Vitamin D in ocular and systemic health

Accumulated data supports the argument that vitamin D possesses several biological and molecular actions apart from its role in calcium absorption and facilitation of gene expression. Vitamin D deficiency has been an associated risk factor for cardiovascular disease,metabolic syndrome and ocular complications. The aim of this review is to summarise the most relevant data regarding these associations and to try to clarify whether, and to what extent, oral vitamin D supplementation could be used as a beneficial intervention in such diseases. Vitamin D is produced in skin exposed to sunlight UVB radiation and is then metabolised by the kidney into calciferol, which is an active form. The main function of vitamin D is to promote calcium and phosphorus absorption, and studies have shown that a lack of itplays an important role in ocular conditions, such as age-related macular degeneration and diabetic retinopathy. Recent studies have suggested that vitamin D may protect the diabetic retina; however, other vitamin D-associated conditions (diabetes, hypertension and cardiovascular diseases) may result in secondary ocular manifestations and the potential forsight-threatening complications. The purpose of this review is to describe the current literature on the role of vitamin D in ocular and systemic wellness. However, more research is needed to determine if increasing levels of this vitamin can assist in preventing age-related macular degeneration or diabetic retinopathy. Since vitamin D is a circulating steroid hormone, its receptors are found in almost every cell in the human body, and this suggests that vitamin D might have a very broad role for overall health. However, there is still demand for further research to clarify the clinical use of vitamin D in the prevention and treatment of various chronic diseases

Ocular surface disorder among HIV and AIDS patients using antiretroviral drugs

BACKGROUND : Ocular disorders occur in 50% – 80% of HIV and AIDS patients, and dry eye has been reported as one of the most common anterior segment manifestations in these patients. AIM : The aim of this study was to investigate ocular surface disorders (OSDs) or dry eye in people living with HIV and AIDS on antiretroviral (ARVs) in a controlled setting. SETTING : Mankweng Hospital, ARV Clinic. METHODS : This study included 130 HIV and AIDS participants attending an ART Clinic at Mankweng Hospital and 48 controls. Each participant had an anterior and posterior segment eye examination with a slit lamp and fundus camera, respectively. The dry eye or OSD was investigated with Schirmer’s test and invasive fluorescein tear breakup time (TBUT). RESULTS : The means of the Schirmer’s test and TBUT were 6.7 mm ± 4.0 mm and 6.9 ± 4 seconds in HIV and AIDS participants, while the means in the control group were 13.5 mm ± 3 mm and 14.2 ± 3 s, respectively. The correlations between the severity of dry eye and the level of CD4 cell count were positive and significant. CONCLUSION : There was decreased tear production as measured by the Schirmer’s test and TBUT in our study participants. Statistically significant correlations were found between the severity of dry eye and the level of CD4 cell count. Although the entire pathogenesis of dry eye in HIV and AIDS patients remains unclear, it may be associated with lymphocytic infiltration and destruction of the lacrimal gland.The South African Medical Research Councilhttp://www.avehjournal.orgam202

Update on ocular toxicity of ethambutol

The purpose of this review is to update clinicians on available literature on the ocular toxicity of ethambutol and the type of eye care to be provided to patients treated with these medications. Ethambutol is a commonly used first-line anti-tuberculosis drug. Since its first use in the 1960s, ocular toxicity is described as related to dose and duration, and it is reversible on therapy discontinuation. However, the reversibility of the toxic optic neuropathy remains controversial. The mechanism of ocular toxicity owing to ethambutol is still under investigation. Other than discontinuing the drug, no specific treatment is available for the optic neuropathy caused by ethambutol. Doctors prescribing ethambutol should be aware of the ocular toxicity, and the drug should be used with proper patient education and ophthalmic monitoring.http://www.avehjournal.orgam2016Opthalmolog

Ocular surface disorder among HIV and AIDS patients using antiretroviral drugs

Background: Ocular disorders occur in 50% – 80% of HIV and AIDS patients, and dry eye has been reported as one of the most common anterior segment manifestations in these patients. Aim: The aim of this study was to investigate ocular surface disorders (OSDs) or dry eye in people living with HIV and AIDS on antiretroviral (ARVs) in a controlled setting. Setting: Mankweng Hospital, ARV Clinic. Methods: This study included 130 HIV and AIDS participants attending an ART Clinic at Mankweng Hospital and 48 controls. Each participant had an anterior and posterior segment eye examination with a slit lamp and fundus camera, respectively. The dry eye or OSD was investigated with Schirmer’s test and invasive fluorescein tear breakup time (TBUT). Results: The means of the Schirmer’s test and TBUT were 6.7 mm ± 4.0 mm and 6.9 ± 4 seconds in HIV and AIDS participants, while the means in the control group were 13.5 mm ± 3 mm and 14.2 ± 3 s, respectively. The correlations between the severity of dry eye and the level of CD4 cell count were positive and significant. Conclusion: There was decreased tear production as measured by the Schirmer’s test and TBUT in our study participants. Statistically significant correlations were found between the severity of dry eye and the level of CD4 cell count. Although the entire pathogenesis of dry eye in HIV and AIDS patients remains unclear, it may be associated with lymphocytic infiltration and destruction of the lacrimal gland

Comparison of the amplitude of accommodation determined subjectively and objectively in South African university students

Abstract: Background: Historically, two clinical methods have been used for measuring the amplitude of accommodation, which are the push-up and minus lens methods. However, it has been documented that the push-up method overestimates amplitude of accommodation, while the minus lens method underestimates it. Aim: The purpose of this study was to compare subjective and objective procedures for determining the monocular amplitude of accommodation in young optometry students. Setting: The study was conducted in the optometry clinic at the university. Methods: Amplitude of accommodation was measured on 45 optometry students (17 males and 28 females, whose ages ranged from 21 to 27 years) using the push-up, push-down, minus lens, modified dynamic retinoscopy and Pascal dynamic retinoscopy methods. Data were collected by three different examiners in this study. One examiner measured all the subjective tests, while another examiner measured the modified dynamic retinoscopy. The third examiner measured the Pascal heterodynamic retinoscopy. Results: The highest amplitude of accommodation was obtained using the push-up method (10.23 ± 1.67 D), while the minus lens method gave the lowest subjective finding (8.43 ± 1.68 D). However, the subjective methods generally produced comparable results. Both retinoscopic methods showed the lowest mean amplitude of accommodation of approximately 6.50 ± 1.40 D. However, there was a high correlation between the various methods. Conclusion: The push-up and push-down methods overestimate the true amplitude of accommodation because of the relative magnification, while the minus lens method creates an abnormal viewing environment in which the target is stationary but the stimulus becomes increasingly minified. Subjective amplitude of accommodation is an inadequate measure to assess any true accommodation because it fails to differentiate between passive depth of focus and an active accommodative power change in the eye. Therefore, subjective measurement of the amplitude of accommodation may suggest that accommodation is present when it is not. Further research is needed to further validate dynamic retinoscopy as the optimal or best possible routine clinical method to assess the true amplitude of accommodation

Polyol pathway: A possible mechanism of diabetes complications in the eye

In complex diseases such as diabetes mellitus, the causative agents include various serum factors such as glucose, aldose reductase, oxygen-free radicals, advanced glycation end products, protein kinase-C and growth factors. The polyol pathway is a pathway of glucose metabolism and is regarded as an important element in the pathogenesis of refractive changes, cataract formation and diabetic retinopathy in individuals with diabetes mellitus. The focus of this review is on the role of the polyol pathway in the pathogenesis of diabetic complications in the eye. The first enzyme (aldose reductase) in the polyol pathway reduces glucose to sorbitol. The second enzyme (sorbitol dehydrogenase) converts sorbitol to fructose. The accumulation of sorbitol and fructose in the crystalline lens and retina leads to the generation of oxidative stress. Oxidative stress is the imbalance between levels of reactive oxygen species and the antioxidant defence in a biological system, and it results in tissue damage. How hyperglycaemia leads to oxidative stress is not clear but could be through a combination of increased levels of reactive oxygen species and decreased capacity of the cellular antioxidant system. Oxidative stress causes the development of diabetic complications that are seen clinically

Biochemical changes in diabetic retinopathy triggered by hyperglycaemia: A review

Background: Diabetes mellitus (DM) is now a global health problem which will lead to increasing incidence of macrovascular and microvascular complications that contribute to morbidity, mortality and premature deaths. Diabetic retinopathy (DR) is a serious complication of DM, and its prevalence is increasing worldwide. Diabetes mellitus is one of the fastest growing causes of visual impairment and blindness in the working-age population. Aim: The aim of this paper was to introduce the multiple interconnecting biochemical pathways that have been proposed and tested as key contributors in how the diabetic eye loses vision. Method: An extensive literature search was performed using the Medline database from 1970 to present. The search subjects included diabetes and eye, diabetic retinopathy and diabetic complications in the eye. The search was limited to the literature pertaining to humans and to English language. Preference was given to recent published papers. Results: Results were limited to human participants with publications in English. References of all included papers were also scrutinized to identify additional studies. Studies were selected for inclusion in the review if they met the following criteria: subjects with diabetes, pathophysiology of diabetic retinopathy. Conclusion: Although the biochemical pathways involved in DR have been researched, to date the exact mechanism involved in the onset and progression of the disease is uncertain, which makes therapeutic interventions challenging. The aim of this review is to discuss the possible biochemical pathways and clinical and anatomical changes that occur during the onset and progression of DR that link hyperglycaemia with retinal tissue damage. An understanding of the biochemical and molecular changes may lead to health care practitioners advising patients with DR on events that lead to possible complications of the diseases

