Based on the Gullstrand I model eye, a simplified model eye for testing fundus imaging device is designed. The model eye can reach the following requirements:(1) The refractive characteristics of the ocular refractive tissue are simulated, and the equivalent focal length in air is 17 mm; (2) The differences between relative refractive index differences of the adjacent materials of the simplified model eye and relative refractive index differences of any adjacent two layers (cornea and aqueous humor, aqueous humor and lens, lens and vitreous body) of the Gullstrand I model eye are not more than 1%; (3) In the case of the incident aperture diameter of 3 mm, the differences of radii of the diffuse spots formed by the paraxial light and the axial light are not more than 15%; (4) The differences of angles of chief ray and tangent line of the fundus are not more than 1°; (5) In the case of the incident aperture diameter of 3 mm, the differences of MTF values of the near axis light are not more than 0.1. The simplified model eye can be expected to be used for testing fundus imaging device instead of the test method in ISO 10940:2009 Ophthalmic instruments-Fundus cameras.
Cornea ; Fundus Oculi ; Lens, Crystalline ; diagnostic imaging ; Refraction, Ocular

OBJECTIVETo evaluate the diagnostic value of ultrasonography for trinitrotoluene (TNT) cataract.

METHODSThe morphology and internal echoes of 90 lenses of 45 TNT cataract patients and 120 lenses of 60 healthy adults were observed and compared using ultrasonography and slit lamp, and the hemodynamic parameters of the post-ophthalmic artery were also measured. The findings of the slit-lamp microscope were regarded as diagnostic criteria, and the sensitivity, specificity, and accordance rate of ultrasonography in the diagnosis of TNT cataract were calculated.

RESULTSThe sensitivity, specificity, and accordance rate of ultrasonography in the diagnosis of TNT cataract were 93.33%, 100.00%, and 97.14%, respectively; the positive and negative predictive values were 100% and 95.23%, respectively; the positive and negative likelihood ratios were 93.33 and 0.67, especuvey. With the progression TNT cataract, utrasonography showed that the lenses demonstrated morphological changes (spindle-shaped, spherical, and discoid morphologies), and the arc echoes of the posterior capsule were thickened and enhanced. The TNT cataract patients showed significantly lower peak systolic velocity and end-diastolic velocity of the ophthalmic artery (OA) and central retinal artery (P<0.01) and a significantly higher resistance index (P<0.05) than the healthy adults.

CONCLUSIONThe sensitivity of ultrasonography in the diagnosis of TNT cataract is similar to that of slit lamp. Ultrasonography can demonstrate objectively the shape, range, and degree of lens opacity in an efficient manner, which is conducive to the diagnosis and staging of TNT cataract by slit lamp, and can also provide hemodynamic information of the OA, thus providing new ideas for clinical physicians in evaluating the disease and clinical efficacy as well as exploring therapies.

Adult ; Case-Control Studies ; Cataract ; chemically induced ; diagnostic imaging ; Humans ; Lens, Crystalline ; diagnostic imaging ; Predictive Value of Tests ; Sensitivity and Specificity ; Slit Lamp ; Trinitrotoluene ; toxicity ; Ultrasonography

This project was aimed to develop a simple, convenient and reliable computer image processing software for the measurement of lens dimensions, including the radius of curvature of anterior lens surface (RCALS), the radius of curvature of posterior lens surface (RCPLS) and the lens volume (LV). On the basis of lens images captured by B ultrasound, our computer software was designed to calculate the three parameters of lens in accordance to geometry principle. This software comprises Program I and Program II, and they both possess different calculation methods. Then they were used in a group of normal volunteers who were recruited via randomization and the outcomes were compared. The results showed that the two programs were developed successfully, and the outcomes of RCALS, RCPLS and LV calculated by the two programs were similar. The standard deviation of Program II is smaller than that of Program I. The computer software for calculating RCALS, RCPLS and LV was characterized by scientific design and easy-to-use. In respect of calculating repetition, Program II was better than Program I, and it possesses prosperous prospect in terms of clinical research and application.
Adult ; Aged ; Female ; Humans ; Image Processing, Computer-Assisted ; methods ; Lens, Crystalline ; anatomy & histology ; diagnostic imaging ; Male ; Mathematical Computing ; Middle Aged ; Optics and Photonics ; Refraction, Ocular ; Software ; Ultrasonography

PURPOSE: To compare the clinical and anterior segment anatomical features in primary angle closure sub-groups based on configurations of iris root insertion. METHODS: Primary angle closure patients were imaged using anterior segment optical coherence tomography. Anterior chamber depth, iris curvature, iris thickness (IT) at the scleral spur and 500, 750, and 1,500 µm from the scleral spur (IT(0), IT(500), IT(750), and IT(1500)), lens vault, iris area, angle opening distance (AOD(500)), angle recess area (ARA(750)), and trabecular iris space area (TISA(750)) were measured. Iris root insertion was categorized into a non-basal insertion group (NBG) and basal insertion group (BG). RESULTS: In total, 43 eyes of 39 participants belonged to the NBG and 89 eyes of 53 participants to the BG. The mean age of participants was greater in the NBG than the BG (62.7 ± 5.7 vs. 59.8 ± 7.3 years, p = 0.043), and the baseline intraocular pressure was higher in the BG than the NBG (16.4 ± 4.4 vs. 14.9 ± 3.3 mmHg, p = 0.037). The BG showed a greater IT(0) (0.265 ± 0.04 vs. 0.214 ± 0.03 mm, p < 0.001) and iris area (1.59 ± 0.24 vs. 1.52 ± 0.27 mm2, p = 0.045), lower ARA(750) (0.112 ± 0.08 vs. 0.154 ± 0.08 mm2, p = 0.017) and AOD(500) (0.165 ± 0.07 vs. 0.202 ± 0.08 mm, p = 0.014) compared to the NBG. CONCLUSIONS: The BG had a narrower anterior chamber angle, thicker peripheral iris, and higher pretreatment intraocular pressure.
Anterior Eye Segment/*diagnostic imaging ; Female ; Glaucoma, Angle-Closure/diagnosis/physiopathology/*surgery ; Gonioscopy ; Humans ; *Intraocular Pressure ; Iridectomy/*methods ; Iris/diagnostic imaging/*surgery ; Lens, Crystalline/diagnostic imaging ; Male ; Middle Aged ; Prospective Studies ; Tomography, Optical Coherence/*methods