Accuracy of the smartphone-based nonmydriatic retinal camera in the detection of sight-threatening diabetic retinopathy

Purpose: To evaluate the sensitivity and specificity of smartphone-based nonmydriatic (NM) retinal camera in the detection of diabetic retinopathy (DR) and sight-threatening DR (STDR) in a tertiary eye care facility. Methods: Patients with diabetes underwent retinal photography with a smartphone-based NM fundus camera before mydriasis and standard 7-field fundus photography with a desktop mydriatic fundus camera after mydriasis. DR was graded using the international clinical classification of diabetic retinopathy system by two retinal expert ophthalmologists masked to each other and to the patient's identity. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to detect DR and STDR by NM retinal imaging were assessed. Results: 245 people had gradable images in one or both eyes. DR and STDR were detected in 45.3% and 24.5%, respectively using NM camera, and in 57.6% and 28.6%, respectively using mydriatic camera. The sensitivity and specificity to detect any DR by NM camera was 75.2% (95% confidence interval (CI) 68.1–82.3) and 95.2% (95%CI 91.1–99.3). For STDR the values were 82.9% (95% CI 74.0–91.7) and 98.9% (95% CI 97.3–100), respectively. The PPV to detect any DR was 95.5% (95% CI 89.8–98.5) and NPV was 73.9% (95% CI 66.4–81.3); PPV for STDR detection was 96.7% (95% CI 92.1–100)) and NPV was 93.5% (95% CI 90.0–97.1). Conclusion: Smartphone-based NM retinal camera had fairly high sensitivity and specificity for detection of DR and STDR in this clinic-based study. Further studies are warranted in other settings.

Biochemical and dynamic studies of collagen from human normal skin and keloid tissue.

Keloids are exuberant scars, in which collagen, fibronectin and glycosaminoglycans are overdeposited. Biochemical analysis of the collagen isolated from normal skin and keloid tissue by pepsin treatment, indicated an increase in the type III and GAG content. Viscosity measurements of collagen from normal skin and keloid tissue were used in the present study to establish the interaction between collagen and GAG. Physico-chemical properties such as intrinsic viscosity, reduced viscosity and hydrated volume were computed from viscosity measurements. These measurements were also used to determine the denaturation temperature of collagen which was further confirmed by DSC measurements. Chondroitinase has been used in this study to probe the influence of GAG on the physico-chemical characteristic of keloid collagen.