Introduction
Hypertension or HTN, is abnormally high blood pressure and can affect the cardiovascular system, kidneys, cerebrovascular system, and other organs such as the eye. HTN can cause three types of eye damage–optic neuropathy( nerve damage), choroidopathy (build-up of fluid under the retina), and retinopathy (damage to the retina). There is strong emerging evidence that hypertensive retinopathy serves as a predictor of systemic morbidity and mortality due to the target organs affected.
Hypertensive retinopathy is a condition characterised by various retinal vascular symptoms in hypertensive people. Ophthalmoscopy is a part of a standard checkup to detect hypertensive retinopathy in people with high blood pressure.
Hypertensive retinopathy was first identified by Marcus Gunn in the 19th century in many patients, with high blood pressure and kidney diseases.1 In this article, you will learn more about the stages of hypertensive retinopathy, its epidemiology, causes, and characteristics.
What factors cause hypertensive retinopathy
Some factors are important in the increased risk of hypertensive retinopathy.2
- Smoking
It is found that smoking has a strong association with severe or malignant hypertensive retinopathy.
- Genetic factors
The genetic factors associated with hypertensive retinopathy were found to be that deletion of the angiotensin-converting enzyme allele (gene type) is associated with a higher risk of developing hypertensive retinopathy.
- Renal factors
Kidney disorders were observed to be higher in patients with hypertensive retinopathy3
Causes and patterns
Prevalence – some groups of people may have a higher chance of developing HPT retinopathy
- A higher number of Afro-Caribbean people have this as compared to European people
- It is more common in women as compared to men
- The likelihood increases for people aged 40 and over
Prevalence rates varied from 2 to 17 % for various signs of retinopathy due to varying factors.2
Incidence
- The study from Erden et al showed a 66.3% rate of retinopathy in patients with hypertension. The study also laid out how factors such as age and duration of hypertension increase the chances of a person developing the condition
- The Kabedi et al. study showed that 83.6% out of the total hypertensive patients that participated in their research, found chronic kidney disease to be the most significant factor in predicting severe hypertensive retinopathy
- Another study from Del Brutto et al. that investigated which grade (1-3) of retinopathy affected the most people, showed that grade 1 affected 37% of people who took part in the investigation while grade 3 affected 17%
Clinical features of hypertensive retinopathy
HTN retinopathy and its severity are often recognised through the changes in the eye’s anatomy.2,4
Arteriovenous (AV) crossing changes
- Salus’ sign–deflection of retinal vein
- Gunn’s sign–compression of the retinal vein
- Bonnet’s sign– folding of the retinal vein distal to the AV junction
Arterial changes
- Reduction of the arteriovenous ratio to 1:3 from the normal ratio of 2:3
- Alteration of the arteriolar light reflex (light reflex appears as silver and copper wire).
Retinal changes
- Retinal haemorrhages– bleeding from the blood vessels in the retina
- Haemorrhage in the superficial or outer retinal layer (flame-shaped haemorrhage)
- Haemorrhage in the inner retinal layer (dot-blot haemorrhages)
- Exudates on the retina– exudate is a type of drainage that can leak from a damaged blood vessel into surrounding tissues
- Hard exudates–lipid deposits in the retina
- Soft exudates–these are also known as cotton wool spots, which occur due to ischaemia of the nerve fibres.
Macular changes
The macula is a part of the retina that is responsible for most of our vision.
- Macular star formation is caused by the deposition of certain hard material around the macula.6 The deposition prevents the light entering the eye from turning into neural signals and going into the brain and hence the information we receive in the eyes cannot reach the brain and be processed into visual images
Changes in the optic nerve
- Swelling of the optic disc ( part of the eye where the optic nerve forms to send information from the eye to the brain (hypertensive optic neuropathy)
Pathophysiological features
The pathological features are because of the following special characteristics of retinal blood vessels. These are:2
- Presence of a blood-retinal barrier
- Lack of sympathetic nerve supply – responsible for enlarging the iris, allowing more light to enter when needed
- Autoregulation of the blood flow
Stages of hypertensive retinopathy
- Vasoconstricting stage–vasospasm and a narrowing of the retinal arterioles due to local autoregulation mechanisms
- Sclerotic stage–the persistent increase in blood pressure leads to certain changes in the vessel wall
- Thickening and hyperplasia of the vessel wall
- Hyaline degeneration of the arteriolar wall. This stage leads to a more severe form of arteriolar narrowing, changes in the arteriovenous (AV) crossing (i.e., arteriovenous nicking), and widening and enhancement of the light reflex (silver and copper wire)2,4
- Exudative phase
- Disruption of the blood-brain barrier
- Penetration of blood and plasma into the vessel wall disrupts the autoregulation mechanisms
- Damage to the smooth muscles and endothelial cells
- Formation of hard exudate
- Exudation of blood and lipids
These changes are manifested as retinal haemorrhages and cotton wool spots. Swelling of the optic disk may reflect severely elevated blood pressure (i.e., malignant hypertension).5
Classification of hypertensive retinopathy
The classification systems below for hypertensive retinopathy are based on a fundus examination with indirect ophthalmoscopy or a +90 D lens.2
Keith-wagner-barker classification
- Group 1: Slight constriction of retinal arterioles
- Group 2: Group 1 and focal narrowing of retinal arterioles and AV nicking
- Group 3: Group 2 and flame-shaped haemorrhages along with cotton-wool spots and hard exudates
- Group 4: Group 3 and optic disc swelling
Scheie classification
For hypertensive retinopathy
- Stage 0: No visible abnormalities
- Stage 1: Diffuse arteriolar narrowing
- Stage 2: Stage 1 and focal arteriolar constriction
- Stage 3: Stage 2 and retinal haemorrhage
- Stage 4: Stage 3 along with hard exudates, retinal oedema and optic disc swelling
For arteriosclerosis
- Stage 0: Normal
- Stage 1: Widening of the arteriolar light reflex
- Stage 2: Stage 1 and changes in the AV junction
- Stage 3: Copper wiring of the arterioles
- Stage 4: Silver wiring of the arterioles
How is hypertensive retinopathy treated?
