Neurophysiology of corneal neuropathic pain and emerging pharmacotherapeutics.

The altered activity generated by corneal neuronal injury can result in morphological and physiological changes in the architecture of synaptic connections in the nervous system. These changes can alter the sensitivity of neurons (both second-order and higher-order projection) projecting pain signals. A complex process involving different cell types, molecules, nerves, dendritic cells, neurokines, neuropeptides, and axon guidance molecules causes a high level of sensory rearrangement, which is germane to all the phases in the pathomechanism of corneal neuropathic pain. Immune cells migrating to the region of nerve injury assist in pain generation by secreting neurokines that ensure nerve depolarization. Furthermore, excitability in the central pain pathway is perpetuated by local activation of microglia in the trigeminal ganglion and alterations of the descending inhibitory modulation for corneal pain arriving from central nervous system. Corneal neuropathic pain may be facilitated by dysfunctional structures in the central somatosensory nervous system due to a lesion, altered synaptogenesis, or genetic abnormality. Understanding these important pathways will provide novel therapeutic insight.

Self-reported symptoms of ocular allergy and its comorbid factors among residents living near a landfill site in Ghana.

Residents close to landfill sites may be exposed to long-term emitted toxic compounds that may have effects on their eyes. The aim of this study was to determine the prevalence of symptomatic ocular allergy and its comorbid factors among residents living near a landfill site in Ghana. An exploratory cross-sectional design involving 400 inhabitants living around a landfill site was employed. The prevalence of symptomatic ocular allergy was 59.3%. In a bivariate analysis, comorbid conditions including respiratory disease, coughing, flu, cholera, skin disease, diarrhoea, and hypertension predicted symptomatic ocular allergy. However, only cholera remained a significant predictor of symptomatic ocular allergy in the multivariate analysis. Symptomatic ocular allergy was high among inhabitants around the landfill site in Ghana. While proper design and management of landfills in Ghana is crucial, further longitudinal and clinical studies are required to clinically establish the link between landfill and ocular allergy.

Comparison of anterior segment parameters in myopia with and without primary open-angle glaucoma.

PURPOSE: To compare anterior segment parameters between myopes with and without primary open-angle glaucoma using Pentacam scheimpflug tomography. METHODS: This was a single-center retrospective cross-sectional study. Records of patients examined with a Pentacam scheimpflug tomographer (Wavelight-Allegro Oculyzer, GmbH, Erlangen, Germany) were reviewed. Variables studied were recorded from the topographic map and included anterior chamber angle, anterior chamber volume, anterior chamber depth, keratometric readings, and corneal thickness. A general linear model for age-and spherical equivalent refraction-adjusted intergroup comparisons of the anterior segment parameters was conducted. RESULTS: The study included myopes previously diagnosed with primary open-angle glaucoma (POAG) [Mild defect, n = 81; Moderate-severe defect, n = 50] and non-glaucomatous myopes (n = 247). The results revealed a smaller anterior chamber angle, shallower anterior chamber depth, and flatter cornea curvature in the mildly glaucomatous group compared to the non-glaucomatous group (p < 0.05). Smaller anterior chamber angle, shallower anterior chamber depth, and thinner cornea thickness were also observed in the moderate-severely glaucomatous group compared to the non-glaucomatous group (p < 0.05). CONCLUSION: Glaucomatous damage in myopic patients with POAG was associated with comparatively small anterior chamber angle, shallow anterior chamber depth, flat cornea curvature, and thin cornea.

Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases.

Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.

Impact of Peripheral and Corneal Neuropathy on Markers of Ocular Surface Discomfort in Diabetic Chronic Kidney Disease.

SIGNIFICANCE: There is a reduction in corneal nerve fiber density and length in type 2 diabetes mellitus with chronic kidney disease compared with type 2 diabetes mellitus alone; however, this difference does not result in worse ocular surface discomfort or dry eye disease. PURPOSE: This study aimed to determine the clinical impact of corneal nerve loss on ocular surface discomfort and markers of ocular surface homeostasis in people with type 2 diabetes mellitus without chronic kidney disease (T2DM-no CKD) and those with type 2 diabetes mellitus with concurrent chronic kidney disease (T2DM-CKD). METHODS: Participants were classified based on estimated glomerular filtration rates into two groups: T2DM-CKD (n = 27) and T2DM-no CKD (n = 28). RESULTS: There was a significant difference between the T2DM-CKD and T2DM-no CKD groups in corneal nerve fiber density (14.9 ± 8.6 and 21.1 ± 7.1 no./mm 2 , respectively; P = .005) and corneal nerve fiber length (10.0 ± 4.6 and 12.3 ± 3.7 mm/mm 2 , respectively; P = .04). Fluorescein tear breakup time was significantly reduced in T2DM-CKD compared with T2DM-no CKD (8.1 ± 4.4 and 10.7 ± 3.8 seconds, respectively; P = .01), whereas ocular surface staining was not significantly different (3.5 ± 1.7 and 2.7 ± 2.3 scores, respectively; P = .12). In terms of ocular surface discomfort, there were no significant differences in the ocular discomfort score scores (12.5 ± 11.1 and 13.6 ± 12.1, respectively; P = .81) and Ocular Pain Assessment Survey scores (3.3 ± 5.4 and 4.3 ± 6.1, respectively; P = .37) between the T2DM-CKD and T2DM-no CKD. CONCLUSIONS: The current study demonstrated that corneal nerve loss is greater in T2DM-CKD than in T2DM-no CKD. However, these changes do not impact ocular surface discomfort or markers of ocular surface homeostasis.

Age- and sex-related differences in the measures of anterior segment parameters in a myopic clinical sample using Pentacam Scheimpflug tomography.

PURPOSE: To assess age-and sex-related differences of anterior segment parameters in a myopic clinical sample. METHODS: This clinic-based retrospective study involved eligible subjects grouped into myopia (i.e., low-to-moderate) and high myopia. Demographics and anterior segment parameters measures were recorded and analyzed. RESULTS: Some 153 eligible eyes were analyzed-98 myopia and 55 high myopia-comprising 87 males and 66 females. The mean ages and ranges were 28.47 years (SD = 9.59 years), 8-50 years, and 27.82 years (SD = 9.69 years), 10-51 years, for the myopia and the high myopia groups, respectively. The means of the spherical equivalents were - 3.02 D (SD = 1.46 D, range: - 0.50 to - 5.85 D), for the myopia group and - 10.42 D (SD = 5.50 D, range: - 6.00 to - 21.86 D) for the high myopia group. No significant difference was found between degree of myopia and anterior segment measures. Males had larger anterior chamber volume (mean 175.71 ± 26.27, range: 124-225 mm3); (P = 0.007) and deeper anterior chamber depth (3.73 ± 0.27, range: 3.06-4.41 mm) (P = 0.017) than females in the myopia group. Females also had significantly steeper anterior corneal curvature, Km (ant.) but flatter posterior corneal curvature, Km (post.), (- 6.31 ± 0.25, range - 7.00 to - 5.90 D) in both the myopia group [Km (ant.): 44.06 D ± 1.33 D, range: 41.30-47.10; Km (post.): - 6.31 D ± 0.25 D, range: - 7.00 to - 5.90; P = 0.008, P = 0.002, respectively] and the high myopia group [Km (ant.): 43.79 D ± 0.33 D, range: 41.00-47.10; Km (post.): - 6.22 D ± 0.30 D, range: - 6.80 to - 5.60; P = 0.034, P = 0.049, respectively]. Age was not correlated with the anterior segment parameters in both degrees of myopia. CONCLUSION: Sex has significant influence on the corneal curvature, anterior chamber volume and anterior chamber depth regardless of the degree of myopia.

Meibomian Gland Dysfunction and Lipid Profile: A Study Among Pregnant Women.

