Retinal Vessel Tortuosity Research Articles

Retinal Arteriolar Tortuosity is Associated With Retinopathy and Early Kidney Dysfunction in Type 1 Diabetes

To examine the association of retinal vessel tortuosity with diabetic retinopathy and early nephropathy in type 1 diabetes. Cross-sectional. A total of 1159 participants with type 1 diabetes aged 12 to 20 years, attending diabetes clinics in Children's Hospital at Westmead, Sydney, Australia between 1990 and 2002, were included. Retinal photography and clinical examinations were performed during the baseline visit to assess diabetic retinopathy and albumin excretion rate (AER). Retinal vessel tortuosity was measured from digitized retinal photographs using a semi-automated computer program by a single grader masked to participants' characteristics. Diabetic retinopathy was defined as ETDRS level ≥21 (mild nonproliferative retinopathy) and early kidney dysfunction was defined as AER ≥7.5 μg/min. Of 944 patients (81.4%), 85 (9.0%) had signs of retinopathy only, 250 (26.5%) had early kidney dysfunction only, and 85 (9.0%) had both retinopathy and early kidney dysfunction. In multivariate analysis, higher arteriolar tortuosity was associated with retinopathy (odds ratio [OR] 2.01, 95% confidence interval [CI] 1.23-3.29, the highest quartile vs the remaining 3 quartiles), early kidney dysfunction (OR 1.56, 95% CI 1.06-2.28, per standard deviation [SD] increase), or coexistence of both complications (OR 1.96, 95% CI 1.21-3.24, the highest quartile vs the remaining 3 quartiles). Greater retinal arteriolar tortuosity was independently associated with retinopathy and early stage of nephropathy in type 1 diabetes. These findings may offer the potential of quantitative measurement of retinal vessel tortuosity for diabetic complication risk assessment.

Computer-assisted image analysis of temporal retinal vessel width and tortuosity in retinopathy of prematurity for the assessment of disease severity and treatment outcome

To quantify the severity of retinopathy of prematurity (ROP) through temporal retinal vessel diameter and tortuosity by the use semiautomated analysis and to evaluate the effects of laser treatment on retinal vessel measurements. A total of 176 RetCam digital fundus images from 63 infants diagnosed with ROP between January 2005 and December 2008 were retrospectively analyzed with Retinal Vessel Measurement V5.8 software. Patients were classified into 1 of 3 groups: stage 1 and 2 (Group 1), stage 3 not requiring treatment (Group 2), and stage 3 requiring treatment (Group 3). Diameter and tortuosity of the 4 major temporal retinal arteries and veins close to the optic disk were quantified. Tortuosity was measured as central (within 2 disk diameters from the center of the optic disk) and paracentral (from 2 to 4 disk diameters). For Group 3, measurements of vessels immediately before treatment and all follow-up post-treatment measurements of vessels were analyzed. Differences in central and paracentral arteriolar tortuosity were pronounced. The average central arteriolar tortuosities were 1.12 ± 0.018 for Group 1, 1.13 ± 0.018 for Group 2, and 1.32 ± for Group 3; the paracentral arteriolar tortuosities were 1.11 ± 0.019 for Group 1, 1.12 ± 0.019 for Group 2, and 1.31 ± 0.02 for Group 3. In the post-treatment analysis of Group 3 patients, significant reductions in all vascular measurements were observed compared to pre-treatment, except for central and paracentral vein tortuosity. Computerized systems can be used to objectively assess differences in vascular parameters between ROP stages.

