Comparing Central Corneal Thickness in a Sub-Saharan Cohort to African Americans and Afro-Caribbeans

Understanding racial disparities of glaucoma

PURPOSE OF REVIEW

Increased prevalence, earlier onset, and more rapid progression to vision loss from glaucoma has demonstrated racial disparity in numerous studies over decades. Precise etiologies of these important differences among patients of African and Hispanic ancestral background have not been elucidated. This review focuses on currently available epidemiologic/population, genetic, socioeconomic and physiologic studies of racial disparities in this blinding disease.

RECENT FINDINGS

In depth reviews of several landmark studies of glaucoma prevalence in various racial groups have highlighted potential challenges of lack of recruitment of diverse populations in genetic studies and clinical trials, challenges of racial stratification of subjects, and the impact of socioeconomic variables.

SUMMARY

Through a more comprehensive analysis of racial disparities of glaucoma, both clinicians and researchers may provide more effective population screening and management with a holistic approach for individualized patient care to provide improved outcomes. Future studies of interventions in sociodemographic factors and genetic/physiologic variables that influence the prevalence, access, and consequential vision loss from glaucoma will be crucial to minimize/eliminate racial disparities and improve outcomes for all.

Ocular parameters and anthropometry in Indo-Trinidadians

To assess ocular parameters and their association with anthropometric measurements in Indo-Trinidadians adults. This was a clinical, descriptive, cross-sectional study of ocular parameters and anthropometry in adults Trinidadians of South Asian descent (Indo-Trinidadian). Ocular parameters were measured using optical coherence tomography, intraocular lens master biometer, and an autorefractor. Weight, height, and body mass index (BMI) were measured by anthropometry. Univariable and multivariable linear regressions were used to determine the association between demographic variables, anthropometric and ocular parameters. A total of 149 participants (298 eyes) comprising of 90 females (60.6%) and 59 males (39.4%). Aged 18 to 67 participated in the study. Males were taller, heavier, and had longer axial lengths than females which were statistically significant (P < .05). Age was negatively correlated with central corneal thickness (CCT) (r = -0.353, P = .044) and retinal nerve fiber layer thickness (r = -0.348, P = .047) but positively correlated with lens thickness (R = 0.881, P < .001). Education level was positively associated with CCT (R = 0.408, P = .018) but negatively associated with lens thickness (r = -0.521, P = .002). Weight was negatively correlated with corneal topography (r = -0.427, P = .013). Height was negatively correlated with cup-to-disc ratio (r = -0.410, P = .018), CCT (r = -0.382, P = .028), and corneal topography (r = -0.453, P = .008). There was no correlation between BMI, ocular parameters and CCT. There was a significant difference in the ocular parameters between males and females of South Asian descent in Trinidad and Tobago. Weight was negatively associated with the corneal topography. Height was negatively associated with the cup-to-disc ratio, central corneal thickness, and corneal topography. BMI had no statistically significant association with the ocular parameters investigated.

Clinical Profile of Primary Open-angle Glaucoma Patients at an Eye Center in Nigeria

Aim

Globally, one of the leading causes of preventable blindness is primary open-angle glaucoma (POAG). The study assessed the clinical presentations of POAG patients attending an eye center in Abuja, Nigeria.

Materials and methods

Records of 188 eyes, collected from 94 patients diagnosed with POAG for a period of 1 year at the eye center, were reviewed. Clinical records, including age, gender, visual acuity (VA), central cornea thickness (CCT), intraocular pressure (IOP), cup-to-disk ratios, and retinal nerve fiber layer (RNFL) thickness of the participants, were extracted and analyzed.

Results

The majority of the participants were males (56.4%) and adults (57.4%), most of whom had normal VA (>70% in each eye). Our analysis revealed normal average estimates of RNFL thickness, IOP, and CCT among the participants. Females had thicker RNFL compared to males (p = 0.02). Although CCT decreased with age (r = -0.28, p = 0.005), there was no such link between IOP and CCT (r = 0.09, p = 0.38).

Conclusion

Central cornea thickness (CCT), RNFL thickness, and IOP in isolation should not be used as early indicators for POAG; rather, a combination of these and other indices is recommended. Early detection through active screening and treatment in the community for at-risk groups is highly advised.

How to cite this article

Ezinne NE, Kwarteng MA, Ekemiri KK, et al. Clinical Profile of Primary Open-angle Glaucoma Patients at an Eye Center in Nigeria. J Curr Glaucoma Pract 2023;17(3):113-117.