PURPOSE: This study aimed to estimate the frequency of meibomian gland dysfunction (MGD) and its associated factors among pregnant women. METHODS: This was a hospital-based cross-sectional study of consecutive pregnant women visiting the University of Cape Coast hospital's antenatal clinic. Meibomian gland assessment and tear function test were performed along with the administration of a symptom questionnaire. Correlation, analysis of variance, and logistic regression analyses were used to examine predictors of MGD. RESULTS: All 201 pregnant women who met the inclusion criteria and gave informed consent were included in the study. The mean age of the entire sample was 29.96 (±4.74) years. The frequency of MGD among the cohort of pregnant women was 22.9% (95% confidence interval, 17.4%-28.9%). Univariate logistic regression revealed that the following factors were significantly associated with MGD: high-density lipoprotein (HDL) (odds ratio [OR] 1.017; 95% confidence interval [CI], 1.001-1.034; P=0.042), total cholesterol (TC) (OR 1.009; 95% CI, 1.003-1.016; P=0.006), and low-density lipoprotein (LDL) (OR 1.008; 95% CI, 1.00-1.016; P=0.049). In multivariate analysis, the model confirmed that MGD was not significantly associated with TC, LDL, and HDL. CONCLUSIONS: In summary, this study showed a high frequency of MGD in pregnant women but comparable with that reported in the normal population. Clinicians examining pregnant women for dry eye disease may need to pay attention to other causative instigators aside MGD to enable the clinicians to make an appropriate etiology-based diagnosis.

Meibomian Gland Dysfunction in a Youthful Clinical Sample in Ghana.

SIGNIFICANCE: This study showed a high frequency of nonobvious obstructive meibomian gland dysfunction, which can be detected only via the expression of the meibomian glands. The study advocates that meibomian gland expressibility should be a routine part of the clinical examination of patients especially those with dry eyes to avoid missing meibomian gland dysfunction among a youthful population. PURPOSE: The aim of this study was to estimate the frequency of meibomian gland dysfunction including asymptomatic and symptomatic meibomian gland dysfunction and obvious and nonobvious obstructive meibomian gland dysfunction among a youthful population in Ghana. METHODS: This was a clinic-based prospective cross-sectional study of consecutive patients visiting the University of Cape Coast Optometric clinic for comprehensive eye examination. RESULTS: Two hundred fifteen clinical subjects consented to participate in the study. Mean age of the entire sample was 21.9 (±3.8) years with an age range of 17 to 40 years. One hundred five males and 107 females participated. Frequency of meibomian gland dysfunction among the sample was 25.5% (95% confidence interval [CI], 19.8 to 31.6%). Frequencies of asymptomatic and symptomatic meibomian gland dysfunction were 10.1% and 15.4%, respectively. Frequencies of obvious and nonobvious obstructive meibomian gland dysfunction were 0.9% and 24.6%, respectively. In univariate logistic regression analysis, age (odds ratio, 1.246; 95% CI, 1.037 to 1.496; P = .019) was significantly associated, but sex (odds ratio, 1.315; 95% CI, 0.707 to 2.446; P = .387) was not significantly associated, with meibomian gland dysfunction. There was a statistically significant difference in the mean corneal staining scores between meibomian gland dysfunction subjects and non-meibomian gland dysfunction subjects (t = 3.51, P = .01). There was also a statistically significant difference in the mean tear breakup time between meibomian gland dysfunction subjects and non-meibomian gland dysfunction subjects (t = 4.44, P < .001). CONCLUSIONS: Because of the high frequency of nonobvious obstructive meibomian gland dysfunction, reliance on overt posterior lid margin abnormalities for the diagnosis of meibomian gland dysfunction may lead to underdiagnosis of meibomian gland dysfunction among clinicians in a youthful population.

Impact of Dry Eye on Psychosomatic Symptoms and Quality of Life in a Healthy Youthful Clinical Sample.

