Intense pulsed light therapy for ocular surface diseases.

Intense pulsed light (IPL) is a non-laser, high-intensity light source that has been shown to play a valuable role in dermatology and has been adopted in ophthalmology for treating meibomian gland dysfunction (MGD). In this review, we discuss the mechanism of action of IPL, including its benefits in ophthalmology. IPL therapy has been shown to improve tear film stability, meibomian gland (MG) function, and subjective symptoms of ocular dryness in MGD patients. Moreover, emerging evidence suggests that IPL therapy is beneficial for other ocular surface diseases, such as blepharitis and chalazia. Hence, it can be inferred that IPL has potential as a therapeutic modality in future applications. Large clinical and experimental trials are needed to exploit the full potential of IPL as a treatment for recurrent chalazia, Sjögren's syndrome, and other causes of dry eye disease (DED). This paper reviews the published literature related to the application of IPL for treating ocular surface diseases.

In Vivo Evaluation of Corneal Biomechanics Following Cross-Linking Surgeries Using Optical Coherence Elastography in a Rabbit Model of Keratoconus.

Purpose: Validation of the feasibility of novel acoustic radiation force optical coherence elastography (ARF-OCE) for the evaluation of biomechanical enhancement of the in vivo model of keratoconus by clinical cross-linking (CXL) surgery. Methods: Twelve in vivo rabbit corneas were randomly divided into two groups. Both groups were treated with collagenase type II, and a keratoconus model was obtained. Then, the two groups were treated with CXL procedures with different irradiation energy of 15 J and 30 J (CXL-15 J and CXL-30 J, respectively). An ARF-OCE probe with an ultrasmall ultrasound transducer was used to detect the biomechanical properties of cornea. An antisymmetric Lamb wave model was combined with the frequency dispersion relationship to achieve depth-resolved elastography. Results: Compared with the phase velocity of the Lamb wave in healthy corneas (approximately 3.96 ± 0.27 m/s), the phase velocity of the Lamb wave was lower in the keratoconus region (P < 0.05), with an average value of 3.12 ± 0.12 m/s. Moreover, the corneal stiffness increased after CXL treatment (P < 0.05), and the average phase velocity of the Lamb wave was 4.3 ± 0.19 m/s and 4.54 ± 0.13 m/s after CXL-15 J and CXL-30 J treatment. Conclusions: The Young's moduli of the keratoconus regions were significantly lower than the healthy corneas. Moreover, the Young's modulus of the keratoconus regions was significantly higher after CXL-30 J treatment than after CXL-15 J treatment. We demonstrated that the ARF-OCE technique has great potential in screening keratoconus and guiding clinical CXL treatment. Translational Relevance: This work accelerates the clinical translation of OCE systems using ultrasmall ultrasound transducers and is used to guide CXL procedures.

Supershear Rayleigh wave imaging for quantitative assessment of biomechanical properties of brain using air-coupled optical coherence elastography.

Recently, supershear Rayleigh waves (SRWs) have been proposed to characterize the biomechanical properties of soft tissues. The SRWs propagate along the surface of the medium, unlike surface Rayleigh waves, SRWs propagate faster than bulk shear waves. However, their behavior and application in biological tissues is still elusive. In brain tissue elastography, shear waves combined with magnetic resonance elastography or ultrasound elastography are generally used to quantify the shear modulus, but high spatial resolution elasticity assessment in 10 µm scale is still improving. Here, we develop an air-coupled ultrasonic transducer for noncontact excitation of SRWs and Rayleigh waves in brain tissue, use optical coherent elastography (OCE) to detect, and reconstruct the SRW propagation process; in combing with a derived theoretical model of SRWs on a free boundary surface, we quantify the shear modulus of brain tissue with high spatial resolution. We first complete validation experiments using a homogeneous isotropic agar phantom, and the experimental results clearly show the SRW is 1.9649 times faster than the bulk shear waves. Furthermore, the propagation velocity of SRWs in both the frontal and parietal lobe regions of the brain is all 1.87 times faster than the bulk shear wave velocity. Finally, we evaluated the anisotropy in different brain regions, and the medulla oblongata region had the highest anisotropy index. Our study shows that the OCE system using the SRW model is a new potential approach for high-resolution assessment of the biomechanical properties of brain tissue.

Noncontact longitudinal shear wave imaging for the evaluation of heterogeneous porcine brain biomechanical properties using optical coherence elastography.