Retinal vascular tortuosity in persons with diabetes and diabetic retinopathy

The aim of this hypothesis was to examine the association of retinal vessel tortuosity with diabetes and diabetic retinopathy (DR). A clinic-based study of 327 participants (224 with diabetes and 103 non-diabetic controls) aged ≥ 18 years. DR was graded from fundus photographs according to the modified Airlie House Classification system and categorised into mild non-proliferative DR (NPDR), moderate NPDR and vision-threatening DR (VTDR). Retinal vessel tortuosity was measured from disc-centred retinal photographs. Measurements were taken, using a semi-automated computer program by a single grader, of arterioles and venules within 0.5 to 2 disc diameters away from the optic disc. There were 114 (44%) participants with DR. In the multivariate analysis, retinal arteriolar and venular tortuosity were increased in participants with diabetes without DR (mean difference 12.4 × 10(-5) and 13.3 × 10(-5), respectively; both p < 0.05) and in those with DR (mean difference 15.4 × 10(-5) and 15.0 × 10(-5), respectively; both p < 0.01) compared with non-diabetic participants. Among participants with diabetes, increased arteriolar tortuosity was significantly associated with mild NPDR (OR 1.53, 95% CI 1.03-2.05, per SD increase in arteriolar tortuosity) and moderate NPDR (OR 1.67, 95% CI 1.10-2.55) but not VTDR (OR 0.91, 95% CI 0.54-1.54). No association with DR was found for venular tortuosity. Persons with diabetes had more tortuous retinal vasculature than persons without diabetes. In persons with diabetes, increased arteriolar tortuosity was associated with mild and moderate stages of DR. This suggests that retinal vascular tortuosity might be an early indicator of microvascular damage in diabetes; thus, further investigation is indicated.

Bietti crystalline retinal dystrophy with subfoveal neurosensory detachment and congenital tortuosity of retinal vessels: case report

A 34-year-old man presented with reduction and distortion of vision in both the eyes. The best-corrected vision was 20/20 parts, N6 in either eye. The external and slit lamp examination of both the eyes was unremarkable. The fundus examination showed multiple intraretinal crystalline deposits at the posterior pole, extending up to midperiphery, tortuous retinal blood vessels with S-shaped deflections, and absent foveal reflex in both the eyes. There were no corneal crystals, and the color vision was defective in both the eyes. Fundus autofluorescence and fundus fluorescein angiogram (FFA) were suggestive of geographic areas of retinal pigment epithelium (RPE) and choriocapillary (CC) loss. OCT revealed subfoveal neurosensory detachment. Flash ERG and EOG were normal except for a slight decrease in amplitude and delay in latency of pattern ERG waveforms. The Humphrey's visual field showed paracentral scotoma with reduction in the amplitude of waveforms from the corresponding area in the multifocal ERG in both the eyes. Systemic evaluation for crystalline retinopathy was unremarkable. He was diagnosed to be a case of Bietti crystalline retinopathy (local/regional variant). The subfoveal neurosensory detachment could represent early RPE dysfunction caused by these crystals and could account for the mild visual disturbance in both the eyes. Retinal vascular tortuosity and neurosensory detachment seen in this case is the first time to be reported in literature.

Ocular changes in multi-transfused children with β-thalassaemia receiving desferrioxamine: A case-control study

Objectives. This study was planned to determine the prevalence of ocular abnormalities in multi-transfused children with β-thalassaemia receiving desferrioxamine and to determine the association of abnormalities with the patients’ age, serum ferritin level, haemoglobin concentration, and dosage and duration of treatment with desferrioxamine. Methods. Twenty-five thalassaemic children receiving desferrioxamine and attending the day-care centre of a tertiary care hospital in Delhi, India, and 25 healthy age-matched controls were examined to determine the prevalence and pattern of ocular abnormalities. A refraction test, the visual evoked response and fluorescein angiography were done where applicable. Ocular changes were correlated with serum ferritin levels, the dosage and duration of chelation with desferrioxamine, and pre-transfusion haemoglobin levels. Results. None of the children reported any visual symptoms. The prevalence of ocular abnormalities in the thalassaemic group was 36% (9/25). Ocular changes seen included cataract (5/25), blurred optic disc margins (6/25) and dilatation and tortuosity of retinal vessels (2/25). The thalassaemic children had a significantly higher prevalence of cataract than the controls ( p <0.05). Prevalence of cataract was associated with serum ferritin values above 4500 ng/ml ( p <0.05), and blurring of disc margins was significantly associated with increased duration ((5 years) and frequency ((5 times/week) of desferrioxamine administration. A positive correlation was seen between the incidence of cataract and blurred disc margins. Conclusions. Children with thalassaemia should be screened periodically for ocular abnormalities. Rational usage of desferrioxamine and use of newer chelating agents will reduce the prevalence of these abnormalities.

