Managing normal tension glaucoma by lowering the intraocular pressure

Rapid Retinal Nerve Fiber Layer Thinning in the Unaffected Contralateral Eyes of Patients with Unilateral Normal-Tension Glaucoma: A Retrospective Observational Study

PURPOSE

To observe the rate of progressive retinal nerve fiber layer (RNFL) thinning in the unaffected eyes of patients with unilateral normal-tension glaucoma (NTG), in comparison with that of healthy subjects, and to identify the factors associated with progressive RNFL thinning.

DESIGN

Retrospective, longitudinal, observational study.

PARTICIPANTS

Ninety-five patients with unilateral NTG and 61 healthy controls.

METHODS

This study included unilateral NTG and healthy control subjects who were followed up for longer than 4 years and in whom at least 5 reliable retinal nerve fiber layer thickness (RNFLT) measurements were performed using OCT. Factors associated with the rate of thinning of the unaffected eyes of unilateral patients with NTG were identified using regression analysis.

MAIN OUTCOME MEASURES

The rate of progressive RNFL thinning and the associated factors.

RESULTS

Retinal nerve fiber layer thickness decreased significantly in both the unaffected eyes of unilateral patients with NTG and the healthy eyes (both P < 0.001). The RNFL thinning was significantly faster in the unaffected eyes of unilateral patients with NTG than in the healthy eyes (P < 0.001), specifically in the temporal-inferior (TI) sector (P = 0.003). Factors associated with faster RNFL thinning in the unaffected eyes of unilateral patients with NTG were thicker baseline RNFL of the unaffected eyes (P = 0.002) and a worse visual field (VF) mean deviation (MD) in the NTG eyes (P = 0.040). In the healthy controls, the rate of RNFL thinning in the contralateral eyes was the only factor associated with faster thinning (P = 0.007).

CONCLUSIONS

The unaffected eyes of unilateral patients with NTG showed faster RNFL thinning than healthy control eyes, more obviously in the TI sector, and were likely to progress faster when they had a thicker baseline RNFL, and when the NTG eyes had a worse VF MD. In unilateral patients with NTG, initiation of prophylactic treatment could be considered for the unaffected eyes when they are accompanied by a risk of developing glaucoma.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Effect of Intravenous Mannitol on Intraocular Pressure Changes in Vitrectomized and Non-Vitrectomized Eyes: A Systematic Review and Meta-Analysis

PURPOSE

Intraocular pressure (IOP) control is paramount during ophthalmic surgeries to ensure successful outcomes and prevent complications. Intravenous mannitol has been explored for its ability to manage IOP fluctuations in both vitrectomized and non-vitrectomized eyes. This meta-analysis aimed to assess the efficacy of mannitol in controlling IOP across these patient groups.

DESIGN

Systematic review and meta-analysis.

METHODS

A literature search was conducted across PubMed, EMBASE, Scopus, and Web of Science from inception up to March 1, 2024, focusing on studies investigating mannitol's impact on IOP in vitrectomized and non-vitrectomized eyes. Randomized controlled trials, cohort studies, and case-control studies were included, while case reports and review articles were excluded. The primary outcome was the change in IOP following mannitol administration. Meta-analysis was performed using a random-effects model. R software (V 4.3) was used for statistical analysis.

RESULTS

Our search included five studies of both vitrectomized (145 eyes) and non-vitrectomized eyes (91 eyes). The meta-analysis demonstrated significant IOP reductions following mannitol administration across multiple time points. Three studies were included at 30 min and 2 studies at all other time points in the analysis. In vitrectomized eyes, notable decreases were observed: at 30 min, the Ratio of Means (ROM) was 0.81 (95% CI: 0.53; 1.24), indicating a 19% reduction; at 60 min, the ROM of 0.833 (95% CI: 0.77; 0.89) showed a 16.7% reduction; at 90 min, the ROM of 0.757 (95% CI: 0.755; 0.758) corresponded to a 24.3% reduction; at 2 h, the ROM of 0.726 (95% CI: 0.642; 0.820) reflected a 27.4% reduction; at 3 h, the ROM of 0.692 (95% CI: 0.600; 0.797) resulted in a 30.8% reduction; and at 4 h, the ROM of 0.700 (95% CI: 0.363; 1.350) indicated a 30% reduction. No significant changes were observed on IOP with mannitol administration when comparing vitrectomized versus non- vitrectomized eyes.

