Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus and remains a leading cause of preventable blindness worldwide.¹ Diabetic retinopathy emerges as the most prevalent and specific microvascular complication.2 This progressive condition represents the leading cause of significant vision loss and preventable blindness among adults in their most productive, working years.3 The risk and progression of diabetic retinopathy increase with duration of diabetes, with almost all type 1 and 60% of type 2 patients developing retinopathy after 20 years, emphasizing duration as a major non-modifiable risk factor.4 While diabetic retinopathy can affect the entire retina, the most frequent cause of vision loss in this disease is the involvement of the macula. This condition, known as diabetic macular edema (DME).5 The diagnosis of CSME, based on stereoscopic slit-lamp biomicroscopy, is defined by the presence of any one of the following criteria: (i) Retinal thickening located at or within 500 µm of the centre of the fovea; (ii) Hard exudates at or within 500 µm of the foveal centre, if they are associated with adjacent retinal thickening; or (iii) A zone of retinal thickening at least one disc area (approximately 1.96 mm²) in size, any part of which is within one disc diameter of the foveal centre.6. Hard exudates are a classic clinical sign of chronic, severe vasogenic retinal edema and are particularly prominent in patients with diabetic macular edema. They present as distinct, waxy, yellow-white deposits within the retina, often forming circinate rings around leaking microaneurysms.7 In the chronically inflamed and high-stress diabetic retina, normal lipid clearance mechanisms are impaired. Combined with ongoing vascular leakage, this leads to extracellular accumulation of lipoproteins, resulting in the formation of clinically visible hard exudates.8 Emerging evidence suggests that dyslipidemia plays an important role in the pathogenesis of these hard exudates. Elevated serum cholesterol and low-density lipoprotein (LDL) levels may exacerbate vascular leakage and deposition of lipids in the retina. Landmark studies such as the Early Treatment Diabetic Retinopathy Study (ETDRS) and the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) have reported a positive correlation between lipid abnormalities and the presence and severity of hard exudates9,10. This study aims to evaluate the association between retinal hard exudates and lipid profile parameters in diabetic retinopathy patients. AIM: To evaluate the association between retinal hard exudates and lipid profile parameters in diabetic retinopathy patients.

A hospital based cross sectional study was conducted on diabetic retinopathy patients during the period from 1 march 2024 to 31 may 2025 in the Department of ophthalmology in a tertiary care centre. INCLUSION CRITERIA: Diabetic retinopathy patients who are 40 years and above with more than 3 years duration of diabetes. EXCLUSION CRITERIA: i. Patients with type 1 diabetes mellitus ii. Patients with hazy media which may impair visualisation of fundus. iii. Non diabetic cases of maculopathy iv. Patients who have undergone any intraocular laser therapy or intravitreal injections in the past. v. Patient with uncontrolled hypertension. vi. Patient already on lipid lowering drugs. vii. Patients not willing to give consent for study. ETDRS classification system was used to classify diabetic retinopathy. Patients were categorized into two groups: Group A included 50 diabetic retinopathy (DR) patients with clinically significant macular edema (CSME), and Group B included 50 DR patients without CSME. Written informed consent was obtained from all participants. Demographic and clinical data, including age, sex, duration of diabetes, hypertension, dyslipidemia, and other systemic illnesses, were recorded using a standardized questionnaire. All study subjects underwent comprehensive ophthalmic evaluation, including BCVA assessment with Snellen’s chart and dilated fundoscopy. Fundus examination was performed with stereoscopic slit-lamp biomicroscopy (+90D Volk lens) and indirect ophthalmoscopy (+20D lens). The BCVA of the worse eye was used for analysis. FBS, PPBS, HbA1C and Lipid profile parameters were measured. A stereoscopic 30 degree color photograph centered on the macula was obtained using SD-OCT (NIDEK RS 330) Grading of severity of hard exudates was done using the Early Treatment Diabetic Retinopathy Study (ETDRS) standard photographs, the severity was categorized as “None” = no HEs present; “Questionable” = questionable HEs present; “Definite” = definite HEs but less than ETDRS standard photograph 3; “Obvious” = HEs greater than or equal to ETDRS standard photograph 3, but less than standard photograph 5; “Moderate” = HEs greater than or equal to standard photograph 5, but less than standard photograph 4; “Severe” = HEs greater than or equal to standard photograph 4; and “cannot grade.

Cross sectional observational study of 50 DR with CSME and 50 DR without CSME patients was undertaken to evaluate the association between retinal hard exudates and lipid profile parameters. The data was analysed using ANOVA statistical test. Association between Hard Exudate Grading and CSME A strong association was observed between hard exudate severity and CSME. Half of the patients without CSME had no hard exudates, whereas all patients with CSME had exudates, with 48.0% showing severe and 22.0% moderate grades. This association was highly significant (χ² = 63.634, p < 0.001). Mean Total Cholesterol Levels Across Different Grades of Hard Exudate Severity Mean total cholesterol increased progressively with worsening hard exudate severity, from 192.60 mg/dl in patients without exudates to 231.33 mg/dl in those with severe exudates. This trend was highly statistically significant (ANOVA, F = 11.814, p < 0.001). Mean HDL Cholesterol Levels Across Different Grades of Hard Exudate Severity Mean HDL cholesterol decreased significantly with increasing hard exudate severity, with the lowest levels observed in severe cases (F = 7.388, p < 0.001). Mean LDL Cholesterol Levels Across Different Grades of Hard Exudate Severity Mean LDL cholesterol increased significantly with worsening hard exudate severity, peaking in severe cases (F = 38.054, p < 0.001). Mean VLDL Cholesterol Levels in Relation to Hard Exudate Severity Mean VLDL cholesterol showed a modest but significant increase with worsening hard exudate severity, highest in severe cases (F = 4.332, p < 0.01) Mean Serum Triglyceride Levels in Relation to Hard Exudate Severity Mean serum triglyceride levels increased significantly with worsening hard exudate severity, with the highest levels in severe cases (F = 4.377, p < 0.01). Table 1 - Association between Hard Exudate Grading and CSME Hard Exudate Grading Group Total Chi square value P value DR with CSME DR without CSME N (%) N (%) N (%) 63.634 <0.001 None 0 (0.0) 25 (50.0) 25 (25.0) Questionable 8 (16.0) 15 (30.0) 23 (23.0) Definite 3 (6.0) 8 (16.0) 11 (11.0) Obvious 4 (8.0) 0 (0.0) 4 (4.0) Moderate 11 (22.0) 2 (4.0) 13 (13.0) Severe 24 (48.0) 0 (0.0) 24 (24.0) Total 50 (100.0) 50 (100.0) 100 (100.0) A strong association was observed between hard exudate severity and CSME. Half of the patients without CSME had no hard exudates, whereas all patients with CSME had exudates, with 48.0% showing severe and 22.0% moderate grades. This association was highly significant (χ² = 63.634, p < 0.001). Table 2- Mean Total Cholesterol Levels Across Different Grades of Hard Exudate Severity Hard Exudate Grading N Mean total cholesterol in mg/dl SD F statistic P value None 25 192.60 21.10 11.814 <0.001 Questionable 23 199.69 21.12 Definite 11 205.18 13.93 Obvious 4 198.75 19.75 Moderate 13 207.08 14.41 Severe 24 231.33 17.69 Mean total cholesterol increased progressively with worsening hard exudate severity, from 192.60 mg/dl in patients without exudates to 231.33 mg/dl in those with severe exudates. This trend was highly statistically significant (ANOVA, F = 11.814, p < 0.001). Table 3 - Mean HDL Cholesterol Levels Across Different Grades of Hard Exudate Severity Hard Exudate Grading N Mean HDL in mg/dl SD F statistic P value None 25 53.44 10.03 7.388 <0.001 Questionable 23 55.09 9.37 Definite 11 54.64 5.44 Obvious 4 45.50 15.42 Moderate 13 47.00 9.73 Severe 24 41.33 7.98 The table shows a statistically significant inverse association between HDL cholesterol levels and the severity of retinal hard exudates. Mean HDL levels were higher in patients with no or questionable hard exudates and progressively declined with increasing exudate severity, reaching the lowest level in the severe group. ANOVA confirmed this inverse relationship to be highly significant (F = 7.388, p < 0.001), indicating that lower HDL levels are associated with more severe hard exudate formation. Table 4 - Mean LDL Cholesterol Levels Across Different Grades of Hard Exudate Severity Hard Exudate Grading N Mean LDL in mg/dl SD F statistic P value None 25 115.00 13.77 38.054 <0.001 Questionable 23 114.57 15.89 Definite 11 121.73 9.11 Obvious 4 115.50 13.10 Moderate 13 133.54 6.49 Severe 24 160.46 15.25 The table demonstrates a statistically significant positive association between LDL cholesterol levels and the severity of retinal hard exudates. Mean LDL levels increased progressively with worsening exudate grade, from the lowest values in patients with no or questionable hard exudates to the highest levels in the severe group. This trend was highly significant on ANOVA (T = 38.054, p < 0.001), indicating that elevated LDL cholesterol is strongly associated with increased severity of hard exudate deposition. Table 5 - Mean VLDL Cholesterol Levels in Relation to Hard Exudate Severity Hard Exudate Grading N Mean VLDL in mg/dl SD F statistic P value None 25 26.20 5.41 4.332 <0.01 Questionable 23 29.39 4.09 Definite 11 28.82 2.27 Obvious 4 29.00 2.94 Moderate 13 28.69 2.28 Severe 24 31.00 1.64 The table shows a statistically significant but modest positive association between VLDL cholesterol levels and the severity of retinal hard exudates. Mean VLDL levels increased with worsening exudate grade, from the lowest values in patients without hard exudates to the highest in the severe group, while intermediate grades showed minimal variation. ANOVA confirmed a significant difference across groups (F = 4.332, p < 0.01), indicating that higher VLDL levels are associated with increased hard exudate severity, though the association is weaker compared to other lipid parameters. Table 6 – Mean Serum Triglyceride Levels in Relation to Hard Exudate Severity Hard Exudate Grading N Mean TG in mg/dl SD F statistic P value None 25 134.64 24.61 4.377 <0.01 Questionable 23 150.26 19.54 Definite 11 145.09 11.33 Obvious 4 151.25 9.70 Moderate 13 146.15 12.06 Severe 24 156.77 8.25 The table demonstrates a statistically significant positive association between serum triglyceride levels and the severity of retinal hard exudates. Mean triglyceride levels increased progressively with worsening exudate grade, from the lowest values in patients without hard exudates to the highest levels in the severe group. This trend was confirmed by ANOVA (F = 4.377, p < 0.01), indicating that elevated triglyceride levels are associated with increased hard exudate severity. DISCUSSION In the present study, most patients were in the 50–70-year age group, consistent with previous reports showing a higher prevalence of diabetic retinopathy (DR) and macular involvement in older individuals. However, no statistically significant association was observed between age and the presence of clinically significant macular edema (CSME), suggesting that age alone may not influence hard exudate formation or macular edema once DR is established. Although a female predominance was noted, particularly among patients with CSME, the association between gender and CSME was not statistically significant, in agreement with earlier studies indicating that gender does not independently affect the development of hard exudates or macular edema in DR. Visual acuity was significantly poorer in patients with CSME compared to those without CSME. Most patients without CSME maintained good visual acuity, whereas the majority of patients with CSME had moderate to severe visual impairment. This finding reinforces the well-established association between macular edema, hard exudate deposition in the macular region, and reduction in central vision, as described in the (ETDRS)9 A strong and statistically significant association was observed between the severity of hard exudates and the presence of CSME. None of the patients with CSME were free of hard exudates, and severe grades of hard exudates were exclusively seen in the CSME group. This finding supports the concept that hard exudates are a clinical marker of chronic vascular leakage and lipid extravasation, which plays a crucial role in the pathogenesis of diabetic macular edema. Analysis of lipid profile parameters revealed a clear relationship between dyslipidemia and the severity of retinal hard exudates. Mean total cholesterol and LDL cholesterol levels showed a progressive and statistically significant increase with worsening grades of hard exudates. LDL cholesterol, in particular, demonstrated the strongest association, suggesting its major role in lipid leakage and retinal deposition. These findings are in agreement with previous studies by Chew et al. and Klein et al.9 which reported higher serum cholesterol levels in patients with prominent retinal hard exudates. An inverse relationship was observed between HDL cholesterol levels and hard exudate severity. Patients with severe hard exudates had significantly lower HDL levels. HDL is known to exert protective effects by promoting reverse cholesterol transport and reducing endothelial dysfunction. Reduced HDL levels may therefore contribute to increased vascular permeability and lipid deposition within the retina. Serum triglyceride and VLDL levels also showed a statistically significant positive association with hard exudate severity, although the strength of association was less pronounced compared to LDL cholesterol. Elevated triglyceride-rich lipoproteins may contribute to endothelial dysfunction and increased capillary leakage, further aggravating retinal lipid deposition. A similar study by Idiculla J et al. on type II diabetics who presented with hard exudates in the retina showed a significant correlation between dyslipidemia, total cholesterol levels, LDL levels, and hard exudate formation. No significant association was noted with HDL, and triglyceride levels showed a trend toward significance.11 Overall, the findings of this study support the hypothesis that dyslipidemia plays a significant role in the development and progression of retinal hard exudates in diabetic retinopathy. As this was a cross-sectional study, a causal relationship cannot be definitively established; however, the strong associations observed suggest that lipid abnormalities may act as important modifiable risk factors. LIMITATIONS: The cross-sectional design of our study limits the ability to establish a causal relationship between dyslipidemia and the presence of retinal hard exudates. Additionally, being a single-center study with a moderate sample size, the findings may not be generalizable to the broader diabetic population.

