Measurement of the retinal venous pressure with a new instrument in patients with primary open angle glaucoma

PURPOSE

To compare the results of retinal venous pressure (RVP) measurement performed with contact lens dynamometry (CLD) and with the new IOPstim.

METHODS

In this cross-sectional study, we included 36 patients with primary open angle glaucoma with a median age (Q25; Q75) of 74 (64; 77) years (m/f = 18/18), baseline intraocular pressure (IOP): 13.9 (12.2; 15.1) mmHg. Median mean defect: - 5.8 (- 11.9; - 2.6) db. Principle of the IOPstim: an empty balloon with a diameter of 8 mm is positioned on the eye, laterally of the limbus. Under observation of the central retinal vein (CRV), the examiner inflates the balloon. As soon as the CRV starts pulsation, the inflation is stopped and the IOP is measured, equaling the RVP at this moment. In the CLD, the pulsation of the CRV is observed with a contact lens. The RVP is calculated from the attachment force applied when pulsation appears.

COURSE OF EXAMINATIONS

Three single measurements of RVP in quick succession with both methods. The sequence of the two methods was randomized. The means of the three RVP measurements were compared.

RESULTS

Pressures in mmHg. RVP: IOPstim: 19.4 ± 5.4 (mean ± SD), CLD: 20.3 ± 5.9. Range of three single measurements: IOPstim: 2.9 ± 1.5, CLD: 2.2 ± 1.1. The differences were RVPIOPstim - RVPCLD =  - 0.94 ± 1.15, and approximately normally distributed. Bland-Altman analysis: only one data point was 0.5 mmHg higher than the upper line of agreement. The confidence interval of this line was 0.65 mmHg. Concordance correlation coefficient according to Lin (CCC): 0.96. Intraclass correlation coefficient: both methods, 0.94.

CONCLUSION

In both methods, the range of the single measurements may be taken as a sign of good reliability, the CCC of 0.96 as a sign of a very good agreement. At the mean, the IOPstim RVP values were 1 mmHg lower than those obtained with the CLD. This difference may be due to the different directions of the prevailing force vectors induced by the instruments. The IOPstim seems applicable in glaucoma diagnostics.

The retinal venous pressure at different levels of airway pressure measured with a new method

PURPOSE

This study is to investigate the increase in retinal venous pressure (RVP) induced by a stepwise increase in airway pressure (AirP) using the new IOPstim method, which is designed to artificially increase the intraocular pressure (IOP) and thus to stimulate vascular pulsation.

METHODS

Twenty-eight healthy subjects were examined in the left eye. The RVP was measured at baseline and at four different levels of AirP (10, 20, 30, and 40 mmHg) using the new IOPstim method: a half balloon of 8 mm diameter is inflated laterally to the cornea under observation of the central retinal vein. As soon as the vein pulsates at a certain AirP level, the IOP is measured with a commercially available tonometer, which then corresponds to the RVP.

RESULTS

Spontaneous venous pulsation was observed in all study participants. The mean RVP values at baseline and at the AirP levels of 10, 20, 30, and 40 mmHg were 17.6 ± 2.8 mmHg; 20.1 ± 3.0 mmHg; 22.1 ± 3.5 mmHg; 24.3 ± 3.7 mmHg, and 26.6 ± 4.2 mmHg, respectively. The mean RVP values of each AirP level were statistically significantly different from each other in pairwise comparison. In a linear mixed model, the effect of AirP on RVP was highly significant (p < 0.001). In the model, a 10-mmHg increase in AirP resulted in a linear increase in RVP of 2.2 mmHg.

CONCLUSION

An increase in AirP was accompanied by a linear increase in RVP. The influence of AirP on RVP, and thus on retinal perfusion pressure during the Valsalva maneuver, is less than was assumed based on previous studies in which contact lens dynamometry was used.

Additional Guidance on the Use of the PRESERFLO™ MicroShunt in the Treatment of Glaucoma: Insights from a Second Delphi Consensus Panel

INTRODUCTION

The PRESERFLO™ MicroShunt (PMS) has been proven to significantly lower intraocular pressure (IOP) in patients with glaucoma and has been available for use since 2019. With increasing published evidence and growing experience of glaucoma surgeons, the aim of this modified Delphi panel was to build on the findings of a previous Delphi panel conducted in 2021 and provide further guidance on the role of the PMS to treat patients with glaucoma in Europe.

METHODS

Thirteen European glaucoma surgeons experienced in the PMS procedure participated in a 3-round modified Delphi panel. A targeted literature review and expert steering committee guided Round 1 questionnaire development. Consensus was pre-defined at a threshold of ≥ 70% of panellists selecting 'strongly agree'/'agree' or 'strongly disagree'/'disagree' for 6-point Likert scale questions or ≥ 70% selecting the same option for multiple or single-choice questions. Questions not reaching consensus were restated/revised for the next round, following guidance from free-text responses/scoping questions.