Glaucoma Cascade Screening in a High Risk Afro-Caribbean Haitian Population: A Pilot Study

PRCIS

Glaucoma cascade screening in first-degree relatives (FDRs) of young Haitian glaucoma patients had high yield for diagnosing manifest and suspected glaucoma in 30.8% of those screened despite modest participation.

PURPOSE

To evaluate the outcomes of glaucoma cascade screening in FDRs (parents, siblings, and offspring) of Haitian juvenile open-angle glaucoma (JOAG) patients.

PATIENTS AND METHODS

Consecutive index patients (Haitians with JOAG) were identified, and the number/type of FDRs residing in South Florida were recorded. These FDRs were invited for free glaucoma screening, which included a comprehensive ophthalmic exam, gonioscopy, automated visual field testing and optical coherence tomographic analysis of the retinal nerve fiber layers. FDR characteristics and clinical findings from screening are reported.

RESULTS

A total of 77 FDRs were invited, 26 (33.8%) agreed to undergo screening (18 females, 9 males), which revealed 2 (7.7%) with manifest glaucoma (mean age 77.5 y; one of whom was previously unaware of his glaucoma diagnosis), 6 (23.1%) with suspected glaucoma (mean age 29.8±18.3 y), and 18 (69.2%) without manifest or suspected glaucoma (mean age 37.2±21.8 y). Siblings of index patients were least likely to participate in cascade glaucoma screening when compared with index patients' parents or offspring. FDR eyes with manifest glaucoma had significantly worse best-corrected visual acuities, higher intraocular pressures, thinner central corneal thicknesses, and thinner circumferential papillary retinal nerve fiber layer thicknesses than those without glaucoma.

CONCLUSION

Glaucoma cascade screening of Haitian JOAG patients' FDRs revealed that 30.8% had suspected or manifest glaucoma. Future efforts centered on provider-initiated recruitment and improving public glaucoma awareness and education may increase screening participation.

Ethnic Differences of Corneal Parameters: A Cross-Sectional Study

Purpose:

To investigate the ethnic differences of corneal parameters in Arabs and other ethnicities.

Methods:

This study recruited 250 Saudi Arabian participants, 18–45 years of age. The McMonnies questionnaire was used to exclude participants with dry eye. The KR8800 auto refractometer (Topcon, Japan) was used to measure the refractive error. Oculus Keratograph 4 topography was used to assess 16 corneal parameters, including the k-readings, horizontal visible iris diameter, mean eccentricity index, asphericity, corneal shape factor, corneal flattening factor, sagittal height, sagittal curvature, and vertical palpebral aperture.

Results:

A statistically significant difference was found between male and female participants. Corneal parameters were compared to other ethnicities, including Caucasians and Asians, and those of Mongoloid origin. The horizontal visible iris diameter was wider in Saudi Arabians than in Asians but similar to Caucasians. The sagittal height was deeper and the corneal shape factor was higher than in the other ethnicities, and the eccentricity index was lower than that in Caucasians and Asians of Mongoloid origin.

Conclusion:

Our data provided normative corneal parameters of Saudi Arabians that may be useful for ophthalmic clinicians and designers of contact lenses. Furthermore, the parameters suggest that the corneal characteristics of Arabians are distinct from those of major ethnicities.

[Evaluation of mean macular thickness by optical coherence tomography (SD OCT) in black Senegalese subjects]

INTRODUCTION

Our goal was to evaluate the normal macular thickness in Blacks by OCT and to determine socio-demographic and clinical parameters which may influence it.

MATERIALS AND METHODS

This was a multicenter, prospective, descriptive study over 6 months. It included Black adults followed in the ophthalmology departments of Abass Ndao and Aristide-Le-Dantec hospitals in Dakar. Included subjects had corrected visual acuity of 10/10 (0 logMAR) and P2 (+0.1 logMAR), clear ocular media, and no retinal abnormalities. We used the Topcon 3D 2000 OCT to measure the central thicknesses of the cornea (CT) and of the macula (MT), and cup to disc ratio (C/D) in each eye. Socio-demographic, clinical and tomographic data were collected on a survey form and correlated to the MT. The analysis was carried out by the Epi info 7 software. We used the Chi² comparison test with a P value˂0.05.

RESULTS

One hundred and nine patients were included. The mean age was 27.39 years with a male/female ratio of 0.65. The subjects were emmetropic in 54.13% of cases. The mean CT was 519.97μm, the mean C/D was 0.23, and the mean MT was 264.35μm. The P-value (P) was greater than or equal to 0.1 for all the factors studied.

