Congenital Disorders

This chapter is devoted to specific diseases presenting usually in early infancy or childhood as a result of disruption in the normal development of the cornea and its associated structures. These disorders may develop due to one or a combination of various genetic, infectious, inflammatory, toxic, metabolic, traumatic, or mechanical processes and may occur at any time during tissue induction, differentiation, and maturation. Adjacent structures (anterior chamber angle, iris, and lens) can be impacted too. Congenital limbal stem cell deficiency is usually associated with aniridia and ectodermal dysplasia. Aniridia can occur in a sporadic or familial form. The familial inheritance pattern of aniridia is predominantly autosomal dominant. The aniridia phenotype varies depending on the mutation present. Interesting ocular congenital disorders associated with Neurofibromatosis, Axenfeld-Rieger syndrome, Icthyosis are shown in this chapter. It presents a rare case of porphyria-associated sclerocorneal melting with before and after treatment photos.

Moving beyond the Slit-Lamp Gonioscopy: Challenges and Future Opportunities

After almost a century from its introduction in clinical practice, slit-lamp gonioscopy is still considered the reference standard for evaluating the anterior chamber angle (ACA). Gonioscopy is essential for diagnosing angle closure disease, and ACA features are included in glaucoma’s diagnostics and treatments algorithms. However, shortcomings of slit-lamp gonioscopy include a steep learning curve, lack of agreement between examiners and poor documentation. Thanks to advances in miniaturization and computing, new instruments for digital gonioscopy have been developed and marketed. This narrative review focuses on the Gonioscope GS-1, which permits semi-automated circumferential documentation of the ACA in real-colour photographs. Advantages and disadvantages of GS-1 compared with slit-lamp gonioscopy and other ACA imaging technologies such as optical coherence tomography are discussed. Finally, potential opportunities offered by this device for telemedicine, virtual clinics, and automatic classification with deep learning are presented.

Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT

AIM: To assess the changes of anterior chamber angle in patients with shallow anterior chamber after phacoemulsification combined with intraocular lens (IOL) implantation, based on anterior segment swept-source optical coherence tomography (AS-SS-OCT) measurements. METHODS: This was a prospective case control study; sixty eyes of sixty case were scheduled for cataract surgery with normal intraocular pressure (IOP). Based on anterior chamber depth (ACD) and gonioscopy findings, the eyes were divided into two groups: group of shallow anterior chamber and narrow angle (SAC group, 30 eyes); and group of normal anterior chamber group with wide angle (NAC group, 30 eyes). Measurements of ACD, anterior chamber volume (ACV), iris volume (IV), lens vault (LV), angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), and trabecular iris angle (TIA) were conducted in each group before and 3mo after surgery. RESULTS: There was no significant difference in age, axial length (AL), corneal curvature, corneal diameter, intraocular pressure, and IV between two groups before surgery, except for the LV (P=0.000). ACD and ACV were prominently larger in the NAC group than the SAC group 3mo after operation (3.69±0.38 vs 3.85±0.39 mm, P=0.025; 161.37±19.47 vs 178.26±20.30 mm3, P=0.002). AOD750, ARA750 in nasal and inferior quadrants, TISA750 in all quadrants except temporal, and TIA750 in all quadrants in SAC group were significantly smaller than those in NAC group after operation (all P<0.05). CONCLUSION: Cataract surgery can deepen anterior chamber and increase the width of anterior chamber angle in Chinese subjects, but the angle related parameters including AOD750, ARA750, TISA750, TIA, TISA750, and ACV in patients with shallow anterior chamber and narrow angle do not reach the normal level.

Hydraulically Coupled Dielectric Elastomer Actuators for a Bioinspired Suction Cup

Suction cups of cephalopods show a preeminent performance when absorbing irregular or flat objects. In this paper, an octopi-inspired suction cup, driven by hydraulically coupled dielectric elastomer actuators (HCDEAs), is proposed, which is considered to be controlled easily and have compact structure. To investigate the performance of suction cups, experiments have been conducted to clarify the effect of the pre-stretch ratio and chamber angle on suction forces. It could be seen that both factors have a complicated influence on suction forces, and the best performance obtained was a reasonable combination of the pre-stretch ratio and chamber angle. Here, we achieved a maximum suction force of 175 mN with λp = 1.2, α = 23° under a DC voltage of 3500 V. To enhance the capacity and adaptation of the suction cup, flat objects of various types of materials were introduced as targets. Experimental results displayed that for tested materials, including a dry/wet acrylic plate, CD, ceramic wafer, and aluminum plate, the suction cup showed outstanding performance of absorbing and lifting the target without any damage or scratch to them. Our research may serve as a guide to the optimal design and provide insights into the performance of the HCDEAs-actuated suction cup.