CONCLUSION

Intravenous mannitol effectively reduces IOP in both vitrectomized and non-vitrectomized eyes, demonstrating its utility in the acute management of elevated IOP during and after ophthalmic surgeries. These findings support the integration of mannitol into perioperative care protocols. However, further research, particularly randomized controlled trials and studies with broader demographic representation, is needed to optimize mannitol's usage and fully understand its long-term safety and efficacy.

Long-Term Surgical Outcomes of Glaucoma Drainage Implants in Eyes with Preoperative Intraocular Pressure Less than 19 mmHg

Background

This retrospective review reports on patients who underwent glaucoma drainage implant (GDI) surgery and had baseline intraocular pressure (IOP) of ≤18 mmHg with at least one year of follow-up.

Methods

Clinical data of 67 eyes of 67 patients were collected from patients' charts, and the outcomes of GDI were evaluated until 7 years. GDI failure was defined as IOP reduction of less than 20% from the baseline at two consecutive visits three months after surgery, decline to no light perception, or if additional glaucoma surgery was performed.

Results

The average age was 65.9 ± 13.2 years. Most cases were male (52.2%), White (53.7%), and had primary open-angle glaucoma (62.7%). Forty-four eyes had prior glaucoma surgery (68.6%) and 46 (68.6%) had severe glaucoma. Though postoperative (postop) IOP changes were insignificant, the average postop number of medications dropped from 2.4 ± 1.4 to 1.9 ± 1.2 medications two years after surgery (p = 0.0451). Postop complications (23.9%) included GDI exposure (7.5%), inflammation (4.5%), shallow anterior chamber (4.5%), and strabismus (1.5%). Hypotony was observed in 4 eyes (5.9%), none of which developed hypotony maculopathy. The cumulative one-year failure rate was 56.7%, most of which were due to failure to lower IOP.

Conclusion

In patients with baseline IOP ≤18 mmHg who had GDI surgery, though the change in IOP was not statistically significant, the number of medications dropped and visual field progression slowed in a subset of patients with adequate perimetric data. Due to a relatively high rate of complications and limited effectiveness in lowering IOP, GDI should be cautiously used in these eyes.

Melatonin prevents EAAC1 deletion-induced retinal ganglion cell degeneration by inhibiting apoptosis and senescence

Normal tension glaucoma (NTG) is referred to as a progressive degenerative disorder of the retinal ganglion cells (RGCs), resulting in nonreversible visual defects, despite intraocular pressure levels within the statistically normal range. Current therapeutic strategies for NTG yield limited benefits. Excitatory amino acid carrier 1 (EAAC1) knockout (EAAC1-/- ) in mice has been shown to induce RGC degeneration without elevating intraocular pressure, mimicking pathological characteristics of NTG. In this study, we explored whether daily oral administration of melatonin could block RGCs loss and prevent retinal morphology and function defects associated with EAAC1 deletion. We also explored the molecular mechanisms underlying EAAC1 deletion-induced RGC degeneration and the neuroprotective effects of melatonin. Our RNA sequencing and in vivo data indicated EAAC1 deletion caused elevated oxidative stress, activation of apoptosis and cellular senescence pathways, and neuroinflammation in RGCs. However, melatonin administration efficiently prevented these detrimental effects. Furthermore, we investigated the potential role of apoptosis- and senescence-related redox-sensitive factors in EAAC1 deletion-induced RGCs degeneration and the neuroprotective effects of melatonin administration. We observed remarkable upregulation of p53, whereas NRF2 and Sirt1 expression were significantly decreased in EAAC1-/- mice, which were prevented by melatonin treatment, suggesting that melatonin exerted its neuroprotective effects possibly through modulating NRF2/p53/Sirt1 redox-sensitive signaling pathways. Overall, our study provided a solid foundation for the application of melatonin in the management of NTG.