This cross-sectional study identifies a significant association between retinal hard exudates and serum lipid abnormalities in patients with diabetic retinopathy. Greater severity of hard exudates was strongly associated with elevated total cholesterol, LDL cholesterol, triglycerides, and VLDL levels, along with reduced HDL cholesterol. Severe hard exudates were also closely associated with the presence of clinically significant macular edema and poorer visual acuity. These findings underscore the importance of comprehensive systemic evaluation, including lipid profile assessment, in patients with diabetic retinopathy. Early identification and effective management of dyslipidemia may help reduce retinal lipid accumulation, slow the progression of hard exudates, and potentially lower the risk of macular edema and vision loss. Further longitudinal studies are warranted to clarify causal relationships and to assess the impact of lipid-lowering therapy on retinal outcomes. AUTHORS CONTRIBUTION STATEMENT Dr Aiswarya J S MBBS Conceptualized and designed the study, conducted patient recruitment and clinical evaluation, performed data analysis and interpretation, and drafted the manuscript. Dr Midhun S R MBBS, DNB Contributed in clinical data collection, data validation, and literature review, and contributed to manuscript revision. Dr Revathy G S MBBS,DNB Supervised the study, provided methodological guidance, and critically reviewed and approved the final manuscript. Dr Kajal Seema S MBBS, MS, DO, DNB Final approval of the version to be published CONFLICTS OF INTEREST The authors declare no conflicts of interests SOURCE OF FUNDING No external funding was received. ACKNOWLEDGMENT The authors deeply acknowledge Dr Kajal Seema S, Professor and HOD, all the faculties and staff of the department of Ophthalmology, Sree Uthradom Thirunal Academy of Medical Sciences, for providing facilities for the study and thank the patients for their participation.

1.Wild S, Roglic G, Green A, Sicree R, King H. Global prevalence of diabetes: estimates for the year 2000 and projections for 2030. Diabetes Care. 2004;27(5):1047–1053. 2.Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376(9735):124–136. 3.Teo ZL, Tham YC, Yu M, Chee ML, Rim TH, Cheung N, et al. Global prevalence of diabetic retinopathy and projection of burden through 2045: a systematic review and meta-analysis. Ophthalmology. 2021;128(11):1580–1591. 4.American Diabetes Association Professional Practice Committee. Retinopathy, neuropathy, and foot care: Standards of Medical Care in Diabetes—2022. Diabetes Care. 2022;45(Suppl 1):S185–S194. 5.Ciulla TA, Amador AG, Zinman B. Diabetic retinopathy and diabetic macular edema: pathophysiology, screening, and novel therapies. Diabetes Care. 2003;26(9):2653–2664. 6.Browning DJ, Altaweel MM, Bressler NM, Bressler SB, Scott IU. Diabetic macular edema: what is focal and what is diffuse? Am J Ophthalmol. 2008;146(5):649–655.e6. 7.Das A, McGuire PG, Rangasamy S. Diabetic macular edema: pathophysiology and novel therapeutic targets. Ophthalmology. 2015;122(7):1375–1394. 8.Kaur C, Foulds WS, Ling EA. Blood–retinal barrier in hypoxic ischaemic conditions: basic concepts, clinical features and management. Prog Retin Eye Res. 2008;27(6):622–647. 9.Chew EY, Klein ML, Ferris FL III, Remaley NA, Murphy RP, Chantry K, et al. Association of elevated serum lipids with retinal hard exudate in diabetic retinopathy. Early Treatment Diabetic Retinopathy Study Report 22. Arch Ophthalmol. 1996;114:1079–1084. 10.Klein BEK, Moss SE, Klein R, Surawicz TS. The Wisconsin Epidemiologic Study of Diabetic Retinopathy. XIII. Relationship of serum cholesterol to retinopathy and hard exudate. Ophthalmology. 1991;98:1261–1265. 11.Idiculla J, Nithyanandam S, Joseph M, Mohan VA, Vasu U, Sadiq M. Serum lipids and diabetic retinopathy: a cross-sectional study. Indian J Endocrinol Metab. 2012;16(Suppl 2):S492–S494.