Vision and Eye Care FAQ
Frequently Asked Questions concerning vision and eye care.
This FAQ about Vision and Eye
Care
was compiled and written by grants@research.canon.com.au (Grant Sayer)
with numerous contributions by others.
DOCUMENT: Frequently-Asked-Questions for sci.med.vision
REVISION: $Date: 2007/09/25 00:06:32 $, $Revision: 1.2 $
AUTHOR: Grant Sayer BOptomBSc
CONTRIBUTORS: Barbara La Scala, Scott Fitz, Ronald Jones,
David Nelson M.D, Nathan Schwade PhD, Alex Eulenberg,
Darren Berar, W.Lee Wan M.D, Robert Sekuler
COPYRIGHT: Copyright (C), 1995 Grant Sayer
Permission to copy all or part of this work is
granted provided that the copies are not made or
distributed for resale (except a nominal copy fee
may be charged), and provided that the AUTHOR,
COPYRIGHT and NO WARRANTY sections are retained
verbatim and are displayed as is. If anyone needs
other permissions that aren't covered by the above
please contact the author.
NO WARRANTY: THIS WORK IS PROVIDED ON AN AS IS BASIS. THE AUTHOR
PROVIDES NO WARRANTY AND PROVIDES THE INFORMATION
TO ASSIST UNDERSTANDING OF HUMAN VISION AND EYECARE.
THIS INFORMATION DOES NOT REPLACE PERSONAL EXAMINATION
BY AN EYECARE PROFESSIONAL AND THE AUTHOR AND
CONTRIBUTORS DO NOT ACCEPT ANY RESPONSIBILITY FOR
MISUSE OF THIS INFORMATION. IF ANY READER HAS CONCERNS
ABOUT THEIR VISION OR HEALTH OF THEIR EYES EXAMINATION
BY AN EYECARE PROFESSIONAL IS THE ONLY RECOMMENDED
COURSE OF ACTION.
AVAILABILITY: This FAQ is available from:
(WWW) URL http://www.webcom.com/~optcom/
(WWW) URL: http://spectacle.berkeley.edu
(Gopher) gopher://eyesite.optometry.ohio-state.edu
(Ascii) email - 'grants@research.canon.oz.au'
ARCHIVES: sci.med.vision articles are currently being
archived by Grant Sayer. A summary of topics
will be placed on a listserver as time permits :-)
IMAGES: Some basic images (TIFF/BMP/GIF) of anatomy of the
eye, diagrams of refractive problems, common
eye diseases are maintained by the author. Please
email for further information.
1.1: What is Myopia ?- Myopia is often referred to as short-sightedness or near-sighted. ...
1.2 What is Hyperopia ?- Hyperopia is often referred to as long-sightedness or far-sighted....
1.3 What is Emmetropia ?- Emmetropia is just another name for an eye that has no optical defects and ...
1.4 What is Astigmatism ?- An astigmatic eye generally has two different meridians, at 90degrees to ...
1.5 What is Presbyopia ?- Presbyopia describes the condition whereby the amplitude of accommodation, ...
1.6 How is Visual Acuity Measured- Visual acuity is the measure of the sensitivity of the visual system. ...
2.0 Terminology of Spectacles- Lenses commonly used for spectacles are either spherical powered ...
2.1 How to read a glasses prescription- A prescription for spectacles will generally contain the powers for lenses ...
2.2 Why the difference between the way Optometrists and Ophthalmologists write the prescription ?- There are two ways of writing the prescription; referred to as plus-cyl ...
2.3 How to convert between the two forms- To convert from plus-cyl form to minus-cyl form use the following steps:...
2.4 Eyeglass Lens materials- Spectacle lenses are made of two main types of materials - plastic or glass....
2.5 Types of Spectacle Lenses- + Single Vision ...
2.6 Ultra Violet absorption and Lenses- Spectacle lenses, depending on the type of material will absorb varying ...
2.7 Standards Requirements for Spectacle Lenses- International and local standards define the properties of lenses that ...
2.8 Cost of frames- Varies depending on the type of material, eg plastic frame to titanium metal....
2.9 Cost of lenses- Like frames varies with the type of the material. Also depends if the ...
2.10 Reducing the edge thickness of the lens- Since edge thickness is a function of lens power, centre thickness ...
2.11 Internet Ordering of Prescriptions and Sunglasses- The are a wide variety of companies that advertise on the internet ...
