European Journal of Cardiovascular Medicine

Chronic Kidney Disease (CKD) is a burgeoning global health concern, affecting millions worldwide. It leads to a decline in nephron count, progressing to end-stage renal disease (ESRD), necessitating renal replacement therapy for survival [1]. The prevalence of CKD is rising globally, impacting about 850 million people, with one in ten adults affected. Projections suggest that 2040 CKD will rank as the fifth most prevalent cause of years of life lost [2,3]. According to an Indian CKD registry report, among 52 thousand registered CKD patients, 48% had ESRD. Additionally, 16% had CKD with an undetermined cause, while hypertensive nephrosclerosis and glomerulonephritis accounted for 13% and 14% of cases, respectively. Diabetic nephropathy was the most common pathology, affecting 31% of patients [2].

Chronic kidney disease (CKD) manifests systemic effects impacting various body systems. The kidney and eye share significant structural, developmental, physiological, and pathogenic pathways [3,4]. The association between blindness and kidney disease was identified by Richard Bright as early as 1836 [5]. CKD and major eye disorders, including Age-Related Macular Degeneration, Diabetic Retinopathy, hypertensive retinopathy and glaucoma, are linked to age, metabolic factors, and systemic risks such as hypertension, diabetes, and smoking [6]. Additionally, ocular comorbidities can arise from uraemia, anaemia, or the side effects of haemodialysis [7].

Patients with CKD present a diverse range of ocular findings. Edema of the optic disc can occur due to accelerated hypertension [8]. Retinopathy, which includes hypertensive retinopathy and diabetic retinopathy, vascular occlusions such as CRVO, BRVO, HRVO, Maculopathy, and Glaucomatous optic atrophy, are all significant vision-threatening ocular disorders associated with CKD [9]. DR and CKD, blindness owing to proliferative retinopathy or Maculopathy is more prevalent than in normoalbuminuric patients [10].

Deranged metabolism, hypertension, and retinal pigment epithelial dysfunction [11] might all contribute to bullous retinal detachment. Haemodialysis may cause changes in lacrimal secretion and fundus abnormalities such as arteriolar constriction and paleness [12,13].

This study aims to assess the condition of the eyes and associated outcomes in individuals with chronic kidney disease. It also underscores the importance of regular eye examinations to identify potential vision-related issues early and initiate suitable treatment to prevent permanent vision loss.

This hospital-based observational study was conducted from December 2019 to June 2021 on 100 CKD patients at the government medical college in Srikakulam, Andhra Pradesh. Patients included those with CKD, undergoing dialysis, or having had renal transplantation. Exclusion criteria were ocular diseases affecting retinal examination, reversible acute renal failure, ocular ischemic syndrome, and age <14 years. Institutional Ethics Committee approval was obtained, and patients provided written consent in their vernacular language and English.

A comprehensive history covered chief complaints, medical history, and relevant co-morbidities, such as CKD duration, severity, stage, diabetes mellitus duration, hypertension duration, renal disease, coronary arterial disease, cerebrovascular disease, and systemic or ocular medications. Clinical examination comprised a detailed general physical examination, systemic examination including pulse rate, blood pressure, and auscultation of lungs and heart, and local examination of the head, face, and neck. Additionally, all patients underwent a thorough ophthalmological examination.

The ocular examination was comprehensive, encompassing visual acuity assessment with Snellen’s chart (uncorrected and best-corrected), extraocular movements evaluation, and anterior segment examination using slit-lamp biomicroscopy to assess eyelids, conjunctiva, cornea, anterior chamber, iris, pupil, and lens. Fundus examination of both eyes was conducted post-dilation with tropicamide 5% and phenylephrine drops, employing direct ophthalmoscopy, slit-lamp biomicroscopy with a +78-diopter lens, and indirect ophthalmoscopy. Fundus imaging with a Canon Fundus camera was performed when necessary. Data were recorded and analysed using the Chi-Square test and SPSS software version. A probability value (p-value) of <0.05 was deemed statistically significant.

Among the 100 patients included in the study, the largest proportion fell within the age group of 50-59 years, constituting 36% of the total cases, with a mean age of 51.49 years and a standard deviation of 4.9 years. Additionally, the age group of 60-69 years accounted for 21% of the total cases. Of the total, 76 patients were men, while 24 were women. The study group comprised 38 subjects with stage V disease, 22 Stage IV and nine patients - With stage II disease. 15 patients were evenly distributed in groups of stages I, III and 2 in the post-transplant category, of which the maximum patients belonged to the 51-60 age group.

Hypertension was found to be frequently involved in the pathogenesis of CKD, followed by diabetes, and then both hypertension and diabetes. Our study included 100 patients; 98 of those had CKD, and 2 were post-transplant recipients.

