A Low-Fat/Sucrose Diet Rich in Complex Carbohydrates Reverses High-Fat/Sucrose Diet-Induced Corneal Dysregulation.

High-fat/sucrose diet feeding in mice causes loss of corneal nerve function and impairs corneal wound healing. While changing to a diet with a low fat/sugar composition and enrichments in complex carbohydrates mitigates the reduction in nerve function, it remains to be determined if it has an effect on corneal wound healing. In this study, 6-week-old C57BL/6 male mice were fed either a normal diet or a high-fat/sucrose diet for 20 weeks. A third group (diet reversal) was placed on a high-fat/sucrose diet for 10 weeks followed by a normal diet for an additional 10 weeks. A central corneal epithelial abrasion wound was created, and wound closure was monitored. Neutrophil and platelet recruitment was assessed by immunofluorescence microscopy. Mice fed the high-fat/sucrose diet-only had greater adiposity (p < 0.005) than normal diet-only fed mice; diet reversal markedly reduced adiposity. Following corneal abrasion, wound closure was delayed by ~6 h (p ≤ 0.01) and, at 30 h post-wounding, fewer neutrophils reached the wound center and fewer extravascular platelets were present at the limbus (p < 0.05). Diet restored normal wound closure and neutrophil and platelet influx in the injured cornea. These data suggest compositional changes to the diet may be an effective diet-based therapeutic strategy for maintaining or restoring corneal health.

Prevalence of Dry Eye Disease in Africa: A Systematic Review and Meta-analysis.

SIGNIFICANCE: Dry eye disease is a significant public health problem globally. The magnitude of the dry eye disease problem in Africa is, however, unknown. This study provides important and lacking information on dry eye disease in Africa. PURPOSE: This study aimed to estimate the prevalence of dry eye disease in Africa. METHODS: A systematic online literature search was conducted for articles on dry eye disease in Africa. Meta-analysis was conducted to estimate the prevalence of dry eye disease in Africa and meta-regression to explore the association between dry eye and sex, age, study population, country of study, and type of study. RESULTS: The overall prevalence estimate of dry eye disease in Africa was 42.0% (95% confidence interval [CI], 30.7 to 53.8%). The prevalence rates of dry eye disease in male and female individuals were 42.1% (95% CI, 28.5 to 56.3%) and 44.4% (95% CI, 30.2 to 59.0%), respectively; in South Africa, Ghana, Nigeria, and Egypt, the rates were 54.9% (95% CI, 39.0 to 70.4%), 38.3% (95% CI,17.7 to 61.4%), 41.4% (95% CI, 20.1 to 64.5%), and 34.9% (95% CI, 13.2 to 60.6%) respectively; and in school, hospital, and population-based studies, the rates were 51.6% (95% CI, 40.6 to 62.6%), 38.7% (95% CI, 21.9 to 57.0%), and 37.4% (95% CI, 27.4 to 48.0%). respectively. The prevalence rates of dry eye disease were 36.9% (95% CI, 26.7 to 51.1%) in a "normal" population and 44.2% (95% CI, 18.0 to 67.9%) in a population with known risk conditions. There were no associations between dry eye disease prevalence and sex (P = .88), type of study (P = .42), country of study (P = .33), study population (P = .59), and the diagnostic criteria used (P = .36). CONCLUSIONS: There seems to be a significant dry eye disease burden in Africa. This may pose an important public health problem that requires immediate attention and action. More epidemiological studies in Africa are needed to fully understand this problem to inform policy decisions.

Association between diabetes and keratoconus-a systematic review and meta-analysis.

PURPOSE: To assess the association between diabetes mellitus and keratoconus. METHODS: PubMed, Google Scholar, Web of Science, and Scopus databases were searched for literature on the association between diabetes and keratoconus. The last literature search was conducted on April 4, 2021. A secondary form of the literature search was conducted by manually scanning the reference list of retrieved eligible articles. Included studies were cohort, case-control, or cross-sectional study design that used odds ratio or risk ratio to evaluate the relationship between keratoconus and diabetes. Egger's test was used to assess the presence of publication bias. The quality of eligible studies was assessed using the Newcastle-Ottawa Scale. RESULTS: Nine studies (six case-control and three cohort studies) published between 2000 and 2021 were included. The total number of keratoconus patients and controls were 27,311 and 53,732. respectively. Meta-analysis revealed no significant association between diabetes mellitus and keratoconus; the pooled odds ratio was 0.87 (95% confidence interval: 0.66-1.14; p = 0.314). There was significant heterogeneity (Q (df = 7) = 33.36, p < 0.001;I2 = 79.01, p < 0.001). Age of participants (p < 0.0001), study design (p < 0.001), and sample size (p = 0.024) were significant sources of heterogeneity. There was no evidence of publication bias. CONCLUSION: The current meta-analysis revealed no significant association between diabetes mellitus and keratoconus. Well-designed longitudinal prospective studies are, however, needed to investigate any association between diabetes mellitus and keratoconus.