3.0 WWW Sites on Contact Lenses- URL: http: //www.sna.com/etonline/...
3.1 Difference between soft and hard contact lenses- Soft lenses are manufactured from a plastic hydrogel polymer, ...
3.2 How to Read a Contact Lens Description:
3.2 Types of Soft Contact Lenses- Soft contact lenses vary depending on either the refractive correction that ...
3.2.1 Spherical- Single prescription power 360 degrees around the lens....
3.2.2 Toric- Contains both a spherical and cylinder component to correct prescriptions ...
3.2.3 Disposable- Spherical or toric contact lenses which are designed to be worn for a ...
3.2.4 Extended Wear- Lens manufactured from a high-water content material and/or with a very ...
3.2.5 Bifocal Lenses- There are a variety of designs in bifocals, essentially all ...
3.3 Types of Rigid Contact Lenses- Rigid contact lenses also vary depending on the material and the design of ...
3.3.1 PMMA- Original material used in the construction of hard contact lenses....
3.3.2 RGP- Combination of PMMA and other polymers to increase the oxygen permeability ...
3.3.3 Spherical- same as for soft contact ...
3.3.4 Toric- Can be either toric periphery, which is used for fitting reasons, ...
3.3.5 Bifocal- The different types include;...
3.4 Costs of Contact Lenses- Varies depending on the type of contact ...
3.5 Solutions required for CL maintenance- In general all contact lenses, whether soft of rigid type, will ...
3.6.1 Why do I have to clean my Contact Lenses ?- Cleaning removes surface debris and bacteria that may adhere to the ...
3.6.2 Why is there a limit to the length of wearing time ?- The cornea the clear part of the eye, is avascular or without a blood supply....
3.6.3 Can I lose the lens behind my eye ?- Short answer is no. The conjunctiva, the tissue that covers the white ...
3.6.4 How do I tell if I've lost the lens from my eye?- Cover the other eye to determine if vision is still clear from the eye where ...
3.6.5 How can I tell if I've put them in the wrong eye ?- Check the vision of each eye by covering alternate eyes with your hand....
3.6.6 How to tell if the lenses are inside out ?- Soft lenses will appear as a smooth dish shape when placed on the end of ...
3.6.7 How do I know when to dispose of my disposable lenses ?- The lenses will not automatically self-destruct at the end of the wearing ...
3.6.8 Can I store my lenses in tap water ?- Short answer - No !. There are a number of nasty micro- organisms,...
3.6.9 Can I store my lenses dry ?- Soft lenses - definitely not !. Soft lenses stored dry will turn into ...
3.6.10 How long does it take to adapt to new lenses ?- Soft lenses are generally worn for 2-4hrs on the first day and the wearing ...
3.6.11 Why do I have to use protein cleaner ?- Contact lenses are exposed to a complex environment whilst on the eye. ...
3.6.12 Can I use eyedrops with my contact lenses ?- In general eyedrops shouldn't be used with contact lenses because the lens ...
3.6.13 How do I get around dryness with contact lenses ?- Try using an in-eye lubricant. There can be some dryness if you work in ...
