Changes in intraocular pressure and central corneal thickness during pregnancy: a systematic review and Meta-analysis

AIM: To conduct a Meta-analysis for investigating the variations in intraocular pressure (IOP) and central corneal thickness (CCT) during normal pregnancy. METHODS: We searched for clinical trials published up to November 2015 without language or region restrictions in PubMed, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, Ovid, EBSCO, Elsevier, the Chinese Biomedicine Database, WanFang, CNKI, CQVIP and Google Scholar. Studies of the ocular changes observed in pregnant women were selected. The main outcomes were assessed by changes in IOP and CCT. RESULTS: Fifteen studies were included. In subgroup analyses, IOP was significantly decreased during the second MD=-1.53, 95%CI (-2.19, -0.87); P<0.00001, and third MD=-2.91, 95%CI (-3.74, -2.08); P<0.00001 trimesters of pregnancy. CCT was increased during the second MD=10.12, 95%CI (2.01, 18.22); P=0.01, trimester of pregnancy; moreover, during the third trimester of pregnancy, the CCT displayed an increasing trend, but the difference was not significant MD=5.98, 95%CI (-1.11, 13.07); P=0.1. CONCLUSION: A decrease in IOP is accompanied by an increase in CCT in the second and third trimesters of a normal pregnancy in women.     

Assessment of the diurnal variation in central corneal thickness and intraocular pressure for patients with suspected glaucoma

OBJECTIVE: To assess whether a single daily measurement using ultrasonic pachymetry gives a representative assessment of mean central corneal thickness (CCT) in patients with suspected glaucoma and whether diurnal changes in CCT are related to diurnal variations in intraocular pressure (IOP). DESIGN: Cross-sectional study. METHOD: Central CCT and IOP were measured by a single observer in 56 eyes of 28 patients with suspected glaucoma using an ultrasonic pachymeter and a Goldmann tonometer. Four measurements were made over a 24-hour period: at 8:00 AM, 12:00 PM, 4:00 PM, and 8:00 PM. MAIN OUTCOME MEASURES: Intraocular pressure and pachymetry. RESULTS: Mean IOP was 19.80 mmHg at 8:00 AM (95% confidence interval [CI], 18.95-20.66 mmHg), 20.38 mmHg at 12:00 PM (95% CI, 19.49-21.26 mmHg), 19.91 mmHg at 4:00 PM (95% CI, 19.99-21.83 mmHg), and 19.23 mmHg at 8:00 PM (95% CI, 18.35-20.11 mmHg). Mean CCT was 569.4 microm (95% CI, 560.2-578.7 microm), 567.6 microm (95% CI, 558.4-576.7 microm), 569.1 microm (95% CI, 559.5-578.6 microm), and 567.2 microm (95% CI, 557.9-576.4 microm) at the four respective time points. There was no significant correlation between IOP and CCT in any patient (Pearson rank correlation coefficient); nor was there any significant correlation between the mean diurnal variations of IOP and CCT. CONCLUSIONS: In this group of patients with suspected glaucoma, there was no significant variation in CCT. Therefore, a single measurement of CCT is sufficient when assessing patients with suspected glaucoma. There was no correlation between change of IOP and change of CCT.     

Relationship between travoprost and central corneal thickness in ocular hypertension and open-angle glaucoma

PURPOSE: To evaluate whether treatment with travoprost, an F2a prostaglandin analog, affects central corneal thickness (CCT) and whether intraocular pressure (IOP) response to the medication is related to baseline CCT. METHODS: This was a prospective, interventional, nonrandomized, nonconsecutive, clinical trial. In this multicenter study, 379 total patients, 220 with newly or previously diagnosed open-angle glaucoma (OAG), 141 with ocular hypertension (OHT), and 18 unspecified, were recruited from 15 Canadian sites. IOP and CCT assessments were performed at baseline and 6 weeks after treatment with travoprost. Patients on IOP-lowering therapy at the time of enrollment were washed out for 4 weeks before baseline examinations. IOP was measured with Goldmann tonometers and CCT with Accutome IV pachymeters. Statistical analysis was performed with S-PLUS software. RESULTS: Posttherapy mean IOP decreased by 6.31 mm Hg or 24.4% (P < 0.001), and regression analysis indicated relatively greater IOP reduction in patients with higher pretherapy IOP (slope = 0.64; 95% CI, 0.54-0.76). Mean CCT decreased by 6.9 microm (P < 0.001). IOP reduction was not related to CCT reduction (slope = 0.253; 95% CI, -0.232 to 0.739; P = 0.305). Percent IOP decrease was not related to baseline CCT (slope = -0.02; 95% CI, -0.06 to 00.02; P = 0.33) in the total study sample. When OHT and OAG groups were considered separately, the OAG patients had less percent IOP decrease with thicker baseline CCT (slope = -0.067; 95% CI, -0.13 to -0.004; P = 0.037). CONCLUSIONS: Treatment with travoprost decreased IOP significantly and was associated with CCT thinning, which had little or no effect on actual IOP decrease. In the OAG group, IOP decrease was found to be statistically smaller in patients with thicker corneas.     