High-resolution quantification of heterogeneous brain biomechanical properties has long been an important topic. Longitudinal shear waves (LSWs) can be used to assess the longitudinal Young's modulus, but contact excitation methods have been used in most previous studies. We propose an air-coupled ultrasound transducer-based optical coherence elastography (AcUT-OCE) technique for noncontact excitation and detection of LSWs in samples and assessment of the nonuniformity of the brain's biomechanical properties. The air-coupled ultrasonic transducer (AcUT) for noncontact excitation of LSWs in the sample has a center frequency of 250 kHz. Phase-resolved Doppler optical coherence tomography (OCT) was used to image and reconstruct the propagation behavior of LSWs and surface ultrasound waves at high resolution. An agar phantom model was used to verify the feasibility of the experimental protocol, and experiments with ex vivo porcine brain samples were used to assess the nonuniformity of the brain biomechanical properties. LSWs with velocities of 0.83 ± 0.11 m/s were successfully excited in the agar phantom model. The perivascular elastography results in the prefrontal cortex (PFC) of the ex vivo porcine brains showed that the Young's modulus was significantly higher in the longitudinal and transverse directions on the left side of the cerebral vessels than on the right side and that the Young's modulus of the PFC decreased with increasing depth. The AcUT-OCE technique, as a new scheme for LSW applications in in vivo elastography, can be used for noncontact excitation of LSWs in brain tissue and high-resolution detection of heterogeneous brain biomechanical properties.

Novel treatment of chalazion using light-guided-tip intense pulsed light.

We assessed the effectiveness of light-guided-tip intense pulsed light (IPL) with meibomian gland expression (MGX) in chalazion treatment. Ninety-five eyes with chalazion received a light-guided-tip IPL-MGX treatment (IPL-MGX group), and another 95 eyes with chalazion received incision with curettage treatment (Control group). Prior to IPL or incision, as well as 1 month after the final treatment, data were gathered pertaining to the lesion location and size, hyperemia, lesions regression or recurrence, and a comprehensive ophthalmic examination. The total size of the chalazia in the IPL-MGX group was significantly reduced after the final treatment, with an average resolution rate of 70.5%, which is comparable to excision surgery. A significant decrease in chalazion recurrence rate was apparent after treatment in the IPL-MGX group compared with control. Moreover, the IPL-MGX demonstrated significant advancements throughout noninvasive tear film breakup time (NIBUT) as well as meibum grade in comparison to baseline and those in the the Control group. The use of IPL-MGX was found to be an efficient therapy for reducing the size and recurring frequency of chalazia, as well as for improving the meibomian gland function. It may be considered as a first-line treatment for cases of primary or recurrent chalazia with inflammation.

Novel acoustic radiation force optical coherence elastography based on ultrasmall ultrasound transducer for biomechanics evaluation of in vivo cornea.

We developed a novel acoustic radiation force optical coherence elastography (ARF-OCE) based on an ultrasmall ultrasound transducer for quantitative biomechanics evaluations of in vivo cornea. A custom single-sided meta-ultrasonic transducer with an outer diameter of 1.8 mm, focal spot diameter of 1.6 mm, central frequency of 930 kHz, and focal length of 0.8 mm was applied to excite the sample. The sample arm of the ARF-OCE system employed a three-dimensional printed holder that allowed for ultrasound excitation and ARF-OCE detection. The phase-resolved algorithm was combined with a Lamb wave model to depth-resolved evaluate corneal biomechanics after keratoconus and cross-linking treatments (CXL). The results showed that, compare to the healthy cornea, the Lamb wave velocity was significantly reduced in the keratoconus, increased in the cornea after CXL, and increased with cross-linked irradiation energy in the cornea. These results indicated the good clinical translation potential of the proposed novel ARF-OCE.

COVID-19 and ocular complications: A review of ocular manifestations, diagnostic tools, and prevention strategies.

Background: The novel severe acute respiratory syndrome coronavins 2 (SARS-CoV-2) led to the severe Corona Virus Disease 2019 (COVID-19) outbreak that started in December 2019 in China and caused enormous health and economic problems worldwide. Over time, SARS-CoV-2 has demonstrated the capacity for mutation. As the most prevalent new coronavirus variety worldwide, the Omicron variant has supplanted the Delta variant. The COVID-19 primarily damages the immune system and the lungs, but it can also harm other organs secondarily, depending on the patients' co-existing conditions. Main Text: COVID-19 is associated with ophthalmic manifestations such as conjunctival congestion, tear overflow, and conjunctival edema, with the majority of eye complications occurring in patients with severe infection. The virus may make a patient more susceptible to thrombotic conditions that affect venous and arterial circulation. Meanwhile, it can lead to efferent complications and mucormycosis which is more common in patients with diabetes or who have critical or severe SARS-CoV-2 infection. Significantly, there are a number of ocular side effects following the COVID-19 vaccination, such as herpetic keratitis and facial nerve palsy, which have been reported. These side effects may be caused by the vaccinations' propensity to trigger autoimmune symptoms or thromboembolic events. At present, large-scale nucleic acid testing mainly relies on nasopharyngeal swabs and throat swabs. Tear samples and conjunctival swabs may be helpful samples for the diagnosis of ocular SARS-CoV-2 infection. The eye could be a new route of infection, and finding ways such as effective environmental disinfection, scientific administrative control management, qualified personal protection and other measures to protect the eyes could further reduce the risk of infection. Conclusions: This review aims to sum up the ocular complications of COVID-19, the possible pathogenesis, and preventive strategies to protect ophthalmology practitioners and patients by reviewing the currently available literature on the topic.

Long-Term Clinical Outcome of Low-Temperature Plasma Ablation Treatment for Recurrent Corneal Erosions.

Purpose: To observe the therapeutic effect of low-temperature plasma ablation in treating patients with recurrent corneal erosions (RCEs). Materials and Methods: From 2020 to 2022, 35 participants with unilateral RCEs voluntarily enrolled. Here, 35 eyes of 35 patients were treated with low-temperature plasma ablation (coblation). All surgeries were performed by the same doctor (X.H.). The coblation went back and forth over the entire erosion area around five times for about five minutes. After the operation, patients were scheduled for follow-up visits at the outpatient clinic after 1 month, 3 months, 6 months, and 12 months, and at the end of the trial. During every visit, each patient underwent an evaluation of their ocular symptoms utilizing the following: pain score, intraocular pressure, slit lamp biomicroscopic examination, dry eye analysis, corneal topography, and corneal in vivo confocal microscopy (IVCM). Results: The mean follow-up time was 12.4 ± 6.1 months, ranging from 6 to 29 months. Of the 35 patients who had low-temperature plasma ablation, 32 eyes (91.43%) were completely symptom-free and three (8.57%) eyes had repeated episodes of recurrent corneal erosions after the surgery, at 3, 10, and 12 months, respectively. The typical RCE morphologic abnormalities observed in IVCM included the deformation and relaxation of the corneal epithelium, disorganized stromal fibers, reduced nerve fiber density, and disordered organization. After low-temperature plasma ablation, the loose cysts disappeared, and the epithelium became solid and tight. There was no obvious difference in the intraocular pressure (p = 0.090) or corneal astigmatism (p = 0.175) before and after treatment. The mean pain score decreased significantly, with a preoperative score of 7.7 ± 2.4 and postoperative score of 1.1 ± 1.8 (p < 0.001). The mean corneal thickness decreased from 562.6 ± 42.2 mm to 549.6 ± 26.9 mm (p = 0.031). The mean non-invasive keratograph tear meniscus height (NIKTMH) decreased from 0.210 ± 0.054 mm to 0.208 ± 0.045 mm (p = 0.001), and the mean TBUT decreased from 6.191 ± 2.811 s to 5.815 ± 2.802 s (p < 0.001), which manifested as a slight worsening of dry eyes. In one case, the patient's corneal astigmatism became more severe, which may be related to the high instantaneous energy when the operation did not flush in a timely manner, and it was recovered after 6 months. Conclusions: Low-temperature plasma ablation is an effective and safe procedure to treat patients with recurrent corneal erosions.

Quantitative Assessment of Biomechanical Properties of the Human Keratoconus Cornea Using Acoustic Radiation Force Optical Coherence Elastography.