OBJECTIVE: To determine the impact of dry eye on quality of life, depression, anxiety, and stress in a healthy youthful clinical sample. METHODS: This was a clinic-based cross-sectional study. Subjects were patients visiting the University of Cape Coast Eye Clinic for comprehensive eye examination. The age range for recruitment into the study was 16 to 35 years. Eligible participants completed three questionnaires namely the Ocular Surface Disease Index (OSDI), short version of the depression, anxiety, and stress scale (DASS-21), dry eye quality of life score (DEQS) questionnaire. All eligible participants underwent clinical assessment including meibomian gland expressibility, corneal staining, tear breakup time, and Schirmer 1 test. The Spearman correlation coefficient was used to determine the relationship between variables. Univariate and multivariate analyses of variance were used to determine the impact of the OSDI score on DASS-21 subscales scores and the dry eye quality of life scores. RESULTS: All 211 subjects who met the inclusion criteria were included in the analysis. The mean age for the entire sample was 21.6±3.0 years with a range of (17-31) years. Spearman correlation coefficient showed a statistically significant association between OSDI scores and DEQSs (P<0.001), anxiety scores (P<0.001), depression scores (P<0.001), and stress scores (P<0.001). Spearman correlation coefficient showed no statistically significant association between clinical test results and quality of life scores (P>0.05), DASS-21 subscales scores (P>0.05), except anxiety subscale and meibomian gland expressibility score (P=0.026). There were no statistically significant association between clinical test results and OSDI scores (P>0.05) except for the tear breakup time (P=0.018). Using Pillai's trace in the multivariate analysis of variance (MANOVA), there was a significant effect of OSDI severity classification on depression, anxiety, and stress subscales scores of the DASS-21, V=0.37, F(3, 207)=9.67, P<0.001. Furthermore, separate univariate analyses of variances on the outcome variables revealed a significant effect of OSDI severity classification on depression F(3, 207)=35.24, P<0.001, anxiety F(3, 207)=25.27, P<0.001, and stress F(3, 207)=13.08, P<0.001. The MANOVA was followed up with a discriminant analysis, which revealed three discriminant functions. When subjects were classified according to the OSDI grading of severity, there were a statistically significant difference between all levels of severity dry eye symptoms for the DEQSs (F(3, 207) = 63.9.3 P<0.001, η=0.48). CONCLUSION: The study showed that the severity of dry eye symptoms impacted on psychosomatic symptoms and quality of life. The study also revealed that the severity of dry eye symptoms impacted more on the depressive symptoms compared with other psychosomatic symptoms in this youthful clinical sample.

Rasch Analysis of the Standard Patient Evaluation of Eye Dryness Questionnaire.

BACKGROUND: This study sought to investigate, if the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire acts as a measure of dry eye severity and whether it is unidimensional using Rasch analysis. METHODS: This is a hospital-based cross-sectional study. The study included 127 patients with glaucoma with either a clinical diagnosis of dry eye or an Ocular Surface Disease Index score of ≥13. Participants completed questionnaires (SPEED) delivered directly to them. RESULTS: A total of 127 participants met the inclusion criteria and were included in the analysis. Category response analysis revealed that the average logit measures for the response category increased with higher response category from -4.93 to +5.41 logit. Item infit mean square statistics of the individual items ranged from 0.57 to 1.33, with a mean of 0.99±0.2. The individual item outfit mean square ranged from 0.58 to 1.36, with a mean of 1.02±0.0. The person separation index (PSI) and separation reliability of the SPEED were 2.23 and 0.83, respectively. Principal component analysis (PCA) of the standardized model residuals revealed evidence of multidimensionality, with first contrast eigenvalue of 2.5 and the second contrast eigenvalue of 1.7. Because fit statistics of all items were within 0.5 to 1.7 and considered adequate for clinical observations, no item was removed. However, the six items of the SPEED that asked about the commonest dry eye symptoms as reported by patients with dry eye were analyzed separately to determine how they behaved. The item fit statistics of these six items were within the range of 0.6 to 1.4. The outfit statistics range from 0.62 to 1.26, with a mean of 1.00±0.1. The infit statistics range from 0.61 to 1.24, with a mean of 0.99±0.2. The PSI and reliability were 2.2 and 0.83, respectively. Finally, PCA of the standardized model residuals revealed no evidence of multidimensionality, with first contrast eigenvalue of 2.0. CONCLUSION: In summary, this study showed that the SPEED had an ordered response category and was a measure of dry eye severity. However, PCA of the standardized model residuals revealed evidence of multidimensionality. A proposed six-item SPEED was unidimensional and was also a measure of disease severity. Hence, the SPEED questionnaire score may be used as a measure of dry eye severity in clinical practice and epidemiological studies.

