Impairment of Colour Vision in Diabetes with No Retinopathy: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SNDREAMS- II, Report 3)

Hotspots: Adherence in home foot temperature monitoring interventions for at-risk feet with diabetes-A narrative review

BACKGROUND

Home foot temperature monitoring (HFTM) is recommended for those at moderate to high ulcer risk. Where a > 2.2°C difference in temperature between feet (hotspot) is detected, it is suggested that individuals (1) notify a healthcare professional (HCP); (2) reduce daily steps by 50%. We assess adherence to this and HFTM upon detecting a recurrent hotspot.

METHODS

PubMed and Google Scholar were searched until 9 June 2023 for English-language peer-reviewed HFTM studies which reported adherence to HFTM, daily step reduction or HCP hotspot notification. The search returned 1030 results excluding duplicates of which 28 were shortlisted and 11 included.

RESULTS

Typical adherence among HFTM study participants for >3 days per week was 61%-93% or >80% of study duration was 55.6%-83.1%. Monitoring foot temperatures >50% of the study duration was associated with decreased ulcer risk (Odds Ratio: 0.50, p < 0.001) in one study (n = 173), but no additional risk reduction was found for >80% adherence. Voluntary dropout was 5.2% (Smart mats); 8.1% (sock sensor) and 4.8%-35.8% (infrared thermometers). Only 16.9%-52.5% of participants notified an HCP upon hotspot detection. Objective evidence of adherence to 50% reduction in daily steps upon hotspot detection was limited to one study where the average step reduction was a pedometer-measured 51.2%.

CONCLUSIONS

Ulcer risk reduction through HFTM is poorly understood given only half of the participants notify HCPs of recurrent hotspots and the number of reducing daily steps is largely unknown. HFTM adherence and dropout are variable and more research is needed to determine factors affecting adherence and those likely to adhere.

Diabetic rats with high levels of endogenous dopamine do not show retinal vascular pathology

Purpose

Limited research exists on the time course of long-term retinal and cerebral deficits in diabetic rodents. Previously, we examined short term (4-8 weeks) deficits in the Goto-Kakizaki (GK) rat model of Type II diabetes. Here, we investigated the long-term (1-8 months) temporal appearance of functional deficits (retinal, cognitive, and motor), retinal vascular pathology, and retinal dopamine levels in the GK rat.

Methods

In GK rats and Wistar controls, retinal neuronal function (electroretinogram), cognitive function (Y-maze), and motor function (rotarod) were measured at 1, 2, 4, 6, and 8 months of age. In addition, we evaluated retinal vascular function (functional hyperemia) and glucose and insulin tolerance. Retinas from rats euthanized at ≥8 months were assessed for vascular pathology. Dopamine and DOPAC levels were measured via HPLC in retinas from rats euthanized at 1, 2, 8, and 12 months.

Results

Goto-Kakizaki rats exhibited significant glucose intolerance beginning at 4 weeks and worsening over time (p < 0.001). GK rats also showed significant delays in flicker and oscillatory potential implicit times (p < 0.05 to p < 0.001) beginning at 1 month. Cognitive deficits were observed beginning at 6 months (p < 0.05), but no motor deficits. GK rats showed no deficits in functional hyperemia and no increase in acellular retinal capillaries. Dopamine levels were twice as high in GK vs. Wistar retinas at 1, 2, 8, and 12 months (p < 0.001).

Conclusion

As shown previously, retinal deficits were detectable prior to cognitive deficits in GK rats. While retinal neuronal function was compromised, retinal vascular pathology was not observed, even at 12+ months. High endogenous levels of dopamine in the GK rat may be acting as an anti-angiogenic and providing protection against vascular pathology.

