Question:
How can the pterygium result in decrease vision in this case?
Answer:
Although pterygia affecting the visual axis can result in decrease vision especially in scotopic conditions due to dilation of the pupil. In addition to physically affecting visual axis pterygia can induce astigmatism.
In this case there is an astigmatism of 4.5D (denoted by red arrow). There is significant flattening of the ocular surface (denoted by red *)
Question.
What would you do in this particular case assuming cataract is the main cause of visual decline? What are the important points to consider?
Answer:
When considering cataract surgery biometry is undertaken to determine what power of lens to place inside the eye to achieve the desired refractive outcome. The main parameters used to calculate the lens power is the corneal curvature and the axial length of the eye. Given that the pterygium has resulted in 4.5D of astigmatism this would have a profound influence on the lens calculation. It is therefore most appropriate to consider dealing with the pterygium before undertaking biometry.
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