Comparation of the new rebound tonometer IOPen and the Goldmann tonometer, and their relationship to corneal properties

Purpose

To compare the intraocular pressures (IOPs) obtained with the IOPen rebound tonometer, Goldmann applanation tonometer (GAT) and the ocular response analyzer (ORA) and investigate the effects of corneal biomechanical properties on IOPen measurements.

Methods

A total of 198 normal eyes were included in this cross-sectional and randomized study. Three measurements were taken using IOPen. Agreement between tonometers was calculated using the Bland and Altman limits of agreement (LoA) analysis.

Results

The median IOPen IOP was 3 mm Hg below the GAT (P<0.001), 3 mm Hg below the ORA IOP similar to Goldmann (IOPg), and 3 mm Hg below the ORA IOP corrected using corneal parameters (IOPcc)(P<0.01). The LoA width between the IOPen and GAT IOPs varied between 13.92 (mean IOPen IOP) and 15.99 mm Hg (third IOPen measurement). The central corneal thickness (CCT) was unrelated to IOPen measurements (P>0.05). Corneal hysteresis (CH) and corneal rigidity factor (CRF) were correlated with IOPen and GAT.

Conclusions

IOPen underestimated the IOP compared with GAT and ORA. The effect of measurement quality or measurement order on IOPen was low. CCT did not affect the IOPen, but the CH and CRF did. The LoA width between the IOPen and GAT IOPs was higher than between the ORA IOPg or ORA IOPcc and GAT IOPs.     

Corneal hysteresis in patients with dry eye

Purpose

To measure corneal hysteresis and intraocular pressure (IOP) in patients with dry eye and to compare with normal subjects.

Methods

This cross-sectional study consists of 70 eyes of 40 patients with dry eye (group 1) and 75 eyes of 40 normal subjects (group 2). Eyes were diagnosed as dry eye or normal according to the clinical symptoms, biomicroscopical evaluation, and Schirmer test. Corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure (IOPcc) were measured by the Ocular Response Analyser (ORA).

Results

Mean CH values were 10.56±0.25 mm Hg and 10.34±0.26 mm Hg, mean CRF values were 10.75±0.28 mm Hg and 10.70±0.28 mm Hg, mean CCT values were 542±3.20 μm and 543±3.89 μm in group 1 and group 2, respectively. There was no statistically significant difference between the groups for these three parameters. IOPcc values measured with ORA were 15.73±0.36 mm Hg in group 1 and 16.60±0.33 mm Hg in group 2, and there was no statistically significant difference between the two groups.

Conclusions

Corneal biomechanical parameters such as CH and CRF are not influenced in dry eye. Also statistical difference was not found between the two groups according to CCT and IOPcc values.     

The influence of soft contact lenses on the intraocular pressure measurement

Purpose

To evaluate the influence of silicone hydrogel contact lenses on the intraocular pressure (IOP) measurement using Goldmann applanation tonometry (GAT), non-contact tonometry (NCT), and Pascal dynamic contour tonometry (DCT).

Methods

We included in the study 40 eyes of 40 patients who did not have any ocular or systemic diseases or contraindications to contact lens use. We measured and recorded the IOP values of each patient using NCT without and with contact lenses (groups 1 and 2, respectively), using DCT without and with contact lenses (groups 3 and 4, respectively), and using GAT without contact lenses (group 5).

Results

The mean IOP value of group 1 was 14.55±2.95 mm Hg and 13.92±2.58 mm Hg in group 2. We detected no statistically significant difference between group 1 and group 2 (P=0.053). The mean IOP values for group 3 and group 4 were 16.26±2.33 mm Hg and 15.19±2.40 mm Hg, respectively. We detected a statistically significant difference between groups 3 and 4 (P=0.005). Group 5''s mean IOP value was 12.97±2.65 mm Hg. IOP values measured with DCT were statistically significantly higher compared with IOP values measured with NCT and GAT (P<0.0001 and P<0.0001, respectively). Additionally, IOP values measured with NCT were statistically significantly higher compared with IOP values measured with GAT (P<0.0001).

Conclusion

According to the results of our study, silicone hydrogel soft contact lens use does not significantly affect IOP values measured with NCT, but it affects IOP values measured with DCT.     

Biodegradable collagen matrix implant vs mitomycin-C as an adjuvant in trabeculectomy: a 24-month, randomized clinical trial

Aim

To verify the safety and efficacy of Ologen (OLO) implant as adjuvant compared with low-dosage mitomycin-C (MMC) in trabeculectomy.

Methods

This was a prospective randomized clinical trial with a 24-month follow-up. Forty glaucoma patients (40 eyes) were assigned to trabeculectomy with MMC or OLO. Primary outcome includes target IOP at ≤21, ≤17, and ≤15 mm Hg; complete (target IOP without medications), and qualified success (target IOP regardless of medications). Secondary outcomes include bleb evaluation, according to Moorfields Bleb Grading System (MBGS); spectral domain optical coherence tomography (SD-OCT) examination; number of glaucoma medications; and frequency of postoperative adjunctive procedures and complications.

Results

The mean preoperative IOP was 26.5 (±5.2) in MMC and 27.3 (±6.0) in OLO eyes, without statistical significance. One-day postoperatively, the IOP dropped to 5.2 (±3.5) and 9.2 (±5.5) mm Hg, respectively (P=0.009). The IOP reduction was significant at end point in all groups (P=0.01), with a mean IOP of 16.0 (±2.9) and 16.5 (±2.1) mm Hg in MMC and OLO, respectively. The rates and Kaplan–Meier curves did not differ for both complete and qualified success at any target IOP. The bleb height in OLO group was higher than MMC one (P<0.05). SD-OCT analysis of successful/unsuccessful bleb in patients with or without complete success at IOP ≤17 mm Hg indicated a sensitivity of 83% and 73% and a specificity of 75% and 67%, respectively, for MMC and OLO groups. No adverse reaction to OLO was noted.

Conclusions

Our results suggest that OLO implant could be a new, safe, and effective alternative to MMC, with similar long-term success rate.     

Assessment of intraocular pressure measured by Reichert Ocular Response Analyzer, Goldmann Applanation Tonometry, and Dynamic Contour Tonometry in healthy individuals

AIM: To investigate the accuracy of intraocular pressure (IOP) as measured by a Reichert Ocular Response Analyzer (ORA), as well as the relationship between central corneal thickness (CCT) and IOP as measured by ORA, Goldmann applanation tonometry (GAT), and dynamic contour tonometry (DCT). METHODS: A total of 158 healthy individuals (296 eyes) were chosen randomly for measurement of IOP. After CCT was measured using A-ultrasound (A-US), IOP was measured by ORA, GAT, and DCT devices in a randomized order. The IOP values acquired using each of the three tonometries were compared, and the relationship between CCT and IOP values were analyzed separately. Two IOP values, Goldmann-correlated IOP value (IOPg) and corneal-compensated intraocular pressure (IOPcc), were got using ORA. Three groups were defined according to CCT: 1) thin cornea (CCT<520μm); 2) normal-thickness cornea (CCT: 520–580μm); and 3) thick cornea (CCT>580μm) groups. RESULTS: In normal subjects, IOP measurements were 14.95±2.99mmHg with ORA (IOPg), 15.21±2.77mmHg with ORA (IOPcc), 15.22±2.77mmHg with GAT, and 15.49±2.56mmHg with DCT. Mean differences were 0.01±2.29mmHg between IOPcc and GAT (P>0.05) and 0.28±2.20mmHg between IOPcc and DCT (P>0.05). There was a greater correlation between IOPcc and DCT (r=0.946, P=0.000) than that between IOPcc and GAT (r=0.845, P=0.000). DCT had a significant correlation with GAT (r=0.854, P=0.000). GAT was moderately correlated with CCT (r=0.296, P<0.001), while IOPcc showed a weak but significant correlation with CCT (r=?0.155, P=0.007). There was a strong negative correlation between CCT and the difference between IOPcc and GAT(r=-0.803,P=0.000), with every 10μm increase in CCT resulting in an increase in this difference of 0.35mmHg. The thick cornea group (CCT>580μm) showed the least significant correlation between IOPcc and GAT (r=0.859, P=0.000); while the thin cornea group (CCT＜520μm) had the most significant correlation between IOPcc and GAT (r=0.926, P=0.000). The correlated differences between IOPcc and DCT were not significant in any of the three groups (P>0.05). CONCLUSION: Measurement of IOP by ORA has high repeatability and is largely consistent with GAT measurements. Moreover, the ORA measurements are affected only to a small extent by CCT, and are likely to be much closer to the real IOP value than GAT.     

Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

Purpose:

To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK).

Materials and Methods:

Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA) values of normal and post-keratoplasty eyes [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc)], corneal topography, and central corneal thickness (CCT). Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman''s rho correlation.

Results:

The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P =0.311 and 0.276, respectively) while a significant correlation was observed with IOPg (P =0.004) and IOPcc (P < 0.001).

Conclusion:

Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.     

Comparison of trabeculectomy and Ex-PRESS implantation in fellow eyes of the same patient: a prospective, randomised study

Purpose

To compare intraocular pressure (IOP) over time after standard trabeculectomy vsEx-PRESS implantation in patients with bilateral primary open-angle glaucoma (POAG).

Design

Prospective, randomised study.

Patients and methods

This study included adult patients with bilateral POAG necessitating surgery. Each patient underwent trabeculectomy in one eye and Ex-PRESS implantation under a scleral flap in the other eye according to randomised contralateral allocations. Efficacy was assessed by IOP values and success rates (IOP threshold and/or need for topical glaucoma medication) during 30 months. Statistical analysis included Generalised Estimate Equation and Cox Survival models, and paired t-tests.

Results

Thirty eyes of 15 patients were studied for a mean of 23.6 months (SD, ±6.9). At the last follow-up visit, mean pre-operative IOP decreased from 31.1 (±14.2) to 16.2 (±1.5) mm Hg after trabeculectomy, and from 28.1 (±9.0) to 15.7 (±1.8) mm Hg after Ex-PRESS implantation (P=0.001). The mean number of anti-glaucoma medicines prescribed at the last follow-up decreased from 3.7 pre-operatively (both groups) to 0.9 after trabeculectomy vs0.3 after Ex-PRESS implantation (P=0.001). Complete success rates (5P=0.0024). Postoperative complications were more frequent after trabeculectomy (33%) compared with Ex-PRESS (20%), with four trabeculectomy eyes (27%) needing postoperative interventions, compared with none with Ex-PRESS.

Conclusions

Trabeculectomy and Ex-PRESS implantation provided similar IOP control, but the Ex-PRESS group had a lower rate of complications, fewer postoperative interventions, and needed less glaucoma medications.     

Deep sclerectomy with mitomycin C in eyes with failed glaucoma surgery and pseudophakia

Purpose

To report outcomes of deep sclerectomy (DS) with intraoperative mitomycin C (MMC) application in eyes with previous failed glaucoma surgery (GS) and/or cataract extraction (CE).

Patients and methods

Single-surgeon case series of 82 eyes of 82 patients undergoing DS with MMC. The patients had previous CE with IOL and/or conjunctival GS and treated intraocular pressure (IOP) >18 mm Hg. MMC (0.2 mg/ml) was applied for 2–3 min before scleral flap dissection. Complete success was defined as IOP between 6 and 21 mm Hg or a reduction of 20% from baseline without medications. Reoperation for glaucoma or related complications, or loss of light perception vision was considered as failure.

Results

Mean follow-up was 57.7±22.4 months with 78% of patients completing the 3-year follow-up. Mean IOP decreased from 24.0 mm Hg (22.3–25.6, 95% confidence intervals) to 13.4 mm Hg (12.0–14.2) at 3 years after surgery (P<0.001). There was a significant decrease in the number of glaucoma medications from 2.0±1 preoperatively, to 0.3±0.7, 3 years after surgery. Kaplan–Meier cumulative success rates were 85.6% at 1 year, 80.0% at 2 years, and 76% at 3 years. At 3 years, IOP was maintained <19 and 15 mm Hg in 83 and 70% of eyes, respectively. Fourteen eyes (17.1%) had complications. Delayed hypotony (IOP <6 mm Hg) was the commonest complication in five eyes (6.1%).

