Effect of intravitreal injections and volume changes on intraocular pressure: clinical results and biomechanical model

VIVEX: A Formula for Calculating Individual Vitreous Volume: A New Approach Towards Tailored Patient Dosing Regime in Intravitreal Therapy

INTRODUCTION

Personalized medicine and patient-tailored drug dosing have been substantiated through thousands of clinical studies, demonstrating their safety and efficacy. The principle: "as much as necessary, as little as possible" is widely spread. Quantities and doses are therefore adjusted individually. This is not the case for intravitreal injections in the context of retinal diseases. Intravitreal injections are not adjusted in relation to the vitreous volume. The vitreous body is described as "approx. 4 cm3" in the literature.

METHODS

In this retrospective observational study, we included 72 eyes of patients who had undergone magnetic resonance imaging (MRI) of the orbit and biometry measurements of the anterior chamber depth (ACD) and axial length. After segmentation of the volume data, the vitreous volume was extracted by voxel integration, and a simple prediction model was derived to determine the vitreous volume from the axial length (AL) measurement with AL3·π/6·(0.76 + 0.012·(AL-24). This is the volume of a sphere AL3·π/6 and a correction term 0.76 + 0.012·(AL-24) to account for the portion of the vitreous in the entire globe and the proportional increase of the vitreous portion for long (myopic) eyes.

RESULTS

Emmetropic eyes with an axial length of 22.50-23.50 mm had a vitreous volume of around 4.5-5.5 cm3. Myopic eyes with an axial length of 30.00 mm had a calculated vitreous volume of 9.0-10.0 cm3. Hypermetropic eyes with an axial length of 20.00 mm showed a vitreous volume of 3.0-4.0 cm3.

CONCLUSIONS

By implementing the new calculation formula on the IOLCON website, it will be easy to get the exact individual vitreous volume. The data could be used by retinal surgeons prior to surgery. The knowledge of anatomical dimensions and exact individual vitreous volume seems to be important for gas and silicone oil fillings. With the newly derived knowledge, multicentric studies can evaluate the impact of the dose in intravitreal therapies. Patient-tailored dosing could prevent side effects and improve effectiveness.

Can intravitreal injections with higher volume cause higher intraocular eye pressure? Considerations for anti-complement injections in normal and glaucomatous eyes

The approval of Syfovre® (pegcetacoplan) and Iverzay® (avacincaptad pegol) for the treatment of geographic atrophy (GA) marks a significant advancement in retinal disease therapy, offering both complement 3 and complement 5 inhibitors. With this breakthrough, an increase in intravitreal injections (IVI) is expected to treat GA, raising questions about potential effects on intraocular pressure (IOP). This concern is exacerbated by the larger injection volume required for GA treatment, potentially impacting IOP. Previous studies have shown that IVI can lead to a temporary increase in IOP with a 0.05 ml injection. This transient elevation is challenging to manage with glaucoma drops, and a preventive approach, such as paracentesis immediately before IVIs, may be more effective. Despite concerns, clinical significance and long-term effects of IOP changes with a 0.05 ml injection remain uncertain. To address these concerns, routine evaluations including macular optical coherence tomography (OCT), fundus autofluorescence, IOP measurements, and retinal nerve fiber layer OCT before the first IVI with avacincaptad pegol and pegcetacoplan are recommended to detect potential changes early. Further research is needed to determine the extent to which IOP changes impact GA patients and whether cumulative effects occur with repeated IVIs, especially in those with additional eye conditions.

The Effect of Dorzolamide-timolol Eye drop on Intraocular Pressure Change in Intravitreal Ranibizumab Injected Patients

PURPOSE

The objective of the study was to examine the effect of dorzolamide-timolol (DT) eye drop used before intravitreal ranibizumab (IVR) injection on intraocular pressure (IOP) change.

METHODS

50 eyes of 50 patients who received DT eye drops 1 h before IVR injection due to diabetic retinopathy and macular edema were considered Group 1, and 50 eyes of 50 patients who did not receive DT eye drops were considered Group 2. Those patients who had previously undergone intravitreal injection had intraocular surgery, and used any eye drops were not included in the study. Before the injection, IOP values were measured with a Tonopen contact handheld tonometer before the blepharostat was placed (BIOP), after the blepharostat was placed (AIOP), and at the 1st min after the injection (IIOP).

RESULTS

There were 25 males and 25 females in Group 1 and 25 males and 25 females in Group 2; the mean age was 65.66 ± 9.94 years in Group 1 and 65.54 ± 7.43 years in Group 2 (P = 0.98). In Group 1, BIOP was 18.91 ± 18.91, AIOP was 21.62 ± 6.16 mmHg, and IIOP was 49.21 ± 10.95 mmHg. In Group 2, BIOP was 20.18 ± 4.19 mmHg, AIOP was 24.60 ± 4.90 mmHg, and IIOP was 49.96 ± 9.72 mmHg. IIOP-BIOP difference was 30.30 ± 9.85 mmHg in Group 1 and 29.78 ± 9.33 mmHg in Group 2 and the difference was not statistically significant (P = 0.78). In Group 1, the IIOP-AIOP difference was 27.58 ± 10.60 mmHg and in Group 2, 25.36 ± 10.46 mmHg. The difference between IIOP and AIOP was not statistically significant (P = 0.27).

CONCLUSION

The use of topical DT eye drops before IVR injection does not affect the intraocular pressure change.

Optical coherence tomography and Scheimpflug imaging of the iridocorneal angle following intravitreal injection of different medications: A longitudinal analysis

PURPOSE

Intravitreal injection of medications induces a sudden increase in posterior segment volume and pushes iris plane anteriorly to narrow iridocorneal angle. The aim of this study to follow and define longitudinal course of these changes following intravitreal injection of 3 different anti-vascular endothelial growth factor (VEGF) medications or dexamethasone implant.

MATERIALS AND METHODS

This prospective, longitudinal study included 89 eyes of 89 patients that had an intravitreal injection of bevacizumab (n = 20) or ranibizumab (n = 26) or aflibercept (n = 22) or dexamethasone implant (n = 21). All the participants had a detailed ophthalmological examination including anterior segment optical coherence tomography (AS-OCT) and Scheimpflug imaging of the iridocorneal angle, evaluation of anterior chamber depth (ACD), axial length with optical biometry and endothelial cell counts with specular microscopy just before the injection, at post-injection day 1, and post-injection 1st month.

RESULTS

Iridocorneal angle became significantly wider following intravitreal injection of dexamethasone implant at nasal and temporal quadrants at the post-injection 1st month both in AS-OCT (p = 0.006, p = 0.002, respectively) and Scheimpflug imaging (p = 0.003, p = 0.004, respectively). Small changes were observed in iridocorneal angle following anti-VEGF injections but these small could not be confirmed in both imaging techniques. There were also no changes in ACD, axial length and endothelial counts in all groups.

CONCLUSION

Dexamethasone implants induced widening of iridocorneal angle that persisted at the post-injection 1st month both at nasal and temporal quadrants. However, intravitreal injection of anti-VEGF agents did not have a comparable effect on iridocorneal angle.

A Review of Corneal Biomechanics and Scleral Stiffness in Topical Prostaglandin Analog Therapy for Glaucoma

PURPOSE

The mechanism of action underlying prostaglandin analog (PGA) therapy involves changes in the expression of different metalloproteases to increase permeability of the sclera and allow increased aqueous humor outflow through this alternative drainage pathway. This alteration of structure impacts cornea/scleral biomechanics and may introduce artifact into the measurement of intraocular pressure (IOP) in the clinical setting.

METHODS

A literature search reviewing the impact of PGA therapy on corneal and scleral biomechanics was conducted including basic studies, clinical studies with treatment naïve patients, and a clinical study examining the cessation of PGA therapy. Additional literature including engineering texts was added for greater clarity of the concepts underlying ocular biomechanics.

RESULTS

One study with an animal model reported significant corneal stiffening with PGA treatment. Most longitudinal clinical studies examining the effects of initiation of PGA therapy in PGA naïve subjects failed to report biomechanical parameters associated with stiffness using the Corvis ST and only included those parameters strongly influenced by IOP. One study reported a significant reduction in scleral stiffness with IOP as a co-variate, highlighting the need to account for the effects of IOP lowering when assessing clinical biomechanics. The report of cessation of PGA therapy on corneal biomechanics showed no change in corneal compensated IOP after 6 weeks, raising the question of reversibility of the PGA-induced structural alteration.

CONCLUSIONS

Given that the findings in several clinical studies may merely reflect a reduction in IOP, further studies are warranted using Corvis ST parameters associated with corneal and scleral stiffness. The gold standard for IOP measurement in the clinical setting is Goldmann applanation tonometry, a technique previously shown to be affected by corneal stiffness. Since PGA therapy has been reported to alter not only scleral biomechanics, but also corneal biomechanics, it is essential to consider alternative tonometry technologies in the clinic.

Tunable alginate hydrogels as injectable drug delivery vehicles for optic neuropathy

Many disease pathologies, particularly in the eye, are induced by oxidative stress. In particular, injury to the optic nerve (ON), or optic neuropathy, is one of the most common causes of vision loss. Traumatic optic neuropathy (TON) occurs when the ON is damaged following blunt or penetrating trauma to either the head or eye. Currently, there is no effective treatment for TON, only management options, namely the systematic delivery of corticosteroids and surgical decompression of the optic nerve. Unfortunately, neither option alleviates the generation of reactive oxygen species (ROS) which are responsible for downstream damage to the ON. Additionally, the systemic delivery of corticosteroids can cause fatal off‐target effects in cases with brain involvement. In this study, we developed a tunable injectable hydrogel delivery system for local methylene blue (MB) delivery using an internal method of crosslinking. MB was chosen due to its ROS scavenging ability and neuroprotective properties. Our MB‐loaded polymeric scaffold demonstrated prolonged release of MB as well as in situ gel formation. Additionally, following rheological characterization, these alginate hydrogels demonstrated minimal cytotoxicity to human retinal pigment epithelial cells in vitro and exhibited injection feasibility through small‐gauge needles. Our chosen MB concentrations displayed a high degree of ROS scavenging following release from the alginate hydrogels, suggesting this approach may be successful in reducing ROS levels following ON injury, or could be applied to other ocular injuries.

Accuracy of intravitreal injection volume for aflibercept pre-filled syringe and BD Luer-Lok one-milliliter syringe

Background

To evaluate the accuracy of intravitreal injection volume of the pre-filled syringe (PFS) in which aflibercept is packaged compared to the BD Luer-Lok 1-mL syringe.

Methods

Ophthalmologists injected their typical intravitreal volume for aflibercept using either the PFS or BD Luer-Lok 1-mL syringe for 5 times each. The injected fluid was weighed using a micro-scale and converted to volume. The volume of fluid injected was also evaluated when the 0.05 mL line on the PFS was lined up to the tip or base of the dome-shaped plunger.

Results

Injection volume was measured for 12 physicians. The average injected fluid volume was 74.22 ± 15.87 µL for PFS and 53.42 ± 4.61 µL for the BD Luer-Lok 1-mL syringe (p < 0.0001). The average deviation in volume injected for the PFS was higher compared to the BD Luer-Lok 1-mL syringe (11.36 µL vs. 3.35 µL, p < 0.0001). When the PFS was lined up with the tip of the dome-shaped plunger at the 0.05-mL line, the average injected volume was 71.03% higher.

Conclusions

The intravitreal injection volume and variability using the new PFS were significantly higher than the volume injected using the BD Luer-Lok 1-mL syringe previously used, potentially leading to higher rates of visually significant elevation of intraocular pressures.

Efficacy of Combined Vitrectomy with Intravitreal Corticosteroid Injection for Idiopathic Epiretinal Membrane Removal on Anatomical and Functional Outcomes: A Meta-analysis

BACKGROUND

Macular edema can be a cause of visual loss in eyes undergoing vitrectomy with epiretinal membrane(ERM) peeling.

OBJECTIVE

To evaluate the efficacy of combined vitrectomy with intravitreal corticosteroid injection for ERM.

METHODS

We conducted a systematic literature review by searching PubMed, Embase, and Medline up to December 2020 for studies that evaluated the effect of intravitreal corticosteroid injection during vitrectomy for ERM. Follow-up data on postoperative best-corrected visual acuity (BCVA) and central macular thickness (CMT) were collected and pooled using the standard mean deviation (SMD) with the corresponding 95% confidence interval (CI). Heterogeneity was statistically quantified using I2 statistics, and a meta-analysis was performed using a random-effects model.

RESULTS

Eight studies provided data on a total sample of 443 eyes. The meta-analysis revealed that concomitant intravitreal corticosteroid administration during vitrectomy contributed to a significant reduction in CMT than vitrectomy alone at 3 months after operation (pooled SMD = -0.353; 95% CI, -0.594 to -0.111; p = 0.004). However, between the two groups, no significant difference was found in CMT reduction at 1 and 6 months after operation and in postoperative BCVA improvement at 1, 3, and 6 months after operation.

CONCLUSION

Combined treatment with vitrectomy and intravitreal corticosteroid injection may accelerate CMT reduction 3 months after ERM surgery. However, it did not result in a significant change in CMT and BCVA compared with vitrectomy alone at the end of follow-up.

Acute and subacute macular and peripapillary angiographic changes in choroidal and retinal blood flow post-intravitreal injections

Whether post injectional acute intraocular pressure (IOP) increase is associated with decreased peripapillary and macular perfusion is still under debate. Here, we investigated early changes in the choroidal and retinal blood flow using OCTA imaging in a cohort of patients undergoing anti-VEGF intravitreal injections (IVI) for macular edema following retinal vein occlusion and diabetic retinopathy. In this prospective single-center, observational study, the pre- and post-IVI changes in retinal perfusion were examined via assessment of vessel length density (VLD) and vessel density (VD) in deep and superficial capillary segmentations (DCP and SCP), foveal avascular zone (FAZ) in SCP, as well as flow signal deficits in the choriocapillaris segmentation. Mean IOP significantly changed over the study course (p = 0.000; ANOVA). Measurements at 5 min post-IVI (33.48 ± 10.84 mmHg) differed significantly from baseline (17.26 ± 2.41 mmHg, p = 0.000), while measurements from one day, one week, and one-month post-IVI did not (p = 0.907, p = 1.000 and p = 1.000 respectively). In comparison to baseline, no changes in OCTA parameters, including FAZ, VD, VLD, and FV, were detected 5 min post-IVI. No significant alterations in OCTA parameters were observed during study course. Increased IOP spikes were detected post-IVI; however, no potential permanent ischemic retinal damage was suspected.

Evaluation of intraocular pressure change and anterior segment parameters after intravitreal bevacizumab injection - Cannula size matters

PURPOSE:

To determine the changes in intraocular pressure (IOP) and anterior chamber parameters following intravitreal bevacizumab injection with different sizes of cannulas.

METHODS:

This clinical trial was conducted with 70 eyes of 70 patients who received an intravitreal injection of bevacizumab with 26 G (Group 1) or 30 G (Group 2) needle. Preinjection and postinjection 30^th-min IOP and pentacam measurements were obtained. Anterior chamber depth (ACD), anterior chamber volume (ACV), central corneal thickness (CCT), corneal volume (CV), and iridocorneal angle (ICA) measurements were evaluated in pentacam.

RESULTS:

Preinjection mean IOP values in Group 1 and 2 were 14.7 ± 3.29 mm Hg and 15.1 ± 2.87 mm Hg, respectively. Postinjection mean IOP in Group 1 was 16.8 ± 6.24 mm Hg and in Group 2 was 20.3 ± 3.66 mm Hg. Postinjection mean IOP values were significantly higher than preinjection values in both groups (Group 1 P < 0.005 and Group 2 P < 0.001). IOP change was significantly higher in Group 2 after injection (P < 0.05). In both groups, the change in IOP found to be more significant in phakic eyes than pseudophakic eyes (Group 1 P < 0.001, Group 2 P < 0.001). CCT and CV were significantly higher in both groups 30 min after the injection than preinjection (Group 1 and Group 2; P < 0.01). In Group 2 ACD, ACV and ICA values were significantly lower than preinjection values (P < 0.05).

CONCLUSION:

Needle bore size is an important parameter that influences anterior segment parameters and IOP change in the intravitreal injection. IOP rise and anterior segment changes are more prominent with a thinner cannula.

Real-time measurement of intraocular pressure variation during automatic intravitreal injections: An ex-vivo experimental study using porcine eyes

PURPOSE

To measure needle insertion force and change in intraocular pressure (IOP) in real-time during intravitreal injection (IVI). The effects of needle size, insertion speed, and injection rate to IOP change were investigated.

METHODS

Needle insertion and fluid injection were performed on 90 porcine eyeballs using an automatic IVI device. The IVI conditions were divided according to needle sizes of 27-gauge (G), 30G, and 33G; insertion speeds of 1, 2, and 5 mm/s; and injection rates of 0.01, 0.02, and 0.05 mL/s. Insertion force and IOP were measured in real-time using a force sensor and a pressure transducer.

RESULTS

The peak IOP was observed when the needle penetrated the sclera; the average IOP elevation was 96.3, 67.1, and 59.4 mmHg for 27G, 30G, and 33G needles, respectively. An increase in insertion speed caused IOP elevation at the moment of penetration, but this effect was reduced as needle size decreased: 109.8-85.9 mmHg in 27G for 5-1 mm/s (p = 0.0149) and 61.8-60.7 mmHg in 33G for 5-1 mm/s (p = 0.8979). Injection speed was also related to IOP elevation during the stage of drug injection: 16.65 and 11.78 mmHg for injection rates of 0.05 and 0.01 mL/s (p < 0.001).

CONCLUSION

The presented data offers an understanding of IOP changes during each step of IVI. Slow needle insertion can reduce IOP elevation when using a 27G needle. Further, the injection rate must be kept low to avoid IOP elevations during the injection stage.

Intraocular pressure and injection forces during intravitreal injection into enucleated porcine eyes

Injection of biological molecules into the intravitreous humor is of increasing interest for the treatment of posterior segment eye diseases such as age-related degenerative macular degeneration. The injection volume is limited by an increase in intraocular pressure (IOP) and 50-100 µL are typically used for most intravitreally (IVT) applied commercial products. Direct measurement of IOP is difficult and has not been studied dependent on solution properties and injection rates. We used an instrumental set-up to study IOP ex vivo using healthy enucleated porcine eyes. IOP was determined as a function of injection volume for viscosities between 1 and 100 mPas, injection rates of 0.1, 1, and 1.5 mL/min, and needle length and diameter (27/30G and 0.5/0.75″) using Dextran solutions. IOP increased exponentially for injection volumes larger than 100 µL. We did not observe differences in IOP dependent on viscosity, injection rate, and needle diameter. However, variability increased significantly for injection volumes larger than 100 µL and, unexpectedly, declined with higher viscosities. We demonstrate that the exponential increase in IOP is not reflected by injection force measurements for typical configurations that are used for IVT application. The present findings may guide injection volumes for intravitreal injection and inform injection force considerations during technical drug product development.

Double Eyelid Tape Wear Affects Anterior Ocular Health among Young Adult Women with Single Eyelids

Many East Asians apply double eyelid tape to create the double eyelid effect temporarily as a means of increasing their beauty. This study evaluated the effects of four-week wear of double eyelid tape on anterior ocular health in young adult women with single eyelids. Twenty-nine participants who met the inclusion criteria were recruited. The participants’ anterior ocular health was examined including blinking characteristics (blink pattern and blink rate), ocular surface health (presence of corneal abrasion, corneal staining, conjunctival staining, corneal curvatures, meibomian gland dysfunction), tear break up time, intraocular pressure, and subjective comfort level. Participants were required to apply the double eyelid tape for at least eight hours a day and five days a week for four weeks. The parameters were re-measured at the end of each week. There was a significant increase in conjunctival staining, corneal staining, and meibomian gland dysfunction, with a significant reduction in tear break-up time and intraocular pressure. By week 3, all participants had incomplete blinks. There was no significant change in symptoms and subjective comfort level reported. Therefore, patients and eye care practitioners should be aware of the potential implications of double eyelid tape wear on ocular health, with no significant change in subjective comfort.

Late-onset angle closure in pseudophakic eyes with posterior chamber intraocular lenses

Two patients presented with angle closure many years after cataract extraction. The first patient presented with acute intraocular pressure (IOP) elevation and closed iridocorneal angle that resolved with a laser iridotomy. The second patient presented with an insidious course of high IOP and progressive narrowing of the iridocorneal angle, ultimately requiring a pars plana vitrectomy and glaucoma valve implant, with subsequent normalization of pressure and angle anatomy. Although rare, angle closure in eyes with posterior chamber intraocular lenses is a dangerous complication that can occur many years after cataract extraction. Retained lens fragments, and perhaps repeated intravitreal injections, might place susceptible patients at risk.

Non-arteritic anterior ischemic optic neuropathy after intravitreal aflibercept for age-related macular degeneration

PURPOSE

To report a case of non-arteritic anterior ischemic optic neuropathy (NAION) after intravitreal injection in a patient with a history of fellow-eye NAION.

METHODS

Observational case report.

RESULTS

An 82-year-old woman with a history of fellow eye NAION developed an inferior visual field defect 1 day after an intravitreal aflibercept injection for neovascular age-related macular degeneration (AMD). She was found to have optic disc edema and an inferior altitudinal defect, consistent with NAION. The mechanism may have involved compromised perfusion to the optic nerve head related to elevated intraocular pressure or vasoconstriction due to anti-vascular endothelial growth factor activity.

CONCLUSIONS

NAION is a rare complication of intravitreal injection and may be related to post-injection elevation in IOP. Monitoring of IOP post-injection with low-threshold for pre-injection aqueous suppression or post-injection anterior chamber paracentesis for persistently elevated IOP is recommended in patients with a history of NAION.

Ziv-aflibercept: A cost-effective, off-label, highly potent antagonist of vascular endothelial growth factor

Ziv-aflibercept (Zaltrap^® ), a recombinant fusion protein that binds diffusible vascular endothelial growth factor (VEGF), is approved for the treatment of metastatic colorectal carcinoma. Its molecular structure is the same as aflibercept (Eylea^® ), thus making it an attractive option for the off-label treatment of chorioretinal vascular conditions. Ziv-aflibercept is distributed in 4 and 8 ml vials for intravenous use, and its cost after compounding is similar to bevacizumab. Studies with retinal pigment epithelium cytotoxicity, animal histologic sections and electroretinography have demonstrated its safety, and mathematical modelling combined with over four dozen clinical publications from different ophthalmic centres throughout the world attest to its efficacy. No appreciable differences in visual or anatomic outcomes between 1.25 mg (0.05 ml) and 2.5 mg (1.0 ml) doses have been noted. The long duration of action combined with the low cost make ziv-aflibercept an attractive anti-VEGF treatment option, especially in low- and middle-income countries where its popularity is increasing.

Acute Retinal Necrosis: Virological Features Using Quantitative Polymerase Chain Reaction, Therapeutic Management, and Clinical Outcomes

PURPOSE

To evaluate outcomes of patients treated with intensive intravitreal therapy and to describe the evolution of quantitative real-time polymerase chain reaction (qPCR) in patients treated for acute retinal necrosis (ARN) syndrome.

DESIGN

Retrospective observational case series.

METHODS

This study included 25 eyes of 24 patients with ARN who were treated and followed up in 2 departments of ophthalmology in Lyon, France. Assessed outcomes included qPCR viral load profile during treatment, number of antiviral intravitreal injections (IVT), retinal detachment rate, and best-corrected visual acuity.

RESULTS

Final visual acuity was 20/200 or less in 20% of cases; the rate of retinal detachment was 16%. Viral load kinetics changed in 3 phases: a first plateau period that was not consistent, a logarithmic decrease phase, and a negativation phase. Mean decay of the logarithm of the viral load was estimated at 0.076 per day; mean time of negativation was 56.1 days. Median IVT number was 9 (range, 0-28). Ten patients were treated with injections until the viral load was undetectable. Resistance to acyclovir was observed in a patient with a prolonged initial plateau of the viral load.

CONCLUSIONS

Numerous and prolonged IVTs, used as adjunctive therapy, could improve the prognosis of treated patients by decreasing the risk of retinal detachment and improving visual acuity. QPCR enables monitoring of the response to treatment and can provide evidence for resistance to antiviral treatment by enabling the detection of cases with a prolonged initial plateau of viral load.

Physiologically based ocular pharmacokinetic modeling using computational methods

By explicitly representing ocular anatomy, computational fluid dynamic simulation methods model drug mass transport both within and between ocular tissue regions, providing reliable animal-to-human translation of bioavailability. Here, we apply physiologically based models to simulate ocular drug administration. A non-anatomical model is used that applies a simple theorem for calculating ocular bioavailability from a topical dose. A computational fluid dynamic model is also described that incorporates ocular physiology in anatomical models for rabbit, monkey and man. This second method applies material properties and boundary conditions for various tissues enabling simulation of fluid flows, pressures, temperatures, convection, and drug advection following various modes of administration. The method provides a regional distribution with a given tissue not available using standard compartmental models, and enables translation of results from animal experiments into predictions for human ocular pharmacokinetics (PK).

Major factors affecting intraocular pressure spike after intravitreal ranibizumab injection: Vitreous reflux and its amount

PURPOSE

The aim of this study was to assess the effect of vitreous reflux and its amount on short-term intraocular pressure after intravitreal injection of ranibizumab.

METHODS

The study included 316 eyes of 276 patients. Intraocular pressures were measured before intravitreal injection (preIOP), immediately after intravitreal injection (postIOP0), and 30 min after intravitreal injection (postIOP30). The amount of vitreous reflux was evaluated by measuring conjunctival bleb diameter, and patients were grouped as; group 1: no vitreous reflux, group 2: less vitreous reflux, and group 3: more vitreous reflux. The data were analyzed using variance analysis, chi-square test, and regression analysis.

RESULTS

PostIOP0 values were highest in group 1, followed by group 2 and group 3 (all p values < 0.001). PostIOP30 values were similar in group 1 and group 2 (p = 0.261), but were lower in group 3 than other two groups (p < 0.001, p = 0.001, respectively). Vitreous reflux was identified as the only factor affecting postinjection intraocular pressure changes (p < 0.001), and a negative correlation was found between the total number of intravitreal injection and vitreous reflux (p = 0.032).

CONCLUSION

The major factor affecting short-term postinjection intraocular pressure elevation was vitreous reflux, and intraocular pressure levels increased as the amount of vitreous reflux decreased. Vitreous reflux and its amount decreased as the total number of intravitreal injection increased.

Anterior chamber paracentesis during intravitreal injections in observational trials: effectiveness and safety and effects

A paracentesis prior to an intravitreal injection is a very safe procedure and can prevent IOP-spikes after injections. As these spikes pose the risk of inducing glaucomatous changes particularly in patients with frequent injections and/or with a risk profile, a regular paracentesis prior to an injection may be considered and discussed with the patient.

Hypotensive efficacy of topical brimonidine for intraocular pressure spikes following intravitreal injections of antivascular endothelial growth factor agents: a randomised crossover trial

PURPOSE

To determine the effect of topical brimonidine tartrate prophylaxis on intraocular pressure (IOP) spikes following intravitreal injection of antivascular endothelial growth factor (anti-VEGF) agents.

METHODS

This is a randomised crossover trial of consecutive non-glaucomatous eyes receiving intravitreal anti-VEGF injections between December 2016 and July 2017. All eyes were randomly assigned to no prophylaxis or topical brimonidine tartrate 0.15 % administered 20 min prior to injection in one of two consecutive visits. Measurements of IOP were obtained immediately (T0), 10 min (T10) and 20 min (T20) after injection during the visits with and without prophylaxis.

RESULTS

Among the 58 eyes of 55 patients (116 visits), the mean (SD) age was 74.3 (11.6), and 62% were female. The mean baseline IOP was 15.3 (2.3) mm Hg (range: 11-20). On average, the immediate postinjection IOP during the visit without prophylaxis was 41.6 (12) mm Hg (range: 17-81). Compared with no prophylaxis, the visit with preadministered topical brimonidine tartrate had a lower IOP at T0 (p<0.001), T10 (p=0.001) and T20 (p=0.043), and a smaller proportion of eyes with IOP elevation of greater than 20 mm Hg from preinjection (p=0.002) and IOP greater than 50 mm Hg at T0 (p=0.036). Without prophylaxis, two eyes (two patients) had an IOP of greater than 70 mm Hg at T0 and thus underwent anterior chamber paracentesis.

CONCLUSION

Topical brimonidine tartrate prophylaxis for intravitreal injection of anti-VEGF agents effectively reduces IOP spikes in non-glaucomatous eyes and may be easily incorporated into ophthalmologists' current practice.

TRIAL REGISTRATION NUMBER

NCT03513172.

The Effects of Intravitreal Ranibizumab, Aflibercept or Dexamethasone Implant Injections on Intraocular Pressure Changes

BACKGROUND The aim of this study was to compare the alterations in intraocular pressure (IOP) values during the early postoperative period after intravitreal ranibizumab, aflibercept, or dexamethasone implant injections. MATERIAL AND METHODS In this retrospective study, a total of 188 patients were grouped into 3 groups: the ranibizumab group, the aflibercept group, and the dexamethasone group. Ocular axial length (AXL) and anterior chamber depth (ACD) were measured in the pre-injection period. IOP was measured just before the injection at 1 minute,10 minutes, 1 hour, 1 day, and 1 month after injection. RESULTS There was a transient peak in the ranibizumab group and the aflibercept group at 1 minute that started to decrease at 10 minutes and IOP values returned to preoperative values at approximately 1 hour. Similar alterations were also determined for the dexamethasone group with a lesser increase noted. In the correlation analysis, only alterations in IOP levels at 1 minute were negatively correlated with preoperative AXL values. There was not any correlation between preoperative AXL or ACD values and IOP alterations at any other time points. CONCLUSIONS There was a sudden, transient increase in IOP values after intravitreal ranibizumab or aflibercept injections; which return to normal values in a short time without requirement of any medical treatments. This transient peak was determined to be negatively correlated with the preoperative AXL.

[Structural changes in the ocular anterior segment against elevation of intraocular pressure after repeated intravitreal injections]

Numerous studies have demonstrated the efficacy of anti-VEGF medications for exudative (wet) age-related macular degeneration (AMD). Significant IOP elevation is one of the side effects of anti-VEGF intravitreal injection.

PURPOSE

To study the changes in the parameters of anterior segment of the eyeball against acute IOP elevation after repeated intravitreal injections (IVI) of anti-VEGF medication.

MATERIAL AND METHODS

The study was conducted on a random sample of 45 patients (45 eyes) diagnosed with exudative (wet) form of AMD. All patients received two 0.05 ml intravitreal injections of ranibizumab with one-month interval. Measurements of IOP were performed with rebound tonometer Icare-Pro (ICare, Finland) before intravitreal injection, then one minute, 30 minutes and 3 hours after. The parameters of the ocular anterior segment, namely thickness and optical density of the cornea, volume and angle of the anterior chamber were evaluated by Scheimpflug imaging (Pentacam HR, Oculus, Germany) before IVI, and 15 minutes after.

RESULTS

Statistically significant (p<0.05) elevation of IOP to 40 mm Hg (confidence interval 32-48 mm Hg) was recorded one minute after injecting 0.05 mL of ranibizumab solution into the vitreous cavity with IOP having the tendency for gradual normalization. When measured 15 minutes after IVI, the following parameters of the ocular anterior segment structures had reliably changed in the setting of elevated IOP: corneal thickness had increased to 27 µm (confidence interval 14-38 µm), corneal optical density - to 16.7 (confidence interval 10.4-19.5). No significant changes of either volume or angle of anterior chamber were revealed. Comparative analysis showed no significant changes of parameters after the 1^st and the 2^nd IVI.

CONCLUSION

The revealed changes were transient in nature and did not require any corrections since all parameters returned to baseline after each injection.

[Changes in intraocular pressure after intravitreal injections]

At present, intravitreal drug injections are used for treatment of various diseases of posterior segment of the eye. Among its side effects is significant rise of intraocular pressure (IOP).

PURPOSE

To study the changes in IOP levels after two intravitreal injections.

MATERIAL AND METHODS

The study was performed on a random selection of 335 patients (335 eyes) diagnosed with choroidal neovascular membrane (CNVM). All the patients received intravitreal injections of ranibizumab according to medical indications. IOP was measured by rebound tonometer Icare-Pro (Icare, Finland) before intravitreal injection, as well as 1 minute, 30 minutes and 3 hours post-injection. Injection was repeated one months after the initial procedure.

RESULTS

Intravitreal injection of additional liquid volume causes significant IOP rise, up to 38 mm Hg in average (confidence interval 30-45 mm Hg, p<0.05), with further tendency for IOP to self-normalize. After 30 minutes, IOP remained slightly higher than the initial level - 18 mm Hg (confidence interval 15-21 mm Hg, p<0.05). After 3 hours, IOP approached baseline level - 14 mm Hg (confidence interval 12-16 mm Hg, p<0.05). After the second injection, IOP was observed to decrease slower, causing more patients (28% compared to 21% after the first injection) to have IOP raised by 6 to 10 mm Hg from the initial level 30 minutes after the procedure.

CONCLUSION

The revealed changes can serve as a pathophysiological model for studying changes of biometric parameters of anterior and posterior eye segments and biomechanical properties of fibrous tunic.

Ocular translational science: A review of development steps and paths

Developing successful drug delivery methods is challenging for any tissue, and the eye is no exception. Translating initial concepts into advanced technologies treating diseases in preclinical models and finally into functional and marketable products for humans can be particularly daunting. While referring to specific ophthalmic companies and products, this review considers key exchanges that lead to successful translation. By building on basic science discoveries in the academic setting, applied science can perform proof-of-concept work with simple, benchtop experiments. Eventually, simple models need to be translated to more robust ones where cells, tissues, and entire organisms are incorporated. Successful translation also includes performing due diligence of the intellectual property, understanding the market needs, undertaking clinical development, meeting regulatory requirements, and eventually scale up manufacturing. Different stages of the translation can occur in different environments, including moving from academia to industry, from one company to another, or between veterinary and human applications. The translation process may also rely on contract organizations to move through the complex landscape. While the path to a commercial, marketable product may not look the same each time, it is important to design a development plan with clear goals and milestones to keep on track.

The acute and chronic effects of intravitreal anti-vascular endothelial growth factor injections on intraocular pressure: A review

The acute and chronic effects of repeated intravitreal antivascular endothelial growth factor (VEGF) injections on intraocular pressure have not been fully characterized, and the development of sustained ocular hypertension could adversely affect patients who are at risk of glaucomatous optic neuropathy. As expected, volume-driven, acute ocular hypertension immediately follows intravitreal injection, but this pressure elevation is generally transient and well tolerated. Several medications have been investigated to limit acute ocular hypertension following anti-VEGF therapy, but the benefits of pretreatment are not conclusive. Chronic, sustained ocular hypertension, distinct from the short-term acute ocular hypertension after each injection, has also been associated with repeated intravitreal anti-VEGF injections. Risk factors for chronic ocular hypertension include the total number of injections, a greater frequency of injection, and preexisting glaucoma. Proposed mechanisms for chronic ocular hypertension include microparticle obstruction, toxic or inflammatory effects on trabecular meshwork, as well as alterations in outflow facility by anti-VEGF agents. Although limiting anti-VEGF therapy could minimize the risk of both acute and chronic ocular hypertension, foregoing anti-VEGF therapy risks progression of various macular diseases with resulting permanent central vision loss. While definitive evidence of damage to the retinal nerve fiber layer is lacking, patients receiving repeated injections should be monitored for ocular hypertension and patients in whom sustained ocular hypertension subsequently developed should be periodically monitored for glaucomatous changes with optic nerve optical coherence tomography and static visual fields.

Effect of prophylactic intraocular pressure-lowering medication (brinzolamide) on intraocular pressure after ranibizumab intravitreal injection: A case-control study

Purpose:

To observe the effect of prophylactic intraocular pressure (IOP)-lowering medication (brinzolamide) on IOP after ranibizumab intravitreal injections (IVIs).

Materials and Methods:

This prospective case–control study included 352 eyes from 352 patients (1 eye per patient) who were treated with ranibizumab intravitreal injection and divided randomly into two groups. Two hundred and three patients in control group only received the ranibizumab IVI, but 149 patients in case group received one drop of prophylactic intraocular brinzolamide preinjection. The IOP was measured by noncontact tonometer before injection, at 10, 30, 120 min and 1 day after injection in a sitting position.

Results:

The mean IOP measured before injection, at 10, 30, 120 min and 1 day after injection individually were 15.79 ± 2.21 mmHg, 19.33 ± 4.86 mmHg, 16.64 ± 2.93 mmHg, 16.17 ± 3.13 mmHg, and 15.07 ± 2.55 mmHg in case group and were 15.82 ± 2.57 mmHg, 21.34 ± 5.88 mmHg, 18.17 ± 4.06 mmHg, 17.59 ± 4.42 mmHg, and15.48 ± 2.92 mmHg in control group. Comparing two groups, the mean increase on IOP was statistically significant at 10, 30, 120 min postinjection (P < 0.05).

Conclusions:

IVI of ranibizumab causes a considerable short-term transient rise on IOP in most patients. The effect of prophylactic IOP-lowering medication on IOP after IVIs can be statistically significant from 10 min to 2 h after IVIs.

Intraocular Pressure Changes Following Intravitreal Melphalan and Topotecan for the Treatment of Retinoblastoma With Vitreous Seeding

PURPOSE

To investigate the impact of intravitreal chemotherapy on intraocular pressure (IOP) in children with retinoblastoma.

METHODS

This was a retrospective study of 10 eyes of 10 patients with retinoblastoma (7 males, 3 females, mean age: 33.6 ± 9.4 months) with vitreous seeding injected with intravitreal melphalan and topotecan. IOP was measured with Tonopen (Reichert, Inc., Buffalo, NY) at baseline prior to injecting and then repeatedly following each intravitreal injection.

RESULTS

Mean pre-injection IOP was 8.2 ± 2.3 mm Hg (range: 4 to 12 mm Hg). Mean IOP 1 to 30 seconds after intravitreal melphalan (first injection) was 45.4 ± 14.3 mm Hg. The IOP of 89.5% of patients declined to 29 mm Hg or less in a mean 153.3 ± 97.5 seconds. Mean IOP 1 to 30 seconds after intravitreal topotecan (second injection) was 44.5 ± 11.0 mm Hg, which decreased to 31.0 ± 5.0 mm Hg by 150 seconds after injection. No significant relationship was found between age and post-injection IOP elevation. IOP exceeded the calculated mean arterial perfusion pressure in four encounters.

CONCLUSIONS

Intravitreal chemotherapy caused a transient rise in IOP. Post-injection IOP elevations can reach levels that may exceed mean arterial pressure. [J Pediatr Ophthalmol Strabismus. 2017;54(3):185-190.].

Acute angle closure attack after an intravitreal bevacizumab injection for branch retinal vein occlusion: a case report

Background

Intravitreal injection is widely used to treat retinal vein occlusion, and acute angle closure (AAC) is an exceptional complication of intravitreal injection. The authors report a case of AAC that occurred immediately after administering intravitreal bevacizumab to treat branch retinal vein occlusion (BRVO).

Case presentation

A 65-year-old woman was referred to the retina clinic of a tertiary referral center for the treatment of macular edema secondary to BRVO. On slit lamp examination, anterior chamber (AC) depth was shallow (3 corneal thicknesses centrally, 1/4 corneal thicknesses peripherally) in both eyes. Intraocular pressure (IOP) was 19 mmHg in both eyes, and refractive error was +1.00 diopter sphere in both eyes. A gonioscopy exam demonstrated narrow angle of over 180° in both eyes. To treat the macular edema, bevacizumab was injected into her right eye intravitreally. After two bevacizumab injections, the macular edema regressed but recurred 5 months later, and thus, a third injection was performed. The next day, she visited our emergency department complaining of persistent ocular pain in her right eye. The right pupil had dilated to 6 mm diameter and was fixed. Slit lamp exam revealed diffuse corneal edema in her right eye, which had an IOP of 56 mmHg. After administration of intravenous mannitol, the IOP fell to 14 mmHg and the corneal edema disappeared. Subsequently, a glaucoma specialist performed laser iridotomy on the right eye.

Conclusions

Although AAC is a rare complication of intravitreal injection, it can occur in a patient with risk factors such as hyperopic eye or narrow angle.

Sustained Elevation of Intraocular Pressure Associated with Intravitreal Administration of Anti-vascular Endothelial Growth Factor: A Systematic Review and Meta-Analysis

This study aimed to assess whether repetitive intravitreal injections (IVI) of anti-vascular endothelial growth factor (anti-VEGF) cause sustained elevation of intraocular pressure (SE-IOP). We conducted a systematic review and meta-analysis based on five randomized controlled trials (RCTs) assessing 1428 subjects and 17 non-RCTs evaluating 8358 cases. In the RCTs, an increased risk of SE-IOP was found in the anti-VEGF group (summary risk ratio [RR] = 3.00, 95% confidence interval [CI]: 1.63–5.53) compared with the sham injection or laser group. The increased risk of SE-IOP was correlated with follow-up duration (RR = 2.14, 95% CI 0.69–6.57 at 6 months; RR = 3.15, 95% CI 0.99–10.09 at 12 months; RR = 3.48, 95% CI 1.38–8.78 at 23 months). The risk of SE-IOP after non-exclusion of pre-existing glaucoma patients (RR = 3.48, 95% CI 1.38–8.78) was higher than that obtained after excluding pre-existing glaucoma patients (RR = 2.6, 95% CI 1.16–5.81). In non-RCTs, the pooled prevalence of SE-IOP was 4.7% (95% CI 3.7–5.8) regardless of diagnosis criteria. In conclusion, repeated intravitreal injections of anti-VEGF agents cause a 2-fold elevation in SE-IOP risk.

Intravitreal infusion: A novel approach for intraocular drug delivery

Intraocular injection has become an increasingly important intervention in the treatment of posterior segment diseases. However, an acute intraocular pressure (IOP) elevation after intravitreal injection is a common concern. This study aimed to evaluate the efficacy of intravitreal infusion in maintaining stable IOP in a rabbit model. Trypan blue (TB) 0.06% with an external pump was used to evaluate intravitreal infusion in rabbit eyes. Groups A (50 μL), B (100 μL), C (150 μL), and D (200 μL) were slowly infused over 30 minutes with TB. As a control, Group E underwent conventional intravitreal injection of 100 μL of TB. Group F received a bolus infusion of 100 μL of TB within 1 minute. The mean increases in IOP during infusion for each group were: Group A (7.93 ± 3.80 mmHg), B (13.97 ± 3.17 mmHg), C (19.91 ± 6.06 mmHg) and D (29.38 ± 8.97 mmHg). Immediately post-injection in group E the mean increase in IOP amounted to 34.33 ± 6.57 mmHg. The mean increase in IOP of group F after bolus infusion was 49.89 ± 1.71 mmHg. Intravitreal infusion maintains a stable IOP and provides a controlled infusion speed compared with intravitreal injection.

Ocular Hypertension Following Intravitreal Antivascular Endothelial Growth Factor Therapy: Review of the Literature and Possible Role of Nitric Oxide

PURPOSE

To review the literature regarding ocular hypertension following intravitreal antivascular endothelial growth factor therapy, and to propose a novel mechanism for the development of ocular hypertension as a result of such therapy.

METHODS

The PubMed database was used to identify publications by using combinations of the search terms, "glaucoma," "ocular hypertension," "pegaptanib," "bevacizumab," "ranibizumab," "aflibercept," "anti-vascular endothelial growth factor," intraocular pressure," and "intravitreal." The reference lists of these publications were also reviewed for relevant articles.

RESULTS

Numerous articles have been published describing ocular hypertension, either immediate-term/short-term or delayed/sustained, following intravitreal antivascular endothelial growth factor therapy. Ocular hypertension has been reported following intravitreal pegaptanib, bevacizumab, and ranibizumab, and aflibercept. On the basis of the fact that vascular endothelial growth factor, normally present as a vascular modulating and reparative growth factor, is known to upregulate endothelial nitric oxide (NO) synthase, and that NO has been shown to decrease intraocular pressure in both normal and glaucomatous human and animal eyes, we propose a novel mechanism for sustained ocular hypertension following intravitreal antivascular endothelial growth factor therapy. We propose that such intravitreal therapy may lead to decreased NO in the anterior segment, which then leads to trabecular meshwork constriction, decreased outflow facility, and increased intraocular pressure.

CONCLUSIONS

Sustained ocular hypertension following the intravitreal administration of antivascular endothelial growth factor agents is a potentially serious side effect that has not been adequately explained. Further investigation is necessary to determine the role of NO in the mediation of this adverse effect.

Intraocular Pressure Spikes after Aflibercept Intravitreal Injections

The objective of this study was to assess the intraocular pressure (IOP) as well as the anatomical modifications of the anterior segment following an aflibercept injection. Patients underwent an aflibercept intravitreal injection (IVI) (0.05 ml) with a 30.5-gauge needle and an antireflux system. IOP was assessed before injection (T0), immediately after (T1), and 5 min (T5), 15 min (T15), and 45 min (T45) after the IVI. Before the IVI and immediately after the T1 measurement, a PENTACAM® acquisition was used to evaluate the anterior chamber parameters (anterior chamber volume, depth and measure of the iridocorneal angle). At T0, IOP was 12.9 ± 1.3 mm Hg. IOP significantly increased after IVI (42.7 ± 3 mm Hg, p < 0.001). IOP returned to baseline at T45 (13.0 ± 1.2 mm Hg, p = 0.877). Anterior chamber volume decreased after IVI (160.6 vs. 168.3 mm3, p = 0.002). No significant changes were found for iridocorneal angle and anterior chamber depth. Aflibercept IVI causes an acute increase in IOP over a short period without iridocorneal angle closure.

[Intravitreal injection as a possible model for studying biomechanics of fibrous tunic]

The article summarized the results of Russian and foreign research concerning biomechnical principles of eye functioning as an integral physiological system. Quite a number of studies have been published on corneal and scleral mechanics, which is also part of the said system. These studies fall largely into three groups: in vivo studies (involving living organism), in vitro studies (within an artificial environment), and mathematical modeling. In vivo techniques are often rather complicated and, therefore, most studies are based on in vitro procedures. Due to the growing number of intravitreal injections, they can be regarded as a stress test for studying fibrous tunic biomechanics in vivo. The results of such studies would contribute to a better understanding of the pathogenesis of various eye diseases and thus, a better clinical practice.

Effect of dorzolamide-timolol fixed combination prophylaxis on intraocular pressure spikes after intravitreal bevacizumab injection

AIM

To evaluate the effect of topical dorzolamide-timolol fixed combination prophylaxis on short term intraocular pressure (IOP) changes in patients who had intravitreal bevacizumab injection.

METHODS

One hundred and fifty one eyes of 151 patients which were followed up in retina clinic in Ulucanlar Eye Training and Research Hospital were evaluated in this study. Patients were divided into two groups. Group 1 consists of 75 patients who had topical dorzolamid-timolol medication two hours before injection; while Group 2 consists of 76 patients without prophylaxis. Demographic data, IOP measurements prior to the injection and one, thirty and sixty minutes and twenty-four hours after the injection were recorded. The data were analyzed using SPSS software version 15.0 (SPSS Inc., Chicago, IL, USA).

RESULTS

There were no significant difference between two groups in age, gender distrubition and indications for injections. The mean IOPs in Groups 1 and 2 prior to the injection (T0) were 17.84±0.43 and 18.15±0.43 mm Hg, one minute after the injection (T1) were 29.75±1.6 and 34.44±1.59 mm Hg, 30min after the injection (T30) were 20.06±0.6 and 21.71±0.59 mm Hg respectively. The mean IOPs were 18.26±0.56 mm Hg in Group 1 and 19.78±0.56 mm Hg in Group 2 sixty minutes after the injection (T60). All IOP values after the injection were compared between two groups, there was a significant difference between two groups only on T1; one minute after the injection (P=0.04). There were a statiscially significant difference between the baseline values and other recorded values; except on T60, in Groups 1 and 2 (P<0.05).

CONCLUSION

After intravitreal bevacizumab injection; we observe a transient IOP elevation which normalizes about one hour after intravitreal injection. In patients who had topical dorzolamid-timolol combination prophylaxis before injections, a significant decrease is seen in IOP spikes due to this injection. The appropiate approach will monitor IOP after intravitreal injection and evaluate the using prophylactic antiglaucomatous drugs before the injection in patients with ganglion nerve cell damage.

Does intravitreal injections of bevacizumab for age-related macular degeneration affect long-term intraocular pressure?

PURPOSE

To evaluate the long-term intraocular pressure (IOP) changes after intravitreal injection of bevacizumab for age-related macular degeneration.

PATIENTS AND METHODS

A total of 83 eyes that received intravitreal injections of bevacizumab for age-related macular degeneration were enrolled. IOP measurements at baseline, 6, 12, 18, and 24 months, and at the last follow-up after injection were analyzed. On the basis of the median number of injections, the changes in IOP were compared.

RESULTS

The mean number of injections was 3.71±1.62. There was no significantly higher elevation than baseline IOP (14.11±2.76 mm Hg) after multiple intravitreal injections of bevacizumab (P>0.05). In the group which had ≥4 injections, mean IOP measurements were not higher compared with the group which had <4 injections during the follow-up period (P>0.05). In the patients with preexisting glaucoma (3 eyes), there were no significant increases of IOP during the follow-up period.

CONCLUSIONS

IOP elevation was not observed during the long-term follow-up period. In addition, the numbers of injection and preexisting glaucoma did not affect IOP changes.

Short-term intraocular pressure trends following intravitreal ranibizumab injections for neovascular age-related macular degeneration-the role of oral acetazolamide in protecting glaucoma patients

PURPOSE

To determine the effect of oral acetazolamide on lowering the peak and duration of intraocular pressure (IOP) rise in glaucoma and glaucoma suspect patients, following intravitreal injection of ranibizumab for neovascular age-related macular degeneration.

METHODS

The study was an open-label, parallel, randomised, controlled trial (EudraCT Number: 2010-023037-35). Twenty-four glaucoma or glaucoma suspect patients received either 500 mg acetazolamide or no treatment 60-90 min before 0.5 mg ranibizumab. The primary outcome measure was the difference in IOP immediately after injection (T0) and 5, 10, and 30 min following injection. ANCOVA was used to compare groups, adjusting for baseline IOP. The study was powered to detect a 9-mm Hg difference at T0.

RESULTS

The IOP at T0 was 2.3 mm Hg higher in the non-treated group (mean 44.5 mm Hg, range (19-86 mm Hg)) compared with the treated group (mean 42.2 mm Hg, range (25-58 mm Hg)), but was not statistically significant after adjusting for baseline IOP (P=0.440). At 30 min, IOP was 4.9 mm Hg higher in the non-treated group (mean 20.6 mm Hg, range (11-46 mm Hg)) compared with the treated group (mean 15.7 mm Hg, range (8-21 mm Hg)). This was statistically significant after adjusting for baseline IOP (P=0.013).

CONCLUSIONS

Although the primary end points were not reached, 500 mg oral acetazolamide, 60-90 min before intravitreal injection, results in a statistically significant reduction in IOP at 3O min post injection. Prophylactic treatment may be considered as an option to minimise neuro-retinal rim damage in high-risk glaucoma patients who are most vulnerable to IOP spikes and undergoing repeated intravitreal injections of ranibizumab.

Estimation of ocular volume from axial length

BACKGROUND/AIMS

To determine which biometric parameters provide optimum predictive power for ocular volume.

METHODS

Sixty-seven adult subjects were scanned with a Siemens 3-T MRI scanner. Mean spherical error (MSE) (D) was measured with a Shin-Nippon autorefractor and a Zeiss IOLMaster used to measure (mm) axial length (AL), anterior chamber depth (ACD) and corneal radius (CR). Total ocular volume (TOV) was calculated from T2-weighted MRIs (voxel size 1.0 mm(3)) using an automatic voxel counting and shading algorithm. Each MR slice was subsequently edited manually in the axial, sagittal and coronal plane, the latter enabling location of the posterior pole of the crystalline lens and partitioning of TOV into anterior (AV) and posterior volume (PV) regions.

RESULTS

Mean values (±SD) for MSE (D), AL (mm), ACD (mm) and CR (mm) were -2.62±3.83, 24.51±1.47, 3.55±0.34 and 7.75±0.28, respectively. Mean values (±SD) for TOV, AV and PV (mm(3)) were 8168.21±1141.86, 1099.40±139.24 and 7068.82±1134.05, respectively. TOV showed significant correlation with MSE, AL, PV (all p<0.001), CR (p=0.043) and ACD (p=0.024). Bar CR, the correlations were shown to be wholly attributable to variation in PV. Multiple linear regression indicated that the combination of AL and CR provided optimum R(2) values of 79.4% for TOV.

CONCLUSION

Clinically useful estimations of ocular volume can be obtained from measurement of AL and CR.

The link between intravitreal antivascular endothelial growth factor injections and glaucoma

PURPOSE OF REVIEW

To summarize the reports of both transient and sustained elevation in intraocular pressure (IOP) associated with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) agents and to review the possible mechanisms for these findings.

RECENT FINDINGS

Transient elevation in IOP is common after intravitreal injection of anti-VEGF agents. Sustained IOP elevation is less commonly seen but can require medical and/or surgical intervention. The mechanism for sustained IOP elevation is not well understood but has been attributed to trabecular meshwork injury from repeated injections, a potential toxic or inflammatory reaction after exposure to the biologic agents and/or vehicle, or mechanical blockade of the trabecular meshwork by protein aggregates or contaminant particles associated with packaging and injection techniques, among other potential causes.

SUMMARY

Intravitreal anti-VEGF injections are commonly used to treat neovascular diseases of the eye. Although they have a favorable side-effect profile, their use can be associated with both transient and sustained elevation in IOP. Further research is necessary to determine the cause of these findings.