Ultrasound biomicroscopy (UBM) has been applied in ophthalmology for twenty years. It plays an important role in diagnosis of eye diseases, especially in glaucoma. After years of research, It has been developed in its structure, sensors, imaging technology and applied research.
Diagnostic Techniques, Ophthalmological ; Microscopy, Acoustic

Glaucoma is the leading cause of irreversible blindness, but its early symptoms are not obvious and are easily overlooked, so early screening for glaucoma is particularly important. The cup to disc ratio is an important indicator for clinical glaucoma screening, and accurate segmentation of the optic cup and disc is the key to calculating the cup to disc ratio. In this paper, a full convolutional neural network with residual multi-scale convolution module was proposed for the optic cup and disc segmentation. First, the fundus image was contrast enhanced and polar transformation was introduced. Subsequently, W-Net was used as the backbone network, which replaced the standard convolution unit with the residual multi-scale full convolution module, the input port was added to the image pyramid to construct the multi-scale input, and the side output layer was used as the early classifier to generate the local prediction output. Finally, a new multi-tag loss function was proposed to guide network segmentation. The mean intersection over union of the optic cup and disc segmentation in the REFUGE dataset was 0.904 0 and 0.955 3 respectively, and the overlapping error was 0.178 0 and 0.066 5 respectively. The results show that this method not only realizes the joint segmentation of cup and disc, but also improves the segmentation accuracy effectively, which could be helpful for the promotion of large-scale early glaucoma screening.
Diagnostic Techniques, Ophthalmological ; Fundus Oculi ; Glaucoma/diagnostic imaging* ; Humans ; Neural Networks, Computer ; Optic Disk/diagnostic imaging*

Glaucoma is one of blind causing diseases. The cup-to-disc ratio is the main basis for glaucoma screening. Therefore, it is of great significance to precisely segment the optic cup and disc. In this article, an optic cup and disc segmentation model based on the linear attention and dual attention is proposed. Firstly, the region of interest is located and cropped according to the characteristics of the optic disc. Secondly, linear attention residual network-34 (ResNet-34) is introduced as a feature extraction network. Finally, channel and spatial dual attention weights are generated by the linear attention output features, which are used to calibrate feature map in the decoder to obtain the optic cup and disc segmentation image. Experimental results show that the intersection over union of the optic disc and cup in Retinal Image Dataset for Optic Nerve Head Segmentation (DRISHTI-GS) dataset are 0.962 3 and 0.856 4, respectively, and the intersection over union of the optic disc and cup in retinal image database for optic nerve evaluation (RIM-ONE-V3) are 0.956 3 and 0.784 4, respectively. The proposed model is better than the comparison algorithm and has certain medical value in the early screening of glaucoma. In addition, this article uses knowledge distillation technology to generate two smaller models, which is beneficial to apply the models to embedded device.
Humans ; Optic Disk/diagnostic imaging* ; Glaucoma/diagnosis* ; Algorithms ; Diagnostic Techniques, Ophthalmological ; Databases, Factual

PURPOSE: To compare and evaluate the total and internal aberrations measured by two aberrometers: the laser ray tracing aberrometer (iTrace, Tracey Technology) and the automatic retinoscope aberrometer (OPD Scan, Nidek). METHODS: A total of 54 healthy eyes were enrolled in the study. Following pupil dilation, aberrations were measured with the iTrace and OPD Scan. We compared the aberrations obtained from measurements obtained at pupillary diameters of 4 mm and 6 mm with the OPD Scan and iTrace. Aberrations of internal optics and total aberrations were compared for the two aberrometers. For each aberrometer and each eye, the averaged Zernike data were used to calculate various root-mean-square (RMS) data. These parameters, together with the refractive parameters, were then analyzed and complimented by paired t-tests. RESULTS: At a pupil diameter of 4 mm, the number of total aberrations in the entire eye showed significant differences for the mean values of spherical aberrations (Z4,0) obtained with the OPD Scan and iTrace aberrometers (p=0.001). Aberrations of the internal optics showed significant differences in the mean values of total RMS, coma (Z3,-1), and trefoil (Z3,3) between the iTrace and OPD Scan (p<0.001, p=0.01, p<0.001) for the same pupil diameter of 4 mm. At a pupil diameter of 6 mm, the two instruments showed a similar number of total aberrations. Aberrations of the internal optics showed significant differences in the mean values of total RMS, spherical aberration (Z4,0), and coma (Z3,-1) between the two devices (p<0.001, p=0.01, p<0.001). CONCLUSIONS: The iTrace and OPD Scan showed the largest number of differences for aberrations of internal optics rather than total aberrations for both pupil diameters. These results suggest that in healthy eyes, the two aberrometers may vary in some details. The aberrometers showed more agreement at a pupil diameter of 6 mm compared to 4 mm.
Adult ; Diagnostic Techniques, Ophthalmological/*instrumentation ; Humans ; Pupil/physiology ; Refractive Errors/*diagnosis ; Reproducibility of Results

