Eye Diseases And Eye-related Topics

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Eye diseases and eye-related topics
Anatomy of the eye	Introduction
Cataract	Lacrimal gland problems
Color Blindness	Macular degeneration
Conjunctivitis	Optic nerve problems
Cornea problems	Retinal problems
Eye infections and inflammatory eye conditions	Signs and symptoms of eye disease
Eyelid problems (entropion, ectropion etc.)	Trauma to the eye
Eyesight problems (refractive errors)	Uveitis
Glaucoma

[edit] Introduction

Eyesight is one of the five senses, perhaps the most important one, that keeps us in touch with the environment. The trigeminal nerve is a powerful nerve that provides the surface of the eye (the cornea) with sensitive nerve fibers.

The optic nerve supplies the retina with the necessary nerve fibers for visual perception, like a living light sensitive camera. The structure of the eye is complex and will be explained below in a brief outline under "eye anatomy". It will be further detailed where it is needed in each of the subchapters. Children's eyes are more difficult to assess as they find it more difficult to sit still and cannot answer questions as precisely as adults. Yet, in order to avoid the development of a lazy eye, called "amblyopia", they need regular eye doctor visits as is explained in this link.

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[edit] Eyelid Problems (Entropion, Ectropion etc.)

When the eye lids loose elasticity with age the tracking mechanism of the eye lids is abnormal. The lower eye lids can turn inward (entropion) or it can turn outward (ectropion) .

Similarly, there is a site with more detail of what to do when the patient has an entropion. This site shows pictures before and after entropion surgery that demonstrate what can be done to help these patients get normal looking eyes with normal eye lid function.

[edit] Optic Nerve Problems

Common causes of optic nerve problems (choose one)

Higher optic pathway lesion

Optic atrophy

Optic neuritis (=papillitis)

Papilledema

Retrobulbar neuritis

Toxic amblyopia

[edit] Introduction

The optic nerve forms the whitish/yellow knob that the physician sees through the ophthalmoscope or the slit lamp at the back of the eye. Physicians call it the "optic disc" or in Latin the "papilla".

This is where all of the nerves that collect information from the retinal nerve cells bundle together and form the beginning of the optic nerve. When the optic nerve leaves the eye ball (also called "bulb") in the back, it is still within the eye cavity for a short stretch. This part of the optic nerve is termed "bulbar portion" or orbital portion of the optic nerve. This terminology becomes important when it comes to disease conditions.

For instance, we will learn more about "papilledema" below, which is a swelling of the optic disc or papilla (=edema of the papilla) from high blood pressure.

If there is inflammation of the optic disc, this is called "papillitis" (="itis" meaning "inflammation", therefore "inflammation of the papilla). Another term is "retrobulbar neuritis", which is a nerve inflammation of the bulbar portion (=orbital portion) of the optic nerve.

All of these conditions are explained under the Links of the above table in more detail. I will also deal with toxic amblyopia (blurred vision from toxins), optic atrophy (atrophy of the optic nerve) and interruptions of higher optic pathways at the optic chiasm and in the brain substance.

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Optic nerve problems

[edit] Retinal Problems

Retinal problems
Name of condition:	Cause and description:
Central retinal artery occlusion	from a dislodged blood clot in an artery
Central retinal vein occlusion	occurs in older persons. Common with glaucoma, diabetes, high blood pressure and blood clotting disorders
Diabetic retinopathy	the longer diabetes has been present , the worse the condition usually is
Hypertensive retinopathy	poorly controlled high blood pressure causes this condition. Also in toxemia of pregnancy
Macular degeneration	this condition is age-related and leads to progressive loss of vision, more common in whites than blacks; it may be hereditary
Retinal detachment	occurs in trauma, with myopia or after cataract surgery (often with a tear); also happens without a tear in diabetics or in patients with sickle cell disease
Retinitis pigmentosa	loss of night vision, later also blind spots. Sometimes associated with hearing loss (hereditary form)
Retinopathy of prematurity	abnormal retinal blood vessels in prematurely born babies. Depending on the degree, vision ranges from normal to blindness

[edit] Introduction

Retinal problems can happen in a variety of different settings. For instance, diabetes can lead to a diabetic neuropathy, uncontrolled high blood pressure to a hypertensive neuropathy.

But aging by itself can lead to loss of sight by the development of age related macular degeneration. All of these conditions and the ones listed in the table above do lead to loss of vision, either slowly (most conditions) or suddenly (retinal detachment), all of that without any pain. If a prior eye condition such as uveitis or glaucoma exists, pain can be present and comes from the preexisting condition, not from the retinal problem.

[edit] Signs and symptoms

These are different for the various conditions and can be found in more detail under the links of the table above where each retinal problem is described.

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Retinal problems

References:

1. The Merck Manual: Eye disorders

2. Eye conditions: http://www.stlukeseye.com/Conditions/

3. Karolinska Institute Library eye disease links

4. Ferri: Ferri's Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.

5. Rakel: Conn's Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier