient quality should contain particular image structures according to a certain pre-defined distribution. We cluster filterbank response vectors to obtain a compact representation of the image structures found within an image. Using this compact representation together with raw histograms of the R, G, and B color planes, a statistical classifier is trained to distinguish normal from low quality images. The presented system does not require any previous segmentation of the image in contrast with previous work. The system was evaluated on a large, representative set of 1000 images obtained in a screening program. The proposed method, using different feature sets and classifiers, was compared with the ratings of a second human observer. The best system, based on a Support Vector Machine, has performance close to optimal with an area under the ROC curve of 0.9968.

Color↗

School eye health appraisal.

School children form an important large target group which must be screened adequately for early detection of eye diseases and prevention of blindness. A total approach in a school eye health programme must include teacher orientation and health education of children in addition to screening for eye diseases. The ocular morbidity pattern in 5135 school children of Jodhpur is discussed in this paper and it is hoped that it will be an indicator to all eye care agencies to help plan their priorities in the delivery of school based eye care.

Adolescent↗

Assessing progression and efficacy of treatment for diabetic retinopathy following the proliferative pathway to blindness: implication for diabetic retinopathy screening in Taiwan.

AIMS: The natural history and treatment efficacy of diabetic retinopathy (DR) play important roles in the evaluation of screening. Therefore, the natural history of DR and rates of transition after treatment (including metabolic control and laser photocoagulation) from no diabetic retinopathy (NDR) to blindness were quantified. METHODS: We studied a cohort of 795 patients with diabetes mellitus (DM) receiving fundus examination in the ophthalmology out-patient department of one medical centre between 1 January 1990 and 31 December 1992 in Taiwan. Follow-up data until 31 December 1998 were collected by chart review. Two multistate Markov models were proposed to assess the efficacy of the treatment regime in reducing progression to blindness. RESULTS: The average times spent in states (i) no diabetic retinopathy (NDR), (ii) background diabetic retinopathy (BDR), (iii) preproliferative diabetic retinopathy (PPDR), and (iv) proliferative retinopathy (PDR) were 10.86 years, 8.33 years, 1.67 years, and 2.17 years, respectively. Early detection of PPDR may lead to a 60% reduction in PDR and an 83% reduction in blindness. Simulated results based on these parameters show that an annual screening programme, a biennial screening regime and a 4-yearly screening regime can lead to 54% (95% confidence interval (CI): 44-62%), 51% (95% CI: 41-59%), and 46% (95% CI: 36-54%) reductions in blindness, respectively. CONCLUSIONS: Assessing the progression of DR following the proliferative pathway in this study suggests that screening for DR is worthwhile and that a 4-year interscreening interval for patients as yet without DR may be justified.

Adult↗

Retinopathy of prematurity: screening and optimal use of the ophthalmologist's time.

In recent years it has been standard practice to recommend that indirect ophthalmoscopy be carried out between six and nine weeks of age in very low birthweight infants to screen for the presence of retinopathy of prematurity (ROP). Following this recommendation we examined 85 infants over a two-year period. Acute ROP occurred in 29 (34%), and two (2.4%) developed cicatricial disease. One-third of infants were initially examined slightly earlier or later than the strict six to nine week limits, but all except three infants were examined between 35 and 42 weeks gestation. One infant born at 26 weeks gestation, was examined 'too late' in that she had stage 4 disease when first seen at 11 weeks of age. Recent information on the natural history of ROP, and confirmation of the efficacy of treatment with cyotherapy, suggested that the timing of an initial screening examination for ROP needed reassessment. From our experience and a review of the literature we recommended that infants of less than 1000 g birthweight or less than 28 weeks gestation have an initial examination at six weeks of age; for infants of 1000 to 1250 g birthweight or 28 to 30 weeks gestation examination continue to be at six to nine weeks of age; and for infants of more than 1250 g birthweight or 31 weeks gestation screening at six to nine weeks of age is only necessary if the infant has had an unstable course or prolonged oxygen requirements. Such a protocol would not place too great a burden on ophthalmological services and would direct efforts towards the group of infants most at risk of severe visual handicap.

Follow-Up Studies↗

The cost-effectiveness of various modes of screening for primary open angle glaucoma.

