Ophthalmic System Research Articles

Femtosecond Laser- Assisted Customized CAIRS In Keratoconus Patients After ICRS Explantation: A Prospective Case Series: Customized CAIRS in post ICRS extrusion keratoconus patients.

To investigate the effectiveness and safety of customized femtosecond laser-assisted corneal allogenic intrastromal ring segments (CAIRS) implantation in keratoconus patients with a history of intrastromal corneal ring segment (ICRS) explantation. Sorocaba Eye Hospital (Hospital Oftalmológico de Sorocaba - HOS), Sorocaba, Brazil. Prospective case series. We included eight keratoconus patients with stable disease and with history of ICRS explantation at least six months before the inclusion in the study. Patients were excluded if presenting any other ocular pathology. Customized CAIRS was produced and implanted using femtosecond laser LDV Z8 (Ziemer Ophthalmic Systems AG, Port, Switzerland). Patients were followed-up for six months. The mean reduction of the maximum, mean, and steep central keratometry was 3.03 ± 1.35 diopters (D) (p =0.01), 2.88 ± 2.51 D (p=0.02), and 2.41 ± 2.72 D (p=0.04), respectively. The mean spherical equivalent and refractive astigmatism reduced 6.28 ± 2.71 D (p =0.01), and 1.62 ± 2.83 D (p=0.16). All eyes, but one gained two or more lines of best spectacle corrected visual acuity (BSCVA).Additionally, five patients achieved a BSCVA of 20/40 or better. No intra or post-operative complications were observed. Customized femtosecond laser assisted CAIRS may be an effective and safe option for visual rehabilitation in keratoconus patients with previous ICRS explantation.

Ultrafast adaptive optics for imaging the living human eye

Adaptive optics (AO) is a powerful method for correcting dynamic aberrations in numerous applications. When applied to the eye, it enables cellular-resolution retinal imaging and enhanced visual performance and stimulation. Most ophthalmic AO systems correct dynamic aberrations up to 1−2 Hz, the commonly-known cutoff frequency for correcting ocular aberrations. However, this frequency may be grossly underestimated for more clinically relevant scenarios where the medical impact of AO will be greatest. Unfortunately, little is known about the aberration dynamics in these scenarios. A major bottleneck has been the lack of sufficiently fast AO systems to measure and correct them. We develop an ultrafast ophthalmic AO system that increases AO bandwidth by ~30× and improves aberration power rejection magnitude by 500×. We demonstrate that this much faster ophthalmic AO is possible without sacrificing other system performances. We find that the discontinuous-exposure AO-control scheme runs 32% slower yet achieves 53% larger AO bandwidth than the commonly used continuous-exposure scheme. Using the ultrafast system, we characterize ocular aberration dynamics in six clinically-relevant scenarios and find their power spectra to be 10−100× larger than normal. We show that ultrafast AO substantially improves aberration correction and retinal imaging performance in these scenarios compared with conventional AO.

Intraoperative Optical Coherence Tomography (OCT)-Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD)

We describe retrospectively the indications and outcomes of nine patients who present with varying degrees of deep posterior stromal scarring or endothelial failure following deep anterior lamellar keratoplasty (DALK). These patients underwent a surgical strategy coined Intraoperative Optical Coherence Tomography Guided Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty (iFAD). This strategy can be used to address suboptimal visual outcomes following primary DALK. Patients undergoing iFAD first had femtosecond laser-assisted trephination of the underlying posterior lamella using the liquid keratoplasty system on the Femto LDV Z8 platform (Zeimer Ophthalmic Systems AG, Port, Switzerland). A Descemet Membrane Endothelial Keratoplasty (DMEK) graft was subsequently transplanted in place of the removed lamella. Out of nine cases, major indications for seven included post-infective, blepharokeratoconjunctivitis (BKC) and deep stromal scarring related to stromal dystrophy. The remaining two had endothelial failure following primary DALK. The main benefits of this surgical approach are (1) Utilization of integrated real-time iOCT on the femtosecond laser platform allows for precise calibration of a wide range of vertical posterior trephination depths (96–329 microns) from the endothelial surface. (2) Femtosecond laser trephination utilizing a non-applanation liquid interface preserves trephination geometries and maximises precision-based surgical outcomes. (3) iFAD is a viable and straightforward technique for surgeons addressing patients who might otherwise require complex surgery to address residual deep stromal scars post-DALK.

