Clinical profile of patients with retinal vein occlusion and its correlation with serum homocysteine levels

Abstract

Background

To study the clinical profile of patients diagnosed with retinal vein occlusion (RVO) and its correlation with serum Homocysteine (Hcy) levels.

Methods

This hospital-based cross-sectional study included all patients aged more than 18 years presenting to the Department of Ophthalmology from August 2024 to January 2025. A comprehensive ocular examination was done in all cases. Serum homocysteine levels (Hcy) were estimated in every case. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were compared in patients with and without hyperhomocysteinemia (HHcy) and varying severity of HHcy across diagnoses.

Results

The study included 116 patients diagnosed with RVO. The mean age of patients was 56.4 ± 11.99 years. Most of the patients included in the study were males (60.3%). Central retinal vein occlusion (CRVO) was diagnosed in 32 (27.6%) eyes, and branch retinal vein occlusion (BRVO) in 84 (72.4%) eyes. HHcy was the most common modifiable risk factor in 63.8% of patients. Mild HHcy was seen in 58 (78.4%) and moderate HHcy in 16 (21.6%) patients. The mean Hcy levels in CRVO and BRVO were 19.34 ± 10.97 and 19.45 ± 11.1 µmol/L, respectively. There was a statistically insignificant difference in mean BCVA and CRT according to the presence or absence of HHcy and severity of HHcy across all diagnoses. Increasing age and history of stroke were positively associated with CRVO in univariate analysis.

Conclusion

Elevated serum Hcy is associated with a majority of cases diagnosed with RVO. However, clinical presentation is not affected by the presence or absence of HHcy and its severity.

Background

With a prevalence of approximately 0.7 to 1.6% in the population, retinal vein occlusion (RVO) is the second most common retinal vascular disorder after diabetic retinopathy [1]. Systemic risk factors associated with RVO include diabetes, hypertension, increased body mass index, cardiovascular and cerebrovascular diseases, altered lipid profile, smoking, thyroid disorders, and peptic ulcers. Meanwhile the ocular findings associated with RVO include glaucoma, ocular hypertension, shorter axial length, and localized arteriolar narrowing or arteriovenous nicking [1, 2].

RVO is categorized into two main types: branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). BRVO is the most prevalent type of RVO, with an incidence ranging from 0.44 to 1.6% [2, 3]. BRVO is further classified into two distinct types: major BRVO, involving the occlusion of a major branch retinal vein, and macular BRVO, involving the occlusion of a macular venule [4]. CRVO occurs when the central retinal vein becomes obstructed behind the optic nerve’s lamina cribrosa, typically due to thrombosis. CRVO is divided into two subtypes: non-ischemic (perfused) and ischemic (nonperfused), with the non-ischemic form accounting for about 70% of cases [5]. Individuals with non-ischemic CRVO generally retain better best-corrected visual acuity (BCVA), often better than 20/200.

Elevated blood levels of homocysteine (Hcy) have been closely linked to venous thrombosis and cardiovascular disease, making it a potentially modifiable risk factor for atherosclerosis. Several studies have also indicated that increased Hcy levels may contribute to the risk of CRVO [6–8]. Elevated Hcy can cause direct harm to endothelial cells and stimulate the production of reactive oxygen species (ROS), which induces oxidative stress. This cascade leads to endothelial dysfunction and encourages a prothrombotic environment by increasing platelet aggregation and disrupting coagulation [9, 10]. These processes highlight the role of raised Hcy in causing vascular damage and its possible involvement in the pathogenesis of RVO [11].

Though several studies have linked elevated Hcy levels with the causation of RVO, hardly any studies have compared the clinical findings of patients with RVO with and without raised Hcy levels. The present study aimed to study the clinical profile of patients with RVO and the correlation of serum Hcy levels with presenting visual acuity and central retinal thickness (CRT). We also studied if patients with different grades of hyperhomocysteinemia (HHcy) had varying clinical presentations.

Methods

The present study is a hospital-based cross-sectional study conducted in the Ophthalmology department of a tertiary care referral hospital in Eastern India from August 2024 to January 2025. The clearance of the institutional ethical committee (IEC/IMS.SH/SOA/2024/831) was obtained before starting the study. The study adhered to the basic tenets of the Helsinki Declaration. Written informed consent was obtained from each patient before enrolling them in the study.

All patients aged above 18 years, presenting to the Department of Ophthalmology, and diagnosed with RVO were included in the study. Patients with other retinal pathologies like diabetic retinopathy, anemic retinopathy, leukemic retinopathy, retinal vasculitis, etc., were excluded from the study. Other exclusion criteria included history of ocular trauma, history of retinal surgery, retinal lasers, previous treatment with intravitreal injections, significant media opacity impeding fundus examination, and patients unwilling to participate in the study. Convenience sampling was done for the study. A sample size of 100 was deemed adequate for the study. Finally, 116 patients were included in the study.

After obtaining informed written consent, a detailed history including the patient’s name, age, gender, occupation, address, presenting symptom, progression, and duration of symptoms were recorded. Information regarding systemic ailments like diabetes, hypertension, dyslipidemia, cardiovascular diseases, connective tissue disorders, and cerebrovascular diseases was obtained. Visual acuity was assessed using the Snellen’s chart. Pupillary reactions were checked using the light of an indirect ophthalmoscope. Anterior segment examination was done using a slit lamp. Intraocular pressure was checked using Goldmann’s applanation tonometer. The pupils were dilated using a combination of 0.5% tropicamide and 5% phenylephrine. Dilated fundus examination was done using slit lamp biomicroscopy with a 78-dioptre lens and an indirect ophthalmoscope with 20 dioptre lens. CRT was measured using the 3D macula mode of the spectral domain optical coherence tomography machine (OCT) (3D OCT-1 Topcon Maestro version 8.3, Tokyo). The 3D macula mode has a scan length of 6.0 × 6.0 mm and a resolution of 512 × 128. Fundus fluorescein angiography was done as and when required. The ocular treatment provided in each case was also noted.

Serum Hcy level was estimated in every case. Fasting (overnight fast is preferred) venous blood samples were collected from patients in plain red-top vials and centrifuged at 3500 rpm for 9 min at room temperature. The samples were processed promptly to prevent degradation and minimize interference. Hcy levels were measured using a quantitative enzymatic assay, which employs a two-step enzymatic cycling reaction to convert Hcy into a detectable product. Analysis was done using the Cobas 6000 analyzer (Roche Diagnostics Internation Ltd, Rotkreuz, Switzerland).

HHcy was defined as a serum Hcy level exceeding 15 µmol/L [12]. In the present study, all patients were divided into two groups based on serum Hcy levels: normal homocysteine ≤ 15 µmol/L and elevated homocysteine (Hyperhomocysteinemia) > 15 µmol/L. Patients with HHcy were further divided into three groups: mild (16 to 30 µmol/L), moderate (31 to 100 µmol/L), and severe (> 100 µmol/L) [13].

Statistical analysis

RStudio Desktop’s latest version was used for statistical analysis (Integrated Development for R; RStudio, PBC, Boston, MA). Snellen’s visual equivalents were converted to logarithm of the mean angle of resolution (logMAR) for statistical analysis. Categorical variables were presented as frequency and percentage, whereas continuous variables were presented as mean ± standard deviation (SD). The chi-squared test was used to test the statistical significance of cross-tabulation between categorical variables. An Independent t-test was used to compare the mean ± SD of continuous variables between the two groups. Logistic regression was used to assess the predictors associated with the outcome. P-value < 0.05 was considered statistically significant.