Fixed combination of latanoprost and timolol vs the individual components for primary open angle glaucoma and ocular hypertension:a systematic review and meta-analysis

AIM:To assess the effects of the fixed combination of 0.005% latanoprost and 0.5% timolol (FCLT) vs their individual components for primary open angle glaucoma (POAG) and ocular hypertension (OHT).METHODS:After searched PubMed, EMBASE, the Cochrane Library and SCI, all randomized controlled clinical trials (RCTs) and cross-over studies were included. The control groups were the mono therapy or the concomitant therapy of latanoprost and timolol. The outcomes were visual field defect, optic atrophy, mean intraocular pressure (IOP) and IOP fluctuation. The analysis was carried out in RevMan version 5.1 software.RESULTS:The post-intervention mean IOP of FCLT was significantly lower compared to timolol [mean difference (MD) -2.92, 95%CI -3.28 to -2.55, P<0.00001] and latanoprost (MD -1.11, 95%CI -1.51 to -0.72, P＜0.00001). The post-intervention IOP fluctuation was also significantly lower compared to timolol (MD -0.88, 95%CI -1.23 to -0.53, P<0.00001) and latanoprost (MD -0.63, 95%CI -1.04 to -0.22, P=0.002). The mean IOP was higher in FCLT morning dose group than the one in unfixed combination of 0.005% latanoprost and 0.5% timolol (UFCLT) (MD 1.10, 95%CI 0.81 to 1.39, P<0.00001). Otherwise, there was no difference between FCLT evening dose group and UFCLT (MD 0.34, 95% CI -0.01 to 0.69, P=0.06). There was no statistical difference for the incidence of visual field defect and optic atrophy between FCLT and the monotherapy of components.CONCLUSION:A better IOP lowering effect has been demonstrated for FCLT compared to the mono therapy of components. The IOP lowering effect was worse for FCLT morning dose and almost same for FCLT evening dose compared to the UFCLT. We need more long-term high quality RCTs to demonstrate the outcomes of visual field defect and optic atrophy.     

Effect of pregnancy on intraobserver and intertechnique agreement in intraocular pressure measurements

AIM: To evaluate the effect of pregnancy on intraobserver and intertechnique agreement for intraocular pressure (IOP) measurements. MATERIAL AND METHODS: Right eyes of 88 healthy women who were likely to become pregnant and of 94 healthy age-matched females were included in the study. Complete ocular examinations were performed on each eye. IOP measurements were obtained by Goldmann, Schiotz and non-contact tonometers (NCT) during 3-week exam periods before (within 6 weeks of conception) and during pregnancy (first, second and third trimesters) for pregnant cases, and in similar time intervals for control subjects. In each exam period, three readings with each of three separate tonometers were obtained, at least 1 day apart. Intraobserver and intertechnique agreements for IOP measurements were assessed. RESULTS: The mean visual acuity, keratometry and refractive error of both control and pregnant subjects did not change significantly during the study (all p values >0.01). In late pregnancy, pregnant cases demonstrated significant decreases in IOP measurements obtained with each of the three tonometers, and in intraobserver agreement with Goldmann and Schiotz tonometers (all p values <0.01). Intertechnique agreement of both Goldmann and Schiotz tonometers with NCT decreased significantly in the third trimester. Both intraobserver and intertechnique agreement in IOP measurements of control subjects were not found to change significantly during the study (all p values >0.01). CONCLUSION: IOP significantly decreased in the third trimester of pregnancy. Perfect intraobserver agreement in IOP readings of pregnant subjects was obtained with NCT. This may suggest that NCT is a viable option for IOP measurements during the follow-up of pregnant patients at risk for glaucoma.     

Phacoemulsification versus combined phacotrabeculectomy in the treatment of primary angle-closure glaucoma with cataract: a Meta-analysis

AIM: To compare the efficacy and safety of phacoemulsification (Phaco) against combined phacotrabeculectomy (Phacotrabe) in primary angle-closure glaucoma (PACG) with coexisting cataract. METHODS: By searching electronically the PubMed, EMBASE, Scientific Citation Index and Cochrane Library published up from inception to January 2014, all randomized controlled trials that matched the predefined criteria were included. The quality of included trials was evaluated according to the guidelines developed by the cochrane collaboration. And the outcomes estimating efficacy and safety of two different surgical treatments were measured and synthesised by RevMan 5.0. RESULTS: Five randomized controlled trials were selected and included in Meta-analysis with a total of 468 patients (468 eyes) with both PACG and cataract. We found that Phacotrabe had a greater intraocular pressure (IOP) lowing effect [preoperative IOP: weighted mean difference (WMD)=0.58, 95% confidence intervals (95% CI, -0.53 to 1.69), P=0.31; postoperative IOP: WMD=1.37, 95% CI (0.45 to 2.28), P=0.003], a lower number of anti-glaucoma medications [ risk ratio (RR) =0.05, 95% CI (0.02 to 0.18), P<0.00001] needed postoperatively and less serious damage of optic nerve [risk ratio (RR)=0.48, 95% CI (0.21 to 1.07), P=0.07], but a higher risk of complications [odds ratio (OR) =0.04, 95% CI (0.01 to 0.16), P<0.00001] compared with Phaco. The rest studies indicated that there had no significantly difference between the two surgical methods for postoperative best-corrected visual acuity (BCVA) [WMD=-0.05, 95% CI (-0.14 to 0.05), P=0.32] and loss of visual field [OR=1.06, 95% CI (0.61 to 1.83), P=0.83]. CONCLUSION: Phaco alone compared with Phacotrabe had a better effect in IOP reduction, whereas the security decline. Considering the number of sample size, our results remains to be further studied.     

Mitomycin C application after photorefractive keratectomy in high,moderate, or low myopia: Systematic review and meta-analysis

Photorefractive keratectomy (PRK) is considered a safe approach laser procedure with a clinical significance in correcting myopia results. PRK requires removing the whole superficial epithelium. The integrity of the epithelial basement membrane and the deposition of abnormal extracellular matrix can put the cornea in a probable situation for corneal haze formation. Mitomycin C (MMC) is applied after excimer laser ablation as a primary modulator for wound healing, limiting corneal haze formation. We aim to summarize the outcomes of MMC application after laser ablation. We searched Scopus, PubMed, Cochrane CENTRAL, and Web of Science till December 2020 using relevant keywords. The data were extracted and pooled as mean difference (MD) or risk ratio (RR) with a 95% confidence interval (CI), using Review Manager software (version 5.4). Our analysis demonstrated a statistically significant result for MMC application over the control group in terms of corneal haze formation postoperatively (RR = 0.29, 95% CI: [0.19, 0.45], P < 0.00001). Regarding corrected distance visual acuity (CDVA), no significant difference was observed between the MMC group and the control group (MD = 0.02; 95% CI: [-0.04, 0.07]; P = 0.56). Regarding the uncorrected distance visual acuity (UDVA), the analysis favored the MMC application with (MD -0.03, 95% CI: [-0.06, -0.00]; P = 0.05). There was no statistically significant increase in complications with MMC. In conclusion, MMC application after PRK is associated with a lower incidence of corneal haze formation with no statistically significant side effects. The long term effect can show improvement regarding UDVA favoring MMC. However, there is no significant effect of MMCs application regarding CDVA, and SE.     

玻璃酸钠联合rhEGF滴眼液治疗白内障术后干眼疗效的Meta分析

目的:运用Meta分析方法系统评价近5a玻璃酸钠联合重组人表皮生长因子(rhEGF)滴眼液治疗白内障术后干眼的疗效。方法:计算机检索2015-01/2020-05中国知网数据库、万方数据库、重庆维普中文科技期刊全文数据库、中国生物医学文献数据库(CBM)、Cochrane Library、PudMed、MEDLINE等数据库关于采用玻璃酸钠联合rhEGF滴眼液治疗白内障术后干眼的的临床对照研究相关文献,使用Rev-man 5.3统计软件进行Meta分析和统计处理。结果:共纳入14项随机对照研究,患眼1529例。其中14项研究在治疗结束后进行了角膜荧光素染色(FL)评分,结果显示差异有统计学意义[MD=-0.86,95%CI(-1.07~-0.66),P<0.00001];14项研究在治疗结束后进行了泪膜破裂时间(BUT)测定,结果显示差异有统计学意义[MD=2.33,95%CI(1.64~3.03),P<0.00001];12项研究在治疗结束后进行了泪液分泌试验(SⅠt)测定,结果显示差异无统计学意义[MD=0.49,95%CI(-0.52~1.50),P=0.34];12项研究在治疗结束后进行了总体有效率计算,结果显示差异有统计学意义[OR=4.88,95%CI(3.34~7.14),P<0.00001];4项研究在治疗结束后进行了干眼症状评分测定,结果显示差异有统计学意义[MD=-1.09,95%CI(-1.58~-0.61),P<0.00001]。结论:玻璃酸钠联合rhEGF滴眼液治疗白内障术后干眼能显著提高角膜修复能力和BUT,在治疗白内障术后干眼总体疗效上更具优势。     

The relative effects of corneal thickness and age on Goldmann applanation tonometry and dynamic contour tonometry

AIMS: To establish the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measured with a prototype Pascal dynamic contour tonometer (DCT), to evaluate the effect of CCT and age on the agreement between IOP measured with the Pascal DCT and Goldmann applanation tonometer (GAT), and to compare the interobserver and intraobserver variation of the DCT with the GAT. METHODS: GAT and DCT IOP measurements were made on 130 eyes of 130 patients and agreement was assessed by means of Bland-Altman plots. The effect of CCT and age on GAT/DCT IOP differences was assessed by linear regression analysis. Interobserver and intraobserver variations for GAT and DCT were assessed in 100 eyes of 100 patients. RESULTS: The mean difference (95% limits of agreement) between GAT and DCT was -0.7 (-6.3 to 4.9) mm Hg. GAT/DCT IOP differences increased with thicker CCT (slope 0.017 mm Hg/microm, 95% CI 0.004 to 0.03, r2 = 0.05, p = 0.01), and with greater age, slope 0.05 mm Hg/year (95% CI 0.012 to 0.084, r2 = 0.05, p = 0.01). The intraobserver variability of GAT and DCT was 1.7 mm Hg and 3.2 mm Hg, respectively. The interobserver variability was (mean difference (95% limits of agreement)) 0.4 (-3.5 to 4.2) mm Hg for GAT and 0.2 (-4.9 to 5.3) mm Hg for DCT. CONCLUSIONS: GAT is significantly more affected than DCT by both CCT and subject age. The effect of age suggests an age related corneal biomechanical change that may induce measurement error additional to that of CCT. The prototype DCT has greater measurement variability than the GAT.     

Outcome comparison between wavefront-guided and wavefront-optimized photorefractive keratectomy: A systematic review and meta-analysis

Photorefractive keratectomy (PRK) eye surgery is widely used for patients at risk for corneal ectasia to maintain an aspheric corneal shape. Wavefront-guided (WFG) ablation profile was designed to reduce pre-existing higher-order aberrations (HOA). We aimed to compare the corneal aberrations and visual outcomes between WFG and Wavefront Optimized (WFO) PRK in patients with myopia. Eight randomized clinical trials were included. We searched PubMed, Scopus, Web of Science and CENTRAL at March 2020, and updated the search in September 2020 using relevant keywords, The data were extracted and pooled as Mean Difference (MD) with a 95% Confidence Interval (CI), using Review Manager software (version 5.4). Pooled results showed no significance between Uncorrected Distance Visual Acuity (UDVA) and Corrected Distance Visual Acuity (CDVA) between both groups underwent WFG and WFO PPR after three months follow up (MD = - 0.03; 95% CI: [-0.06, 0.00]; P = 0.07), (MD = - 0.02; 95% CI: [-0.04, 0.01]; P = 0.22) respectively. Although, no significant difference between mean manifest cylinder after three and 12 months follow up, but the total MD for mean manifest cylinder difference was significantly lower with the WFG treatment method (MD = - 0.12, (95% CI: [0.23:-0.01], P = 0.03). This shows a slight advantage of the WFG over the WFO method. The visual performance showed similarity and excellent refractive outcomes in both WFO and WFG PRK. No significant statistical differences between the two approaches. On further comparison, there was a slight advantage of the WFG over the WFO method.     

Comparison of Goldmann applanation and dynamic contour tonometry measurements: effects of corneal morphometry

ObjectivesTo compare intraocular pressure (IOP) measurements made by Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT).MethodsIOPs were measured by GAT and DCT in 63 eyes of 63 healthy subjects. A comparison was made by intraclass correlation coefficient. Passing-Bablok plot was constructed to establish the existence of systematic and/or proportional biases. Multivariate regression analysis was used to examine whether the measurements of both instruments were affected by the power of the steepest and flattest corneal axes, their orientation, age or central corneal thickness (CCT).ResultsThe intra-class correlations (ICCs) were 0.57 (95% confidence interval (95% CI): 0.29-0.74). Mean differences were 1.68 (DCT minus GAT) (95% CI: 0.92-2.44). Passing-Bablok analysis (X=DCT, Y=GAT) revealed a systematic bias (A=-14.35, 95% CI: -24.51-[-9.14]) and a proportional bias (B=1.74, 95% CI: 1.43-2.26). Multivariate regression analysis revealed that the DCT was independent of the corneal characteristics analysed while GAT was biased by CCT (B=0.042, 95% CI: 0.002-0.082).ConclusionsWhile GAT was biased by corneal CCT; DCT readings were independent of corneal morphometry.     

Corneal thickness determination and correlates in Singaporean schoolchildren

PURPOSE: To determine the central cornea thickness (CCT) in Singaporean children and to examine the possible relationship between intraocular pressure (IOP) and other biometric factors and CCT. METHODS: This was a cross-sectional study. The subjects (N=652) were obtained from the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). The subjects' ages ranged from 9 to 11 years. There were 485 Chinese, 92 Malayan, and 75 Asian Indian children. Measurement procedures included air-puff tonometry, noncontact slit lamp optical pachymetry, cycloplegic autorefraction, and autokeratometry. RESULTS: The mean CCT was 543.6 +/- 32.0 microm. Chinese children had thicker corneas than Malayan or Indian children (P=0.002). The boys had thicker corneas than girls (P=0.011), but the mean difference was only 6.4 microm. There was high correlation of CCT (r=0.98) and IOP (r=0.88) between right and left eyes. IOP was correlated with CCT (r=0.45, P <0.001). In a multiple linear regression model, each millimeter of mercury of IOP was associated with a CCT difference of 5.90 microm (95% confidence interval [CI], 4.98-6.82). The radius of corneal curvature correlated with CCT (r=0.19, P <0.001). The following parameters were not significantly (P >0.05) associated with CCT: age, family income, father's education, axial length, and spherical equivalent. CONCLUSIONS: The mean CCT in Singaporean children aged 9 to 11 years was 543.6 microm and showed ethnic and gender variation. CCT affected measured IOP and correlated weakly with corneal curvature. Compared with data in adults, a change in CCT was associated with a greater difference in measured IOP.     

Young's modulus in normal corneas and the effect on applanation tonometry.

OBJECTIVES: To determine the statistically normal range of corneal Young's modulus in young healthy eyes in vivo, and to establish if this variation has a clinically significant influence on intraocular pressure (IOP) measurement using applanation tonometry. METHODS: Central corneal curvature, central corneal thickness (CCT), and applanation IOP (Goldmann tonometer) were measured using standard clinical techniques in one eye of 100 normal human subjects (22.0 +/- 2.9 years) in vivo. The Orssengo-Pye algorithm was used to calculate the corneal Young's modulus of these experimental subjects, and to produce a theoretical model of potential errors in Goldmann applanation tonometry estimates of IOP due to variations of Young's modulus and CCT. RESULTS: Corneal Young's modulus was 0.29 +/- 0.06 MPa [95% confidence interval (CI) 0.17 to 0.40 MPa]. According to the Orssengo-Pye model, the relationship between Young's modulus and the error in applanation IOP is linear; the slope was 23 mm Hg per MPa. An increase from the minimum to the maximum value of the calculated limits of agreement (95% CI) of Young's modulus caused a variation in applanation IOP of 5.35 mm Hg. The anticipated error at the extremes of the limits of agreement (95% CI) of CCT was similar at 4.67 mm Hg. CONCLUSION: Physiological variations in corneal Young's modulus may cause clinically significant errors in Goldmann applanation tonometry estimates of IOP.     

