Detection of a novel PAX6 variant in a Chinese family with multiple ocular abnormalities

Background Aniridia is a congenital, panocular disease that can affect the cornea, anterior chamber angle, iris, lens, retina and optic nerve. PAX6 loss-of-function variants are the most common cause of aniridia, and variants throughout the gene have been linked to a range of ophthalmic abnormalities. Furthermore, particular variants at a given site in PAX6 lead to distinct phenotypes. This study aimed to characterize genetic variants associated with congenital aniridia in a Chinese family. Methods The proband and family underwent ophthalmologic examinations. DNA was sampled from the peripheral blood of all 6 individuals, and whole-exome sequencing was performed. Sanger sequencing was used to verify the variant in this family members. Results A novel variant (c.114_119delinsAATTTCC: p.Pro39llefsTer17) in the PAX6 gene was identified in subjects II-1, III-1 and III-2, who exhibited complete aniridia and cataracts. The proband and the proband’s brother also had glaucoma, high myopia, and foveal hypoplasia. Conclusions We identified that a novel PAX6 frameshift heterozygous deletion variant is the predominant cause of aniridia in this Chinese family. Trial registration We did not perform any health-related interventions for the participants.

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.

Vitreous function and intervention of it with vitrectomy and other modalities

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy may lead to postoperative nuclear cataract and a high incidence of open angle glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous, and encourages conducting vitreous interventions prudently.

Malignant Glaucoma in a Pseudophakic Eye with Slack Lens Zonules

Purpose: To report a case of malignant glaucoma after glaucoma surgery in a pseudophakic eye with slack lens zonules.Case summary: An 83-year-old man presented with high intraocular pressure of the left eye. He underwent cataract surgery in the left eye ten years ago. He was diagnosed with glaucoma two years ago and had used anti-glaucoma medications. The initial examination of the left eye revealed intraocular pressure of 24 mmHg and zonular dehiscence. We performed Ahmed valve implant surgery because medical treatment failed to lower the intraocular pressure. The anterior chamber angle was nearly closed. After the surgery, over-filtration of aqueous fluid was observed. Injecting the balanced salt solution into the anterior chamber demonstrated misdirected flow of aqueous fluid into the vitreous cavity behind the unstable intraocular lens. The eye was diagnosed with malignant glaucoma; therefore, pars plana vitrectomy was performed. After the vitrectomy, the anterior chamber was not deep; therefore, we repositioned the tip of Ahmed valve implant from the anterior chamber to the vitreous cavity. Subsequently, the anterior chamber became deep and intraocular pressure normalized. The patient remained stable two months after the vitrectomy.Conclusions: Malignant glaucoma can occur in pseudophakic eyes with slack lens zonules after glaucoma surgery, due to misdirection of aqueous fluid. This case suggests that the tip of Ahmed valve implant should be located in the vitreous cavity after vitrectomy, to prevent misdirected flow of aqueous fluid.

Viscoelastic properties of the iris in different types of glaucoma

Introduction. The iris is involved in maintaining the ocular hydrodynamic homeostasis as one of the elements of the anterior chamber angle of the eye. From there, the iris is one of the parts of its drainage area. The anterior chamber angle’s structure can predispose to an increase in intraocular pressure and thereby provoke the development of primary angle-closure glaucoma, a disease accompanied by clogging of the drainage area of the eye and, accordingly, an increase in intraocular pressure.Objective. To analyse the viscoelastic properties of the iris in primary angle-closure glaucoma and primary open-angle glaucoma.Materials and methods. The study material was a fragment of the iris obtained through iridectomy in the course of sinus trabeculectomy, which is considered the treatment for glaucoma surgery. A total of 43 samples (43 patients) were obtained and analysed, with 20 samples obtained from patients with primary angle-closure glaucoma (group 1), and 23 samples from patients with primary open-angle glaucoma (group 2). A standard ophthalmological examination, which included visometry, autorefractometry, tonometry, biomicroscopy, and indirect ophthalmoscopy, was carried out. The special examination included static perimetry, gonioscopy, ultrasound biomicroscopy or optical coherence tomography of the anterior chamber angle, optical coherence tomography of the disk of optic nerve.Results and discussion. The avascular part of the stroma (designated by us as S) is the most rigid part of the iris, according to the study. It is characterized by the greatest efforts of the viscous dynamic resistance to the indenter (0.4–2.0 gf/мм2 × S), as well as the maximum integral tensile strength (up to 4.9 × 10-2 N). The inner (vascular) part of the stroma has the lowest dynamic viscosity, according to this study.Conclusion. The samples vary enormously both in the biomechanical characteristics and relative thickness of this layer. It was observed that this biomechanically incompetent structure completely collapses and ceases to exist in partial dehydration of the sample.

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.