RESULTS

In total, 28% (n = 9/32), 52% (n = 16/31) and 91% (n = 10/11) of statements reached consensus in Rounds 1, 2 and 3, respectively. There was agreement that the PMS may be used in patients with pigmentary, post-trauma or post-vitrectomy glaucoma and for patients with uveitic glaucoma without active inflammation. The PMS may be more suitable for patients with contact lenses than other subconjunctival filtering surgeries, without eliminating bleb-associated risks. Consensus was reached that combining PMS implantation and phacoemulsification may be as safe as standalone PMS surgery, but further efficacy data are required. Following a late rise in IOP ≥ 4 months post-surgery, topical aqueous suppressant drops or bleb revision may be suitable management options.

CONCLUSIONS

This Delphi panel builds on the considerations explored in the 2021 Delphi panel and provides further detailed guidance for glaucoma surgeons on the use of the PMS, reflecting the availability of novel evidence and surgical experience. Videos are available for this article.

PRESERFLO ™ MicroShunt versus trabeculectomy: 1-year results on efficacy and safety

PURPOSE

To compare the efficacy and safety of the PRESERFLO™ MicroShunt versus trabeculectomy in patients with primary open-angle glaucoma (POAG) after one year.

PATIENTS AND METHODS

Institutional prospective interventional cohort study comparing eyes with POAG, which had received the PRESERFLO™ MicroShunt versus trabeculectomy. The MicroShunt group was matched with the trabeculectomy group for age, known duration of disease, and number and classes of intraocular pressure (IOP) lowering medications to have similar conjunctival conditions. The study is part of the Dresden Glaucoma and Treatment Study, using a uniform study design, with the same inclusion and exclusion criteria, follow-ups and standardized definitions of success and failure for both procedures.

PRIMARY OUTCOME MEASURES

mean diurnal IOP (mdIOP, mean of 6 measurements), peak IOP, and IOP fluctuations.

SECONDARY OUTCOME MEASURES

success rates, number of IOP lowering medications, visual acuity, visual fields, complications, surgical interventions, and adverse events.

RESULTS

Sixty eyes of 60 patients, 30 in each group, were analyzed after 1-year follow-ups. Median [Q25, Q75] mdIOP (mmHg) dropped from 16.2 [13.8-21.5] to 10.5 [8.9-13.5] in the MicroShunt and from 17.6 [15.6-24.0] to 11.1 [9.5-12.3] in the trabeculectomy group, both without glaucoma medications. Reduction of mdIOP (P = .596), peak IOP (P = .702), and IOP fluctuations (P = .528) was not statistically significantly different between groups. The rate of interventions was statistically significantly higher in the trabeculectomy group, especially in the early postoperative period (P = .018). None of the patients experienced severe adverse events.

CONCLUSION

Both procedures are equally effective and safe in lowering mdIOP, peak IOP and IOP fluctuations in patients with POAG, one year after surgery.

CLINICAL TRIAL REGISTRATION

NCT02959242.

Estimating pulsatile ocular blood volume from intraocular pressure, ocular pulse amplitude, and axial length

The purpose of this study was to develop a method of estimating pulsatile ocular blood volume (POBV) from measurements taken during an ophthalmic exam, including axial length and using a tonometer capable of measuring intraocular pressure (IOP) and ocular pulse amplitude (OPA). Unpublished OPA data from a previous invasive study was used in the derivation, along with central corneal thickness (CCT) and axial length (AL), as well as IOP from the PASCAL dynamic contour tonometer (DCT) and intracameral (ICM) measurements of IOP for 60 cataract patients. Intracameral mean pressure was set to 15, 20, and 35 mmHg (randomized sequence) in the supine position, using a fluid-filled manometer. IOP and OPA measurements were acquired at each manometric setpoint (DCT and ICM simultaneously). In the current study, ocular rigidity (OR) was estimated using a published significant relationship of OR to the natural log of AL in which OR was invasively measured through fluid injection. Friedenwald’s original pressure volume relationship was then used to derive the estimated POBV, delivered to the choroid with each heartbeat as a function of OR, systolic IOP (IOP_sys), diastolic IOP (IOP_dia), and OPA, according to the derived equation POBV = log (IOP_sys/IOP_dia) / OR. Linear regression analyses were performed comparing OPA to OR and calculated POBV at each of the three manometric setpoints. POBV was also compared to OPA/IOP_dia with all data points combined. Significance threshold was p < 0.05. OR estimated from AL showed a significant positive relationship to OPA for both DCT (p < 0.011) and ICM (p < 0.006) at all three manometric pressure setpoints, with a greater slope for lower IOP. Calculated POBV also showed a significant positive relationship to OPA (p < 0.001) at all three setpoints with greater slope at lower IOP, and a significant negative relationship with IOP_dia. In the combined analysis, POBV showed a significant positive relationship to OPA/ IOP_dia (p < 0.001) in both ICM and DCT measurements with R² = 0.9685, and R² = 0.9589, respectively. POBV provides a straight-forward, clinically applicable method to estimate ocular blood supply noninvasively. Higher IOP in combination with lower OPA results in the lowest values of POBV. The simplified ratio, OPA/ IOP_dia, may also provide a useful clinical tool for evaluating changes in ocular blood supply in diseases with a vascular component, such as diabetic retinopathy and normal tension glaucoma. Future studies are warranted.