Dissociation between Corneal and Cardiometabolic Changes in Response to a Time-Restricted Feeding of a High Fat Diet.

Mice fed a high fat diet (HFD) ab libitum show corneal dysregulation, as evidenced by decreased sensitivity and impaired wound healing. Time-restricted (TR) feeding can effectively mitigate the cardiometabolic effects of an HFD. To determine if TR feeding attenuates HFD-induced corneal dysregulation, this study evaluated 6-week-old C57BL/6 mice fed an ad libitum normal diet (ND), an ad libitum HFD, or a time-restricted (TR) HFD for 10 days. Corneal sensitivity was measured using a Cochet-Bonnet aesthesiometer. A corneal epithelial abrasion wound was created, and wound closure was monitored for 30 h. Neutrophil and platelet recruitment were assessed by immunofluorescence microscopy. TR HFD fed mice gained less weight (p < 0.0001), had less visceral fat (p = 0.015), and had reduced numbers of adipose tissue macrophages and T cells (p < 0.05) compared to ad libitum HFD fed mice. Corneal sensitivity was reduced in ad libitum HFD and TR HFD fed mice compared to ad libitum ND fed mice (p < 0.0001). Following epithelial abrasion, corneal wound closure was delayed (~6 h), and neutrophil and platelet recruitment was dysregulated similarly in ad libitum and TR HFD fed mice. TR HFD feeding appears to mitigate adipose tissue inflammation and adiposity, while the cornea remains sensitive to the pathologic effects of HFD feeding.

An Epithelial Abrasion Model for Studying Corneal Wound Healing.

The cornea is critical for vision, accounting for about two-thirds of the refractive power of the eye. Crucial to the role of the cornea in vision is its transparency. However, due to its external position, the cornea is highly susceptible to a wide variety of injuries that can lead to the loss of corneal transparency and eventual blindness. Efficient corneal wound healing in response to these injuries is pivotal for maintaining corneal homeostasis and preservation of corneal transparency and refractive capabilities. In events of compromised corneal wound healing, the cornea becomes vulnerable to infections, ulcerations, and scarring. Given the fundamental importance of corneal wound healing to the preservation of corneal transparency and vision, a better understanding of the normal corneal wound healing process is a prerequisite to understanding impaired corneal wound healing associated with infection and disease. Toward this goal, murine models of corneal wounding have proven useful in furthering our understanding of the corneal wound healing mechanisms operating under normal physiological conditions. Here, a protocol for creating a central corneal epithelial abrasion in mouse using a trephine and a blunt golf club spud is described. In this model, a 2 mm diameter circular trephine, centered over the cornea, is used to demarcate the wound area. The golf club spud is used with care to debride the epithelium and create a circular wound without damaging the corneal epithelial basement membrane. The resulting inflammatory response proceeds as a well-characterized cascade of cellular and molecular events that are critical for efficient wound healing. This simple corneal wound healing model is highly reproducible and well-published and is now being used to evaluate compromised corneal wound healing in the context of disease.

Assessment of Ocular Surface Disease in Glaucoma Patients in Ghana.

PRECIS: Dry eye disease (DED) observed in this study is associated with ocular surface abnormalities as shown by specific dry eye tests. Changes in tear quality may be responsible for dry eye symptoms among the participants. PURPOSE: This study sought to evaluate DED in glaucoma patients in Ghana. MATERIALS AND METHODS: This was a hospital-based descriptive cross-sectional study involving glaucoma patients on topical glaucoma treatment for at least 6 months. The medical records of participants were thoroughly reviewed for information on demographics, ocular history, medical history, number of topical antiglaucoma medications used within the last 6 months, and any other ophthalmic medications used by the participants. An Ocular Surface Disease Index (OSDI) questionnaire was administered to each participant, after which Schirmer test and tear break-up time (TBUT) were performed on each participant in a controlled environment. RESULTS: A total of 100 individuals participated in the study. The mean±SD age of participants was 60.44±14.05 years. The majority (60.0%) of the participants were females and 55.0% of participants used 2 or more topical antiglaucoma medication. Of the participants, 81.0% reported subjective dry eye symptoms. Schirmer test and TBUT showed that 55.0% and 87.0% of the participants had decreased tear production and abnormal tear quality, respectively. Multiple logistic regression showed a significant association between age and abnormal OSDI (P=0.037), Schirmer test (P=0.003), and TBUT (P=0.042); the number of topical glaucoma medications and OSDI (P=0.016) and Schirmer test (P=0.009). The prevalence of DED was 23.0%. Increasing age was associated with an ∼7 times higher odds of having DED (P=0.0019), using >2 glaucoma medications with ∼4.5 times higher odds of having DED (P=0.001), 5 or more years of glaucoma medication use with ∼4 times higher odds of DED (P=0.009), and both benzalkonium chloride and sodium chlorite as preservative was associated with ∼3.5 times higher odds of DED (P=0.047). CONCLUSION: DED is prevalent among glaucoma patients in Ghana and is associated with age, duration of glaucoma medication, type of preservatives, and number of topical glaucoma medications.