Goldmann Tonometry Research Articles

A Comparative Study of Rebound Tonometry With Tonopen and Goldmann Applanation Tonometry Following Vitreoretinal Surgery

To investigate agreement in intraocular pressure (IOP) measurements among Icare rebound tonometry, Tonopen tonometry, and Goldmann applanation tonometry following vitreoretinal surgery. Reliability analysis of tonometers. Fifty-eyes of 50 adults undergoing vitreoretinal surgery were enrolled. IOP was measured on first postoperative day using Icare (Tiolat, Helsinki, Finland), followed by Tonopen (Reichert, Depew, New York, USA) and Goldmann (Haag-Streit USA, Mason, Ohio, USA) in randomized order. Intraclass correlation coefficients (ICC) and Bland-Altman plots were calculated for all subcategories. Icare successfully measured IOP in all eyes, while Goldmann was unmeasurable in 6 eyes (12%) and Tonopen in 1 eye (2%). Mean IOP by Icare, Tonopen, and Goldmann was 15.9 ± 8.9, 16.9 ± 6.2, and 16.0 ± 7.3 mm Hg, respectively (P = .76). Type of intraocular tamponade, status of lens, status of cornea, gauge of instrumentation, and history of prior vitrectomy did not result in significant differences among the 3 tonometers. ICC was excellent (>0.75) in all subgroups, except at IOP <10 and ≥ 23 mm Hg (based on Icare). In eyes with IOP <10 mm Hg, Icare underestimated IOP (mm Hg; P = .01) compared to Goldmann (2.0 ± 2.1) and Tonopen (3.5 ± 2.4), whereas at IOP ≥ 23 mm Hg Icare was overestimated (P = .01) compared to Goldmann (3.77 ± 3.49) and Tonopen (4.97 ± 3.33). Overall, differences in IOP were ≤ 3 mm Hg in 58% of eyes for Icare-Tonopen, 72% for Tonopen-Goldmann, and 62% for Icare-Goldmann. IOP measurements using Icare rebound tonometry, Tonopen, and Goldmann tonometry are in excellent agreement following vitreoretinal surgery. However, Icare overestimates at IOP ≥ 23 and underestimates at IOP <10 mm Hg.

Biometric and intraocular pressure change after cataract surgery.

To evaluate changes in ocular biometric parameters with optical biometry and intraocular pressure (IOP) by Goldmann tonometry after uneventful phacoemulsification in normotensive eyes. This prospective study was composed of 117 eyes of 117 patients who had undergone uncomplicated phacoemulsification and foldable intraocular lens implantation. The measurements were obtained preoperatively and 1 month postoperatively. Axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter (PD), and lens thickness were measured by the LenStar optical biometer, and IOP was measured by Goldmann applanation tonometry. The relationships between IOP change and ocular biometric parameters were evaluated. Mean age was 64.73 ± 10.83 years; 45 patients were women (38.46%) and 72 patients were men (61.54%). Comparing preoperative and postoperative 1-month measurements, the mean AL, PD, and IOP decreased (p < 0.01), whereas ACD (p < 0.01) and CCT (p > 0.05) increased. Intraocular pressure change correlated positively with AL change (p < 0.05) and PD change (p < 0.05) and preoperative IOP (p < 0.01) and preoperative CCT (p < 0.05). Anterior chamber depth change correlated positively with preoperative ACD (p < 0.01) and negatively with preoperative PD (p < 0.05). Pupil diameter change positively correlated with preoperative PD (p < 0.01). Regression analyses showed that preoperative IOP significantly associated with postoperative IOP reduction according to the standardized coefficient beta (-0.649). Anterior segment morphometry changed and IOP decreased after phacoemulsification. The preoperative IOP may be the best parameter for estimating postoperative IOP reduction.

Quantitative corneal anatomy: evaluation of the effect of diabetes duration on the endothelial cell density and corneal thickness.

