Dialysis, particularly hemodialysis, affects nearly every structure of the eye, from the tear film on the surface to the blood vessels feeding the retina. The informal term “dialysis eyes” captures a cluster of ocular problems that people on chronic dialysis commonly experience: persistent dryness, pressure fluctuations inside the eye, calcium deposits on the cornea, blurred or shifting vision during and after sessions, and a heightened risk of serious vascular events in the retina. These complications arise from the interplay between the uremic state itself, the metabolic turbulence of the dialysis procedure, and the underlying diseases that caused kidney failure in the first place. Understanding what to watch for and how each problem is managed can make a real difference in preserving vision over years of treatment.
Why Dialysis Disrupts the Eye
The fundamental issue is osmotic. During hemodialysis, waste products like urea and creatinine are pulled from the blood into the dialysate, and plasma osmotic pressure drops sharply. But the fluid compartments inside the eye cannot equilibrate at the same speed. Urea concentration in the lens, for example, lags behind the falling blood level, creating a temporary osmotic gradient that draws water into ocular tissues. The lens swells, the anterior chamber shallows, and fluid dynamics inside the eye shift in ways that raise intraocular pressure and distort vision temporarily.
At the same time, hemodialysis removes a large volume of fluid from the body over a few hours, which reduces blood pressure and thins the choroid, the vascular layer behind the retina. This combination of rapid osmotic swings plus aggressive fluid removal is unique to hemodialysis and explains why so many different eye structures are affected in different ways during a single session.
Dry Eye and the Damaged Ocular Surface
Dry eye is one of the most common complaints among dialysis patients, and it goes beyond the mild dryness many people experience from screen time or dry air. Studies consistently find that people with chronic kidney failure have significantly worse tear film stability and more severe dry eye symptoms compared with healthy controls. One study measured tear breakup time and a standardized symptom questionnaire and found that both were significantly worse in dialysis patients, even though basic tear production on a Schirmer test was only modestly lower.
A separate analysis using tear proteomics confirmed that dialysis patients had lower tear volume, shorter breakup times, and higher meibomian gland dysfunction scores than healthy individuals, with every ocular surface parameter showing a statistically significant difference.1Journal of Proteomics. Tear dynamics testing and quantitative proteomics analysis in patients with chronic renal failure The underlying causes are multifactorial. Chronic uremia itself alters tear composition. Fluid restriction limits how much moisture the body can spare. Medications commonly used in kidney disease, such as beta-blockers and diuretics, can suppress tear production. And the dialysis procedure strips fluid from the body, further drying the ocular surface.
One factor that worsens surface disease specifically in dialysis patients is conjunctival calcification, where calcium and phosphate crystals deposit on the white of the eye and sometimes on the cornea. Age, smoking history, corneal thickness, and the presence of conjunctival calcification have all been identified as independent risk factors for dry eye progression in people with end-stage kidney disease.2PubMed Central. The Relationship Between Dry Eye in Adults with Indications for Kidney Transplantation and Influence Factors There is also evidence that hemodialysis may be rougher on the ocular surface than peritoneal dialysis. Impression cytology comparing the two modalities found that hemodialysis patients had significantly more goblet cell loss, squamous metaplasia, and conjunctival keratinization.3Annals of the National Academy of Medical Sciences (India). Analytical Study of Ocular Surface Changes in Patients of Chronic Kidney Disease undergoing Hemodialysis and Peritoneal Dialysis
Corneal and Conjunctival Calcification
Calcium deposits on the eye’s surface are strikingly common in hemodialysis patients. In one study of 29 maintenance hemodialysis patients, about 83% had visible corneal or conjunctival calcification on imaging. More than half had moderate to severe deposits, and the severity of calcification correlated with blood phosphate levels and the calcium-phosphate product.4PubMed Central. Corneal and Coronary Calcification in Maintenance Hemodialysis: The Face Is No Index to the Heart Hyperphosphatemia, the condition of too much phosphate in the blood, was more frequent in patients with moderate to severe deposits.