Purpose: Quantification of biomechanical properties of keratoconus (KC) corneas has great significance for early diagnosis and treatment of KC, but the corresponding clinical measurement remains challenging. Here, we developed an acoustic radiation force (ARF) optical coherence elastography technique and explored its potential for evaluating biomechanical properties of KC corneas. Methods: An ARF system was used to induce the tissue deformation, which was detected by an optical coherence tomography system, and thus the localized point-by-point Young's modulus measurements were achieved. Then, two healthy rabbit eyes were imaged to test the system, after which the human keratoconus cornea was evaluated by using the same method. Three regions were selected for biomechanics analysis: the conical region, the transitional region, and the peripheral region. Results: Young's moduli of transitional region ranged from 53.3 to 58.5 kPa. The corresponding values for the peripheral region were determined to be 58.6 kPa and 63.2 kPa, respectively. Young's moduli of the conical region were gradually increased by 18.3% from the center to the periphery, resulting in the minimum and maximum values of 44.9 kPa and 53.1 kPa, respectively. Furthermore, Young's moduli of the anterior and posterior of the center were determined to be 44.9 kPa and 50.7 kPa, respectively. Conclusions: Differences in biomechanical properties between the three regions and slight variations within the conical region were clearly distinguished. Biomechanical weakening of the keratoconus cornea was mainly localized in the conical region, especially in the vertex position. Translational Relevance: The system may provide a promising clinical tool for the noninvasive evaluation of local corneal biomechanics and thus may have potential applications in early keratoconus detection with further optimization.

Efficacy of Intense Pulsed Light Combined Blood Extract Eye Drops for Treatment of Nociceptive Pain in Dry Eye Patients.

PURPOSE: To investigate the efficacy of intense pulsed light (IPL) combined with deproteinized calf blood extract (DCBE) eye drops for dry eye disease (DED) patients with nociceptive ocular pain. METHODS: In this prospective, one-center, interventional study, 23 subjects with DED and ocular pain were treated with a combination of IPL and DCBE eye drops for four sessions at a four-week interval. Subjective and objective assessments on nociceptive pain and dry eye were examined and analyzed. RESULTS: The visual analog scale (VAS), ocular surface disease index, ocular pain assessment survey (OPAS), patient health questionnaire-9 items, generalized anxiety disorder (GAD-7), Athens insomnia scale, corneal fluorescein staining score, meibomian gland secretion quality, and expressibility scores were significantly reduced after the treatment. Tear break-up time and Schirmer I test increased significantly. The brand density of corneal nerves and neuropeptide substance P also significantly increased. OPAS, GAD-7, meibomian gland secretion quality, and expressibility scores were essential factors affecting the VAS changes. CONCLUSIONS: IPL combined with DCBE drop therapy was effective for DED patients with ocular pain. With such treatment, both DED symptoms and the sensation of ocular pain may be improved.

Sleep Quality Is Associated With Severe Meibomian Gland Disruption in Dry Eye.

PURPOSE: To investigate the association between sleep quality and meibomian gland dropout characteristics in dry eye patients. METHODS: This cross-sectional study involved 172 dry eye patients with no history of conditions or factors that could confound dry eye disease (DED) and/or meibomian gland dropout. Participants underwent a comprehensive anterior eye assessment. The validated Athens Insomnia Scale (AIS) and Pittsburgh Sleep Quality Index (PSQI) were used to assess sleep quality. The measured outcomes were dry eye symptoms via the Ocular Surface Disease Index (OSDI), tear breakup time (TBUT), corneal fluorescein staining, meibomian gland function, and extent of meibomian gland dropout. RESULTS: Of the dry eye participants, 34.9% had severe meibomian gland dropout (SMD) and 41.3% of the subjects had poor sleep quality. Patients with poor sleep quality had greater Meibomian gland dropout while the sleep AIS and PSQI scores were significantly correlated with Meibomian gland dropout (r = 0.495, p < 0.001; r = 0.24, p = 0.002; respectively). SMD patients had worse scores on all components of the PSQI (all p < 0.001, corrected for age and sex). Use of sleep medication, poor habitual sleep efficiency, and sleep disturbance were particularly prevalent in SMD patients as compared to Non-severe meibomian gland dropout (NSMD) patients. Multivariate logistic regression analysis revealed that sleep quality was eventually associated with female gender (p = 0.042), OSDI (p = 0.004), TBUT (p = 0.036), and Meibomian gland dropout score (p < 0.001). CONCLUSION: It was found that greater meibomian gland dropout in poor sleep quality individuals is especially related to use of sleep medication, poor habitual sleep efficiency, and sleep disturbance. This finding suggests a need for long-term studies of anterior eye health in people with poor sleep quality.