Symptomatic Dry Eye and Its Associated Factors: A Study of University Undergraduate Students in Ghana.

BACKGROUND: To estimate the prevalence and risk factors of symptomatic dry eye disease (DED) among undergraduate students in a Ghanaian university. METHODS: This cross-sectional study included 700 undergraduate students of the University of Cape Coast, aged 18 to 34 years. Participants completed questionnaires delivered directly to randomly and systematically selected subjects to detect symptomatic dry eye and its predictive factors. Symptomatic dry eye was defined as any reported symptom on the Standard Patient Evaluation Eye Dryness (SPEED) questionnaire reported as often or constant or if any symptom on the Ocular Surface Disease Index (OSDI) was reported as most of the time or all of the time. Furthermore, OSDI ≥13 and SPEED ≥6 were used to defined symptomatic dry eye and prevalence were also estimated with these criteria as secondary measures. Current symptoms of dry eye and possible risk factors such as age, gender, current alcohol drinking, use of oral contraceptives, use of computer more than an hour daily, environmental conditions, allergies, and self-medication with over-the-counter eye drops were the main outcome measures. We used logistic regression analysis to examine the associations between dry eye and its predictive factors. RESULTS: Of the 700 participants, 650 completed the questionnaire. The prevalence of symptomatic dry eye was 44.3% (95% confidence interval [CI], 40.6%-48.2%). There was a significant association between symptomatic dry eye and discomfort with eyes in windy conditions (χ=110.1; df=4; P<0.001), areas with low humidity (χ=91.6; df=4; P<0.001), and air-conditioned rooms (χ=89.0; df=4; P<0.001). Self-medication with over-the-counter eye drops (OR 4.20; 95% CI, 2.61-6.74; P<0.001), any allergies (OR 2.46; 95% CI, 1.42-4.29; P=0.001), and use of oral contraceptives (OR 4.04; 95% CI, 1.02-16.01; P=0.047) were predictive factors of symptomatic dry eye. Sex was predictive in univariate analysis but was not significantly associated in multivariate analysis. CONCLUSIONS: The prevalence of symptomatic dry eye among undergraduate students in Ghana is high and it is associated with self-medication with over-the-counter eye drops, allergies, use of oral contraceptive, windy conditions, very low humid areas, air-conditioned rooms, and sex. Relevant input directed against modifiable risks factors may have a positive impact on the well-being of undergraduate students in Ghana.

Knowledge and awareness of ocular allergy among undergraduate students of public universities in Ghana.

BACKGROUND: Ocular allergy is a growing public health problem that greatly impacts the day-to-day life of sufferers and their families. Other aspects of their activities of daily living such as schooling, professional, and social life are affected hence an increased awareness and knowledge of ocular allergies, their detection and treatment is paramount. This study was to assess the level of knowledge and awareness of ocular allergy among undergraduate students of public universities in Ghana. METHODS: A descriptive cross sectional survey was conducted among 1000 students from three selected public universities in Ghana. Each respondent completed a questionnaire that had questions concerning awareness and knowledge of ocular allergy. RESULTS: Out of the 1000 students, 347 (34.7 %) were aware of ocular allergy. Of these 347 students, the level of knowledge of ocular allergy was generally low. Majority of the students had their source of information about ocular allergy from the media and the internet. There was statistical significant association among awareness of ocular allergy, sources of information and programme of study (p < 0.001). CONCLUSION: Level of awareness among university students is generally low. Students' programmes of study influenced their knowledge of ocular allergy. Public health measures are recommended to help educate students on the prevention and control of ocular allergy as well as the complications associated with this condition.