When calcification spreads across the cornea in a horizontal band pattern, it is called band keratopathy. In mild cases it is just a cosmetic nuisance, a whitish stripe across the cornea. But when it encroaches on the visual axis, it causes glare, irritation, and frank vision loss. Management starts with systemic phosphate control through dietary restriction and phosphate binders. When band keratopathy becomes symptomatic, the first-line local treatment is chelation with topical EDTA, a procedure that chemically dissolves the calcium deposits from the corneal surface. This approach clears the visual axis successfully in the vast majority of cases, with one long-term study reporting that 98% of patients experienced partial or complete symptom relief, and about a third gained meaningful improvement in visual acuity.5PubMed. EDTA chelation for calcific band keratopathy: results and long-term follow-up For denser or irregular deposits, EDTA chelation can be combined with superficial keratectomy or laser treatment to ablate the affected corneal layers.6Clinical Kidney Journal. Band keratopathy and conjunctival calcification in end-stage kidney disease: epidemiology, pathophysiology and clinical management
Intraocular Pressure Swings
Pressure inside the eye can spike during or after a hemodialysis session, a phenomenon that has worried clinicians since the earliest days of dialysis. The mechanism ties back to the osmotic gradient described above. As plasma osmolarity drops rapidly during treatment, aqueous humor production increases, and the swollen lens pushes forward and narrows the drainage angle. These combined effects can push intraocular pressure upward, particularly in patients who already have compromised outflow pathways.7PubMed Central. Effects of Hemodialysis on Intraocular Pressure and Ocular Biological Parameters in Different Angle Structures
Early studies tended to report consistent pressure elevations during hemodialysis.8JAMA Ophthalmology. Effect of Hemodialysis on Intraocular Pressure and Ocular Perfusion Pressure More recent work has given a mixed picture: some patients show increases, others show decreases, and some show no change at all. The direction seems to depend on the individual’s baseline anatomy, particularly the angle of the drainage system and whether there is pre-existing narrow-angle anatomy.9PubMed. Intraocular pressure changes during hemodialysis For most patients, the fluctuations are transient and clinically minor. But for someone with narrow angles or established glaucoma, even a temporary spike can be dangerous.
One case study demonstrated a practical fix: by modifying the dialysis prescription to slow the rate of osmolality change, using conductivity and ultrafiltration profiles along with a colloid solution at the start of the session, a patient with problematic pressure swings became asymptomatic and stopped having measurable pressure variation during treatment.10American Journal of Kidney Diseases. Prevention of intraocular pressure elevations during hemodialysis This suggests that for at-risk individuals, collaboration between the nephrologist and ophthalmologist to adjust dialysis parameters can solve the problem.
Changes in the Choroid and Retina During a Session
The choroid, the dense vascular layer that feeds the outer retina, thins measurably during hemodialysis as the body loses fluid. One study using swept-source imaging found that total choroidal thickness dropped by about 11 micrometers on average after a session, with the reduction occurring in patients both with and without diabetes.11PubMed Central. Evaluation of changes in choroidal thickness and the choroidal vascularity index after hemodialysis in patients with end-stage renal disease by using swept-source optical coherence tomography Another study reported a slightly larger average thinning of about 14 micrometers and found that the degree of thinning correlated with the volume of fluid removed during the session.12Scientific Reports. Optical coherence tomography angiography analysis of changes in the retina and the choroid after haemodialysis In both studies, retinal thickness itself did not change significantly in patients without macular edema.
For patients with diabetic macular edema, however, the fluid removal of hemodialysis can actually shrink the swelling. One study found that maximum macular thickness dropped by about 31 micrometers in eyes with macular edema after a session, and by about 11 micrometers even in diabetic eyes without edema.13Ophthalmologica. Hemodialysis-Induced Alterations in Macular Thickness Measured by Optical Coherence Tomography in Diabetic Patients with End-Stage Renal Disease The reduction was tied to the decrease in plasma osmolality. That sounds beneficial, but the visual acuity did not improve in parallel, likely because the structural damage from chronic diabetes persists regardless of transient fluid shifts.