Curcumin Prevents Experimental Diabetic Retinopathy in Rats Through Its Hypoglycemic, Antioxidant, and Anti-Inflammatory Mechanisms

The purpose of this study was to evaluate the therapeutic potential of oral curcumin (1 g/kg body weight of rat) in the prevention and treatment of streptozotocin-induced diabetic retinopathy in Wistar albino rats. The treatment was carried out for a period of 16 weeks in diabetic rats and evaluated for hyperglycemic, antioxidant (superoxide dismutase, catalase, and glutathione), and inflammatory parameters (tumor necrosis factor-α, vascular endothelial growth factor). Rat fundus was observed weekly to see any visible changes in the retina, such as tortuosity and dilation of retinal vessels. Histological changes were evaluated by transmission electron microscopy. Treatment with curcumin showed significant hypoglycemic activity compared with the diabetic group. Retinal glutathione levels were decreased by 1.5-fold, and antioxidant enzymes, superoxide dismutase and catalase, showed >2-fold decrease in activity in the diabetic group; on the other hand, curcumin positively modulated the antioxidant system. Proinflammatory cytokines, tumor necrosis factor-α and vascular endothelial growth factor, were elevated >2-fold in the diabetic retinae, but prevented by curcumin. Transmission electron microscopy showed degeneration of endothelial cell organelles and increase in capillary basement membrane thickness in diabetic retina, but curcumin prevented the structural degeneration and increase in capillary basement membrane thickness in the diabetic rat retinae. Based on the above results, it may be concluded that curcumin may have potential benefits in the prevention of retinopathy in diabetic patients.

Resolution of total retinal detachment in Coats’ disease with intravitreal injection of bevacizumab

Dear Editor Coats’ disease is a nonhereditary condition of primary retinal telangiectasia that is characterized by dilation and tortuosity of retinal blood vessels, multiple aneurysms, and exudates. Coats’ disease is usually unilateral, affects young boys, and causes severe visual loss due to exudative retinal detachment. Routine photocoagulation, cryotherapy, and even surgery may have poor therapeutic effects for total retinal detachment. We report a case of Coats’ disease with total retinal detachment that demonstrated a remarkable response to intravitreal bevacizumab injection. A 3-year-old Chinese boy presented with a 2-year history of left eye squinting. The corneal light reflection test showed a 15° exotropia of the left eye, which could not be corrected. The grating visual acuity of the right eye was 0.2, and the left eye did not respond to stimuli. Examination under anesthesia showed total retinal detachment of the left eye, with extensive subretinal exudates accompanied by dilated tortuous vessels (Fig. 1a), and the intraocular pressures were 14 mmHg bilaterally. Type-B ultrasonography indicated total retinal detachment of the left eye (Fig. 2a). A diagnosis of Coats’ disease stage 3B was made via Shields’ classification [1]. After receiving consent from the boy’s parents for a trial of off-label use of bevacizumab, we performed intravitreal bevacizumab injection (1.25 mg/0.05 ml) three times at 6week intervals. Eight weeks after the last injection, the dilated vessels were alleviated, and the subretinal exudates and fluid were decreased (Fig. 1b). Type-B ultrasonography revealed a significant anatomical improvement of the retina compared with pre-injection, with only a small range of superior retinal detachment. Within 15 weeks after the last injection, the corrected visual acuity of the left eye was 20/ 125 and Type-B ultrasonography showed further resolution of the retinal detachment (Fig. 2b). Diagnosing Coats’ disease is a lengthy process, and there is still confusion about the definition. The most widely accepted diagnostic criteria of Coats’ disease include idiopathic retinal telangiectasia, intraretinal and subretinal exudation, and frequent exudative retinal detachment without vitreous or retinal traction. Coats’ disease has no clear etiopathogenisis, but it is widely accepted that it is related to a defect in the development of the retinal vessels. Vascular endothelial growth factor (VEGF) plays an important role in the development of retinal vessels. Although basic investigations of Coats’ disease are rare, it is believed that VEGF induced by hypoxia may be part of the pathogenesis, considering the evidence of elevated intravitreal VEGF levels of a patient with stage 4 Coats’ disease [2, 3]. The hypothesis suggests anti-VEGF therapies, which have been used in tumors and some neovascular diseases in ophthalmology, as possible therapies for Coats’ disease. Bevacizumab, a full-length humanized recombinant antibody against VEGF, is one of the anti-VEGF agents under consideration. There have been several encouraging reports about treating Coats’ disease with bevacizumab combined with triamcinolone injection or laser treatment [4–6]. To our knowledge, this is the first report of treating total retinal detachment caused by Coats’ disease using Financial support None.

