Glaucoma: Key Questions and Treatment Considerations - Ophthalmology

Regarding glaucoma issues?

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Thank you again for your guidance on the eye drop issue during my last visit.
I would like to seek your advice on the following matters:
My husband, aged 44, had his intraocular pressure (IOP) checked on February 2, 2009 (left eye 27 mmHg, right eye 28 mmHg).
An OCT (Optical Coherence Tomography) examination for glaucoma indicated that the thickness of the optic nerve was somewhat reduced (average thickness: right eye 86.15 µm, left eye 93.35 µm).
Both eyes showed thinning in the inferior region according to the OCT report, falling within the "red" range.
The right eye also showed a "yellow" range in the nasal region.
The visual field test indicated that the right eye's GHT was outside normal limits (MD: +0.28 dB, PSD: 2.71 dB, P <10%), but it would not currently affect daily vision.
The left eye's GHT was within normal limits (MD: +0.68 dB, PSD: 1.79 dB).
The doctor diagnosed it as early-stage chronic open-angle glaucoma.
He started my husband on timolol Chauvin 0.50% eye drops on February 21, 2009, to be administered twice daily.
At the follow-up appointment three weeks later (March 14, 2009), the IOP was measured (left eye 19 mmHg, right eye 20 mmHg), and again two months later (May 7, 2009), the IOP was (left eye 20 mmHg, right eye 21 mmHg).
The doctor advised continuing the same eye drops (twice daily) and to perform another OCT and visual field test three months later (around August), with a possibility of switching to Xalacom - latanoprost & Timolol eye drops.
1) I previously asked my husband's doctor about the suitability of laser surgery in the future, and he mentioned that traditional surgery would be necessary if surgery is required.
I would like to understand under what circumstances chronic open-angle glaucoma typically necessitates surgery.
Is it dependent on the following conditions:
- Intraocular pressure not improving with various eye drops?
- What are the specific IOP thresholds? (Please provide details)
- What level of PSD loss in the visual field test is concerning? (Please provide details)
- What degree of visual field narrowing is significant? (Please provide details)
- At what level of optic nerve cupping (is it above 0.7-0.8 that surgery is considered?) - (Please provide details)
- What thickness of the optic nerve in the OCT examination warrants consideration for surgery? (Is there a specific average thickness number to consider? Please provide reference numbers.)
- Does the optic nerve's curve in the OCT examination need to fall into the yellow or red range in all four quadrants (superior, nasal, inferior, temporal) to consider surgery?

I understand that answering these questions may be complex, but I would like to grasp some concepts to assess the necessity of surgery.
I kindly request your professional analysis for reference.
Thank you.
2) Regarding glaucoma treatment, is there a six-month timeframe to determine whether to add or switch eye drops? If the IOP is stable, does the efficacy of each eye drop typically last about six months? How long can it actually last? If the IOP is not ideal, can we add or switch eye drops during this six-month period (for example, in the fourth month)? However, do we need to perform OCT and visual field tests before adding or switching eye drops, even if it is before the sixth month?
3) I have heard that glaucoma patients should avoid mydriatics.
If the IOP has dropped below 21 mmHg, should glaucoma patients still minimize the use of mydriatics? If mydriatics are necessary, how much can they raise the IOP? How many days should be allowed between mydriatic uses for eye examinations?
4) The doctor previously mentioned: “The optic nerve can tolerate some minor changes, but if the IOP fluctuates too much or is too unstable, the optic nerve may struggle to cope.” However, I do not understand how the IOP can still fluctuate significantly or be unstable when the patient is already using eye drops to lower it.
What does the doctor mean by IOP fluctuations? Is it due to forgetting to use the eye drops? Or switching to another eye drop? Or is it when the effectiveness of the eye drops begins to wane? Please provide clarification.
5) Could you provide examples of significant or unstable IOP fluctuations in terms of degree and timing?
6) I have heard that some eye drops not only lower IOP but also increase the perfusion pressure of the optic nerve, providing neuroprotective effects or enhancing blood circulation.
Does Xalacom - latanoprost & Timolol have these functions? Could you provide the names of other eye drops with similar functions for reference?
7) When switching from timolol Chauvin 0.50% eye drops to Xalacom - latanoprost & Timolol, the doctor mentioned that the efficacy of Xalacom would take about two weeks to manifest.
During this two-week transition period, since Xalacom's effect has not yet fully developed, but timolol Chauvin 0.50% is being discontinued, will the IOP rise during this period? Could this potentially lead to optic nerve damage due to the inability to tolerate increased pressure? Thank you for your explanation.
8) Does drinking a cup of coffee and green tea daily raise IOP? I apologize for the numerous questions, but I kindly request your responses to these eight inquiries for valuable reference.
I greatly appreciate your assistance.
Wishing you a pleasant day! Thank you.

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Tim Tim, 40~49 year old female. Ask Date: 2009/05/18