Various modes of screening for glaucoma were defined in terms of different combinations of the three main tests (ophthalmoscopy (O), tonometry (T), and perimetry (P)), together with associated referral criteria. The number of referrals and true positives generated by each mode was estimated for a model population, which was distributed with respect to age, intraocular pressure (IOP), optic disc condition, visual field defects, family history of glaucoma, and myopic status, as indicated by epidemiological studies. The costs of primary examination, and also of the secondary examination of referrals, were estimated for each mode, thus enabling the total cost per true positive to be calculated (in Pound sterling at 1995 UK prices, subsequently converted to US dollars at Pound 1.00 = $1.55.) The modes using O and T routinely, with P either routinely or selectively on all glaucoma high-risk groups, were found to provide the best balance between sensitivity (> or = 80%) and cost per true positive. The latter was around $850 when the cost of ophthalmoscopy could be shared as part of a general eye examination. The calculations assumed a 0.6% prevalence of previously undetected glaucomas in the community: with higher prevalences, costs per true positive would be lower. Screening the 40-59 years age group was found to be about as economic as for older people, when life expectancy was taken into account. It was concluded that glaucoma screening of people over age 40 years could be justifiable, provided that it is worth more than about $850 to detect a new case. Whilst based on UK values, the analysis could be applied to different primary health care settings in other countries.

Adolescent↗

Anterior elevation maps as the screening test for the ablation power of previous myopic refractive surgery.

PURPOSE: We classified the Orbscan anterior elevation maps in normal eyes (under myopic, emmetropic and hyperopic conditions) and in those after myopic refractive surgery. We did this classification to demonstrate how Orbscan anterior elevation maps are useful in screening for the existence and extent of previous myopic refractive surgery. Such a classification can help clinicians interpret preoperative and postoperative topographies. METHODS: We measured for visual acuity and refractive power in 4800 eyes. After a slit-lamp examination, a corneal topography exam was performed with an Orbscan corneal topography system. The eyes were divided into two groups, with Group I representing those who had not had refractive surgery (4438 eyes). Group II included those who had undergone previous refractive surgery to correct myopia (362 eyes). RESULTS: In Group I, the central island type (43.0%) was the most common, followed by the temporal ridge (25.8%), the with-the-rule regular ridge (16.7%), the against-the-rule regular ridge (6.6%), the nasal ridge (4.0%), and the saddle type (2.1%). In Group II, the depressed lake type (69.9%) was most common, followed by the de-centered ablation type (21.3%). The trend line of the postoperative central anterior surface elevation (E) and the ablation power of refractive surgery were calculated. Ablation power of refractive surgery = 0.0047 E + 0.0083 CONCLUSIONS: This study demonstrates that it is possible to use Orbscan anterior elevation maps to screen for the extent of previous refractory surgery used in the correction of myopia. This study may also be useful in understanding the shapes of Orbscan anterior elevation maps before and after myopic refractive surgery as well as in determining the degree of ablated myopic refractive power and decentration.

Adult↗

The Alaska Blind Child Discovery project: rationale, methods and results of 4000 screenings.

BACKGROUND: Photoscreening allows lay persons to adapt the Enhanced Brückner Test to preschoolers in an attempt to identify refractive amblyopia. The Alaska Blind Child Discovery (ABCD) project is charitably funded and administered. METHODS: MTI photoscreening was offered to children in rural and urban communities in southern Alaska from 1996 through June 1999. Parents answered questions concerning the child's health, family ocular history and whether the child had any eye "Warning Signs." The MTI images were interpreted by two eye doctors using a modification in MTI published guidelines. RESULTS: Out of 4000 screenings performed on 3930 children, there was an overall "not normal" interpretation of 9% and an inconclusive rate of 1%. The mean S.D. age was 3.9 2 years. Only 6% had had a prior eye exam. The average number of Polaroid pictures per screening was 1.16. Follow-up data on "not normal" results was obtained on just over 50%. The positive predictive value during the first two years was 77% but improved to 92% from 1998-1999. Affirmative answers to the questions concerning previous eye exam, child's health, siblings eye health and positive "Warning Signs" were significantly associated with "not normal" interpretations but affirmative answers about eye health of mother, father and relatives were not. Community penetrance of photoscreening to the target age-group ranged from only 5% for Anchorage to almost 100% for the Bristol Bay public health nurses. Five percent of parents of "positive" results surveyed would not have recommended screening for their friends. Equipment functioned dependably even in remote Alaska. CONCLUSION: Charitable volunteer Polaroid photoscreening detected amblyopia and significant pediatric eye disease in over 300 children during the first 3.5 years of ABCD.

Alaska↗

Non-contact tonometry: an ideal method for mass screening.

We evaluated one of the new non-contact tonometers, the Pulsair non-contact tonometer, to assess its accuracy and reliability. Measurements on 101 eyes were used to assess its accuracy against Goldmann tonometry measurements, and another 24 eyes were used to assess its reliability (reproducibility). The results showed the instrument to be highly accurate and reliable in measurement.

Evaluation Studies as Topic↗

Influence of test reliability on the screening performance of frequency-doubling perimetry.