Retinal neurodegeneration in patients with type 2 diabetes mellitus without diabetic retinopathy

In diabetes mellitus (DM) patients retinal complications were typically considered part of a vascular process. Recent research suggests that retinal degeneration in DM might also be caused by a neuropathy that could precede microvascular alterations. The present work reviews the currently available bibliography about neurodegeneration in patients with type 2 DM (DM2) without diabetic retinopathy (DR). In patients with non-severe, early DM2 without DR and good metabolic control visual function parameters show early abnormalities that precede clinical DR (in which we diagnose with a conventional ophthalmological examination). Using optical coherence tomography (OCT) technology, a reduction in macular and peripapillary thickness has been observed in different studies. Recent researches suggest that systemic complications (especially ischaemia) and a possible microvascular alteration eventually contributes to retinal neurodegeneration, which opens the door to new studies that include new techniques for evaluating the microvascularization of the retinal layers.

The Predictive Role of Thyroid Hormone Levels for Early Diabetic Retinal Changes in Experimental Rat and Human Diabetes

Purpose

In diabetic subjects, early visual functional alterations such as color vision deficiencies (CVDs) are known to precede clinically apparent diabetic retinopathy. Prominent photoreceptor outer segment degeneration and an increase in the number of retinal dual cones (co-expressing S- and M-opsins simultaneously) have been described in diabetic rat models, suggesting a connection with the development of CVDs. As cone opsin expression is controlled by thyroid hormones, we investigated the diabetic retina in association with thyroid hormone alterations.

Methods

In rat models of type 1 and 2 diabetes, dual cones were labeled by immunohistochemistry, and their numbers were analyzed in relation to free triiodothyronine (fT3) and free thyroxine (fT4) levels. Quantification of dual cones was also performed in human postmortem retinas. Additionally, a cross-sectional case–control study was performed where thyroid hormone levels were measured and color vision was assessed with Lanthony desaturated D15 discs.

Results

A higher number of dual cones was detectable in diabetic rats, correlating with fT4 levels. Dual cones were also present in postmortem human retinas, with higher numbers in the three diabetic retinas. As expected, age was strongly associated with CVDs in human patients, and the presence of diabetes also increased the risk. However, the current study failed to detect any effect of thyroid hormones on the development of CVDs.

Conclusions

Our results point toward the involvement of thyroid homeostasis in the opsin expression changes in diabetic rats and human samples. The evaluation of the possible clinical consequences warrants further research.

Malfunction of outer retinal barrier and choroid in the occurrence and progression of diabetic macular edema

Diabetic macular edema (DME) is the most common cause of vision loss in diabetic retinopathy, affecting 1 in 15 patients with diabetes mellitus (DM). The disruption of the inner blood-retina barrier (BRB) has been largely investigated and attributed the primary role in the pathogenesis and progression in DME, but there is increasing evidence regarding the role of outer BRB, separating the RPE from the underlying choriocapillaris, in the occurrence and evolution of DME. The development of novel imaging technologies has led to major improvement in the field of in vivo structural analysis of the macula allowing us to delve deeper into the pathogenesis of DME and expanding our vision regarding this condition. In this review we gathered the results of studies that investigated specific outer BRB optical coherence tomography parameters in patients with DM with the aim to outline the current status of its role in the pathogenesis and progression of DME and identify new research pathways contributing to the advancement of knowledge in the understanding of this condition.

Functional retinal outcomes in patients with prediabetes and type 2 diabetes

PURPOSE

Type 2 diabetes (T2DM) is a leading cause of visual impairment. Its precursor, prediabetes (preDM), is growing in numbers every year. While it is well known that T2DM causes changes in retinal function early in the disease process, it is likely that some of these changes emerge during the preDM stage. This study evaluates retinal function measures in patients with preDM to determine if there are differences in colour vision, contrast sensitivity (CS), and multifocal electroretinogram (mfERG) measures present before T2DM is diagnosed.

METHODS

The L'Anthony desaturated D-15 test, Mars Chart CS test, and mfERG were administered on the right eye of 43 participants; 15 controls (HbA1c ≤ 5.6%), 17 with preDM (HbA1c 5.7%-6.4%), and 11 with T2DM (either physician diagnosed or with untreated HbA1c ≥ 6.5%). HbA1c values were measured at the time of the other tests. Colour vision confusion scores (CVCS) were calculated from the D-15 using the method developed by Torok. Multivariate regression (which controlled for age differences) was used to evaluate the relationship of HbA1c and functional measures. Kruskal-Wallis tests were also used to evaluate differences between groups with post-hoc analysis.

