|Year : 2021 | Volume
| Issue : 3 | Page : 138-143
Retinal findings in chronic kidney disease patients on hemodialysis
Rasha Youssef Hagag1, Shimaa Hassan El-Attar1, Waleed Elrefaey1, Amin E Nawar2, Nashwa M El gharbawy1
1 Department of Internal Medicine, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
|Date of Submission||15-Feb-2021|
|Date of Acceptance||18-May-2021|
|Date of Web Publication||09-Aug-2021|
Dr. Rasha Youssef Hagag
BSc Tanta University, MSc of Internal Medicine Tanta University and MD of Internal Medicine Tanta University; Department of Internal Medicine, Nephrology Unit, Faculty of Medicine, Tanta University, Tanta, 31111
Source of Support: None, Conflict of Interest: None
Background Chronic kidney disease (CKD) is an irreversible condition that leads to progression to end-stage renal disease that requires hemodialysis or kidney transplantation for patient survival and these patients are at risk of developing many complications. In the present study, the retinal findings in CKD patients on hemodialysis are evaluated.
Patients and methods This is a cross-sectional noninterventional study that was carried out on CKD patients on hemodialysis for at least 3 months in the Nephrology Unit, Tanta University, Egypt; 160 eyes of 80 patients were included over 6 months. A complete ophthalmic evaluation was performed. Color fundus and spectral domain optical coherence tomography were performed at presentation.
Results The visual acuity ranged from 6/6 to 6/18 in 80 eyes, which represents 50%, from 6/24 to 6/60 in 62 eyes, which represents 38.75%, and from less than 6/60 to perception of light in 18 eyes, which represents 11.25%. Fundus examination revealed that eight eyes were normal (5%). Hypertensive retinal changes occurred in 82 eyes with variable degrees of retinopathy. Diabetic retinopathy was found in 30 (18.75%) eyes and macular degeneration was detected in 20 (12.5%) eyes. Retinal vasculitis occurred in two (1.25%) eyes, branch retinal vein occlusion was detected in six (3.75%) eyes, glaucomatous optic neuropathy was found in eight (5%) eyes and central retinal artery occlusion occurred in four (2.5%) eyes.
Conclusion The most common visual problems in hemodialysis patients that lead to visual loss are hypertensive and diabetic retinopathy. Hence, it is mandatory to screen fundus changes in CKD to prevent loss of vision.
Keywords: chronic kidney disease, diabetes, hypertension, maculopathy, retinopathy
|How to cite this article:|
Hagag RY, El-Attar SH, Elrefaey W, Nawar AE, El gharbawy NM. Retinal findings in chronic kidney disease patients on hemodialysis. J Egypt Soc Nephrol Transplant 2021;21:138-43
|How to cite this URL:|
Hagag RY, El-Attar SH, Elrefaey W, Nawar AE, El gharbawy NM. Retinal findings in chronic kidney disease patients on hemodialysis. J Egypt Soc Nephrol Transplant [serial online] 2021 [cited 2021 Oct 17];21:138-43. Available from: http://www.jesnt.eg.net/text.asp?2021/21/3/138/323531
| Introduction|| |
Chronic kidney disease (CKD) is defined as structural and functional renal abnormalities that present for more than 3 months with harmful effects on health (according to the KDIGO guidelines); many cases progress to end-stage renal disease (ESRD) ,. The ocular findings in CKD patients undergoing hemodialysis are multiple. Monitoring and follow-up of these patients may have a good impact on their ocular health .
The causes of CKD include glomerular diseases, either primary or secondary to diabetes, systemic autoimmune diseases, and systemic infections; tubulointerstitial diseases, drugs, and autoimmune diseases; vascular causes, atherosclerosis, hypertension, ischemia, and systemic vasculitis; and cystic and congenital diseases, polycystic kidney disease. In ESRD, the patient requires hemodialysis or kidney transplantation for survival. During hemodialysis, multiple metabolic parameters change, such as serum sodium, blood urea, and blood glucose levels. Such changes subsequently lead to osmotic changes in the blood, aqueous, and vitreous humor. In addition, best-corrected visual acuity (BCVA), intraocular pressure (IOP) and the retina can be affected .
There is a wide variation in the ocular problems that may occur in CKD patients: the anterior segment may be affected in the form of lid edema, xanthelasma (increased level of lipids in the serum), conjunctival pallor, and calcification of the cornea and conjunctiva due to hyperactivity of the parathyroid glands. Cataract can also occur due to metabolic changes (calcium–phosphorous dysregulation) and calcium deposition in the lens . Posterior segment may be affected in the form of retinopathy, disc edema, glaucomatous optic atrophy, central retinal artery occlusion and branch retinal vein occlusion . Delay in the diagnosis of such problems can result in blindness .
Hypertensive retinopathy changes are common findings in CKD and may aid in the follow-up of these patients to monitor the status of blood pressure control . Diabetic retinopathy worsens with deterioration of renal function particularly in patients with poor blood pressure control . Macular degeneration and drusen can occur in CKD patients; drusen are tiny yellowish white accumulations of extracellular material under the retinal pigment epithelium . It is very important to examine CKD patients for any possibility of visual impairment and to provide the ideal treatment to prevent irreversible visual loss.