Efficacy of Intense Pulsed Light in the Treatment of Recurrent Chalaziosis.

Purpose: High recurrence rate of chalaziosis and serious side effects of repeated surgical excision may help increase awareness of recurrent and refractory chalaziosis as a serious disorder affecting many aspects of life. This present study was aimed to investigate the efficacy and safety of intense pulse light (IPL) therapy and meibomian gland expression (MGX) in cases of recurrent chalaziosis after excision surgery. Methods: Forty-two consecutive recurrent chalaziosis cases (35 patients) treated with IPL-MGX were enrolled. All patients initially underwent excision with curettage. One week after lesion excision, IPL-MGX were performed at least 3 times. Another set of age- and sex-matched consecutive cases of recurrent chalaziosis, who received excision with curettage, but went without IPL-MGX treatment, were collected to calculate recurrence rate. Treatment efficacy and safety were measured before IPL-MGX treatment and 1 month after the final treatment. Results: The majority of patients received 4 sessions of IPL-MGX therapy (20 patients; 57.1%) or 3 sessions of IPL-MGX therapy (10 patients; 28.6%), resulting in a lower recurrence rate of 11.4% compared to that of recurrent chalaziosis without IPL-MGX cases (45.6%, P < 0.001). The NIBUT was significantly prolonged from 3.9 ± 1.8 to 5.1 ± 1.7 s at 4 weeks after the final treatment (P = 0.001). Similarly, mean TMH score improved and was statistically significant when compared with baseline (0.17 ± 0.07 vs. 0.21± 0.09; P = 0.008). Furthermore, meibum quality and expressibility scores significantly improved at 4 weeks following the final treatment (both P < 0.001). Other variables, such as intraocular pressure and visual acuity, remained unaffected following treatment. Conclusion: The combination of IPL treatment and MGX offers a low risk and effective option in decreasing the recurrence rate of recurrent chalaziosis by improving meibomian gland function. IPL-MGX may be considered for first-line treatment in recurrent or refractory cases post excision.

In Vivo Evaluation of the Effects of SMILE with Different Amounts of Stromal Ablation on Corneal Biomechanics by Optical Coherence Elastography.

This work aims to depth-resolved quantitatively analyze the effect of different stromal ablation amounts on the corneal biomechanical properties during small incision lenticule extraction (SMILE) using optical coherence elastography (OCE). A 4.5-MHz ultrasonic transducer was used to excite elastic waves in the corneal tissue. The OCE system combined with the antisymmetric Lamb wave model was employed to achieve a high-resolution, high-sensitivity, and depth-resolved quantitative detection of the corneal Young's modulus. Eighteen rabbits were randomly divided into three groups; each group had six rabbits. The first and second groups underwent -3D and -6D SMILE surgeries, and the third group was the control group, respectively. Young's modulus of the corneal cap and residual stromal bed (RSB) were both increased after SMILE, which shared the stress under intraocular pressure (IOP). Furthermore, the Young's modulus of both the corneal cap and RSB after 3D SMILE group were significantly lower than that in the -6D group, which indicated that the increases in the post-operative corneal Young's modulus were positively correlated with the amount of stromal ablation. The OCE system for quantitative spatial characterization of corneal biomechanical properties can provide useful information on the extent of safe ablation for SMILE procedures.

Quantification of biomechanical properties of human corneal scar using acoustic radiation force optical coherence elastography.

Biomechanical properties of corneal scar are strongly correlated with many corneal diseases and some types of corneal surgery, however, there is no elasticity information available about corneal scar to date. Here, we proposed an acoustic radiation force optical coherence elastography system to evaluate corneal scar elasticity. Elasticity quantification was first conducted on ex vivo rabbit corneas, and the results validate the efficacy of our system. Then, experiments were performed on an ex vivo human scarred cornea, where the structural features, the elastic wave propagations, and the corresponding Young's modulus of both the scarred region and the normal region were achieved and based on this, 2D spatial distribution of Young's modulus of the scarred cornea was depicted. Up to our knowledge, we realized the first elasticity quantification of corneal scar, which may provide a potent tool to promote clinical research on the disorders and surgery of the cornea.

Quantitative Evaluation of In Vivo Corneal Biomechanical Properties after SMILE and FLEx Surgery by Acoustic Radiation Force Optical Coherence Elastography.