Conclusion

DS with MMC appears to be a safe and effective surgical procedure for eyes with previous intraocular surgery.     

Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty

Purpose

To compare intraocular pressure (IOP) measurements with Goldmann applanation tonometry (GAT) and iCare tonometry in normal and post-keratoplasty corneas and to assess the influence of central corneal thickness (CCT), corneal curvature (CC), and corneal astigmatism (CA) on IOP.

Methods

This prospective cross-sectional study included one eye of 101 subjects with normal corneas (58 healthy subjects, 43 glaucoma); and 90 post-keratoplasty patients: 34 penetrating keratoplasties (PK); 20 automated-lamellar-therapeutic keratoplasties (ALTK); 19 Descemet-stripping-automated-endothelial keratoplasties (DSAEK); 17 edematous grafts. All subjects underwent GAT and iCare IOP measurements in random order, and CCT, CC, and CA evaluation. The Bland–Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, CC, and CA on IOP.

Results

iCare significantly underestimated IOP in all groups compared with GAT (GAT minus iCare of 3.5±3.5 mm Hg, P<0.001), but overestimated IOP in the edematous grafts (GAT minus iCare of −6.5±1.9 mm Hg, P<0.001). In normal corneas, both tonometer measurements were directly related to CCT values; iCare readings appeared inversely related to CC. There was no significant relationship between IOP and CCT, CC and CA in post-keratoplasty eyes, except between CC and iCare measurements for PK eyes.

Conclusions

The agreement between GAT and iCare was clinically acceptable in control, ALTK and DSAEK groups, and poor in PK and edematous grafts eyes. In normal corneas, GAT was significantly affected by CCT; iCare was influenced by CCT and CC. The iCare appeared less influenced by corneal edema when compared with GAT. High IOP readings taken with both tonometers in grafts should raise suspicion of true elevated IOP.     

Evaluation of Corneal Biomechanical Properties Following Penetrating Keratoplasty Using the Ocular Response Analyzer

Purpose

To evaluate corneal biomechanical properties in eyes that had previously undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA).

Methods

We recruited 26 patients who had received unilateral PK. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc) were measured with the ORA and were compared to the measurements from the contralateral eyes that did not undergo PK.

Results

The CH was 8.95±2.59 mmHg in eyes that underwent PK and 9.78±1.45 mmHg in the contralateral eyes that did not undergo PK (p=0.077). The CRF was 10.26±2.64 mmHg in post-PK eyes and 9.75±1.45 mmHg in the contralateral eyes (p=0.509), and the CH-CRF was significantly smaller in post-PK eyes (-1.31±2.32 mmHg in post-PK eyes vs. 0.03±0.88 mmHg in fellow eyes, p=0.016). The IOPg and IOPcc were significantly higher in the PK group than they were in the control group. The IOPcc''s were 20.81±7.81 mmHg and 16.27±2.49 mmHg in post-PK and control eyes, respectively (p=0.011); and the IOPg''s were 19.22±7.34 mmHg and 15.07±3.03 mmHg in post-PK and control eyes, respectively (p=0.019). The IOPcc-g''s were 1.59±2.81 mmHg and 1.21±1.30 mmHg in post-PK and control eyes, respectively (p=0.412), and the central corneal thickness (CCT)''s were 489.11±90.60 µm and 556.24±42.84 µm in post-PK and control eyes, respectively (p=0.068).

Conclusions

Following PK, CH tended to decrease while CRF tended to increase, significantly decreasing CH-CRF. A significantly higher intraocular pressure and a thinner CCT following PK may have contributed to the observed changes in these corneal biomechanical parameters.     

Effect of trabeculectomy on RNFL thickness and optic disc parameters using optical coherence tomography

Purpose

To study the change in retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters using optical coherence tomography (Stratus OCT 3) after trabeculectomy in adult patients with glaucoma.