Results

The present study included 116 patients diagnosed with RVO. The mean age of the patients was 56.4 ± 11.99 (95% CI: 54.19 to 58.6) years. Most patients (62.1%) were in the 50 to 70 age group. Ten (8.6%) patients were aged less than 40 years. Most of the patients included in the study were males (60.3%). The mean age of males and females was 57.06 ± 12.30 (95% CI: 54.12 to 59.99) and 55.39 ± 11.56 (95% CI: 51.96 to 58.82) years, respectively (P = 0.467). Right and left eyes were affected in 62 (53.5%) and 54 (46.5%) cases (Table 1). There was no case of bilateral involvement. Among 116 patients, 66 (56.9%) had hypertension, 58 (50%) had dyslipidemia, 30 (25.9%) had diabetes, 6 (5.2%) had a history of cerebrovascular accident (CVA), 6 (5.2%) had connective tissue disorder, and 6 (5.2%) had a history of COVID infection (Table 2). None of the patients enrolled in the study had a history of cardiovascular disease, systemic thromboembolism, and smoking. Two patients had been previously diagnosed with primary open-angle glaucoma and were on anti-glaucoma medications at the time of presentation.

Table 1.

Salient demographic features of the patients enrolled in the study

Variable	Number (%)
Age (years)
21-30	6 (5.2)
31-40	4 (3.4)
41-50	24 (20.7)
51-60	34 (29.3)
61-70	38 (32.8)
71-80	10 (8.6)
Gender
Male	70 (60.3)
Female	46 (39.7)
Laterality
Right eye	62 (53.5%)
Left eye	54 (46.5%)
Diagnosis
CRVO	32 (27.60)
BRVO	84 (72.4)

Table 2.

Systemic illness according to diagnosis

Systemic illness	Total (N = 116)	Diagnosis		P-value
		CRVO (n = 32)	BRVO (n = 84)
Hypertension	66 (56.9%)	16 (50%)	50 (59.5%)	0.355
Diabetes	30 (25.9%)	10 (31.3%)	20 (23.8%)	0.413
Dyslipidemia	58 (50%)	16 (50%)	42 (50%)	1.000
Hyperhomocysteinemia	74 (63.8%)	20 (27%)	54 (73%)	0.858
Cerebrovascular accident (stroke)	6 (5.2%)	4 (12.5%)	2 (2.4%)	0.084
Connective tissue disorder/vasculitis	6 (5.2%)	0 (0%)	6 (7.1%)	0.279
Past H/O COVID	6 (5.2%)	0 (0%)	6 (7.1%)	0.279
Cardiovascular disease	0 (0%)	0 (0%)	0 (0%)	-

CRVO Central retinal vein occlusion, BRVO Branch retinal vein occlusion

CRVO was diagnosed in 32 (27.6%) eyes and BRVO in 84 (72.4%). Non-ischemic and ischemic CRVO were noted in 24 (75%) and 8 (25%) eyes, respectively. Superotemporal BRVO was the most common among BRVO in 46 (54.8%) eyes. Hemi RVO and macular RVO were diagnosed in 6 (7.1%) and 8 (9.5%) eyes, respectively. Diminution of vision was the chief complaint in 98 (84.5%) cases—two (1.7%) patients presented with floaters. Sixteen (13.8%) patients were asymptomatic at presentation, and RVO was diagnosed during routine ocular examination. Ninety-two (79.3%) eyes were phakic, and pseudophakia was noted in 24 (20.7%) eyes. Relative afferent pupillary defect (RAPD), neovascularisation of the iris (NVI), and vitreous hemorrhage were seen in 8 (6.9%), 6 (5.2%), and 8 (6.9%) eyes, respectively. Macular edema was present in 72 (62.1%) eyes (Table 3). CRVO was the diagnosis in all eyes with RAPD and NVI (P < 0.001). OCT assessment for macular edema could not be done in 2 eyes due to dense vitreous hemorrhage. The mean BCVA and CRT were 0.81 ± 0.71 (95% CI: 0.68 to 0.94) logMAR and 360.25 ± 140.39 (95% CI: 334.2 to 386.3) µ, respectively in all RVO eyes. The mean BCVA in CRVO was 1.29 ± 0.82 (95% CI: 1 to 1.59), and in BRVO was 0.63 ± 0.56 (95% CI: 0.5 to 0.75) logMAR (P < 0.001). The mean CRT in CRVO and BRVO was 450.8 ± 156.68 (95% CI: 392.29 to 509.31) and 327.9 ± 119.31 (95% CI: 302.01 to 353.8) µ, respectively (P < 0.001). Among 116 eyes, 56 (48.3%) were treated with anti-vascular endothelial growth factor injections, and 16 (13.8%) received pan-retinal photocoagulation. Intravitreal steroid injection and vitrectomy were performed in 2 (1.7%) of each eye.

