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OPHTHALMIC IMAGE
Year : 2022  |  Volume : 2  |  Issue : 3  |  Page : 839

Beam aberration through progressive glasses


Department of Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India

Date of Web Publication16-Jul-2022

Correspondence Address:
Dr. Amber A Bhayana
Dr. Rajendra Prasad Centre, AIIMS, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_2734_21

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How to cite this article:
Bhayana AA, Khokhar SK, Prasad P, Anshida K. Beam aberration through progressive glasses. Indian J Ophthalmol Case Rep 2022;2:839

How to cite this URL:
Bhayana AA, Khokhar SK, Prasad P, Anshida K. Beam aberration through progressive glasses. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 19];2:839. Available from: https://www.ijoreports.in/text.asp?2022/2/3/839/351147



A progressive,[1] presbyopic glass can be identified by the progressive magnification it causes to the letters seen across it (size increasing downwards) [Figure 1]a. This might be missed in case of small magnitude of near add where differential magnification might be difficult to identify. We describe a simple, novel, yet foo proof method to identify the glasses. The illumination beam from indirect ophthalmoscope (ideally symmetrically circular) [Figure 1]b when passed through the glasses manifests distortion in the inferior half [Figure 1]c. The distortion is alike when different colours of lights are used [Figure 1]d, [Figure 1]e, [Figure 1]f. The distortion is due to different converging powers in different zones of the glasses, the same factor being responsible for differential magnification.
Figure 1: (a) Reading letters through progressive glasses (note the increase in size of letters in downward direction); (b) Virgin beam from indirect ophthalmoscope (note the circular symmetry); the beam passed through progressive glasses show distortion for (c) white light; (d) blue light; (e) green light; (f) red light

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Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Wolffsohn JS, Davies LN. Presbyopia: Effectiveness of correction strategies. Prog Retin Eye Res 2019;68:124-43.  Back to cited text no. 1
    


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