RESULTS

CVCSs were significantly different between the three groups (p = 0.009). There was an association between higher CVCS and higher HbA1c values across all groups as well as specifically within the preDM group when controlling for age (R2  = 0.29, p = 0.01 and R2  = 0.39, p = 0.02 respectively). Multivariate regression of all of the functional tests together and HbA1c found only colour vision remained significant, indicating that the functional examination metrics may provide redundant data, with similar changes in prediabetes where colour vision may be the strongest indicator early in the process.

CONCLUSIONS

Patients with prediabetes have functional changes that can be measured in the retina before the diagnosis of diabetes, with the L'Anthony D-15 colour vision test providing the strongest association with glucose dysregulation in this population. This has important implications for follow up and screening for diabetes within optometric practices. Further studies are needed to follow these patients over time to see how and when these metrics change.

Diabetic Retinopathy: Important Biochemical Alterations and the Main Treatment Strategies

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by impaired glucose homeostasis, insulin resistance and hyperglycemia. Among its serious multisystemic complications is diabetic retinopathy (DR), which develops slowly and often insidiously. This disorder-the most common cause of vision loss in working-age adults-is characterized by functional and morphological changes in the retina. It results from the exacerbation of ischemic and inflammatory conditions prompted by alterations in the blood vessels, such as the development of leukostasis, thickening of the basement membrane, retinal neovascularization and fibrovascular tissue formation at the vitreoretinal interface. The pathogenic alterations are usually triggered at the biochemical level, involving a greater activity in 4 pathways: the polyol pathway, the hexosamine pathway, the formation of advanced glycation end-products and the activation of protein kinase C isoforms. When acting together, these pathways give rise to increased levels of reactive oxygen species and decreased levels of endogenous antioxidant agents, thus generating oxidative stress. All current therapies are aimed at the later stages of DR, and their application implies side effects. One possible strategy for preventing the complications of DM is to counteract the elevated superoxide production stemming from a high level of blood glucose. Accordingly, some treatments are under study for their capacity to reduce vascular leakage and avoid retinal ischemia, retinal neovascularization and macular edema. The present review summarizes the biochemical aspects of DR and the main approaches for treating it.

A critical review: Psychophysical assessments of diabetic retinopathy

Diabetic retinal disease remains a leading cause of vision loss despite currently available screening methods, ocular treatments, and efforts to control metabolic dysfunction. It is now understood that diabetes damages the entire retina and the cellular components of the neurovascular unit. Multiple studies have demonstrated impairment of various aspects of retinal function across the spectrum of retinopathy severity. Here we review these tests, the principles underlying their use, clinical data from multiple publications, the strengths and limitations of the studies, and prospects for their application to understand the pathophysiology of diabetic retinal disease and monitor its response to therapy. We focus on visual acuity, contrast sensitivity, color vision, visual field, and dark adaptation and their use to understand the pathophysiology of diabetic retinopathy and as potential endpoints for clinical trials.

Use of the King-Devick Variable Color Contrast Sensitivity Chart to differentiate stages of age-related macular degeneration

Objective

This study aimed to determine which colour contrast sensitivity differences exist in early to advanced age-related macular degeneration (AMD) and examine the potential utility of the King-Devick Variable Color Contrast Sensitivity Chart in detecting AMD severity.

Methods and analysis

A total of 85 participants (144 total eyes) were recruited from multiple clinical practices and enrolled in the study. The control group consisted of 57 healthy eyes. The non-exudative AMD (NE-AMD) group consisted of 45 eyes. The exudative AMD (E-AMD) group consisted of 42 eyes. In a single study visit, monocular best-corrected visual acuity (BCVA) at 40 cm with 100% black contrast was determined for each eye. Using the BCVA line, the number of letters correctly identified (out of 10) was recorded for various colour presentations (red, green, blue and yellow) and at decreasing contrast levels (100%, 75%, 50% and 25%).

