Vision and EyeCare FAQ
Section 4: Disease of the Eye (Anterior Eye Disease)


4.1 Introduction

This section, and the subsequent section, are only an overview of some of the typical problems and questions that have appeared in the sci.med news groups. It is not a complete discussion of all the potential ocular diseases, which of course, would occupy a complete medical textbook. At this stage it has been broadly classified into anterior and posterior, for want of a better classification scheme.

Also note that the information on eye disease is only provided as an information service and does not replace examination by an eyecare professional.

Some attempt has been made to include references to World Wide Web pages which may have more information and/or graphics on the disease.




4.2 Conjunctivitis

Conjunctivitis is an inflammation of a mucous membrane and therefore in most types there is a red eye, thickening of the conjunctival tissue and some discharge of mucous or mucous and inflammatory cells. The causes of Conjunctivitis include; bacterial infection, viral infection and allergic reactions.

Typical bacterial conjunctivitis, is caused by the common staphylococcus and diplococcus pneumoniae to the less common organisms of the haemophilus group. Infection is generally in both eyes with the patient experiencing discomfort in the form of a "smarting" and grittiness, moderate photophobia, but minimal pain. Discharge from the infection causes the well known symptoms of eyelids stuck together on wakening or having a "crusty" appearance. Bacterial conductivities responds well to antibiotic treatment.

Viral infections, sometimes caused by adenoviruses which are often involved in upper respiratory tract infections, cause inflammation of the membrane on the back of the eyelid.

Allergic conjunctivitis results from hypersensitivity to exogenous antigens. There are many forms, with some examples being, profuse watering due to hay fever, chronic inflammation as a result of a reaction to locally applied drugs. The treatment is to remove the antigen and use of vasoconstrictors.




4.3 Dry Eyes

- Causes [Details to be added ]
- Treatments, in-eye solutions, tear duct plugs [details to be added ]

Web site references:

URL: Dry Eye Syndrome from the Contact Lens Institute.
URL: http://www.eyecarecontacts.com/ The EyeCare Connection and CyberLens
URL: http://www.sjogrens.com/ Sjogrens Sydnrome Foundation



4.4 Eyelid Problems

Styes are common eyelid problems and are a type of "boil" involving an eyelash follicle. There is generally a tense swelling with redness and pain, until the abscess escapes. Application of local heat, using a compress can assist in easing the pain and bring the stye more quickly to a "head".

Internal stye, tarsal cyst or chalazion is a chronic granuloma of the Meibomain gland of the eyelid. This manifests as a small hard spherical lump within the eyelid, often easily felt but not seen. Treatment varies, depending on the size and/or associated discomfort which may be caused by the swelling of the eyelid.

Other common eyelid problems include blepharatis, which is a kind of "dandruff" of the eyelid margin. The eyelid margins are red-rimmed with flakes and scales among the eyelashes. Burning discomfort and itching comes and goes. Treatment involves cleansing of the eyelid margin, using sterile wipes or eye ointments.


See also:
URL: http://www.eyecarecontacts.com/
The EyeCare Connection and CyberLens



4.5 Keratoconus

Keratoconus (conical cornea) is an recessive inherited condition usually apparent between the ages of 10-25yrs. Incidence of the condition is approximately 1 in 5,000.

The condition manifests as a thinning of the corneal apex, or central area of the cornea. With the weakening of the tissue there is a bulging of the tissue which increases the myopia of the affected eye. Initial correction is via spectacles whereby reasonable vision can be attained. Subsequent treatment is via a rigid contact lens which will provide a new front surface to the optical system of the eye.


There is more information about this condition from the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) study at:
- http://www.optometry.ohio-state.edu/CLEK/clek.htm

Other sources of information for readers in the USA are:
- National Keratoconus Foundation (310) 855-6435
- National Eye Institute (301) 496-5248
- NORD (National Organization for Rare Disorders) 1-800-799-6673
- US Public Health Service 1-800-336-4797



4.6 Herpes Zoster ("Shingles")

Affects the eye by encroaching from a skin lesion or starts on the eye. The appearance is white pustules, similar to cold sores in the mouth. This disease is treated by early antiviral treatment.




4.7 Effects of Radiation on the Eye



4.7.1 General Effects of Radiation on the eye

UV radiation is classified as:
UV-A
UV-B (280-315nm)
UV-C (200-280nm)

Potential hazards from UV radiation are photokeratitis, conjunctivitis and lenticular cataracts (Parrish et .al)

- UV radiation less than 320nm causes photokeratitis and conjunctivitis
- large doses of wavelengths greater than 350nm are required to induce cataract formation, perhaps of the order of 0.5 to 1.0 MJ/m^2



4.7.2 Visual Displays and Radiation

The details of the radiation levels are given below (Liden et .al):

UV-A Detector's Direction                                    UV-A (W/m^2, mean)
Towards the screen at 60cm distance                     0.03
Towards the ceiling (VDT operators)                     0.04
Towards the ceiling (other office workers)              0.13

The author's conclusions were that UV-A emmission from VDT's is very low and can not be of biological relevance in comparison to normal UV-A exposure. Also that VDT work and health is a multi-factorial problem and that a common single-factor explaination of ill health during VDT use is not viable.

In another paper (Elliot et .al) it reports that there is no ocular hazard from the RF emmissions from VDTs. Also that VDTs emit no UV radiation below 350nm.




4.8 Iridology

This is postulated as a means of determining general health by variations in the iris pigment and structure.

Some papers and references (contributed by Roberty Sekuler test and debunk iridology (Simon et .al), Knipschild P.)

Web resource: http://www.itlnet.com/natural/



Index:

© Grant Sayer , email: grants@research.canon.oz.au
 

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