Prevalence and risk factors of Vernal Keratoconjunctivitis among a Ghanaian clinical cohort: A case-control study.

Background: Vernal Keratoconjunctivitis (VKC) has been determined to be highly prevalent in countries within the tropical climate region. However, little evidence from studies conducted within this region has been put forward to support this claim. Aim: To determine the prevalence and risk factors of VKC among a Ghanaian clinical cohort. Methods: A 3-year case-control study was conducted in a tertiary eye care institution, and medical records of patients who had been diagnosed of VKC between 2018 and 2021 were reviewed. Results: Medical records of 3800 patients were reviewed. Some 359 cases of VKC were identified, with a population prevalence rate of 9.45%. Males comprised 57.1% of the population with VKC, with a male-to-female ratio of 1.33:1. The disease was more prevalent (40.8%) in children (≤17 years), and the overall odds of incidence decreased by 10% for a unit increase in age. Age and sex-adjusted models revealed significant positive associations between Keratoconus [aOR = 40.760, 95% CI -5.948 to 339.937], Rhinitis [cOR = 5.183, 95% CI -2.074 to 12.022] and VKC. However, the incidence of VKC was relatively less expressive among pterygium cases [cOR = 0.315, 95% CI -0.077 to 0.846]. Conclusion: VKC is highly prevalent among children and is often associated with comorbidities of atopic origin that exacerbate the impact of the disease among this vulnerable population. It is imperative that clinicians provide holistic care for children with VKC.

Impact of SGLT2 Inhibitors on Corneal Nerve Morphology and Dendritic Cell Density in Type 2 Diabetes.

PURPOSE: This study aims to determine the effects of SGLT2 inhibitors on corneal dendritic cell density and corneal nerve measures in type 2 diabetes. METHODS: Corneal dendritic cell densities and nerve parameters were measured in people with type 2 diabetes treated with SGLT2 inhibitors (T2DM-SGLT2i) [n = 23] and those not treated with SGLT2 inhibitors (T2DM-no SGLT2i) [n = 23], along with 24 age and sex-matched healthy controls. RESULTS: There was a reduction in all corneal nerve parameters in type 2 diabetes groups compared to healthy controls (All parameters: p < 0.05). No significant differences in corneal nerve parameters were observed between T2DM-SGLT2i and T2DM-no SGLT2i groups (All parameters: p > 0.05). Central corneal dendritic cells were significantly reduced [mature (p = 0.03), immature (p = 0.06) and total (p = 0.002)] in the T2DM-SGLT2i group compared to the T2DM-no SGLT2i group. Significantly, higher mature (p = 0.04), immature (p = 0.004), total (p = 0.002) dendritic cell densities in the T2DM-no SGLT2i group were observed compared to the healthy controls. In the inferior whorl, no significant difference in immature (p = 0.27) and total dendritic cell densities (p = 0.16) between T2DM-SGLT2i and T2DM-no SGLT2i were observed except mature dendritic cell density (p = 0.018). No differences in total dendritic cell density were observed in the central (p > 0.09) and inferior whorl (p = 0.88) between T2DM-SGLT2i and healthy controls. CONCLUSION: The present study showed a reduced dendritic cell density in people with type 2 diabetes taking SGLT2 inhibitors compared to those not taking these medications.

Risk of major myopia-associated non-communicable ocular health disorders in Ghana.

OBJECTIVE: To assess the differential association of myopia with major non-communicable ocular diseases in an African clinical cohort. METHODS: A five-year hospital-based retrospective study of myopia cases. Patients' folders, Optical Coherence Tomography scans, and fundus photographs were reviewed for the abstraction of relevant data. Only records that employed recognized standards and classification systems for diagnosing and staging the various ocular conditions were included. Demographic characteristics, non-cycloplegic objective refractive findings, and non-communicable eye diseases were retrieved from the records. Myopia-associated risk factors were then determined using logistic regression and correlation. RESULTS: Some 16018 patients (32027 eyes) met the inclusion criteria for at least one eye comprising 50.8% males (n = 8137) and 49.2% females (n = 7881). The mean age of the patients was 43.14 ± 17.88 years (range: 2-98 years). The mean spherical equivalent± Standard deviation for myopia was -2.30±3.23 DS (range: -0.50 to -25DS). Binary logistic regression analysis showed that myopic eyes had a higher odd of AC (OR, 0.53; 95% CI, 0.50-0.57), POAG (OR, 6.0; 95% CI, 5.26-6.82), DR (OR, 10.70; 95% CI, 3.91-29.27) and cataracts (OR, 20; 95% CI, 15.32-26.20) but not dry eye (OR, 0.74, 95% CI, 0.68-0.81), macular degeneration and pterygium (OR, 0.36; 95% CI, 0.32-0.40). CONCLUSION: Africans with myopia are more at risk of developing allergic conjunctivitis, cataracts, POAG, and DR but not for dry eye, macular degeneration, and pterygium.

Conjunctival microcirculation in ocular and systemic microvascular disease.

The conjunctival microcirculation is an accessible complex network of micro vessels whose quantitative assessment can reveal microvascular haemodynamic properties. Currently, algorithms for the measurement of conjunctival haemodynamics use either manual or semi-automated systems, which may provide insight into overall conjunctival health, as well as in ocular and systemic disease. These algorithms include functional slit-lamp biomicroscopy, laser doppler flowmetry, optical coherence tomography angiography, orthogonal polarized spectral imaging, computer-assisted intravitral microscopy, diffuse reflectance spectroscopy and corneal confocal microscopy. Furthermore, several studies have demonstrated a relationship between conjunctival microcirculatory haemodynamics and many diseases such as dry eye disease, Alzheimer's disease, diabetes, hypertension, sepsis, coronary microvascular disease, and sickle cell anaemia. This review aims to describe conjunctival microcirculation, its characteristics, and techniques for its measurement, as well as the association between conjunctival microcirculation and microvascular abnormalities in disease states.

Chronic Kidney Disease Has No Impact on Tear Film Substance P Concentration in Type 2 Diabetes.

PURPOSE: The study aimed to ascertain the potential effects of chronic kidney disease (CKD) on substance P concentration in the tear film of people with type 2 diabetes. METHODS: Participants were classified into two groups: type 2 diabetes with concurrent chronic kidney disease (T2DM-CKD (n = 25)) and type 2 diabetes without chronic kidney disease (T2DM-no CKD (n = 25)). Ocular surface discomfort assessment, flush tear collection, in-vivo corneal confocal microscopy, and peripheral neuropathy assessment were conducted. Enzyme-linked immunosorbent assays were utilized to ascertain the levels of tear film substance P in collected flush tears. Correlation analysis, hierarchical multiple linear regression analysis, and t-tests or Mann-Whitney U tests were used in the analysis of data for two-group comparisons. RESULTS: There was no substantial difference between the T2DM-CKD and T2DM-no CKD groups for tear film substance P concentration (4.4 (0.2-50.4) and 5.9 (0.2-47.2) ng/mL, respectively; p = 0.54). No difference was observed in tear film substance P concentration between the low-severity peripheral neuropathy and high-severity peripheral neuropathy groups (4.4 (0.2-50.4) and 3.3 (0.3-40.7) ng/mL, respectively; p = 0.80). Corneal nerve fiber length (9.8 ± 4.6 and 12.4 ± 3.8 mm/mm2, respectively; p = 0.04) and corneal nerve fiber density (14.7 ± 8.5 and 21.1 ± 7.0 no/mm2, respectively; p < 0.01) were reduced significantly in the T2DM-CKD group compared to the T2DM-no CKD group. There were significant differences in corneal nerve fiber density (21.0 ± 8.1 and 15.8 ± 7.7 no/mm2, respectively; p = 0.04) and corneal nerve fiber length (12.9 ± 4.2 and 9.7 ± 3.8 mm/mm2, respectively; p = 0.03) between the low- and high-severity peripheral neuropathy groups. CONCLUSION: In conclusion, no significant difference in tear film substance P concentration was observed between type 2 diabetes with and without CKD. Corneal nerve loss, however, was more significant in type 2 diabetes with chronic kidney disease compared to type 2 diabetes alone, indicating that corneal nerve morphological measures could serve greater utility as a tool to detect neuropathy and nephropathy-related corneal nerve changes.