Results

Our results show worse visual performance under various colour contrast settings in E-AMD patients compared with healthy controls and NE-AMD. Colour contrast performance using blue and yellow differentiated more advanced stages of disease in E-AMD from earlier NE-AMD disease. Blue and black colour contrast performance more accurately identified the E-AMD group from healthy controls and the NE-AMD group.

Conclusion

The findings of this study demonstrate that colour contrast, particularly with black, blue and yellow, is impaired in E-AMD suggesting the potential for colour contrast measures to serve as an adjunctive clinical tool in identifying subtle altered visual function as well as the potential for detecting disease severity.

Stereopsis in Early Diabetic Retinopathy

PURPOSE

The present study was undertaken to compare the stereoacuities measured by TNO and Titmus tests, in diabetic patients with early retinopathies and those without diabetes (control group).

METHODS

In this study, 139 participants (43 with diabetes mellitus, and 96 age-matched controls) were recruited from a retina subspecialist clinic in Qazvin, Iran, from September 2016 to March 2017. The stereo-acuities were measured following subjective refraction by Titmus and TNO tests at 40 cm. The patients with diabetes whose retinal exam revealed no background retinopathy or only microaneurysms (very mild diabetic retinopathy) in the worse eye were enrolled into this study.

RESULTS

In the diabetic group, with TNO, the stereoacuity levels in 95.3% of the subjects were in 120, 240, and 480 levels, while in the non-diabetic group, 86.4% of the subjects were in 30, 60, and 120 levels. In the diabetic group, with Titmus, 86.1% of the subjects were in 40, 50, and 60 levels, while in the nondiabetic group 91.7% of the subjects were in 40 levels. The correlation between TNO and Titmus was statistically significant (r = 0.338, P<0.001) for the non-diabetic group, while it was not statistically significant (r = -0.034, P= 0.827) for the diabetic group.

CONCLUSION

In the early stages of diabetic retinopathy, the global pathway of stereopsis is damaged more than the local. The difference in severity of damage to local and global pathways in patients with diabetes indicates that there may be different underlying mechanisms for these two pathways.

Alterations of Retinal Pigment Epithelium-Photoreceptor Complex in Patients with Type 2 Diabetes Mellitus without Diabetic Retinopathy: A Cross-Sectional Study

AIM

A cross-sectional study was performed to examine the alterations of the retinal pigment epithelium- (RPE-) photoreceptor complex layer in type 2 diabetes mellitus (DM) without diabetic retinopathy (DR), using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Patients with type 2 DM without DR and healthy controls without DM were recruited. All participants underwent examinations including SD-OCT. The thickness measurements of the retinal neural layers were calculated after automatic segmentation. An independent-sample t-test was used to compare the means of the thickness of retinal neural layers in patients with DM and healthy controls.

RESULTS

Sixty-seven eyes from 67 patients with DM and 30 eyes from 30 healthy controls were included in this study. No significant differences were found in age (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (P = 0.601), gender (.

CONCLUSION

Lesions in the RPE-photoreceptor complex are present without vascular abnormalities, which may precede the alterations of ganglion cells in patients with type 2 DM.

Role of ω3 polyunsaturated fatty acids in diabetic retinopathy: a morphological and metabolically cross talk among blood retina barriers damage, autoimmunity and chronic inflammation

Vision disorders are one of the most serious complications of diabetes mellitus (DM) affecting the quality of life of patients and eventually cause blindness. The ocular lesions in diabetes mellitus are located mainly in the blood vessels and retina layers. Different retina lesions could be grouped under the umbrella term of diabetic retinopathies (DMRP).

We propose that one of the main causes in the etiopathogenesis of the DMRP consists of a progressive loss of the selective permeability of blood retinal barriers (BRB). The loss of selective permeability of blood retinal barriers will cause a progressive autoimmune process. Prolonged autoimmune injures in the retinal territory will triggers and maintains a low-grade chronic inflammation process, microvascular alterations, glial proliferation and subsequent fibrosis and worse, progressive apoptosis of the photoreceptor neurons.

