Visual Impairment: Key Questions and Insights on Eye Health

Q: Visual Impairment: Key Questions and Insights on Eye Health

Hello, S： Currently, the central 30 degrees should be used as a reference for visual field defects, which are not easily noticeable without examination. <br>Retinal degeneration can lead to visual field loss, typically more severe in areas with light, which will appear clearer. <

Visual impairment

Hello, I saw the standards for visual impairment online, and there are two criteria for mild visual field loss: 1.
For the central 24-degree program on the automated perimetry, an average defect greater than 25 dB (exclusive) is required.
2.
For the central 30-degree program on the automated perimetry, an average defect greater than 10 dB (exclusive) is required.
Which one is correct? Additionally, is a visual field defect of 18.14 dB considered significant? (It seems to meet the criteria for moderate visual impairment: for the central 30-degree program, an average defect greater than 15 dB (exclusive).) Why do I not feel much difference? I do not have glaucoma but have retinopathy of prematurity; why do I have visual field loss? If the visual field loss meets the criteria for moderate visual impairment but the visual acuity is within the mild impairment range, what level of disability certificate might I receive? Also, at night in areas with some streetlights, I feel that the lit areas are very bright and clear, while the dim areas are dark and unclear, resulting in an overall perception of some areas being clear and others unclear.
What could be the reason for this? When the lights are off, I see many tiny points of light; is this floaters? (I usually have floaters.) Sometimes when looking at things, I feel the light flickering slightly, or the text appears to wobble a bit; is this caused by nystagmus? (The nystagmus is quite severe.) Is there a significant difference between visual acuity of 0.4 and 0.3? I used to be able to see 0.4 with difficulty, but I don't know when I completely lost the ability to see 0.4 and can only see 0.3 (and aside from the severe nystagmus, there have been no significant changes in the fundus or other examinations).
Can the worsening of nystagmus lead to decreased visual acuity, or does decreased visual acuity cause the nystagmus to worsen? If I can see more clearly when my eyes turn inward slightly, but I cannot see clearly when they turn inward more or outward, what could be the possible reasons? During fundus photography, the optometrist kept saying that my eyes were not aligned with the green dot, but I felt I was aligned.
He asked me to turn my eyes inward a bit more, so I tried, but it felt very difficult to align with the point I needed to see; what could be the reason for this? After turning my eyes inward for a while, I feel soreness on the outer side of my eyes, or the entire eye feels sore; is this due to fatigue? Previously, at the hospital, the optometrist used a long, pen-like instrument to measure intraocular pressure, with readings of 50 and 56 in the left eye (with corneal opacities) and 31 and 36 in the right eye.
I was very nervous during the multiple measurements, and although the optometrist took two readings, the doctor did not mention intraocular pressure at all.
Should I be concerned? In the fundus photography, the right eye shows the area of surgery for retinopathy of prematurity and a scar, which seems to cause the blood vessels to appear somewhat dilated.
The left eye could not be photographed due to corneal opacities, but the optic nerve appears normal.
What does this indicate? Thank you.

S, 10~19 year old female. Ask Date: 2022/04/10

Dr. Gao Pilin reply Ophthalmology

Hello, S: Currently, the central 30 degrees should be used as a reference for visual field defects, which are not easily noticeable without examination.
Retinal degeneration can lead to visual field loss, typically more severe in areas with light, which will appear clearer.
When the lights are turned off, you may perceive many small points of light, which is different from floaters and could be a form of photopsia.
Nystagmus can cause objects to appear to shake, and it can also impair vision.
Poor visual clarity during visual development can contribute to nystagmus.
A visual acuity of 0.4 is better than 0.3, but it's difficult to determine how significant the difference is.
At a certain angle, the nystagmus may decrease, or the image may fall on a better area of the retina, resulting in clearer vision.
Since you are not looking directly at the fovea, the alignment may be off, making it difficult to focus on the desired point.
The discomfort you feel is likely due to fatigue.
Hand-held devices can sometimes be inaccurate, and the measurements taken by the physician may not be high.
This indicates retinal changes associated with retinopathy of prematurity, while the appearance of the optic nerve is normal.

Reply Date: 2022/04/10

More Info

Understanding visual impairment and eye health is crucial, especially for individuals with a history of eye conditions or those experiencing symptoms that may indicate underlying issues. Your questions touch on various aspects of eye health, including visual field loss, the impact of conditions like retinopathy of prematurity, and the implications of eye pressure readings. Let’s address your concerns systematically.

Visual Field Testing and Standards
1. Visual Field Standards: The definitions of visual impairment can vary, but generally, the criteria you mentioned regarding visual field loss are accurate. The two tests you referenced (the 24-degree and 30-degree automated perimetry) are standard methods for assessing visual field loss. If your average defect is greater than 25 dB in the 24-degree test or greater than 10 dB in the 30-degree test, it indicates significant visual field loss.
2. Understanding dB Loss: A visual field loss of 18.14 dB is indeed significant and may suggest moderate visual impairment, especially if it aligns with the criteria for moderate visual disability. The fact that you do not feel any symptoms could be due to the brain compensating for the loss or the specific areas of the visual field that are affected.

Causes of Visual Field Loss
3. Retinopathy of Prematurity (ROP): This condition can lead to various visual impairments, including visual field loss, due to abnormal blood vessel development in the retina. Even if you do not have glaucoma, ROP can result in scarring and other retinal changes that affect vision.

4. Discrepancy Between Visual Acuity and Field Loss: It is possible to have a significant visual field loss while maintaining relatively good visual acuity. This is because visual acuity measures clarity of vision at a specific point, while visual field tests assess peripheral vision and overall field integrity.

Disability Certification
5. Disability Certification: If your visual field loss meets the criteria for moderate visual impairment but your visual acuity remains in the mild range, you may still qualify for a disability certificate, depending on local regulations and assessments by medical professionals. The specific classification can vary based on the severity of the visual field loss and its impact on daily functioning.

Night Vision and Light Sensitivity
6. Night Vision Issues: The phenomenon of seeing bright areas where there are streetlights and dark areas where there are none could be related to how your eyes adapt to different lighting conditions. This is a common issue in individuals with certain types of retinal damage or conditions affecting the photoreceptors.

7. Seeing Light Spots: The small light spots you see when the lights are off could indeed be related to your existing floaters (myodesopsia). These are generally benign but can be more noticeable in low-light conditions.

Visual Disturbances and Eye Movement
8. Visual Fluctuations: The sensation of seeing slight flickers or movements in your vision could be related to nystagmus (involuntary eye movement), which can be exacerbated by fatigue or stress. If your vision improves when you turn your eyes inward, it might indicate a need for corrective lenses or adjustments in your visual habits.

9. Eye Strain and Pain: Experiencing discomfort or pain after focusing your eyes in a certain position is likely due to eye strain. This is common, especially if you are trying to compensate for visual deficits or if your eye muscles are overworked.

Eye Pressure Concerns
10. Eye Pressure Readings: The eye pressure readings you mentioned (50, 56 in one eye and 31, 36 in the other) are concerning, particularly the elevated readings. High eye pressure can be a risk factor for glaucoma, and it’s essential to follow up with your eye care provider for further evaluation and management.

Conclusion
In summary, your visual health concerns are multifaceted and warrant thorough evaluation by an eye care professional. Regular follow-ups, comprehensive eye exams, and possibly visual field testing will help monitor your condition. It’s essential to communicate all your symptoms and concerns with your ophthalmologist, who can provide tailored advice and treatment options based on your specific situation. Maintaining eye health is crucial, especially with a history of conditions like ROP, and proactive management can help preserve your vision.

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