Keratorefractive Lenticule Extraction Using the Ziemer FEMTO LDV Z8 Platform (CLEAR): One-Year Results.

To present the outcomes and detail the surgical procedure employed in the initial 102 eyes treated with keratorefractive lenticule extraction (KLEx) using the FEMTO LDV Z8 platform (Ziemer Ophthalmic Systems). This was a retrospective analysis of 102 eyes of 53 patients treated with KLEx at the American University of Beirut Medical Center. Visual, refractive, topographic, and aberrometric parameters were evaluated 1 week and 1, 3, 6, and 12 months postoperatively. Mean preoperative spherical equivalent refraction (SEQ) was -4.11 ± 1.82 diopters (D) (range: -10.00 to -1.625 D) and mean preoperative cylinder was -0.75 ± 0.65 D (range: -3.00 to 0.00 D). Postoperatively, the mean SEQ was 0.06 ± 0.54 D (range: -2.88 to +1.00 D) at 1 week and -0.04 ± 0.26 D at 12 months and was within ±0.50 D in 95.6% and ±1.00 D in 100% of eyes. A total of 96.7% of eyes had an uncorrected distance visual acuity (UDVA) of 20/20 at 12 months postoperatively. Fifty percent gained one or more lines of corrected distance visual acuity (CDVA), 5 eyes (5.4%) lost one line, and none lost two or more lines. No suction losses were encountered and all extracted lenticules were intact without tears. The application of KLEx using the FEMTO LDV Z8 platform yields safe and effective outcomes, aligning comparably with established modes of lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis procedures previously employed and accepted within the field of refractive surgery. [J Refract Surg. 2024;40(11):e898-e905.].

Comparison and analysis of ophthalmic resources and service ability in Shanxi Province in 2014 and 2021

Objective: To compare and analyze the ophthalmic resources and service ability in Shanxi Province in 2014 and 2021, and to provide reference for the development planning of ophthalmology and eye care. Methods: In this cross-sectional study, a questionnaire survey was conducted among all ophthalmic institutions registered in the health administrative department in 11 cities of Shanxi Province by the end of 2014 and 2021 by using the National Ophthalmology Competency Resource Questionnaire (compiled by the Medical Administration and Hospital Authority of the National Health and Wellness Commission). The basic situations of ophthalmic institutions in 2014 and 2021, as well as the human resources, ophthalmic equipment configuration, technology and medical service capabilities, were recorded and compared. The chi-square test was used for statistical analysis. Results: A total of 270 questionnaires for 2014 were collected from 270 ophthalmic institutions, and 292 questionnaires for 2021 from 292 ophthalmic institutions. The institution categories in 2014 (197 general hospitals, 31 eye hospitals and 42 others) were statistically different from those in 2021 (182 general hospitals, 45 eye hospitals and 65 others) (P<0.05). The proportion of doctors with senior titles in ophthalmic institutions increased from 25.5% (346/1 358) in 2014 to 41.7% (580/1 391) in 2021, the proportion of senior technicians increased from 9.4% (14/148) to 25.3% (110/435), the proportion of doctors with junior titles decreased from 42.1% (572/1 358) to 26.5% (369/1 391), and the proportion of junior technicians decreased from 45.3% (67/148) to 39.1% (170/435). There was a significant difference in the distribution of professional titles between doctors and technicians in ophthalmic institutions (P<0.05). The number of doctors (130 to 28), nurses (152 to 50), technicians (33 to 11) and full-time optometrists (44 to 12) in the first-class ophthalmic institutions decreased, the increase of equipment with the ophthalmic A-ultrasound scan system, fundus camera and coherent optical tomography system (35.1%, 28.9% and 25.4%; P<0.05) ranked the top three, and the increase of performing the phacoemulsification procedure, intraocular lens implantation, intravitreal injection and iris surgery (30.2%, 24.7% and 20.7%; P<0.05) ranked the top three in 2021 as compared to 2014. Conclusions: The resources and service ability of ophthalmology in Shanxi Province developed in 2021 in comparison with 2014. However, there were some problems, such as changes in the type and structure of eye institutions, unreasonable proportions of professional titles, insufficient human resources in primary ophthalmic institutions, and slow improvement in the allocation of ophthalmology equipment and technical capabilities.

A multi-class fundus disease classification system based on an adaptive scale discriminator and hybrid loss

Fundus images are crucial in the observation and detection of ophthalmic diseases. However, detecting multiple ophthalmic diseases from fundus images using deep learning techniques is a complex and challenging task One challenge is the complexity of fundus disease structures, which leads to low detection accuracy. Another challenge is the class imbalance problem common in multi-label image classification, which increases the difficulty of algorithm training and evaluation. To address these issues, this study leverages deep learning to propose an ophthalmic disease classification system. We first employ ResNet50 as the backbone network to extract image features, and then use our designed multi-dimensional attention module and adaptive scale discriminator to enhance the network's ability to detect disease features. During training, we innovatively propose a hybrid loss function method to improve the detection capability on imbalanced data. Finally, we conducted experiments on the ODRI-5K dataset with the proposed classification system. In the test set, our method achieved an AUC of 98.53 and an F1-score of 89.73. This result fully demonstrates the excellent disease classification capability of our method. In summary, the multi-label fundus image disease classification system we proposed exhibits outstanding recognition capability, providing an effective solution for the diagnosis of multi-label fundus image diseases.

Information-extreme machine learning of an ophthalmic diagnostic system with a hierarchical class structure

The paper considers the method of hierarchical information-extreme machine learning for the system of ophthalmic diagnosis of eye pathology. Since the proposed method is developed within the framework of a functional approach to modeling the cognitive processes of natural intelligence, it, unlike neuro-like structures, acquires the properties of flexibility when retraining a diagnostic system and requires an order of magnitude fewer image samples. In addition, the decision rules based on the results of machine learning within the geometric approach in the form of a binary hierarchical structure of recognition classes ensure their practical invariance to the multidimensionality of both the space of diagnostic features and the alphabet of recognition classes. The modified Kullback-Leibler information measure, which is considered as a function of the accuracy of classification solutions, is chosen as a criterion for optimizing the parameters of the machine learning system for diagnosing eye pathologies. A hierarchical information-extreme machine learning algorithm for an ophthalmic diagnostic system for six eye pathologies was developed and programmatically implemented. Based on the results of functional diagnostics, it has been experimentally proved that the constructed decision rules are error-free according to the training matrices of recognition classes of each level of the constructed binary hierarchical structure.

In vivo screening of flavonoid compounds revealed quercetin as a potential drug to improve recovery of angiostrongyliasis after albendazole treatment.

Human angiostrongyliasis, caused by consuming the larva stage of Angiostrongylus cantonensis, is an infectious disease involving the central nervous system (CNS) and ophthalmic system. Current treatment of angiostrongyliasis involves albendazole accompanied by analgesics and corticosteroids. However, long-term use of corticosteroids may lead to significant adverse effects. In the current study, we screened through different potentially effective flavonoid compounds and identified quercetin as an effective anti-inflammatory agent in an angiostrongyliasis mouse model. Our results identified that quercetin may reverse the neurological defects in mice with angiostrongyliasis. The brain pathology and inflammatory status were also improved by albendazole-quercetin co-therapy. Further analysis showed that albendazole-quercetin co-therapy had a better therapeutic effect than albendazole or quercetin monotherapy. This therapeutic effect was achieved by inhibiting the brain inflammasome activation and apoptosis. Albendazole-quercetin co-therapy also leads to the inhibition of brain IL-5, possibly leading to improved pathology. Our results here proved that quercetin may serve as a potential adjuvant drug in treating human angiostrongyliasis.

MobilenetV2-RC: A lightweight network model for retinopathy classification in retinal OCT images

Abstract Retinopathy is an important ophthalmic disease that causes blindness in the elderly population. With the global old peoples increasing, the ophthalmic healthcare system is more and significant to pre-diagnosis. Optical Coherence Tomography (OCT) is considered the gold standard for ophthalmic treatment and diagnosis. OCT technologies and equipment continue to develop towards the intelligence and convenience for requirements of rapid diagnosis in the remote and poverty-stricken areas. We proposed an improved MobilenetV2 lightweight model for retinopathy classification (MobilenetV2-RC), which incorporates Spatial and Channel Reconstruction Convolution (SCConv) and the improved Convolutional Block Attention Module (CBAM) attention mechanism into the framework. Not only can it effectively limit feature redundancy to reduce model parameters, but also enhance the ability of feature representation to improve classification accuracy. The parameters of the proposed model are only 1.96 M with an overall accuracy of 98.96%, which is higher 3.32% than the original MobilenetV2. Compared with ResNet18, InceptionV3, and VGG16_BN, the overall accuracy is increased by 4.6%, 6.3%, and 3.9%, respectively. The test results of UCSD and Duke open-source datasets are more remarkable. Experimental results show that our proposed algorithm has strong reliability and generalization for the accurate classification of retinopathy, and a greater application prospect in the intelligent diagnosis of ophthalmology and mobile detection terminals.&amp;#xD;

ChatFFA: An ophthalmic chat system for unified vision-language understanding and question answering for fundus fluorescein angiography

Existing automatic analysis of fundus fluorescein angiography (FFA) images faces limitations, including a predetermined set of possible image classifications and being confined to text-based question-answering (QA) approaches. This study aims to address these limitations by developing an end-to-end unified model that utilizes synthetic data to train a visual question-answering model for FFA images. To achieve this, we employed ChatGPT to generate 4,110,581 QA pairs for a large FFA dataset, which encompassed a total of 654,343 FFA images from 9,392 participants. We then fine-tuned the Bootstrapping Language-Image Pre-training (BLIP) framework to enable simultaneous handling of vision and language. The performance of the fine-tuned model (ChatFFA) was thoroughly evaluated through automated and manual assessments, as well as case studies based on an external validation set, demonstrating satisfactory results. In conclusion, our ChatFFA system paves the way for improved efficiency and feasibility in medical imaging analysis by leveraging generative large language models.

Association between HDL cholesterol with diabetic retinopathy in diabetic patients: a cross-sectional retrospective study

ObjectiveDiabetic patients are often comorbid with dyslipidemia, however, the relationship between high-density lipoprotein cholesterol(HDL-C) and diabetic retinopathy (DR) in the adult diabetic population remains to be fully elucidated.The aim of this study is to evaluate the associations between HDL-C and DR in the United States adults with diabetes.MethodsA total of 1708 participants from the National Health and Nutrition Examination Survey (NHANES) 2005–2008 were enrolled in the present study. Fundus images of all study subjects were captured and evaluated using a digital camera and an ophthalmic digital imaging system, and the diagnosis of DR was made by the severity scale of the Early Treatment Diabetic Retinopathy Study (ETDRS).Roche Diagnostics were used to measure serum HDL-C concentration. The relationship of DR with HDL-C was investigated using multivariable logistic regression. The potential non-line correlation was explored with smooth curve fitting approach.ResultsThe fully-adjusted model showed that HDL-C positively correlated with DR(OR:1.69, 95%CI: 1.25–2.31).However, an inverted U-shaped association between them was observed by applying the smooth curve fitted method. The inflection point of HDL-C(1.99mmol/l) was calculated by utilizing the two-piecewise logistic regression model. In the subgroup analysis, the inverted U-shaped nonlinear correlation between HDL-C and DR was also found in female, Non-Hispanic White, and lower age groups.ConclusionOur study revealed an inverted U-shaped positive relationship between HDL-C and DR.The findings may provide us with a more comprehensive understanding of the association between HDL-C and DR.

Megahertz multi-parametric ophthalmic OCT system for whole eye imaging

An ultrahigh-speed, wide-field OCT system for the imaging of anterior, posterior, and ocular biometers is crucial for obtaining comprehensive ocular parameters and quantifying ocular pathology size. Here, we demonstrate a multi-parametric ophthalmic OCT system with a speed of up to 1 MHz for wide-field imaging of the retina and 50 kHz for anterior chamber and ocular biometric measurement. A spectrum correction algorithm is proposed to ensure the accurate pairing of adjacent A-lines and elevate the A-scan speed from 500 kHz to 1 MHz for retinal imaging. A registration method employing position feedback signals was introduced, reducing pixel offsets between forward and reverse galvanometer scanning by 2.3 times. Experimental validation on glass sheets and the human eye confirms feasibility and efficacy. Meanwhile, we propose a revised formula to determine the “true” fundus size using all-axial length parameters from different fields of view. The efficient algorithms and compact design enhance system compatibility with clinical requirements, showing promise for widespread commercialization.

Comparative study of the three-dimensional perception of videos recorded on a "Do it yourself" three-dimensional recording assembly versus the conventional recording system.

To develop an indigenous "Do it yourself" (DIY) three-dimensional (3D) ophthalmic surgery recording system and validate the perception of stereopsis using it. A cross-sectional survey of practicing ophthalmologists with post-postgraduation experience of at least 5 years for perception of stereopsis for three different surgeries was performed; cataract, retinal detachment, and intravitreal drug injection were recorded on DIY assembly, viewed on VRBOX and using laptop videos and pseudo 3 d videos as control. The laptop videos and 3D VR Box videos received higher ratings for stereopsis than the pseudo 3D videos. The parameters that received significantly higher ratings on the 3D VR Box viewing were instrument's position relative to the ocular surface in cataract surgery, anterior chamber depth during capsular staining, ophthalmic visco-surgical device injection, capsulorhexis, phaco tunnel depth, movement of nuclear fragments in the anterior chamber, and intra-ocular lens tilt in the capsular bag during cataract surgery ( P < 0.05). In scleral buckling surgery, the parameters that were significantly rated higher on VR Box were globe contour, separation of the scleral plane from muscle, and explant plane ( P < 0.05). Furthermore, the depth of the needle in the vitreous cavity while administering intravitreal drug injection was also rated significantly higher on VR Box ( P < 0.05). However, the ratings for the depth of corneal incision, depth of scleral incision, overall color, and overall quality were not different statistically when compared between laptop and VR Box viewing. DIY 3D recording assembly offers a superior means of appreciating depth at various stages of cataract surgery, scleral buckling, and intravitreal drug injection when compared to laptop viewing and can serve as an effective tool for skill transfer.

Causes and management of sight threatening complications of dermal filler injections: A review.

Injectable dermal fillers continue to increase in popularity in aesthetic medicine. Although rare, vision loss secondary to filler injections is a devastating complication associated with a poor visual prognosis. The mechanism for vision loss is thought to be related to retrograde embolization of the dermal filler from peripheral vessels in the face into the ophthalmic arterial system. Early recognition and prompt management are essential if vision is to be salvaged. The use of retrobulbar hyaluronidase is still contentious, however when administered by a specialist, this treatment gives the best chance at visual recovery and should be considered for all cases.

Using Total Corneal Astigmatism With Femtosecond Laser Cataract Surgery and Arcuate Keratotomy(ies) to Treat Low Amounts of Astigmatism.

The aim of this study was to evaluate outcomes using total corneal astigmatism (TCA) to calculate arcuate keratotomy(ies) (AK) parameters performed with femtosecond laser-assisted cataract surgery to reduce low corneal astigmatism. Patients who had femtosecond laser-assisted cataract surgery and AK with 0.50 diopter (D) to 1.30 D of TCA were included. Exclusion criteria were intraoperative complications, preexisting corneal surgery, and comorbidities that might adversely affect outcomes. Corneal tomography (Galilei G4, Zeimer Ophthalmic Systems AG) was performed preoperatively and 1 month postoperatively. TCA was input into the Donnenfeld limbal relaxing incisions nomogram to calculate the AK parameters. Preoperative and postoperative tomographic and subjective refractive measurements were compared. The Alpins method for vector analysis evaluated results. Eighty-two eyes of 82 patients were included. Mean preoperative TCA was significantly reduced from 0.80 ± 0.19 D to 0.51 D ± 0.26 D ( P < 0.001). Preoperative posterior corneal astigmatism, -0.28 ± 0.13 D, was unchanged, postoperative posterior corneal astigmatism, -0.28 ± 0.14 D ( P = 0.653). Target-induced astigmatism arithmetic mean (0.82 ± 0.21 D) was greater than that of the surgically induced astigmatism (0.70 ± 0.40 D), resulting in an arithmetic mean difference vector of 0.51 ± 0.27 D with a summated mean at 0.16 D at 20 degrees. The correction index was 0.87, indicating undercorrection. Angle of error arithmetic mean, -1.27 ± 23.27 degrees, indicated good alignment. Inputting TCA for calculation of femtosecond laser AK parameters can reduce low amounts of preoperative corneal astigmatism, thereby improving uncorrected vision.

Head stabilization apparatus for high-resolution ophthalmic imaging.

Head movement must be stabilized to enable high-quality data collection from optical instrumentation such as eye trackers and ophthalmic imaging devices. Though critically important for imaging, head stabilization is often an afterthought in the design of advanced ophthalmic imaging systems, and experimental devices often adapt used and/or discarded equipment from clinical devices for this purpose. Alternatively, those seeking the most stable solution possible, including many users of adaptive optics ophthalmoscopy systems, utilize bite bars. Bite bars can provide excellent stability but are time consuming to fabricate, decreasing imaging efficiency, and uncomfortable for many patients, especially the elderly and/or those with prosthodontics such as dentures who may refuse participation in a study that requires one. No commercial vendors specifically offer head mount solutions for experimental ophthalmic imaging devices, resulting in nearly every custom device having a different solution for this commonly encountered problem. Parallelizing the head stabilization apparatus across different custom devices may improve standardization of experimental imaging systems for clinical trials and other multicenter investigations. Here we introduce a head mount design for ophthalmic imaging that is modular, adjustable, and customizable to the constraints of different experimental imaging configurations. The three points of head contact in our solution provide excellent stabilization across a range of head sizes and shapes from small children to adults, and the ease of adjustment afforded by our design minimizes the time to get participants stabilized and comfortable.

A review of neuro-ophthalmic sequelae following COVID-19 infection and vaccination.

It has become increasingly clear that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect most organs in the human body, including the neurologic and ophthalmic systems. Vaccination campaigns have been developed at rapid pace around the world to protect the population from the fast-mutating virus. This review seeks to summarise current knowledge of the neuro-ophthalmic manifestations of both COVID-19 infection and vaccination. Electronic searches for published literature were conducted using EMBASE and MEDLINE on the 30th of July 2023. The search strategy comprised of controlled vocabulary and free-text synonyms for the following terms in various combinations: "coronavirus, COVID-19, SARS-CoV-2, 2019-nCoV, vaccination, vaccine, immunisation and neuro-ophthalmology". No time range limits were set for the literature search. Published English abstracts for articles written in a different language were screened if available. A total of 54 case reports and case series were selected for use in the final report. 34 articles documenting neuro-ophthalmic manifestations following COVID-19 infection and 20 articles with neuro-ophthalmic complications following COVID-19 vaccination were included, comprising of 79 patients in total. The most commonly occurring condition was optic neuritis, with 25 cases following COVID-19 infection and 27 cases following vaccination against COVID-19. The various COVID-19 vaccines that are currently available are part of the global effort to protect the most vulnerable of the human population. The incidence of neuro-ophthalmic consequences following infection with COVID-19 is hundred-folds higher and associated with more harrowing systemic effects than vaccination against the virus.