Significant Hypertensive Retinopathy were seen in patients. 52% of the participants (104 eyes) showed hypertensive retinopathy changes that were statistically highly significant (p value 0.001). The majority of patients with hypertensive retinopathy have Grade III HR (42%), followed by Grade II HR (29%), Grade I HR (19%), and Grade IV HR (10 %).

Chronic kidney disease is becoming increasingly recognised as a significant global health issue. CKD involves a gradual decline in kidney function and can manifest across all age groups. In a study of 100 patients, the majority fell within the 50-59 age bracket, with an average age of 51.49 years and a standard deviation of 4.9 years, comprising 36% of all cases. Following closely behind were individuals aged 60-69, making up 21% of the cases. Ocular posterior segment findings are important in CKD for visual impairment. These were highly associated with the stage of CKD. In the present study, out of 200 eyes, a total of 144 eyes, constituting 72%, had posterior segment involvement. The most common retinal abnormality seen was hypertensive retinopathy.

The present study results are in accordance with studies done by Sunita et al. [13], Maheshwari et al. [14], Manjula et al. [15], T Mithun et al. [16], Dheeraj et al. [17], RG Mathew et al. [18] study. The present study showed that 72% of patients had a history of hypertension. Out of these, 52 % (104 eyes) had hypertensive retinopathy changes, which are significant statically with a p-value <0.001. Hypertension and CKD have a cause-and-effect relationship. A degrading kidney function with advanced CKD can lead to increased blood pressure, whereas sustained elevations in Blood pressure can deteriorate kidney function.

We then graded the hypertensive retinopathy according to the stage of CKD. We found that Grade 3 HR Is seen in 42% of the patients, making it the most common hypertensive retinopathy in our study. The highest percentage of Grade 3 HR was seen in advanced stages of CKD, 32% in Stage 4 CKD and 36% in Stage 5 CKD. The intensity of retinal microvascular disturbances was identified to be proportional to renal disease progression while comparing hypertensive retinopathy with the stage of CKD, the majority of the patients have Grade III HR (42 %), Grade II HR (29%), followed by Grade I HR (19%) and Grade IV HR (10%).

Out of 104 eyes with HR, Stage 5 CKD patients have the highest number of eyes affected with HR, constituting about 46.15 % (48 eyes), of which the majority were with Grade 3 HR. In Stage 4 CKD patients, 22 eyes (l.15%) were affected with hypertensive retinopathy, of which the most common was Grade 3 HR. In our study, bilateral Grade 4 HR changes with papilledema and macular star were seen in 1 patient with Severe and 4 with ESRD. This shows that advanced stages of CKD are highly affected by hypertensive retinopathy changes. Out of 104 eyes, hypertensive retinopathy changes were seen in 13.46% of Stage 3 CKD patients, 9.6% of Stage 1 CKD patients, and 7.69% of Stage 2 CKD patients. The cause of hypertensive retinopathy changes in CKD is dysregulation of the renin-angiotensin and endothelial systems, which leads to an increase in Endothelin 1 and thickening of the retinal microvascular basement membrane, resulting in retinal arteriolar narrowing and retinal venular dilatation.

These results correlate with most of the other studies. The study by Sunita et al. [14] found hypertensive retinopathy in 52% of the patients, among which 44% had grade three hypertensive retinopathy and the majority affected are with stage 5 CKD. This study by Shoba et al. found hypertensive retinopathy in 46% of the patients, among which 43 eyes had Grade 3 hypertensive retinopathy, and the stage 4 CKD participants were affected in large numbers. In the study by Mithun Thulasidas et al. [15], 53.4% had a history of hypertension, out of which 49.3% had shown hypertensive retinopathy changes. The majority of the patients are with Grade 2 hypertensive retinopathy changes and are seen in stage 2CKD. Our study did not follow Manjula et al. [16], where the most common posterior segment pathology was diabetic retinopathy.

Based on the study's findings, it is evident that chronic kidney disease (CKD) is associated with significant ocular abnormalities, highlighting the importance of visual examination in disease management. The single most common cause of CKD was hypertension. Grade 3 to Grade 4 Hypertensive Retinopathy is vision threatening as the CKD progresses from Stage 1 to End Stage Renal Disease. In the Advanced stages of chronic kidney disease, the highest percentage of eyes affected were with Grade 3 Hypertensive Retinopathy. The eye is a valuable indicator of kidney status, facilitating early detection and intervention to prevent visual loss. Retinopathy, often asymptomatic in its early stages, can progress to severe and vision-threatening conditions as CKD advances. This underscores the need for regular eye screenings and multidisciplinary healthcare for CKD patients. Early referral to ophthalmologists can prevent vision loss by appropriately managing ocular lesions.

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