A Study of Central Corneal Thickness in Glaucoma and Nonglaucoma Patients in a West African Population

Central Corneal Thickness and Its Association with the Severity of Primary Open-Angle Glaucoma

Background

Understanding the relationship between central cornea thickness and glaucoma severity will help in assessing individualised risk and will enhance evidence-based decision-making in the early diagnosis and management of glaucoma.

Aim

We aimed to determine the correlation between central corneal thickness (CCT) and the severity of glaucoma at different stages of primary open-angle glaucoma (POAG) at the Federal Medical Centre (FMC), Lokoja, Nigeria.

Materials and Methods

A cross-sectional study of POAG patients at presentation to FMC, Lokoja. Biodata, use of anti-glaucoma medications, and family history of glaucoma were obtained. Examinations included visual acuity, central visual fields, slit lamp examination, pachymetry, gonioscopy, indirect fundoscopy, and fundus photograph. The correlation between CCT and the above parameters was ascertained. Using the mean deviation, the severity of glaucoma was classified: as mild glaucoma <-6 dB, moderate glaucoma -6 to -12 dB, severe glaucoma -12 to -18 dB, and end-stage glaucoma >-18 dB.

Results

A total of 242 eyes of 121 POAG patients were studied. The male-to-female ratio was 1.5:1. The mean age was 55 ± 10 years (range = 40-78 years). Most (65.7%) had not used anti-glaucoma medications and 17.4% gave a positive family history of glaucoma. There was no clinical correlation between positive family history and CCT (P = 0.71) and no correlation between family history and glaucoma severity (P = 0.96). The patients were classified as mild glaucoma 63(29.9%), moderate glaucoma 95(45%), severe glaucoma 30 (14.2%), and end-stage glaucoma 23 (10.9%). The mean CCT was 508.0 ± 32μm. There was a decrease in CCT from 517.94 ± 26μm in mild glaucoma to 504.96 ± 40μm in end-stage glaucoma; this difference was statistically significant (P = 0.031). The mean intraocular pressure (IOP) was 24 ± 7 mm Hg, whereas the mean corrected IOP was 27 ± 8 mm Hg.

Conclusion

There was a negative significant correlation between CCT and glaucoma severity and between CCT and true IOP. CCT did not correlate with age, sex, family history, or laterality of POAG.

Normative corneal biometric parameters in sub-Saharan African populations: A systematic review and meta-analysis

BACKGROUND

Despite the importance of corneal biometric parameters in ophthalmology, there is limited comprehensive data on these measurements in Sub-Saharan African (SSA) populations. This study systematically reviewed the evidence on corneal biometric parameters of Sub-Saharan African populations, focusing on their variability, influencing factors, and implications for clinical practice and public health interventions.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines. Eligible studies published between January 2003 and December 2023 were identified through comprehensive searches in PubMed, Scopus, and Web of Science, with a specific focus on African populations. Inclusion criteria comprised non-interventional studies reporting central corneal thickness (CCT), corneal curvature, radius of curvature, or horizontal corneal diameter (HCD) of eyes of continental Africans. Data were synthesized using random-effects meta-analyses, with heterogeneity assessed using the I2 statistic. Subgroup analyses examined variations by geographic region, measurement instrument, and sex.

RESULTS

Twenty-eight studies with a total of 14,009 participants were included. The pooled mean CCT was 553.35 µm (95 % CI: 548.52-558.18 µm), with regional variations ranging from 555.66 µm in West Africa to 510.17 µm in Southern Africa. Males exhibited slightly higher CCT values compared to females (539.11 µm vs. 533.78 µm). Additional parameters assessed included mean corneal curvature (43.07 D), radius of curvature (7.70 mm), and HCD (11.59 mm). Variability in the measurements was attributed to demographic, geographic, and methodological factors.

CONCLUSIONS

Corneal biometric parameters exhibit substantial regional and demographic variability in SSA. These findings underscore the importance of population-specific data in enhancing diagnostic precision and guiding the development of regionally tailored clinical protocols. Further research is needed to address current knowledge gaps and improve eye care outcomes across the African continent.

FUNDING

This research received no specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Profile of central corneal thickness and corneal endothelial cell morpho-density of in healthy Congolese eyes

Purpose

To determine the pachymetric and corneal endothelial cell morphometric features and their relationship to ocular and systemic factors in healthy Congolese subjects.

Methods

Non-contact specular microscopy was used in 278 healthy eyes (278 subjects) to measure central corneal thickness (CCT), corneal endothelial cell density (CECD) along with cell size, coefficient of variation (CV) in cell size, and hexagonality (HEX). The lower and upper reference limits and average values for each parameter were determined. Correlation and association of average values with anthropo-demographic and clinical variables were assessed.

Results

The mean age was 38.9 ± 17.2 years (10.9–80.7 years). Average values were 504.2 ± 30.7 μm (CCT), 2907.1 ± 290.9 cells/mm² (CECD), 348.5 ± 38.4 μm² (cell size), 32.9 ± 3.6% (CV), and 51.8 ± 7.2% (HEX). CCT was 504.9 ± 33.6 μm in men and 503.6 ± 28.3 μm in women (p = .73); values for CECD were 2917.1 ± 253.5 cells/mm² and 2899.2 ± 317.8 cells/mm² (p = 0.61), respectively. Lower and upper reference limits were 449.6 μm and 566.0 μm for CCT, and 2165.3 cells/mm² and 3414.4 cells/mm² for CECD, respectively. CCT correlated with body mass index (BMI), (r = − 0.12, P = 0.04). CECD decreased with age (r = − 0.49, P < 0.001), BMI (r = − 0.20, P = 0.001), intraocular pressure (r = − 0.13, P = 0.029) and ocular perfusion pressure (r = − 0.28, P = 0.028). CECD decayed by 8.3 cells/mm² or 0.30% per year of age and CCT decreased by 0.72 μm per kg/m².

Conclusions

Mean central cornea was thinner, CECD higher, and references limits lower than reported in other African populations. The CCT and CECD normative values reported herein will be useful for both clinical and research purposes in this population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01947-x.

Correlation between central corneal thickness and visual field defects, cup to disc ratio and retinal nerve fiber layer thickness in primary open angle glaucoma patients

Objective:

To evaluate the correlation between Central Corneal Thickness (CCT) and Visual Field (VF) defect parameters like Mean Deviation (MD) and Pattern Standard Deviation (PSD), Cup-to-Disc Ratio (CDR) and Retinal Nerve Fibre Layer Thickness (RNFL-T) in Primary Open-Angle Glaucoma (POAG) patients.

Methods:

This cross sectional study was conducted at Armed Forces Institute of Ophthalmology (AFIO), Rawalpindi from September 2015 to September 2016. Sixty eyes of 30 patients with diagnosed POAG were analysed. Correlation of CCT with other variables was studied.

Results:

Mean age of study population was 43.13±7.54 years. Out of 30 patients, 19 (63.33%) were males and 11 (36.67%) were females. Mean CCT, MD, PSD, CDR and RNFL-T of study population was 528.57±25.47µm, -9.11±3.07, 6.93±2.73, 0.63±0.13 and 77.79±10.44µm respectively. There was significant correlation of CCT with MD, PSD and CDR (r=-0.52, p<0.001; r=-0.59, p<0.001;r=-0.41, p=0.001 respectively). The correlation of CCT with RNFL-T was not statistically significant (r=-0.14, p=0.284).

Conclusion:

Central corneal thickness had significant correlation with visual field parameters like mean deviation and pattern standard deviation, as well as with cup-to-disc ratio. However, central corneal thickness had no significant relationship with retinal nerve fibre layer thickness.

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.

Effect of supine body position on central corneal thickness

BACKGROUND

To evaluate the effect of supine body position on central corneal thickness (CCT) in open-angle glaucoma patients and in healthy subjects.

DESIGN

A cross-sectional study at a university eye clinic.

PARTICIPANTS

Twenty-three subjects were recruited in each group, for a total of 46 patients.

METHODS

CCT was measured using an ultrasound pachymeter in each subject. Three consecutive measurements in each eye were first taken in the sitting position, and repeated after 10 min and 30 min in a supine position. Results were analyzed using mixed model repeated measures, which adjusted for age, gender and laterality of eyes.

MAIN OUTCOME MEASURES

CCT RESULTS: In healthy subjects, CCT decreased with supine positioning at 10 min (mean = -5.2 µm, P = 0.0043) and at 30 min (mean = -6.5 µm, P < 0.0001). In the glaucoma group, CCT decreased with supine positioning at 10 min (mean = -6.7 µm, P = 0.0043) and at 30 min (mean = -10.2 µm, P < 0.0001). There was no statistically significant difference between the CCT at 10 min supine and at 30 min supine in the healthy subjects (P = 0.37) and glaucoma patients (P = 0.14). CCT was shown to decrease linearly over time (P < 0.0001), and the slopes were not statistically different between groups (P = 0.40).

CONCLUSIONS

CCT is a dynamic measurement that can be influenced by body position. It decreases linearly in the first 30 min of supine positioning at a similar rate in both open angle glaucoma patients and in healthy subjects.

A review of African studies on central corneal thickness

Recently, there has been increasing interest in understanding central corneal thickness (CCT) measurements in various populations. This may be related to the influence of CCT in the diagnosis, classification and management of glaucoma. In addition, CCT measurements are also important for monitoring corneal diseases and contact lens wear, indicating the overall health of the cornea and assessing eligibility for refractive surgery. This article reviews studies that have reported CCT measurements in non-glaucomatous African sub-populations. The CCT measurements, gender associations and limitations of these studies are highlighted. The findings of these studies and their implications are discussed in relation to global studies reporting on CCT measurements.

Intra-Ocular Pressure Measurement in a Patient with a Thin, Thick or Abnormal Cornea

Accurate measurement of intra-ocular pressure is a fundamental component of the ocular examination. The most common method of measuring IOP is by Goldmann applanation tonometry, the accuracy of which is influenced by the thickness and biomechanical properties of the cornea. Algorithms devised to correct for corneal thickness to estimate IOP oversimplify the effects of corneal biomechanics. The viscous and elastic properties of the cornea influence IOP measurements in unpredictable ways, a finding borne out in studies of patients with inherently abnormal and surgically altered corneal biomechanics. Dynamic contour tonometry, rebound tonometry and the ocular response analyzer provide useful alternatives to GAT in patients with abnormal corneas, such as those who have undergone laser vision correction or keratoplasty. This article reviews the various methods of intra-ocular pressure measurement available to the clinician and the ways in which their utility is influenced by variations in corneal thickness and biomechanics.

The effect of medical therapy on IOP control in Ghana

BACKGROUND

To investigate IOP control following twelve months of continuous medical therapy in Ghana.

METHODS

This retrospective case series included 163 glaucoma patients diagnosed at a referral eye center between 1996 and 2006. Information collected included age, gender, IOP at presentation, six months and one year post treatment and types of anti-glaucoma medications prescribed. Optimal IOP control was defined according to results from the Advanced Glaucoma Intervention Study (AGIS), which demonstrated arrest of visual field progression in patients with IOP < 18 mmHg at all visitations: Level 1 (post-treatment IOP ≤ 21 mmHg); Level 2 (≤ 18 mmHg) and level 3 (≤ 16 mmHg). The principal outcome measure was the achievement of IOP <18 mmHg at six months and twelve month visitations.

RESULTS

One hundred sixty three patients were analyzed. These included 68 males (41.7%) and 95 females (58.3%). The mean age was 57±16 (median 59 years; range 7 - 95 years). There was no significant difference in age (p=0.35) or mean IOP (p=0.08) between genders. The mean pre-treated IOP of 31.9±8.9 mmHg significantly decreased to 21.3±6.6 mmHg at 6 months (p=0.001), with 57.4% of eyes at Level 1 IOP control, 25.3% at Level 2 and 15.4% at Level 3 and decreased further at 12 months to 20.7±6.9 mmHg (p=0.48) with 69.7% of eyes at Level 1, 34.4% at Level 2, and 12.4% at Level 3.

CONCLUSIONS

Current medical regimen is insufficient to reduce IOP to target levels as defined in the Advanced Glaucoma Intervention Study.

Central corneal thickness measurements in premature infants

AIM

To evaluate the central corneal thickness (CCT) measurements of premature infants.

METHODS

The premature infants who were born between 25-34wk of gestational age (GA) were retrieved for the study. All CCT measurements were performed within the first 2d of their life under topical anesthesia by using an ultrasonic pachymeter.

RESULTS

The mean CCT of 200 eyes was 647.79±63.94 µm. The mean CCT of the right and left eyes were similar (647.30±64.72 µm and 648.29±63.47 µm consecutively). The mean CCT of the girls was 642.08±54.89 µm and the boys was 653.07±71.14 µm, with no statistically significant difference (P>0.05). But there was a negative correlation of the CCT with GA and birth weight (BW) (P<0.01).

CONCLUSION

The CCT values of premature babies were negatively correlated with GA and BW.