Eye in Systemic Illness

It is said eyes are a window to the soul. But not many know that the eyes are a window to the health of a person. When the doctor looks inside the eye using an ophthalmoscope he is able to view the blood vessels in the retina. This is the only part of the human body where we can see even minute changes in   the blood vessels like thickening of the walls or small cholesterol crystals inside the vessels. Sometimes doctors can even diagnose diabetes, hypertension and hypercholestremia by just looking at the eye.

Disease	Ocular presentation
Myaesthenia gravis	Ptosis and diplopia
Hyperlipidaemia	Xanthelasma, arcuscornealis and presenile cataract
Marfan’s syndrome	Myopia, dislocated lens and retinal detachment
Haematological disease, e.g. anaemia	Retinal haemorrhages, Roth spots and cotton wool spots
Leukaemia and lymphoma	Uveitis, retinitis, optic nerve infiltration and orbital disease
Malignant hypertension	Disc swelling, retinal haemorrhages, hard exudates and cotton wool spots
Albinism	Myopia, astigmatism and nystagmus
Neurofibromatosis (type 1)	Eyelid neurofibromas and Lisch nodules on the iris
von Hippel-Lindau disease	Retinal capillary haemangioma
Diabetes	Retinopathy, and third and sixth nerve palsies
HIV/AIDS	Herpes zoster ophthalmicus, microangiopathy, CMV retinitis, squamous cell carcinoma of conjunctiva and cranial nerve palsies
Thyroid eye disease	Proptosis, optic neuropathy, lid retraction, restrictive myopathies and soft tissue swelling
Syphilis	Uveitis, chorioretinitis and optic Atrophy
Rheumatoid arthritis, SLE and other collagen vascular diseases	Scleritis, episcleritis and keratitis
Ankylosing spondylitis, psoriasisand other seronegative spondyloarthropathies	Uveitis
Eczema	Keratoconjunctivitis, cataracts and keratoconus

The following conditions affect the eye to an extent that they may first present through their ocular manifestations, or their ocular manifestations are likely to be significant in confirming the diagnosis.

Diabetes mellitus

Diabetes maybe diagnosed for the  first time on a routine eye examination. Diabetes affects small blood vessels and can be particularly destructive in the eye. Reduced blood supply due to narrowing of blood vesssels causes hypoxic damage to the tissues of the eye, particularly the retina. Diabetes can cause of early cataracts, due to excess glucose interfering with the metabolism of the crystalline lens.

The blood vessels of the retina can bee seen directly using an ophthalmoscope. Similar changes maybe seen in the blood vessels of the kidney and heart and hence by looking at the eye we can even predsict the health of the kidneys and heart.

Hypertension

An Ophthalmologist maybe able to diagnose hypertension by just looking into the eye. Hypertension can cause the blood vessels to become narrow. Severe retinal changes are normally associated with a diastolic pressure >110 mm Hg and/or a systolic pressure of systolic pressure of >220 mm Hg.

Complications of hypertensive retinopathy include optic neuropathy and central vein or artery occlusions. These can cause defective vision.

Hyperthyroidism

Hyperthyroidism may cause proptosis, which may be the first sign of the condition. This may be unilateral or bilateral. The ocular complications of thyroid eye disease may include corneal ulceration and visual loss.

Hyperlipidaemia

White circles around the cornea is called arcus. This maybe seen in some people from birth. If it appears around 30 to 40 years of age it is called arcus juvenilis and maybe associated with elevated cholesterol levels.

Connective tissue disorders

Those disorders which particularly affect joints can also inflame the eye, causing red eye (scleritis or uveitis). Connective tissue disorders include: Rheumatoid arthritis , SLE, Ankylosing spondylitis , Ulcerative colitis. These can be associated with Uveitis, papilloedema, dry eye, episcleritis or scleritis, eyelid tightening and telangiectasia. are common. Retinal vasculitis may cause sudden unilateral transient or permanent visual loss.

Multiple sclerosis

Often the first nerve to be affected by the acute demyelination of multiple sclerosis (MS) is the optic nerve, causing optic neuritis. Optic neuritis causes marked dimunition of vision which may spontaneoulsly recover. These patients require MRI evaluation and neurology consultation.

Myasthenia gravis

Myasthenia gravis often presents as ptosis. The picture is of fluctuating, asymmetric external ophthalmoplegia with ptosis and weak eye closure. Patients often have an inability to maintain upward gaze.

