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Invest Ophthalmol Vis Sci. 1993 Jul;34(8):2576-80.

Possible errors in the measurement of retinal lesions.

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  • 1Cardiac Surgery Unit, Royal Postgraduate Medical School, London, United Kingdom.



To determine the accuracy of the measurement of structure in the retina from fundus photographs.


A model eye was developed to measure the retinal image size of the Zeiss fundus camera. A x 10 microscope objective with a focal length of 16.41 mm was used together with a microscope graticule.


Under emmetropic conditions the difference between the calculated and the measured magnification was 8.6%. The total change in magnification from myopia to hyperopia was -24.63% to +18.1%. When the camera position was altered with respect to the model eye by +/- 5 mm under myopic conditions the change in magnification was -4.5% and +6.8%. In the hyperopic condition the change was -5.6% to +4.6%.


Measuring the size of structure in the retina from photographs may therefore prove to be inaccurate but in some circumstances determining the percentage change in size may prove more reliable.

[PubMed - indexed for MEDLINE]
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