Enzyme assay and clinical assessment in subjects with a Chinese hotspot late‐onset Fabry mutation (IVS4 + 919G→A)

Newborn screening for Fabry disease in Taiwan Chinese has revealed a high incidence of the late-onset GLA mutation IVS4 + 919G→A (∼1 in 1,500-1,600 males). We studied 94 adults with this mutation [22 men, 72 women; mean age: men 57.8 ± 6.0 (range 42-68), women 39.1 ± 14.1 years (range 19-82)]. Plasma α-galactosidase A activity assay was 10.4 ± 11.2% of normal in the men and 48.6 ± 19.5% of normal in the women. Echocardiography in 90 of the adults revealed left ventricular hypertrophy (LVH) in 19 (21%), including 14 of 21 men (67%) and 5 of 69 women (7%). Microalbuminuria, based on the urine albumin-to-creatinine ratio measured on at least two occasions, was present in 17 of 86 subjects (20%) (men: 5/20, 25%; women 12/66, 18%). At least one ocular manifestation consistent with Fabry disease was present in 41 of 52 subjects (79%) who underwent ophthalmologic examination, including 8 (15%) with conjunctival vessel tortuosity, 15 (29%) with cornea verticillata, 10 (19%) with Fabry cataract, and 34 (65%) with retinal vessel tortuosity. Among subjects over 40 years of age, men were more likely than women to have LVH [14/21 (67%) vs 5/25 (20%), p < 0.001]. Cardiovascular, renal and ocular abnormalities are highly prevalent in adult Taiwan Chinese subjects with the Fabry mutation IVS4 + 919G→A. Our findings contribute to the limited understanding of the course of this late-onset disease variant and underscore the need for close follow up in such patients.

Ophthalmological findings in children and adolescents with Silver–Russell syndrome

AimTo evaluate ophthalmological findings in children with Silver–Russell syndrome (SRS).MethodsAn ophthalmological evaluation including visual acuity (VA), refraction, strabismus, near point of convergence (NPC), slit-lamp examination, ophthalmoscopy, axial length measurements and...

Ocular manifestations of Fabry disease within in a single kindred

Background Fabry disease is an X-linked lysosomal storage disorder that causes progressive complications within the kidneys, brain, and heart. Ocular manifestations of this disease are often present at a very young age, thereby facilitating early diagnosis, before the signs and symptoms of renal disease, stroke, or hypertrophic cardiomyopathy. Early diagnosis by the eye care provider may eventually reduce the morbidity and mortality of this disease through the institution of therapy before the development of sclerotic end organ damage. This study evaluated 23 Fabry-affected members of a single cohort for the presence of ocular signs of Fabry disease. Methods Twenty-three patients of a single family were seen on a single day. Patients were given comprehensive ophthalmic examinations and completed a health and lifestyle questionnaire. Results Eight hemizygous men (mean age, 32.3 years) and 15 heterozygous women (mean age, 26.9 years) from a single family of 43 known Fabry patients were evaluated. Corneal verticillata was present in all patients. Additional findings in the male patients included anterior capsule opacity (25% total) and Fabry cataract (12.5%). Thinning of the retinal nerve fiber layer was observed in one man whose medical history was significant for stroke. Conjunctival and/or retinal vessel tortuosity was present in the majority of patients (62.5% and 75% of hemizygotes, respectively; 40% and 13.3% heterozygotes, respectively). Additional findings in the women included anterior capsule opacity. The majority of patients (87.5% hemizygotes, 60% heterozygotes) felt Fabry disease had an impact on their quality of life. Conclusions All evaluated patients who had Fabry disease had corneal verticillata, which generally does not affect vision and is readily recognizable by slit lamp examination. Greater than 60% showed conjunctival and/or retinal vessel tortuosity. The eye care provider can play a crucial role in the early recognition of ocular manifestations of Fabry disease and decrease both the time to accurate diagnosis and the delay in the institution of disease-modifying therapy.