COVID-19 pathogenesis.

The pathogenesis of COVID-19 involves a complex interplay between host factors and the SARS-CoV-2 virus, leading to a multitude of clinical manifestations beyond the respiratory system. This chapter provides an overview of the risk factors, genetic predisposition, and multisystem manifestations of COVID-19, shedding light on the underlying mechanisms that contribute to extrapulmonary manifestations. The chapter discusses the direct invasion of SARS-CoV-2 into various organs as well as the indirect mechanisms such as dysregulation of the renin-angiotensin-aldosterone system (RAAS), immune response dysfunctions within the innate and adaptive immune systems, endothelial damage, and immunothrombosis. Furthermore, the multisystem manifestations of COVID-19 across different organ systems, including the cardiovascular, renal, gastrointestinal, hepatobiliary, nervous, endocrine and metabolic, ophthalmic, ear-nose-throat, reproductive, hematopoietic, and immune systems are discussed in detail. Each system exhibits unique manifestations that contribute to the complexity of the disease.

Development of a High‐Frequency Ophthalmic Real‐Time Ultrasound Imaging System Based on a 20 MHz Annular‐Array Transducer

Objective. Ophthalmic ultrasound imaging is a widely used diagnostic method for examining ophthalmic diseases in the clinic. A single‐element transducer is adopted in the traditional ophthalmic ultrasound imaging systems. Although full depth focusing can be achieved using a linear‐array transducer, it is unsuitable for ophthalmic imaging due to its inability to be tightly coupled to the eyeball and its higher cost. Annular‐array‐based systems provide an alternative, striking a balance between image quality and cost. Methods. Here, we present a newly developed high‐frequency ophthalmic real‐time ultrasound imaging system based on an annular‐array transducer. This system uses a custom‐made five‐element, 20 MHz annular‐array transducer encapsulated in a stainless steel housing and mounted in a commercially available handheld mechanical probe designed specifically for clinical ophthalmic imaging. The system uses a printed circuit board scheme and FPGA as the core to complete the hardware system design and realize the ultrasonic echo signal processing and system timing management. Full depth dynamic focusing of each scanning beam was achieved by designing the transmit and receive beamforming. Combined with advanced integrated circuits, the miniaturization and low cost of the overall system are realized. Results. Extensive tests, including hardware, wire phantom, and tissue mimicking phantom measurements, were conducted to demonstrate good performance of the system. The results showed that the designed system can effectively improve the imaging resolution and enhance the depth of field of the image, particularly reducing the blind area of the near‐field. Conclusion. The high‐frequency ophthalmic real‐time ultrasound imaging system based on an annular‐array transducer meets the needs of clinical diagnosis and has a good clinical application prospect.

In situ Gel: A Promising Ocular Drug Delivery System

The eye is a vital organ, faces challenges in drug delivery with traditional ophthalmic formulations due to the rapid loss of medications before reaching the cornea. This review explores novel drug delivery systems for ocular administration, emphasizing innovative dosage forms, i.e., in situ gels. This system aims to prolong drug contact time in the eyes, overcoming bioavailability issues associated with conventional delivery methods. The article further delves into in situ gelation approaches, highlighting pH-triggered, temperature-dependent, and ion-activated systems. It explores the use of excipients like polymers and solubilizing agents in the preparation of in-situ gels. The frequently used polymers and their applications in ocular drug delivery are detailed. Studies on the incorporation of nanoparticles in this gelling system for ocular drug delivery. Methodologies for evaluating in situ gels, including pH determination, rheological studies, drug content analysis, in vitro gelation, accelerated stability studies, and FTIR analysis, are presented. The advantages &amp; applications of in situ gels are discussed, along with its limitations. The review concludes by emphasizing the benefits of novel ocular drug delivery systems, particularly in situ ophthalmic systems, which offer controlled and sustained drug release, and the future perspective of in situ gel. These advancements hold promise for more effective therapeutic outcomes in the field of ocular drug delivery.