Methods

A total of 17 patients with glaucoma undergoing trabeculectomy were recruited. Average and quadrant RNFL thickness measurements, vertical integrated rim area, horizontal integrated rim width, disc area, cup area, and rim area were measured using Stratus OCT within a week before surgery and at 1 week, 1 and 3 months postoperatively. Main outcome measures were change in RNFL and ONH parameters. Pre- and postoperative values were analysed using the Wilcoxon signed-rank test.

Results

Intraocular pressure (IOP) reduced from 30.23±9.02 mm Hg preoperatively to 9.52 ±2.42 mm Hg at 1 week, 12.35±4.59 mm Hg at 1 month, and 13.6 ±2.31 mm Hg at 3 months after trabeculectomy. A significant increase in average (P=0.019) and inferior RNFL (P=0.038) thickness was observed 1 week after surgery. At 3 months postoperatively, they had reverted to preoperative values. RNFL thickness change had no correlation with IOP change. Mean optic disc cup area decreased from 2.39±0.52 mm² preoperatively to 2.14±0.52 mm² at 1 week (P=0.022), 2.22±0.53 mm² at 1 month (P=0.038), and 2.27±0.60 mm² at 3 months (P=0.071). No significant change was found in other ONH parameters.

Conclusions

Short-term fluctuations were noted in RNFL thickness and ONH postoperatively following glaucoma filtration surgery. RNFL thickness temporarily increased and cup area decreased but the values reverted to normal within 3 months.     

Increased intraocular pressure on the first postoperative day following resident-performed cataract surgery

Purpose

The aim of this study was to investigate the incidence of intraocular pressure (IOP) elevation after resident-performed cataract surgery and to determine variables, which influence postoperative day 1 (POD1) IOP.

Methods

In all, 1111 consecutive cataract surgeries performed only by training residents between 1 July 2001 and 30 June 2006 were included. Elevated IOP was defined as ≥23 mm Hg. Surgeries were classified according to the presence of POD1-IOP elevation. Fisher''s exact test and Student t-test were used to compare both groups. Multivariate analyses using generalized estimating equations were performed to investigate predictor variables associated with POD1-IOP elevation.

Results

The average preoperative IOP was 16.0±3.2 mm Hg and the average POD1-IOP was 19.3±7.1 mm Hg, reflecting a significant increase in IOP (P<0.001, paired t-test). The incidence of POD1-IOP elevation ≥23 mm Hg was 22.0% (244/1111). Presence of glaucoma and ocular hypertension, higher preoperative IOP, and longer axial length were frequently encountered variables in the POD1-IOP elevation group (all P<0.05). Using a multivariate analysis, presence of glaucoma (P=0.004, OR=2.38; 95% confidence interval (95% CI)=1.31–4.30), presence of ocular hypertension (P=0.003, OR=6.09; 95% CI=1.81–20.47), higher preoperative IOP (P<0.001, OR=3.73; 95% CI=1.92–7.25), and longer axial length (P=0.01, OR=1.15; 95% CI=1.03–1.29) were significant predictive factors for POD1-IOP elevation.

Conclusions

IOP elevation on the first postoperative day following resident-performed cataract surgery occurred frequently (22.0%). Increased early postoperative IOP was associated with presence of glaucoma and ocular hypertension, higher preoperative IOP, and longer axial length.     

Travoprost 0.004%/timolol 0.5%-fixed combination with and without benzalkonium chloride: a prospective, randomized, doubled-masked comparison of safety and efficacy

Purpose

The purpose of this study is to compare the safety and intraocular pressure (IOP)-lowering efficacy of travoprost/timolol in a benzalkonium chloride (BAK)-free fixed combination preserved with polyquaternium-1 (TRA/TIM BAK-free), with travoprost/timolol-fixed combination preserved with BAK (TRA/TIM), in patients with open-angle glaucoma or ocular hypertension.

Methods

In this prospective randomized controlled trial, subjects with IOP of at least 22 mm Hg in one or both eyes at 0900 h, and IOP of at least 21 mm Hg in one or both eyes at 1100 h and 1600 h at two eligibility visits were randomly assigned to receive either TRA/TIM BAK-free (n=195) or TRA/TIM (n=193), dosed once daily in the morning (0900 h) for 6 weeks. IOP was assessed at 0900 h, 1100 h, and 1600 h at each scheduled visit (baseline, 2 and 6 weeks after randomization).