Retinal arterial but not venous tortuosity correlates with facioscapulohumeral muscular dystrophy severity

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal-dominant disease beginning with facial and shoulder girdle weakness with variable progression. Exudative retinal detachment, retinal vessel irregularities on fluorescein angiography, and retinal vessel tortuosity have been found in association with FSHD. In this retrospective study, muscle affectedness severity was rated as mild, moderate, or severe by a neurologist masked to the retinal images. Three ophthalmologists masked to disease severity graded the degree of arterial and venous tortuosity on a scale of 1 to 4. An automated method estimated an index of tortuosity for arteries and veins from color fundus photographs. Spearman rank correlation coefficients were used to describe the relationship between retinal vessel tortuosity and disease severity. Seven patients with an average age of 13 years (range, 7-36 years) were selected. Correlation between the subjective tortuosity for arteries, and the severity of FSHD was 0.78 (p = 0.039). The correlation coefficient for venous tortuosity was -0.06 and was not significant (p = 0.882). The correlation coefficient between the average algorithmic computer-generated tortuosity indices for arteries and FSHD severity was high (0.85, p = 0.016), but for veins it was low and not significant (0.19, p = 0.662). The authors of previous reports have shown retinal vascular abnormalities did not correlate to FSHD disease severity. Our results suggest a correlation between the tortuosity of arteries and the severity of disease in FSHD patients. These results suggest the tortuosity of arteries can serve as a biomarker of severity of disease in these FSHD patients, either as determined by human experts or by an automated method.

Risk Stratification of Preplus Retinopathy of Prematurity by Semiautomated Analysis of Digital Images

To determine whether quantitative analysis of retinal vessel width and tortuosity from digital images discriminates which eyes with preplus retinopathy of prematurity (ROP) progress to treatment severity. Posterior pole images of eyes at first clinical diagnosis of preplus ROP were obtained using a 30 degrees-field, noncontact fundus camera. Width and tortuosity of retinal vessels were analyzed from digital images using computer-assisted image analysis software. Mean width and tortuosity of venules and arterioles were compared in 19 preplus eyes that regressed spontaneously and 11 preplus eyes that progressed to treatment severity. Receiver operating characteristic curve analysis was performed to assess whether width and tortuosity discriminated between groups. Mean widths of venules alone, arterioles alone, and the 3 widest vessels were higher in preplus progressed eyes (P < .04). Mean tortuosity of the 3 most tortuous vessels was higher in preplus progressed than in preplus regressed eyes (P = .01). Most vessel width and tortuosity variables predicted which eyes with preplus progressed to treatment moderately well, with an area under the receiver operating characteristic curve of 0.72 to 0.82. Digital image analysis of retinal vessel width and tortuosity may be useful in predicting which preplus ROP eyes will require treatment. Because vascular abnormalities are a continuum and clinical diagnosis is subjective, quantitative analysis may improve risk stratification for ROP.

Modeling the Tortuosity of Retinal Vessels: Does Caliber Play a Role?

The tortuosity of retinal blood vessels is a diagnostic parameter assessed by ophthalmologists on the basis of examples and experience; no quantitative model is specified in clinical practice. All quantitative measures proposed to date for automatic image analysis purposes are functions of the curvature of the vessel skeleton. We suggest in this paper that curvature may not be the only quantity involved in modeling tortuosity, and that vessel thickness, or caliber, may also play a role. To support this statement, we devise a novel measure of tortuosity, depending on both curvature and thickness, and test it with 200 vessels selected by our clinical author from the public digital retinal images for vessel extraction database. Results are in good accordance with clinical judgment. Comparative experiments show performance similar to or better than that of four measures reported in the literature. We conclude that there is reasonable evidence supporting the investigation of tortuosity models incorporating more measurements than just skeleton curvature, and specifically vessel caliber.