Table 3.

Comparison of ocular signs between CRVO and BRVO

Clinical findings	CRVO (N = 32)	BRVO (N = 84)	P-value
RAPD	8 (25%)	0 (0%)	< 0.001
Macular edema	26 (81.25%)	46 (54.8%)	0.009
Vitreous hemorrhage	2 (6.25%)	6 (7.1%)	1.000
NVI	6 (18.75%)	0 (0%)	< 0.001
NVD	4 (12.5%)	0 (0%)	0.006
NVE	0 (0%)	12 (14.3%)	0.055
Tractional RD	0 (0%)	2 (2.4%)	0.934

RAPD Relative afferent pupillary defect, NVI Neovascularisation Iris, NVD Neovascularisation disc, NVE Neovascularisation elsewhere, RD Retinal detachment, CRVO Central retinal vein occlusion, BRVO Branch retinal vein occlusion

Serum Hcy was elevated in 74 (63.8%) patients. Mild HHcy was seen in 58 (78.4%) and moderate HHcy in 16 (21.6%) cases. There were no cases of severe HHcy. Among 74 patients with HHcy, 20 (27%) had CRVO, and 54 (73%) had BRVO. There was a statistically insignificant difference in the proportion of diagnosis according to the presence/absence of HHcy (P = 0.858). The mean serum Hcy level in all RVO patients was 19.42 ± 11.02 (95% CI: 17.4 to 21.45) µmol/L. The mean Hcy levels in CRVO and BRVO were 19.34 ± 10.97 (95% CI: 15.39 to 23.3) and 19.45 ± 11.1 (95% CI: 17.05 to 21.86) µmol/L, respectively. There was a statistically insignificant difference in mean Hcy levels between CRVO and BRVO (P = 0.962). There was also a statistically negligible difference in the mean Hcy levels between ischemic and non-ischemic CRVO (P = 0.192). Maximum patients with HHcy were in the 60 to 70 years age group (22 patients- 57.9%).

The mean BCVA in all RVO patients with and without HHcy was 0.88 ± 0.78 (95% CI: 0.7 to 1.06) and 0.68 ± 0.55 (95% CI: 0.51 to 0.85) logMAR, respectively. The difference in mean BCVA in patients with and without HHcy was not statistically significant across all diagnoses. Similarly, there was a statistically insignificant difference in mean BCVA according to the severity of HHcy across different diagnoses (Table 4). The mean CRT in all RVO patients with and without HHcy was 359.11 ± 136.81 (95% CI: 326.96 to 391.26) and 362.19 ± 147.99 (95% CI: 316.07 to 408.31) µ, respectively. There was a statistically insignificant difference in mean CRT according to HHcy and its severity across different diagnoses (p > 0.05) (Table 5). Variables like HHcy, age, gender, and systemic diseases (diabetes, hypertension, dyslipidemia) were considered for univariate analysis to assess risk factors associated with CRVO and BRVO. Higher age and presence of CVA (stroke) were statistically significantly positively associated with CRVO, according to univariate analysis (P = 0.048). In univariate analysis, lower age and absence of CVA were significantly associated with BRVO (P = 0.048). HHcy and variables with p < 0.05 in univariate analysis were considered for multivariate analysis. None of the variables were found to be significant predictors of both CRVO and BRVO according to multivariate analysis.