Symptoms of blurring of vision and presence of flashes of light in the field of vision should alert the physician for ophthalmological consultation . Therefore, the present study aimed to assess the retinal findings in CKD patients undergoing hemodialysis.
| Participants and methods|| |
A study was carried out on 160 eyes of 80 patients of CKD. A complete ophthalmic evaluation in the Ophthalmology Department, Tanta University, was performed for all patients. Screening of the patients was performed over a period of 6 months from October 2018 until April 2019.
This was a cross-sectional study.
All procedures in the present study were performed according to the ethical standards of the ethical committee and the 1964 Helsinki declaration and its later amendments.
Informed consent was obtained from all individuals who participated in the study.
Only patients with ESRD secondary to acquired renal diseases were included. Patients were on hemodialysis for at least 3 months or more. The patients underwent hemodialysis sessions of 3–4 h duration each week and the conventional hemodialysis, consisting of a regimen of three sessions per week using a polyethersulfone low-flux hollow fiber with a surface area of 1.6 m2. At the start of the session of the dialysis, the patient was administered one ampoule 1 ml heparin, followed by another one ampoule dissolved in 10 ml saline. Then, we administered 2 ml every 1 h over the 4 h of the dialysis session, with dose modifications according to the bleeding tendency of the patient.
Bicarb capsule 720 g was administered to each patient; there were no major dialysis complications. the most common causes of original kidney disease in our patients were diabetes and hypertension and in one case, it was due to systemic lupus with vasculitis.
Patients with CKD of unknown cause, patients with acute kidney injury and CKD patients with congenital renal diseases were excluded from the study.
All patients were subjected to the following:
Thorough assessment of history and complete clinical examination were performed, with a special focus on blood pressure measurement. Controlled blood pressure in CKD patients was defined as a target blood pressure of less than 140/80 mmHg irrespective of proteinuria according to the 2018 guidelines of The European Society of Cardiology and The European Society of Hypertension .
Grading of the hypertensive retinopathy was performed using the Keith–Wegener classification as follows: grade I: mild diffuse arteriolar narrowing, grade II: focal arteriolar narrowing and arteriovenous crossing changes and moderate-to-severe retinal arteriolar narrowing with prominent arterial light reflex, grade III: areas of retinal hemorrhages, exudates, and cotton wool spots, and grade IV: marked grade III and optic disc edema (papilledema) . The first two grades (grades I and II) are considered to indicate mild to moderate hypertensive retinopathy; grades III and IV are considered to indicate severe hypertensive retinopathy.
Each patient was subjected to a thorough ophthalmic examination including BCVA using the Landolt chart, examination of the anterior segment using a slit lamp, assessment of IOP using applanation tonometry and posterior segment evaluation by both slit-lamp biomicroscopy with a +78 D lens and indirect ophthalmoscopy. Color fundus photography and spectral domain optical coherence tomography (Topcon 3D OCT, Hasunuma-cho, Tokyo, Japan) were performed for all patients at presentation.
The urea reduction ratio (URR) was estimated: URR=(blood urea before dialysis−urea after dialysis)/ureapre dialysis×100; adequate dialysis should be more than 65% .
Statistical data were expressed as percentages or means±SD when appropriate. The χ2 test was used to compare the findings. P values less than 0.05 were considered significant. All statistical results were calculated using the computer program Statistical Package for the Social Science (SPSS, Chicago, Illinois, USA), version 23, for Microsoft Windows.
| Results|| |
There were a total of 80 patients; their ages ranged from 25 to 72 years, mean±SD 54.55±11.72. In terms of the sex distribution, there were 34 (42.5%) male patients and 46 (57.5%) female patients. There were 62 (77.5%) hypertensive patients and 28 (35%) patients with type 2 diabetes mellitus. The visual acuity findings were categorized according to the WHO criteria: 40 (50%) patients presented with good vision with visual acuity (6/6–6/18), impaired vision (6/24–6/60) was detected in 31 (38.75%) patients and the remaining nine (11.25%) patients were legally blind.
In terms of IOP, the mean IOP in the present study was 14 mmHg. Fundus examination revealed wide variations in retinal changes as shown in [Table 1] and in [Figure 1],[Figure 2],[Figure 3]. However, the severity of hypertensive retinopathy was strongly correlated with the degree of blood pressure control as shown in [Table 2].
|Figure 1 A and B: Color fundus of a patient with bilateral severe hypertensive retinopathy changes with scattered retinal hemorrhages and exudates C: OCT of another patient shows severe macular degeneration with foveal thinning.|
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|Figure 2 Color fundus shows NPDR, old laser marks with diabetic maculopathy.|
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|Figure 3 Color fundus of a female patient aged 27 years old with lupus nephritis shows right retinal vasculitis along the lower temporal vascular arcade and left hypertensive retinopathy changes.|
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|Table 2 Illustrating the correlation between blood pressure control and the degree of hypertensive retinopathy|
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Furthermore, it was found that the severity of retinal changes increased as the URR decreased, and the results were statistically significant (P=0.001). The URR in patients with severe retinal changes ranged from 44 to 89%, with mean±SD 57.85±11.08%, while in patients with minimal retinal changes, it ranged from 57 to 92%, with mean±SD 73.34±10.64%; this is shown in [Table 3].
|Table 3 Relation between the severity of retinal changes and urea reduction ratio of all patients|
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| Discussion|| |
In the present study, the retinal findings were more predominant in females. In disagreement with our results, Deva et al.  reported that the retinal findings were more predominant in males. Also, this result is not in agreement with Ravin , Bradford , and Weatherall et al. , who reported that males are at more risk of developing retinal changes.
In terms of BCVA, about 50% of patients have good visual acuity, better than 6/18; however, good visual acuity is not an indicator of the degree of retinal affection as in the severe form of hypertension and diabetes, the macula remains unaffected and this is in agreement with Bourquia et al. , who reported that cataract and refractive errors were the most common causes of loss of vision in patients under chronic hemodialysis.
The mean IOP in our study eyes was 14 mmHg; this is not in agreement with another study carried out by Popa et al.  in which the average IOP of CKD patients was slightly lower than that of the control group (14.9±2 vs. 15.6±1.9 mmHg, respectively, with P=0.07).
Blum et al.  reported that the severity of retinopathy reflects the degree of severity of CKD. In both retinopathy and nephropathy, the basement membrane is markedly thickened with increased leakage. Wong  showed that these pathologic and hemodynamic abnormalities can affect retinal vasculature, with subsequent progressive microvascular damage in addition to hypertension, inflammation, and other processes.
Hypertensive retinopathy was the main retinal finding in the present study, found in 41.25% of the eyes; the severe form occurred in 10% of the eyes. Other studies like Yau et al.  reported findings quite similar to those of our study; they detected severe hypertensive retinopathy changes in 40% of eyes. However, a lower prevalence was reported by Bourquia et al. , who detected hypertensive retinopathy only in 21.3% of cases. The finding that the severity of hypertension predicts the presence and the severity of hypertensive retinopathy was obtained in our study, which correlates well with other studies in the literature such as Wong and McIntosh , who confirmed the role of hypertension in the pathogenesis of CKD and retinopathy. Wong and McIntosh , Duncan et al. , and Wong et al.  showed that in high-risk populations, hypertensive changes can predict an increased incidence of coronary heart disease, cerebral stroke, and death. Wong et al.  and Edwards et al.  also correlated the hypertensive retinopathy changes with declining renal function and this is quite similar to the present study, which detected more severe retinal changes with lower URRs.
According to the present study, diabetic retinopathy was the second most common retinal finding, found in 18.75% of cases. The degree of diabetic retinopathy negatively correlated with the adequacy of dialysis; mild nonproliferative diabetic retinopathy was detected in patients with higher URR, while severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy were detected in patients with lower URR. This correlates strongly with other studies like Leys , Panagoutsos et al. , and Panagoutsos et al. , who documented that the degree of severity of diabetic retinopathy correlates well with the dialysis adequacy. In contrast, the Chronic Renal Insufficiency Cohort study found that most patients presented with diabetic retinopathy; CKD patients with hypertension only had 9% prevalence of retinopathy, while in patients with diabetes alone, the prevalence of retinopathy was 39.5% .
In the present study, diabetic maculopathy was detected in 20 eyes; all types of maculopathy were detected: either focal, diffuse, or cystoid types.
Macular degeneration and drusen were detected in 20 eyes in the present study, and this was positively correlated with the stage of hypertension. Hyman et al.  explained that macular degeneration occurred in renal patients mostly due to age and hypertension, possibly through decreased ability of the choroidal circulation to clear drusen, and this result is in agreement with our study.
Balmforth et al.  and Schlaich et al.  detected chorio-retinal thinning in CKD patients that was not attributed to hypertension, but related to dysfunction of the autonomic nervous system. CKD is a state of increased sympathetic activity that may result in disease progression; thus, increased sympathetic tone affecting the choroidal vasculature could contribute to the thinning of the outer retina and choroid.
Other vascular abnormalities were detected in our study, like branch retinal vein occlusion in six eyes, and this was in agreement with other studies like Wong et al. , who detected cases of retinal vein occlusion in renal patients and this was mostly due to hypertension. Central retinal artery occlusion was diagnosed in four eyes, which was mostly due to hypertension. Also, retinal vasculitis was detected in two eyes with a history of lupus nephritis.
| Conclusion|| |
Hypertensive retinopathy, diabetic retinopathy, diabetic maculopathy, and macular degeneration are the main retinal presentations in patients with CKD on hemodialysis; other findings such as retinal vein occlusion, retinal artery occlusion, retinal vasculitis, and optic neuropathy can occur in variable degrees in such patients. The severity of hypertensive retinopathy was strongly correlated with the degree of blood pressure control, and the severity of diabetic retinopathy was negatively correlated with the adequacy of dialysis. Screening for fundus changes, early recognition, and intervention are mandatory to prevent vision loss in CKD patients.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]