Intraocular Pressure Monitoring Following Islet Transplantation to the Anterior Chamber of the Eye.

Intraocular islet transplantation was investigated as a new procedure to treat diabetes. The development of this procedure requires close monitoring of the function of both eye and islet graft. We developed a soft, smart contact lens to monitor the intraocular pressure and applied this for noninvasive monitoring in association with the intraocular islet transplantation in diabetes. A strain sensor inside the lens can detect detailed changes in intraocular pressure by focusing the strain only in the desired, selective area of the contact lens. In addition, this smart contact lens can transmit the real-time value of the intraocular pressure wirelessly using an antenna. The wireless measurement of intraocular pressure that was obtained using this contact lens had a high correlation with the intraocular pressure measured by a rebound tonometer, thereby proving the good accuracy of the contact lens sensor. In the initial period, a slight elevation of intraocular pressure was observed, but the pressure returned to normal in the initial period after the transplantation. This type of monitoring will provide important information on potential changes in the intraocular pressure associated with the transplantation procedure, and it enables appropriate clinical safety steps to be taken, if needed.

Evaluation of the effects of selective laser trabeculoplasty on anterior segment parameters by anterior segment optical coherence tomography.

To prospectively examine the effects of selective laser trabeculoplasty (SLT) on the anterior chamber angle (ACA) and its related parameters using anterior segment-optic coherence tomography (AS-OCT). Fifty eyes of 50 patients with primary open angle glaucoma (POAG) and ocular hypertension were included in the study. AS-OCT was performed before SLT application, immediately after and at 1 day and 1 month. Intraocular pressure (IOP), central corneal thickness (CCT) and anterior chamber depth (ACD) were also recorded and evaluated. No statistically significant difference was determined in ACA and other AS-OCT parameters (AOD, angle opening distance at 500 and 750 mm; TISA, trabecular-iris space area at 500 and 750 mm) before and 1 day after SLT application (p > 0.05). However, a statistically significant increase was determined in both the temporal and nasal ACA, AOD and TISA values between the baseline and day 30 (p < 0.001). No statistically significant change was observed in the CCT or ACD values (p > 0.05). SLT resulted in an increase in ACA, AOD and TISA when evaluated using AS-OCT. We think that this study provides a different perspective concerning the effects of SLT in the angle region and the involved mechanism.

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications.

PURPOSE: Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. METHODS: The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). RESULTS: A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). CONCLUSION: The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.

Ocular biometric changes with different accommodative stimuli using swept-source optical coherence tomography.

PURPOSE: To evaluate ocular biometric changes with different accommodative stimuli using a new swept-source optical biometer. METHODS: Only the right eye was analyzed. Each subject was measured six times with the IOLMaster 700 swept-source optical biometer (Carl Zeiss Meditec, Jena, Germany) with the subject looking at the stimulus shown by the instrument and with the subject looking at a target placed outside the instrument at 0D of vergence. Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT), white-to-white (WTW), and keratometry readings (K1 and K2) were evaluated in both cases. To assess if the changes found may affect the intraocular (IOL) power calculation for surgical applications, we have applied some formulae, using the software provided by the optical biometer manufacturer, to the ocular parameters found in both situations for three different types of IOLs. RESULTS: No statistically significant differences were found for AL, CCT, WTW, K1 and K2 between the subject looking at the stimulus of the biometer and looking at the outside target at 0D of vergence (p > 0.05). However, the measurement of ACD revealed a statistically significant reduction of 20 microns (p = 0.03) and, on the contrary, LT increased significantly 30 microns (p = 0.02). ACD and LT changes were highly correlated (R2 = 0.91). As for the IOL power calculation, in all cases, the mean change was lower than 0.25 D both for IOL power selection and residual refraction. CONCLUSIONS: Although ACD and LT change significantly with different accommodative stimuli measured by swept-source optical biometry, these changes are not clinically relevant.

Dexamethasone Intracameral Drug-Delivery Suspension for Inflammation Associated with Cataract Surgery: A Randomized, Placebo-Controlled, Phase III Trial.