Relationship between corneal thickness and measured intraocular pressure in a general ophthalmology clinic

OBJECTIVE: To assess whether central corneal thickness (CCT) is a confounding factor in the classification of patients attending for glaucoma assessment in a district general hospital. DESIGN: Cross-sectional study by a single observer. PARTICIPANTS: Patients attending a general ophthalmic clinic: 235 clinically normal eyes, 52 eyes with normal-tension glaucoma (NTG), 335 eyes with primary open-angle glaucoma (POAG), 12 eyes with pseudoexfoliative glaucoma (PXE), 42 eyes with chronic angle closure glaucoma (CACG), and 232 glaucoma suspect (GS) eyes. INTERVENTION: Central corneal thickness was measured using ultrasonic pachymetry. MAIN OUTCOME MEASURE: Correlation of CCT and diagnosis. RESULTS: Mean CCT was 553.9 microm (95% confidence intervals [CI] for the mean, 549.0-558.8 microm) in the clinically normal eyes, 550.1 microm (95% CI, 546.6-553.7 microm) in the POAG eyes, 514.0 microm (95% CI, 504.8-523.3 microm) in the NTG eyes, 530.7 microm (95% CI, 511.2-550.1 microm) in the PXE eyes, 559.9 microm (95% CI, 546.8-573.0 microm) in the CACG eyes, and 579.5 microm (95% CI, 574.8-584.1 microm) in the GS eyes. The differences of mean CCT between the groups were highly significant (P< 0.001 analysis of variance). Eighty-five percent of eyes with NTG and only 36% of eyes with POAG had a mean CCT of 540 microm or less. Thirteen percent of eyes with POAG and 42% of GS eyes had a mean CCT greater than 585 microm. CONCLUSIONS: The CCT measurement is desirable in patients attending for glaucoma assessment in a district general hospital to avoid misclassification resulting from the relationship between CCT and tonometric pressure. Central corneal thickness alone is not an accurate predictor for the clinical diagnosis in this group of eyes. However, many eyes diagnosed as having NTG have thin corneas, which would tend to lower the tonometrically recorded intraocular pressure (IOP), so the finding of a less-than-normal thickness cornea introduces some doubt as to the diagnosis of NTG. For the GS eyes, most eyes had thick corneas, which would tend to increase the tonometrically recorded IOP. Thus, GS eyes with modest elevation of IOP and a thick cornea may be at low risk of progressing to POAG. Thus, many patients with "high IOPs" and a thick CCT do not necessarily have high IOPs and may not need to be followed as GS eyes.     

Corneal thickness and visual field damage in glaucoma patients

PURPOSE: To verify whether there was a significant correlation between central corneal thickness (CCT) and visual field damage in patients with primary open angle glaucoma (POAG). METHODS: A total of 99 eyes with POAG were consecutively recruited. Patients were classified as glaucomatous based on visual field and optic nerve head damage. All underwent applanation tonometry, Humphrey perimetry, and measurement of CCT with ultrasonic pachymetry. Based on CCT value, the sample was split at the mode in two groups (group 1<535 microm, n=49; group 2>or=535 microm, n=50). RESULTS: Entire cohort: mean CCT 554 microm+/-45.03; mean deviation (MD) -6.68 dB+/-7.32; pattern standard deviation (PSD) 5.33+/-3.75; intraocular pressure (IOP) 17.91+/-4.16 mmHg with treatment. Group 1: CCT was 504.8 microm+/-30.8; MD -9.01 dB+/-8.72; PSD 6.38+/-3.99; IOP 18.02 mmHg+/-4.66. Group 2: mean CCT 574.6 microm+/-35.03; MD -4.39 dB+/-4.70; PSD 4.25+/-3.19; IOP 17.79 mmHg+/-3.57. A significant difference was found between the two groups for both MD and PSD. Linear regression analysis showed a significant correlation between CCT and PSD (P<0.001). CONCLUSIONS: Our data show that patients with a thinner cornea had a worse MD and PSD. As a thinner CCT causes an underestimation of the true IOP, there may be a delay in the diagnosis of POAG or an inadequate estimate of the clinical course despite apparently desirable IOP applanation readings.     