CONCLUSION

MT in our study was lower than that of Whites, and the various parameters studied did not demonstrate a statistically significant influence on MT.

A Pilot Study to Evaluate the Oral Microbiome and Dental Health in Primary Open-Angle Glaucoma

PURPOSE

To evaluate possible associations between primary open-angle glaucoma (POAG), dental health, and the oral microbiome.

METHODS

Case-control study was conducted at SUNY Downstate. Adult subjects (40 to 87 y) were recruited as POAG cases (n=119) and controls without glaucoma (n=78) based on visual field and optic nerve criteria. Overall 74.6% were African Americans (AA). Information on medical history and oral health was collected and ophthalmologic examinations were performed. Mouthwash specimens (28 AA cases and 17 controls) were analyzed for bacterial DNA amounts. Analyses were limited to AAs as the predominant racial group. Outcome measures included number of natural teeth, self-reported periodontal health parameters, and amounts and prevalence of oral bacterial species. Logistic regression was used to evaluate associated factors and potential interactions.

RESULTS

Cases and controls had similar age (mean: 62.2 and 60.9 y, respectively, P>0.48), and frequency of hypertension, diabetes, but cases had a higher proportion of men (P<0.04). On average (±SD), cases had fewer natural teeth than controls [18.0 (±11.1) vs. 20.7 (±9.4)]. Having more natural teeth was inversely associated with POAG, in multivariable analyses, at older ages [eg, odds ratio (95% confidence interval) at age 55: 1.0 (0.95-1.06), P=0.98 vs. at age 85: 0.87 (0.79-0.96), P=0.007]. Amounts of Streptococci were higher in cases than controls (P<0.03) in samples from the subset of subjects analyzed.

CONCLUSIONS

The number of teeth (an oral health indicator) and alterations in the amounts of oral bacteria may be associated with glaucoma pathology. Further investigation of the association between dental health and glaucoma is warranted.

Effect of age, sex, and refractive errors on central corneal thickness measured by Oculus Pentacam®

BACKGROUND

Central corneal thickness (CCT) can be used to assess the corneal physiological condition as well as the pathological changes associated with ocular diseases. It has an influence on the measurement of intraocular pressure and is being used as a screening tool for refractive surgery candidates. The aim of this study was to determine the median CCT among normal Pakistani population and to correlate CCT with age, sex, and refractive errors.

METHODS

We conducted a retrospective analysis of 5,171 healthy eyes in 2,598 patients who came to Hashmanis Hospital, Karachi, Pakistan. The age of the patients ranged from 6 to 70 years. The refractive error was gauged by an auto-refractometer, and CCT was measured using Oculus Pentacam^®.

RESULTS

The median CCT of our study was 541.0 μm with an interquartile range (IQR) of 44.0 μm. The median age was 26.0 years (IQR: 8.0). Median spherical equivalent (SE) of the patients was -4.3 D (IQR: 3.3) with the median sphere value as -4.0 D (IQR: 3.8). Lastly, the median cylinder was -1.0 D (IQR: 1.3). Age has a weak negative correlation with CCT (r=-0.058) and shows statistical significance (P<0.001). Additionally, males had thinner CCT readings than females (P=0.001). The cylinder values, on the other hand, had a significant (P=0.004) and positive correlation (r=0.154). Three values showed no significant correlation: sphere (P=0.100), SE (P=0.782), and the left or right eye (P=0.151).

CONCLUSION

Among the Pakistani population, CCT was significantly affected by three variables: sex, age, and cylinder. No relationship of CCT was observed with the left or right eye, sphere, and SE.

Central Corneal Thickness and its Associations With Ocular and Systemic Factors in an Urban West African Population

PURPOSE

To assess the associations of central corneal thickness (CCT) with ocular and systemic factors in a West African population.

DESIGN

Population-based cross-sectional study.

METHODS

Participants aged ≥40 years in the Tema Eye Survey who had clinically normal corneas were included in this study. CCT was determined bilaterally using handheld ultrasound pachymetry. The association between CCT and ocular or systemic factors was analyzed with univariable linear regression. Multivariable linear regression analysis was performed for variables significantly associated with CCT in the univariable analysis. Main outcome measures were CCT (μm) and its associations with age, sex, IOP, cup-to-disc ratio (CDR), glaucoma, hypertension, and diabetes.

