Central corneal thickness measurements in patients with normal tension glaucoma, primary open angle glaucoma, pseudoexfoliation glaucoma, or ocular hypertension

Design and development of a noninvasive ocular pressure estimator

SIGNIFICANCE

A snapshot intraocular pressure (IOP) is ineffective in identifying the IOP peak and fluctuation, especially during sleep. Because IOP variability plays a significant role in the progression of glaucoma, monitoring the IOP, especially during sleep, is essential to capture the dynamic nature of IOP.

PURPOSE

We aimed to design an ocular pressure estimator (OPE) that can reliably and accurately measure the IOP noninvasively over closed-eyelid condition.

METHODS

Ocular pressure estimator works on the principle that the external pressure applied by raising the IOP of the eyeball is transmitted through a compressible septum to the pressure sensor, thus recording the IOP. A fluid-filled pouch with a pressure sensor was placed over a rubber glove mimicking the eyelid (septum), covering the cornea of enucleated goat eyeballs. A pressure-controlled setup was connected to a goat cadaver eye, which was validated by a rebound tonometer. Cannulation of eyeballs through the lower limbus had the least difference from the control setup values documented using rebound tonometer, compared with cannulation through the optic nerve. Intraocular pressures ranging from 3 to 30 mmHg was induced, and the outputs recorded using OPE were amplified and recorded for 10 minutes (n = 10 eyes). We stratified the randomization of the number of times and the induced pressures.

RESULTS

The measurements recorded were found to be linear when measured against an IOP range of 3 to 30 mmHg. The device has excellent reliability (intraclass correlation coefficient, 0.998). The repeatability coefficient and coefficient of variations were 4.24 (3.60 to 4.87) and 8.61% (7.33 to 9.90), respectively. The overall mean difference ± SD between induced IOP and the OPE was 0.22 ± 3.50 (95% confidence interval, -0.35 to 0.79) mmHg across all IOP ranges.

CONCLUSIONS

Ocular pressure estimator offers a promising approach for reliably and accurately measuring IOP and its fluctuation noninvasively under a condition mimicking a closed eye.

Comparison of Ocular Biomery in Primary Open Angle Glaucoma and Non-glaucoma in South West Nigeria

Background

Glaucoma is a public health problem in Nigeria. The number of individuals affected by glaucoma in Nigeria is much higher than the individuals known to have the disease. Ocular parameters such as intraocular pressure, central cornea thickness, axial length and refractive error have all been documented as risk factors of glaucoma especially among Caucasians and African Americans, with little documentation in Africa where there's an alarming rate of blindness.

Aim and Objectives

To compare central cornea thickness (CCT), intraocular pressure (IOP), axial length (AL) and refractive state in participants with primary open angle glaucoma (POAG) and non-glaucoma in South-West Nigeria.

Materials and Methods

This hospital-based case-control study was carried out among 184 newly diagnosed POAG and non-glaucoma adult participants attending the outpatient clinic of Eleta eye institute. The CCT, IOP, AL and refractive state were measured in each participant. Test of significance between proportions in categorical variables were assessed using chi square test (χ2) in both groups. The means were compared using independent t-test while correlation between parameters were analyzed using Pearson correlation coefficient.

Results

The mean age of the POAG participants was 57.16 + 13.3 years and the mean age of the non-glaucoma participants was 54.15 + 13.4 years. The mean IOP in the POAG group was 30.2 + 8.9mmHg while non- glaucoma group was 14.2 + 2.6mmHg (P < 0.001), other ocular parameters were not significantly different in both groups. In the POAG group, decreased spherical equivalent refractive error (i.e increasing myopia) was significantly associated with increased axial length (r= -0.252, P = 0.01), but not significant in the non- glaucoma group. However, in the non-glaucoma group, central cornea thickness increased with increasing intraocular pressure (r= 0.305, P = 0.003), which was not significant in the glaucoma group.

Conclusion

Patients with POAG had much higher IOP and thus, IOP remains a significant risk factor in its development. There was a significant relationship between refractive state and axial length in the POAG group while a significant relationship was identified between central cornea thickness and intraocular pressure in the non- glaucoma group.

[Normal Tension Glaucoma]

Normal tension glaucoma (NTG) is a subvariant of primary open angle glaucoma (POAG) or a separate entity. NTG is defined as chronic open angle glaucoma without elevated intraocular pressure or normal intraocular pressure. Normal intraocular pressure is between 10 and 21 mmHg and is defined as two times the standard deviation of the mean intraocular pressure in the normal population. In addition to the absence of elevated intraocular pressure, all the classic symptoms of glaucoma are otherwise present. These include a conspicuous glaucomatous optic disc excavation, nerve fibre bundle defects, and corresponding visual field defects. Papillary rim haemorrhages are frequently found. The visual field defects in NDG are usually more central compared to POAG and are therefore described as more disturbing by the patient. The anterior chamber angle is open and there are no other changes suggestive of secondary glaucoma (pigment dispersion, pseudo-exfoliation). The exact pathophysiology of NDG is not well understood. Pathophysiologically, circulatory disturbances in the sense of arterial hypo- as well as hypertension may play an essential role or at least increase the susceptibility of the optic nerve to intraocular pressure fluctuations as well as blood pressure dips. Therefore, this requires not only a purely ophthalmologic but also interdisciplinary treatment of the patient with confirmed NDG. The primary goal of treatment is the reduction of intraocular pressure, which can stop the disease. This article gives an overview of epidemiology, aetiology, clinical findings and therapies.

Normaldruckglaukome

Das Normaldruckglaukom wird definiert wird als primär chronisches Offenwinkelglaukom, bei dem kein erhöhter Augeninnendruck vorliegt. Trotz normalem Augeninnendruck ist das primäre Ziel der Behandlung die Augeninnendrucksenkung, mit der es gelingen kann, die Erkrankung aufzuhalten. Dieser Artikel soll eine Übersicht über Epidemiologie, Ätiologie, Pathogenese, klinische Befunde sowie Therapien geben.

Central Corneal Thickness Among Filipino Patients in an Ambulatory Eye Surgery Center Using Anterior Segment Optical Coherence Tomography

Objective

The purpose of the study was to determine the central corneal thickness (CCT) among Filipino patients that may contribute to different glaucoma diagnosis using the anterior segment optical coherence tomography in an ambulatory eye surgery center.

Methods

A single-center retrospective, cross-sectional study design including 1232 eyes of 641 patients of the Asian Eye Institute, Makati, Philippines from January 2019 to December 2019 who had their CCT measured with Visante anterior segment optical coherence tomography (AS-OCT). CCT was correlated with age, sex, presence of diabetes and/or hypertension, and glaucoma diagnosis.

Results

Among 641 patients who had their CCT measured by Visante AS-OCT, 723 eyes of 369 patients were included. Nearly half of the study population were normal or glaucoma suspects. The mean CCT among Filipino patients was 535.59 ± 34.06 µm. Ocular hypertensive patients had the thickest CCT, while normal tension glaucoma patients had the thinnest CCT. After adjusting for multiple variables, CCT had a direct relationship with the presence of diabetes, IOP level and the diagnosis of ocular hypertension, while inverse relationship with age. Most of the patients presenting with angle closure glaucoma were females aged 60 and above.