A Case of Bilateral Papilledema and Visual Field Defect in Pediatric Idiopathic Intracranial Hypertension

Purpose: To report a case of bilateral papilledema and visual field defect in pediatric idiopathic intracranial hypertension. Case summary: The 5-year-old female patient was admitted to the hospital, complaining of headache and vomiting of 3 weeks duration. After admission, she complained of diplopia. The uncorrected visual acuity was 0.3 in the right eye and 0.8 in the left. An alternative prism cover test showed approximately 35 PD esotropia, with a -2 abduction limitation of both eyes. Fundus examination showed bilateral papilledema and peripapillary retinal hemorrhages. No abnormality was found in the MRI and CT, symptoms of headache, vomiting, bilateral papilledema, and esotropia with normal neurologic examination. Therefore, she was diagnosed with pediatric idiopathic intracranial hypertension. In Humphrey visual field test, MD was -14.15 dB in right and -16.58 dB in the left eye. Also, the general sensitivity of visual field decreased. Acetazolamide (Diamox) was given orally for 30 days. Forty-four days after the initial visit, peripapillary retinal hemorrhages and vessel tortuosity decreased. Furthermore, visual acuity improved to 1.0 in the right eye and 0.9 in the left. The esotropia reduced to 5 PD, and MD improved to -4.83 dB in the right eye and -5.24 dB in the left.

Measurement of retinal vascular tortuosity and its application to retinal pathologies

The tortuosity of retinal blood vessels is an important diagnostic indicator for a number of retinal pathologies. We applied robust quantitative tortuosity metrics, which are well suited to automated detection and measurement, to retinal fluorescein images of normal and diseased vessels exhibiting background diabetic retinopathy, retinitis pigmentosa and retinal vasculitis. We established the validity of the mean tortuosity (M) and the normalized root-mean-square tortuosity (K) by their strong correlation with the ranking of tortuosity by an expert panel of ophthalmologists. The low prevalences of the diseased conditions in the general population affect the classification process, and preclude the use of tortuosity for screening for all of these conditions simultaneously in the general population. Tortuosity may be useful as a screening test for retinitis alone, and may be useful for distinguishing diabetic retinopathy or vasculitis from normal in a discretionary (i.e. referred) population.

The anatomy of the rat eye with oxygen-induced retinopathy

Prior studies have documented the intertwined developmental courses of retinal blood vessel tortuosity (in fundus photographs) and retinal dysfunction (in electroretinographs) in Sprague-Dawley rat models of retinopathy of prematurity (ROP). Two such models, the "50/10 model" and the "75 model," are named after the oxygen regimens used to induce retinopathy and are characterized by distinct neurovascular courses that span a range of disease severity. In this study of 50/10 and 75 model rats, retinal flatmounts were used to study the full vasculature at postnatal day (P) 15, P19 and P30. In addition, the layers of the neural retina were measured in toluidine blue-stained cross sections. Finally, gross anatomic features of the eye, including axial length, retinal surface area, and the ratio of anterior to posterior axial-lengths were evaluated. Both clock hours of neovascularization (NV) and percent avascular retina (AR) peaked at P19 and resolved by P30. Through P19, NV was found in every 50/10 model rat, but in only 60% of 75 model rats. AR was positively related to NV. All inner layers of the retina (outer plexiform layer through ganglion cell layer) were attenuated in 50/10 model rats but, in the 75 model, no layer differed significantly from that in controls. The eyes in both ROP models were smaller than those of age-matched controls. The ratio of anterior to posterior axial-lengths ranged from 0.45 in controls through 0.37 in the 75 model to 0.32 in the 50/10 model. Thus, eye growth is altered in these rat models of ROP.

The changes of tortuosity and bifurcation angle of retinal vessels at the posterior pole in the eyes with high myopia

Objective To observe the changes of tortuosity and bifurcation angle of retinal arteries and veins in each quadrant of the posterior pole in eyes with high myopia. Methods The tortuosity and bifurcation angle of retinal vessels in each quadrant of the posterior pole in 32 patients (52 eyes) with high myopia and 22 healthy people (30 eyes) were observed and compared. The outcomes were analyzed by multivariate analysis of variance. Results The tortuosity of macular vessels and the artery from optic disc in eyes with high myopia was (1.29±1.10)×10-4 and (5.39±1.93)×10-5 respectively, and in the normal eyes was (4.15±2.38)×10-4 and (9.75±4.99)×10-5 respectively; there was significant difference between the two groups (t=1.99, 2.00; P<0.05). The bifurcation angle of superior nasal and inferior nasal retinal arteries in eyes with high myopia was(66.17±14.04)° and (61.20±11.02)° respectively, and in the normal eyes was (77.66±14.12)° and (85.86±16.45)° respectively; there was significant difference between the two groups (F=0.77, 0.83; P<0.05). The bifurcation angle of superior temporal and inferior temporal retinal veins in eyes with high myopia was (92.39±20. 36)° and (83.56±23.50)° respectively, and in the normal eyes was (79.45±15.94)° and (70.59±17.27)°; there was significant difference between the two groups (F=2.34, 1.83; P<0.05). Conclusions The vessel tortuosity of retinal arteries and the vessels extending from the optic disc to macula is smaller in eyes with high myopia, while the venous tortuosity has no change. The bifurcation angle of retinal arteries in the superior nasal and inferior nasal field was smaller in eyes with high myopia, while the venous tortuosity has no change. The bifurcation angle of retinal veins in the superior temporal and inferior temporal field was larger in eyes with high myopia. Key words: Myopia; degenerative/pathophysiology; Retinal vessels/pathophysiology; Fluorescein angiography