Pharmaceutical Approaches to Normal Tension Glaucoma

Normal tension glaucoma (NTG) is defined as a subtype of primary open-angle glaucoma (POAG) in which the intraocular pressure (IOP) values are constantly within the statistically normal range without treatment and represents approximately the 30-40% of all glaucomatous cases. The pathophysiology of this condition is multifactorial and is still not completely well known. Several theories have been proposed to explain the onset and progression of this disease, which can be divided into IOP-dependent and IOP-independent factors, suggesting different therapeutic strategies. The current literature strongly supports the fundamental role of IOP in NTG. The gold standard treatment for NTG tends to be based on the lowering IOP even if "statistically normal". Numerous studies have shown, however, that the IOP reduction alone is not enough to slow down or stop the disease progression in all cases, suggesting that other IOP-independent risk factors may contribute to the NTG pathogenesis. In addition to IOP-lowering strategies, several different therapeutic approaches for NTG have been proposed, based on vaso-active, antioxidant, anti-inflammatory and/or neuroprotective substances. To date, unfortunately, there are no standardized or proven treatment alternatives for NTG when compared to traditional IOP reduction treatment regimes. The efficacy of the IOP-independent strategies in decreasing the risk or treating NTG still remains inconclusive. The aim of this review is to highlight strategies reported in the current literature to treat NTG. The paper also describes the challenges in finding appropriate and pertinent treatments for this potentially vision-threatening disease. Further comprehension of NTG pathophysiology can help clinicians determine when to use IOP-lowering treatments alone and when to consider additional or alternatively individualized therapies focused on particular risk factors, on a case-by-case basis.

Effectiveness of Trabeculectomy and Tube Shunt with versus without Concurrent Phacoemulsification: Intelligent Research in Sight Registry Longitudinal Analysis

OBJECTIVE

To determine the effectiveness of trabeculectomy and glaucoma drainage device (GDD) surgery performed with concurrent phacoemulsification compared with stand-alone procedures.

DESIGN

Multicenter retrospective cohort study.

PARTICIPANTS

Patients in the Intelligent Research in Sight Registry who underwent trabeculectomy or GDD from 2013 through 2019.

METHODS

The Kaplan-Meier survival analysis was used to determine reoperation rates. Reoperation was defined as any subsequent glaucoma surgery occurring 1 month to 3 years after the initial procedure. Multivariable Cox proportional hazard models were used to determine reoperation risk factors.

MAIN OUTCOME MEASURES

Reoperation rate, intraocular pressure (IOP), visual acuity, reoperation procedure type, postoperative complications, and predictors of surgical failure.

RESULTS

A total of 117 697 eyes undergoing glaucoma surgery alone and 35 657 eyes undergoing surgery with phacoemulsification were included. The cumulative reoperation rates at postoperative years 1 and 3 were 4.9% and 11.5%, respectively, for trabeculectomy alone and 3.0% and 7.3%, respectively, for trabeculectomy combined with phacoemulsification (P < 0.001). The reoperation rates at postoperative 1 and 3 years were 3.8% and 7.8%, respectively, for GDD alone and 2.1% and 5.4%, respectively, for GDD with phacoemulsification (P < 0.001). Stand-alone procedures achieved greater IOP reduction by percentage change from baseline (trabeculectomy alone, 35.3% vs. trabeculectomy with phacoemulsification, 23.1%, P < 0.001; and GDD alone, 36.0% vs. GDD with phacoemulsification, 29.3%; P < 0.001). Visual acuity improved by 0.12 logarithm of the minimum angle of resolution (logMAR) (95% confidence interval [CI], 0.11-0.12) and 0.10 logMAR (95% CI, 0.08-0.11) after trabeculectomy and GDD with phacoemulsification and declined by 0.15 logMAR (95% CI, 0.14-0.15) and 0.12 logMAR (95% CI, 0.11-0.12) after stand-alone trabeculectomy and GDD. The overall documented complication rate was 2.9% for GDD and 1.4% for trabeculectomy. Age, sex, race, ethnicity, baseline IOP, and glaucoma diagnosis and severity were associated with surgical failure risk. The most common reoperation procedure was GDD.

CONCLUSIONS

Reoperation rates within the first 3 years after trabeculectomy and GDD with and without phacoemulsification were low. Trabeculectomy and GDD with phacoemulsification had lower reoperation rates than those with stand-alone procedures. However, stand-alone procedures resulted in greater IOP reduction compared with combined procedures. Postoperative complications were uncommon overall. Patient age, sex, race, ethnicity, baseline IOP, and glaucoma diagnosis and severity were associated with surgical success.