Conclusion

Visante AS-OCT is a non-contact and non-aerosol generating instrument allaying the fear of disease transmission from contact or aerosolization of tears. Our study confirms similar relationships of CCT with age, presence of diabetes, IOP level, and diagnosis of ocular hypertension or normal tension glaucoma among Filipino patients with the available literature from other ethnicities.

The evaluation of juvenile ocular hypertension by optical coherence tomography angiography

Background

Vessel density (VD) of the elderly ocular hypertension patients measured by optical coherence tomography angiography (OCTA) have been reported. However, the studies of VD in juvenile ocular hypertension (JOHT) are limited. We wished to evaluate VD changes using OCTA in JOHT. We also investigated the potential risk parameters of intraocular pressure (IOP) and vertical cup/disc ratio (CDR) with OCTA for observing the development of JOHT.

Methods

We examined 86 eyes in 45 control (Ctrl) subjects and 65 eyes in 34 patients with JOHT using OCTA at the glaucoma clinic of the Eye, Ear, Nose, and Throat Hospital of Fudan University. The VD of radial peripapillary capillaries (RPC) and the perifoveal superficial vascular plexus (SVP) was compared between the Ctrl and JOHT groups. Other basic study factors such as age, sex, blood pressure, best-corrected visual acuity, central corneal thickness, IOP, CDR, the thickness of the retinal nerve fiber layer, ganglion cell complex, visual field mean deviation, and pattern standard deviation were also recorded.

Results

Bare difference was found in the nasal-inferior and temporal RPC-VD between the Ctrl and JOHT groups (P = 0.042 and P = 0.033, respectively) while SVP-VD was not (all P > 0.05). In the mixed linear regression model analysis, temporal RPC-VD was marginally negatively associated with high IOP (r = − 1.379, P = 0.043). Five additional sections of nasal, inferior-nasal, inferior-temporal, superior-temporal, and superior-nasal RPC-VD showed positive correlation with large CDR (all P <  0.05). SVP-VD in the superior and nasal regions was marginally negatively correlated with high IOP (r = − 1.877, P = 0.023; r = − 1.693, P = 0.049). No other regions were found statistical different of relationship between IOP, CDR and VD.

Conclusions

Nasal-inferior and temporal peripapillary VD was marginally lower in JOHT subjects. Regarding parameters of IOP and CDR, peripapillary temporal VD had a borderline level of negative correlation with IOP more than 21 mmHg while additional five regions were strongly positively correlated with large CDR. Some macular regions only found marginal positive correlation with parameter of high IOP. We conclude that OCTA can be used as a potential technique to evaluate the VD in JOHT and peripapillary scans should be analyzed individually based on different levels of CDR.

High-throughput 3D bioprinting of corneal stromal equivalents

In this study we designed high-throughput 3D bioprinting of corneal equivalents which may address the need for in vitro models. In our digital 3D cornea model, average dimensions of adult cornea were converted to 3D shapes, then to G-code files which were printed by BIOX printer (CELLINK). To maintain the curvature of cornea, a support scaffold was designed using stereolithographic printer. The support scaffold could facilitate the printing of 6-12 corneas at a time thus enabling high-throughput printing. Human corneal keratocytes (HCKs) were incorporated in the optimized bio-ink, and cell-laden corneal stromal equivalents were printed. Printed structures were cross-linked by calcium chloride 100 mM, washed with Hanks' Balanced Salt Solution and incubated at 37°C in fibroblast media. Printed corneas were analyzed for live dead assay, Alamar assay, and expression of fibronectin and actin green markers. Printed corneas were able to maintain their structure, integrity, and clarity. Live dead assay and Alamar assay demonstrated that HCKs maintained high viability (>95%) for 2 weeks. HCKs in the printed corneas showed expression for fibronectin and actin green. In conclusion, high-throughput fabrication of 3D printed corneal stromal equivalents using a combination of stereolithography printing, extrusion based printing, and micro-transfer molding techniques was achieved.

Tele-glaucoma versus clinical evaluation: The New Jersey Health Foundation Prospective Clinical Study

INTRODUCTION

Glaucoma, the second most common cause of blindness, is normally detected in clinic. With technological improvements, tele-glaucoma exams can identify these changes off-site. The quality of tele-glaucoma exams needs to be compared with that of traditional exams. This study's purpose was to validate the tele-glaucoma programme, which allows a physician comprehensive access to patients' data, by comparing results to clinical examinations.

METHODS

A prospective study of 107 subjects evaluated in clinic and then tele-glaucoma stations, which consisted of non-mydriatic fundus photography, puff-tonometry, auto-refraction and Optical Coherence Tomography (OCT). The OCT captured central corneal thickness, angle anatomy, cup-to-disc ratio (CDR), retinal nerve fibre layer distribution and posterior-pole ganglion cell complex data.

RESULTS

Intraocular pressure (IOP) comparisons between clinical and tele-glaucoma exams had strong positive Pearson correlation coefficients (0.8248 OD, 0.8672 OS). Strong positive correlations were seen for CDR (0.7835 OD, 0.8082 OS) as well as diagnosis (glaucoma, no glaucoma or glaucoma suspect). A moderate positive correlation was seen for return to clinic time (RTC). Tele-glaucoma had an average lower RTC (2.7 vs 3.9 months). Tele-glaucoma was more likely to elicit a non-glaucomatous diagnosis not found in clinic vs a diagnosis found only in clinic (18% vs 5% of subjects).

DISCUSSION

Tele-glaucoma allows for detecting glaucoma remotely. These advancements alleviate patient difficulties with obtaining adequate glaucoma screenings and helps ophthalmologists triage patients with more severe pathology. Our study indicates that our tele-glaucoma protocol is comparable to a clinical exam in its ability to detect glaucoma. Further studies will be needed for off-site testing and transferring data separately for analysis.

Corneal biomechanical changes after trabeculectomy with mitomycin C in primary open-angle glaucoma and pseudoexfoliation glaucoma

PURPOSE

This study aimed to examine the effect of trabeculectomy with mitomycin C on corneal biomechanical characteristics in PEXG and POAG patients.

METHODS

In this prospective comparative case series study, 32 glaucoma patients of whom 17 patients were suffering from PEXG and 15 patients from POAG were enrolled. All patients underwent complete ocular examination, CCT using ultrasound pachymetry and corneal biomechanical study using ORA. The patients were hospitalized, and trabeculectomy surgery with mitomycin was done. Three months after surgery, patients were examined and ORA was obtained again.

RESULTS

The mean CH in patients with PEXG was lower compared to patients with POAG (5.66 ± 1.13, 7.49 ± 0.88, respectively) before surgery, which had a statistically significant difference (P < 0.001). CRF in patients with PEXG was significantly lower compared to patients with POAG (8.19 ± 1.48 vs. 9.35 ± 1.60, respectively) before surgery, with P = 0.049. CH remarkably increased and reached 6.69 ± 0.78 (P < 0.001) in the PEXG group after TBX + MMC surgery. CH increased in the POAG group after TBX + MIC surgery and reached 8.23 ± 1.09, which was statistically significant (P = 0.001). There was a significant relationship between CH and IOP_g changes in both PEXG and POAG groups (P < 0.001 and P = 0.01, respectively). Although TBX + MMC surgery changed the amount of CH in PEXG and POAG groups, no significant difference was shown in the parameters between the two groups comparing the CH changes (P = 0.33).