PURPOSE: To evaluate the safety and efficacy of an anterior chamber intracameral dexamethasone drug-delivery suspension (IBI-10090; DEXYCU; Icon Bioscience Inc., Newark, CA) that provides medication for up to 21 days with a single application in treating postoperative inflammation in patients undergoing cataract surgery. DESIGN: Prospective, randomized, double-masked, multicenter trial. PARTICIPANTS: Patients with preoperative best-corrected visual acuity of 20/30 to 20/200 undergoing unilateral cataract surgery by phacoemulsification were randomized to receive IBI-10090 or placebo. METHODS: Three hundred ninety-four patients were randomized 1:2:2 to receive 5-µl injections of placebo or 5-µl injections of 342 or 517 µg IBI-10090 dexamethasone drug delivery suspension injected into the anterior chamber at the conclusion of cataract surgery. Patients were followed for 90 days after surgery. MAIN OUTCOME MEASURES: Primary outcome was anterior chamber cell (ACC) clearing (ACC score of 0) in the study eye at postoperative day (POD) 8. Secondary outcome measures were anterior chamber flare and ACC plus flare clearing in the study eye. Ocular and nonocular adverse events were assessed. RESULTS: Anterior chamber cell clearing at POD 8 was achieved in 25.0% of eyes in the placebo group and in 63.1% and 66.0% of eyes in the 342- and 517-µg treatment groups, respectively (P < 0.001). Anterior chamber flare clearing at POD 8 was achieved by 63.8% of eyes in the placebo group and in 92.4% and 89.1% of eyes in the 342- and 517-µg IBI-10090 treatment groups, respectively (P < 0.001). Anterior chamber cell plus flare clearing at POD 8 was achieved in 33.8% of eyes receiving placebo and in 63.1% and 67.3% of eyes receiving 342- and 517-µg IBI-10090, respectively (P < 0.001). Adverse events among the 3 groups were similar, and no serious ocular adverse events were reported up to POD 90. CONCLUSIONS: The IBI-10090 dexamethasone drug-delivery suspension placed in the anterior chamber after cataract surgery at concentrations of 342 and 517 µg was safe and effective in treating inflammation occurring after cataract surgery and may be an alternative to corticosteroid drop installation in this patient population.

Acute and chronic fluid misdirection syndrome: pathophysiology and treatment.

PURPOSE: To summarize our current understanding of the specific pathogenic mechanisms of the fluid misdirection syndrome and possible treatment methods. METHODS: We used the PubMed web platform to find relevant studies using the following keywords: infusion misdirection syndrome, aqueous misdirection syndrome, ciliary block, ciliovitreal block, capsular block, intraoperative fluid misdirection, subcapsular fluid entrapment, acute intraoperative rock-hard eye syndrome, positive vitreous pressure glaucoma, and malignant glaucoma. Other publications were also considered as a potential source of information when referenced in relevant articles. RESULTS: We collected and analyzed 55 articles dated from 1951 to 2016. Acute intraoperative rock-hard eye syndrome is characterized by a very shallow anterior chamber with the absence of suprachoroidal effusion or hemorrhage and no noticeable pathology of the iris-lens diaphragm. It usually occurs during uneventful phacoemulsification, particularly in hyperopic eyes. The pathophysiology of acute fluid misdirection syndrome is based on inappropriate movement of balanced salt solution via the zonular fibers. This syndrome has also been described as occurring from hours to months, or years, after the initial surgery. The pathophysiology of malignant glaucoma is based on similar mechanisms of cilio-lenticular block of aqueous flow leading to the misdirection of aqueous posteriorly into or besides the vitreous gel. Faced with these situations, vitreous decompression is required, preferably with hyaloido-capsulo-iridectomy. In phakic eyes, concomitant cataract extraction would be desirable. CONCLUSIONS: We believe both of these clinical conditions should be considered as one syndrome. We suggest the term acute fluid misdirection syndrome for the cascade of events during phacoemulsification surgery. Chronic fluid misdirection syndrome better describes the nature of malignant glaucoma.

Real-time measurement of needle forces and acute pressure changes during intravitreal injections.