The purpose of this study is to quantitatively evaluate the differences in corneal biomechanics after SMILE and FLEx surgery using an acoustic radiation force optical coherence elastography system (ARF-OCE) and to analyze the effect of the corneal cap on the integrity of corneal biomechanical properties. A custom ring array ultrasound transducer is used to excite corneal tissue to produce Lamb waves. Depth-resolved elastic modulus images of the in vivo cornea after refractive surgery were obtained based on the phase velocity of the Lamb wave. After refractive surgery, the average elastic modulus of the corneal flap decreased (71.7 ± 24.6 kPa), while the elastic modulus of the corneal cap increased (219.5 ± 54.9 kPa). The average elastic modulus of residual stromal bed (RSB) was increased after surgery, and the value after FLEx (305.8 ± 48.5 kPa) was significantly higher than that of SMILE (221.3 ± 43.2 kPa). Compared with FLEx, SMILE preserved most of the anterior stroma with less change in corneal biomechanics, which indicated that SMILE has an advantage in preserving the integrity of the corneal biomechanical properties. Therefore, the biomechanical properties of the cornea obtained by the ARF-OCE system may be one of the essential indicators for evaluating the safety of refractive surgery.

Corneal Collagen Cross-Linking Pretreatment Mitigates Injury-Induced Inflammation, Hemangiogenesis and Lymphangiogenesis In Vivo.

Purpose: The purpose of this study was to evaluate if corneal collagen cross-linking (CXL) pretreatment dampens suture-induced hemangiogenesis and lymphangiogenesis driven by inflammation. Methods: Four weeks after CXL pretreatment, suture emplacement was performed in rats. The time dependent effects were compared of this procedure in three groups: (1) suture-induced neovascularization (SNV group); (2) CXL treatment prior to suture-induced neovascularization (CXL + SNV group); (3) Normal control (NC group). Serial morphometric measurements evaluated suture-induced hemangiogenesis and lymphangiogenesis. CD45 and CD68 immunofluorescent staining pattern changes determined immune cell activation, stromal leucocyte, and macrophage infiltration. The real-time quantitative polymerase chain reaction (RT-qPCR) determined angiogenic and lymphangiogenic gene expression level changes. Western blots evaluated protein expression levels of vascular endothelial cell CD31 and lymphatic vessel endothelial hyaluronan receptor (LYVE-1). Results: On days 7 and 14 after suture emplacement, the rises in angiogenesis, lymphangiogenesis, CD45+ and CD68+ cell infiltration were less in the CXL pretreated (CXL + SNV) group than in the untreated (SNV) group. Angiogenic and lymphangiogenic mRNA levels and CD31 and LYVE-1 protein and proinflammatory cytokines were also suppressed, confirming that CXL pretreatment improved the wound healing response. Conclusions: CXL pretreatment inhibits injury-induced angiogenesis and lymphangiogenesis. These reductions suggest that prior CXL therapy decrease ocular inflammation reactivated by secondary trauma. Translational Relevance: CXL pretreatment induces increases in stromal stiffness which in turn reduces trauma or microbial driven increases in inflammation, angiogenesis, and lymphangiogenesis. These beneficial effects suggest that this novel procedure may improve therapeutic management of trauma-induced corneal disease in a clinical setting.

1.7-Micron Optical Coherence Tomography Angiography for Characterization of Skin Lesions-A Feasibility Study.

Optical coherence tomography (OCT) is a non-invasive diagnostic method that offers real-time visualization of the layered architecture of the skin in vivo. The 1.7-micron OCT system has been applied in cardiology, gynecology and dermatology, demonstrating an improved penetration depth in contrast to conventional 1.3-micron OCT. To further extend the capability, we developed a 1.7-micron OCT/OCT angiography (OCTA) system that allows for visualization of both morphology and microvasculature in the deeper layers of the skin. Using this imaging system, we imaged human skin with different benign lesions and described the corresponding features of both structure and vasculature. The significantly improved imaging depth and additional functional information suggest that the 1.7-micron OCTA system has great potential to advance both dermatological clinical and research settings for characterization of benign and cancerous skin lesions.

Quantification of iris elasticity using acoustic radiation force optical coherence elastography.

