Measurement of the difference in intraocular pressure between the sitting and lying body positions in healthy subjects: direct comparison of the Icare Pro with the Goldmann applanation tonometer, Pneumatonometer and Tonopen XL

BACKGROUND

Change in intraocular pressure is known to occur with body posture. Previously, markedly different estimations of this change were reported. The Icare Pro (Icare; Tiolat Oy, Helsinki, Finland) is designed to measure intraocular pressure with the subject supine. We compared the measurement of postural change in intraocular pressure obtained with this and 3 other tonometers: Goldmann applanation tonometer (CSO, Firenze, Italy), Pneumatonometer (Model 30, Reichert, Depew, NY, USA) and the Tonopen XL (Reichert).

DESIGN

Prospective comparative study.

PARTICIPANTS

Twenty-one healthy subjects.

METHODS

Intraocular pressure was measured in random order with four tonometers, first sitting then after 10 min of lying.

MAIN OUTCOME MEASURES

Average postural intraocular pressure change (mmHg) and the 95% limits of agreement for measuring postural intraocular pressure change between tonometers.

RESULTS

Average postural intraocular pressure change (lying minus sitting, mmHg) was measured highest with the Goldmann applanation tonometer (4.1 ± 2.6) and Pneumatonometer (3.9 ± 2.1), significantly lower with the Tonopen (0.9 ± 1.7) and was negative with the Icare (-0.9 ± 3.3). The 95% limits of agreement for measuring postural intraocular pressure change between Goldmann applanation tonometer and Icare, Pneumatonometer and Tonopen were -3.2-13.3, -6.4-6.9 and -2.8-9.4 mmHg, respectively.

CONCLUSIONS

Postural change in intraocular pressure was measured similarly, on average, with Goldmann applanation tonometer and Pneumatonometer, and much lower with Tonopen and Icare Pro. There was poor interdevice agreement in measuring this parameter. We observed high intersubject variability, suggesting the clinical importance of this measurement in the diagnosis and management of glaucoma.

Blur-resistant perimetric stimuli

PURPOSE

To develop perimetric stimuli that are resistant to the effects of peripheral defocus.

METHODS

One eye each was tested on subjects free of eye disease. Experiment 1 assessed spatial frequency, testing 12 subjects at eccentricities from 2 to 7 degrees using blur levels from 0 to 3 diopters (D) for two (Gabor) stimuli (spatial SD, 0.5 degrees; spatial frequencies, 0.5 and 1.0 cycles per degree [cpd]). Experiment 2 assessed stimulus size, testing 12 subjects at eccentricities from 4 to 7 degrees using blur levels 0 to 6 D for two Gaussians with SD of 0.5 and 0.25 degrees and a 0.5-cpd Gabor with SD of 0.5 degrees. Experiment 3 tested 13 subjects at eccentricities from fixation to 27 degrees using blur levels 0 to 6 D for Gabor stimuli at 56 locations; the spatial frequency ranged from 0.14 to 0.50 cpd with location, and SD was scaled accordingly.

RESULTS

In experiment 1, blur by 3 D caused a small decline in log contrast sensitivity for the 0.5-cpd stimulus (mean ± SE, 0.09 ± 0.08 log units) and a larger (t = 7.7, p < 0.0001) decline for the 1.0-cpd stimulus (0.37 ± 0.13 log units). In experiment 2, blur by 6 D caused minimal decline for the larger Gaussian, by 0.17 ± 0.16 log units, and larger (t > 4.5, p < 0.001) declines for the smaller Gaussian (0.33 ± 0.16 log units) and the Gabor (0.36 ± 0.18 log units). In experiment 3, blur by 6 D caused declines by 0.27 ± 0.05 log units for eccentricities from 0 to 10 degrees, by 0.20 ± 0.04 log units for eccentricities from 10 to 20 degrees, and 0.13 ± 0.03 log units for eccentricities from 20 to 27 degrees.

CONCLUSIONS

Experiments 1 and 2 allowed us to design stimuli for experiment 3 that were resistant to effects of peripheral defocus.

Characterization of the thickness of different corneal zones in glaucoma: effect on dynamic contour, Goldmann and rebound tonometries

PURPOSE

To characterize five models of corneal thickness circular zoning in a sample of healthy controls and a sample of patients with primary open-angle glaucoma (POAG) and to determine their effect on Goldmann (GAT), dynamic contour (DCT) and rebound tonometers (RT).

METHODS

The study participants were 122 controls and 129 cases. Five corneal thickness zoning models (A, B, C, D and E) were constructed. The partitioning pattern consisted of a circle centred at the corneal apex and several concentric rings, until the limbus; the contours of each ring followed the geometry of the corneal contour of each participant. In Model A, the central circle was 1 mm in diameter and five concentric rings were established. Mean was obtained for each zone for both samples and compared between them using a t-test. The effect on the tonometers of central cornel thickness (CCT) and mean thickness of the zones generated was determined through several linear regression models (one per tonometer and per sample).

RESULTS

According to a t-test, cases and controls differ in zones I [mean difference (MD): 17.93 μm], V (MD: 25.52 μm) and VI (MD: 31.78 μm) of model A (higher values in the cases sample). RT was affected by CCT (controls: B = 0.089; cases: B = 0.081). DCT was affected by zone IV of model A (controls: B = -0.029; cases: B = -0.012). GAT was affected by CCT (controls: B = 0.043; cases: B = 0.025) and zone III of model A (controls: B = -0.045; cases: B = -0.033).

CONCLUSION

Our results highlight the importance of the thickness of other regions of the cornea different from its main centre in discriminating between healthy controls and patients with POAG and in IOP measurements made using DCT, GAT and RT.

Corneal involvement in uneventful cataract surgery: an in vivo confocal microscopy study

PURPOSE

To evaluate corneal subbasal layer changes after uneventful cataract surgery by means of in vivo confocal microscopy.

METHODS

This prospective study included 30 patients. Before surgery, and 1, 3, 6, 8 and 10 months after cataract surgery, all patients underwent a complete ophthalmological and confocal microscopy examination in the central and temporal corneal areas. Number of fibers, beading, tortuosity and reflectivity were analyzed.

RESULTS

Important changes were shown in the central cornea up to 3 months after surgery: a reduction in nerve fiber number (baseline: 4.4 ± 1.7; month 1: 1.2 ± 0.5, p < 0.0001; month 3: 2.5 ± 1.2, p < 0.005) and reflectivity (baseline: 3.6 ± 0.5; month 1: 1.4 ± 0.6, p < 0.0001; month 3: 1.9 ± 0.9, p < 0. 0001), and an increase in beading (baseline: 0.3 ± 0.5 beads/100 µm(2); month 1: 2.7 ± 0.6 beads/100 µm(2), p < 0.0001; month 3: 2.6 ± 0.5 beads/100 µm(2), p < 0. 0001). The confocal parameters completely progressively recovered thereafter (60% at 6 months, 87% at 8 and 10 months). The temporal plexus was absent at 1 month and fully recovered in all patients at month 8.

CONCLUSION

Uneventful cataract surgery induces relevant corneal modifications when inspected by means of confocal microscopy.

[Pulsar perimetry. A review and new results]

We present a review and update on Pulsar perimetry, which combines temporal frequency, contrast and spatial frequency stimuli. The effects of age, visual acuity, and learning on results are described. Data on threshold fluctuation, signal-to-noise ratio, and the possibility of reducing noise with filtering techniques are provided. We describe its dynamic range and the possibility of compensating for profound defects. Finally, we show the results obtained in normal patients and in those with ocular hypertension or initial glaucoma, as well as an analysis of glaucoma progression.

Screening for Patients with Mild Alzheimer Disease Using Frequency Doubling Technology Perimetry

We compared the visual field performances of patients with mild Alzheimer disease (AD) with normal subjects and detected visual field impairment attributable to the magnocellular pathway using frequency doubling technology-Matrix (FDT-Matrix). We recruited 43 patients with mild AD (mean age: 68.0 ± 7.2 years) and 33 controls who are visually and cognitively normal (mean age: 64.1 ± 6.4 years). All participants had at least two reliable FDT-Matrix 30-2 tests. Reliability indices, global indices (mean deviation and pattern standard deviation), and glaucoma hemifield test results were measured with FDT-Matrix. The mean test duration was significantly longer in patient group compared with controls (p = 0.002). Among the reliability indices, false negatives were higher in patient group than controls (p = 0.003). There were statistically significant differences in mean deviation and pattern standard deviation values (p < 0.0001 and p < 0.0001, respectively) and glaucoma hemifield test results (p < 0.001) between the patient and the control group. Our results imply that the pathogenesis of cognitive deterioration may not only be confined to the cortical area but also to the magnocellular pathway. We underline that FDT testing can be useful for the identification of early impairment and the follow-up of patients with AD.

Assessment of peripapillary retinal nerve fiber layer thickness using scanning laser polarimetry (GDx VCC) in normal Indian children

Purpose:

To obtain reference values of RNFL thickness in normal Indian children and to study the association of RNFL thickness with central corneal thickness(CCT) and axial length(AL).

Materials and Methods:

200 normal Indian children (mean age 8.6 ± 2.9 yrs) were examined on the GDxVCC. The inferior average (IA), superior average (SA), temporal-superior-nasal-inferior-temporal (TSNIT) average and nerve fiber index (NFI) values were recorded and compared between males and females as well as between the different age groups. The association of TSNIT average with AL and CCT was examined.

Results:

Values for the RNFL parameters were-SA: 64.9 ± 9.7, IA: 63.8 ± 8.8, TSNIT average: 53.5 ± 7.7 and NFI 21.5 ± 10.8. Superior, inferior and TSNIT averages did not differ significantly between males and females (P = 0.25, P = 0.19, P = 0.06 respectively; Mann-Whitney U test). No significant differences were found in TSNIT average across age groups. There was a statistically significant positive correlation between CCT and TSNIT average (r = 0.25, r² = 0.06, P < 0.001). The correlation TSNIT average and AL(r = −0.12; r² = 0.01) was not significant (P = 0.2).

Conclusion:

Reference values for RNFL parameters reported for Indian children are similar those reported in adults. There is a small correlation between central corneal thickness and RNFL as reflected in average TSNIT.

Comparison of IOPen rebound tonometer with Goldmann applanation tonometer at different IOP levels

AIM

To compare the accuracy of IOPen rebound tonometer with Goldmann applanation tonometer (GAT) in individuals with low, normal and high intraocular pressure (IOP) and to evaluate the effect of central corneal thickness (CCT) on IOP measurements.

METHODS

This cross-sectional study consisted of 159 participants. IOP of one eye of each subject was measured consecutively with IOPen and GAT. Then CCT was measured using an ultrasonic pachymeter. Based on GAT IOP readings, participants were divided into low, normal and high IOP groups. Correlation between tonometers and CCT was calculated by spearman's correlation coefficient. Agreement between tonometers was evaluated using Bland-Altman method.

RESULTS

Non-significant underestimation of IOP by IOPen was observed in low IOP group (Mean difference: 0.20mmHg; P=0.454) and also in normal IOP group (Mean difference: 0.56mmHg; P=0.065). However, IOPen significantly overestimated IOP in high IOP group (Mean difference: 1.06mmHg; P=0.038). The 95% limits of agreement (LoA) width between IOPen and GAT IOPs were 7.84, 8.57 and 14.27mmHg in low, normal and high IOP groups, respectively. Low IOP group had thinner corneas compared to high IOP group (P=0.034). IOP measurements taken by IOPen were not influenced by CCT (P=0.099) while poor correlation between CCT and GAT was found (R=0.17, P=0.032). Using receiver operating characteristic (ROC) curve, cutoff value of 18.75mmHg was determined for IOPen with sensitivity of 98.1 and specificity of 97.2%.

CONCLUSION

Accuracy of IOPen is comparable to GAT in patients with low or normal IOP but IOPen overestimates IOP at high IOP levels. CCT does not affect IOP readings with IOPen.

Postkeratoplasty Anterior and Posterior Corneal Surface Wavefront Analysis: Descemet's Stripping Automated Endothelial Keratoplasty versus Penetrating Keratoplasty

Purpose. To compare the higher-order aberrations (HOAs) due to the anterior and posterior corneal surfaces in patients that underwent either Descemet-stripping-automated-endothelial-keratoplasty (DSAEK) or penetrating keratoplasty (PK) for endothelial dysfunction and age-matched controls. Methods. This retrospective, observational, case series included 28 patients after PK, 30 patients after DSAEK, and 30 healthy controls. A Scheimpflug imaging system was used to assess the HOAs due to the anterior and posterior corneal surfaces at 4 mm and 6 mm optical zones. Total, 3rd and 4th order HOAs were considered. Intra- and intergroup differences were assessed using the Friedman and the Kruskal-Wallis tests, respectively; paired comparisons were performed using Duncan's multiple range test. Results. Total, 3rd and 4th order HOAs due to both corneal surfaces at 4 mm and 6 mm optical zones were significantly higher in the PK group, intermediate in the DSAEK group, and lower in controls (P < 0.05). The most important HOAs components in both PK and DSAEK groups were trefoil and coma from the anterior corneal surface (P < 0.05) and trefoil from the posterior corneal surface (P < 0.05). Conclusions. The optical quality of both corneal surfaces appeared significantly higher after DSAEK than after PK, which can increase the postoperative patient's quality of vision and satisfaction.

Comparison of the new rebound tonometer with Goldmann applanation tonometer in a clinical setting

PURPOSE

To evaluate the clinical usefulness of a new rebound tonometer, Icare(®) PRO (Icare PRO), by comparison with Goldmann applanation tonometry (GAT) in a study on patients with glaucoma.

METHODS

One hundred and seventy-two eyes of 86 subjects were enrolled in this study. All of the subjects were examined with an autorefractometer, Icare PRO, slit-lamp biomicroscope, GAT, ultrasound A-scan and pachymeter. Three intraocular pressure (IOP) measurements were obtained by Icare PRO and GAT. The intraobserver reliabilities were established by calculating the intraclass correlation coefficients. The Bland-Altman plot was used to compare the Icare PRO and GAT.

RESULTS

There was a good correlation between the IOP measurement by GAT and that by Icare PRO (r = 0.6995, p < 0.001). The intraclass correlation coefficients of Icare PRO and GAT were 0.778 and 0.955, respectively. The IOP differences between Icare PRO and GAT (mean: 1.92 mmHg; SD: 3.29 mmHg; 95% limit of agreement: -4.52 to 8.37 mmHg) did not vary over the wide range of central corneal thickness (p = 0.498), age (p = 0.248), axial length (p = 0.277) or spherical equivalent (p = 0.075).

CONCLUSIONS

Although IOP with Icare PRO was higher than that with GAT, especially at lower GAT IOP value, Icare PRO was found to be a reliable method and showed a good correlation with GAT. The IOP difference between Icare PRO and GAT was not affected by the central corneal thickness, age, axial length or spherical equivalent. Icare PRO can be expected not only to be a good screening tool but also to be a good substitute for GAT.

Inhalation anesthesia with sevoflurane during intravitreal bevacizumab injection in infants with retinopathy of prematurity

Bacground. To investigate the anesthetic management in premature infants with retinopathy of prematurity (ROP) treated with intravitreal bevacizumab (IVB) injections. Methods. A retrospective chart review was performed for the patients with ROP who had IVB injection. Clinical characteristics, demographic variables, anesthetic medications, operation techniques, time intervals, and complications were recorded. Results. Sixty-six eyes of 33 patients (23 males, 10 females) with type 1 ROP who were treated with IVB were included. A total of 66 anesthetic applications were performed. Mean gestational age at birth was 28.3 weeks (range 25–33). Mean birth weight was 1300 g (range 600–1850). Serious ocular and systemic complications were not observed in any infant. Conclusion. Inhalation anesthesia with sevoflurane during IVB treatment in premature infants with ROP may be appropriate for anesthetic management.

Adverse events and complications associated with intravitreal injection of anti-VEGF agents: a review of literature

Intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents is increasingly used for the treatment of a wide variety of retinal diseases, including age-related macular degeneration, diabetic retinopathy and retinal vascular occlusions, and retinopathy of prematurity. Despite encouraging results in halting the disease and improving the vision, intravitreal injection of anti-VEGF agents may be associated with systemic adverse events and devastating ocular complications. In this review, we provide an overview of safety data for intravitreal injection of common anti-VEGF agents.

Visual field loss in schizophrenia: evaluation of magnocellular pathway dysfunction in schizophrenic patients and their parents

Purpose:

We sought to evaluate the visual pathway deficits in schizophrenic patients, compared with their parents and healthy controls, using Matrix frequency doubling technology (FDT) perimetry. Matrix FDT is an ophthalmic test used to detect visual field loss.

Method:

A total of 13 patients, 13 parents, and 12 healthy controls were enrolled in the study. Participants were subjected to Matrix FDT perimetry in a single test session. We analyzed the mean deviation for each eye and used a generalized estimated equation to evaluate differences among the groups and correct the dependency between the eyes.

Results:

The global mean deviation (presented as the mean of both eyes) was significantly lower in the schizophrenic patients than in their parents or controls. Analysis of the general sensitivity of the fibers crossing the optic chiasm showed a difference between the groups (P = 0.006), indicating that the sensitivity of the fibers crossing the optic chiasm was lower than those which did not cross. But when we analyzed the specific groups, the difference between the fibers was not considerable. Comparison of the right and left hemispheres showed that general sensitivity was lower for the left hemisphere, but when we analyzed specific groups, the difference was not significant (P = 0.29).

Conclusion:

These findings are suggestive of a lower global sensitivity in schizophrenic patients and their parents compared with controls. This difference may be an endophenotype of schizophrenia. The present study adds to a growing body of research on early-stage visual processing deficits in schizophrenia.

Predictive value of 1 month retinal nerve fiber layer thinning for deficits at 6 months after acute optic neuritis

BACKGROUND

Retinal nerve fiber layer (RNFL) loss occurs with multiple sclerosis and after optic neuritis. Vision or RNFL changes at presentation of optic neuritis are not predictive of outcome, but vision loss at 1 month correlates with vision deficits at 6 months. We hypothesized that RFNL thinning at 1 month would predict RNFL loss at 6 months.

METHODS

We prospectively studied the RNFL by optical coherence tomography (OCT) and scanning laser polarimetry (SLP), and determined the threshold field mean deviation, in 25 subjects with acute optic neuritis over a 6-month period. RNFL values, including the amount of thinning at 1-month, were correlated with 6-month outcome.

RESULTS

Baseline visual performance and RNFL values were similar for eyes grouped by 1 month RNFL thinning. Eyes with 1 month RNFL thinning had greater and significant RNFL thinning at 6 months, for all quadrants by OCT and for the nasal and inferior quadrants by SLP. RNFL thinning by OCT and SLP at 1 month correlated with 6-month OCT (r = 0.58; p = 0.006) and SLP (r = 0.59; p = 0.002) RNFL thinning, respectively.

CONCLUSION

Early RNFL loss at 1 month was predictive of the RNFL thinning at 6 months, which corroborated the importance of the 1-month time point for predicting the outcome of an optic neuritis attack.

Color Doppler imaging analysis of retrobulbar blood flow velocities in primary open-angle glaucomatous eyes: a meta-analysis

Background

To analyze the diagnostic value of color Doppler imaging (CDI) of blood flow in the retrobulbar vessels of eyes with primary open-angle glaucoma (POAG).

Methods

Pertinent publications were retrieved from the Cochrane Central Register of Controlled Trials, PubMed and the ISI Web of Knowledge up to October 2012. Changes in peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) of the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary artery (SPCA) of POAG eyes and normal controls were evaluated by CDI. Subgroup analyses were conducted according to whether patients received IOP-lowering drugs treatment and were defined as treated and untreated.

Results

PSV and EDV were statistically significantly reduced in the OA of POAG eyes (P = 0.0002; P<0.00001; respectively), with significant heterogeneity (P_{heterogeneity}<0.00001, I² = 94%; P_{heterogeneity}<0.00001, I² = 85%; respectively). Similar results were demonstrated for the CRA (P<0.00001; respectively) and SPCA (P = 0.005; P<0.00001; respectively), with significant heterogeneities for both the CRA (P_{heterogeneity}<0.00001, I² = 81%; P_{heterogeneity}<0.00001, I² = 98%; respectively) and the SPCA (P_{heterogeneity}<0.00001, I² = 96%; P_{heterogeneity}<0.00001, I² = 93%; respectively). Significant increases in RI were found in all retrobulbar vessels (P<0.00001; respectively), with significant heterogeneities (P_{heterogeneity}<0.00001, I² = 95%; P_{heterogeneity}<0.00001, I² = 94%; P_{heterogeneity}<0.00001, I² = 97%; respectively).

Conclusions

This meta-analysis suggests that CDI is a potential diagnostic tool for POAG.

Comparison of Goldmann Tonometry and Dynamic Contour Tonometry in Normal and Descemet Stripping Endothelial Keratoplasty Eyes

PURPOSE

This study aimed to compare intraocular pressures (IOP) measured by dynamic contour tonometry (DCT) with Goldmann tonometry (GAT) in Descemet stripping endothelial keratoplasty (DSEK) eyes. The agreeability between the 2 established methods and their relation to central corneal thickness (CCT) was also studied.

DESIGN

A comparative case series.

METHODS

Forty-six eyes of DSEK were enrolled at least 3 months after the procedure. Thirty-five other eyes of the same patient cohort served as control. Intraocular pressures were measured by DCT and GAT by 2 different examiners in a randomized manner. Central corneal thickness was measured by ultrasonic pachymetry. Statistical analysis was used for the calculation of means, SD, coefficient of determination, linear regression, and Bland and Altman plot. Statistical significance was considered as P < 0.05.

RESULTS

Mean CCT was 624.49 μm and 518.41 μm in DSEK and control eyes, respectively. Mean IOP by GAT and DCT, respectively, was 19.4 and 21.5 mm Hg in DSEK eyes and 15.12 and 17.6 mm Hg in controls. Descemet stripping endothelial keratoplasty eyes showed universally higher IOP by either method in comparison with normal controls. Dynamic contour tonometry reading was significantly higher than GAT in both (P < 0.05) groups. The correlation between IOP and CCT was not significant in DSEK eyes (P > 0.05).

CONCLUSIONS

A higher baseline IOP is to be expected in DSEK eyes, which is independent of corneal thickness. Both GAT and DCT can be used as a standard method to measure IOP in DSEK eyes, but their readings cannot be used interchangeably.

Rapid assessment of neurovisual integrity using multiple rarebits

OBJECTIVE

Rapid assessments of vision commonly rely on visual acuity testing alone. Although well suited for uncovering optical defects, visual acuity tests may fail to detect dysfunction of the neural substrate. There is a need for a rapid companion test sensitive to neural damage.

DESIGN

Evaluation of diagnostic tests.

PARTICIPANTS AND CONTROLS

Forty-seven patients with optic nerve or visual pathway lesions of low to moderate severities and 30 normal subjects.

METHODS

A new computer-based quick test of neurovisual integrity was developed using segmented digits defined by rarebits, that is, receptive field-size bright dots briefly presented on a dark background.

MAIN OUTCOME MEASURES

The test variable was the number of rarebits per segment; digit size was fixed. The test task was to call out verbally all digits that were seen during an 8-second presentation sequence. Test outcomes were contrasted with the results of an optotype acuity test and automated perimetry.

RESULTS

All subjects easily grasped the test task. The normal subjects read, on average, 5.6 (± 0.5 standard deviation) of the 6 digits contained in the test sequence, whereas the patients averaged 3.3 ± 1.8 digits. The numbers of digits read correlated modestly with the acuity and perimetry results. Analysis of receiver operating characteristic curves indicated that the multiple rarebit test provided the best discrimination.

CONCLUSIONS

The multiple rarebit test seemed to be highly capable of detecting neurovisual dysfunction. Its simplicity and uniquely short duration indicate a useful role in screening settings. The test is available free on the Internet.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Test retest variability of TonoPen AVIA

The study was conducted to evaluate the intra-session repeatability of Tonopen AVIA (TPA). 180 eyes of 180 patients (50 eyes with glaucoma, 130 eyes of controls) were recruited for this observational study. The mean age of patients enrolled in the study was 43.9 ± 16.7 yrs (84 males, 96 females). Mean IOP recorded with Tonopen AVIA was 19.5 ± 9.5 mmHg, 19.4 ± 9.6 mmHg and 19.3 ± 9.2 mmHg, respectively in the first, second and third instances (P = 0.656). The intraclass correlation coefficient (ICC) ranged from 0.996 (95% CI: 0.956 - 0.998) for glaucoma subjects to 0.958 (95% CI: 0.934 - 0.975) for controls. The coefficient of variation in the study population ranged from 3.47% (glaucoma patients) to 8.10% (healthy controls), being 6.07% overall. The coefficient of repeatability varied between 2.96 (glaucoma patients), 3.35 (healthy controls) to 3.24 (overall). Thus, the Tonopen Avia shows good intrasessional repeatability of IOP in both glaucomatous patients and healthy subjects.

Learning effect and test-retest variability of pulsar perimetry

PURPOSE

To assess Pulsar Perimetry learning effect and test-retest variability (TRV) in normal (NORM), ocular hypertension (OHT), glaucomatous optic neuropathy (GON), and primary open-angle glaucoma (POAG) eyes.

METHODS

This multicenter prospective study included 43 NORM, 38 OHT, 33 GON, and 36 POAG patients. All patients underwent standard automated perimetry and Pulsar Contrast Perimetry using white stimuli modulated in phase and counterphase at 30 Hz (CP-T30W test). The learning effect and TRV for Pulsar Perimetry were assessed for 3 consecutive visual fields (VFs). The learning effect were evaluated by comparing results from the first session with the other 2. TRV was assessed by calculating the mean of the differences (in absolute value) between retests for each combination of single tests. TRV was calculated for Mean Sensitivity, Mean Defect, and single Mean Sensitivity for each 66 test locations. Influence of age, VF eccentricity, and loss severity on TRV were assessed using linear regression analysis and analysis of variance.

RESULTS

The learning effect was not significant in any group (analysis of variance, P>0.05). TRV for Mean Sensitivity and Mean Defect was significantly lower in NORM and OHT (0.6 ± 0.5 spatial resolution contrast units) than in GON and POAG (0.9 ± 0.5 and 1.0 ± 0.8 spatial resolution contrast units, respectively) (Kruskal-Wallis test, P=0.04); however, the differences in NORM among age groups was not significant (Kruskal-Wallis test, P>0.05). Slight significant differences were found for the single Mean Sensitivity TRV among single locations (Duncan test, P<0.05). For POAG, TRV significantly increased with decreasing Mean Sensitivity and increasing Mean Defect (linear regression analysis, P<0.01).

CONCLUSIONS

The Pulsar Perimetry CP-T30W test did not show significant learning effect in patients with standard automated perimetry experience. TRV for global indices was generally low, and was not related to patient age; it was only slightly affected by VF defect eccentricity, and significantly influenced by VF loss severity.

Oculus-Spark perimetry compared with 3 procedures of glaucoma morphologic analysis (GDx, HRT, and OCT)

PURPOSE

To compare diagnostic capabilities and agreement between Oculus-Spark perimetry and 3 procedures of glaucoma morphologic analysis.

METHODS

A total of 102 normal eyes and 104 consecutive eyes with suspected or confirmed glaucoma (1 eye per subject) were analyzed in a prospective observational case-control study, using Spark strategy (Oculus Easyfield Perimeter), Heidelberg retinal tomograph (HRT), Zeiss laser polarimetry (GDx), and Cirrus optical coherence tomography (OCT).

RESULTS

Spark first phase lasted 37 seconds and all 4 phases 2:34 minutes. Specificities and sensitivities were as follows: Spark mean deviation (MD) first phase (95.1%, 85.6%), MD second and final phases (95.1%, 86.5%), GDx-nerve fiber indicator (95.1%, 57.4%), HRT-Reinhard Burk discriminant function (95.1%, 52.9%), HRT glaucoma probability score (95.1%, 71.2%), Cirrus OCT vertical cup/disc ratio (96.1%, 85.6%), and Cirrus OCT retinal nerve fiber layer thickness (95.1%, 68.0%). Diagnostic agreement between second and final Spark MD phases was kappa=0.92; between phase 1 Spark/MD and Cirrus OCT/vertical C/D ratio was kappa=0.78. Agreements between the 2 Cirrus OCT indices was kappa=0.69 and between the 2 HRT indices was kappa=0.559. The correlation coefficient between second and final MD and PSD was 0.99, and 0.98 between the number of scotomatous points. There was high concordance in scotoma position in both phases (kappa=0.86). The linear correlation coefficients between the morphologic indices were 0.48-0.78, and between morphologic and functional indices 0.51-0.76. Correlation coefficients comparing morphologic and functional indices were similar in the first and the last phase (p>0.05 in all cases).

CONCLUSIONS

Spark perimetry appears to show useful sensitivity and specificity, even in the first phase, and good agreement with the morphology.

Comparison of handheld rebound tonometry with Goldmann applanation tonometry in children with glaucoma: a cohort study

OBJECTIVE

To test agreement of two methods to measure intraocular pressure (IOP): rebound tonometry (RBT) and gold standard Goldmann applanation tonometry (GAT) in children with glaucoma.

DESIGN

Observational prospective cohort study.

SETTING

Tertiary paediatric glaucoma clinic at a single centre.

PARTICIPANTS

102 individuals attending a paediatric glaucoma clinic, mean (SD) age 11.85 (3.17), of whom 53 were male.

PRIMARY AND SECONDARY OUTCOME MEASURES

Intraocular pressure, central corneal thickness, child preference for measurement method.

RESULTS

Limits of agreement for intraobserver and interobserver were, respectively, (-2.71, 2.98) mm Hg and (-5.75, 5.97) mm Hg. RBT frequently gave higher readings than GAT and the magnitude of disagreement depend on the level of IOP being assessed. Differences of 10 mm Hg were not uncommon. RBT was the preferred method for 70% of children.

CONCLUSIONS

There is poor agreement between RBT and GAT in children with glaucoma. RBT frequently and significantly overestimates IOP. However, 'normal' RBT readings are likely to be accurate and may spare children an examination under anaesthesia (EUA). High RBT readings should prompt the practitioner to use another standard method of IOP measurement if possible, or consider the RBT measurement in the context of clinical findings before referring the child to a specialist clinic or considering EUA.

Intraocular Pressure rise after Anti-VEGF Treatment: Prevalence, Possible Mechanisms and Correlations

Intraocular pressure (IOP) rise after anti-vascular endothelial growth factor (VEGF) treatment for neovascular age-related macular degeneration (AMD) can be either short-term or long-term and may require medical intervention. Short-term IOP spikes are a fairly common and well recognized complication of anti-VEGF injections. Long-term IOP rise is less well-understood and disputed as a complication by some authors. We try to review current literature on the subject and especially studies focused on the prevalence of this complication, speculate on possible mechanisms of IOP rise and discuss correlations of long-term IOP rise with the nature of the injected agent, average number of injections, previous glaucoma history and other factors. How to cite this article: Kampougeris G, Spyropoulos D, Mitropoulou A. Intraocular Pressure rise after Anti-VEGF Treatment: Prevalence, Possible Mechanisms and Correlations. J Current Glau Prac 2013;7(1):19-24.

Intraocular pressure in a cohort of healthy eastern European schoolchildren: variations in method and corneal thickness

Background

Intraocular pressure (IOP) in the developing eye of a child is not always easy to measure and there is no technique that is known to be the most accurate for the young eye. Measurements are needed on many cohorts of children with different tonometers to determine how the values correlate between instruments, whether corneal parameters affect readings and whether correlations between age and IOP values can be discerned. The aim of this study was to undertake a comparative analysis of three different tonometers on a group of healthy children to see whether differences exist and whether these may be related to central corneal thickness and/or radius of curvature. In addition, the study adds to the relatively small body of literature on IOP in the growing eye which will collectively allow trends to be identified and ultimately norms to be established.

Methods

IOP was measured on 115 eyes in a group of Polish children, aged between 5–17 years (mean ± standard deviation [SD] 11.3 ± 3.0 years) using three different tonometers: non-contact (NCT), the ICare and Goldmann applanation (GAT). Readings obtained were compared between instruments and with central corneal thickness and radius of curvature.

Results

The ICare tonometer provided statistically higher IOP values (16.9 ± 3.4 mmHg) than the GAT (14.7 ± 2.9 mmHg) regardless of corneal thickness and whether or not a correction factor was applied. A correlation was found between central corneal thickness (CCT) and IOP values obtained with all three tonometers but only the IOP values detected with the ICare tonometer showed a statistically significant correlation with radius of curvature (p < 0.004). No correlations with age or gender were found for IOP values measured with any of the instruments.

Conclusions

IOP measurements on children vary significantly between instruments and correlations are affected by the corneal thickness. Further studies on children are needed to determine which instrument is most appropriate and to derive a normative IOP scale for the growing eye.

The retinal nerve fibre layer thickness in glaucomatous hydrophthalmic eyes assessed by scanning laser polarimetry with variable corneal compensation in comparison with age-matched healthy children

PURPOSE

To compare the thickness of the retinal nerve fibre layer (RNFL) in hydrophthalmic glaucomatous eyes in children with age-matched healthy controls using scanning laser polarimetry with variable corneal compensation (GDxVCC).

METHODS

Twenty hydrophthalmic eyes of 20 patients with the mean age of 10.64 ± 3.02 years being treated for congenital or infantile glaucoma were included in the analysis. Evaluation of RNFL thickness measured by GDxVCC in standard Temporal-Superior-Nasal-Inferior-Temporal (TSNIT) parameters was performed. The results were compared to TSNIT values of an age-matched control group of 120 healthy children published recently as referential values. The correlation between horizontal corneal diameter and RNFL thickness in hydrophthalmic eyes was also investigated.

RESULTS

The mean ± SD values in TSNIT Average, Superior Average, Inferior Average and TSNIT SD in hydrophthalmic eyes were 52.3 ± 11.4, 59.7 ± 17.1, 62.0 ± 15.6 and 20.0 ± 7.8 μm, respectively. All these values were significantly lower compared to referential TSNIT parameters of age-matched healthy eyes (p = 0.021, p = 0.001, p = 0.003 and p = 0.018, respectively). A substantial number of hydrophthalmic eyes laid below the level of 5% probability of normality in respective TSNIT parameters: 30% of the eyes in TSNIT average, 50% of the eyes in superior average, 30% of the eyes in inferior average and 45% of the eyes in TSNIT SD. No significant correlation between enlarged corneal diameter and RNFL thickness was found.

CONCLUSIONS

The mean values of all standard TSNIT parameters assessed using GDxVCC in hydrophthalmic glaucomatous eyes in children were significantly lower in comparison with referential values of healthy age-matched children.

Association analysis of cigarette smoking with onset of primary open-angle glaucoma and glaucoma-related biometric parameters

Background

To date, studies on the role played by cigarette smoking in primary open-angle glaucoma (POAG) remains controversial. The current study evaluated cigarette smoking as a risk factor of POAG and its relationships with vertical cup-to-disc ratio (VCDR), central corneal thickness (CCT) and intraocular pressure (IOP) in a Chinese cohort.

Methods

In a total of 248 unrelated individuals including 30 juvenile-onset POAG (JOAG), 92 adult-onset POAG (AOAG) and 126 sex-matched senile cataract controls, underwent comprehensive ophthalmic examination. Their smoking was obtained and documented by questionnaire. Association of cigarette smoking with POAG was performed using logistic regression controlled for age and sex. Effects of cigarette smoking on VCDR, IOP and CCT were analyzed with multiple linear regression.

Results

In either JOAG or AOAG, no association of cigarette smoking was found with disease onset (P = 0.692 and 0.925 respectively). In controls and JOAG, no significant effects of smoking were found on VCDR, IOP or CCT (all P > 0.05). Smoking was found to be correlated with decreased CCT in AOAG and combined POAG (JOAG + AOAG) (P = 0.009 and 0.003), but no association with VCDR or IOP was observed (P > 0.05).

Conclusions

Although cigarette smoking was not found to be risk factor for onset of POAG, it was correlated with CCT in AOAG, and thus might still play a role in the disease course, especially for AOAG.

Comparison of Goldmann applanation and dynamic contour tonometry in a population of Mexican open-angle glaucoma patients

To compare intraocular pressure (IOP) measurements obtained with Goldmann applanation (GAT) and dynamic contour tonometry (DCT) in a Mexican population. 40 glaucoma patients were included in this cross-sectional observational cohort study. IOP measurements were performed in the following order: DCT, ultrasonic pachymetry and GAT, with a 5-minute difference between each measurement, between 8 am and 2 pm. Only DCT measurements of good quality (Q ≤ 3) were accepted. GAT measurements were made three times with the same Goldmann tonometer, previously checked for calibration errors, and the mean was used for statistical purposes. The IOP (mean [standard deviation], 95 % confidence interval [CI]) measured with the Goldmann tonometer (13.2 [2.4], 12.4-14.0 mmHg) was significantly lower than that obtained with the DCT (18.4 [3.3], 17.0-19.2 mmHg), p < 0.0001. Pearson's correlation coefficients between CCT and IOP measured with GAT and DCT were (r = 0.24, 95 % CI = 0.07-0.52, p = 0.133) and (r = 0.13, 95 % CI = -0.19 to 0.43, p = 0.412), respectively. The concordance correlation coefficient between GAT and DCT was r c = 0.3, 95 % CI = 0.17-0.41). DCT seems to overestimate the IOP as compared to GAT. Additionally, although there was a good correlation between the IOP measurements assessed with either GAT or DCT, the agreement was poor.

Effect of topical pressure-lowering medication on prevention of intraocular pressure spikes after intravitreal injection

Purpose. The aim of this study was to evaluate pressure increases after intravitreal injections (IVI) and the interest in using prophylactic pressure-lowering medications. 
Methods. This was a prospective study of 250 anti-vascular endothelial growth factor IVI (ranibizumab) divided into 5 groups of 50 IVI (group 1: no intraocular pressure [IOP]-lowering medication; group 2: apraclonidine 1%; group 3: acetazolamide; group 4: fixed association brimonidine + timolol; group 5: fixed association dorzolamide + timolol). The IOP was measured before, immediately after (T1), 15 minutes after (T15), and 45 minutes after (T45) the IVI using a tonometer. The data were analyzed by analysis of variance followed by a Bonferroni as post hoc test if necessary.
Results. The mean IOP peak in group 1 was 46.4±10 mmHg at T1, 21.7±10.2 mmHg at T15, and 15.4±8.6 mmHg at T45. It was not correlated with axial length (r=0.04, p=0.81) or lens status (phakic vs pseudophakic: p=0.88). A mild but significant correlation was found with age (r=0.36, p=0.006). Topical medications produced a significant reduction of IOP at every time point, of around 9 mmHg at T1. The reduction in IOP obtained with acetazolamide was not significant at T1 (-1.6 mmHg, p=0.12), but became significant at T15 and T45 (p=0.011 and p=0.015). 
Conclusions. Intraocular pressure spike was high but transient. Topical medications, however, produced a significant reduction in IOP spike as well as in the duration of the increased pressure. It would be advisable to prevent this IOP spike, especially when procedures are repeated, notably in patients with glaucoma.

[Comparison of dynamic contour tonometry, Goldmann and pneumotonometer in ocular hypertension patients and their relationship to pachymetry and ocular pulse amplitude]

PURPOSE

To determine the relationship between dynamic contour tonometry (DCT), Goldmann applanation tonometry (GAT) and pneumotonometry (PNT) in ocular hypertension patients (OHT) and their relationship to central corneal thickness (CCT) and ocular pulse amplitude (OPA).

METHODS

Sixty patients (101 eyes) with intraocular pressure (IOP) ≥21 mmHg using GAT and normal appearing optic nerve heads and normal visual fields were included. The following tests were performed simultaneously during a single visit: IOP using DCT, GAT and PNT, OPA using DCT and CCT using ultrasound pachymetry. We studied the difference IOP between these 3 tonometers using Wilcoxon non-parametric test and the effect of CCT on IOP and OPA, as well as the relationship between OPA and IOP using Spearman correlation coefficient.

RESULTS

The median PNT IOP was 24 mmHg (Inter-quartile range [IQR]: 22-26), median GAT IOP was 22 mmHg (IQR: 22-24), and median DCT IOP was 28.2 mmHg (IQR: 24.1-30.7). PNT and DCT had higher IOP values than GAT (median 2 mmHg and 6.2 mmHg, respectively). Mean CCT was 594.5 μm (SD 30.0). GAT IOP and DCT IOP showed an increase with increased corneal thickness (r:0.209; P=.036 and r:0.195; P=.051, respectively). PNT IOP did not change with CCT (r:0.15; P=.12). The median OPA was 4.8 mmHg (IQR: 3.6-6.1), and significantly increased with GAT IOP (r:0,38; P<.001) and with CCT (r:0.287; P=.004). This association was unclear with IOP PNT and IOP DCT (r:0.067; P=.50 and r:0,17, P=.08, respectively).

CONCLUSIONS

DCT and PNT IOP values were higher than GAT IOP measurements in ocular hypertension patients. GAT IOP showed a significant increase with increased corneal thickness. Increased OPA seems to correlate with increased CCT and IOP, particularly if GAT is used.

Icare ONE rebound versus Goldmann applanation tonometry in children with known or suspected glaucoma

PURPOSE

To compare Icare ONE tonometry by clinic examiner and parent/guardian to Goldmann applanation in children with known/suspected glaucoma; to evaluate the trend in intraocular pressure (IOP) with 4 repeated measurements using Icare ONE; and to evaluate the feasibility of instructing parents on the use of the Icare ONE device in the clinic setting.

DESIGN

Nonrandomized, prospective clinical study.

METHODS

Patients with known or suspected glaucoma were recruited from the Duke pediatric glaucoma clinic. Parent(s) of all subjects gave informed consent (and children gave assent) for participation in this research study. IOP was measured using Icare ONE by clinic examiner and parent/guardian, then using Goldmann applanation (masked physician). Each parent/guardian completed an ease-of-use survey.

RESULTS

Sixty eyes (60 children) were included. Absolute value of mean IOP difference (ICare ONE clinic examiner vs Goldmann applanation) was 3.3 ± 4.0 mm Hg (P = .001). Icare ONE IOP by clinic examiner was within 3 mm Hg of Goldmann applanation in 68% (n = 41 eyes). In eyes with >3 mm Hg difference, Icare ONE was higher than Goldmann applanation in 84%. IOP demonstrated a statistically significant downward trend with repeated sequential measurements with Icare ONE (P = .0053, r(2) = 0.9894). All parents accomplished Icare ONE tonometry on at least 1 eye; 98% reported it was "easy to learn to use."

CONCLUSION

Icare ONE tonometry appears accurate and well-tolerated compared to Goldmann applanation, and holds promise for clinic and home tonometry in children. IOP trends downward with successive measurements using Icare ONE, demonstrating a possible effect from presumed patient relaxation.

Evaluation of the Icare-ONE rebound tonometer as a self-measuring intraocular pressure device in normal subjects

PURPOSE

To compare Icare ONE rebound self-tonometer (ICRBT) measurements with Goldman applanation tonometry (GAT).

METHODS

A trained examiner instructed each of 60 normal subjects on use of the ICRBT. Each subject then took two measurements of his/her own pressure using the ICRBT. Finally, a different examiner, who was masked to the earlier readings, measured IOP by GAT. Bland–Altman limits of agreement (LOA), intraclass correlation coefficients (ICCs), Kappa values, and paired t-test were used to assess the agreement between the two methods. Pearson’s correlation coefficient was used for correlation analysis.

RESULTS

All of the subjects were able to obtain correct measurements with ICRBT after three attempts. The mean intraocular pressure with ICRBT and GAT measurements were 16.0 ± 3.3 mmHg and 13.7 ± 2.5 mmHg respectively. The mean difference between patient’s ICRBT and technician’s GAT measurements was 2.3 mmHg (p < 0.001). In 63% (38/60) of the cases the IOP difference (ICRBT − GAT) was within ± 3 mmHg. The weighted Kappa for the IOP measurements of the two methods was 0.49 (95% CI: 0.30–0.68, p < 0.001), indicating acceptable agreement. A significantly positive correlation was found between ICRBT IOP measurements and central corneal thickness (CCT) (r = 0.48, p < 0.001). In addition, the difference in IOP measurements (ICRBT − GAT) between the two methods was positively correlated with CCT (r = 0.31, p = 0.015), indicating that greater thickness is associated with greater differences between the two methods.

CONCLUSION

The ICRBT was reliable in the hands of normal subjects, and may be used for self-monitoring of IOP. ICRBT measurements generally overestimated GAT measurements.

Intravitreal injection of bevacizumab: changes in intraocular pressure related to ocular axial length

PURPOSE

To evaluate the immediate and short-term effects of intravitreal injection of 1.25 mg/0.05 ml of bevacizumab on intraocular pressure related to different ocular axial lengths.

DESIGN

A prospective case series of consecutive patients referred to the Department of Ophthalmology, San Pietro-Fatebenefratelli Hospital, from September 2011 through January 2011.

METHODS

Twenty-five patients (10 men and 15 women, mean age 70.2 ± 8.98 years) scheduled for intravitreal injection of bevacizumab for the treatment of neovascular age-related macular degeneration were enrolled in this study. Axial length was measured preoperatively using IOLMaster. Intraocular pressure was measured before injection, after 1 min and after 15 min using Tono-Pen XL tonometry.

RESULTS

The mean intraocular pressure change following the intravitreal bevacizumab injection was 21.92 ± 6.95 mmHg after 1 min and 6.24 ± 3.77 mmHg after 15 min. The mean axial length of the examined eyes was 23.2 ± 1.06 mm. A good correlation was observed between the axial length and intraocular pressure rise after both 1 (R (2) = 0.752, p < 0.001) and 15 min (R (2) = 0.559, p < 0.001).

CONCLUSIONS

Patients undergoing intravitreal injection of 0.05 ml of bevacizumab can be exposed to intraocular pressure increases correlated to ocular axial length.

Psychophysical and electrophysiological testing in ocular hypertension

PURPOSE

The purpose of this study was to compare psychophysical and electrophysiological testings in early optic nerve dysfunction in a group of clinically asymptomatic subjects with suspect ocular hypertension (OHT).

METHODS

Forty eyes of 40 patients with suspect OHT and asymmetrical horizontal cup/disc ratio (0.2/0.4), 22 eyes of 22 patients with open-angle glaucoma (OAG), and 40 eyes of 40 healthy controls were evaluated by using frequency-doubling technology perimetry (FDT), contrast sensitivity (CS), pattern electroretinography (PERG), and pattern visual-evoked potentials (VEP). The VEP were elicited by checkerboard stimuli with large (VEP 120), medium (VEP 45), and small (VEP 15) checks; then the values of the amplitude (A) and latency (L) of P100 peaks were studied. Receiver operator characteristic (ROC) curves were calculated to determine the sensitivity, specificity, and optimal cutoff points of abnormal values. A logistic regression analysis was performed to determine which tests were providing the most useful information. In addition, Kruskal-Wallis test was performed to test the differences between the control group and the OHT group.

RESULTS

VEP P100 peak latency (VEP L15 and VEP L45) and amplitude (VEP A120), PERG N95 peak amplitude, CS at medium spatial frequencies (CS 4SF), and FDT pattern standard deviation (PSD) yielded the greatest sensitivity (85.0 to 60.0%) and specificity (80.0 to 60.0%) ratio, displaying the largest ROC curve areas; whereas PERG N95 peak latency ROC curve had the smallest areas. Kruskal-Wallis test showed that most diagnostic tests were able to differentiate the OHT group from the control group. Stepwise logistic regression analysis identified VEP L15 (p < 0.001), CS 4SF (p = 0.023), FDT PSD (p = 0.032), and VEP A120 (p = 0.072) as tests that could be useful to distinguish controls from OHT.

CONCLUSIONS

Our data confirm that psychophysical and electrophysiological tests are useful for early detection of patients at risk of developing OAG.

Mechanisms compensating for visual field restriction in adolescents with damage to the retro-geniculate visual system

BACKGROUND

To describe visual field (VF) outcome in three adolescents with damage to the optic radiation and to focus on mechanisms that may compensate the practical functional limitations of VF defects.

DESIGN

Descriptive, prospective multi-case study in a hospital setting.

PARTICIPANTS

Three teenagers with cerebral visual dysfunction because of damage to the retro-geniculate visual pathways.

METHODS

Best-corrected visual acuity and eye alignment were assessed. Visual field function was tested with Goldmann perimetry, and with Rarebit, Humphrey Visual Field Analyzer and Esterman computerized techniques. Fixation was registered with video oculography during Rarebit examination. Magnetic resonance imaging of the brain illustrated brain damage and its relation to the posterior visual system.

RESULTS

One of the three subjects had bilateral asymmetric white matter damage of immaturity, early-onset exotropia, and a relative homonymous VF defect, but normal binocular VF. The second subject also had bilateral asymmetric white matter damage of immaturity and showed an inferior right quadrantanopia, confirmed by the binocular field. Registration of fixation revealed automatic scanning during perimetry. The third subject had an almost total left homonymous hemianopia after resection of a brain tumour in the right temporal lobe. The hemianopia could be compensated for by fast voluntary scanning.

CONCLUSION

Congenital and later-acquired homonymous VF defects may, at least in young subjects, be compensated for by scanning. Exotropia may compensate VF defects and, therefore, the VF should be tested before strabismus surgery.

[Comparison of the iCare tonometer with the Goldmann tonometer in Malawi]

BACKGROUND

The risk for glaucoma is 4-5 times higher in patients from sub-Saharan Africa. Thus, especially in developing countries an easy and effective method for assessing the intraocular pressure (IOP) is needed.

METHODOLOGY

In this hospital-based survey 150 eyes were divided into 3 groups concerning the IOP (group I < 16 mmHg, group II 16-23 mmHg and group III > 23 mmHg) and underwent examination with ultrasound pachymetry followed by iCare tonometry (ICT) and Goldmann applanation tonometry (GAT). Agreement of the measurements by two tonometers was assessed with the Bland-Altman method and the influence of the central corneal thickness (CCT) on the ICT measurements was determined.

RESULTS

The mean difference between the IOD measured with GAT and ICT was 0.84 ± 2.63 mmHg. The differences were similar in all three groups (0.77-0.97 mmHg), however, the standard deviation in group III (4.04 mmHg) was greater than in groups I (1.98 mmHg) and II (1.79 mmHg). The mean CCT was 513.51 ± 36.22 µm.

CONCLUSIONS

The agreement of measurements by GAT and ICT was good for lower IOP values but less accurate in patients with higher IOP values (group III). A dependency of the CCT on the ICT measurements was observed. In comparison to other countries the lowest CCTs were found in Malawian patients.