CONCLUSION

According to the results of this study, the biomechanical characteristics of cornea, particularly CH, shows certain changes following surgery and is increased, reflecting the dynamic nature of these parameters. Our knowledge of the biomechanical changes after glaucoma surgery can help us better understand the pathophysiology of glaucoma diseases and make the right decisions for follow-up of the patients.

Distribution of central corneal thickness and intraocular pressure in emmetropic eyes of healthy children of Palestine: a representative cross-sectional study

AIM

To determine the distributions of central corneal thickness (CCT) and intraocular pressure (IOP) in emmetropic eyes of healthy children of Palestine.

METHODS

This representative cross sectional study included a total of 1156 eyes from 578 healthy school children aged 7-15y. Inclusion criteria included emmetropia, no previous history of ocular or systemic diseases, no previous history of contact lens use, and the availability of both eyes. CCT and IOP were measured using ultrasound pachymeter and Goldmann applanation tonometer, respectively. The relationship of the results with age and gender was investigated.

RESULTS

The mean age of school children was 11.13±2.8y. Mean CCT was 542.2±37.4 and 544.3±39.2 µm for right and left eyes, respectively. Mean IOP was 12.5±2.2 and 12.3±2.2 mm Hg for right and left eyes, respectively. A positive correlation was observed between CCT and IOP of the right eye (P<0.001, R=0.358) and CCT and IOP of the left eye (P<0.001, R=0.324). No significant differences were observed in CCT and IOP due to age or gender (P>0.05). There were significant differences in mean CCT and IOP between right and left eyes (P=0.004, P=0.001, respectively).

CONCLUSION

A population profile of CCT and IOP is established in Palestinian children for the first time. Mean CCT is comparable to some studies but differ from others. Mean IOP is considerably lower than that of majority children of other ethnic groups. Intereye difference of more than 36 µm in CCT, and 5 mm Hg in IOP should prompt evaluation for potential ocular disorders.

Evaluation of Anterior Segment Parameters in Pseudoexfoliative Glaucoma, Primary Angle-Closure Glaucoma, and Healthy Eyes

Objectives:

To evaluate anterior segment parameters measured by dual Scheimpflug corneal topography in pseudoexfoliative glaucoma (PEXG), primary angle-closure glaucoma (PACG), and healthy eyes.

Materials and Methods:

One hundred forty-three eyes of 86 patients were included in this study. Forty-seven eyes of 38 patients with PEXG, 30 eyes of 15 patients with PACG, and 66 eyes of 33 healthy subjects were evaluated. Patients who underwent previous ophthalmic surgery and contact lens wearers were excluded. After full ophthalmological examination, mean central corneal thickness (CCT), white-to-white horizontal corneal diameter (WTW), pupillary diameter (PD), anterior chamber volume (ACV), anterior chamber depth (ACD), and mean anterior chamber angle were measured by dual Scheimpflug corneal topography and compared between the three groups. Statistical analyses were done using Statistical Package for Social Sciences for Windows 18.0 program.

Results:

No statistical difference was found in mean age or gender among the study groups (p>0.05). There were also no statistical differences in CCT, WTW, or PD among the groups (p=0.568, p=0.064, p=0.321, respectively). ACV, ACD, and mean anterior chamber angle values were significantly lower in the PACG group compared to the other groups (p=0.000 for all). There was no statistically significant difference in these measurements between the PEXG and normal eyes.

Conclusion:

ACV and depth and mean anterior chamber angle were statistically different (lower) in PACG when compared with PEXG and healthy eyes. Dual Scheimpflug corneal topography can be used as an objective method for the measurement of anterior segment parameters in glaucoma.

Ocular and Systemic Risk Factors and Correlation with Glaucomatous Damage in Normal Tension Glaucoma

Background

Normal tension glaucoma (NTG) is a clinical entity that poses a diagnostic and therapeutic challenge. The study elaborates ocular and systemic risk factors of NTG in the South Indian population. It determines the correlation between risk factors and severity of glaucomatous damage.

Methods

This descriptive study was done on 81 eyes of 41 patients. A brief history of hypertension, heart disease, migraine, and family history of glaucoma were noted. The parameters measured include blood pressure, lipid profile, visual acuity, refraction, intraocular pressure (IOP) by applanation tonometry, diurnal variation, slit lamp biomicroscopy, central corneal thickness (CCT), and perimetry (Humphrey 24-2).

Results

The mean age was 51.75 years. There was female predilection (63.41%). Thirteen patients (32.5%) had hypertension, five (12.5%) had migraine, and seven had hyperlipidemia (17.5%). Perfusion pressure demonstrated a negative correlation value of -0.319 (rho value) with visual field defects (p<0.05) and -0.266 (rho value) with glaucomatous cupping (p=0.093). The IOP varied from 10 mmHg to 19 mmHg with a mean of 15.34. The average CCT was 522.06±36.09 microns. Neuroretinal rim thinning was seen in 12 eyes (14.8%), polar notching in six eyes (7.4%), and peripapillary atrophy in 20 eyes (24.6%). Two eyes (2.4%) had splinter hemorrhage at disc margin. A lower value of CCT was associated with lower IOP, a weak positive correlation (r value 0.121). Optic disc cupping is strongly associated with severity of field defects, r value 0.743, (p<0.00).

Conclusion

Normal tension glaucoma is common in females. Hypertension and lower diastolic perfusion pressure are important risk factors. Lower CCT is associated with lower IOP (applanation tonometry). Optic disc cupping and diastolic perfusion pressure strongly correlate with severity of visual field defects.

Correlation Between Dynamic Contour Tonometry, Uncorrected and Corrected Goldmann Applanation Tonometry, and Stage of Glaucoma

Importance

Accurate determination of intraocular pressure (IOP) is crucial for the diagnosis and management of glaucoma. Objective clinical evaluation of the correction equations for Goldmann applanation tonometry (GAT) is lacking.

Objectives

To investigate the difference between corrected and conventional GAT and Pascal dynamic contour tonometry (DCT) measurements, as well as the correlation between discordant IOP values and stage of glaucoma.

Design, Setting, and Participants

This prospective cross-sectional case series was conducted at the Department of Ophthalmology, University Hospital Zurich, and Talacker Eye Center between July 1, 2011, and May 31, 2016, among 112 white patients with glaucoma.

Interventions

Intraocular pressure measurements were performed with GAT and DCT in a randomized order. Goldmann applanation tonometry measurements were modified with 5 correction equations.

Main Outcomes and Measures

The primary end point was degree of concordance between corrected or uncorrected GAT and DCT measurements. The secondary end point was association between discordant IOP measurements and the stage of glaucoma, as assessed by the Glaucoma Severity Score.

