# Ophthalmology & Optometry/near-sightedness

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Question
hi. i've read that people who are near-sighted can only see clearly when things are very close to their face -- in some cases within a few inches of their eyes (I mean of course when they're not wearing glasses or contact lenses or anything).

so can a near-sighted person see clearly as long as something is held closely to their eyes, regardless of how near-sighted they are? even with a really really strong prescription of like -20.00, can they still see things that are held extremely closely to their face?

thank you very much.

Answer
Emil,

To some degree, what you're saying is correct. The power of their vision (-2.00, -5.00, etc) corresponds to a focal point / distance.  It is simply a mathematical calculation.
Diopter = 1 / focal length (in meters)

You can flip the equation to figure out what the focal length of a given diopter is...
for example...

If the myopic Rx is -2.00, you would say 2.00 = 1 / x (let x = the focal length)
x would then be 0.5 m, or 50 cm

If the myopic Rx is -5.00, it would be 5.00 = 1 / x
x would then be 0.2 m, or 20 cm

If the myopic Rx is -20.00, it would be 20.00 = 1 / x
x would then .05, or 5 cm

The problem with 'seeing' at 5 cm would be that you would have to shut one eye (both eyes can't converge at a target that close), and that is so close lighting would be an issue.  BUT, if the screen was illuminated (like a smartphone), and the patient closed one eye, they could indeed see at that distance.

Great question, that was fun!  :)

Dr.D
Questioner's Rating
 Rating(1-10) Knowledgeability = 10 Clarity of Response = 10 Politeness = 10 Comment thanks! fantastic answer!

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#### John M. Dovie, OD, FAAO

##### Expertise

As a residency-trained Fellow of the American Academy of Optometry I am able to answer most questions regarding eye and vision health. Anything is welcome, ranging from dry or allergy eyes, bifocal contact lenses, or thoughts on LASIK surgery. As I am not a surgeon, detail-oriented surgical-related questions may be better answered by an ophthalmologist.

##### Experience

Selected to participate in the PCO residency program in Philadelphia at The Eye Institute, where I worked OD and MD specialists gaining invaluable experience in various clinics including glaucoma, cornea and cataract, oculo-plastics, retinal disease, neuro-ophthalmic disease, primary care, emergency medicine, and special populations. Have practiced and trained in numerous settings including hospital, academic, retail and private practice. I earned my Fellowship in the American Academy of Optometry (FAAO). There are currently only about 3000 active fellows worldwide, and there are only about 70 Fellows in the state of Virginia. I currently own and operate my own optometric practice/clinic.

Organizations
American Academy of Optometry, American Optometric Association (Contact Lens/Cornea Section member since 2001), Southwest Virginia Optometric Association, Virginia Tech Alumni Association

Publications
Seminars/Presentations:
“Nyctalopia as the Presenting Sign of Vitamin A Deficiency: A Late Complication of Gastric Bypass Surgery.” Clinical Case Study Poster presented at The American Academy of Optometry Denver, Colorado, December 2006, co-authored with Bradley Lane, OD.
“The Importance of Considering Paranasal Sinus Mucocele as a Differential Diagnosis in Diplopia.” Clinical Case Study Poster presented at The American Academy of Optometry San Diego, California, December 2005, co-authored with Kelly Malloy, OD, FAAO and Cherie Farkash, OD.
“Acute Onset of Halos and Glare: Bilateral Keratitis—An Atypical Presentation of Amiodarone Keratopathy.” Clinical Case Study Poster presented at The American Academy of Optometry Tampa, Florida December 2004. Also Presented to New Jersey Academy of Optometry, Neptune, New Jersey March 2005.
“The Opportunity for an Optometrist to Save a Life.” Clinical Case Study and Grand Rounds Presentation presented at The Pennsylvania College of Optometry, Philadelphia, Pennsylvania, September 2004.
Publications:
“Corneal whorls cause wonder.” Clinical Challenges Quiz, co-authored with Andrew Gurwood, OD, FAAO, Review of Optometry. Published 10/15/2006.
“Acute onset of halos and glare: bilateral corneal epithelial edema with cystic eruptions--atypical presentation of amiodarone keratopathy.” Co-authored with Andrew Gurwood, OD, FAAO. Published February, 2006, Optometry.
“Pondering the posterior polka-dots.” Clinical Challenges Quiz, co-authored with Andrew Gurwood, OD, FAAO, Review of Optometry. Published 5/15/2005.
Professional Involvement:
“AION: Amiodarone-Induced or Anterior Ischemic Optic Neuropathy?” Participated as a peer-review referee for Expert Review of Ophthalmology (London, UK); refereed 10/2006.

Education/Credentials
Bachelor of Science, Cum Laude, Virginia Tech. Bachelor of Science, Pennsylvania College of Optometry. Doctorate (OD), Pennsylvania College of Optometry Residency, Pennsylvania College of Optometry Fellow of the American Academy of Optometry

Awards and Honors
Winner, First Place, "Best Beside Manner" by Our Health Magazine: 2012, 2013, 2014 Winner, First Place, "Best Eye Doctor" by The Roanoke Times: 2013, 2014 Recognized as a Fellow of the American Academy of Optometry, December, 2006 Recipient of the Onofrey G. Rybachok Memorial Scholarship, 2000-2001 Member: The Golden Key International Honor Society Member: The National Biological Honor Society Member: The National Honor Society Eagle Scout awarded 1994

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