Long-term assessment of prostaglandin analogs and timolol fixed combinations vs prostaglandin analogs monotherapy

AIM: To draw a Meta-analysis over the comparison of the intraocular pressure (IOP)-lowering efficacy and safety between the commonly used fixed-combinations of prostaglandin analogs and 0.5% timolol with prostaglandin analogs (PGAs) monotherapy. METHODS: After searching the published reports from MEDLINE, EMBASE, the Cochrane Library, all randomized controlled clinical trials (RCTs) comparing the fixed combination of PGAs/timolol therapy (FCs) and PGAs monotherapy with treatment duration at least 6mo were included. The efficacy outcomes were mean diurnal IOP, percentage of participants whose IOP were lower than 18 mm Hg, incidence of visual field change, while the safety outcomes included corneal side effects, hyperemia and eye irritation. The analysis was carried out in RevMan version 5.3 software. RESULTS: After six-month medical intervention, the mean diurnal IOP of FCs was lower than PGAs (MD -1.14, 95% CI -1.82 to -0.46, P=0.001); the percentage of target IOP achieving between FCs and PGAs showed no significant difference (RR 1.18, 95% CI 0.97 to 1.43, P=0.10). No statistically significant differences of the incidence of hyperemia (RR 0.67, 95% CI 0.45 to 1.01, P=0.06) and eye irritation (RR 1.20, 95% CI 0.95 to 1.51, P=0.12) between the FCs and PGAs monotherapy were detected. Only one research involved in corneal events, result of this trial revealed no difference between two intervention groups regarding corneal effects (central endothelial cell density, MD -0.20, 95% CI -0.72 to 0.32, P=0.45; central corneal thickness, MD -0.01, 95% CI -0.02 to 0.00, P=0.23). The evaluation of visual field change was not performed due to the limited duration of the trials included in this Meta-analysis. CONCLUSION: The long-term efficacy of the FCs overweighed the PGAs monotherapy in lowering IOP, but in the incidence of hyperemia and eye irritation syndromes, the differences are not statically significant. More RCTs with detailed and authentic data over the assessments of visual functions and morphology of optic nerve heads are hoped to be conducted.     

Systematic review and Meta-analysis comparing modified cross-linking and standard cross-linking for progressive keratoconus

AIM: To compare the effectiveness and safety between modified cross-linking (MC) and standard cross-linking (SC) in mild or moderate progressive keratoconus. METHODS: Eligible studies were retrieved from four electronic databases, including CENTRAL, Clinical Trials gov, PupMed and OVID MEDLINE. We set post-surgical maximum K value (Kmax) as the primary outcome. In addition, uncorrected and corrected distant visual acuity (UDVA and UDVA), spherical equivalent (SE), endothelial cell density (ECD), central cornea thickness (CCT) and depth of demarcation line (DDL) were Meta-analyzed as secondary outcomes. Mean differences for these outcomes were pooled through either a random-effect model or fixed-effect model according to data heterogeneity. RESULTS: Twenty-four comparative studies either on accelerated cross-linking (AC) compared with SC or on trans-epithelial cross-linking (TC) compared with SC were included and pooled for analysis. The results indicated that MC was significantly inferior to SC at delaying Kmax deterioration [AC vs SC 0.49 (95% CI: 0.04-0.94, I2=75%, P=0.03); TC vs SC 1.15 (95% CI: 0.54-1.75, I2=50%, P=0.0002)]. SE decreased significantly for SC when compared to AC [0.62 (95% CI: 0.38-0.86, I2=22%, P<0.00001)]. DDL of SC was more significantly deeper than that of TC [-133.49 (95% CI: -145.94 to -121.04, I2=33%, P<0.00001)]. Other outcomes demonstrated comparable results between MC and SC. CONCLUSION: SC is more favorable at halting the progression of keratoconus, but visual acuity improvement showed comparable results between MCs and SC.     

[In Press] Systematic review and Meta-analysis comparing modified cross-linking and standard cross-linking for progressive keratoconus

AIM: To compare the effectiveness and safety between modified cross-linking (MC) and standard cross-linking (SC) in mild or moderate progressive keratoconus. METHODS: Eligible studies were retrieved from four electronic databases, including CENTRAL, Clinical Trials gov, PUBMED and OVID MEDLINE. We set post-surgical maximum K value (Kmax) as the primary outcome. In addition, uncorrected and corrected distant visual acuity (UDVA and UDVA), spherical equivalent (SE), endothelial cell density (ECD), central cornea thickness (CCT) and depth of demarcation line (DDL) were Meta-analyzed as secondary outcomes. Mean differences for these outcomes were pooled through either a random-effect model or fixed-effect model according to data heterogeneity. RESULTS: Twenty-four comparative studies either on accelerated cross-linking (AC) compared with SC or on trans-epithelial cross-linking (TC) compared with SC were included and pooled for analysis. The results indicated that MC was significantly inferior to SC at delaying Kmax deterioration [AC vs SC 0.49 (95% CI: 0.04-0.94, I2=75%, P=0.03); TC vs SC 1.15 (95% CI: 0.54-1.75, I2=50%, P=0.0002)]. SE decreased significantly for SC when compared to AC [0.62 (95% CI: 0.38-0.86, I2=22%, P<0.00001)]. DDL of SC was more significantly deeper than that of TC [-133.49 (95% CI: -145.94--121.04, I2=33%, P<0.00001)]. Other outcomes demonstrated comparable results between MC and SC. CONCLUSION: SC is more favorable at halting the progression of keratoconus, but visual acuity improvement showed comparable results between MCs and SC.     

Central corneal thickness and visual field progression in patients with chronic primary angle-closure glaucoma with low intraocular pressure

PURPOSE: To determine the association of central corneal thickness (CCT) and visual field progression in patients with chronic primary angle-closure glaucoma (CPACG) with low intraocular pressure (IOP). DESIGN: Retrospective, comparative case series. METHODS: A total of 163 eyes with CPACG and sustained IOP <18 mm Hg were included. Initial and three-year after mean deviation (MD) on Humphrey field analyzer and CCT with ultrasonic pachymetry were recorded. On the basis of the CCT value, the sample was split in two groups (group 1 <540 microm; group 2 > or =540 microm). RESULTS: Mean CCT was 525.8 +/- 11.6 microm in group 1 and 574.4 +/- 24.0 microm in group 2. There was no significant difference for initial MD (P = .979), but a significant difference was found between two groups for follow-up MD (P = .023). CONCLUSIONS: Patients with CPACG with a thinner cornea are at greater risk for visual field progression even if they maintain a low IOP after treatment.     

Pulsatile ocular blood flow during pregnancy

PURPOSE: To study pulsatile ocular blood flow (POBF) throughout pregnancy. METHODS: We enrolled twenty-seven healthy women in the first trimester of gestation, only ten of which were followed through the second trimester, and fourteen non pregnant healthy women. In each subject we measured POBF with the POBF pneumotonometer (OBF Ltd. UK), IOP, blood pressure (BP) and heart rate (HR). An unpaired Student t-test was used to compare pregnant women with non-pregnant women, and a two-tailed paired Student t-test was used to compare the same women in the first and second trimester of pregnancy. p <0.05 is considered statistically significant. RESULTS: Results are presented as means +/- SD. In the first trimester of pregnancy the age was 32 +/- 6, POBF 1516.4 +/- 382 ml/min, IOP 13 +/- 3 mmHg, BP 92 +/- 6 mmHg, and HR 86 +/- 14 beats/min. In the second trimester POBF was 1629.11 +/- 352.4 ml/min, intraocular pressure (IOP) 12 +/- 3 mmHg, BP 96 +/- 3 mmHg, and HR 93 +/- 10 beats/min. In the control group the age was 27 +/- 9, POBF 972.23 +/- 329.3 ml/min, BP 88 +/- 4.3 mmHg, and HR 80 +/- 14 beats/min. POBF increases during the first trimester (p = 0.00008). In the second trimester POBF was higher compared to the first trimester (p = 0.0008). Non significant differences were observed for the other parameters. CONCLUSIONS: The POBF increases throughout gestation. During pregnancy there is an increase in estrogen which induces endothelial-dependent vasodilatation in several tissues. The estrogen changes may influence POBF.