RESULTS

A total of 6806 eligible subjects were identified, of whom 5603 (82.3%) participated in the Tema Eye Survey. A total of 4737 participants (84.5% of participants) of West African descent and clinically normal corneas were included. The mean age ± standard deviation (SD) of participants was 51.2 ± 9.7 years and 38.7% were male. The mean ± SD CCT in the population was 533.9 ± 34.0 μm. In the multivariable linear regression analysis, increased CCT was significantly associated with younger age, male sex, and higher IOP (all P < .001). There were no significant associations between CCT and CDR, glaucoma, hypertension, and diabetes.

CONCLUSIONS

This population-based cross-sectional survey of West African adults found a significant association between increased CCT and younger age, male sex, and higher IOP but not glaucoma or CDR. Variations in corneal thickness may influence the accuracy of IOP measurements in African persons.

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.

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.

Central corneal thickness correlates with oxygen levels in the human anterior chamber angle

PURPOSE

To measure oxygen (pO2) in eyes of patients undergoing intraocular surgery and identify correlations with central corneal thickness (CCT).

DESIGN

Prospective, cross-sectional study.

METHODS

setting: Institutional. patient population: 124 patients undergoing cataract and/or glaucoma surgery. observation procedure: Prior to surgery, an oxygen sensor was introduced into the anterior chamber (AC) via peripheral corneal paracentesis. The tip of the flexible fiberoptic probe was positioned for 3 measurements in all patients: (1) near central corneal endothelium; (2) in mid-AC; and (3) in AC angle. In patients undergoing cataract extraction, additional measurements were taken (4) at the anterior lens surface and (5) in the posterior chamber. main outcome measures: pO2 measurements at 5 locations within the eye were compared to central corneal thickness measurements by multivariate regression analyses.

RESULTS

There was a statistically significant inverse correlation between CCT and pO2 in the anterior chamber angle (P = .048). pO2 was not significantly related to CCT at any other location, including beneath the central cornea. Regression analysis relating CCT to age, race, and oxygen levels in all 5 locations in the anterior segment revealed an association of a thinner cornea with increasing age (P = .007).

CONCLUSIONS

Physiologic correlations with central corneal thickness may provide clues to understanding why a thinner cornea increases the risk of open glaucoma. Associations between glaucoma risk, CCT, and pO2 in the AC angle suggest that exposure of the outflow system to increased oxygen or oxygen metabolites may increase oxidative damage to the trabecular meshwork cells, resulting in elevation of intraocular pressure.

Age-related changes in central corneal thickness in normal eyes among the adult Lithuanian population

Background

The purpose of this study was to estimate mean central corneal thickness (CCT) and determine whether there are any correlations between CCT, age, and sex in the adult Lithuanian population.

Methods

A total of 1,650 Caucasians of Lithuanian origin (aged 18–89 years) comprising 688 (41.7%) men and 962 (58.3%) women were examined. Subjects were stratified by age into seven groups. CCT was measured using ultrasonic pachymetry. Correlations between CCT, age, and sex were sought.

Results

Mean (± standard deviation) CCT for both eyes was 544.6±30.5 μm. Mean CCT was 545.2±30.5 μm in the left eye and 544.6±30.5 μm in the right eye, and was 545.0±25.6 μm in men and 544.4±33.5 μm in women. Mean CCT was 550.8±35.7 μm in subjects aged 18–29 years, 557.5±27.6 μm in those aged 30–39 years, 551.3±31.4 μm in those aged 50–59 years, 544.0±31.4 μm in those aged 50–59 years, 544.2±31.6 μm in those aged 60–79 years, 535.1±27.8 μm in those aged 70–79 years, and 530.1±16.8 μm in those aged 80–89 years. No statistically significant difference in CCT was found between the sexes (P>0.05). However, there was a significant difference in subjects aged 18–29 years; men had higher CCT than women (P<0.05). A statistically significant negative correlation was found between CCT and age (r=-0.263, P<0.05) that was stronger in men (r=-0.406, P<0.05) than in women (r=-0.118, P<0.05).

Conclusion

The mean CCT in adult Lithuanians was 544.6±30.5 μm, of the left eye 545.2±30.5 μm and of the right – 544.6±30.5 μm. CCT of the right eye was equal to the CCT of both eyes. Mean CCT was 545.0±25.6 μm in men and 544.4±33.5 μm in women. Young men tended to have higher CCT than women. CCT decreases over the lifetime, meaning that older people have thinner corneas. CCT’s dependence on age is stronger in men.

