Glaucoma: Key Questions and Insights for Patients

Q: Glaucoma: Key Questions and Insights for Patients

Hello, Ah Hou： 1. I have not used this type of visual field instrument, so I am unsure if it can correct astigmatism. However, mild astigmatism may not require correction. 2. Unless the pupil is very small, it generally does not significantly affect the visual f

Glaucoma issues?

1.
If a person has over 200 degrees of myopia and astigmatism, will the visual field testing instrument, which corrects refractive errors, adjust for astigmatism in addition to myopia? Does the existing astigmatism affect the visual field test results?
2.
Since pupil size can influence the visual field range, would using a dilating eye drop that solely enlarges the pupil without causing near vision blurriness yield more accurate results in a visual field test?
3.
With a long-term intraocular pressure (IOP) consistently above 21, around 23 to 25, and a cup-to-disc (C/D) ratio greater than 0.7, while the optic disc appearance has not significantly changed over one and three-quarters years, an ophthalmologist mentioned that my optic disc is naturally larger than average.
After monitoring for over a year and a half, both OCT and visual field tests remain relatively normal.
Does this situation indicate glaucoma?
4.
Recently, I measured my corneal hysteresis using the ORA device, and the data is as follows: IOPgg: Left: 18.0, Right: 19.3; IOPcc: Left: 14.4, Right: 11.6; CH: Left: 13.8, Right: 17.5; CRF: Left: 14.0, Right: 17.6; WS: Left: 3.5, Right: 3.5.

a.
Should I consider IOPgg or IOPcc as a more accurate reflection of true intraocular pressure? (Is the standard range for IOP still 10-20?) What do IOPgg and IOPcc signify?
b.
What does WS refer to? (My corneal thickness is 590 micrometers, and previous measurements with a corrected non-contact tonometer still indicated elevated pressures of 23 in both eyes.)
5.
Besides glaucoma, are there other factors that could cause abnormal visual field results? Could fatigue be one of them?
6.
What is the approximate percentage of individuals with ocular hypertension who never require medication throughout their lives without any issues?
7.
While the cup diameter may increase with glaucoma, is the disc diameter generally fixed from birth to death? What factors could potentially cause the disc diameter to increase or decrease?
8.
If someone has ocular hypertension and does not require medication, how many years of monitoring are necessary to confidently determine that it is not glaucoma before discontinuing follow-up? I apologize for the numerous questions, and I greatly appreciate your assistance.

A-Hou, 30~39 year old female. Ask Date: 2020/11/16

Dr. Gao Pilin reply Ophthalmology

Hello, Ah Hou:
1.
I have not used this type of visual field instrument, so I am unsure if it can correct astigmatism.
However, mild astigmatism may not require correction.
2.
Unless the pupil is very small, it generally does not significantly affect the visual field and can be overlooked.
3.
It is still important to monitor changes in the optic disc and visual field to understand any developments.
4.
I have not used this type of device, so it may be best to consult the examining physician.
I apologize for that.
5.
Fatigue will not affect it; any issues with the retina, optic nerve, or the visual pathways to the brain can potentially impact the visual field.
6.
It is necessary to first determine the cause of elevated intraocular pressure; if needed, treatment should be initiated, but if not necessary, it can be avoided.
I apologize for not having conducted such statistics.
7.
Possible reasons for enlargement include myopia, retinal vascular diseases, high intraocular pressure, age, etc.
8.
Long-term follow-up may be required, and based on symptoms, the intervals can be extended.
Normal individuals also need to have their intraocular pressure checked regularly, as no one knows when it might increase.
The Ophthalmology Department at Puzi Hospital in Taiwan is open:
Monday, Tuesday, Thursday, and Friday from 8:00 AM to 12:00 PM
Wednesday from 2:00 PM to 4:30 PM
Online responses can only serve as a reference; if necessary, it is still important to seek medical care at a healthcare facility.
I hope to have the opportunity to serve you.
Gao Pi-Lin

Reply Date: 2020/11/16

More Info

Understanding glaucoma is crucial for patients, especially those with risk factors such as high myopia and astigmatism. Here are detailed answers to your questions based on current medical knowledge.

1. Visual Field Testing and Astigmatism: When performing visual field tests, the equipment is typically calibrated for the patient's refractive error, which includes both myopia (nearsightedness) and astigmatism. If you have astigmatism and do not wear corrective lenses during the test, it may affect the accuracy of the results. Astigmatism can distort vision, potentially leading to inaccuracies in the visual field assessment. Therefore, it is advisable to wear corrective lenses during the test to ensure the most accurate results.

2. Pupil Dilation and Visual Field Testing: Pupil size can indeed affect the visual field range. Using a dilating agent that does not cause near vision blurriness can be beneficial for visual field testing. This allows for a more comprehensive assessment of peripheral vision without the interference of near vision issues. However, the choice of dilating drops should be discussed with your eye care provider to ensure they are appropriate for your specific situation.

3. High Intraocular Pressure (IOP) and C/D Ratio: Having a consistently elevated IOP (above 21 mmHg) and a cup-to-disc (C/D) ratio greater than 0.7 raises concerns about glaucoma. However, if your optic nerve head (the "disc") has been stable over time and your OCT (Optical Coherence Tomography) and visual field tests remain normal, it may suggest that you do not have glaucoma at this time. The statement from your ophthalmologist about your optic nerve being "naturally larger" is important, as some individuals have larger optic nerves without having glaucoma. Continuous monitoring is essential, especially given your risk factors.

4. IOP Measurements: The IOPgg (Goldmann-correlated IOP) and IOPcc (corneal-compensated IOP) provide different insights into intraocular pressure. IOPcc is generally considered to give a more accurate reflection of the true IOP, especially in patients with corneal thickness variations. The normal range for IOP is typically between 10-21 mmHg, but this can vary based on individual circumstances. The WS (Waveform Score) is a measure of the variability of the IOP readings; a lower score may indicate less stability in the IOP.

5. Factors Affecting Visual Field: Abnormal visual field results can be caused by various factors beyond glaucoma, including neurological conditions, retinal diseases, and even fatigue. Stress and fatigue can temporarily affect visual performance, but persistent issues should be evaluated by an eye care professional.

6. High IOP Without Treatment: The proportion of individuals with high IOP who do not develop glaucoma varies. Some studies suggest that a significant percentage of patients with elevated IOP may remain stable without treatment, but this is not guaranteed. Regular monitoring is essential to catch any changes early.

7. Optic Nerve Head Size: The size of the optic nerve head (the "disc") can change over time due to various factors, including age, disease progression, and individual anatomical variations. While the overall structure may remain relatively stable, changes can occur, particularly in response to conditions like glaucoma.

8. Monitoring High IOP: If you have high IOP without treatment, the duration for which you can safely avoid monitoring varies. Generally, regular follow-ups every 6 to 12 months are recommended to ensure that no changes occur that would indicate the onset of glaucoma. If there are no changes over several years, your eye care provider may discuss the possibility of less frequent monitoring.

In summary, understanding your eye health, especially regarding glaucoma, is vital. Regular check-ups, wearing corrective lenses during tests, and discussing any concerns with your eye care provider will help manage your risk effectively. Always consult with your ophthalmologist for personalized advice tailored to your specific condition.

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