Results

Mean IOP reduction across all visits and time points was 8.0 mm Hg in the TRA/TIM BAK-free group and 8.4 mm Hg in the TRA/TIM group (P=0.0943). The difference in mean IOP between groups ranged from 0.2 to 0.7 mm Hg across visits and time points, with a mean pooled difference of 0.4 mm Hg (95% CI: −0.1 to 0.8), demonstrating equivalence of the two formulations. The most common drug-related adverse event was hyperemia of the eye (ocular hyperemia and conjunctival hyperemia combined), occurring in 11.8% of the TRA/TIM BAK-free group and 13.0% of the TRA/TIM group.

Conclusion

Travoprost/timolol BAK-free demonstrated equivalence to travoprost/timolol preserved with BAK in efficacy. No clinically relevant differences in the safety profiles of travoprost/timolol BAK-free and travoprost/timolol preserved with BAK were identified.     

Association between corneal biomechanical properties and myopia in Chinese subjects

Purpose

To examine the relationship between corneal biomechanical properties and the degree of myopia.

Methods

Chinese subjects (n=172, age: 11−65 years) were divided into diagnostic groups with non-myopia (spherical equivalence (SE)>−0.50 D), low (−3.00≤SE≤−0.50 D), moderate (−6.00≤SE<−3.00 D), and high myopia (SE<−6.00 D). Only the right eye of each subject was analyzed. Central corneal thickness (CCT) was measured by optical coherence tomography. An ocular response analyzer was used to measure corneal hysteresis (CH), corneal resistance factor (CRF), intraocular pressure (IOP), and corneal compensated IOP (IOPcc). Refraction was measured by both automated and subjective refractometry and expressed as SE.

Results

CH was significantly lower in high myopia compared with both low and non-myopia (P≤0.002). CCT was 1.5 times more correlated to CH variation compared with refraction. Similarly, CRF was four times more dependent on CCT than refraction. CH (P<0.001) or CRF (P=0.005) was positively correlated to refraction. Both IOP and IOPcc were negatively correlated to refraction (P<0.001), respectively.

Conclusions

CH decreases only in high myopia. Refraction is positively correlated to both CH and CRF but negatively correlated to both IOP and IOPcc. These results indicate that the mechanical strength in anterior segment of the eye is compromised in high myopia. In addition, high myopia may increase the risk of glaucoma.     

Factors associated with topographic changes of the optic nerve head induced by acute intraocular pressure reduction in glaucoma patients

Purpose

To investigate factors associated with changes in optic nerve head (ONH) topography after acute intraocular pressure (IOP) reduction in patients with primary open-angle glaucoma (POAG).

Methods

Untreated POAG patients (IOP >21 mm Hg) were prospectively enrolled. Systemic and ocular information were collected, including central corneal thickness (CCT) and corneal hysteresis (CH). All patients underwent confocal scanning laser ophthalmoscopy and tonometry (Goldmann) before and 1 h after pharmacological IOP reduction. The mean of three measurements was considered for analysis. Changes in each ONH topographic parameter were assessed (one eye was randomly selected), and those that changed significantly were correlated with patient''s systemic and ocular characteristics.

Results

A total of 42 patients were included (mean age, 66.7±11.8 years). After a mean IOP reduction of 47.3±11.9%, significant changes were observed in cup area and volume, and in rim area and volume (P<0.01), but not in mean cup depth (P=0.80). Multiple regression analysis (controlling for baseline IOP and magnitude of IOP reduction) showed that CH (r²=0.17, P<0.01) and diabetes diagnosis (r²⩾0.21, P<0.01) were negatively correlated with the magnitude of changes in ONH parameters, whereas the cup-to-disc ratio was positively correlated (r²=0.30, P<0.01). Age, race, disc area, and CCT were not significant (P⩾0.12). Including all significant factors in a multivariable model, only the presence of diabetes remained significantly associated with all ONH parameters evaluated (P<0.01).

Conclusions

Different systemic and ocular factors, such as diabetes, CH, and the relative size of the cup, seem to be associated with the magnitude of changes in ONH topography after acute IOP reduction in POAG patients. These associations partially explain the ONH changes observed in these patients and suggest that other factors are possibly implicated in an individual susceptibility to IOP.     

Comparison of postoperative intraocular pressure changes between 23-gauge transconjunctival sutureless vitrectomy and conventional 20-gauge vitrectomy

Purpose

To compare the intraocular pressure (IOP) after 23-gauge transconjunctival sutureless vitrectomy (TSV) and conventional 20-gauge vitrectomy for various vitreoretinal diseases.

Methods

This was a retrospective interventional case series including 338 cases of 23-gauge TSV and 476 cases of 20-gauge vitrectomy with minimum follow-up period of 1 month. Postoperative 1 day, 1 week and 1 month IOPs were compared. Multiple regression analysis to assess the actual effect of gauge of vitrectomy on postoperative IOP was performed including intraoperative and postoperative factors influencing postoperative IOP as covariates.

Results

The mean IOP of 20-gauge vitrectomy was significantly higher than that of 23-gauge TSV (20.6±8.02 mm Hg vs12.8±4.48 mm Hg, P<0.001) at postoperative day 1, but the differences were not significant at postoperative 1 week and 1 month. The IOP pattern of 23-gauge TSV demonstrated more stable course than that of 20-gauge vitrectomy. At 1 day post vitrectomy, the incidence of hypertony was higher in 20-gauge, whereas that of hypotony was higher in 23-gauge. Among risk factors, the 20-gauge vitrectomy showed the strongest association with postoperative 1 day IOP rise.

Conclusion

Twenty-three-gauge TSV has stable and lower IOP in the early postoperative period than the 20-gauge vitrectomy. In patients whose retina and optic nerves are vulnerable to higher or fluctuating IOP, 23-gauge TSV may be more beneficial.     

The effect of contact lens induced oedema on the accuracy of Goldmann tonometry in a mature population

Aim

To determine the effect of contact lens induced oedema on the accuracy of Goldmann tonometry measurements of intraocular pressure (IOP) in mature subjects.

Methods

22 healthy subjects aged between 50 and 60 years were recruited. Corneal curvature, IOP, and central corneal thickness (CCT) were measured before and after two hours of monocular closed eye wear of a thick hydroxyethyl methacrylate (HEMA) contact lens. Measurements were then repeated at 20 minute intervals for one hour after lens removal.

Results

Both CCT (+54.1 μm) and IOP (+2.7 mm Hg) increased significantly after lens wear (p<0.001, paired t test with Bonferroni correction). For the hour following lens removal, the measured IOP was correlated to the increase in CCT (r = 0.84, p<0.001), at a rate of 1.0 mm Hg/10 μm (95% confidence interval, 0.8 to 1.2 mm Hg/10 μm, linear mixed model analysis).

Conclusions

A relatively small increase in CCT from contact lens induced corneal oedema caused an overestimation error in Goldmann tonometry measurements of IOP in healthy mature subjects.     

Comparison of ocular response analyzer parameters in primary open angle glaucoma and exfoliative glaucoma patients

Aim:

We sought to identify differences in the following measures of the ocular response analyser (ORA) between primary open angle glaucoma (POAG) and exfoliative glaucoma (EXG) patients: Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg). We also sought to relate these ORA measures with central corneal thickness (CCT).

Materials and Methods:

This cross-sectional study was conducted on a total of 162 individuals (46 EXG patients, 66 POAG patients and 50 healthy subjects without any ocular and systemic disease). ORA measurements were performed, and a minimum of three readings were obtained from each test subject. Groups were compared according to their ORA parameters.

Results:

The mean CH levels of the EXG, POAG and healthy subjects were 7.6 ± 2.1, 9.1 ± 1.9 and 9.6 ± 1.7 mmHg, respectively. CH was significantly lower in the EXG patients compared to the other groups (P < 0.001). The mean CRF levels of the EXG, POAG and healthy subjects were 9.0 ± 2.0, 10.1 ± 1.7 and 9.8 ± 1.8mmHg, respectively. CRF levels in the eyes of the EXG patients were significantly lower compared to those of either the POAG patients (P = 0.005) or the healthy subjects (P = 0.03), but there was no significant difference in CRF levels between the POAG patients and the healthy subjects (P = 0.59). There was a significant positive correlation between CH and CCT in the EXG patients and healthy subjects (P < 0.001), but this correlation was not present in the POAG patients (P = 0.70).

Conclusions:

In this study, CH and CRF were found to be significantly reduced in the eyes of EXG patients compared to both the POAG patients and healthy subjects. Reduced CH in EXG patients might result in decreased support of peripapillary scleral structure and increased damage to the optic nerve during IOP increase.     

Short-term changes in the optic nerve head and visual field after trabeculectomy

Aims or Purpose

To evaluate short-term changes in optic nerve head topography and visual field induced by surgical reduction of intraocular pressure.

Methods

A prospective study was performed on 56 eyes of 56 patients with uncontrolled primary open-angle glaucoma despite maximum medical therapy, which underwent trabeculectomy. Optic nerve head evaluations by means of Heidelberg Retina Tomograph, and visual field tests were performed pre-operatively, and at 3 and 6 months after surgery. Differences in intraocular pressure, visual field indices, and Heidelberg Retina Tomograph parameters were evaluated with the t-test for paired data. A linear regression model was calculated to analyze the relationship between intraocular pressure reduction and visual field changes, and optic nerve head changes.

Results

Mean intraocular pressure decreased from 24.4±5.0 mm Hg to 12.1±3.1 mm Hg (month 3, P<0.001), and 10.6±2.8 mm Hg (month 6, P<0.001) after trabeculectomy. Mean retinal nerve fiber layer thickness (baseline, 0.19±0.034; month 3, 0.24±0.039, P=0.05; month 6, 0.21±0.037, P=0.05) showed a statistical significant change compared with baseline values.

Conclusions

In this 6-months study, a significant increase in retinal nerve fiber layer thickness was detected after glaucoma filtration surgery.     

Effects of caffeinated coffee consumption on intraocular pressure, ocular perfusion pressure, and ocular pulse amplitude: a randomized controlled trial

Purpose

To examine the effects of caffeinated coffee consumption on intraocular pressure (IOP), ocular perfusion pressure (OPP), and ocular pulse amplitude (OPA) in those with or at risk for primary open-angle glaucoma (POAG).

Methods

We conducted a prospective, double-masked, crossover, randomized controlled trial with 106 subjects: 22 with high tension POAG, 18 with normal tension POAG, 20 with ocular hypertension, 21 POAG suspects, and 25 healthy participants. Subjects ingested either 237 ml of caffeinated (182 mg caffeine) or decaffeinated (4 mg caffeine) coffee for the first visit and the alternate beverage for the second visit. Blood pressure (BP) and pascal dynamic contour tonometer measurements of IOP, OPA, and heart rate were measured before and at 60 and 90 min after coffee ingestion per visit. OPP was calculated from BP and IOP measurements. Results were analysed using paired t-tests. Multivariable models assessed determinants of IOP, OPP, and OPA changes.

Results

There were no significant differences in baseline IOP, OPP, and OPA between the caffeinated and decaffeinated visits. After caffeinated as compared with decaffeinated coffee ingestion, mean mm Hg changes (±SD) in IOP, OPP, and OPA were as follows: 0.99 (±1.52, P<0.0001), 1.57 (±6.40, P=0.0129), and 0.23 (±0.52, P<0.0001) at 60 min, respectively; and 1.06 (±1.67, P<0.0001), 1.26 (±6.23, P=0.0398), and 0.18 (±0.52, P=0.0006) at 90 min, respectively. Regression analyses revealed sporadic and inconsistent associations with IOP, OPP, and OPA changes.

Conclusion

Consuming one cup of caffeinated coffee (182 mg caffeine) statistically increases, but likely does not clinically impact, IOP and OPP in those with or at risk for POAG.