Table 4.

Comparison of best-corrected visual acuity according to hyperhomocysteinemia and its severity across different diagnoses

Diagnosis		Best-corrected visual acuity (Logmar), Mean ± SD
	Hyperhomocysteinemia			P-value	Severity of hyperhomocysteinemia			P-value
	Present		Absent		Mild	Moderate	Severe
CRVO	1.42 ± 0.96		1.09 ± 0.5	0.218	1.48 ± 0.97	1.15 ± 0.98	0	0.55
BRVO	0.69 ± 0.6		0.52 ± 0.49	0.187	0.66 ± 0.65	0.79 ± 0.39	0	0.514
ALL RVO	0.88 ± 0.78		0.68 ± 0.55	0.139	0.88 ± 0.83	0.88 ± 0.57	0	0.974

CRVO Central retinal vein occlusion, BRVO Branch retinal vein occlusion, RVO Retinal vein occlusion, Logmar Logarithm of the mean angle of resolution, SD Standard deviation

Table 5.

Comparison of central retinal thickness according to hyperhomocysteinemia and its severity across different diagnoses

Diagnosis		Central retinal thickness (microns), Mean ± SD
	Hyperhomocysteinemia			P-value	Severity of hyperhomocysteinemia			P-value
	Present		Absent		Mild	Moderate	Severe
CRVO	439.89 ± 161.53		467.17 ± 154.63	0.649	406.71 ± 150.27	556 ± 163.97	0	0.104
BRVO	332.19 ± 117.27		320.2 ± 124.54	0.662	333.19 ± 122.91	328.67 ± 99.67	0	0.908
ALL RVO	359.11 ± 136.81		362.19 ± 147.99	0.911	351.57 ± 132.78	385.5 ± 151.65	0	0.385

CRVO Central retinal vein occlusion, BRVO Branch retinal vein occlusion, RVO Retinal vein occlusion, SD Standard deviation

Discussion

RVO is a common vascular disorder of the posterior segment of the eye and can lead to blinding complications if left untreated. The mean age of all RVO patients was 56.4 ± 11.99 years. Our result corroborates with the results of other studies. However, Pinna A et al. [14]. (63.9 ± 14.5 years) and Jonas JB et al. [15]. (63.0 ± 8.9 years) have reported a slightly higher age group. This difference can be attributed to the differences in the demographics of different geographical locations. In the present study, more patients (62.1%) were in the 51–70 age group, similar to the results by Thapa et al. [16] (57.8%) and Singh and Pillai [17] (> 50%). The prevalence of RVO tends to increase with increasing age. This can be due to age-related arteriosclerotic changes, which tend to be more prevalent with increasing age. Elderly patients are also associated with an increasing prevalence of systemic risk factors, which might be responsible for the majority of RVO occurring in the higher age groups.

A male preponderance was observed, with 60.2% of the study population male, similar to the results of most of the studies [14–16]. A female preponderance has been reported in the studies by Yildirim C et al. [18] (54.6%) and Chua B et al. [19] (57%). This variation in gender distribution across studies can be due to differences in the study settings, population demographics, and sampling methods. Factors such as healthcare-seeking behavior, disease prevalence in different regions, and occupational or environmental exposures could also contribute to the observed differences.

Most patients in the present study were diagnosed with BRVO (72.4%) compared to CRVO (27.6%). Similar findings have been reported in the research by Chua B et al. (23.6% CRVO, 76.4% BRVO) [19] and Lee JY et al. (36.4% CRVO, 63.6% BRVO) [20]. A higher prevalence of CRVO has been reported by Arthur D et al. (74.36% CRVO, 25.64% BRVO). BRVO is more common than CRVO in the general population, as it is often associated with localized venous compression at arteriovenous crossings. In contrast, CRVO is more strongly linked to systemic risk factors such as hypertension, diabetes, and hypercoagulability, which may vary among study populations [21].

In the current study, 85.5% of patients presented with a diminution of vision. Diminution of vision was the primary complaint reported in 91.6% and 93.4% of cases, respectively, by Anwar IK et al. [22] and Deb and Paul [23]. This high prevalence of visual impairment as the primary symptom can be attributed to the pathophysiology of RVO. RVO leads to macular edema, retinal ischemia, and retinal hemorrhages, significantly affecting central and peripheral vision. The extent of vision loss depends on the severity and type of occlusion, with CRVO generally causing more profound visual impairment than BRVO. In concordance with this, the mean BCVA in CRVO patients was less than that of BRVO in our study.

Macular edema is the most common cause of vision loss in RVO patients. Macular edema was the most common clinical sign in 62.1% of eyes. A study by Anwar IK et al. [22] noted macular edema as the most common ocular sign in 96.2% of the eyes. Thapa R et al. [16] reported macular edema in only 11.9% of the enrolled eyes. The wide variation in the incidence of macular edema can be due to the varying durations of patient presentation and the type of RVO enrolled in different studies.

Elevated blood Hcy levels have been associated with RVO [11, 12]. Most previous studies have compared Hcy levels in RVO patients with healthy controls. The present study has not included healthy controls. The novelty of the present study is that we have tried to analyze if the presenting clinical features in patients with normal Hcy levels varied from patients with raised Hcy levels. At the same time, we have also analyzed the effect of different severities of HHcy on the clinical presentation. Such an analysis has not been performed in previous studies. In the present study, Hcy levels were elevated in 63.8% of patients. Yildrim et al. [18]. reported Hcy levels to be raised in only 27.3% of all RVO cases. Such a high incidence of HHcy in our study can be explained by the relatively more significant number of patients included in our study. The mean Hcy levels in all patients with RVO was 19.42 ± 11.02 µmol/L. In their research on serum Hcy levels in an Indian cohort, Toshniwal NN et al. [12]. reported mean Hcy levels of 23.80 ± 13.28 µmol/L. The studies by Cahill et al. [24] and Yildrim et al. [18]. have reported mean Hcy levels of 12.9 and 11.7 µmol/L, respectively. In all the above studies, the mean Hcy level in RVO patients was statistically significantly higher than that of normal controls.

In our study, Hcy was mildly elevated in 78.4% of cases and moderately elevated in 21.6%. In a study by Wadani F et al. [8]., Hcy level was moderately (16 to 30) and intermediately (31–100) elevated in 50% each of RVO cases, respectively. The mean Hcy levels in CRVO and BRVO were 19.34 ± 10.97 and 19.45 ± 11.1 µmol/L, respectively. There was no statistically significant difference in the mean Hcy levels between CRVO and BRVO patients in our study. In a similar study, Toshniwal et al. [12] reported mean Hcy levels of 24.27 ± 16.58 and 23.88 ± 11.44 µmol/L in CRVO and BRVO patients, respectively. Like our study, they did not find any statistically significant difference between both groups of patients.

In his study on HHcy in CRVO, Vine AK [11] reported HHcy to be twice as frequent in patients with ischemic CRVO compared to non-ischemic CRVO. The same study also reported HHcy as more prevalent in bilateral CRVO cases. The author concluded that HHcy might be associated with a poor prognosis in CRVO patients. In the present study, we tried to study if patients with HHcy had varying VA and macular status at presentation compared to patients without it. However, the change in mean BCVA was not found to be statistically significant in the presence or absence of HHcy and the severity of HHcy across all diagnoses. Similarly, mean CRT was also not found to be statistically significant in the presence or absence of HHcy and the severity of HHcy across all diagnoses. Also, our study showed that mean Hcy levels in patients with ischemic and non-ischemic CRVO were similar. From our results, it can be concluded that greater severity of HHcy is not associated with a poorer visual acuity at presentation. Also, the clinical characteristics of patients of RVO with or without HHcy are similar.

