Indian Journal of Ophthalmology

OPHTHALMIC IMAGE
Year
: 2020  |  Volume : 68  |  Issue : 7  |  Page : 1452-

The bifocal scotoma


Amber A Bhayana, Vinit Tanwar 
 Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Dr. Amber A Bhayana
Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
India




How to cite this article:
Bhayana AA, Tanwar V. The bifocal scotoma.Indian J Ophthalmol 2020;68:1452-1452


How to cite this URL:
Bhayana AA, Tanwar V. The bifocal scotoma. Indian J Ophthalmol [serial online] 2020 [cited 2024 Mar 29 ];68:1452-1452
Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?2020/68/7/1452/287557


Full Text



An ellipse of the dark area is always seen whenever the light is allowed to pass through bifocal glasses [[Figure 1]a- white arrow]. This ellipse corresponds to the junction of the distant and near lenses and we believe it to cause some form of scotoma to the person whose mechanism [Figure 1]b we hypothesize to be very similar to roving ring scotoma,[1] in case of aphakic glasses. Differential refraction, causing differential prismatic deflection, at the junction of 2 optically dissimilar surfaces forms a scotoma between the 2 zones as shown. The same mechanism partly also contributes to negative dysphotopsias.[2]{Figure 1}

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Conflicts of interest

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References

1Welsh RC. The roving ring scotoma with its jack-in-the-box phenomenon of strong-plus (aphakic) spectacle lenses. Am J Ophthalmol 1961;51:1277-81.
2Mamalis N. Negative dysphotopsia following cataract surgery. J Cataract Refract Surg 2010;36:371-2.