Evaluation of corneal biomechanical properties using the ocular response analyzer and the dynamic Scheimpflug-Analyzer Corvis ST in high pressure and normal pressure open-angle glaucoma patients

PURPOSE

To characterize differences in corneal biomechanics in high (HPG) and normal pressure (NPG) primary open-angle glaucoma, and its association to disease severity.

METHODS

Corneal biomechanical properties were measured using the Ocular Response Analyzer (ORA) and the dynamic Scheimpflug-Analyzer Corvis ST (CST). Disease severity was functionally assessed by automated perimetry (Humphrey field analyzer) and structurally with the Heidelberg Retina Tomograph. To avoid a possible falsification by intraocular pressure, central corneal thickness and age, which strongly influence ORA and CST measurements, group matching was performed. Linear mixed models and generalized estimating equations were used to consider inter-eye correlation.

RESULTS

Following group matching, 60 eyes of 38 HPG and 103 eyes of 60 NPG patients were included. ORA measurement revealed a higher CRF in HPG than in NPG (P < 0.001). Additionally, the CST parameter integrated radius (P < 0.001) was significantly different between HPG and NPG. The parameter SSI (P < 0.001) representing corneal stiffness was higher in HPG than in NPG. Furthermore, regression analysis revealed associations between biomechanical parameters and indicators of disease severity. In HPG, SSI correlated to RNFL thickness. In NPG, dependencies between biomechanical readings and rim area, MD, and PSD were shown.

CONCLUSION

Significant differences in corneal biomechanical properties were detectable between HPG and NPG patients which might indicate different pathophysiological mechanisms underlying in both entities. Moreover, biomechanical parameters correlated to functional and structural indices of diseases severity. A reduced corneal deformation measured by dynamic methods was associated to advanced glaucomatous damage.

PRESERFLO™ MicroShunt versus trabeculectomy: first results on efficacy and safety

PURPOSE

To report efficacy and safety outcomes of the PRESERFLO™ MicroShunt compared with trabeculectomy, the current gold-standard treatment for advanced glaucoma, in the early and intermediate postoperative period.

METHODS

Institutional prospective interventional cohort study of primary open-angle glaucoma (POAG) patients scheduled for the PRESERFLO™ MicroShunt. The comparison group were POAG patients who had had received trabeculectomy and were matched for age, known duration of disease, number and classes of intraocular pressure (IOP)-lowering medications to ensure a similar conjunctival condition. The study is part of the Dresden Glaucoma and Treatment Study (DGTS), was not randomized, but used a uniform study design, with the same inclusion and exclusion criteria as well as standardized definitions of success and failure.

MAIN OUTCOME MEASURES

mean diurnal IOP (mdIOP, mean of 6 measurements), diurnal peak IOP, diurnal IOP fluctuations, glaucoma medical therapy, success rates, visual acuity, visual fields, surgical complications and interventions, and severe adverse events.

RESULTS

Fifty-two eyes of 52 patients, 26 in each group, were analysed. At 6 months, median [Q25, Q75] mdIOP was 10.8 [9.5-12.2] mmHg in the microshunt and 10.3 [7.6-11.8] mmHg in the trabeculectomy group. Reduction in mdIOP (p = 0.458), peak diurnal IOP (p = 0.539), and median diurnal fluctuation (p = 0.693) was not statistically significantly different between groups. The rate of interventions was statistically significantly higher in the trabeculectomy compared with the microshunt group (p = 0.004). None of the patients experienced severe adverse events.

CONCLUSION

Both procedures are equally effective and safe in lowering mdIOP in patients with POAG. Because the microshunt is less invasive with less follow-up and interventions needed postoperatively, it might be recommended earlier in the treatment of glaucoma.

2-Jahres-Ergebnisse nach transskleraler MicroPulse-Lasertherapie bei Patienten mit primärem Offenwinkelglaukom

Hintergrund Untersuchung der langfristigen Effizienz und Sicherheit der transskleralen Lasertherapie (TLT) mittels MicroPulse über 24 Monate bei Patienten mit primärem Offenwinkelglaukom (POWG).

Material und Methoden In dieser prospektiven interventionellen Fallserie wurden die Daten von 44 Augen von medikamentös behandelten POWG-Patienten ausgewertet, die eine MicroPulse-TLT erhielten, um eine weitere Senkung des Augeninnendrucks (IOD) zu erreichen. Es wurden die Reduktion des 24-h-IODs, der zirkadianen IOD-Fluktuationen und der IOD-Spitzen nach 3, 12 und 24 Monaten untersucht. Zudem sollten postoperative Komplikationen, die Misserfolgsquote und Einflussfaktoren auf den Therapieerfolg analysiert werden.