Thinner Central Corneal Thickness is Associated with a Decreased Parapapillary Vessel Density in Normal Tension Glaucoma

This retrospective cross-sectional study, which enrolled 124 normal tension glaucoma (NTG) eyes and 68 healthy eyes as the control, determined the association between central corneal thickness (CCT) and ocular parameters in NTG. CCT was measured using the Pentacam® system, optical coherence tomography angiography (OCT-A) was adopted to measure the peripapillary and macular area VDs, and spatial data were based on the Garway–Heath map as illustrated in OCT-A. Univariate and multivariate linear regressions were used to statistically analyze for associations between CCT and other factors. In this study, the mean age was similar for both the NTG and control groups. The mean CCT of the NTG group was significantly thinner than that of the control group (533.97 ± 33.11 µm vs. 546.78 ± 38.21 µm; $p$  = .022). Considering all the factors, CCT negatively correlated with visual field (VF) pattern standard deviation (univariate, $p$  = .045). To analyze structural and functional factors separately, we found a significant positive correlation between CCT and whole disc radial peripapillary capillary VD (VDRPC; multivariate, $p$  = .019). To analyze the relationship between all factors and sectoral changes in VDRPC, a significant positive correlation was observed between CCT and inferior temporal VDRPC (univariate, $p$  = .039) and inferior nasal VDRPC (VDRPC IN; univariate, $p$  = .048). In conclusion, this novel study shows that among NTG participants, a thinner cornea correlated with weaker biomechanical properties susceptible to optic nerve tissue displacement, especially in response to mild transient elevation of IOP, leads to compromised ocular microcirculation.

Topical Medication Therapy for Glaucoma and Ocular Hypertension

Glaucoma is one of the most common causes of blindness, thus seriously affecting people’s health and quality of life. The topical medical therapy is as the first line treatment in the management of glaucoma since it is inexpensive, convenient, effective, and safe. This review summarizes and compares extensive clinical trials on the topical medications for the treatment of glaucoma, including topical monotherapy agents, topical fixed-combination agents, topical non-fixed combination agents, and their composition, mechanism of action, efficacy, and adverse effects, which will provide reference for optimal choice of clinical medication. Fixed-combination therapeutics offer greater efficacy, reliable security, clinical compliance, and tolerance than non-fixed combination agents and monotherapy agents, which will become a prefer option for the treatment of glaucoma. Meanwhile, we also discuss new trends in the field of new fixed combinations of medications, which may better control IOP and treat glaucoma.

Factors associated with achieving intraocular pressure lower than 15 mmHg by Trabectome surgery in primary open-angle glaucoma

To assess good prognostic factors of Trabectome surgery in primary open-angle glaucoma (POAG), clinical records of patients with POAG who underwent Trabectome surgery with/without cataract surgery as the first additive therapy to eye drops between January 2015 and March 2018 were retrospectively reviewed. Overall, data of 79 eyes (79 patients; 50 men; mean age, 68.0 years) up to postoperative 24 months were analyzed. Their mean intraocular pressure (IOP) was 20.4 ± 6.0 mmHg at baseline. Forty-two eyes (53.2%) achieved an IOP < 15 mmHg and ≥ 20% reduction from baseline without additional treatments. Phakic eyes had a better survival probability than pseudophakic eyes after adjusting for age, sex, baseline IOP, best-corrected visual acuity, and eye drop score (hazard ratio 3.096; 95% confidence interval [95% CI] 1.367–7.013; P = 0.007). Phakic eyes treated with combined Trabectome and cataract surgeries (mean survival time, 22.250 months; 95% CI 17.606–26.894) had a better survival probability than pseudophakic eyes treated with Trabectome surgery only (mean survival time, 12.111 months; 95% CI 8.716–15.506; P = 0.009) after the adjustment. Among the eyes treated with Trabectome surgery only, phakic eyes required significantly less additional treatments than pseudophakic eyes (P = 0.04). Trabectome surgery may be indicated for phakic eyes with POAG in addition to eye-drop therapy.

