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Do Hormone Conditions Cause Eye Problems?


The various organs that produce hormones in the body
The various organs that produce hormones in the body

Endocrine (hormone) diseases make up a significant percentage of the chronic diseases that veterinarians diagnose and manage. Many of these endocrinopathies (hormone diseases) have serious ocular (eye) signs that may interfere with the quality of life of an animal.


Hormonal diseases are prevalent diseases that typically affect multiple organs, and the eye and its surrounding tissues are often involved in endocrine disorders. Some of the conditions, e.g. diabetes and thyroid gland dysfunction, can cause serious eye pathology and even blindness.

The various methos by which organs are stimulated to release hormones
The various methos by which organs are stimulated to release hormones

A clear understanding of the pathogenesis of these endocrinopathies and their ocular manifestations enhances preventive, therapeutic and management measures to reduce the incidence of sight-threatening complications. Some of the common hormone diseases that are expressed through the eyes are listed below.


Diabetes Mellitus

 

Diabetes mellitus is a fairly common endocrine (hormone) disorder in dogs and cats. It is commonly seen in middle-aged to older pets, characterized by a relative or absolute insulin deficiency. Diabetes mellitus causes an inability to transport glucose from the bloodstream into cells leading to elevated glucose concentrations, and hyperglycaemia. Glucose then gets excreted in the urine, leading to polyuria and polydipsia. Besides, glucose metabolism gets impaired leading to a deterioration in the general condition of the animal and death if untreated. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Cataract

    1. Lens-induced uveitis

  2. Peripheral neuropathy

    1. Decreased corneal sensation

    2. Ulceration

    3. Impaired corneal healing

    4. Keratoconjunctivitis sicca (KCS)

    5. Facial nerve palsy

    6. Horner’ssyndrome

  3. Hyperlipidemia

    1. Lipemia retinalis

    2. Lipemic aqueous humour

  4. Retinopathy

  5. Systemic hypertension

    1. Retinal haemorrhage

    2. Retinal detachment

    3. Hyphema


Hyperadrenocorticism (HAC, Cushing’s disease)

 

In dogs, Cushing's disease (hyperadrenocorticism) is a health condition that occurs when the adrenal glands in the animal's body overproduce cortisol (cortisone).



Excess cortisol risks the dog to life-threatening conditions and illnesses, ranging from kidney damage to diabetes. In the dog, Cushing’s disease is caused by a benign or malignant tumour in the pituitary gland, a pea-sized gland located at the base of the brain or in rare cases the tumour could be located in the adrenal glands, located on top of the kidneys. Iatrogenic Cushing's syndrome is caused by excessive cortisol production stemming from the prolonged use of steroids. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Systemic hypertension

    1. Retinal haemorrhage

    2. Retinal detachment

    3. Hyphema

  2. Hyperlipidemia

    1. Corneal lipid deposits

    2. Lipemia retinalis

    3. Lipemic aqueous humour

  3. Pituitary macroadenoma

    1. Blindness

    2. Cranial nerve dysfunction

    3. Oculomotor palsy

    4. Ptosis

  4. Immunosuppression

    1. Opportunistic infections

    2. Keratitis

    3. Uveitis

    4. Endophthalmitis

  5. Ectopic calcification

    1. Band keratopathy

    2. Ulceration

    3. Impaired corneal healing

  6. Facial paralysis

    1. Exposure keratitis

  7. Exophthalmos

    1. Exposure keratitis

  8. SARD


Hypoadrenocorticism (Addison’sdisease)

 

Hypoadrenocorticism (Addison disease) is an uncommon condition in dogs and even more rare in cats. Hypoadrenocorticism is most often caused by immune-mediated destruction of the adrenal glands resulting in decreased mineralocorticoid and glucocorticoid production. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Hypercalcemia

    1. Metastatic calcification

      1. Band keratopathy

      2. Deposits in the conjunctiva and elsewhere


Pheochromocytoma

 

Pheochromocytoma is a special type of endocrine tumour that arises from the adrenal gland. The cells that give rise to this specific tumour secrete certain hormones called catecholamines that regulate various functions within the body. Tumours typically occur in middle-aged to older dogs. Pheochromocytomas arise from the adrenal medullary chromaffin cells that normally synthesize and secrete the catecholamines epinephrine and norepinephrine. These tumours have been identified more often in dogs than in cats, usually affect only one gland, and tend to occur in older animals. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Mydriasis

  2. Systemic hypertension

    1. Retinal haemorrhage

    2. Retinal detachment

    3. Hyphema


Acromegaly

 

Acromegaly is an endocrine disease that leads to elevated production and secretion of growth hormone (GH). It occurs in adult and aged cats and is usually associated with neoplasms, such as functional pituitary macroadenoma of somatotropic cells. In dogs, it is usually related to an increase in serum progesterone that induces the production of growth hormones by the mammary glands. The main clinical signs are related to insulin resistance and the anabolic effect induced by the growth hormone: polyuria, polydipsia, polyphagia, increased tissue growth, weight gain, prognathism, and other changes. The main characteristic findings of canine acromegaly are a visible increase in soft tissue mass, prominent skin folds, abdominal enlargement, and/or radiographic evidence of an increase in soft tissue mass in the orolingual, oropharyngeal, and orolaryngeal regions. Acromegalic dogs almost invariably show some degree of respiratory stridor. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Papilledema: swelling of the optic nerve, which connects the eye and brain. This swelling is a reaction to a buildup of pressure in or around the brain that may be due to either a brain tumour or haemorrhage.

  2. Systemic hypertension

    1. Retinal haemorrhage

    2. Retinal detachment

    3. Hyphema

  3. Diabetes(above)


Pituitary dwarfism - Growth hormone deficiency (GHD)

 

Growth hormone deficiency (GHD), also known as dwarfism or pituitary dwarfism, is a condition caused by insufficient amounts of growth hormone in the body. Panhypopituitarism in young dogs usually results from failure of the pars distalis of the pituitary to develop during gestation. This leads to a deficiency of all the pituitary trophic hormones. Some cases are caused by benign craniopharyngiomas, which lead to subnormal levels of growth hormone. The ocular (eye) conditions that are indirectly caused by this hormone are due to:-

  1. Hypothyroidism (below)


Hypothyroidism

 

The thyroid gland is one of the most important glands in the body. It is located in the neck near the trachea or windpipe and has two lobes, one on each side of the trachea. The pituitary gland controls the thyroid gland, located at the base of the brain. The thyroid gland regulates the body's metabolic rate. If the thyroid is overactive (hyperthyroidism), the body's metabolism is elevated. If it is underactive (hypothyroidism), the metabolism slows down. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Hyperlipidemia

    1. Corneal lipid deposits

    2. Lipemic aqueous humour

    3. Lipemiaretinalis

  2. Keratoconjunctivitis sicca (KCS)

  3. Peripheral neuropathy

    1. Facial paralysis

    2. Exposure keratitis

    3. Horner’s syndrome

    4. Keratoconjunctivitis sicca (KCS)


Hyperthyroidism

 

Hyperthyroidism is the condition caused when the thyroid gland produces an excess amount of hormones. Hyperthyroidism is a very serious but relatively rare condition in dogs and typically results from thyroid carcinoma, (an aggressive and fast-growing cancer of the thyroid). The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Systemic hypertension

    1. —Retinal haemorrhage

    2. —Retinal detachment

    3. —Hyphema

  2. Hypercalcemia

    1. Metastatic calcification

    2. Band keratopathy

    3. Deposits in the conjunctiva and elsewhere


Hypocalcemia

 

Hypocalcaemia develops when there is a reduction in the bone mobilization of calcium, enhanced skeletal calcium accretion, increased urinary losses of calcium, reduced gastrointestinal absorption of calcium, calcium is translocated intracellularly, or as a result of a combination of these mechanisms. Hypocalcemia is a relatively common abnormality observed in pets with a prevalence of 31% in dogs and 27% in cats. The ocular (eye) conditions that are indirectly caused by this disease include:-

  1. Cataracts

  2. Prolapsed nictitans

  3. Papilloedema

  4. Optic neuritis

  5. Conjunctivitis

  6. Keratitis

  7. Strabismus

  8. Nystagmus

  9. Anisocoria


Hypercalcemia

 

Hypercalcemia is defined as either an elevation of total serum calcium (tCa) or ionized calcium (iCa) above physiologically normal levels. In dogs, tCa above 12.0 mg/dl or iCa above 1.5 mmol/L qualifies as hypercalcemia, while in cats, tCa above 11.0 mg/dl or iCa above 1.4 mmol/L qualifies as hypercalcemia. Elevated iCa can affect multiple organs, resulting in altered cell membrane permeability and subsequent disturbances in biological functions of the nervous, gastrointestinal, cardiac, and renal systems.

  1. Metastatic calcification

    1. Band keratopathy

    2. Deposits in the conjunctiva and elsewhere.


References

 

Plummer, C. E., Specht, A., & Gelatt, K. N. (2007). Ocular manifestations of endocrine disease. Compendium.


Mounirou, B. A. M. (2021). Ocular Manifestations of Endocrine Diseases. Saudi J Med Pharm Sci, 7(11), 584-590.


Anoop, S., Philip, L. M., Ramankutty, S., & Nair, S. S. (2020). Ocular manifestations of endocrine disorders in small animals. Journal of the Indian Veterinary Association, 18, 7-19.


Nowroozzadeh, M. H., Thornton, S., Watson, A., Syed, Z. A., & Razeghinejad, R. (2022). Ocular manifestations of endocrine disorders. Clinical and Experimental Optometry, 105(2), 105-116.


Lemoine, A. N. (1938). Ocular manifestations of endocrine disturbance. Archives of Ophthalmology, 19(2), 184-193.


Costea, C. F. Ocular Manifestations in endocrine diseases.


Kamboj, A., Lause, M., & Kumar, P. (2017). Ophthalmic manifestations of endocrine disorders—endocrinology and the eye. Translational Pediatrics, 6(4), 286.


Buzdugă, C., Turliuc, D., Găleşanu, C., Ciobanu, D., Dimitriu, G., Cucu, A., ... & Costea, C. F. (2016). Ocular manifestations in endocrine diseases. Romanian Journal of Functional & Clinical, Macro-& Microscopical Anatomy & of Anthropology/Revista Româna de Anatomie Functionala si Clinica, Macro si Microscopica si de Antropologie, 15(2).


Van Lanen, K., & Sande, A. (2014). Canine hypoadrenocorticism: pathogenesis, diagnosis, and treatment. Topics in companion animal medicine, 29(4), 88–95. https://doi.org/10.1053/j.tcam.2014.10.001


Eigenmann J. E. (1984). Acromegaly in the dog. The Veterinary clinics of North America. Small animal practice, 14(4), 827–836. https://doi.org/10.1016/s0195-5616(84)50083-7


Gouvêa, F. N., Pennacchi, C. S., Assaf, N. D., Branco, L. O., Costa, P. B., Dos Reis, P. A., & Borin-Crivellenti, S. (2021). Acromegaly in dogs and cats. Annales d'endocrinologie, 82(2), 107–111. https://doi.org/10.1016/j.ando.2021.03.002


Schenck, P. A., Chew, D. J., Nagode, L. A., & Rosol, T. J. (2006). Disorders of calcium: hypercalcemia and hypocalcemia. Fluid, electrolyte, and acid-base disorders in small animal practice, 4, 120-94.



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