Results

Among the 112 patients (67 women and 45 men; mean [SD] age, 66.3 [13.1] years), 63 of the eyes in the study (56.3%) were left eyes and 85 patients (75.9%) were taking ocular antihypertensive medications. Mean (SD) IOP was 20.3 (4.5) mm Hg (95% CI, 19.4-21.1) as measured by DCT and 17.0 [4.1] mm Hg (95% CI, 16.3-17.8) as measured by GAT. The mean (SD) discordance between DCT and GAT measurements was -3.3 (2.0) mm Hg (95% CI, 2.9-3.6). The 5 corrected GAT values ranged from -2.7 to -5.4 mm Hg compared with DCT. The mean (SD) result of the Dresdner correction formula (17.6 [4.1] mm Hg) was closer to the DCT measurement than the original GAT measurement. The mean (SD) Glaucoma Severity Score was 4.7 (3.4) (95% CI, 4.1-5.4). The uncorrected discordance IOPDCT - IOPGAT showed a positive correlation with the Glaucoma Severity Score (rs = 0.33; P < .001) and a negative correlation with central corneal thickness (rs = -0.22; P = .02).

Conclusions and Relevance

In comparison with DCT measurements, these data suggest that GAT values are significantly discordant in eyes with thin corneas and advanced glaucoma. Application of GAT-based correction formulas involves a possible risk of creating an even greater number of unpredictable measurement errors. Hence, we advise with caution, especially pertaining to eyes with thin corneas, to not place reliance on GAT readings, and abandon any correction formula.

Trial Registration

clinicaltrials.gov Identifier: NCT01474070.

No differences in central corneal thickness between open-angle and pseudoexfoliation glaucoma patients

Introduction

Measurements of intraocular pressure (IOP) with Goldmann applanation tonometry are affected by central corneal thickness (CCT), as thinner corneas underestimate and thicker corneas overestimate the true IOP value. The literature is controversial regarding CCT values in patients with primary open-angle glaucoma (POAG) and exfoliation glaucoma (XFG). The aim of this study was to evaluate CCT in patients with XFG and POAG.

Methods

CCT was evaluated with optical coherence tomography (OCT). All participants who were previously diagnosed with either POAG or XFG underwent ophthalmological examinations. Contact lens users and patients with corneal diseases were excluded.

Results

Totally, 145 patients were enrolled in this study. The mean CCT was 535±30.4 µm in patients with POAG and was 536±33.7 µm in patients with XFG. The result was not statistically significant (P=0.98). The mean age for all participants was 73.8±7.7 years. The study included totally 61 women and 84 men. The two groups were similar in their demographic data, and mean deviation was the only parameter that differed statistically when comparing POAG with XFG (P=0.02).

Conclusion

Our data indicate that patients with XFG do not have thinner corneas than those with POAG, and therefore, CCT can not explain why they progress differently.

Central corneal thickness in newly diagnosed glaucoma patients in South West Ethiopia: a cross-sectional study

Background

Reports of central corneal thickness (CCT) among glaucoma patients, particularly for pseudoexfoliative glaucoma (PXG) and Primary Angle Closure Glaucoma (PACG) are scarce in the Sub-Saharan African (SSA) population. The aim of this study is to evaluate CCT in black patients with newly diagnosed glaucoma and ocular hypertension (OHT) in South West Ethiopia.

Methods

This was a prospective study undertaken with an ultrasonic pachymeter from June 2014 to February 2015 in Jimma University Specialized Hospital. Patients aged 18 years and older newly diagnosed with glaucoma or OHT were included.

Results

A total of 162 eyes of 162 subjects were included. Hundred and fifty five subjects were glaucomatous: (67 PXG, 42 Primary Open Angle Glaucoma (POAG), 28 PACG, 14 Normal Tension Glaucoma (NTG), 5 Juvenile Open Angle Glaucoma (JOAG) and 6 (OHT). The mean age was 59.3 ± 12.8 years.

For the whole sample, CCT was 518.67 (±39.97) μm. OHT group had significantly greater CCT (576.33 ± 49.32 μm) than the glaucomatous groups (p = 0.004). POAG (506.69 ± 35.08 μm) and NTG (510.79 ± 44.37 μm) groups had thinner CCT than PXG (520.48 ± 38.95 μm), PACG (524.00 ± 37.16 μm), and JOAG (518.00 ± 30.82 μm) groups, but this was not statistically significant (p = 0. 296). There was a statistically significant decline of CCT with advanced age (P = 0.02). There wasn’t significant difference of average CCT between the ethnic groups (P = 0.3) and gender (P = 0.064).

Conclusion

The mean CCT of Ethiopian glaucoma patients is thinner than Caucasians and similar to those reported from previous studies in Sub Saharan Africa. OHT patients had thicker CCT; there was no statistically significant difference observed in average CCT amongst glaucoma subtypes.

The Effect of Pseudoexfoliation and Pseudoexfoliation Induced Dry Eye on Central Corneal Thickness

PURPOSE/AIM OF THE STUDY

The aim of this study is to investigate the effect of pseudoexfoliation (PEX) and PEX-induced dry eye on central corneal thickness (CCT).

MATERIALS AND METHODS

This cross-sectional study consists of total 270 eyes of 135 patients (67 females, 68 males) in total. After excluding the PEX (-) 32 eyes with PEX in the other eye, totally 130 eyes in PEX (-) group and 108 eyes in the PEX (+) group were included in the study. The PEX (+) group was regrouped as PEX syndrome (80 eyes of 50 patients) and PEX glaucoma (28 eyes of 20 patients).

RESULTS

In the PEX (-) group, the mean Schirmer test result was 12 ± 4 mm (4-25 mm), in the PEX syndrome group 10 ± 4 mm (4-22 mm), in the PEX glaucoma group 9 ± 3 mm (4-15 mm). The difference among the PEX (-) group, the PEX syndrome and the PEX glaucoma groups was statistically significant (p < 0.001, p < 0.001, respectively). In the PEX (-) group, the mean tear break up time test result was 11 ± 2 s (5-16 s), in the PEX syndrome group 8 ± 3 (3-16 s), in the PEX glaucoma group 8 ± 3 s (5-15 s). Mean CCT result was 544 µm in the PEX (-), 521 µm in the PEX syndrome group and 533 µm in the PEX glaucoma group. The difference among the PEX (-) group, the PEX syndrome and the PEX glaucoma groups was significant (p < 0.001, p = 0.030, respectively). There was a significant (+) correlation between intraocular pressure and CCT in the eyes with PEX (r = 0.307, p = 0.001). However, there was no statistically significant correlation between CCT, Schirmer and tear break up time tests in the eyes with PEX.

CONCLUSIONS

PEX material can cause decrease in tear film secretion and disturb tear film stability. There is no effect of PEX-induced dry eye on CCT. Lower CCT values in the eyes with PEX material may be a result of decrease in corneal stromal cell density. Moreover, higher CCT values may be because of decreased endothelial cells in PEX glaucoma patients.

Central corneal thickness in primary angle closure and open angle glaucoma

Purpose:

To quantitatively analyze central corneal thickness (CCT) in patients with primary angle closure glaucoma (PACG) and primary open-angle glaucoma (POAG), and to evaluate its correlation with severity of glaucoma.

Methods:

In this retrospective study, records of patients with previously diagnosed POAG or PACG at a tertiary glaucoma service were reviewed. CCT was measured by ultrasound pachymetry. Mean deviation (MD) on visual field (VF) testing was recorded for glaucoma severity determination. CCT and age- and sex-adjusted CCT were compared among the study groups using Student's t-test and analysis of covariance (ANCOVA), respectively. Univariate and multivariate regression models were used for correlation of age, MD and CCT.

Results:

A total of 115 patients with PACG, 215 with POAG, and 100 normal controls were included with mean age of 64.1 ± 10.4, 59.9 ± 10.5, and 62.04 ± 10.80 years, respectively. CCT was thicker in PACG eyes (545.5 ± 46.1 μm) as compared to POAG eyes (531.7 ± 37.3 μm) and controls (531.0 ± 38.3 μm) even after age and gender adjustment (ANCOVA, P = 0.05). CCT was found to decrease with increasing age only in the POAG group (β = -0.57, P = 0.01). Disease severity (MD of VF) was significantly and inversely correlated with CCT in both POAG and PACG eyes (β = 1.89, P = 0.02; and β = 1.38, P = 0.04, respectively) after age and sex correction.

Conclusion:

PACG eyes had thicker CCT as compared to POAG and normal healthy eyes in Iranian subjects. Severity of the disease was inversely correlated with CCT in eyes with both POAG and PACG.

Comparison study of OCT, HRT and VF findings among normal controls and patients with pseudoexfoliation, with or without increased IOP

PURPOSE

To compare and evaluate optic nerve head (ONH) and retinal nerve fiber layer (RNFL) measurements obtained with the optical coherence tomography (OCT) and the Heidelberg retina tomography (HRT) to visual field (VF) parameters in normal and in patients with pseudoexfoliation with or without increased intraocular pressure (IOP).

METHODS

A total of 96 subjects were included in our study aged between 65 years and 78 years. The normal group consisted of 28 subjects (14 men and 14 women). Out of the total number of patients, 68 patients who showed pseudoexfoliation (21 men and 47 women) were divided into two groups. Of these, the first group had pseudoexfoliation with increased IOP and the second group showed deposits of pseudoexfoliative material without an increase in IOP. The normal controls were randomly chosen and restricted to those without any glaucomatous optic disc damages, VF defects, and an IOP <15 mmHg. All subjects were prospectively included for repeated measurements of IOP, OCT, HRT, and VFs during the same visit by the same examiner and all measurements were repeated every 3 months.

RESULTS

Mean RNFL thickness measured by OCT was larger in the normal controls than in the other two groups (98.04 μm (first group) vs 75.42 μm and 97.02 μm (second group), P<0.05). Four-quadrant RNFL thickness measurements were significantly different between the normal and the group 1 (P<0.05) but not with the group 2 (P>0.05). Rim area had a mean difference of -0.44, whereas cup-to-disc ratio (C/D) showed a mean difference of 0.31, thus being significantly different between the normal and the two groups (all P<0.05). The median of the mean deviation parameter of VFs was -0.28 for the normal vs -0.32 and -0.18 for the other two groups, whereas pattern standard deviation median difference was 0.89 for the normal and 1.32 and 1.20 for the other two groups, respectively (P<0.05).

CONCLUSION

Both OCT and HRT showed early ONH and RNFL changes in their parameters and did not correlate with the normal findings of the automated perimetry.

Cornea in PCOS patients as a possible target of IGF-1 action and insulin resistance

OBJECTIVES

Previous studies suggest that serum IGF-1 is higher in women with polycystic ovary syndrome (PCOS). The ophthalmologic effects of IGF-1 excess have not yet been investigated in women with PCOS. The aim of the current study is to compare the corneal thickness of patients with PCOS and those of healthy subjects.

METHODS

Forty three patients with PCOS and 30 age-matched and gender-matched healthy individuals were enrolled in this cross-sectional study. Central corneal thickness (CCT) was measured in patients with PCOS and in healthy individuals with an ultrasound pachymeter. IGF-1 values were also determined in the study group.

RESULTS

Women with PCOS had significantly higher levels of IGF-1 and homeostasis model assessment (HOMA-IR) levels than the control group. Right and left CCT measurements were higher in the PCOS group than in the control group. A positive correlation between IGF-1 and right and left CCT was identified in both groups. In multiple linear stepwise regression analyses, IGF-1 independently and positively associated with HOMA-IR in women with PCOS. A correlation between total testosterone and CCT was identified in the whole group. In multiple stepwise regression analyses, total testosterone independently and positively associated with left central corneal thickness in the whole group.

CONCLUSIONS

These findings indicate that PCOS has target organ effects on the eye. Consequently, it can change central corneal thickness. Higher IGF-1 levels seem to be the main causes of increased corneal thickness. Insulin resistance in PCOS is one of the underlying causes and promotes increase in IGF-1. We suggest a careful and detailed corneal evaluation in PCOS patients to prevent the potential risk of increased CCT, in addition to the already-known complications.

Evaluation of the endothelial cell density and the central corneal thickness in pseudoexfoliation syndrome and pseudoexfoliation glaucoma

Purpose. Evaluation of central corneal thickness (CCT) and endothelial cell density (ECD) in patients with senile cataract and coexisting pseudoexfoliation (PEX) syndrome with glaucoma (PEXG) and without glaucoma using specular microscopy. Participants and Methods. The study included 122 patients (217 eyes). In this group of patients we identified 133 eyes with PEX syndrome (65 with glaucoma, 68 without glaucoma) and 84 eyes without PEX syndrome. ECD and CCT were measured in each eye by specular microscopy. Results. ECD in eyes with PEX syndrome without glaucoma (2297 ± 359 cell/mm²) and in eyes with PEXG (2241 ± 363 cell/mm²) was lower than in the control group (2503 ± 262 cell/mm²) (P < 0.001). CCT in eyes with PEXG (508.2 ± 32.6 μm) was thinner than in eyes with PEX syndrome without glaucoma (529.7 ± 30.3 μm) and control group (527.7 ± 29.4 μm) (P < 0.001). Conclusions. This research shows that in eyes with PEX syndrome, both with and without glaucoma, ECD was statistically significantly lower than in the control group. In patients with PEXG, CCT was statistically significantly thinner than in the PEX syndrome and control group.

The central corneal thickness in normal tension glaucoma, primary open angle glaucoma and ocular hypertension

AIMS AND OBJECTIVES

To compare the Central Corneal Thickness (CCT) of Normal Tension Glaucoma (NTG) with those of Primary Open Angle Glaucoma (POAG) and Ocular Hypertension (OHT) and to study the effect of CCT on the diagnosis and management of glaucoma patients.

METHOD

A total of 99 patients [35(35.35%) females and 64(64.65%) males] were included in the study with four study groups-37 controls (males-24 and females-13), 22 NTG (males-11 and females-11), 28 POAG (males-21 and females-7), and12 OHT (males-8 and females-4). The CCTs of all the participants were measured by using ultrasonic pachymetry. The IOPs were measured by using applanation tonometry. The measured IOPs were corrected by using a linear correction formula. The measurement significant changes (>=1.5) and outcomes significant changes (>=3.0) for the study groups were calculated.

RESULTS

The mean CCT of the normals was 527.65± 21.90 μ, the mean NTG was 503.91 ± 11.31 μ, the mean POAG was 525.25± 23.59 μ and the mean OHT was 572.25± 22.71 μ. The difference which was observed in the mean CCT among the groups was statistically significant (p<0.05). The measurement significant change (>=1.5) after correcting the IOP for CCT was observed in 32.258% of the total glaucoma patients, with 27.3% patients ( 6 out of 22) in the NTG, 66.7% patients (8 out of 12) in the OHT and 21.4% patients ( 6 out of 28) in the POAG groups showing it. The difference which was observed was statistically significant (p<0.05). The outcomes significant change (>=3.0) after correcting the IOP for CCT was seen in 6.45% of the total glaucoma patients, with none of the NTG group patients showing outcomes significant changes, whereas 3.57% patients (1out of 28) in the POAG and 25% patients ( 3out of 12) in the OHT groups showed these changes. The difference which was observed was statistically significant (p<0.05).

CONCLUSION

This study confirmed that the central corneal thickness was significantly lower in the normal tension glaucoma patients as compared to those in the controls and in the primary open angle glaucoma patients, whereas the ocular hypertension patients had significantly higher central corneal thicknesses than the controls and the primary open angle glaucoma patients. No significant difference was found between the primary open angle patients and the controls. Due to the effect of CCT on the measurement of the IOP by using an applanation tonometer, which is the main parameter in the diagnosis and the follow up of the glaucoma patients, many POAG patients are misdiagnosed as NTG patients and the normals are misdiagnosed as OHT patients and they are improperly managed. Measurement of the central corneal thickness aid the ophthalmologist in making a correct diagnosis and in a better management of glaucoma and the glaucoma suspects, especially when their corneal thickness differs markedly from the normal thickness.

Is there a relationship between sleep apnea and central corneal thickness?

PURPOSE

The objective of this study was to determine the central corneal thickness (CCT) measurements in patients with Sleep Apnea Syndrome (SAS) and the relationship between the severity of SAS and minimal arterial oxygen saturation (min. SpO2) with respect to CCT.

MATERIALS AND METHODS

Two hundred and fourteen eyes of 107 patients (58 males, 49 females) who were diagnosed as SAS and 80 eyes of 40 healthy subjects (20 males, 20 females) were included in the study. The SAS patients were divided into subgroups according to their Apnea-Hypopnea Index (AHI) values as: AHI values between 5 and 15 as subgroup 1, between 15 and 30 as subgroup 2, and the values ≥30 as subgroup 3. The CCT was measured by an ultrasonic pachymetric system. Statistical analyses were an analysis of variance test and, for post-hoc analysis, the Dunnett C test.

RESULTS

Mean age was 52.5 ± 10.96 years in the study group, and 40.7 ± 10.14 years in the control group. There were 58 (54.2%) males and 49 (45.8%) females in the study group, and 20 (50%) males and 20 (50%) females in the control group. Mean CCT values were 526.65 ± 25.06, 525.26 ± 29.25, 512.93 ± 43.20 and 539.90 ± 17.28 in subgroup 1, subgroup 2, subgroup 3 and the control group, respectively. There were no statistically significant differences between gender and age groups with respect to CCT (p > 0.05). When the mean CCT values of each subgroups were compared with the control group, the differences were statistically significant (p < 0.05). There was a negative correlation between CCT and AHI values and a positive correlation between CCT and min. SpO2 values.

CONCLUSIONS

CCT measurements differ significantly in patients with SAS compared with healthy control subjects. It should be taken into consideration that SAS may reduce CCT over time and that CCT should be measured in each ophthalmic examination.

The impact of central corneal thickness on intraocular pressure among Ethiopian glaucoma patients: a cross-sectional study

Background

Raised intraocular pressure (IOP) is the only causal risk factor for glaucoma that can be therapeutically manipulated to change the course of the disease process. Though Goldman applanation tonometry (GAT) is the “gold standard” for IOP measurement, readings of IOP with GAT are affected by central corneal thickness (CCT). The aim of this study is to determine the impact of CCT on IOP among Ethiopian glaucoma patients.

Methods

It was a multicenter cross-sectional study and all glaucoma patients visiting their respective eye clinic during the study period were included. A total of 199 randomly selected glaucomatous eyes from 199 patients aged 18 years and above were employed. The CCT was measured by OcuScan™ RxP Ophthalmic Ultrasound and IOP was measured with Goldmann applanation tonometer. Linear regression and bivariate correlation analysis were carried out and level of significance was taken at 5%.

Results

The mean IOP was 19.46(±7.05) mmHg and mean CCT was 508.07(±33.26) μm. The mean IOP for primary open angle glaucoma (POAG), ocular hypertension (OHT), normal tension glaucoma (NTG), pseudoexfoliative glaucoma (PXG) and primary chronic angle closure glaucoma (PCAG) patients was 19.22 mmHg, 21.39 mmHg, 14.33 mmHg, 33.25 mmHg and 14.75 mmHg respectively. The mean CCT values were 502.24 μm (POAG), 524.32 μm (OHT), 500.75 μm (NTG), 579.00 μm (PXG) and 530.25 μm (PCAG). Age of the patient and glaucoma surgery had an influence on corneal thickness. A positive relationship was found between CCT and IOP (p < 0.001).

Conclusions

The mean CCT of Ethiopian glaucoma patients is thin in comparison to other ethnic groups and patients with OHT have thicker corneas than POAG patients. Hence determination of CCT for each patient is necessary in the up-to-date glaucoma management.

Central corneal thickness and corneal curvature in pseudoexfoliation syndrome with and without glaucoma

PURPOSE

To determine the central corneal thickness (CCT) and corneal curvature (CC) in pseudoexfoliative (PE) eyes with and without glaucoma.

METHODS

Charts of 551 consecutive patients undergoing preoperative examinations for cataract surgery between April 2006 and May 2009 in our clinic were reviewed retrospectively. Fourty-eight PE patients (48 eyes; 19 with glaucoma, 29 without glaucoma) and 48 age-matched and sex-matched control patients were enrolled in the study. The CCT, CC, intraocular pressure, and axial length were measured by ultrasonic pachymeter, autorefractokeratometer, Goldmann applanation tonometry, and ultrasound biometry, respectively. The independent samples t test and paired samples t test was used for the comparisons of the groups.

RESULTS

Mean CCT was significantly thinner in all PE and nonglaucomatous PE (Pseudoexfoliation syndrome "PES") eyes than in control eyes (P=0.004 and P=0.005, respectively). There was no difference in CCT between PE glaucoma (PEG) and control eyes (P=0.089). There was no difference in mean keratometry (K) and axial length in the study and control groups. In 22 unilateral PE eyes, mean CCT and K readings were insignificant between the PE eyes and fellow non-PE eyes.

CONCLUSIONS

CCT was significantly thinner in eyes with PES compared with control eyes; however, difference between the PEG and control eyes was insignificant. In addition, mean K readings were not different in study and control eyes. Thinner CCT in eyes with PES, both as it is an independent risk factor and as a result of artificially lower intraocular pressure readings, may be an illuminating cause for development and rapid progression of glaucoma in the patients with PES.

Central corneal thickness in Chinese subjects with primary angle closure glaucoma

PURPOSE

To characterize central corneal thickness (CCT) in Chinese eyes with primary angle closure glaucoma (PACG).

METHODS

CCT was measured by ultrasound pachymetry in PACG eyes and compared with primary open-angle glaucoma (POAG) eyes. POAG eyes were further subdivided into high-tension glaucoma (HTG) and normal-tension glaucoma (NTG) for analysis. PACG eyes had glaucomatous optic neuropathy and visual field loss, an angle in which at least 180 degrees of angle in which the posterior trabecular meshwork was not visible, and raised intraocular pressure (IOP) and/or peripheral anterior synechiae. Both HTG (IOP >21 mm Hg) and NTG (IOP consistently <21 mm Hg) eyes had glaucomatous optic neuropathy with compatible visual field defects and open angles. Further comparison was made with CCT data of 1067 normal subjects previously enrolled in a population-based study.

RESULTS

We enrolled 154 patients with PACG and 300 with POAG. Mean age of PACG patients was 68.1±8.3 years compared with 71.1±12.4 years in POAG patients (P=0.002). There was no difference in mean CCT of PACG eyes (541.28±33.95 μm) and POAG eyes (539.28±34.84 μm, P=0.56) or normal eyes of control subjects (536.74±31.08 μm) (P=0.07). However, mean CCT of NTG eyes (535.23±36.10 μm) was significantly lower than that of HTG eyes (543.44±33.10 μm, P=0.04), and HTG eyes had thicker CCT than normal eyes (P=0.01).

CONCLUSIONS

PACG eyes had similar CCT as those with POAG or normal eyes in Chinese subjects.

Corneal biomechanical properties of patients with pseudoexfoliation syndrome

PURPOSE

To assess the corneal biomechanical properties of patients with pseudoexfoliation syndrome (PEX syndrome).

METHODS

Fifty-two eyes of 52 patients (27 unilateral and 25 bilateral) and 42 eyes of 42 age-matched control subjects were enrolled in the study. Metrics of corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with the ocular response analyzer (ORA). The ORA also determined the values of Goldmann-correlated intraocular pressure and corneal-compensated intraocular pressure. Central corneal thickness (CCT) was measured by the ORA integrated handheld ultrasonic pachymeter. The values recorded by the ORA were compared between eyes with PEX syndrome and those without PEX syndrome. Eyes with unilateral PEX syndrome and fellow eyes without PEX syndrome were also compared.

RESULTS

The mean CH and CRF of all eyes with PEX syndrome were significantly lower than those of control eyes (P < 0.05). Neither corneal-compensated intraocular pressure nor Goldmann-correlated intraocular pressure showed a statistically significant difference in both the groups. Mean CCT values also did not show significant difference. Comparison of the unilateral eyes with PEX syndrome with the apparently normal fellow eyes revealed no significant difference between the mean CCT, mean CH, and mean CRF values (P > 0.05). However, the mean corneal-compensated intraocular pressure and Goldmann-correlated intraocular pressure were relatively higher in the PEX syndrome eye (P < 0.05). There was no significant difference between the mean CCT values of these groups (P > 0.05).

CONCLUSIONS

The CH and CRF decrease in both unilateral and bilateral PEX syndrome suggested that PEX syndrome has a weakening effect on corneal biomechanical properties. Moreover, in subjects with clinically unilateral PEX syndrome, these properties were closer to eyes with PEX syndrome than to normal control eyes.

Differences between Goldmann Applanation Tonometry and Dynamic Contour Tonometry in pseudoexfoliation syndrome

PURPOSE

To evaluate differences between Goldmann Applanation Tonometry (GAT) and Dynamic Controur Tonometry (DCT) in eyes with pseudoexfoliation syndrome (PEX).

METHODS

Thirty-eight patients (38 eyes) with PEX in both eyes (pseudoexfoliative group, PG) as well as 19 patients (19 eyes) without PEX in either eye (control group, CG), were included. All eyes were phakic. GAT, DCT, the central corneal thickness (CCT) and the axial length of the eyeball (AL) were measured and the difference between GAT and DCT (dIOP) was calculated. Differences in dIOP between CG and PG and correlations of dIOP with CCT and AL were examined.

RESULTS

dIOP was significantly (P = 0.02) higher in PG (mean value 3.69 mmHg), compared with CG (mean value 2.15 mmHg). In PG (but not in CG), dIOP was also significantly correlated with AL but not with CCT.

CONCLUSION

The fact that dIOP was significantly higher in PG than in CG implies that PEX may affect ocular biomechanical properties. The significant association of dIOP with AL but not with CCT is in agreement with previous reports and complies with the fact that pseudoexfoliative material is not deposited in corneal stroma.

Correlation between central corneal thickness and intraocular pressure in various age groups

INTRODUCTION

The Pascal Dynamic Contour Tonometer (DCT) is an ophthalmic investigational device which directly calculates the dynamic pulsatile fluctuations in intraocular pressure (IOP) using a piezoelectric pressure sensor embedded in the devices tip.

OBJECTIVE

The aim of this study was to compare IOP results obtained with Goldmann applanation tonometer (GAT), and their correlation with central corneal thickness (CCT) in patients of various age groups.

METHODS

We studied 37 patients (17 male and 20 female), divided into three age groups: younger than 40 years; 40-60 years old, and older than 60 years. In the first and second group there were patients rarely and in the third mostly diagnosed and medicamentously compensated glaucoma. In topical anaesthesia, first we measured CCT, with ultrasound pachimeter, then IOP with DCT and GAT.

RESULTS

Statistically significant difference between measurements of IOP with the DCT and GAT appeared in all groups: I mean diff. -1.71 +/- 1.27 mm; p < 0.0001; II mean diff. -1.19 +/- 1.06 mm; p < 0.0001; III mean diff. -1.69 +/- 1.67 mm; p < 0.0001. CCT was in indirect correlation with the values of IOP measured both with the DCT and GAT in the first and third, while it was in the direct correlation with these values in the second group.

CONCLUSION

CCT had no influence on IOP measurements both with the DCT and GAT in none of the groups. The DCT cannot replace GAT, but it is a reliable device for the measurement of IOP particularly in corneal deformations (keratoconus, after corneal refractive surgery, corneal scars, etc.).