Patients with long-standing DM disturbances in retinal BRBs suffer of alterations in the enzymatic pathways of polyunsaturated fatty acids (PUFAs), increase release of free radicals and pro-inflammatory molecules and subsequently incremented levels of vascular endothelial growth factor. These facts can produce retinal edema and photoreceptor apoptosis.

Experimental, clinical and epidemiological evidences showing that adequate metabolic and alimentary controls and constant practices of healthy life may avoid, retard or make less severe the appearance of DMRP. Considering the high demand for PUFAs ω3 by photoreceptor complexes of the retina, it seems advisable to take fish oil supplements (2 g per day). The cellular, subcellular and molecular basis of the propositions exposed above is developed in this article.

Synthesizer drawings the most relevant findings of the ultrastructural pathology, as well as the main metabolic pathways of the PUFAs involved in balance and disbalanced conditions are provided.

Early impairments in the retina of rats fed with high fructose/high fat diet are associated with glucose metabolism deregulation but not dyslipidaemia

Way of life changes such as high consumption of processed foods rich in fat and sugar and sedentary lifestyle are associated with the increasing prevalence of metabolic syndrome (MetS) that affects about 35% in the American population. MetS is the main risk factor for diabetes mellitus, which is associated with vascular changes in the retina. However, the early consequences of MetS in the retina are not well described. We therefore aimed at characterizing the early effects of a high fructose and high fat diet (HFHF) on the function and structure of the rat retina, and evaluate the associations with metabolic changes. Brown Norway rats of 6 weeks of age were fed for 8 days, 5 weeks or 13 weeks with HFHF diet, or a standard chow. After only 4 weeks of this diet, rats exhibited a reduction in cone photoreceptor sensitivity to light. Moreover, we observed that MetS significantly exacerbated laser-induced choroidal neovascularization by 72% and 67% 2 weeks and 3 weeks post laser treatment, respectively. These retinal abnormalities were associated with deregulation of glucose metabolism but not lipid metabolism. These data showed retinal modifications in HFHF-induced MetS in the rat, at very early stage of the disease.

Retinal Neurodegeneration as an Early Manifestation of Diabetic Eye Disease and Potential Neuroprotective Therapies

PURPOSE OF REVIEW

Diabetic retinopathy (DR) is a major cause of visual impairment and blindness throughout the world. Microvascular changes have long been regarded central to disease pathogenesis. In recent years, however, retinal neurodegeneration is increasingly being hypothesized to occur prior to the vascular changes classically associated with DR and contribute to disease pathogenesis.

RECENT FINDINGS

There is growing structural and functional evidence from human and animal studies that suggests retinal neurodegeneration to be an early component of DR. Identification of new therapeutic targets is an ongoing area of research with several different molecules undergoing testing in animal models for their neuroprotective properties and for possible use in humans. Retinal neurodegeneration may play a central role in DR pathogenesis. As new therapies are developed, it will be important to develop criteria for clinically defining retinal neurodegeneration. A standardization of the methods for monitoring neurodegeneration along with more sensitive means of detecting preclinical damage is also needed.

Long-Term Anatomic and Functional Outcomes after Macular Hole Surgery

Aim

To evaluate the structural and functional outcomes in patients who underwent macular hole (MH) surgery in the long-term follow-up.

Materials and Methods

Forty-four eyes of 40 patients (28 females and 12 males) were examined. The examination included visual acuity, optical coherence tomography, and colour vision testing. The same evaluation was performed in 30 fellow eyes.