Transient Angle Obstruction Detected by Anterior-Segment Optical Coherence Tomography and Intraocular Pressure Elevation after Hemodialysis

An 80-year-old Japanese man presented with decreased vision in his right eye (OD) after every hemodialysis (HD) session beginning several months previously. His local ophthalmologist prescribed antiglaucoma medications because of high intraocular pressure (IOP) (38 mm Hg) OD 4 months previously; with treatment, the IOP fluctuated between 6 and 34 mm Hg OD. When hospitalized, the IOP was measured, and the anterior chamber was observed by anterior-segment optical coherence tomography (AS-OCT) before and after HD. Before HD, the IOP levels were 7 mm Hg OD and 8 mm Hg in the left eye (OS). AS-OCT showed marked anterior iris bowing due to circumferential posterior synechia OD. The scan showed irido-trabecular contact (ITC) in the nasal angle and not the temporal angle OD. Immediately after HD, the IOP levels were 28 mm Hg OD and 12 mm Hg OS; AS-OCT showed ITC in the nasal and temporal angles OD. Since the iris bombe and HD-induced increase in the ITC were expected to have caused the IOP spike and blurred vision, posterior synechialysis and goniosynechialysis were performed OD. Postoperatively, the iris plane flattened; no IOP spike was recorded, and the blurred vision after HD resolved. At 22 months postoperatively, the IOP was 7 mm Hg in both eyes (OU). No deterioration of visual acuity and visual field was recorded during the follow-up period OU. IOP spikes can occur during and after HD because of transient anterior chamber angle obstruction in cases with narrow angles. AS-OCT is useful for detecting minor morphologic changes in the anterior chamber angle during HD.

Aflibercept clearance through the drainage system in a rat model

Background As intravitreal anti-VEGF injections became the mainstay of treatment for many retinal diseases, the cause of a secondary sustained elevated intraocular pressure is still unclear. The aim of our study was to study the clearance of Aflibercept from the anterior chamber angle, in a rat model, to test if an aggregation exists. Methods Choroidal neovascular lesions (CNV) were induced in the right eye of 12 brown Norway rats, using indirect laser ophthalmoscope. Intravitreal Aflibercept injection (0.12 mg/3 µl) was performed 3 days after CNV induction. Rats were euthanized at predetermine time intervals of 3, 6, 24 and 48 h post injection, with immediate enucleation for histological analysis with H&E and immunofluorescence staining. Aflibercept molecules were stained with red fluorescence thanks to the formation of the immune complex Aflibercept-Rabbit anti human IgG-Anti rabbit antibodies-Cy3. Results Immediately after the injection, a strong fluorescence signal was detected, indicating the presence of Aflibercept in the iridocorneal angle. At 3- and 6-h interval a strong signal of Aflibercept was still seen. Six hours post injection, the signal was highly concentrated in Schlemm’s canal. In the 2 eyes harvested 24 h post Aflibercept injection, red fluorescence signal intensity was decreased in one eye, occupying mainly intra scleral venous plexuses, and absent in the other eye. At 48 h there was no fluorescence signal, confirming complete clearance of Aflibercept. Conclusions In our rat model, a complete clearance of Aflibercept from the anterior chamber angle, was seen 48 h after the injection. This finding refutes the theory of possible connection between IOP elevation and mechanical obstruction. Evacuation time of Aflibercept through the angle is of the same magnitude as that of Bevacizumab in the same rat model.

Analysis of Primary Iris and Ciliary Body Cysts in Chinese Patients With Primary Angle Closure Disease

Aim: To investigate the incidence and clinical features of primary iris and ciliary body cysts in Chinese primary angle closure disease (PACD). Patients were evaluated by measuring and analyzing the cysts with an ultrasound biomicroscope (UBM).Methods: The data of patients diagnosed with PACD were reviewed. Demographic data were collected, and the cyst number, size, location, and trabecular-iris angle (TIA) were measured, with the size including the longest diameter (LD) and its corresponding vertical diameter (CVD).Results: A total of 1,334 cases (2,317 eyes) were reviewed, and 409 cysts were found in 131 cases (168 eyes), with an average of 2.43 ± 3.14 cysts per eye. The ages of the patients with cysts ranged from 25 to 80 years, with an average age of 55.24 ± 12.22 years. The detection rate was 7.3%, and the majority of cysts were located in the iridociliary sulcus. Among the 131 patients, 94 had monocular cysts, while binocular cysts occurred in 37 patients. The locations of the cysts in both eyes were mainly in the inferior and temporal quadrants (42.5 and 34.0%, respectively). The cysts were mainly of medium size (49.9%), followed by small cysts (33.3%), large cysts (14.7%) and giant cysts (2.2%). The average LD was 0.68 ± 0.33 mm, and the average CVD was 0.45 ± 0.23 mm. There were no statistically significant differences in the TIA between the cyst area and unaffected area.Conclusions: The incidence of cysts is 7.3% in the PACD population. The cysts are mainly monocular, medium in size, and located in the iridociliary sulcus. Additionally, the cysts were located mainly in the inferior and temporal quadrants. These cysts have little effect on the anterior chamber angle.