BACKGROUND: The purpose of this study was to use a physiological pressure transducer to measure real-time, continuous pressure changes in an ex vivo study model of porcine eyes to record the amount of force needed for scleral penetration and to measure acute intraocular pressure rise during intravitreal injections. METHODS: A pressure transducer was inserted into the anterior chamber of 30 fresh porcine eyes, and intraocular pressure was measured 2 s prior to intravitreal injection until 2 s after. A force transducer plate was used to insert various gauge needles into the vitreous cavity and the amount of force in Newtons (N) required for scleral penetration was recorded. RESULTS: For scleral perforation, 32- and 30-gauge needles required 0.44 N and 0.45 N, significantly less than larger gauge needles (P < 0.05). Similarly, 27- and 25-gauge needles required more force than smaller gauge needles but less than 19 gauge (P < 0.05). Intraocular pressure increased an average of 64.5 mmHg during intravitreal injection. Two seconds postinjection intraocular pressure readings showed a residual intraocular pressure increase of 11.1 mmHg from pre-injection baseline. CONCLUSION: Real-time continuous recordings of pressure reveal that an instantaneous intraocular pressure spike occurs during intravitreal injection and appears to be separate from the intraocular pressure spike that occurs during needle insertion. This pressure spike is transient and has not been captured by previous methods of intraocular pressure measurement, which rely on single time point measurements. The clinical significance of this brief intraocular pressure spike is unclear and warrants further investigation.

Fluid and structure coupling analysis of the interaction between aqueous humor and iris.

BACKGROUND: Glaucoma is the primary cause of irreversible blindness worldwide associated with high intraocular pressure (IOP). Elevated intraocular pressure will affect the normal aqueous humor outflow, resulting in deformation of iris. However, the deformation ability of iris is closely related to its material properties. Meanwhile, the passive deformation of the iris aggravates the pupillary block and angle closure. The nature of the interaction mechanism of iris deformation and aqueous humor fluid flow has not been fully understood and has been somewhat a controversial issue. The purpose here was to study the effect of IOP, localization, and temperature on the flow of the aqueous humor and the deformation of iris interacted by aqueous humor fluid flow. METHODS: Based on mechanisms of aqueous physiology and fluid dynamics, 3D model of anterior chamber (AC) was constructed with the human anatomical parameters as a reference. A 3D idealized standard geometry of anterior segment of human eye was performed. Enlarge the size of the idealization geometry model 5 times to create a simulation device by using 3D printing technology. In this paper, particle image velocimetry technology is applied to measure the characteristic of fluid outflow in different inlet velocity based on the device. Numerically calculations were made by using ANSYS 14.0 Finite Element Analysis. Compare of the velocity distributions to confirm the validity of the model. The fluid structure interaction (FSI) analysis was carried out in the valid geometry model to study the aqueous flow and iris change. RESULTS: In this paper, the validity of the model is verified through computation and comparison. The results indicated that changes of gravity direction of model significantly affected the fluid dynamics parameters and the temperature distribution in anterior chamber. Increased pressure and the vertical position increase the velocity of the aqueous humor fluid flow, with the value increased of 0.015 and 0.035 mm/s. The results act on the iris showed that, gravity direction from horizontal to vertical decrease the equivalent stress in the normal IOP model, while almost invariably in the high IOP model. With the increased of the iris elasticity modulus, the equivalent strain and the total deformation of iris is decreased. The maximal value of equivalent strain of iris in high IOP model is higher than that of in normal IOP model. The maximum deformation of iris is lower in the high IOP model than in the normal IOP model. CONCLUSION: The valid model of idealization geometry of human eye could be helpful to study the relationship between localization, iris deformation and IOP. So far the FSI analysis was carried out in that idealization geometry model of anterior segment to study aqueous flow and iris change.

[Intraocular pressure measurement inside the anterior chamber: a new technical solution and results]. / Izmerenie davleniya v perednei kamere glaza: novoe tekhnicheskoe reshenie i rezul'taty.

AIM: To develop a new manometric device for intravital measurement of intraocular pressure (IOP) in the anterior chamber and to assess tonometric data reliability, including post-radial keratotomy (RK) measurements. MATERIAL AND METHODS: The experiment was conducted in 2 isolated cadaver eyes, while the clinical study enrolled 20 patients (21 eyes) scheduled for cataract phacoemulsification surgery. Of them, 10 patients (10 eyes) with immature cataract and mild to moderate myopia constituted the control group. The study group consisted of the other 10 patients (11 eyes) with immature cataract, who had undergone RK more than 15 years earlier. The following tonometry methods were used: dynamic bi-directional corneal applanation (ORA, Reichert, USA), dynamic contour tonometry (Pascal tonometer, Zeimer, Switzerland), and rebound tonometry (ICare Pro, Tiolat, Finland). An original device was developed for intravital manometric measurements. RESULTS: Manometric data obtained during the experiment matched the preset pressure in the anterior eye chamber. The median manometry results in the control and study groups were similar and equaled 21.5 and 21.0 mmHg, respectively. Preoperative tonometry readings ranged from 14.9 to 16.5 mmHg in the control group and from 19.7 to 23.3 mmHg - in the study group (with the exception of midperipheral rebound tonometry that showed 15.8 mmHg). CONCLUSION: The developed device can well be used in experimental research. Midperipheral rebound tonometry was found to be the most informative method for post-RK IOP assessment. Manometry results in the study group mismatched tonometry readings in the controls, which might be due to the specifics of equipment calibration and requires further investigation.

Assessment of anterior chamber parameters after cataract surgery by Galilei dual Scheimpflug analyzer.

OBJECTIVE: To quantify the difference between anterior chamber parameters determined by the Galilei dual Scheimpflug analyzer after uneventful cataract surgery in normotensive eyes. METHODS: In this study, 39 eyes of 30 patients (11 men and 19 women) who had uneventful cataract surgery with phacoemulsification were evaluated preoperatively, and at 1 month postoperatively with the Galilei. We investigated the measurements including anterior chamber depth (ACD), anterior chamber angle (ACA), anterior chamber volume (ACV), central corneal thickness (CCT), and the 3-, 5-, and 7-mm corneal thickness (CT) preoperatively and postoperatively. RESULTS: The differences between ACD (P=0.01), ACA (P=0.07), ACV (P=0.01), and 7-mm CT (P=0.01), and intraocular pressure (P=0.03) were statistically significant after the first month of phacoemulsification. However, the differences between CCT (P=0.60), 3-mm CT (P=0.75), and 5-mm (P=0.17) CT were not statistically significant. CONCLUSIONS: After the first month of cataract surgery, a significant increase was observed in ACD, ACV, ACA, and 7-mm CT parameters, which were practically determined by a new noncontact Scheimpflug imagining system.

Fluid dynamics and intraocular pressure using venturi phacoemulsification machine in dogs ex vivo.

OBJECTIVE: To optimize fluid dynamics through measuring intraocular pressure (IOP) in a venturi phacoemulsification machine in dogs. PROCEDURES: In step I, flow and IOP of the test chamber were measured using a pressure transducer with the bottle height (BH) set at 50, 70, 100, and 120 cm and the vacuum from 30 to 450 mmHg. A 19-gauge phaco and a 0.3-mm irrigation/aspiration (I/A) handpiece were used. In step II, flow and IOP were measured in an enucleated canine eye with a 3.0- and a 3.2-mm clear corneal incision (CCI), respectively. IOP was measured using the pressure transducer at a 30-mmHg vacuum to allow corneal deformation, to define the fluidic parameters for preventing surge. RESULTS: Flow was directly proportional to the BH and vacuum, whereas IOP was directly proportional to the BH and inversely to the vacuum. Flow with an I/A handpiece was significantly less than with a phaco handpiece, explaining why IOP with an I/A handpiece was significantly higher than with a phaco handpiece. With the I/A handpiece, vacuum parameters less than 450 mmHg did not result in corneal deformation. IOP with a 3.2-mm CCI was significantly lower than with a 3.0-mm CCI, with the 3.2-mm flow being greater than the 3.0-mm flow. CONCLUSIONS: BH during the I/A stage could be reduced to avoid unnecessary stress on the canine eye when using a venturi system. Although phacoemulsification with a 3.2-mm CCI could induce lower IOP, a 3.0-mm CCI might lessen the irrigation flow stress on the eye.

Disease progression in iridocorneal angle tissues of BMP2-induced ocular hypertensive mice with optical coherence tomography.