3.7 Risks and Benefits of Contact Lenses
3.8 Mail order contact lenses- Easiest method to locate the contact lens suppliers on the internet ...
3.9 Making your own saline - risks- Greatest risk in manufacturing your own saline is the acanthamoeba. ...
4.1 Introduction- This section, and the subsequent section, are only an overview of some ...
4.2 Conjunctivitis- Conjunctivitis is an inflammation of a mucous membrane and therefore in ...
4.3 Dry Eyes- - Causes [Details to be added ]...
4.4 Eyelid Problems- Styes are common eyelid problems and are a type of boil involving an ...
4.5 Keratoconus- Keratoconus (conical cornea) is an recessive inherited condition usually ...
4.6 Herpes Zoster ("Shingles")- Affects the eye by encroaching from a skin lesion or starts ...
4.7.1 General Effects of Radiation on the eye- UV radiation is classified ...
4.7.2 Visual Displays and Radiation
4.8 Iridology- This is postulated as a means of determining general health by ...
5.1 Floaters and Spots in the Field of View- Floaters (muscae volitantes - flying flies) are spots before the eyes ...
5.2 Macular Degeneration- The macular is the innermost part of the central retina; an area where ...
5.3 Retinal Detachments- The retina is one of the three layers of the human eye. The innermost ...
5.4 Diabetes and The Retina- Diabetes causes a number of retinal changes which can include haemorrhages,...
5.5 Retinitis Pigmentosa- Retinitis Pigmentosa is a degeneration of the retinal pigment epithelium....
5.6 Glaucoma- Glaucoma is a symptomatic condition and not a disease sui generis. It ...
5.7 Cataracts- Cataracts are opacifications of the crystalline lens of the eye, causing ...
5.8 Uveitis:- [ TBD - details to be added ]...
5.9 Ocular Migraines:
5.9.1 Introduction:- The following is an attempt to give an_introduction_only to this vast ...
5.9.2 Classification of migraine:- I. Common migraine. The comprises about 80% of those with migraines. It is ...
5.10 Chorioditis:- Choroiditis is an inflammation of the choroid, the second coat of ...
6.1 Strabismus (Turned Eye)- A squint or strabismus is a failure of the two eyes to look at the same ...
6.2 Amblyopia ("Lazy Eye")- Amblyopia is defined by Schapero et al. as the condition of reduced ...
6.3 Problem(s) When Wearing Glasses- - Reflections....
6.4.1 Vision Therapy Introduction- Common problems that require vision therapy ...
6.4.2 Vision Therapy: Bates Method- Vision therapy, especially people claiming improvement of vision ...
7.1 Defective Colour Vision:- Defects in colour vision, often incorrectly referred to as colour ...
7.2 Classification of Congenital Colour Vision Defects
7.3 Classification of Acquired Colour Vision Defects
7.4 WWW Resources on Colour
8.0 WWW Resources on Refractive Surgery:- URL: http://www.eyenet.org/public/faq/refractive_surgery_faq....
8.1 Types of Refractive Surgery- There are basically 4 main operations performed for correction of ...
8.2 Description of the Procedures:
8.2.1 Suitability for each procedure
8.3 Comparison of RK, PRK and ALK and LASIK:- PRK: involves less than 5% the depth of the cornea, typically. ...
8.4 Complications of the Procedures- PRK Side Effects -...
8.6 Criteria for Suitability of Procedures- PRK: The following guidelines are suggested for those individuals suitable ...
8.7 Personal Experiences of Refractive Surgery- The following information details the personal experiences that some ...
8.7 Personal Experiences of Refractive Surgery #2- The following information is details of experiences of patients ...
8.7 Personal Experiences of Refractive Surgery #3- The following information was kindly contributed by Dr Robert Maloney M....
8.7 Personal Experiences of Refractive Surgery #4- ALK:
8.7 Costs of Surgery:
8.8 Further information on Procedures:- The supplement to volume 9 No. 2 (March - April 1993) of the Journal ...
8.9 Location of Places Performing Surgery- URL: http://www-or.stanford.edu/~mob/...
8.10 OrthoKeratology- Fitting RGP contact lenses to change shape of cornea....
10.0 Internet Vision/Health Resources- A large number of resources specific for ophthalmology/optometry ...
10.1 Guide to On-Line Medical Resources- An extensive list of Internet Medical resources are listed in the ...
10.2 Images of Eye Conditions/Diseases- Images of retinal and eye conditions as GIF/TIFF files ...
11.0 Mailing Lists- A number of mailing lists are located on the Internet which deal with ...
11.1 RPList
11.2 CVNet- This list deals with colour and vision research. ...
11.3 ColorCat- This list deals with Color ...
11.4 HMatrix- [ Details to be added ]...
11.5 BlindFam- This list is for the discussion of all aspects of family life as affected ...
11.6 BlindNews- This list deals with issues of the visually handicapped. ...
11.7 MedNet- [ Details to be added ]...
11.8 EyeMove- This list is for scientists and clinicians interested in all aspects of ...
11.9 LiveEye- This list also deals with colour and vision research. ...
11.9a National Marfan Foundation
11.10 PupilNet- From the announcement page......
11.11 Sjogren's Syndrome List (SS-List)- This list is for the discussion of sjogren's syndrome....
11.12 Ophthalmic Photography and Imaging Mailing List (OPTIMAL)- This list is for the discussion of ophthalmic photography ...
11.13 Ophthalmogenetics Mail List- This list is for the discussion of Ophthalmogenetics (genetics ...
11.14 Myopia Research mailing List:
12.0 World Wide Web (WWW)- Other related Web servers include :...
13.0 Email for Optoms/Ophthals & Net Resources- Currently the national board for USA is on the internet ...
13.1 Commercial Interests on the Net: