The influence of altitude on the differences between Goldmann tonometry and Pascal dynamic contour tonometry: An ecological meta-analysis.

PURPOSE: A meta-analysis found that including atmospheric pressure as altitude in generalized linear models reveals higher differences between Goldmann tonometry and Pascal dynamic contour tonometry at higher altitudes, with the difference increasing in thinner corneas. To examine the difference in intraocular pressure (IOP) measurements by using Goldman applanation tonometry (GAT) and dynamic contour tonometer (DCT) tonometry in published literature and determine the influence of central corneal thickness (CCT), age, and altitude on that difference. METHODS: Articles that compare GAT and DCT were selected for an extensive literature review, and the location and altitude of the research centers were found online. CCT and age were analyzed as covariates, when available. RESULTS: A total of 157 studies including 24,211 eyes of 20,214 patients were included in the study. The results showed that the difference between DCT and GAT was higher at higher altitudes above sea level and increased with thinner corneas. However, the results were different in eyes with corneal transplants, where altitude and CCT had less influence, and in those post-refractive surgery where age was found to influence the difference. Theoretical correction formulas using altitude, CCT, and age were derived from this meta-analysis, but their accuracy and usefulness in clinical practice need validation. CONCLUSION: The findings suggest that there is a higher risk of underestimating IOP when the Goldmann tonometer is used at a higher altitude, particularly in eyes with glaucoma, thinner corneas, or corneal refractive surgery. Further research is needed to validate the accuracy of the correction formulas derived from this meta-analysis in clinical practice.

Preserflo TM MicroShunt implantation combined with Ologen TM in primary and secondary glaucoma patients in a clinical setting.

PURPOSE: This study aims to assess the effectiveness and safety of combining the Preserflo™ MicroShunt implant (MicroShunt) with a simultaneous Ologen™ implant in patients with glaucoma. METHODS: We conducted a retrospective study on consecutive patients with medically uncontrolled glaucoma who underwent MicroShunt + Ologen implantation as a standalone procedure or in combination with phacoemulsification (combined procedure). Success was defined as achieving an intraocular pressure (IOP) of 6-15 mmHg at 18 months post surgery, with a preoperative IOP reduction of at least 20%, and without (complete success) or with (qualified success) the need for antiglaucoma medications. The primary endpoint was the success rate. RESULTS: Forty-eight eyes from 47 patients were included, with 28 eyes (58.3%) undergoing the standalone procedure and 20 eyes (41.7%) undergoing the combined procedure. Overall, there was a significant reduction in preoperative IOP from 19.7 ± 5.8 mmHg to 11.4 ± 2.6 mmHg at 18 months ( P < 0.0001). In the standalone procedure group, preoperative IOP decreased from 21.5 ± 5.2 mmHg to 11.7 ± 2.5 mmHg ( P < 0.0001), and in the combined procedure group, preoperative IOP decreased from 17.1 ± 5.8 mmHg to 10.9 ± 2.7 mmHg ( P = 0.0002), with no significant difference between the two groups regarding final IOP. The mean number of antiglaucoma medications significantly decreased from 3.2 ± 1.1 to 0.3 ± 0.7 in the overall study population ( P < 0.0001). At 18 months, 40 eyes (83.3%) were classified as successful. Regarding safety, out of the total number of eyes, two (4.2%) experienced choroidal detachment without visual impairment, two (4.2%) had transient hyphema, one (2.1%) showed reactivation of a corneal herpetic ulcer, one (2.1%) had diplopia, and one (2.1%) exhibited a shallow anterior chamber during the first week. CONCLUSION: The combination of Ologen™ and Preserflo™ MicroShunt, either alone or in conjunction with phacoemulsification, demonstrated a favorable profile in terms of IOP reduction and safety.

New Gonioscopy Technique for Finding Schwalbe's Line: The Ortiz Maneuver.

A new technique for performing gonioscopy that facilitates finding Schwalbe´s line, and lowers the amount of time and light that enters through the pupil is presented. The technique is an alternative to the classic corneal wedge technique and is feasible in the horizontal quadrants without further adjustments to the slit lamp, in contrast to the tilting usually needed for these quadrants. Clinical photos and online videos are presented. How to cite this article: Albis-Donado O, Ortiz-Arismendi GE, Bhartiya S. New Gonioscopy Technique for Finding Schwalbe's Line: The Ortiz Maneuver. J Curr Glaucoma Pract 2023;17(1):37-39.

Effects of Acute Atmospheric Pressure Changes on Dynamic Contour Tonometry and Goldmann Applanation Tonometry in Normal Individuals: A Pilot Study.

PRéCIS:: Intraocular pressure (IOP) measurement differences with Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) are affected by atmospheric pressure inside a hyperbaric chamber. PURPOSE: To compare IOP measurements obtained with GAT and DCT in 22 normal individuals at different atmospheric pressures simulated in a hyperbaric chamber. METHODS: The IOP of both eyes of 22 healthy volunteers was measured using GAT and DCT at 4 different atmospheric pressure levels.Starting at 1 Queretaro atmospheric pressure (QATM), the IOP was measured with GAT and DCT. The atmospheric pressure was then increased to 1.1 QATM (equivalent to 1032 m above sea level), 1.2 QATM (equivalent to 315 m above sea level), and 1.25 QATM (equivalent to sea level), starting 5 minutes after reaching each level. The limits of agreement between various measurements with each tonometer were calculated using the Bland-Altman plots. RESULTS: The first 4 subjects were used to measure feasibility, consistency, variability, and the time needed for IOP to return to baseline after each atmospheric pressure increase.For the entire 44 eyes, the mean GAT IOP at 1 QATM was 12.23 mm Hg (range, 8 to 20 mm Hg; SD, 2.84) and mean DCT was 16.36 (range, 12.1 to 25.3; SD, 2.84), with a mean 4.14 mm Hg difference (range, -0.1 to 7.5 mm Hg; SD, 1.62; P<0.001).Using the second measurements of the first 4 subjects and those after 5 minutes of adaptation for the rest of the group at 1.1 QATM, mean GAT IOP was 11.05±2.68 mm Hg and mean DCT IOP was 15.60±3.02 mm Hg, for a mean difference between instruments of 4.56±1.81 mm Hg (P<0.001).At 1.2 QATM, mean GAT IOP was 11.14±2.53 mm Hg and mean DCT IOP was 15.39±2.91 mm Hg. The difference between instruments was 4.25±2.12 mm Hg (P<0.001).At 1.25 QATM, the mean GAT IOP was 12.39±3.11 mm Hg and mean DCT IOP was 14.91±2.73 mm Hg. The difference between instruments after 5 minutes of adaptation was 2.53±1.62 mm Hg (P<0.001).Generalized estimating equations for performing linear regression multivariable analysis using atmospheric pressure, expressed as altitude, and age as covariates, shows that the difference between GAT and DCT increases by 1 mm Hg per 673 m of increase of altitude above sea level. Age was not a significant predictor. CONCLUSIONS: Acute changes in atmospheric pressure induce changes in IOP measurements for both GAT and DCT and in different directions. Despite the limitation of sample size, it may be postulated that the difference of IOP measurements between the 2 tonometers increases with lower atmospheric pressures.

Citius, Altius, Fortius: Agreement between Perkins and Dynamic Contour Tonometry (Pascal) and the Impact of Altitude.