PURPOSE: The goal of the present study was to test for the first time whether glaucomatous-like disease progression in a mouse can be assessed morphologically and functionally with spectral domain optical coherence tomography (SD-OCT). METHODS: We monitored progressive changes in conventional outflow tissues of living mice overexpressing human bone morphogenetic protein 2 (BMP2), a model for glaucoma. Intraocular pressure (IOP) and outflow tissue morphology/Young's modulus were followed in mice for 36 days with rebound tonometry and SD-OCT, respectively. Results were compared to standard histological methods. Outflow facility was calculated from flow measurements with direct cannulation of anterior chambers subjected to three sequential pressure steps. RESULTS: Overexpression of BMP2 significantly elevated IOP in a biphasic manner over time compared to mice that overexpressed green fluorescent protein in outflow cells and naïve controls. SD-OCT revealed changes in outflow tissues overexpressing BMP2 that corresponded with the timing of the IOP phases and decreased outflow facility. In the first phase, the angle was open, but the trabecular meshwork and the cornea were thickened. OCT detected increased trabecular meshwork stiffness after provocative IOP challenges of the BMP2 eyes, which corresponded to increased collagen deposition with transmission electron microscopy. In contrast, the angle was closed in the second phase. IOP elevation over 36 days due to BMP2 overexpression resulted in significant retinal ganglion cell and axon loss. CONCLUSIONS: Although not a feasible open-angle glaucoma model, the BMP2 mice were useful for demonstrating the utility of SD-OCT in following disease progression and differentiating between two forms of ocular pathology over time that resulted in ocular hypertension.

Light-dark changes in iris thickness and anterior chamber angle width in eyes with occludable angles.

BACKGROUND: The purpose of this study was to investigate and measure light-dark changes in iris thickness (IT) and anterior chamber angle width in eyes with occludable angles and open angles by using anterior segment optical coherence tomography (AS-OCT). METHODS: We examined 153 eyes of 153 Japanese patients with primary angle closure suspect, primary angle closure, primary angle closure glaucoma, or primary open angle glaucoma. AS-OCT was used to determine pupil diameter, IT, angle opening distance at 500 µm (AOD500), and trabecular-iris space area at 500 µm (TISA500) in each quadrant of the anterior chamber angle (superior, inferior, temporal, and nasal) under light and dark conditions. RESULTS: In the angle closure cases, IT, AOD500 and TISA500 in the dark varied significantly among the four quadrants (P < 0.05, analysis of variance). In contrast, in the open angle cases, IT, AOD500 and TISA500 in the dark did not differ significantly among the four quadrants. In the angle closure cases and the open angle cases, significant negative associations were found between IT difference [IT(light)-IT(dark)] and AOD500 difference [AOD500(light)-AOD500(dark)] (R = -0.411, P < 0.001 and R = -0.501, P = 0.001, respectively) and between IT difference and TISA500 difference [TISA500(light)-TISA500(dark)] (R = -0.475, P < 0.001 and R = -0.462, P = 0.002, respectively). CONCLUSION: Our results suggest that thickening of the iris root under dark conditions is related to the mechanism of primary angle closure. It is important to analyze both the angle structure and peripheral IT in each quadrant.

Evaluation of corneal changes with accommodation in young and presbyopic populations using Pentacam High Resolution Scheimpflug system.

BACKGROUND: To evaluate the changes occurring in the cornea with accommodation in young and presbyopic people. DESIGN: Prospective study. PARTICIPANTS: Twenty-three young and 15 presbyopic emmetropic volunteers. METHODS: The Pentacam High Resolution system was used to obtain data on the anterior eye segments of emmetropic volunteers in unaccommodated (with an accommodation stimulus of 0.0 D) and accommodated (with an accommodation stimulus of 5.0 D for the young volunteers and 1.0 D for the presbyopic) states. MAIN OUTCOME MEASURES: Anterior and posterior corneal axial curvature, corneal volume, corneal aberration, anterior chamber depth and anterior chamber volume were evaluated. RESULTS: A significant decline in anterior chamber depth and anterior chamber volume was induced by accommodation in both young and presbyopic volunteers. There was a small but statistically significant change in corneal volume within 3.0, 5.0 and 7.0 mm diameters during accommodation in both groups. The changes in the corneal curvature map were significant with accommodation in both groups, although individual variations were found in anterior and posterior corneal axial curvature. Moreover, the decreased higher order aberrations were found in both anterior and entire cornea. In particular, spherical aberration was changed in the young group with 5.0 D accommodation stimulus. CONCLUSION: This study showed that accommodation can influence the corneal shape and curvature, and, especially, decreased corneal high-order aberrations. Although the modification in corneal shape was small, it produced variations in higher order aberrations with accommodation that may be beneficial for visual performance in near vision.