To evaluate the differences in endothelial cell density (ECD) and central corneal thickness (CCT) between type II diabetic patients and age-matched healthy controls, and determine the impact of time from diagnosis. This is a comparative study of 77 eyes of type II diabetic patients (33 males, 44 females) and 80 eyes of healthy subjects (42 males, and 38 females) whose ages ranged from 38 to 56 years. CCT, ECD, HbA(1c) levels, and Goldmann tonometry were measured. The CCT was significantly higher and the ECD significantly lower in long-term diabetic patients (10 years + since diagnosis) when compared with short-term diabetic patients (<1 year since diagnosis) and controls (both p < 0.001). No significant differences in CCT (p = 0.30) and ECD (p = 0.31) were found between control groups. Multivariate analysis of variance indicated that there was a significant effect of the diabetes duration in CCT and ECD. In diabetic patients, a two-way analysis of variance showed that CCT was significantly different for a 7.5% HbA(1c) cut-off value, and ECD for both 7.0% and 7.5% HbA(1c) cut-off values. Type II diabetes causes a significant alteration in corneal structure and function in the long term. Our study seems to confirm the effect of diabetes duration and poor glycaemic control on CCT and ECD changes.

A survey of current and anticipated use of standard and specialist equipment by UK optometrists.

To investigate current and anticipated use of equipment and information technology (IT) in community optometric practice in the UK, and to elicit optometrists' views on adoption of specialist equipment and IT. An anonymous online questionnaire was developed, covering use of standard and specialist diagnostic equipment, and IT. The survey was distributed to a random sample of 1300 UK College of Optometrists members. Four hundred and thirty-two responses were received (response rate=35%). Enhanced (locally commissioned) or additional/separately contracted services were provided by 73% of respondents. Services included glaucoma repeat measures (30% of respondents), glaucoma referral refinement (22%), fast-track referral for wet age-related macular degeneration (48%), and direct cataract referral (40%). Most respondents (88%) reported using non-contact/pneumo tonometry for intra-ocular pressure measurement, with 81% using Goldmann or Perkins tonometry. The most widely used item of specialist equipment was the fundus camera (74% of respondents). Optical Coherence Tomography (OCT) was used by 15% of respondents, up from 2% in 2007. Notably, 43% of those anticipating purchasing specialist equipment in the next 12months planned to buy an OCT. 'Paperless' records were used by 39% of respondents, and almost 80% of practices used an electronic patient record/practice management system. Variations in responses between parts of the UK reflect differences in the provision of the General Ophthalmic Services contract or community enhanced services. There was general agreement that specialised equipment enhances clinical care, permits increased involvement in enhanced services, promotes the practice and can be used as a defence in clinico-legal cases, but initial costs and ongoing maintenance can be a financial burden. Respondents generally agreed that IT facilitates administrative flow and secure exchange of health information, and promotes a state-of-the-art practice image. However, use of IT may not save examination time; its dynamic nature necessitates frequent updates and technical support; the need for adequate training is an issue; and security of data is also a concern. UK optometrists increasingly employ modern equipment and IT services to enhance patient care and for practice management. While the clinical benefits of specialist equipment and IT are appreciated, questions remain as to whether the investment is cost-effective, and how specialist equipment and IT may be used to best advantage in community optometric practice.

Cannabinoids: a novel treatment for glaucoma

AbstractPurpose Synthetic cannabinoids are emerging novel agents for the treatment of glaucoma. Although increased intraocular pressure (IOP) is a risk factor, associated retinal damage is of prime concern. This study determines the ability of cannabinoids to decrease IOP and confer neuroprotection.Methods Ocular hypertension was created in Sprague‐Dawley (SD) rats by ligating 3 of 4 episcleral veins. IOP increased by at least 5 mm Hg in the operated eye. Cannabinoids, O‐1812 (1%) or O‐2545 (1%), were administered topically. IOP was measured by Goldmann tonometry at baseline (‐30), 0, 30, 60 and 120 min. For neuroprotection experiments: excitotoxic retinal damage was induced by injecting NMDA (2 ul of 10 mM) intravitreally in SD rats. Cannabinoids were injected following NMDA induction. Full‐field Electroretinograms were recorded at baseline, 1 wk and 2 wk. ERG a‐wave amplitudes are expressed as a percentage of baseline.Results After treatment with O‐2545, IOP was significantly reduced to 11±0.9 mmHg after 60 min and to 12±1.1 mmHg after 120 min compared to baseline of 14±0.6 mmHg (p&lt;0.03, n=6). Similarly, O‐1812 treatment reduced IOP to 8.4±1.8 mmHg after 60 min and maintained for up to 120 min (p&lt;0.001, n=6). After 1 wk, NMDA (control) reduced a‐wave amplitude by 38±0.1% (p&lt;0.001, n=6) from baseline, O‐2545 by 46±0.02% (p&lt;0.001, n=6) and O‐1812 by 23±0.1% (p=0.004, n=6). After 2 wks, NMDA further decreased a‐wave amplitude by 48±0.1% (p&lt;0.001, n=6), O‐2545 by 39±0.03% (p&lt;0.05, n=6) and O‐1812 by 8±0.1% (p=0.08, n=6).Conclusion Topically applied cannabinoids are effective agents that reduce IOP and confer neuroprotection and are prime candidates for potential glaucoma treatment.

Comparison between Goldmann, Icare Pro and Corvis ST tonometry

PurposeTo compare intraocular pressure (IOP) between the new non-contact tonometer Corvis ST (CST), the Goldmann applanation tonometry (GAT) and Icare Pro rebound tonometer (PRO). MethodsA total of 178 eyes of 178 healthy subjects were selected for the study. Measurements of IOP were made in a random order with GAT, PRO and CST. Central corneal thickness (CCT) was determined by ultrasound pachymetry. The mean of three valid measurements of each variable was used in the statistical analysis. The relationship between the tonometers was established using Bland–Altman plots. ResultsMean IOP was 15.5±2.8mmHg for GAT, 15.4±2.8mmHg for CST, and 14.6±2.3mmHg for PRO. The mean differences between pairs of tonometers were: GAT-PRO=0.9±1.7mmHg (p<.001), GAT-CST: 0.1±2.2 (p=.398), and PRO-CST: −0.8±−0.7mmHg, p<0.001. A positive relationship was detected between CCT and the three tonometers: GAT: r=0.325, p<.001; PRO: r=0.385, p<.001, and CST: r=0.428; p<.001. ConclusionsThe differences found between PRO and GAT were significantly higher than those found between CST and GAT, which showed non-significant differences. The measurements of the three tonometers were affected by the CCT.

Épaisseur cornéenne centrale chez le mélanoderme sénégalais atteint de glaucome primitif à angle ouvert

To measure the central corneal thickness (CCT) in Senegalese melanoderms with primary open angle glaucoma (POAG) and to determine its effect on visual impairment, intraocular pressure, optic nerve and perimetric damage. We studied retrospectively the records of patients followed for POAG between May and July 2012. We recorded CCT measured by ultrasonic pachymetry and results of the first clinical examinations, including best-corrected visual acuity (CVA), intraocular pressure (IOP) by Goldmann tonometry, cup-to-disc ratio (C/D), and visual fields by automated perimetry according to the classification of Hodapp. Two hundred and thirty-four eyes of 117 patients were enrolled. Mean age was 56.53 ± 11.29 years and gender ratio was 2.77. Mean CCT was 525.40 ± 39.63 μm for all eyes, right and left (P=0.734). Women had a mean CCT of 521.20 ± 36.20 μm and men 526.91 ± 40.79 μm (P=0.332). Corneas were thinner in patients over 50 years (P=0.0047), in eyes having a CVA<3/10 (P=0.01) or a C/D ≥ 0.8 (P=0.043). CCT had no correlation with frequency of ocular hypertension (P=0.16) or advanced visual field defect (P=0.33). CCT of glaucomatous Senegalese is independent of laterality and sex, but decreased with age. A thin cornea is a risk for visual loss and optic cup enlargement, thus the importance of systematic measurement of CCT.

Applanation tonometry: a comparison of the Perkins handheld and Goldmann slit lamp-mounted methods

PurposeTo compare intraocular pressure (IOP) measurements, taken using Perkins applanation tonometry (PAT) and Goldmann applanation tonometry (GAT).Methods100 eyes of 100 patients underwent Perkins and Goldmann applanation tonometry, with a randomized order of modality, performed by a masked observer. The right eye was measured, for all subjects, and the data used in statistical analysis. The comparability of results given by the two instruments was evaluated using the Bland–Altman method.ResultsIOP measurements for 100 eyes were obtained (range: 10–44 mmHg). The mean GAT reading was 21.63 mmHg, with standard deviation (SD) 5.69 mmHg. The mean PAT reading was 21.40 mmHg, with SD 5.67 mmHg. The mean difference between readings from Goldmann versus Perkins tonometry was 0.22 mmHg (SD: 0.44 mmHg). The limits of agreement were calculated to be −0.64–+1.08 mmHg (1.96 SD either side of the bias).ConclusionThe Perkins applanation tonometer yields IOP measurements that are closely comparable with GAT. Therefore, PAT may be used in routine clinical practice, as part of the implementation of national guidelines, or preferred practice patterns, for glaucoma and ocular hypertension.

Sensory Stimulation for Lowering Intraocular Pressure, Improving Blood Flow to the Optic Nerve and Neuroprotection in Primary Open-Angle Glaucoma

Primary open-angle glaucoma is a group of optic neuropathies that can lead to irreversible blindness. Sensory stimulation in the form of acupuncture or ear acupressure may contribute to protecting patients from blindness when used as a complementary method to orthodox treatment in the form of drops, laser or surgery. The objective of this article is to provide a narrative overview of the available literature up to July 2012. It summarises reported evidence on the potential beneficial effects of sensory stimulation for glaucoma. Sensory stimulation appears to significantly enhance the pressure-lowering effect of orthodox treatments. Studies suggest that it may also improve blood flow to the eye and optic nerve head. Furthermore, it may play a role in neuroprotection through regulating nerve growth factor and brain-derived neurotrophic factor and their receptors, thereby encouraging the survival pathway in contrast to the pathway to apoptosis. Blood flow and neuroprotection are areas that are not directly influenced by orthodox treatment modalities. Numerous different treatment protocols were used to investigate the effect of sensory stimulation on intraocular pressure, blood flow or neuroprotection of the retina and optic nerve in the animal model and human pilot studies. Objective outcomes were reported to have been evaluated with Goldmann tonometry, Doppler ultrasound techniques and electrophysiology (pattern electroretinography, visually evoked potentials), and supported with histological studies in the animal model. Taken together, reported evidence from these studies strongly suggests that sensory stimulation is worthy of further research.

Anterior Segment Changes After Pilocarpine and Laser Iridotomy for Primary Angle-Closure Suspects With Scheimpflug Photography

To assess changes in Scheimpflug-based measurements of the anterior segment after pilocarpine administration and prophylactic laser peripheral iridotomy in narrow anterior chamber angles. Thirty-seven eyes in 37 patients with occludable angles were included in this prospective interventional case series. Primary angle-closure suspects (iridotrabecular contact in 3 quadrants or more) were enrolled. Patient evaluation included indentation gonioscopy, Goldmann tonometry, and optic nerve examination. The mean of 3 consecutive Pentacam measurements was taken at baseline, 45 minutes after 2% pilocarpine administration, and 1 month after laser peripheral iridotomy (LPI). Anterior chamber angle (ACA), anterior chamber volume (ACV), anterior chamber depth (ACD), pupil diameter, central corneal thickness, and intraocular pressure were measured. ACV increased significantly after LPI (from a mean ± standard error of 94.6 ± 3.6 mm(3) to 108.8 ± 3.4 mm(3), P<0.001), as did the ACA (26.7 ± 0.9 degrees to 28.2 ± 0.8 degrees, P<0.001). Central corneal thickness decreased significantly after LPI (558.1 ± 5.3 μm to 552.6 ± 5.7 μm, P=0.018). Central ACD increased slightly after LPI, but this was not statistically significant (2.13 ± 0.05 mm to 2.15 ± 0.05 mm, P=0.109). Pupil diameter and intraocular pressure also did not change significantly after LPI. After pilocarpine, the ACV decreased significantly (by 4.3 ± 1.3 mm(3), P=0.009), as did the central ACD (by 0.1 ±0.02 mm, P<0.001) and the pupil diameter (by 0.74 ± 0.06 mm, P<0.001). Scheimpflug photography demonstrates significant anterior segment changes after pilocarpine and after LPI in primary angle-closure suspects.

Prevalência de ametropias e oftalmopatias no quilombo São José da Serra - Valença - RJ

OBJETIVO: Determinar a prevalencia das ametropias e oftalmopatias na populacao do Quilombo Sao Jose da Serra - Valenca - RJ. METODOS: Foram examinados 92 individuos de uma populacao de 102 pessoas da comunidade Quilombola em Sao Jose da Serra. Todos foram submetidos a avaliacao oftalmologica completa, incluindo anamnese, ectoscopia ocular, medida da acuidade visual, teste de estereopsia, reflexo vermelho, cobertura monocular, Hirschberg, refracao objetiva, subjetiva, biomicroscopia, tonometria de aplanacao de GoldmannR, tonometria de sopro e fundoscopia direta ou binocular indireta usando lente de 20D. RESULTADOS: Foram examinados cerca de 90,19% da populacao quilombola, sendo 61,95% do sexo feminino e 38,04% do sexo masculino. A idade variou de 6 meses a 89 anos. Foram encontrados ametropias com necessidade de correcao optica em 23,91% dos individuos sendo mais frequente a presbiopia associada a hipermetropia, miopia e/ou astigmatismo com prevalencia de 59,09% dos individuos examinados, seguido da presbiopia isolada em 22,72%, do astigmatismo hipermetropico em 13,63% e do astigmatismo miopico em 4,54% dos examinados. Em relacao as oftalmopatias encontraram-se catarata senil em 7,61%, ambliopia refracional em 6,52%, atrofia do epitelio pigmentar da retina e atrofia peripapilar em 2,17%, glaucoma em 1,09%, pterigio em 1,09%, retinocoroidite por toxoplasmose em 1,09% e hipopigmentacao retiniana (albinismo ocular) em 1,09%. CONCLUSAO: A prevalencia das ametropias e doencas oculares no Quilombo Sao Jose da Serra foi de 23,9%(22/92) e 20,6%(19/92), respectivamente.

Clinical Use of a New Position-independent Rebound Tonometer

To compare intraocular pressure (IOP) measurements obtained by rebound tonometry (Icare PRO tonometer), applanation tonometry (Goldmann and Perkins tonometry), and dynamic contour tonometry in the upright and the supine positions, and to investigate the influence of axial length and central corneal thickness. Ninety-nine right eyes of 99 patients with glaucoma or suspect for glaucoma, admitted to our department between November 2010 and January 2011 to obtain an IOP profile including supine measurements, were included in our study. IOP measurements were obtained in an upright position using an Icare PRO rebound (RTPRO), a Goldmann applanation (GAT), and a Pascal dynamic contour tonometer (DCT). In the supine position, IOP measurements were taken using the RTPRO and a Perkins hand-held applanation tonometer (PAT). The means and SDs for all tonometers were compared. Agreement between the tonometers was calculated using the Bland-Altman method. The mean IOPs obtained in the upright position were 17.7 ± 8.0 mm Hg (RTPRO), 17.6 ± 7.8 mm Hg (GAT), and 19.9 ± 6.6 mm Hg (DCT). Correlation analysis of these data indicated a good correlation between IOP readings obtained using RTPRO and GAT (r=0.951; P<0.001), and RTPRO and DCT (r=0.897; P<0.001). Bland-Altman analysis revealed mean differences (bias) between RTPRO and GAT, and between RTPRO and DCT of 0.1 mm Hg and -1.8 mm Hg, with 95% limits of agreement of -3.6 to 3.8 mm Hg and -7.3 to 3.6 mm Hg, respectively. In the supine position, the mean IOPs were 19.2 ± 6.4 mm Hg using the RTPRO and 19.6 ± 6.2 mm Hg using the PAT. Measurements obtained with the RTPRO, either in the upright or in the supine position, show good correlation and agreement with those provided by applanation and dynamic contour tonometry. The study was registered with the DRKS (German Clinical Trials Register; http://www.germanctr.de; DRKS00000581).

Corneal biomechanical properties: Precision and influence on tonometry

To assess the precision and reproducibility of the corneal biomechanical parameters, and their relationships with the intraocular pressure (IOP) measured with the Goldmann tonometer and a noncontact tonometer. Readings for biomechanical properties and for IOP measured with the Goldmann and noncontact tonometers, were taken on one randomly selected eye of 106 normal subjects, on each one of two measurement sessions. Measurements with the ocular response analyzer (ORA) and the noncontact tonometer were randomized, followed by the measurement of central corneal thickness and with the Goldmann tonometer. Repeatability coefficients for CCT, corneal hysteresis (CH) and corneal resistance factor (CRF) in Session 1 were ± 0.01 μm, ± 3.05 mmHg and ± 2.62 mmHg, respectively. The mean CCT, CH, CRF, Goldmann and noncontact tonometry did not vary significantly between sessions. Reproducibility coefficients for CCT, CH and CRF were ± 0.02 μm, ± 2.19 mmHg and ± 1.97 mmHg, respectively. Univariate regression analysis showed that CCT, CH and CRF significantly (P<0.0001) correlated with the IOP measured with the Goldmann and noncontact tonometers (and with the differences between tonometers) in Session 1. There were no significant correlations with the differences between tonometers in Session 2. Multivariate analysis revealed a minimal effect of CCT on Goldmann measurements but a significant effect on those of the noncontact tonometer. Measurement of the biomechanical properties of the cornea, using the ORA, are repeatable and reproducible, affect Goldmann tonometry less than noncontact tonometry, and have a minimal influence on the difference in measured intraocular pressure between tonometers.

Intraocular Pressure Measured With Goldmann, Noncontact, Schiøtz, and Dynamic Contour Tonometry After DSEK

To compare intraocular pressure (IOP) measurements with various tonometers after Descemet stripping with endothelial keratoplasty (DSEK) and to measure the change in IOP during the follow-up period. A total of 28 eyes of 28 patients having undergone DSEK for bullous keratopathy by a single surgeon from June 2008 to November 2011 were enrolled in this study. IOP values, which were measured with Goldmann applanation tonometry (GAT), noncontact tonometry (NCT), Schiøtz indentation tonometry (SIT), and dynamic contour tonometry, and central corneal thickness values were reviewed and analyzed up to 3 years after DSEK (range, 1 months-3 years). Different tonometers measured the IOP after DSEK differently. NCT showed the lowest IOP values, although GAT and NCT showed the smallest intertonometry difference. SIT showed extreme variation in IOP measurements. The dynamic contour tonometry values were higher than those of NCT or GAT. Central corneal thickness did not correlate with any of the IOP measurements. Only 2 episodes of IOP elevation greater than 30 mm Hg were detected. IOP measured with NCT or GAT may be lower than the real IOP after DSEK. SIT is not a reliable tonometry measurement after DSEK. Additional IOP measurements using different methods and consideration of other clinical signs may be the best method for ocular evaluation after DSEK.

Evidence of lower macular pigment optical density in chronic open angle glaucoma

Background/aimsMacular pigment (MP) plays an important role in visual function and in the protection of the retina from oxidative damage. It is not known whether glaucoma, a progressive neurodegenerative disease...

Twenty-four hour efficacy with preservative free tafluprost compared with latanoprost in patients with primary open angle glaucoma or ocular hypertension

AimTo compare 24 h intraocular pressure (IOP) control obtained with preservative free (PF) tafluprost 0.0015% versus branded preservative containing latanoprost 0.005% administered as first choice monotherapy in patients with primary...

Intravitreal Dexamethasone Implant for the Treatment of Macular Edema after Retinal Vein Occlusion in a Clinical Setting

To study the efficacy and safety of a new intravitreal implant (sustained release of dexamethasone, Ozurdex®) recently approved in Switzerland for the treatment of macular edema secondary to retinal vein occlusion in a clinical setting. Prospective non-consecutive study of patients with macular edema secondary to central retinal vein occlusion or branch retinal vein occlusion treated with implant of dexamethasone 0.7 mg. Follow-up visits were performed at day 1, week 1 and monthly thereafter. ETDRS best corrected visual acuity, Goldmann tonometry and macular thickness on SD-OCT were registered. Retreatment was carried out on a pro re nata basis starting from month 3. Fifteen eyes of 15 patients were included (8 branch retinal vein occlusions, 7 central retinal vein occlusions). 33% of the patients achieved 3 lines or more of vision gain. The central retinal vein occlusion subgroup showed a mean decline in visual acuity at month 3. A reduction of 36% of macular edema was already observed at day 1. All maculae were dry at month 1. The mean time of recurrence of macular edema for both groups was 4.6 months. A similar reduction of macular edema was obtained after a second implantation. An intraocular pressure increase of ≥ 20% was observed after the first implantation in 53% of patients. Our study showed efficacy and safety of intravitreal dexamethasone implant in the treatment of macular edema due to retinal vein occlusion. Anatomical efficacy was observed at day 1 but seems to have shorter effect than previously published data. No serious side effects were observed.