Results

MH closure was obtained in 42 eyes (95.45%). There was no reopening of the initially closed MHs. In long-term postoperative examination, we observed IS/OS junction defects in 28 (63.6%) eyes and ELM defects in 19 (43.2%) eyes. We found that the IS/OS junction defects correlated with the diameter of the MH (p=0.016), whereas ELM defects correlated with both the diameter of the MH (p=0.001) and duration time of the MH (p=0.008). The presence of ELM defects in OCT was the cause of inferior BCVA in long-term observation time (p=0.004). The mean BCVA before the MH surgery was 0.15. It improved significantly both in early (p < 0.001) and long-term postoperative observation (p < 0.005). Generally, the functional outcomes were better in eyes with short-time duration of the MH, when a smaller diameter (<400 μm) of the hole was measured and a V-shaped closure of the MH and the restoration of the ELM line on OCT were present. Pseudoprotanomaly was noted in 13 (35.1%) eyes. In the fellow eye group, mean BCVA was 0.95 (range, 0.6–1.0). In 3 eyes, we detected vitreomacular traction, and in 4 eyes, initial cataract. These conditions, as well as probably early stage of diabetes mellitus, influenced functional outcomes of studied eyes.

Conclusions

The anatomic and functional outcomes after macular surgery are satisfactory and improve with time. After a successful closing of the MH, the restoration of the retina progresses at a slower pace than improvement in visual acuity.

Color vision abnormalities in type II diabetes: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study II report no 2

Purpose:

The purpose of this study is to assess color vision abnormalities in a cohort of subjects with type II diabetes and elucidate associated risk factors.

Methods:

Subjects were recruited from follow-up cohort of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study I. Six hundred and seventy-three eyes of 343 subjects were included from this population-based study. All subjects underwent detailed ophthalmic evaluation, including the Farnsworth-Munsell 100 hue test.

Results:

The prevalence of impaired color vision (ICV) was 43% (CI: 39.2–46.7). Risk factors for ICV were higher heart rate (odds ratio [OR]: 1.043, [1.023–1.064]) and a higher intraocular pressure (IOP) (OR: 1.086, [1.012–1.165]). Subjects with clinically significant macular edema (CSME) had three times higher chance of having ICV. C1, C2, and C3 are the commonly found Early Treatment Diabetic Retinopathy Study (ETDRS) patterns. The moment of inertia method showed that the angle did not reveal any specific pattern of color vision defect. Although the major and minor radii were high in those with ICV, we did not observe polarity. Confusion index was high in subjects with ICV, indicating a severe color vision defect.

Conclusions:

The prevalence of ICV was 43% among subjects with type II diabetes. The most commonly observed patterns were increasing severities of the blue–yellow defect on ETDRS patterns, but no specific pattern was observed at the moment of inertia analysis. The presence of CSME, a higher heart rate, and IOP was significant risk factors for ICV. This functional impairment in color vision could significantly contribute to morbidity among subjects with diabetes.

Occupational exposure to unburnt tobacco and potential risk of toxic optic neuropathy: A cross-sectional study among beedi rollers in selected rural areas of coastal Karnataka, India

BACKGROUND

Beedi also known as poor man's cigarette is manufactured in almost all major states of India. Beedi workers are exposed to various health risks. There is an increased risk of systemic absorption of tobacco through skin and mucous membrane. The optic nerve is susceptible to damage from several toxic substances including tobacco. This group of disorders is known as toxic optic neuropathy (TON). The association of TON with occupational exposure to unburnt tobacco in beedi rollers has not been explored.

OBJECTIVES

Among the beedi rollers in Mangaluru and Bantwal talukas of Dakshina Kannada District, Karnataka, India: to assess the magnitude of potential TON utilizing colour vision and contrast sensitivity as screening tools and to identify the demographic, biological and occupational factors associated with potential TON.

METHODS

A community-based cross-sectional study was conducted from April-Sept 2016 in Mangaluru and Bantwal talukas, of Dakshina Kannada district, Karnataka. Beedi rollers from twelve villages (six from each taluka) were included. In each of the selected villages, the investigators identified beedi collection centres and all the eligible beedi rollers were included in the study till the required number of beedi rollers for that village was achieved. Participants were screened at the study site for visual acuity, colour vision and contrast sensitivity and those with abnormal colour and contrast sensitivity in the presence of good visual acuity were considered to have potential TON.

RESULTS

A total of 377 beedi rollers were approached; of which 365 consented to take part in the study (response rate: 96.81%). Women constituted the majority of the participants (n = 338, 92.6%). Based on the screening criteria, the prevalence of potential TON was 17.5% (n = 64, 95% CI: 13.5-21.9). On multiple logistic regression analysis, duration of beedi rolling (Adj OR: 1.061; 95% CI 1.015-1.109, p = 0.009), advancing age (Adj OR: 1.096; 95% CI 1.058-1.136, p<0.001) and presence of diabetes (Adj OR: 6.315; 95% CI 1.4572-27.376, p = 0.014) were independent correlates of potential TON.

CONCLUSION

In the present study, almost one out of six beedi rollers displayed clinical signs of potential TON. Increased duration of beedi rolling, advancing age and presence of diabetes were the independent correlates of potential TON. However, with this cross-sectional study it is not possible to conclude if these factors play a role individually or collectively or are a serendipitous association, for which large scale analytical studies are required.

Factors associated with impaired color vision without retinopathy amongst people with type 2 diabetes mellitus: a cross-sectional study

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) may develop color vision impairment. This study aimed to determine the prevalence and factors associated with impaired color vision in patients with T2DM but without diabetic retinopathy.

METHODS

Enrolment criteria included multi-ethnic Asian participants, age 21 to 80 years, with known T2DM for a minimum of 2 years. Their diagnoses were affirmed from oral glucose tolerance test results and they were screened for impaired color vision using the Farnsworth D-15 instrument. Demographic characteristics were described and clinical data for the preceding 2 years were analyzed using logistic regression.

RESULTS

Twenty-two percent of 849 eligible participants had impaired color vision with higher involvement of the right eye. Impaired blue-yellow color-vision(Tritanomaly) was the commonest impaired color vision. Participants with impaired color vision were significantly associated with age and lower education; longer duration of T2DM (median 6 years vs 4 years); higher HbA1c level and HDL-Cholesterol in 2nd year; lower mean total cholesterol, mean LDL-Cholesterol and mean triglyceride in 2nd year. They also have poorer vision beyond 6/12 in the affected eye. Logistic regression showed that impaired color vision was associated with older patients (OR=1.04), increased duration of T2DM (OR=1.07); prescription of Tolbutamide (OR=3.79) and lower mean systolic blood pressure (OR=0.98).

CONCLUSION

Almost one in four participants with T2DM had impaired color vision, largely with tritanomaly. Color vision screening may be considered for participants who develop T2DM for 6 years or longer, but this requires further cost-effectiveness evaluation.

Retinal sensitivity in subjects with type 2 diabetes mellitus: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS II, Report No. 4)

AIM

To evaluate retinal sensitivity (RS) in subjects with diabetes in a population-based study and to elucidate associated risk factors for abnormal RS.

METHODS

A subset of 357 subjects from Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study-II was included in this study. All subjects underwent detailed ophthalmic evaluation including microperimetry and spectral domain optical coherence tomography.

RESULTS

The prevalence of abnormal mean retinal sensitivity (MRS) was 89.1%. MRS was significantly reduced in subjects with diabetes but no retinopathy when compared with non-diabetic subjects. MRS was reduced in moderate non-proliferative diabetic retinopathy (DR) and macular oedema (ME) at 8° (p=0.04, p=0.01, respectively) and in ME at 10° (p=0.009) and 12° (p=0.036) compared with no DR. Significant negative correlation was found between MRS and best corrected visual acuity, duration of diabetes, glycosylated haemoglobin and central foveal thickness. Increased retinal thickness remained a significant risk factor (OR, 1.02; p=0.044) for abnormal MRS. Altered inner retinal layers and foveal contour were associated with reduced MRS among subjects with DR and presence of epiretinal membrane, altered foveal contour and altered retinal pigment epithelium were associated with reduced MRS.

CONCLUSIONS

Reduced RS in those subjects with diabetes but no retinopathy suggests the early neuronal damage in type 2 diabetes mellitus.