Treatment is as per the severity of the condition.2
Mild type
- Control blood pressure through regular monitoring
Moderate type
- A referral to a physician is essential to rule out other associated factors such as diabetes mellitus and to look for cardiovascular abnormalities
- Routine treatment including blood pressure control and monitoring is a must
Severe type
- Requires urgent care and referral as it is most strongly linked to mortality. Other systems like the kidneys, cardiovascular system, and brain should be observed for signs of decline
Complications
Some eye-related complications due to hypertensive retinopathy include:10
- Occlusion (blockage) of the retinal artery
- Occlusion of retinal veins
- Macro-aneurysm (bulging or enlargement) of a retinal arteriole
- Diabetic retinopathy
- Anterior ischaemic ( reduced blood flow) optic neuropathy
- Age-related macular degeneration
- Glaucoma
- Retinal arteriolar emboli (blockage)
- Formation of an epiretinal membrane
- Cystoid macular oedema (swelling caused by fluid)
Healthcare team recommendations
- Coordination between physicians, nurse practitioners, ophthalmologists, nephrologists, and cardiologists is IMPORTANT to ensure early detection and control of hypertension and improve patient outcomes
- Regular follow-up with an ophthalmologist for a complete eye assessment7,8
- Educate patients about the importance of compliance with antihypertensive medication 9
Summary
Hypertensive retinopathy is a clinical condition with characteristic fundoscopic manifestations (arteriolar constriction, AV nicking, hard exudates, and cotton wool spots). Research showed an increase in the incidence of retinopathy is related to the degree of severity and duration of HTN. According to the studies, smoking, genetic factors, as well as renal failure, could play a role in causing hypertensive retinopathy.
The healthcare team is responsible for educating patients about their medications and informing them that they should see their ophthalmologists regularly. Overall, the article provides a comprehensive understanding of hypertensive retinopathy, catering to healthcare professionals and patients, and emphasising the importance of early detection, intervention, and collaborative care.
References
- Schmieder RE. Hypertensive Retinopathy: A Window to Vascular Remodeling in Arterial Hypertension. Hypertension [Internet]. 2008 [cited 2024 Aug 30]; 51(1):43–4. Available from: https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.107.100230.
- Modi P, Arsiwalla T. Hypertensive Retinopathy. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Aug 30]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK525980/.
- Li J, Zhang W, Zhao L, Zhang J, She H, Meng Y, et al. Positive correlation between hypertensive retinopathy and albuminuria in hypertensive adults. BMC Ophthalmology [Internet]. 2023 [cited 2024 Aug 30]; 23(1):66. Available from: https://doi.org/10.1186/s12886-023-02807-6.
- Tsukikawa M, Stacey AW. A Review of Hypertensive Retinopathy and Chorioretinopathy. Clin Optom (Auckl) [Internet]. 2020 [cited 2024 Aug 30]; 12:67–73. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211319/.
- Dziedziak J, Zaleska-Żmijewska A, Szaflik JP, Cudnoch-Jędrzejewska A. Impact of Arterial Hypertension on the Eye: A Review of the Pathogenesis, Diagnostic Methods, and Treatment of Hypertensive Retinopathy. Med Sci Monit [Internet]. 2022 [cited 2024 Aug 30]; 28:e935135-1-e935135-12. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8790937/.
- Patel R, Patel BC, Chauhan S. Neuroretinitis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Aug 30]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK570627/.
- Bhimavarapu U, Chintalapudi N, Battineni G. Automatic Detection and Classification of Hypertensive Retinopathy with Improved Convolution Neural Network and Improved SVM. Bioengineering [Internet]. 2024 [cited 2024 Aug 30]; 11(1):56. Available from: https://www.mdpi.com/2306-5354/11/1/56.
- Triwijoyo BK, Budiharto W, Abdurachman E. The Classification of Hypertensive Retinopathy using Convolutional Neural Network. Procedia Computer Science [Internet]. 2017 [cited 2024 Aug 30]; 116:166–73. Available from: https://linkinghub.elsevier.com/retrieve/pii/S1877050917321166.
- Kosteva K, Kaufman EJ, Kinch A. Case report: The role of hypertension retinopathy graduation in the management of systemic cardiovascular disease. Journal of Family Medicine and Primary Care [Internet]. 2024 [cited 2024 Aug 30]; 13(2):787–91. Available from: https://journals.lww.com/10.4103/jfmpc.jfmpc_1772_22.
- Bhargava M, Ikram MK, Wong TY. How does hypertension affect your eyes? J Hum Hypertens [Internet]. 2012 [cited 2024 Aug 30]; 26(2):71–83. Available from: https://www.nature.com/articles/jhh201137