Retinal Vein Occlusions
End-stage kidney disease substantially raises the risk of retinal vein occlusions, the blockages that cut off blood flow from the retina and can cause sudden vision loss. A large retrospective study in Taiwan found that people with end-stage kidney disease were roughly three times more likely to develop retinal vein occlusion than matched controls, even after adjusting for diabetes, hypertension, and other cardiovascular risk factors.14PubMed Central. Risk of Retinal Vein Occlusion Following End-Stage Renal Disease A separate Taiwanese study confirmed the elevated risk and found that among patients without diabetes, the association was even stronger, with an adjusted hazard ratio of about 2.4.15PubMed Central. End Stage Renal Disease as a Potential Risk Factor for Retinal Vein Occlusion
The implications go beyond vision. The occurrence of a retinal vascular occlusion in a dialysis patient appears to signal increased risk of death and atherosclerotic events like heart attack and stroke.16JAMA Ophthalmology. Risk of Mortality and of Atherosclerotic Events Among Patients Who Underwent Hemodialysis and Subsequently Developed Retinal Vascular Occlusion In other words, a new retinal vein blockage in a dialysis patient is not just an eye problem. It is a red flag for the vascular system as a whole.
Optic Nerve Damage and Papilledema
Dialysis patients face a heightened risk of ischemic damage to the optic nerve, particularly anterior ischemic optic neuropathy. The risk factors are stacked: chronic anemia, accelerated atherosclerosis, and the repeated drops in blood pressure that accompany fluid removal during sessions. Case reports describe bilateral optic nerve damage following hypotensive episodes during dialysis, sometimes leading to permanent blindness.17PubMed Central. Bilateral anterior ischemic optic neuropathy in patients on dialysis: A report of two cases
A different mechanism can also cause optic nerve swelling. Dialysis disequilibrium syndrome, which occurs when urea is cleared from the blood faster than from brain tissue, creates an osmotic gradient that pulls water into the brain. The resulting cerebral edema can raise intracranial pressure enough to cause papilledema, the swelling of the optic disc. At least one documented case involved a patient who developed bilateral optic nerve swelling and decreased vision as part of this syndrome, with caution noted about the risk of permanent visual loss.18PubMed. Papilledema associated with dialysis disequilibrium syndrome Dialysis disequilibrium is most likely in patients starting dialysis for the first time or those with very high pre-treatment urea levels, which is why initial sessions are often deliberately shorter and gentler.
Vitreous Hemorrhage and Bleeding in the Eye
Because hemodialysis requires systemic anticoagulation, usually with heparin, to keep blood from clotting in the dialysis circuit, there has long been concern that this raises the risk of bleeding inside the eye, particularly vitreous hemorrhage in patients with fragile new blood vessels from proliferative diabetic retinopathy. The actual evidence is more reassuring than the worry suggests. One study followed diabetic patients starting hemodialysis and found that vitreous hemorrhage developed in about 23% of eyes in the first year, but this rate was nearly identical to that seen in patients on peritoneal dialysis, which does not require systemic anticoagulation.19PubMed Central. Vitreous hemorrhage in diabetes patients with proliferative diabetic retinopathy undergoing hemodialysis The researchers concluded that heparin used during hemodialysis has little to do with the bleeding. The hemorrhage is driven by the diabetic retinopathy itself and the hemodynamic stresses of renal failure.
Transient Vision Changes
Many dialysis patients report that their vision seems to shift during or shortly after a session. Some describe temporary blurriness; others notice that their glasses prescription seems to change. These transient refractive shifts are real. One study noted that refractive changes occurred in roughly two-thirds of eyes in hemodialysis patients, and that the shift was consistently toward farsightedness. The mechanism makes sense: as the lens swells from osmotic water movement, its curvature and refractive power change. Diabetic patients tend to show the most noticeable visual fluctuations, partly because blood glucose swings during dialysis add another layer of osmotic instability to the lens.20PubMed Central. Effect of hemodialysis on visual acuity, intraocular pressure, and macular thickness in patients with chronic kidney disease
This has a practical implication for prescribing glasses or measuring the eye for surgery. If an eye exam happens during or right after dialysis, the measurements may not reflect the patient’s usual state. Expert guidance recommends scheduling ophthalmologic exams a few hours after a hemodialysis session to get a more accurate baseline.21PubMed Central. The effects of hemodialysis on the eye
Infectious Risks to the Eye
Hemodialysis access, whether a catheter or an arteriovenous graft, creates a portal for bacteria to enter the bloodstream. In rare cases, that bloodstream infection seeds the interior of the eye, causing endogenous endophthalmitis. This is an uncommon but devastating complication that can rapidly destroy vision in the affected eye.22PubMed Central. Endogenous Bacterial Endophthalmitis Complicating Hemodialysis Catheter‐Related Sepsis: A Case Report and Review of the Literature It can develop even from silent or low-grade access infections that cause intermittent bacteremia without obvious systemic symptoms.23PubMed. Enterococcus faecalis endophthalmitis as a metastatic complication of hemodialysis vascular access-related sepsis Any new eye pain, redness, or sudden vision loss in a dialysis patient with an indwelling catheter should be treated as a possible emergency.
Cataract Surgery in Dialysis Patients
Cataracts are common in people on long-term dialysis, partly because of the underlying conditions like diabetes and partly from chronic metabolic stress. Cataract surgery is generally safe, but the outcomes and complication rates differ from the general population. A large population-based study found that people with end-stage kidney disease had roughly a fivefold higher rate of vitreous hemorrhage after cataract surgery and about a threefold higher rate of reoperation for vitreous complications compared with controls.24Scientific Reports. Cataract surgery-related complications in patients with end-stage renal disease- a nationwide population-based study in Taiwan Among non-diabetic patients with kidney failure, the risk of corneal swelling after surgery was also elevated.
Interestingly, visual outcomes after cataract surgery appear to be better in patients who have received a kidney transplant compared with those still on hemodialysis. A comparative study found that the transplant group achieved better postoperative visual acuity and had fewer fundus abnormalities like hemorrhage and macular degeneration.25PubMed Central. Results of cataract surgery in renal transplantation and hemodialysis patients This suggests that restoring kidney function improves the overall ocular environment in ways that support better surgical results.
Practical Management and Screening
Given the number of ways dialysis affects the eyes, regular screening matters. A comprehensive review recommends that ophthalmologic exams be scheduled a few hours after a hemodialysis session to avoid the transient changes in eye pressure, corneal thickness, and refraction that occur during treatment.21PubMed Central. The effects of hemodialysis on the eye This timing yields a more accurate baseline and ensures that decisions about glasses, glaucoma treatment, or surgical planning are based on the patient’s typical state rather than a post-session artifact.
For dry eye, treatment follows the usual stepwise approach: preservative-free artificial tears, lid hygiene for meibomian gland dysfunction, and anti-inflammatory drops if needed. Correcting metabolic factors like phosphate and calcium-phosphate product helps slow conjunctival and corneal calcification. For patients who develop symptomatic intraocular pressure elevations, adjusting the dialysis prescription to slow the rate of osmolality change has been shown to eliminate the problem in individual cases.10American Journal of Kidney Diseases. Prevention of intraocular pressure elevations during hemodialysis
There is also a broader systems-level argument. Because dialysis patients come to the clinic three times a week, the dialysis center itself is uniquely positioned to serve as a hub for screening. Research has suggested that integrating basic eye care into the dialysis setting could lower barriers to screening and improve ophthalmic outcomes for this population.26Investigative Ophthalmology & Visual Science. Eye Care as a Critical Component of Dialysis Patients’ Medical Home Given that many dialysis patients are already managing multiple specialist appointments, having eye screening built into their existing routine rather than requiring a separate trip makes practical sense.
Long-Term Retinal Disease in Dialysis Patients With Diabetes
Diabetes is the leading cause of kidney failure, so a large fraction of people on dialysis carry both conditions simultaneously. The retinal consequences of this overlap are substantial. Advanced imaging in diabetic hemodialysis patients has revealed that every eye examined showed areas of retinal nonperfusion, enlarged foveal avascular zones, and abnormal microvasculature. About half had retinal neovascularization, and a fifth still had diabetic macular edema despite ongoing dialysis.27PubMed Central. The effect of long-term hemodialysis on diabetic retinopathy observed by swept-source optical coherence tomography angiography Critically, these retinal parameters did not change significantly between dialysis sessions, suggesting that the structural damage is chronic and cumulative rather than something that worsens and recovers with each treatment.
For these patients, dialysis is not a substitute for standard diabetic eye care. Anti-VEGF injections, laser photocoagulation, and careful blood sugar management remain the cornerstones of retinopathy treatment regardless of renal replacement therapy. The dialysis process may temporarily reduce macular swelling by pulling fluid, but it does not address the vascular damage driving the disease forward.