PURPOSE: Pupillary examination is an important objective method to diagnose lesions of the anterior visual pathways. However, errors and faults may easily alter the interpretation and value of the test as it is highly dependent on the examiner's skills. Therefore, we tried to develop a pupillography which is independent of the examiner. METHODS: Hardware composed of a binocularly measuring instrument adapted for an infrared charge coupled device (CCD) was developed. Two arrays of infrared light emitting diodes (LED) were supplied in front of each of the subject's eyes. A microcontroller to modulate these LED was developed, as was software to save and analyze the pupil images. The hardware was able to deliver a light to either eye or to both eyes, and to change the time, frequency, and intensity of the stimulus. The software automatically analyzed the pupil size and location by image processing. Pupil size was calculated continuously. After artifact elimination, the response amplitudes of the pupils were determined for the right and left pupils. RESULTS: Pupillary images of size 320 x 240, at 30 frames/second, were saved and processed to evaluate the change of the actual pupil size and the velocity of pupillary response. CONCLUSIONS: A pupillography to measure, save and analyze the pupillary response using image processing was developed. Further detailed clinical studies with a large number of patients will be required to validate this new method.
Diagnostic Techniques, Ophthalmological/*instrumentation ; Equipment Design ; Humans ; *Image Processing, Computer-Assisted ; *Reflex, Pupillary

An instrument for subjective measurement of tonic accommodation has been established based on the Badal system and Scheiner principle. The results of tonic accommodation between subjective measurement and objective measurement have no significant difference. Its establishment is important for the measurement of accommodation parameter in the myopia research center.
Accommodation, Ocular ; physiology ; Diagnostic Techniques, Ophthalmological ; instrumentation ; Humans ; Optometry ; instrumentation ; methods ; Refractometry ; instrumentation ; methods ; Visual Acuity

According to the mechanism of spectral domain optical coherence tomography, this paper gives a design and development of a practical OCT imaging device based on slit-lamp microscopic widely-used in ophthalmology. The paper details the device's architecture and three key points in design: communication between PC and MCU, how to design modules of fixation lamp and reference arm and anti-interference measures.
Diagnostic Techniques, Ophthalmological ; instrumentation ; Equipment Design ; Tomography, Optical Coherence ; instrumentation ; methods

This paper combined the coded excitation with the technique of ophthalmic high-frequency ultrasonic imaging, and raised a new high-velocity data detection and signal processing method. 16 bit Golay complementarity sequences were produced by FPGA, which excited the probe to produce ultrasonic waves. Data detection circuit achieved the digitalized of the 15 MHz high-frequency ultrasonic echo signals in real time. Sampling rate was 120MHz, and sampling bit was 14 bit. Decoded compression arithmetic was realized by FPGA in real time, in which A code compression was alternated with B code compression. The return echo was correlated with the corresponding decode filter A and filter B respectively, and then the echo was delayed and summed to complete the decoding process. The experiment indicated that coded excitation can effectively increase the range of mainlobe and decrease the range of sidelobe. This technique can effectively raise the signal-to-noise ratio, and has significant research value in advancing the ophthalmic ultrasonic image quality and raising the safety of the equipment.
Data Compression ; Diagnostic Techniques, Ophthalmological ; Signal Processing, Computer-Assisted ; Ultrasonography ; methods

INTRODUCTIONTo evaluate whether eyes with longer axial lengths are associated more often with clinically significant cataracts than eyes with shorter axial lengths.

MATERIAL AND METHODSCharts of consecutive patients who underwent cataract surgery by 4 resident surgeons at Los Angeles County Hospital from July 2001 through May 2002 were retrospectively reviewed. Those patients whose axial lengths were significantly different between the 2 eyes (>or=0.30 mm) and who had no pathology (other than cataracts) affecting visual acuity were included in the study. The 2 eyes in each patient were compared for preoperative best-corrected visual acuity and severity of cataracts.

RESULTSThirty-four of 353 patients had interocular axial length differences of at least 0.3 mm and were included in this study. Thirty-one patients had worse, 1 had equal, and 2 had better preoperative vision in the eye with longer versus the shorter axial length. Fourteen patients had more severe, 11 had the same, and 1 had less severe posterior subcapsular cataract (PSC) in the eye with longer axial length. In 8 patients, PSC severity could not be assessed due to obscuring nuclear sclerosis. Twenty-four patients had more severe, 7 patients had equal, and 3 patients had less severe nuclear sclerosis in the longer eye. Overall, longer axial lengths correlated with worse visual acuity, posterior subcapsular cataracts, and nuclear sclerosis. Diabetic status did not affect the correlation. The correlations were stronger with greater axial length asymmetry.

CONCLUSIONSEyes with longer axial lengths have a higher prevalence of cataracts.

PURPOSE: To determine the efficacy and safety of the dark-room prone-position test (DRPT) for intermittent angle closure (IAC) and to investigate the correlation between A-scan ultrasound biometric measurements and the results of DRPT. METHODS: Medical records were reviewed of 37 eyes in 24 patients who were diagnosed with IAC and received DRPT. The increase of intraocular pressure (IOP) induced by DRPT and the results from A-scan ultrasound biometric measurements were obtained. An increase in IOP of at least 8 mmHg from baseline was considered a positive result for DRPT. Associations between the increase of IOP induced by DRPT and the parameters of A-scan biometry were tested by linear regression analysis. RESULTS: The DRPT results were positive in 28 eyes of 19 patients. After DRPT, the IOP returned to near-baseline levels within 2 hours in all patients; some patients were treated with anti-glaucoma eye drops. Lens thickness was significantly correlated with the amount of IOP elevation induced by DRPT (r=0.338, p=0.041). CONCLUSIONS: DRPT is a safe and effective test in patients with IAC. DRPT can be used effectively to make a concrete diagnosis of IAC. Lens thickness appears to be associated with a positive response to DRPT.
Adult ; Aged ; *Darkness ; *Diagnostic Techniques, Ophthalmological/standards ; Female ; Glaucoma, Angle-Closure/*diagnosis ; Humans ; Male ; Middle Aged ; *Prone Position ; Ultrasonography