Thin Optic Nerve and Astigmatism Issues in Myopia - Ophthalmology

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Understanding the relationship between thin optic nerves, astigmatism, and myopia is crucial for managing eye health, especially in individuals with high myopia. High myopia, defined as a refractive error greater than -6.00 diopters, can lead to various ocular complications, including changes in the optic nerve and the development of astigmatism.

1. Optic Nerve Thickness: The average thickness of the optic nerve fiber layer (ONFL) is indeed a significant indicator of optic nerve health. In your case, an average thickness of 82 and 78 micrometers is below the normative range, which typically hovers around 100 micrometers or more. While a thinner optic nerve does not automatically indicate disease, it can be associated with conditions such as glaucoma or other optic neuropathies. It is essential to correlate these findings with your visual field tests and other clinical assessments. Since your visual fields are currently normal, this is a positive sign, but continued monitoring is advisable, especially given your high myopia.

2. Astigmatism Assessment: Astigmatism is characterized by an irregular curvature of the cornea or lens, leading to blurred vision. The variability in your astigmatism measurements (ranging from 75 to 125 degrees) suggests that your corneal shape may be changing or that there may be measurement inconsistencies. The degree of astigmatism can be assessed using a refractive examination, and the appropriate correction should be based on the most consistent readings. If your glasses are prescribed for 75 degrees of astigmatism but you notice significant blurriness in low-light conditions, it may indicate that your prescription needs adjustment.

3. Impact of Astigmatism on Vision: Poor vision in dim lighting can indeed be related to insufficient correction of astigmatism. Astigmatism can cause light to focus at multiple points on the retina, leading to blurred or distorted vision, particularly in low-light situations. If your glasses do not adequately correct your astigmatism, this could contribute to your difficulty seeing clearly in the dark.

4. Pupil Size and Night Vision: Your reported pupil sizes of 6.1 and 6.8 mm are within a normal range for adults. However, larger pupils can lead to increased aberrations, especially in low-light conditions, which may exacerbate issues related to astigmatism. If your pupils are larger than average, they may allow more light to enter the eye, but they can also increase the impact of any refractive errors, leading to more noticeable blurriness or halos around lights at night.

5. Further Investigations: Given your concerns and the findings from your OCT and visual field tests, it may be beneficial to undergo additional assessments. These could include a comprehensive eye examination focusing on corneal topography to evaluate the shape of your cornea, as well as a detailed refraction to ensure your glasses prescription is optimal. If there are any concerns about the health of your optic nerve or if you experience any changes in your vision, further imaging studies or referrals to a specialist may be warranted.

In conclusion, while your current optic nerve thickness is below average, the absence of visual field defects is reassuring. Your astigmatism variability and difficulties in low-light conditions suggest that your prescription may need reevaluation. Regular follow-ups with your eye care provider are essential to monitor your eye health, especially given the risks associated with high myopia.