INTRODUCTION: To ascertain differences in intraocular pressure (IOP) measurement and their repeatability between dynamic contour tonometry (DCT) and Goldmann/Perkins applanation tonometry (GAT) at two different atmospheric pressures. MATERIALS AND METHODS: Forty-one eyes of 41 healthy consenting subjects were enrolled for this observational, cross-sectional study. Pachymetry and IOP measurements with DCT and GAT for both eyes of each subject at Acapulco (0 m from sea level) and at Mexico City (2,234 m from sea level) were done by the same observer. The IOP was compared between tonometers at each of the altitudes, and also for repeatability of each tonometer at different altitudes. Pearson's correlation coefficient and Bland-Altman plots were used to assess reliability of measurements and their differences at the two altitudes. RESULTS: The mean age of patients was 41.7 (28-66 years); 22 were females. Mean IOP with DCT was 16.1 ± 2.2 mm Hg at sea level and 15.9 ± 2.1 mm Hg at 2,234 m above sea level, not a significant difference. Mean GAT IOP at the two altitudes was 13.1 ± 1.8 and 11.5 ± 1.7 mm Hg respectively, a statistically sig -nificant difference. In contrast, central corneal thickness (CCT) was not significantly changed (548.3 to 549.4 µm, p = 0.496). CONCLUSION: Repeatability of single-observer measurements with GAT remains clinically acceptable, but not at different altitudes. The DCT seems to more consistently measure a similar IOP at different altitudes in the same subjects. The two tonometers may not be used interchangeably in the serial follow-up of patients at any of the altitudes.How to cite this article: Albis-Donado O, Bhartiya S, Gil-Reyes M, Casale-Vargas G, Arreguin-Rebollar N, Kahook MY. Citius, Altius, Fortius: Agreement between Perkins and Dynamic Contour Tonometry (Pascal) and the Impact of Altitude. J Curr Glaucoma Pract 2018;12(1):40-44.

Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy.

PURPOSE: To evaluate the ability of phacoemulsification combined with either primary trabeculectomy (PT) or primary Ahmed glaucoma valve implantation (PAVI) to achieve target intraocular pressures (TIOP) in adults with primary open angle glaucoma. MATERIALS AND METHODS: Chart review of 214 adult patients operated between January 2002 and June 2008 with a minimum follow-up of 6 months. Group 1 comprised 181 eyes of 166 patients undergoing PT while group 2 included 50 eyes of 49 patients in combination with primary AVI. Target lOPs were pre-determined for each patient and success was defined as an IOP at or lower than target with or without medications. An IOP above target, loss of light perception or need for additional procedures to lower IOP were considered a failure. RESULTS: Mean preoperative IOP was 17.2 mm Hg in group 1 and 17.3 in group 2. Mean postoperative IOPs were 10.2 and 9.2 on day 1, 12.2 and 11.6 at year 1, and 10.7 in both groups at year 5. Survival rates in groups 1 and 2 were 96.7 vs 96% at 6 months, 89 vs 96% at 12 months, 83.5 vs 96% at 24 months and 79.4 vs 89.1% at 36, 48 and 72 months. Transient bleb leaks were more frequent in group 1 (26 eyes, 14.4 vs 0%, p = 0.001) and transient choroidal detachments were more frequent in group 2 (7 eyes, 3.9 vs 6 eyes, 12%, p = 0.038). CONCLUSION: Midterm results for achieving target pressures using combined phacoemulsification with either PT or PAVI are comparable. The profile of complications is different for the two procedures. How to cite this article: Albis-Donado O, Sánchez-Noguera CC, Cárdenas-Gómez L, Castañeda-Diez R, Thomas R, Gil-Carrasco F. Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy. J Curr Glaucoma Pract 2015;9(1):6-11.

Results of a New Technique for Implantation of Nonrestrictive Glaucoma Devices.

OBJECTIVE: To describe and present results of an original technique for nonvalved glaucoma implants. PATIENTS AND METHODS: Thirty-five eyes of 34 patients with aggressive and/or advanced glaucomas of different causes were included. A Baerveldt implant was used in all cases, using an absorbable ligature that had been titrated to allow fow from day 1, but avoiding hypotony. Intraocular pressure (IOP) during the first 8 weeks, final IOP, visual acuity and complications were analyzed. RESULTS: Mean preoperative IOP was 42.8 mm Hg (range: 24-64 mm Hg). IOP was 14.4, 17.2, 18.6, 19 and 16.4 mm Hg during the 1, 2, 4, 6 and 8 postoperative weeks. Mean final IOP was 13.8 ± 4.25 mm Hg, a 67.8% reduction, after a mean follow-up time of 13 months (range: 8-29 months). Twenty-nine eyes (82.9%) had complete success, two had qualifed success (5.7%) and four were failures (11.4%). Choroidal detachments and transient tube obstructions were the most frequent complications. CONCLUSION: Titrated ligature of Baerveldt tubes was effective for controlling IOP during both the early and late postoperative phases in eyes with severe glaucomas. How to cite this article: Arismendi GEO, del Pilar Peña Valderrama C, Albis-Donado O. RESULTS of a New Technique for Implantation of Nonrestrictive Glaucoma Devices. J Current Glau Prac 2013;7(3):130-135.