Measuring Retinal Vessel Tortuosity in 10-Year-Old Children: Validation of the Computer-Assisted Image Analysis of the Retina (CAIAR) Program

To examine the agreement of a novel computer program measuring retinal vessel tortuosity with subjective assessment of tortuosity in school-aged children. Cross-sectional study of 387 retinal vessels (193 arterioles, 194 veins) from 28 eyes of 14 children (aged 10 years). Retinal digital images were analyzed using the Computer Assisted Image Analysis of the Retina (CAIAR) program, including 14 measures of tortuosity. Vessels were graded (from 0 = none; to 5 = tortuous) independently by two observers. Interobserver agreement was assessed by using kappa statistics. Agreement with all 14 objective measures was assessed with correlation/regression analyses. Intersession repeatability (comparing morning and afternoon sessions) of tortuosity indices was calculated. Interobserver agreement of vessel tortuosity within one grade was high (kappa = 0.97), with total agreement in 56% of grades and 42% differing by +/-1 grade. Tortuosity indices based on subdivided chord length methods showed strong log-linear associations with agreed subjective grades (typically r > 0.6; P < 0.001). An approach that averages the distance from the vessel to chord length along the length of the vessel showed best agreement (r = 0.8; P < 0.0001). Tortuosity measures based on curvature performed less well. Intersession repeatability of the vessel to chord technique was good, differing by values equivalent to <1 in subjective grade. Tortuosity indices based on changes in subdivided chord lengths showed optimal agreement with subjective assessment. The relation of these indices to ethnicity and cardiovascular risk factors in childhood should be examined further, as these indices may be a useful indicator of early vascular function.

064: Reliability of digital vessel analysis in eyes at risk for retinopathy of prematurity

Introduction: Plus disease is currently the major determinant for treatment of retinopathy of prematurity (ROP). This study examines the reliability of measurements of retinal vessel tortuosity, width, and variation of width using 2 semiautomated digital image vessel analysis systems.

COMPUTER-ASSISTED ASSESSMENT OF PLUS DISEASE IN RETINOPATHY OF PREMATURITY USING VIDEO INDIRECT OPHTHALMOSCOPY IMAGES

"ROPtool" is a computer program that measures retinal blood vessel tortuosity. Our aim was to determine the feasibility and accuracy of analyzing images with ROPtool, which were obtained using video indirect ophthalmoscopy. Forty-five posterior pole still images captured from indirect ophthalmoscopy video clips were selected; 20 were selected for high quality and 25 were randomly selected. One of the authors (S.A.) used ROPtool to measure tortuosity for each quadrant of each image. Two of the authors (D.K.W. and S.F.F.) independently judged tortuosity on a 10-point scale, and their averaged grades were used as the reference standard. Among randomly selected images, ROPtool was able to trace at least two major vessels in 43 of 100 quadrants (43%). Lighter fundus pigment color was associated with ROPtool's ability to analyze images (P = 0.004). When considering analyzable images only, ROPtool's sensitivity in detecting tortuosity sufficient for plus disease was 83% (5/6) and specificity was 90% (18/20). ROPtool's sensitivity for pre-plus tortuosity was 100% (9/9) and specificity was 71% (12/17). ROPtool is useful for analyzing video indirect ophthalmoscopy images only when applied to those with high quality. When analyzing these images, ROPtool has very good accuracy compared to consensus of experienced examiners.