In the present study, HHcy was the most common modifiable systemic risk factor in most RVO patients. The present study showed a statistically insignificant difference in the proportion of systemic diseases between CRVO and BRVO (P > 0.05), similar to the result by Singh and Pillai [17] and Deb and Paul [23]. In contradiction to these results, Lee JY et al. [20]. reported that the prevalence of diabetes mellitus was significantly higher in patients with CRVO, and hypertension was significantly higher in BRVO patients. In our study, a statistically significant association could not be found for HHcy with the causation of both BRVO and CRVO. HHcy has been reported as an independent risk factor for RVO. Most of the studies discussed above are case-control studies that have included healthy patients as controls and estimated Hcy levels in them. The present study is cross-sectional and has not employed any healthy control group, as previous studies have already reported a positive association of HHcy with RVO. This might be a reason for our study’s results differing from most other studies.

This study has a few limitations. The sample size is relatively small. No control group has been employed. Our study’s lack of a control group limits definitive conclusions about whether HHcy is a causative factor in RVO or merely a coexisting condition. Since this is a cross-sectional study, the effect of treatment and final visual prognosis could not be ascertained. Hence, long-term impact on quality of life cannot be ascertained by this study. Some patients had multiple risk factors in addition in the form of systemic diseases like diabetes, hypertension, and dyslipidemia in addition to raised Hcy levels. In such patients with multiple risk factors, it is hard to conclusively prove that RVO was caused by elevated Hcy levels. We have also not estimated Vitamin B12 levels, which have been estimated in other studies, the addition of which could have increased the value of our study.

Conclusion

RVO can be associated with blinding compliactions if left untreated. Majority of patients affected with RVO are elderly with a male preponderance. BRVO was the most common diagnosis with loss of vision being the most common complaint in majority of the patients. Macular edema was found to be the predominant cause of loss of vision in most of the patients.Serum Hcy level is elevated in a majority of RVO patients. Clinical features of RVO at presentation are similar irrespective of the presence or absence of HHcy and its severity. Our findings suggest that HHcy may not influence disease severity independently. Further large studies are needed to explore the role of HHcy in RVO pathogenesis and its progression.

Abbreviations

RVO

Retinal vein occlusion

BRVO

Branch retinal vein occlusion

CRVO

Central retinal vein occlusion

BCVA

Best-corrected visual acuity

Hcy

Homocysteine

ROS

Reactive oxygen species

CRT

Central retinal thickness

HHcy

Hyperhomocysteinemia

OCT

Optical coherence tomography

logMAR

logarithm of the mean angle of resolution

SD

Standard deviation

CVA

Cerebrovascular accident

RAPD

Relative afferent pupillary defect

NVI

Neovascularisation of the iris

Authors’ contributions

Author contribution statement: DR VLJ: concept, design, the definition of intellectual content, literature search, clinical studies, data acquisition, data analysis, statistical analysis, manuscript preparation; DR PKP: concept, design, the definition of intellectual content, manuscript preparation, manuscript editing, and manuscript review; DR AM: concept, design, the definition of intellectual content, manuscript preparation, manuscript editing, and manuscript review; DR DH: concept, design, the definition of intellectual content, manuscript preparation, manuscript editing, and manuscript review.

Funding

Open access funding provided by Siksha 'O' Anusandhan (Deemed To Be University). Open access funding provided by Siksha'O' Anusandhan (Deemed To Be University). NIL.

Data availability

Data availability: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study adhered to the basic tenets of the Helsinki Declaration. Written informed consent was obtained from each of them before enrolling in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.