Ergebnisse Der IOD ist von 16,1 ± 3,4 mmHg präoperativ auf 13,0 ± 2,9 mmHg (n = 31; p < 0,001) nach 3 Monaten, 12,3 ± 3,0 mmHg (n = 27; p < 0,001) nach 12 Monaten und 13,1 ± 2,6 mmHg (n = 23; p < 0,001) nach 24 Monaten gesunken. Nach 24 Monaten erreichten 23 Augen (52%) ihren individuellen Zieldruck. Es traten keine schwerwiegenden postoperativen Komplikationen auf. Es konnten keine Einflussfaktoren auf den Therapieerfolg identifiziert werden. Das häufigste Therapieversagen war innerhalb der ersten 3 postoperativen Monate zu beobachten und blieb danach nahezu stabil.

Schlussfolgerung Die MicroPulse-TLT zeigt eine gute IOD-Senkung bei Patienten mit primärem Offenwinkelglaukom und maximal tolerierter drucksenkender Lokaltherapie, wobei etwa 50% der Augen ihren individuellen Zieldruck erreichten.

Corneal Biomechanics in Glaucoma

Now that is possible to measure the biomechanical parameters of the cornea in vivo, scientific and clinical interest has increased in changes in these parameters in glaucoma. These parameters may act as biomarkers for early diagnosis, but also serve to emphasize the increased vulnerability to intraocular pressure, reduced blood flow or changing ocular perfusion pressure. Measuring and interpreting these parameters may help in achieving better and individually tailored glaucoma management.

Efficacy of Selective Laser Trabeculoplasty on Circadian Intraocular Pressure Following Trabeculectomy in Advanced Primary Open-angle Glaucoma

PRCIS

In about 50% of post-trabeculectomy (TE) eyes, selective laser trabeculoplasty (SLT) is effective in further lowering intraocular pressure (IOP).

PURPOSE

To investigate the efficacy and safety of SLT in post-TE eyes, uncontrolled on maximum tolerated medication, and/or with progression of visual field loss.

PATIENTS AND METHODS

This retrospective study consecutively included post-TE eyes of patients diagnosed with primary open-angle glaucoma who had been treated with 360 degrees SLT and had a follow-up after 12 months. Primary endpoints were the reduction of mean diurnal intraocular pressure (mdIOP, mean of 6 measurements), peak IOP, and diurnal IOP fluctuations. Secondary outcomes were factors influencing IOP reduction, SLT success, and failure rates.

RESULTS

Forty-three eyes of 43 patients were included. During the first year, 10 eyes (23%) needed additional procedures to reduce mdIOP and were accounted as failures and excluded from final analysis. Of the remaining 33 eyes (77%) mdIOP [Q25, Q75] dropped from 15.2 [12.2 to 16.5] to 13.2 [11.6 to 15.3] mm Hg (P=0.027), 23 eyes (54%) showed a sufficient mdIOP reduction, 1 year after SLT.

CONCLUSION

SLT is effective and safe in lowering mdIOP to target IOP in about 50% of eyes after prior incisional glaucoma surgery.

Measurement of the retinal venous pressure with a new instrument in healthy subjects

Background

The retinal venous pressure (RVP) is a determining factor for the blood supply of the retina as well as the optic nerve head and until recently has been measured by contact lens dynamometry (CLD). A new method has been developed, potentially offering better acceptance. The applicability and the results of both methods were compared.

Methods

The type of this study is cross sectional. The subjects were 36 healthy volunteers, age 26 ± 5 years (mean ± s). Tonometry: rebound tonometer (RT) (iCare). The measurements were performed during an increase in airway pressure of 20 mmHg (Valsalva manoeuvre). Principle of RVP measurement: the central retinal vein (CRV) is observed during an increase of intraocular pressure (IOP) and at the start of pulsation, which corresponds with the RVP. Two different instruments for the IOP enhancement where used: contact lens dynamometry and the new instrument, IOPstim. Principle: a deflated balloon of 8 mm diameter—placed on the sclera laterally of the cornea—is filled with air. As soon as a venous pulsation occurs, filling is stopped and the IOP is measured, equalling the RVP. Examination procedure: randomization of the sequence: CLD or IOPstim, IOP, mydriasis, IOP three single measurements (SM) of the IOP with RT or of the pressure increase with CLD at an airway pressure of 20 mmHg, 5 min break, IOP, and three SM using the second method at equal pressure (20 mmHg).

Results

Spontaneous pulsation of the CRV was present in all 36 subjects. Pressures are given in mmHg. IOP in mydriasis 15.6 ± 3.3 (m ± s). Median RVP (MRVP)) of the three SM: CLD/IOPstim, 37.7 ± 5.2/24.7 ± 4.8 (t test: p < 0.001). Range of SM: 3.2 ± 1.8/2.9 ± 1.3 (t test: p = 0.36). Intraclass correlation coefficient (ICC) of SM: 0.88/0.83. ANOVA in SM: p = 0.48/0.08. MRVP CLD minus MRVP IOPstim: 13.0 ± 5.6. Ratio MRVP CLD/MRVP IOPstim: 1.56 ± 3.1. Cooperation and agreeability were slightly better with the IOPstim.

Conclusion

This first study with the IOPstim in humans was deliberately performed in healthy volunteers using Valsalva conditions. As demonstrated by ICC and ANOVA, reproducible SM can be obtained by both methods and the range of the SM does not differ greatly. The higher MRVP in CLD could be explained by the different directions of the force vectors.

[Vasculat treatment concepts in glaucoma patients]

BACKGROUND

Approximately 40% of all open-angle glaucomas do not show high intraocular pressure (IOP). Vascular risk factors play an important role in the pathogeneses of normal pressure glaucoma but high pressure glaucoma is also often accompanied by significant vascular components.

OBJECTIVE

What are the practice relevant possibilities of vascular glaucoma treatment?

MATERIAL AND METHODS

An evaluation of scientific articles from PubMed dealing with vascular glaucoma was carried out.

RESULTS

The treatment of vascular risk factors in glaucoma patients requires a thorough medical history regarding vascular symptoms (peripheral vasospasm, tinnitus, migraine etc.) and information on the presence of systemic diseases. Furthermore, a 24h blood pressure profile and the determination of the fat metabolism status represent important and simple examinations.

CONCLUSION

Besides optimizing systemic blood pressure, reducing an increased central retinal venous pressure, treatment with statins, calcium channel blockers, Ginkgo biloba extract, increased physical exercise and fluid replacement are options to ameliorate vascular conditions. An interdisciplinary cooperation with general practitioners and internists is an important component of holistic treatment.

Comparison of Different Nutritional and Lifestyle Factors between Glaucoma Patients and an Age-Matched Normal Population

PURPOSE

To compare nutritional and lifestyle factors between glaucoma patients and an age-matched control group.

METHODS

One hundred and ninety (190) glaucoma patients were enrolled in this study. The control group comprised 97 age-matched participants. Data on physical activity, nicotine smoking, and several nutritional habits like coffee and alcohol consumption as well as high-salt and high-protein intake were collected using a standardised questionnaire.

RESULTS

Age and gender were not statistically significantly different between the groups. There was a tendency for higher physical activity in the glaucoma group in comparison to the control group (47.3 vs. 35.4%; p = 0.056). Statistically significantly more glaucoma patients were nonsmokers (n = 169; 89.4%) compared to the control group (n = 64; 66.7%; p = 0.001). Glaucoma patients were also more often teetotal compared to the control group (21.6% compared to 14.4%; p < 0.001). Similarly, more glaucoma patients drank larger amounts of coffee in comparison to the control group (p = 0.001). One hundred and seventy-six (96.7%) glaucoma patients and 88 (90.7%) control subjects had high-protein intake (p = 0.035). High-salt intake was significantly lower in the glaucoma group (69.3 vs. 73.2%; p = 0.018). Of the 190 glaucoma patients, 81 had early visual field impairments (MD > - 6 dB) and 109 patients had moderate (MD between - 6 dB and - 12 dB) to severe (MD < - 12 dB) visual field defects. The severity of visual field defects, whether early, moderate, or severe, had no statistically significant impact on lifestyle parameters.

CONCLUSION

Contrary to our original hypothesis that glaucoma patients would tend to follow an unhealthier lifestyle than the control group, the opposite was seen. Presumably, the cause of this healthier lifestyle is the desire to contribute positively through the course of the disease.

The Distribution of Retinal Venous Pressure and Intraocular Pressure Differs Significantly in Patients with Primary Open-Angle Glaucoma

INTRODUCTION

Until now, venous pressure within the eye has widely been equated with intraocular pressure (IOP). Measurements with dynamometers calibrated in instrument units or in force showed that the retinal venous pressure (RVP) may be higher than the IOP in glaucoma patients. In this study, the RVP was measured with a contact lens dynamometer calibrated in mmHg.

METHODS

Study type: cross-sectional.

SUBJECTS

Fifty consecutive patients with primary open-angle glaucoma (POAG) who underwent diurnal curve measurement under medication. Age: 69 ± 8 years. Measurement of RVP: contact lens dynamometry. IOP measurement: dynamic contour tonometry.

RESULTS

Pressures are given in mmHg. In all 50 patients, the IOP was 15.9 (13.6; 17.1) [median (Q1; Q3)], and the RVP was 17.4 (14.8; 27.2). The distribution of the IOP was normal and that of the RVP was right skewed. In the subgroup of 34 patients with spontaneous pulsation of the central retinal vein (SVP), the IOP and therefore, by definition, the RVP was 16.5 (13.7; 17.4). In the subgroup of 16 patients without SVP, the IOP was 14.8 (13.3; 16.4), and the RVP was 31.3 (26.2; 38.8) (p ≤ 0.001). In systemic treatment, the prescribed drugs were (the number of patients is given in parentheses): ACE inhibitors (20), β-blockers (17), angiotensin II-receptor blockers (13), calcium channel blockers (12), diuretics (7). No difference in RVP was observed between patients receiving these drugs and not receiving them, except in the β-blocker group. Here, the 17 patients with systemic β-blockers had a median RVP of 15.6 mmHg and without 20.2 mmHg (p = 0.003). In the 16 patients with a higher RVP than IOP, only one patient received a systemic β-blocker. The median IOP was 15.7 mmHg with systemic β-blockers and 16.1 mmHg without (p = 0.85).

CONCLUSION

In a subgroup of 16 of the 50 patients studied, the RVP was greater than the IOP by a highly statistically and clinically significant degree. According to the widely accepted thinking on the pathophysiology of retinal and optic nerve head circulation, the blood flow in these tissues may be much more compromised in this group of patients than has been assumed. They may be identified by a missing SVP. Topical and systemic medications showed no statistically significant influence on the RVP, except for the systemic β-blockers, in which the RVP was lower by 4.6 mmHg than for the patients who did not receive these drugs (p = 0.003).

Scheimpflug Corneal Densitometry Changes After Trabeculectomy

PURPOSE

To study the possible changes in Scheimpflug corneal densitometry 6 months after mitomycin C-augmented trabeculectomy and to compare these measurements with healthy controls.

METHODS

Corneal densitometry was monitored with the Pentacam HR3 before and 6 months after first-time uncomplicated mitomycin C-augmented trabeculectomy in 42 eyes of 42 white patients with open-angle glaucoma and in 22 healthy age-matched controls. Preoperative intraocular pressure (IOP), central corneal thickness, known duration of the disease, gender, the type and number of substances, applications and amount of benzalkonium chloride per day, and postoperative topical cortisone use were tested for possible correlations in the trabeculectomy group.

RESULTS

There was a statistically significant reduction of mean diurnal IOP from 19.0 ± 7.7 to 11.1 ± 7.7 mm Hg (P = 0.003) and the amount of pressure-lowering substances from 3.7 ± 1.0 to 0.1 ± 0.5 (P < 0.001). Densitometry measurements decreased in the entire cornea from 25.5 ± 5.7 to 23.1 ± 5.8 grayscale units (P = 0.001) with emphasis in the anterior layer. They returned close to normal 6 months after trabeculectomy and were not statistically significantly different compared with a healthy control group (22.8 ± 3.4 grayscale unit; P = 0.824). No correlations could be found with these observations and possible causing factors studied.

CONCLUSIONS

Corneal densitometry, an objective and sensitive measure of corneal transparency, returned close to normal 6 months after trabeculectomy. Although the observations cannot be associated with any causing factor in this study, the significant IOP reduction and the nearly complete cessation of topical antiglaucomatous substances including benzalkonium chloride seem to be the most plausible reasons for this finding.

A new biomechanical glaucoma factor to discriminate normal eyes from normal pressure glaucoma eyes

BACKGROUND

To test the ability of the newly calculated Dresden biomechanical glaucoma factor (DBGF) based on dynamic corneal response (DCR) deformation and corneal thickness parameters, to discriminate between healthy and normal pressure glaucoma (NPG) eyes.

METHODS

Seventy healthy and 70 NPG patients of Caucasian origin were recruited for this multicentre cross-sectional pilot study, which included both eyes for analysis. Logistic regression analysis with generalized estimating equation (GEE) models to account for correlations between eyes and a threefold cross-validation were performed to determine the optimal combination of Corvis ST parameters in order to separate normal from NPG eyes.

RESULTS

The DBGF was calculated using 5 Corvis ST parameters, which showed the best discrimination power: deformation amplitude ratio progression, highest concavity time, pachymetry slope, the biomechanically corrected intraocular pressure and pachymetry. In a threefold cross-validation, the receiver operating characteristic (ROC) curve confirmed an area under the curve (AUC) of 0.814 with a sensitivity of 76% and a specificity of 77% using a logit cut-off value of a DBGF = 0.5.

CONCLUSION

The DBGF shows to be sensitive and specific to discriminate healthy from NPG eyes. Since diagnosis of NPG is often challenging, the DBGF may help with the differential diagnosis of NPG in daily clinical practice. Therefore, it might be considered as a new possible screening method for NPG.

Argon laser peripheral iridoplasty for chronic primary angle-closure and angle-closure glaucoma in caucasians

PURPOSE

To investigate whether the peripheral thinning and shrinking of the iris as induced with Argon laser peripheral iridoplasty (ALPI) has an effect on intraocular pressure (IOP), angle structure and 3-D anterior segment (AS) morphology in Caucasians with chronic primary angle-closure (PAC) and primary angle-closure glaucoma (PACG).