PURPOSE: To investigate the influence of test reliability on the screening performance of frequency-doubling perimetry (FDT). DESIGN: Cross-sectional study. METHODS: FDT sensitivity and specificity were calculated three times using three different strategies for handling unreliable (that is, >0 reliability indices outside normal limits) and unfeasible (that is, could not be completed) tests in 452 glaucoma patients from our outpatient department and 237 healthy subjects recruited outside the hospital. RESULTS: Unreliable (P = .01) and unfeasible (P < .001) tests occurred more frequently in glaucoma patients when compared with healthy subjects. Best screening performance was obtained by interpreting unreliable tests as if they were reliable and considering unfeasible tests as positive. With this strategy, sensitivity was 0.90 (95% confidence interval 0.87-0.93) and specificity 0.81 (95% confidence interval 0.76-0.86). CONCLUSIONS: Unreliable and unfeasible FDT tests appear to contain useful information.

Cross-Sectional Studies↗

Prevalence of pigment dispersion syndrome in a population undergoing glaucoma screening.

The prevalence of pigment dispersion syndrome is thought to be relatively uncommon. Extrapolation of prevalences from glaucoma practices would suggest about 25,000 to 220,000 persons in the United States, an order of magnitude spread. By performing two population screenings that included slit-lamp examination, we detected pigment dispersion syndrome in 18 of 934 individuals. Sixteen of these were white, so that the prevalence of pigment dispersion syndrome in this group was 2.45%. We suggest that many more persons than previously believed may be at risk to develop pigment dispersion.

Adult↗

Results of treatment of amblyopia with a screening program for early detection.

The Swedish program for early intervention in children with visual dysfunction, was evaluated with respect to the results of treatment of amblyopia. One hundred and seventy-two amblyopic children were examined before and at 6, 12 and 18 months after the beginning of treatment. The mean visual acuity of the amblyopic eye was 0.76 and the mean ratio of visual acuity between the two eyes was 0.75 or better in all types of amblyopia. Children with strabismic amblyopia showed slightly poorer treatment results than the other types, in spite of the fact that their amblyopia had been detected earlier than the others. The results attest to the importance of careful screening of monocular visual acuity in all children, which in Sweden occurs at 4 years of age. This provides a good basis for detection and treatment of amblyopia. Only one child in the group had a visual acuity at 0.2 and may therefore be at risk for visual handicap if the better eye should be lost later in life.

Amblyopia↗

Prevalence of amblyopia in old people without previous screening and treatment. An evaluation of the present prophylactic procedures among children in Denmark.

An epidemiological study of amblyopia was performed among old people without previous screening and treatment. The study revealed a prevalence of 2.9% (strabismic in 2.3%, anisometropic in 0.6%). Present residual amblyopia among Danish school children is about 1% according to literature. The rate of cure of amblyopia by the present Danish system of prophylaxis and treatment is estimated to be 60-70%.

Aged↗

The reliability of interpretation of photoscreening results with the off PS-100 in Headstart preschool children.

BACKGROUND: Photoscreening has emerged as one of the newest means of screening children to detect amblyogenic factors. In the preschool population, it is important to reliably screen children who are at risk for developing amblyopia. This research was undertaken to determine the reliability of the interpretation of photoscreening results in a Headstart preschool population. METHODS: Fifty-four African-American children aged 3 to 5 years of age were examined using the MTI PS-100 photorefractor. Five health care professionals with no prior knowledge of photoscreening techniques were asked to perform independent, masked interpretations of a set of 54 Polaroid snapshots. Their interpretations followed a training session by a company consultant. RESULTS: The kappa coefficient for reliability of interpretation between observers was 0.55. This kappa value indicates that there was moderate agreement between the observers when identifying amblyogenic conditions in a child. CONCLUSIONS: Non-vision professionals using this device for the assessment of children will probably achieve only moderate levels of agreement on pass-fail decisions at first. Higher reliability reported previously by more experienced photoscreeners indicates that agreement could improve with advanced training, feedback regarding diagnostic findings, and experience. Methods to improve the technique, the device, or the training of the examiners are discussed.

Amblyopia↗

Teacher's questionnaire for vision problems: is it a help or a hindrance for school health screening?

The importance of early detection of vision problems in children is widely accepted. Screening by nurses in the first year of school is important in such early detection. The feasibility of using a questionnaire for teachers in place of the traditional screen was examined. In addition, the effect of prior in-service training for teachers on the results of the questionnaire survey was assessed. The questionnaire had poor sensitivity and specificity. Used as the sole screen, it would have resulted in the unnecessary referral of healthy children, and more importantly, children with visual defects would have been missed. Further, there was no improvement in the outcome when prior in-service training on the questionnaire had been given. The questionnaire for teachers, as given, was an unsatisfactory alternative to the screening by health professionals and was not supported by this study.

Child↗