Distribution of corneal spherical aberration in a Tanzanian population

Purpose

To investigate the distribution of corneal spherical aberration (SA) in Tanzanian people of African descent, and to examine the correlation between corneal SA and ocular parameters.

Design

Cross-sectional population-based study.

Methods

Residents aged 40 years and older in three villages in the Mkuranga district in Tanzania were enlisted as study participants. Corneal higher-order aberrations (HOAs) for the right eye were measured with a wavefront analyzer (KR-1W, Topcon) and calculated for the central 6.0-mm zone. Corneal curvature radius (CR), corneal astigmatism, and axial length (AL) were also measured and their correlation with corneal SA was assessed.

Results

The right eyes of 657 participants (336 male, 321 female) were analyzed. The mean age of the subjects was 57.2 ± 10.3 years (mean ± SD). The mean corneal SA (Zernike spherical aberration coefficient C₄⁰) was 0.188 ± 0.095 μm (-0.242 to 0.613). The SAs in about three-quarters of all subjects were between 0.10 and 0.30 μm. The root mean squares of total corneal HOAs and the third- and fourth-order aberrations were 0.629 ± 0.250 μm, 0.539 ± 0.236 μm, and 0.269 ± 0.110 μm, respectively. Corneal SA showed weak significant correlations with CR (Spearman’s rank correlation coefficient, r = -0.177, p < 0.001), corneal astigmatism (r = -0.142, p < 0.001), AL (r = -0.168, p < 0.001), and age (r = -0.085, p < 0.05).

Conclusions

This finding may be beneficial for selecting aspheric intraocular lens in this population.

Hypertensive retinopathy and associated factors among nondiabetic chronic kidney disease patients seen at a tertiary hospital in Tanzania: a cross-sectional study

Background: Hypertensive retinopathy is a known marker of cardiovascular disease, and among unselected patients with chronic kidney disease (CKD) more severe retinopathy has been associated with lower estimated glomerular filtration rate (eGFR). This association has, however, not been widely studied among nondiabetic hypertensive patients with CKD, especially in sub-Saharan Africa. We aimed to determine the prevalence and severity of hypertensive retinopathy and its relationship with eGFR among nondiabetic CKD patients seen at Muhimbili National Hospital in Dar es Salaam, Tanzania. Methods: A hospital-based cross-sectional study was conducted among nondiabetic CKD adult (≥18 years) patients with hypertension. A structured questionnaire was used to record patients' demographic characteristics and their cardiovascular risk profile. eGFR was calculated using the Modification of Diet in the Renal Disease (MDRD) equation and only patients with CKD stage 3 or more were enrolled in the study. Grading of retinopathy was done using the Keith-Wagener classification. Results: In total, 224 patients fulfilled the inclusion criteria and were enrolled. Their mean age was 45.8±14.1 years, and 59.4% were men. The proportions of patients with stage 3, 4, and 5 CKD were 21.4%, 19.6%, and 58.9%, respectively. Hypertensive retinopathy was present in 157 (70.1%) patients and the proportions with grade I, grade II, grade III, and grade IV retinopathy were 17.9%, 18.8%, 19.6%, and 13.8%, respectively. The severity of retinopathy increased with decreasing levels of eGFR, and in multivariate logistic regression analysis, factors found to be independently associated with ≥grade II hypertensive retinopathy were more severe CKD, higher hypertension grades, and alcohol use, all p<0.05. Conclusion: The prevalence of hypertensive retinopathy is high among nondiabetic CKD patients seen at a tertiary hospital in Tanzania and is independently associated with CKD severity. Retinopathy grade can be used as a marker of CKD severity among these patients.

Survey on acute and chronic complications in children and adolescents with type 1 diabetes at Muhimbili National Hospital in Dar es Salaam, Tanzania

OBJECTIVE

The purpose of this study was to assess glycemic control and complications of type 1 diabetes in children and adolescents in Tanzania.

RESEARCH DESIGN AND METHODS

This demographic and clinical survey included 99 children aged between 5 and 18 years attending Muhimbili National Hospital Clinic for Diabetes. A structured questionnaire was used for evaluating socioeconomic data and for estimation of the prevalence of acute complications occurring over the last 6 months. The prevalences of retinopathy and diabetic nephropathy were determined by fundus ophthalmoscopy and by microalbuminuria, respectively.

RESULTS

All of these children were treated with a conventional insulin regimen. The mean +/- SD duration of diabetes was 4.76 +/- 3.58 years. Only 1 child (1%) had good glycemic control (A1C <7.5%), 60 children (60.6%) had moderate glycemic control (A1C 7.5-10%), 14 children (14.1%) had poor glycemic control (A1C >10-12.5%), and 24 children (24.2%) had very poor glycemic control (A1C >12.5%). At onset of diabetes, 75% of children presented with diabetic ketoacidosis (DKA); 89 children (89.80%) had at least one episode of DKA, and 55 children (55.67%) had symptomatic hypoglycemic episodes. Microalbuminuria was present in 29 (29.3%) and retinopathy in 22 (22.68%) children.

CONCLUSIONS

Although there are some methodological limitations, this survey highlights the difficulties of achieving good metabolic control and the high prevalence of acute and chronic complications in Tanzanian children with type 1 diabetes. These results clearly show that major efforts are needed to improve quality of care in children with type 1 diabetes in Tanzania.