Careful quantification of the changes in biomechanical properties of the iris can offer insight into the pathophysiology of some ocular diseases. However, to date there has not been much information available regarding this subject because clinical detection for iris elasticity remains challenging. To overcome this limitation, we explore, for the first time to our knowledge, the potential of measuring iris elasticity using acoustic radiation force optical coherence elastography (ARF-OCE). The resulting images and shear wave propagation, as well as the corresponding shear modulus and Young's modulus from ex vivo and in vivo rabbit models confirmed the feasibility of this method. With features of noninvasive imaging, micrometer-scale resolution, high acquisition speed and real-time processing, ARF-OCE is a promising method for reconstruction of iris elasticity and may have great potential to be applied in clinical ophthalmology with further refinement.

Corneal Collagen Cross-Linking With Riboflavin and UVA Regulates Hemangiogenesis and Lymphangiogenesis in Rats.

Purpose: The purpose of this study was to determine whether corneal collagen crosslinking (CXL) inhibits hemangiogenesis and lymphangiogenesis during acute corneal inflammation in an in vivo rat model. Methods: Inflammatory corneal neovascularization was induced by suture placement into a rat cornea. At day 3 after suture, a CXL protocol using riboflavin and UVA was administered after mechanical epithelial debridement. Hemangiogenesis and lymphangiogenesis were analyzed morphometrically. CD45 and CD68 immunostaining evaluated corneal leucocyte and macrophage immune cell infiltration, respectively. A TUNEL assay detected stromal cell apoptosis. Quantitative RT-PCR analysis identified angiogenic and lymphangiogenic genes as well as proinflammatory cytokine expression. Western blot analysis characterized vascular endothelial cell CD31 and lymphatic vessel endothelial hyaluronan receptor (LYVE-1) protein expression. Results: CXL treatment significantly reduced corneal pathologic suture-induced hemangiogenesis and lymphangiogenesis 7 days after suture emplacement, but this procedure failed to affect hemangiogenesis and lymphangiogenesis 14 days after suture. Increased cell apoptosis and reduced CD45+ and CD68+ cell infiltration were evident in CXL-treated rats on days 7 and 14 after suture emplacement. CXL treatment significantly decreased angiogenic and lymphangiogenic mRNA expression levels and both CD31 and LYVE-1 protein expression levels, whereas it increased proinflammatory cytokine levels on day 7 after suture emplacement. However, on day 14 after corneal neovascularization, angiogenic and lymphangiogenic mRNA gene expression levels were upregulated along with hematic CD31 and lymphatic LYVE-1 protein expression. Conclusions: CXL treatment only temporarily inhibits corneal inflammatory-associated hemangiogenesis and lymphangiogenesis in vivo. Such insight suggests that future studies are warranted to develop novel CXL strategies with longer-lasting effectiveness in attenuating hemantic- and lymphatic-related corneal diseases.

Continuous-light versus pulsed-light accelerated corneal crosslinking with ultraviolet-A and riboflavin.

PURPOSE: To determine whether the pulsed-light ultraviolet-A (UVA) accelerated corneal crosslinking (CXL) procedure is more efficacious and selective than its continuous-light counterpart in rabbits. SETTING: School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China. DESIGN: Experimental study. METHODS: Fifty-four rabbits were divided into 2 groups. Group 1 had continuous-light accelerated CXL using 9 mW/cm2 UVA for 10 minutes (5.4 J/cm2). Group 2 had pulsed-light accelerated CXL by exposing them to 9 mW/cm2 UVA for 20 minutes (1 second on/1 second off). Corneal stromal demarcation line depth, in vivo confocal microscopic analysis, biomechanical stiffness, endothelial cell density, and keratocyte apoptosis were measured after performing these CXL procedures. RESULTS: The mean stromal demarcation line depth was 254.7 µm ± 47.4 (SD) in Group 1 and 341.1 ± 36.1 µm in Group 2 (P < .01). One day after CXL, confocal analysis and histological staining identified keratocyte apoptotic fragments in the anterior stroma in the Group 2 corneas whereas all cells were obliterated in Group1. Seven days after treatment, the thicknesses in Group 1 were significantly greater than those in Group 2 (P < .05). Endothelial cell losses were reversible; however, in Group 1, some losses were still evident on day 7. Increases in both the stress-strain relationship and tangent modulus in Group 2 were greater than those in Group 1. CONCLUSION: The pulsed-light accelerated CXL protocol was less injurious and more efficacious at inducing CXL than the continuous-light accelerated CXL protocol in rabbit corneas.