Loss of amplitude of accommodation in pre-presbyopic HIV and AIDS patients under treatment with antiretrovirals

Background: The prevalence of HIV and AIDS is causing an enormous public health burden. Its manifestations spare no organ. Ocular complications are mainly attributed to various opportunistic infections which are directly or indirectly caused by immune deficiency. Purpose and aim: The purpose of this study was to determine the effect of HIV and AIDS on subjective amplitude of accommodation of patients under treatment with antiretrovirals and then to compare their results to those of control subjects. Methods: The study took place over a period of 10 months. A quantitative study was carried out on 58 subjects (29 ± 5.5 years) with HIV and AIDS and 35 (28.67 ± 4.6 years) controls of similar age. Amplitude of accommodation was measured using the subjective Royal Air Force push-up method. The influence of CD4+ cell count was also recorded. Results: People with HIV and AIDS had lower mean amplitude of accommodation (5.69 ± 0.88 D) compared to controls (8.53 ± 1.2 D). The decrease in amplitude of accommodation did not show any correlation with the CD4+ cell count. Lower amplitude of accommodation exists in people living with HIV and AIDS when compared with age-related healthy people. Conclusion: The results suggest that patients with HIV and AIDS on antiretroviral drugs (ARVs) have reduced amplitude of accommodation and might experience presbyopia earlier in life than participants without HIV and AIDS. The reduced amplitude of accommodation could be the initial presentation of HIV infection before the systemic manifestation. The possible causes could be the direct neuronal infection by HIV-1, ARVs use, pathological changes of the lens and ciliary muscle or the sensory component of the visual system. It is unknown whether the reduced amplitude of accommodation occurred prior to antiretroviral therapy or represents an ongoing injury to the eye and visual system by the HIV

Is the central corneal thickness of diabetic patients thicker than that of non-diabetics’ eyes?

The purpose of the study was to evaluate central corneal thickness in diabetic patients and to compare the results with controls without diabetes mellitus. Sixty-five diabetic patients (65 eyes) constituted the study group, and 50 eyes were from the healthy control group (50 non-diabetic patients). The study group was subdivided into group 1 (no diabetic retinopathy, n = 35), group 2 (mild to moderate nonproliferative diabetic retinopathy, n = 20), and group 3 (proliferative diabetic retinopathy, n = 10). Central corneal thickness measurements in microns were determined using ultrasound pachymetry. The mean central corneal thickness was significantly greater in the study group (567.14 μm ± 14.63 μm) than in the control group (531.14 μm ± 5 μm). In addition, the mean central corneal thickness was found to be greater in group 3 (577 μm ± 12 μm) than in groups 1 (562 μm ± 13 μm) and 2 (566.86 μm ± 15 μm), but the difference did not reach statistical significance. We found that the mean central corneal thickness for diabetic patients was thicker than that of the healthy controls. Thicker central corneas associated with diabetes mellitus should be taken into consideration when obtaining accurate intraocular pressure measurements in diabetics

Ocular manifestations of HIV and AIDS patients on antiretroviral therapy in a tertiary hospital in South Africa

BACKGROUND : Human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS) causes impairment to the immune system, which then leads to immunocompromised conditions, and allows for opportunistic infection to invade many organs of the human body. Ocular involvement is very common; the various ocular complications may be asymptomatic and they may be the initial manifestations of the underlying diseases. AIM : This study aimed to determine the prevalence and the type of ocular manifestations that occur in HIV and AIDS patients. SETTING : The study was conducted on ART (antiretroviral treatment) clinic patients in the Department of Ophthalmology at the Steve Biko Academic Hospital, Pretoria. METHODS : This descriptive, cross-sectional study was conducted on HIV and AIDS patients referred from the ART clinic for complete ophthalmological evaluation, irrespective of the immune system status and presence or absence of symptoms. All the participants underwent an ophthalmologic evaluation, which included case history and ocular examinations of both anterior and posterior segments. RESULTS : Out of the 177 participants, 72.3% had visual acuity of between 6/3 to 6/18, 10% had poor vision, 7% had lost one eye to ocular complications and 5% were blind. The most common anterior segment manifestations were uveitis and dry eye, whilst HIV-related retinopathy and papilledema were the most prevalent conditions in the posterior segment. Only three participants had third cranial nerve palsy. CONCLUSION : The prevalence of ocular manifestations was significantly higher with lower CD4+ cell counts, which could be regarded as predictors for the occurrence of ocular morbidity in HIV and AIDS patients.The South African Medical Research Councilhttp://www.avehjournal.orgam2022Ophthalmolog