An assessment of the ocular safety of excipient maleic acid following intravitreal injection in rabbits.

Maleic acid was formulated in 0.7% saline and injected intravitreally in rabbits in order to evaluate ocular safety and tolerability. Maleic acid was formulated within a narrow pH range (2-3), administered in a fixed volume (100 µl), and concentrations ranged from 0.00 to 2.00 mg/eye (0.00 to 12.30 mM vitreous). Ocular evaluations were conducted at 2, 4, and 8 days post injection. Ocular irritation responses were observed at doses from 0.50 mg/eye (3.07 mM vitreous) to 2.00 mg/eye (12.30 mM vitreous) and included conjunctival redness and scleral swelling. Chemosis was observed at 2.00 mg/eye (12.30 mM vitreous). Funduscopic evaluations revealed enlarged retinal blood vessels and optic disk swelling at doses ≥1.50 mg/eye (9.22 mM vitreous), retinal folds and retinal discoloration at 2.00 mg/eye (12.30 mM vitreous). Histopathologic evaluations on days 4 and 8 post injection revealed retinal degeneration at doses ≥1.0 mg/eye (6.15 mM vitreous), conjunctival inflammation at doses ≥1.5 mg/eye (9.22 mM vitreous), and retinal pigment epithelial hypertrophy, optic nerve demyelination, anterior chamber fluid, and conjunctival fibrosis at 2.00 mg/eye (12.30 mM vitreous) maleic acid. The data suggest that maleic acid formulations at ≥1.00 mg/eye (6.15 mM vitreous) were not suitable for intraocular indications.

Mathematical and computer simulation modelling of intracameral forces causing pupil block due to air bubble use in Descemet's Stripping Endothelial Keratoplasty: the mechanics of iris buckling.

BACKGROUND: Descemet's Stripping Endothelial Keratoplasty has been associated with a steep learning curve. Angle closure post Descemet's Stripping Endothelial Keratoplasty has been reported, either because of air posterior to the iris causing iridocorneal adhesions, or by air anterior to the iris causing pupillary block. The mechanics of floppy iris syndrome and pupil block have not been discussed. METHODS: We evaluated the various forces competing within the anterior chamber via mathematical modelling and computational simulation, and considered the influence of floppy iris on pupil block glaucoma. RESULTS: Energy formulae suggest a critical pressure value will maintain normal anterior chamber relationships, above which abnormal iris buckling may occur. This mechanical instability can be influenced intraoperatively by abnormal iris properties and intracameral forces (such as air). This critical value is lowered if the patient has a floppy iris (because of a lower elastic modulus, a mechanical measure of iris rigidity). To demonstrate this mathematical concept, a 3-D computational model was built. Simulations show that, as intracameral pressure increases, the iris ring can buckle into predictable modes of shapes. CONCLUSION: This model shows how iris buckling could occur with an intracameral air bubble leading to posterior iris displacement and mechanical pupil block. It also shows that abnormal iris behaviour in IFIS is consistent with the expected predicted buckling of an elastic disc.

Intraocular Pressure and Its Relation to Ocular Geometry: Results From the Gutenberg Health Study.

Purpose: The purpose of this study was to investigate the association between intraocular pressure (IOP) and ocular geometry. Methods: The Gutenberg Health Study is a population-based cohort study in Mainz, Germany. Study participants underwent a comprehensive ophthalmologic examination including noncontact tonometry, objective refraction, optical biometry, and Scheimpflug imaging of the anterior segment at the first 5-year follow-up examination (in 2012-2017). Multivariable linear regression analysis was carried out to determine associations of IOP and geometric parameter of the human phakic eye, namely central corneal thickness (CCT), corneal curvature, anterior chamber depth (ACD), lens thickness, and axial length. In addition, the relationship of IOP and the anterior chamber angle (ACA) width was analyzed. Results: There were 6640 participants with phakia (age 57.3 ± 10.2 years, 49.1% women) that were included in this cross-sectional analysis. Mean IOP was 14.8 ± 2.9 mm Hg in the right eyes and 14.9 ± 2.9 mm Hg in the left eyes. IOP increased with higher CCT, greater posterior segment length, higher age (all P < 0.001), thicker lens (P = 0.003), and female sex (P = 0.05), whereas the ACD was not associated with higher IOP. The IOP increased with a narrower ACA in univariable analysis (P < 0.001), but not in adjusted analysis in subjects with an open angle. Conclusions: IOP values are related to ocular geometry, as shown in this population-based study on Caucasian subjects. Thus, knowledge of the architecture of the eye is an important factor when measuring IOP. Longitudinal evaluation will analyze whether some of these parameters are also risk factors for the development of glaucoma.