Toxoplasmosis

This is an infection by Toxoplasma Gondi which is transmitted fromn cats. It causes retinochoroiditis. Active infection in the eye is more common when there is an immune deficiency such as AIDS, or after transplant. Prompt treatmenmt is required to prevent permanent blindness.

Eye conditions and their associations

Cataracts

Most cataracts are age-related but they maybe associated with underlying conditions. They are more common in patients with diabetes and Down's syndrome. They may be associated with steroid use, hormone deficiencies, previous eye trauma, congenital rubella and some congenital conditions.

Uveitis

Most cases of uveitis do not have a definitive cause. In some cases they maybe associated with systemic diseases like inflammatory disorders such as rheumatoid arthritis,  infections like tuberculosis and with infestations like toxoplasmosis.  Uveitis might be expected in any disease process which has the capacity to affect joints, given that the eye is a modified joint.

Central retinal vein occlusion

Central retinal vein occlusion (CRVO) is associated with hypertension, diabetes, smoking, hyperlipidaemia, hyperviscosity states, glaucoma, thrombophilia and vasculitis.

Central retinal artery occlusion

Central retinal artery occlusion (CRAO) should prompt a search for a source of atherosclerosis, emboli or inflammatory causes. It is a common presenting feature of carotid artery stenosis.

Amaurosisfugax

Amaurosisfugax is a transient obscuration of vision. It is due to short duration ischaemia caused by  emboli, thrombus vasospasm, or haematological problems. It is also seen in carotid artery stenosis.

Pupillary abnormalities

The size of the pupil can be affected by diseases like Horner's syndrome, use of cocaine, some eye drops and cranial nerve palsies.

Abnormal eye movements

Abnormal eye movements and squints are found in many conditions affecting the cranial nerves or their corresponding brainstem nuclei. These include cerebrovascular accidents, aneurysms and diabetes. Transient paralysis of cranial nerves III, IV or VI may occur during ophthalmoplegic migraines and may go on for days or weeks. These are rare and recovery is full.

HIV/AIDS

There are many ophthalmic features associated with AIDS and, very occasionally, suspicion of AIDS is raised by a first presentation with ophthalmological problems. The ocular problems can be summarised as follows: Eye lid tumors, recurrent corneal infections, uveitis ( red eye ) , squint, blurred vision.

Syphilis

Acquired syphilis commonly results in keratitis. Less commonly, there is uveitis, chorioretinitis and neuroretinitis. Babies with congenital syphilis tend to have uveitis and keratitis; later on there is a pigmentary retinopathy

Albinism

This is a congenital condition of lack of pigmentation and includes the iris. Individuals with albinism have a rather transparent iris so that the red reflex is easily seen, although its colour varies from blue to brown. Most patients have deteriorating or poor vision with nystagmus. They are also at increased risk of ocular melanoma.

Down's syndrome

This condition involves multiple physical signs and associations. Children with Down's syndrome commonly have an upward slant to the eyes and have epicanthal folds at the inner corners of the eyes giving a Chinese appearance. They may have nystagmus or congenital cataracts and frequently have poor vision with short sight and/or squint. As they become older they are more likely to have sticky eyes, blepharitis and conjunctivitis and, in their teens and twenties, they are more at risk of developing cataracts and keratoconus.

Cancer

Cancer can arise in or metastasise to the eye. The most common primary eye tumour is a choroidal melanoma. See separate articles Eye and Optic Nerve Tumours, Retinal Tumours and Retinoblastoma.

Anaemia

Haemorrhage, cotton wool spots, subconjunctivalhaemorrhage and, if vitamin B12 is low, optic neuropathy may occur. The severity is correlated with the severity of the anaemia.

Visual Fields.

The visual field is the portion of the subject's surroundings that can be seen at any one time. The field of vision can give an idea about many eye problems. Eye diseases can affect the fields of vision in characteristic patterns.

Central field loss

·         Age-related macular degeneration.

·         Optic neuropathy.

·         Leber's optic atrophy.

·         Macular holes.

·         Cone dystrophies

·         Retinal artery occlusion.

Peripheral field loss

• ·         Glaucoma
• ·         Retinal detachment.
• ·         Retinitis pigmentosa.
• ·         Chorioretinitis.
• ·         Branch retinal artery occlusion

Hemi anopia: One half of vision lost.

Depending on the part of the brain affected the filed loss will have charahteristic diagnostic paterns.

• ·         Brain tumors
• ·         Stroke