Adjunctive bevacizumab in patients undergoing Ahmed valve implantation: a pilot study.

BACKGROUND AND OBJECTIVE: To report on preliminary findings of adjunctive subconjunctival bevacizumab (SCB) injections in patients undergoing Ahmed valve implantation (AVI) (New World Medical, Rancho Cucamonga, CA). PATIENTS AND METHODS: The study was approved by the institution's ethics committee. Patients were prospectively recruited during a 1-month period and randomized to receive AVI with postoperative SCB (days 1 and 7, n = 7) or AVI without SCB (n = 6). RESULTS: Baseline intraocular pressure (IOP) in the treatment (AVI+SCB) group was 19.4 ± 8.6 mm Hg, whereas baseline IOP in the control (AVI) group was 32.1 ± 17.7 mm Hg (P = .119). Final IOP was 13.8 mm Hg (n = 7) for the treatment group and 12.7 mm Hg for the control group (n = 5, P = .790). One eye in the control group required further glaucoma intervention at day 45 and was considered a failure. The pre-massage postoperative IOP was significantly lower for the treatment group only at day 45 (16.1 vs 26.0 mm Hg, P = .012). Mean post-massage IOP was significantly lower in the treatment group at day 15 (11.28 vs 17.16 mm Hg, P = .004), day 30 (11.28 vs 20.83 mm Hg, P = .015), and day 45 (12.16 vs 21.33 mm Hg, P = .001), and similar at month 3. Mean change in bleb area was 11.4 mm(2) in the treatment group and -0.4 mm(2) in the control group (P = .036 and P = .361, respectively, Student's paired samples t test). CONCLUSION: Bevacizumab was associated with a less aggressive hypertensive period as measured by post-massage IOP measurements, postoperative glaucoma medications, and cross-sectional bleb area by ultrasound. Further prospective studies are needed to better understand the utility of SCB at the time of AVI surgery.

Evaluation of Ahmed glaucoma valve implantation through a needle-generated scleral tunnel in Mexican children with glaucoma.

PURPOSE: To evaluate the results and extrusion rates of the Ahmed glaucoma valve (AGV) implantation through a needle-generated scleral tunnel, without a tube-covering patch, in children. MATERIALS AND METHODS: A retrospective review of the charts of 106 Mexican children implanted with 128 AGVs operated between 1994 and 2002, with the needle track technique, at our institution, with at least six months follow up was done. Main outcome measures were intraocular pressure (IOP) control, tube extrusions or exposure and other complications. RESULTS: Kaplan-Meier analysis demonstrated a 96.9% survival rate at six months, 82.4% at one year, 78.7% at two years, 70% at three years and 41.6% at four years. Total success at the last follow-up (IOP between 6 and 21 mm Hg without medications) was achieved in 30 eyes (23.5%), 58 eyes (45.3%) had qualified success (only topical hypotensive drugs) and 40 eyes (31.3%) were failures. The mean pre- and post-operative IOP at the last follow up was 28.4 mmHg (SD 9.3) and 14.5 mmHg (SD 6.3), respectively. No tube extrusions or exposures were observed. Tube-related complications included five retractions, a lens touch and a transitory endothelial touch. The risk of failure increased if the eye had any complication or previous glaucoma surgeries. CONCLUSION: Medium-term IOP control in Mexican children with glaucoma can be achieved with AGV implantation using a needle-generated tunnel, without constructing a scleral flap or using a patch to cover the tube. There were no tube extrusions, nor any tube exposures with this technique.