METHODS

Twenty-four eyes of 24 patients (age 67.7 ± 8.9 years; seven males; 17 females) diagnosed with PAC (n = 10) or PACG (n = 14) were assigned for ALPI prior to laser peripheral iridotomy (LPI) and consecutively enrolled in this prospective interventional study. Intraocular pressure (IOP) was measured with Goldmann applanation tonometry, angle structure with gonioscopy using the Shaffer grading system and AS morphology with the Pentacam rotating Scheimpflug camera prior to and 3 months after ALPI. Intraocular pressure (IOP)-lowering medication was not changed during follow-up.

RESULTS

Intraocular pressure (IOP) changed statistically significantly from 18.8 ± 3.6 to 14.7 ± 3.1 mmHg (p < 0.001). Gonioscopy showed a statistically significant angle widening in all four quadrants: nasally from Shaffer 1.04 ± 0.98 to 2.54 ± 1.1 (p < 0.001), superiorly from 0.39 ± 0.66 to 1.58 ± 1.21 (p < 0.001), temporally from 0.87 ± 1.01 to 2.17 ± 1.24 (p = 0.001) and inferiorly from 1.22 ± 0.74 to 2.75 ± 0.9 (p < 0.001). Pentacam parameters like anterior chamber depth, volume and angle did not increase statistically significantly.

CONCLUSION

Argon laser peripheral iridoplasty (ALPI) is a safe and effective procedure for reducing appositional angle-closure and thus IOP in nonacute PAC and PACG patients.

Effect of selective laser trabeculoplasty on ocular haemodynamics in primary open-angle glaucoma

PURPOSE

Selective laser trabeculoplasty (SLT) is known to reduce intraocular pressure (IOP) effectively. The aim of this study, however, was to evaluate the effect of SLT on ocular haemodynamics.

METHODS

A total of 69 eyes of 69 patients (age 67.8 ± 9.9 years) with already treated primary open-angle glaucoma who were assigned for SLT for further IOP reduction were consecutively enrolled in this prospective interventional case series. Intraocular pressure, the ocular pulse amplitude (OPA), ocular pulse volume (OPV) and pulsatile ocular blood flow (pOBF) were assessed with the Ocular Blood Flow Analyzer prior to and 3 months after SLT.

RESULTS

Intraocular pressure was statistically significantly reduced from 16.0 ± 5.4 mmHg to 12.8 ± 4.0 mmHg (p = 0.001). The OPA did not change (p = 0.783) after IOP reduction following SLT. OPV and pOBF increased statistically significantly. OPV increased from 7.33 ± 3.05 to 8.59 ± 3.35 μl (17.2%; p = 0.001) and pOBF from 17.11 ± 5.42 to 19.74 ± 6.59 μl/s (15.4%; p = 0.002).

CONCLUSION

Selective laser trabeculoplasty probably does not induce any pharmacological changes effecting systemic blood pressure or ocular blood flow as topical IOP-lowering medication might do, nor does it change biomechanical properties of the eye as surgery could. Therefore, an increase in ocular blood flow following SLT can only be explained by the reduction in IOP and might be a sign of dysfunctional autoregulation in glaucoma patients.

Preoperative intraocular pressure as a predictor of selective laser trabeculoplasty efficacy

PURPOSE

To identify predictors of intraocular pressure (IOP) reduction following selective laser trabeculoplasty (SLT) in patients with high- and low-pressure primary open-angle glaucoma, who are already taking maximally tolerated IOP-lowering medication and need further IOP reduction.

METHODS

In this prospective interventional case series, 157 eyes of 157 open-angle glaucoma patients who were assigned for SLT for further IOP reduction were included. Each patient had diurnal IOP measurements taken before and on average 6 months following SLT. The mean of six IOP measurements was compared. The following parameters were analysed for their association with SLT success: age, gender, spherical equivalent, high-pressure or normal-pressure open-angle glaucoma, number and type of pressure-lowering medications, lens status, pre-SLT IOP, IOP at the time of diagnosis, duration of glaucoma, visual field stage and central corneal thickness.

RESULTS

The only parameter that was predictive for absolute and relative mean diurnal IOP reduction after SLT was the preoperative mean diurnal IOP. One hundred per cent of the patients with a mean diurnal preoperative IOP of more than 18 mmHg had an IOP reduction after SLT. With mean diurnal preoperative values of 14-18 mmHg, 83.1% of the patients, and with values below 14 mmHg only 64% of the patients, showed an IOP reduction. This difference was statistically significant (>18 compared to 14-18: p = 0.002; >18 compared to <14: p = 0.001; 14-18 compared to <14: p = 0.030).

CONCLUSIONS

The pressure-lowering effect of SLT can best be predicted by the individual IOP level before treatment. Patients with mean diurnal IOP levels below 14 mmHg might not benefit from the procedure at all.

Effect of selective laser trabeculoplasty on corneal biomechanics

PURPOSE

To evaluate the effect of selective laser trabeculoplasty (SLT) on ocular biomechanics as measured with the ocular response analyzer (ORA, AMETEK Inc. and Reichert Inc.).