Long-Term Effectiveness and Safety of Tafluprost, Travoprost, and Latanoprost in Korean Patients with Primary Open-Angle Glaucoma or Normal-Tension Glaucoma: A Multicenter Retrospective Cohort Study (LOTUS Study)

This multicenter retrospective cohort study compared the effectiveness and safety of long-term tafluprost, travoprost, or latanoprost in patients with primary open-angle glaucoma (POAG) or normal-tension glaucoma (NTG). Data were extracted from electronic medical records of 300 patients treated with tafluprost, travoprost, or latanoprost for >6 months. Propensity matching for age and sex was used for effectiveness and safety comparisons. The primary endpoint was visual field (VF) progression via mean deviation (MD) slope. Secondary endpoints were change of MD, intraocular pressure, pattern standard deviation, VF index, and advanced glaucoma intervention study score. Treatment-related adverse events (AEs) were also compared between groups. Overall, 216 POAG or NTG patients were matched into Match Set 1 (72 patients/group), and 177 NTG-only patients in Match Set 2 (59 patients/group) according to: age (mean: 61, 62 years) and sex (male: 53, 56%). There were no statistically significant between-group differences regarding MD slope (p = 0.413, p = 0.374 in Match Sets 1 and 2, respectively). There were no significant between-group differences/tendencies regarding secondary endpoints. No AEs were serious, and there were no significant between-group differences regarding reported AEs. In patients with POAG or NTG, long-term tafluprost, travoprost, or latanoprost showed similar effects. All three prostaglandin analogs had good long-term safety profiles.

Using 24-hr ocular dimensional profile recorded with a sensing contact lens to identify primary open-angle glaucoma patients with intraocular pressure constantly below the diagnostic threshold

PURPOSE

To evaluate the use of a 24-hr ocular dimensional profile recorded with a contact lens sensor (CLS) combined with a single tonometric intraocular pressure (IOP) reading to indicate the potential for exceeding the diagnostic threshold for normal tension glaucoma (NTG) in Japanese patients.

METHODS

Intraocular pressure (IOP) of untreated Japanese NTG patients was measured with tonometry every 3 hr from 9:00 to 24:00. The subsequent day a 24-hr CLS (SENSIMED Triggerfish, Sensimed AG, Lausanne, Switzerland) profile was recorded on the same eye. Patients initially diagnosed as NTG were reclassified as NTG when the measured IOP values were consistently <20 mmHg or as primary open-angle glaucoma (POAG) when IOP was ≥20 mmHg in at least 1 measurement. For each patient and each IOP time-point, IOP values were combined with information provided by the CLS profile ('classifier') to indicate the potential for exceeding the diagnostic threshold value. Statistical analyses were performed for each classifier.

RESULTS

A total of 65 patients, 28 males and 37 females (mean ages: 50.8 ± 14.6 years and 52.6 ± 10.2 years, respectively), were analysed. Following IOP diurnal measurement, five patients (7.7%) were reclassified as POAG. Two classifiers (15:00 CLS and 18:00 CLS) showed high sensitivity and negative predictive value (100%), identifying all the POAG patients.

CONCLUSION

Contact lens sensor information can be used in conjunction with a single tonometric reading to determine patients' potential of having IOP levels exceeding the diagnostic threshold within a 24-hr period, without the need to perform a 24-hr tonometric curve. This would allow clinicians to identify POAG patients who may otherwise be eventually misclassified as NTG.

Proniosomal gel-derived niosomes: an approach to sustain and improve the ocular delivery of brimonidine tartrate; formulation, in-vitro characterization, and in-vivo pharmacodynamic study