Manchester iStent study: early results from a prospective UK case series

To evaluate the 6-month efficacy and safety of the iStent microtrabecular bypass stent in patients with open-angle glaucoma. A prospective, uncontrolled, interventional case series. Forty-four eyes with open-angle glaucoma were reported. All subjects underwent ab interno implantation of a single iStent together with (n = 40) or without (n = 4) cataract surgery. Patients were assessed at postoperative week 1, months 1 and 3, and quarterly, thereafter. Data collected included visual acuity, intraocular pressure measurement using Goldmann tonometry, number of glaucoma medications, and number and type of complications. The mean age of the sample was 76.8 years. The mean duration since glaucoma diagnosis was 5.3 years (standard deviation 2.9 years). The mean visual acuity was 0.53 logMAR at baseline that improved to 0.23 at 6 months postoperatively. The mean baseline intraocular pressure was 21.1 mmHg, and this decreased significantly to 16.7 mmHg at 6 months (P < 0.01). The mean number of drops prescribed preoperatively was 2.3, which decreased to 0.6 at 6 months (P < 0.01). Sixty-six per cent of patients were drop-free at 6 months. One patient developed an hyphaema following surgery; no other adverse events were recorded. The iStent proved to be a safe and effective treatment for patients with open-angle glaucoma over our 6-month follow up period. Insertion resulted in a significant decrease in intraocular pressure as well as the number of topical antiglaucoma medications required for adequate intraocular pressure control.

Correction Factors for Goldmann Tonometry

The purpose of the study was to evaluate the in vitro accuracy of correction factors in decreasing the error in the intraocular pressure (IOP) measurements obtained using the Goldmann Applanation Tonometer (GAT). Nineteen donor corneas, from individuals aged between 57 and 99 years (mean 75.7 years, standard deviation±11.4 years) were subjected to posterior pressure simulating in vivo true IOP (IOPT) using an inflation test rig. Central corneal thickness and corneal curvature were measured. The posterior pressure was set at 25 different pressure levels between 5 and 45 mm Hg and IOP was measured using the GAT. Five different correction equations were applied to the IOP measurements obtained using the GAT to determine corrected IOP. The multiparameter correction equations applied were derived by Elsheikh, Ehlers, Chihara, Shimmyo et al, and Orssengo and Pye. The differences between IOPT and the IOP measured using the GAT were recorded as uncorrected errors, whereas the differences between IOPT and each of the corrected IOP were the tonometry errors after correction. The mean and standard deviation of error in tonometry before correction was +2.25±0.62 mm Hg. The mean errors in tonometry after correction using the Elsheikh and Chihara equations were +0.78±0.62 and +1.08±0.61 mm Hg, respectively. The mean errors in tonometry for the Ehlers, Shimmyo et al, and Orssengo and Pye equations were negative, indicating an overcorrection; the values were -0.75±2.28, -1.27±1.85, and -0.77±1.83 mm Hg, respectively. The Elsheikh and the Chihara et al's equations considerably decreased error in IOP measurements obtained by the GAT when compared with IOPT and were more consistent than other correction equations. The 2 equations may be of clinical utility in obtaining estimates of IOPT.

Sinnhaftigkeit von Tages-/Nacht-Augeninnendruckmessungen über 48 h

Diurnal intraocular pressure (IOP) measurements are recommended in cases of visual field deterioration in glaucoma patients. In this study the rationale of 24h versus 48h IOP measurements was investigated. Mean IOP and maximum IOP values were obtained in 80 patients over a period of 48h. The IOP measurements (Goldmann tonometry) of day 1 and 2 (taken every 4h) were compared. To reduce interindividual and intraindividual differences of measurements the statistical calculation took a tolerance level of ± 2mmHg and ± 1mmHg into account. Maximum IOP measurements were found to differ between 37.5% and 65.0% respectively for right eyes and 28.8% and 47.5% respectively for left eyes depending on the measurement tolerance (±2mmHg or ±1mmHg) between day 1 and day 2. Mean IOP values were found to differ by 25% and 51.3% respectively for right eyes and 26.3% and 46.3% respectively for left eyes (± 2 or ± 1mmHg in) between day 1 and day 2. A time-related clustering of extreme deviations could not be found but the maximum values from all patients were found to be roughly equally distributed over daytime and nighttime hours. Both maximum IOP and mean IOP measurements were found to differ by at least ± 2 or ± 1mmHg between day 1 and 2 at a significant percentage and the maximum values did not peak at a predictable time point during the 48h. Therefore, 48h IOP measurements appear to be more reliable than 24h measurements.