Efficacy of intravitreal bevacizumab on diabetic macular oedema in an African population.

PURPOSE: To evaluate the short-term effect of intravitreal bevacizumab (avastin) injection on visual outcomes of patients with diabetic macular oedema. METHODS: A retrospective cross-sectional study was conducted to evaluate 39 eyes of thirty-nine patients (mean age ± SD: 61.4 ± 15.0 years) that received intravitreal bevacizumab injection (1.25 mg in 0.05 ml) as treatment for diabetic macular oedema between January 2014 and July 2019 in Ghana. Data on visual acuity and central macular thickness before treatment and 6 weeks post-treatment were collected and analysed using paired t-test. Ordinary least squares linear regression analysis was also conducted to determine the relationship between improvement in visual acuity and central macular thickness after treatment and other predictor variables. RESULTS: The mean ± SD visual acuity (LogMAR-equivalent of Snellen) of patients with diabetic macular oedema significantly improved from 0.84 ± 0.58 LogMAR before treatment to 0.69 ± 0.58 LogMAR at 6 weeks post-treatment (mean difference: 0.15 ± 0.32 LogMAR; 95% CI: 0.04 to 0.25; p = 0.01). Mean macular thickness ± SD on the other hand, reduced significantly (p < 0.001) from 316.54 ± 75.35 µm before treatment to 275.54 ± 57.43 µm after treatment. While age and worse pre-treatment visual acuity predicted improvement in visual acuity after treatment, a higher central macular thickness before treatment predicted an improvement in central macular thickness after intravitreal bevacizumab injection. CONCLUSION: Treatment with intravitreal bevacizumab injection produces short-term improvement in vision and reduction in central macular thickness in African patients with diabetic macular oedema.

Candidate Molecular Compounds as Potential Indicators for Meibomian Gland Dysfunction.

Meibomian gland dysfunction (MGD) is the leading cause of dry eye disease throughout the world. Studies have shown that several molecules in meibum, including but not limited to interleukins, amino acids, cadherins, eicosanoids, carbohydrates, and proteins, are altered in meibomian gland dysfunction compared with healthy normal controls. Some of these molecules such as antileukoproteinase, phospholipase A2, and lactoperoxidase also show differences in concentrations in tears between meibomian gland dysfunction and dry eye disease, further boosting hopes as candidate biomarkers. MGD is a complex condition, making it difficult to distinguish patients using single biomarkers. Therefore, multiple biomarkers forming a multiplex panel may be required. This review aims to describe molecules comprising lipids, proteins, and carbohydrates with the potential of serving various capacities as monitoring, predictive, diagnostic, and risk biomarkers for meibomian gland dysfunction.

Role of ocular surface neurobiology in neuronal-mediated inflammation in dry eye disease.

Inflammation is the consequence of dry eye disease regardless of its etiology. Several injurious or harmless processes to the ocular surface neurons promote ocular surface neurogenic inflammation, leading to the vicious cycle of dry eye disease. These processes include the regular release of neuromediators during the conduction of ocular surface sensations, hyperosmolarity-induced ocular surface neuronal damage, neuro-regenerative activities, and neuronal-mediated dendritic cell activities. Neurogenic inflammation appears to be the main culprit, instigating the self-perpetuating inflammation observed in patients with dry eye disease.