Brimonidine tartrate (BRT) is a hydrophilic α2 adrenergic agonist used for the treatment of glaucoma. Glaucoma is an ocular disease affecting the anterior segment of the eye requiring lifetime treatment. Owing to the obstacles facing ocular delivery systems and hydrophilicity of BRT, frequent administration of the eye drops is required. Niosomes have been widely used to improve the ocular bioavailability of the topically applied drugs and to enhance the ocular residence time. However, they have drawbacks as physical instability, aggregation, and loss of the entrapped drug. For this reason, BRT proniosomes were prepared to overcome niosomal instability issues. A D-optimal design was utilized to determine the optimum conditions for preparation of the proniosomal gels. Independent variables were amount of surfactant, surfactant:cholesterol ratio, and type of surfactant used. The dependent variables were entrapment efficiency (EE%), particle size, percentage of drug released after 2 h (Q2h), and percentage of drug released after 24 h (Q24h). The optimum formula was suggested with desirability 0.732 and the composition of 540 mg Span 60 and 10:1 surfactant:cholesterol ratio. The results obtained after reconstitution were; EE% of 79.23 ± 1.12% particle size of 810.95 ± 16.758 nm, polydispersity index (PDI) 0.6785 ± 0.213, zeta potential 59.1 ± 0.99 mV, Q2h40.98 ± 1.29%, Q8h 63.35 ± 6.07%, and Q24h = 91.11 ± 1.76%. Transmission electron microscope imaging of the formula showed the typical spherical shape of niosomes. In-vivo pharmacodynamic study assured the improved ocular bioavailability of BRT selected formula when compared with Alphagan®P with relative AUC0-24 of 5.024 and 7.90 folds increase in the mean residence time (MRT). Lack of ocular irritation of the formula was assured by Draize test.

Effects of intubation with a double-lumen endotracheal tube on intraocular pressure during rapid sequence induction using succinylcholine chloride in patients with or without underlying systemic hypertension

Background

Tracheal intubation is closely associated with increases in intraocular pressure (IOP); however, the effects of double-lumen tube (DLT) intubation on IOP have not been validated. Systemic hypertension (HTN) is another factor that may increase IOP. In this study, we observed differences in IOP increases between DLT and singlelumen tube (SLT) intubation, and evaluated the influence of underlying HTN during rapid sequence induction.

Methods

Sixty-eight patients were allocated into one of the following group: SLT/without HTN (n = 17), SLT/HTN (n = 17), DLT/without HTN (n = 17), and DLT/HTN (n = 17). An SLT was inserted for orthopedic or gynecological surgery, and a DLT was inserted for lung surgery after rapid sequence induction using succinylcholine. IOP was measured before anesthetic induction and until 10 min after intubation using a handheld tonometer (Tono-Pen AVIA^®).

Results

In the DLT/without HTN and DLT/HTN groups, the maximum increases in IOPs after tracheal intubation were 7.9 and 12.2 mmHg, respectively, compared to baseline. In the SLT/without HTN and SLT/HTN groups, the maximum increases were 5.0 and 4.9 mmHg, respectively, compared to baseline. In comparisons between patients with and without underlying HTN, the values of IOPs were comparable.

Conclusions

Tracheal intubation with a DLT is associated with more increases in IOPs than with an SLT in rapid sequence induction. Well-controlled underlying hypertension did not increase IOP during tracheal intubation.

Macular vessel density in untreated normal tension glaucoma with a hemifield defect

PURPOSE

To investigate macular vessel density (MVD) and structural alterations in untreated normal tension glaucoma (NTG) with a hemifield defect (HFD) and to compare these with the findings in healthy eyes.

STUDY DESIGN

Case series with a healthy group for comparison.

METHODS

Thirty-four eyes of 34 untreated NTG patients with HFD and 28 eyes of 28 healthy subjects were enrolled. RTVue-XR Avanti^TM (Optovue, Inc.), a combined OCT-A and SD-OCT system, was used to determine MVD and inner macular thickness (IMT) measurements. Mean circumpapillary retinal nerve fiber (cpRNFL) and macular ganglion cell complex (mGCC) thicknesses were measured with the RTVue-100^TM (Optovue, Inc.). Wilcoxon signed-rank test was used to evaluate differences between defective and normal hemifields in NTG eyes and Mann-Whitney U test to evaluate differences between normal hemifields in NTG eyes and healthy eyes.

RESULTS

In comparison with healthy eyes, the normal hemifields of NTG eyes showed significantly reduced MVD, as well as cpRNFL and mGCC thicknesses, although IMT did not differ between the two groups. The defective hemifield in NTG eyes showed significantly reduced IMT, as well as cpRNFL and mGCC thicknesses, compared with the normal hemifield, although MVD did not differ between the two hemifields.

CONCLUSION

Hemodynamic deficiencies and structural damage might have already begun in the perimetrically normal hemifields of NTG eyes. Further studies are needed to elucidate whether the reduction in MVD may precede structural changes or the reduction in vasculature and structural loss may vary with disease severity in at least in some cases.