Central corneal thickness in southern Egypt

The study aimed to determine mean central corneal thickness (CCT) in a southern Egyptian population according to gender and age using ultrasonic pachymetry and to compare these CCT measurements to different populations. A prospective, observational, consecutive case series of 4,368 non-glaucomatous subjects (emmetropes and myopes) aged 16-70 years was carried out from August 2010 to March 2013 at the outpatient ophthalmology clinic in Sohag University Hospital and the Laser Vision Center in Sohag City, Egypt. Refraction, keratometry, slit-lamp examination, and intraocular pressure (IOP) measurements were obtained for all subjects. CCT was measured by ultrasonic pachymetry. The average CCT was 530.06 ± 38.03 μm. Average CCT was 532.6 ± 33.3 μm in emmetropes, 531.5 ± 31.3 μm in myopes <6 diopters (D), 531.1 ± 31.4 μm in myopes >6 D and 533 ± 33 μm in hyperopes, with no statistically significant difference between the groups. There was a statistically significant difference in CCT between age groups and gender. There was a strong correlation between CCT and IOP among the non-glaucomatous population. CCT was found to be lower in Egyptians than in Caucasian, Hispanic, and Japanese populations but comparable to African and African American populations.

Central corneal thickness and axial length in an adult Nigerian population

Purpose

The aim of this study was to determine the relationship between central corneal thickness (CCT) and axial length (AL) in adult Nigerians.

Methods

A total of ninety-five (n  = 95) subjects aged between 20 and 69 years consisting of 56 males and 39 females were recruited for this study. The CCT was measured by ultrasound pachymetry using SW-1000P ultrasound pachymeter (Tianjin Suowei Electronics Technologies LTD, China) and the axial length by A-Scan ultrasonography using I-2100 A Scan Biometer (Cima Technology Inc., USA).

Results

The average CCT and AL were 547.0 ± 29.5 μm and 23.5 ± 0.70 mm, respectively. Age inversely correlated with CCT (r  = −0.32, p  = 0.02), but had no effect on AL (r  = 0.082, p  = 0.43). The association between CCT and AL showed an inverse trend but was not statistically significant (r  = −0.10, p  = 0.32). Neither CCT nor AL was affected by gender (p  = 0.11; p  = 0.63, respectively).

Conclusion

CCT decreases with age, but AL was not affected by age. The association between CCT and AL was not significant. Gender did not show any statistically significant effect on CCT and AL.

Age, gender, corneal diameter, corneal curvature and central corneal thickness in Nigerians with normal intra ocular pressure

Purpose

To investigate the relationship between age, gender, corneal diameter, central corneal curvature, central corneal thickness (CCT) and intraocular pressure in Nigerians with normal intraocular pressure.

Methods

One hundred and thirty eyes from 130 subjects (mean age = 47.8 ± 16.8 years) including 77 males and 53 females were recruited. CCT was measured by ultrasound pachymetry, intraocular pressure was determined by non-contact tonometry, horizontal and vertical corneal diameters were measured with a ruler and central corneal curvature was measured by keratometry.

Results

The mean values obtained were as follows: CCT = 548.97 ± 34.28 μm, IOP = 15.61 ± 2.69 mmHg, average corneal curvature (AVK) = 42.98 ± 1.19 D, horizontal corneal diameter (HVID) = 11.39 ± 0.69 mm and vertical corneal diameter (VVID) = 10.51 ± 0.50 mm. There was a significant effect of age on CCT (r = −0.35, p < 0.001). A 10-year-increase in age was associated with a 7.0 μm decrease in CCT. Males had significantly wider HVID than females (p = 0.03). Subjects in older age groups have narrower HVID and VVID. Corneal curvature, corneal diameter and gender did not significantly affect CCT.

Conclusion

CCT of normotensive Nigerian adults decreases with increasing age. There was no correlation between CCT and IOP in normotensive subjects. CCT was not significantly influenced by gender, corneal curvature and corneal diameter.

Central corneal thickness in black Cameroonian ocular hypertensive and glaucomatous subjects

PURPOSE

To evaluate central corneal thickness (CCT) in a black Cameroonian population of ocular hypertensive and glaucomatous subjects.

MATERIAL AND METHODS

This was a prospective study undertaken with an ultrasonic pachymeter from January 2009 to December 2009 in an eye clinic (INNEL Medical center) in Yaoundé, Cameroon.

RESULTS

One hundred subjects (200 eyes) were enrolled in the study. Sixty subjects were glaucomatous (primary open angle glaucoma, POAG group), and 40 ocular hypertensive (OHT group). The mean age of the sample was 52.60 ± 12.23 years. For the whole sample, CCT was 534.71 ± 37.95 μm in the right eye and 533.61 ± 37.67 μm in the left eye, with no statistically significant difference between the 2 eyes (P = 0.446). CCT in the POAG group was 526.30 ± 37.34 μm in the right eye and 524.90 ± 35.92 μm in the left eye. CCT in the OHT group was 547.32 ± 35.71 μm in the right eye and 546.67 ± 36.85 μm in the left eye. There was a statistically significant difference between CCT of the 2 groups (right eye: P = 0.013; left eye: P = 0.007).

CONCLUSION

Mean CCT of ocular hypertensive subjects was thicker than CCT of glaucomatous ones in our Cameroonian sample. However, in both ocular hypertensive or glaucomatous patients, CCT of black Cameroonians is thinner than that reported in other studies in Caucasian populations.

Reasons for not performing LASIK in refractive surgery candidates in Yemen

PURPOSE

To determine and analyze the reasons that laser in situ keratomileusis (LASIK) was not performed in patients who requested refractive surgical correction of their refractive errors.

METHODS

A retrospective observational study was performed in Yemen Magrabi Hospital between June 2005 and October 2006; the case records of 1596 new consecutive patients who presented for refractive surgery at our refractive surgery unit were reviewed. Data on the ocular status, refractive problems, and investigations performed were analyzed. The reasons for not performing LASIK in the cases that were rejected were recorded and analyzed.

RESULTS

A total of 1191 patients (74.6%) were advised to have LASIK of the 1596 patients examined. LASIK was not advised in 405 patients (25.4%). The most common reasons for rejecting LASIK were suboptimal central corneal thickness (25.9%), high myopia >-11.00 D (17.0%), keratoconus (15.5%), cataract (11.4%), and suspicious corneal topography (forme fruste keratoconus) (9.4%).

CONCLUSIONS

Patients who request refractive surgery have a variety of problems and attention must be given to these patients. Suboptimal corneal thickness, high amount of refractive error, and keratoconus were found to be the leading causes of not performing LASIK in Yemeni patients.

A comparison of the Goldmann applanation and non-contact (Keeler Pulsair EasyEye) tonometers and the effect of central corneal thickness in indigenous African eyes

The Keeler Pulsair EasyEye non-contact tonometer (NCT) was introduced into practice at Rachel Eye Center Abuja, Nigeria, where the patients are indigenous Africans. This was compared to the 'gold standard' Goldmann applanation tonometer (GAT) to determine if the instrument was accurate in Africans, with particular reference to the influence of central corneal thickness (CCT).

PATIENTS AND METHODS

174 eyes of 88 patients were analysed. Pachymetry was performed using Sonomed PacScan AP300, and GAT with the Haag Streit R-900. Pachymetric corrections of NCT (NCTc) and GAT (GATc) were carried out with the Sonomed algorithm. Pearson's correlation r, linear regression analysis, Student t-test and Bland-Altman analysis were used to compare the instruments.

RESULTS

Mean NCT readings were similar (17.36 mmHg) to mean GAT (17.42 mmHg; p = 0.769). GAT/NCT correlation coefficient, r, was 0.883 as compared with 0.868 for GATc/NCTc. The linear regression equation was GAT = 2.79 + 0.84*NCT (r(2) = 0.78). Forty-five per cent of differences were within 1 mmHg, while 79% were within 3 mmHg. This was similar to findings in some studies on Caucasians. Bland-Altman analysis however suggested that the spread of differences was wider than in those studies. Outliers (differences more than 5 mmHg) sometimes reflected difficulties encountered with GAT in routine practice. Mean CCT was 537.9 microm, (S.D. 38.4, 95% confidence interval 532.1-543.7 microm) and CCT appeared lower than in Caucasians. Both GAT and NCT IOP tended to rise with increasing CCT but NCT had a greater tendency to do so. Regression analysis suggested that NCT IOP increased by 0.6 mmHg for every 10 mum increase in CCT, compared to 0.4 mmHg for GAT. Thirty-eight per cent of the patients preferred NCT as opposed to 25% GAT.

CONCLUSIONS

The Keeler Pulsair EasyEye gives reliable measurements of IOP in African eyes but is significantly affected by CCT. Particularly in borderline cases where management decisions have to be taken, it may be necessary to have pachymetric corrections based on an NCT algorithm, which appears steeper than the GAT algorithm.