Epidemiology of exfoliation syndrome in the Reykjavik Eye Study

Exfoliation syndrome (XFS) is a major risk factor for glaucoma. It is characterized by a pathological accumulation of polymorphic fibrillar material in the anterior segment of the eye. It is likely that the increase in intraocular pressure (IOP) seen in XFS patients is at least in part because of flakes of material clogging up the trabecular meshwork, and thereby increasing the resistance to outflow and increasing IOP. XFS glaucoma progresses more rapidly, is more resistant to medical treatment and has worse prognosis than other glaucomas. The prevalence of XFS has been found to vary greatly between different studies, raising the possibility of racial and/or environmental modulators. XFS has also been linked to other changes in ophthalmological structures such as; changes in central corneal thickness (CCT), steeper corneal curvature (CC) and nuclear lens opacifications. Some studies have found XFS to be associated with systemic diseases, mostly cardiovascular and cerebrovascular. Exposure to ultra-violet (UV) light has also been investigated as a possible culprit, along with several other plausible factors. The aim of the present study was to determine the prevalence and 5-year incidence of XFS, to establish possible risk factors and/or concomitant symptoms and finally to investigate the relationship between XFS and glaucomatous changes. The Reykjavík Eye Study (RES) is a prospective study based on a random sample from the Icelandic national population sample. The baseline examination was performed in the autumn of 1996, when 1045 persons older than 50 years participated. Of these, 846 (88.2% of survivors) participated in a follow-up 5 years later. All participants went through a standard examination protocol, and answered a comprehensive questionnaire on health and life style. In the prevalence study, XFS was found in 10.7% of subjects, more frequently in women and older persons. Five years later, a further 5.2% of those that participated in the follow-up study and had no signs of XFS at baseline were diagnosed having XFS. We found a strong correlation between IOP and XFS. No difference was found in the anterior segment parameters measured, but there was a significant loss of neural tissue in the XFS as demonstrated by measurements of cup/disk ratio. In conclusion, we find XFS to be frequent among Icelanders, increasing with age and more in women. Our diagnostic criteria are reliable over time. We have also identified possible risk factors that point to a role of antioxidants in the development of XFS. We find changes in corneal curvature and thickness more related to age than XFS.

Central corneal thickness in subjects with glaucoma and in normal individuals (with or without pseudoexfoliation syndrome)

Objective:

The evaluation of central corneal thickness (CCT) in subjects with pesudoexfoliation glaucoma (PEXG), primary open-angle glaucoma (POAG), and in normotensive individuals with or without pseudoexfoliation syndrome (PXS).

Study design/patients and methods:

CCT was evaluated with ultrasound pachymetry in a total of 179 individuals: 32 had bilateral PEXG, 55 had bilateral POAG, 35 had PXS, and 57 were healthy individuals without PXS.

Results:

CCT in PEXG eyes (526.00 ± 34.30 μm) was significantly thinner compared to POAG eyes (549.36 ± 39.3 μm) (P = 0.027) and normal control eyes with (550.64 ± 39.0 μm) or without PXS (547.36 ± 33.1 μm), (P = 0.039 and 0.048 respectively). No statistically significant difference was found comparing CCT values of POAG eyes to control group eyes.

Conclusion:

The evaluation of CCT is necessary in all patients with glaucoma and especially in those with PEXG due to the thinner cornea and the risk of underestimation of intraocular pressure.

Relationship between central corneal thickness and visual field defect in open-angle glaucoma

PURPOSE

To explore the relationship between central corneal thickness (CCT) and visual field defect in open-angle glaucoma (OAG).

METHODS

In this cross-sectional study, we tested 344 eyes in 344 eligible patients, including 233 with normal-tension glaucoma (NTG) and 111 with primary open-angle glaucoma (POAG). The association among variables, especially that between visual field defect and CCT, was probed by multivariate regression in eyes with NTG or POAG, and in all eyes. All eyes were divided into early, moderate, or severe visual field defect groups according to Anderson's classification. Statistical analysis was performed for all cases, and for the three CCT groups.

RESULTS

Multivariate regression analysis revealed an association between CCT and visual field defect in eyes with NTG but not in eyes with POAG or in all eyes. The eyes with early visual field defect had greater CCT than did those with severe visual field defect (533.2 versus 519.0 microm). The eyes with greater CCT had better visual field indices than did those with thinner CCT (-6.91 versus -9.17 dB).

CONCLUSIONS

Central corneal thickness is a factor associated with the status of the visual field defect: a greater CCT is associated with a better visual field index. Other factors such as the glaucoma subtype play a role in the effect of CCT on visual field defect.

Bilateral juvenile open angle glaucoma in two Chinese children: case report

Two cases of bilateral juvenile open angle glaucoma (JOAG) in a four-year-old Chinese boy and a 12-year-old Chinese girl are reported. Applanation tonometry revealed elevated intraocular pressure (IOP) in both eyes. The patients were asymptomatic and bilateral open angle glaucoma was confirmed by a paediatric ophthalmologist. One patient had surgery (trabeculectomy), while the other was treated with topical medication. The early detection and treatment of JOAG is essential for the preservation of vision. Tonometry must be performed as part of a routine eye examination regardless of the age of the patient.

Pseudoexfoliation in the Reykjavik Eye Study: prevalence and related ophthalmological variables

PURPOSE

To examine the age and sex-specific prevalence of pseudoexfoliation syndrome (PEX) and its relationship with some ophthalmological variables.

METHODS

We carried out a population-based study using a random sample taken from the national population census for citizens of Reykjavik, aged > or = 50 years. A total of 1045 individuals participated in all parts of the study. Pseudoexfoliation was established by slit-lamp examination with a maximally dilated pupil carried out by two experienced ophthalmologists, who were masked to one another's results except in cases of disagreement where they had to reach a consensus.

RESULTS

In all, 108 (10.7%) persons were found to have PEX in at least one eye. Prevalence increased from 2.5% in those aged 50-59 years to 40.6% in those aged > or = 80 years. Women were more frequently affected than men (12.3% versus 8.7%). This difference remained statistically significant after controlling for the effect of age (p < 0.001). Eyes with PEX were found to have higher intraocular pressure (IOP) than eyes without PEX (p < 0.05). However, PEX was not found to be related to central corneal thickness, anterior chamber depth, lens thickness, nuclear lens opacifications or optic disc morphology in a multivariate model.

CONCLUSIONS

Pseudoexfoliation is an age-related phenomenon commonly found in Iceland. It is more commonly found in women than in men and is associated with elevated IOP.

Corneal curvature and central corneal thickness in eyes with pseudoexfoliation syndrome

BACKGROUND

Previous studies have reported different central corneal thickness (CCT) values in eyes with pseudoexfoliation syndrome (PXS). There has been no report about corneal curvature (CC) in PXS eyes. The aim of this study was to investigate the CCT together with the CC in PXS eyes with and without glaucoma.

METHODS

The CC (simulated keratometry 1 [SimK1], SimK2, and mean K) and CCT were prospectively studied by rotating a Scheimpflug camera in 72 PXS eyes and comparing them with 65 normal eyes.

RESULTS

In all PXS eyes, the mean K was significantly steeper than in control eyes (44.1 [SD 1.5] diopters (D) vs. 43.2 [SD 2.0] D, p = 0.04). When PXS eyes were subcategorized, the mean K was significantly steeper in both normotensive PXS eyes (44.6 [SD 1.6] D) and pseudoexfoliation glaucoma (PEXG) eyes (44.0 [SD 1.2] D) than normal eyes (43.2 [SD 2.0] D) (p = 0.001 and 0.02, respectively). In all PXS eyes, the mean CCT (546.4 [SD 39.6] microm) was not significantly different than the control eyes (542.9 [SD 32.2] microm) (p = 0.56). When PXS eyes were subcategorized, however, the CCT was significantly thinner in normotensive PXS eyes and significantly thicker in PEXG eyes.

INTERPRETATION

It appears that PEXG eyes have a significantly steeper CC and higher CCT than normal eyes. This could be of clinical significance because overestimation of true intraocular pressure may then occur in these eyes.