METHODS

In a prospective case series, 52 eyes of 52 patients (aged 66.6 ± 9.6 years) with insufficient intraocular pressure (IOP) control despite maximum tolerated medical therapy underwent SLT (Solo(™) SLT, Ellex Inc.) for further IOP reduction. Goldmann-correlated IOP (IOPg), corneal-compensated IOP (IOPcc), corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with the ORA prior to and at least 4 weeks following SLT.

RESULTS

IOPg decreased statistically significantly from 18.0 ± 6.4 to 14.8 ± 3.8 mmHg and IOPcc from 20.2 ± 6.5 to 16.7 ± 3.4 mmHg (p < 0.001). CH increased from 8.53 ± 2.03 to 9.12 ± 1.83 mmHg (p = 0.028) and CRF decreased from 9.58 ± 2.18 to 9.1 ± 2.1 mmHg (p = 0.037), which was statistically significant. Correcting the CH and CRF data for the influence of IOP reduction with a covariance analysis, however, resulted in an unchanged CH (IOPg adjusted: p = 0.318; IOPcc adjusted: p = 0.468) and CRF (IOPg adjusted: p = 0.320; IOPcc adjusted: p = 0.464) after SLT.

CONCLUSION

Selective laser trabeculoplasty does not change corneal biomechanical properties as measured with the ORA in already pretreated patients with glaucoma. The measured increase in CH and decrease in CRF can be solely explained by IOP reduction.

Analyzing biomechanical parameters of the cornea with glaucoma severity in open-angle glaucoma

PURPOSE

The purpose was to investigate a possible association of corneal hysteresis (CH) and corneal resistance factor (CRF) with open-angle glaucoma and the severity of disease.

METHODS

In this prospective cross-sectional study we recruited 86 open-angle glaucoma patients, 16 patients with ocular hypertension (OHT,) and 44 age-matched controls. Each participant had a complete glaucoma workup including measurements with the Ocular Response Analyzer and computerized perimetry with the Humphrey 30-2 SITA Standard program. Visual field damage was based on mean deviation (MD) and considered as early glaucomatous with a MD > - 6 dB, moderate glaucomatous between -6 and -12 dB and advanced glaucomatous < -12 dB. The association between ORA parameters, glaucoma, and disease severity was evaluated using univariate and multivariate linear regression analyses.

RESULTS

There was a statistically significant correlation between the biomechanical parameters and intraocular pressure, central corneal thickness, axial length, and age. On average, glaucoma patients had the lowest adjusted CH (8.96 ± 1.43 mmHg) and CRF (9.07 ± 1.93 mmHg) values in comparison to OHT patients (CH: 10.2 ± 1.5 mmHg; CRF: 10.6 ± 2.1 mmHg) and controls (CH: 9.7 ± 1.4 mmHg; CRF: 10.2 ± 1.9 mmHg). This difference was statistically significant (CH: p = 0.003; CRF: p = 0.008). There was also a statistically significant difference in adjusted CH (p = 0.001) and CRF (p = 0.004) values between the controls and the visual field groups, with the lowest values being in the most advanced group.

CONCLUSIONS

Before interpreting corneal biomechanical parameters, it seems important to adjust the measured data for their underlying influencing factors. Glaucoma patients with lower adjusted CH and CRF probably have more advanced disease and should, therefore, be treated more aggressively and monitored more carefully and frequently.

Nocturnal blood pressure in primary open-angle glaucoma

PURPOSE

To evaluate the nocturnal blood pressure (BP) dipping-pattern in patients with manifest primary open-angle glaucoma (POAG) and to find possible associations with the severity of visual field damage.

METHODS

A number of 314 patients suffering from POAG were consecutively enrolled in this cross-sectional hospital-based study. Each patient had diurnal intraocular pressure (IOP) measurements, 24-hr BP monitoring and computerized perimetry with the Humphrey 30-2 sita Standard program. Inclusion criteria were a mean IOP of less than 15 mmHg with fluctuations of less than 5 mmHg and a visual acuity of at least 20/40. One eye was randomly selected. Based on the night-day BP ratio, a mean arterial nocturnal BP drop of less than 10% was considered as non-dipping, between 10% and 20% as physiological dipping and of more than 20% as over-dipping.

RESULTS

Glaucoma patients with daytime systemic normotension on the average had more visual field loss in the over-dipper group (MD = - 16.6 dB, IQR = -18.9 to -2.7 dB) than glaucoma patients with daytime systemic hypertension, who had less visual field defects in the over-dipper group (MD = -3.9 dB, IQR = -6.2 to -1.9 dB) (p = 0.004). This result was also found taking age, glaucoma duration, visual acuity, gender, systemic and topical medication as covariates into account.

CONCLUSIONS

To judge the nocturnal BP situation of an individual patient, it is important to do this in relation to the daytime BP level. Twenty-four-hour BP evaluation might be important for all patients with POAG, as nocturnal BP could be a modifiable risk factor for glaucoma severity and progression.