Differences in outflow channels between two eyes of unilateral primary congenital glaucoma.

PURPOSE: Primary congenital glaucoma (PCG) occurs in only one eye in some patients. We aimed to characterize anatomical features of the angle and Schlemm's canal (SC) in vivo among fellow eyes of patients with unilateral primary congenital glaucoma. METHODS: Both eyes of 33 children with unilateral PCG and 30 healthy, age-matched children, old enough to co-operate were analysed using high-resolution anterior segment spectral domain (SD) OCT. Subgroup analysis was done for the presence/absence of angle dysgenesis as defined by the presence of abnormal tissue/hyper-reflective membrane within angle recess and/or the absence of SC. Other anatomical landmarks differentiating the fellow eyes from eyes with glaucoma were also evaluated and compared with healthy subjects. RESULTS: The presence of abnormal tissue at the angle and/or a hyper-reflective membranous structure covering the meshwork was seen in all affected PCG eyes (100%) and in 21 (63%) unaffected fellow eyes; p = 0.001. The SC could be seen in 8 (24%) affected in comparison with 29 (88%) fellow unaffected eyes; p = 0.001. The ASOCT scans of 54 (90%) healthy eyes and 3 (9%) fellow PCG eyes revealed a direct communication of anterior portion of the SC with the anterior chamber. Among the fellow eyes, a communication of the supraciliary space with anterior chamber could be discerned in 26 eyes (79%). CONCLUSIONS: Despite angle dysgenesis, outflow channels such as the uveoscleral or a direct communication of SC with the anterior chamber play a role in preventing the development of glaucoma in fellow eyes of unilateral PCG.

Delayed vitreous prolapse after cataract surgery: clinical features and surgical outcomes.

This study investigates the etiology and clinical features of delayed vitreous prolapse after cataract surgery and evaluates the long-term surgical and visual outcomes. Consecutive patients with vitreous prolapse into the anterior chamber occurring ≥ 3 months after cataract surgery at two hospitals between December 2006 and June 2020 were retrospectively reviewed. The primary outcome was associated ophthalmological events that triggered delayed vitreous prolapse. Secondary outcomes included long-term visual and subjective symptom changes after treatment. Among 20 eyes (20 patients), all had visual symptoms, the most common being blurry vision (12 patients; 60%). Five (25%) were detected after YAG laser capsulotomy, three (15%) had a history of intraocular lens(IOL) implantation in sulcus due to intraoperative posterior capsular tears, three (15%) had prolapsed vitreous alongside dislocated IOLs, and three (15%) were aphakic after previous cataract surgeries. After surgical treatment, the mean corrected distance visual acuity improved from 20/50 to 20/31(P = 0.02) and the mean preoperative intraocular pressure (IOP) that was 26.4 mmHg decreased to 15.6 mmHg, remaining stable until the last follow-up. All reported symptoms were relieved. YAG laser capsulotomy or a history of defective posterior capsule from iatrogenic causes may trigger delayed vitreous prolapse. The long-term outcomes were favorable, particularly after posterior vitrectomy, with improved IOP control and symptom resolution.

Intraoperative fracture of phacoemulsification sleeve.

BACKGROUND: We describe a case of intraoperative fracture of phacoemulsification sleeve during phacoemulsification surgery. CASE PRESENTATION: Phacoemulsification surgery was performed in the left eye of a 58-year-old lady with grade II nuclear sclerosis & grade I cortical cataract. Towards the end of quadrant removal, there was anterior chamber instability with impaired followability of nuclear fragments. The distal part of the fractured sleeve remained inside the anterior chamber upon removal of the phacoemulsification probe. The retained sleeve was retrieved with a pair of forceps through the corneal incision site, which did not require widening. There was no missing fragments retained intraocularly and the patient had an uneventful recovery with vision of 20/25 at three months post-operatively. CONCLUSION: Phacoemulsification sleeve fracture is an uncommon complication. With early identification of this condition and proper management, major complications can be avoided.