Dear Doctor Hagan,
Thanks again for your answer. It was very helpfull.
Kind Regards,
AlexN
I believe you are grossly over estimating the value and reproducibility of there measurements of the C/D ration and Cup volume. They have too much variablity to treat them like measuring time with an atomic clock. If one person does the test on another person then waits 5 minutes and repeats the test there can be a 15% variance.
The PUFF tonometer is not as accurate as the goldman tonometer.
I believe the advice you have been give is appropriate given the data I have to look at.
If you are going to fret this much you might want to get a second consult from a glaucoma specialist.
It is extremely unlikely that any systemic disease is causing variability in the testing.
JCH MD
Dear Doctor Hagan,
Regarding my issues with HRT, I've done some more investigations and perform an OCT in order to answer to my questions. Unfortunately the situation seems to be more foggier then it was.
After going through the results I have the following issues/questions:
1. Seems to be a difference between HRT and OCT. I've heard that OCT is more precise then HRT and that OCT is over evaluating the C:D ratio but still the true value is more close to OCT. Any input on this?
2. Asking my doctor about my OS HRT C:D ratio progression with 13% in 13 months he said that if C:D ratio could be accurately measured then 13% is too much but considering the difficulty in measuring the C:D ratio and the human HRT operator involvement the 13% increase in C:D ratio could mean nothing(can just be an HRT operator issue). Being an engineer with a very technical background is very hard for me to accept this argumentation. Any input on this?
3. Is there a different formula for C:D ratio between HRT and OCT?
For instance in my HRT measurement I see the following:
OS: Disc Area = 2.01; Rim area = 1.08; Cup area= 0.93; Cup/disc area ratio = 0.46
So:
- DiscArea=RimArea + CupArea => 2.01 = 1.08 + 0.93 TRUE
- C:D ratio = 0.93/2.01 = 0.46 which is the same with the one in the HRT results page
Now, for the OCT seems that there is another formula for C:D ratio.
So, in my OCT results page I have the following for OS:
OS: Disc Area = 1.96; Rim Area= 1.10; Cup area is not presented; Cup/disc ratio = 0.65
So:
- DiscArea = RimArea + CupArea => 1.96 = 1.10 + CupArea => CupArea=0.86
- C:D Ratio = 0.86/1.96 = 0.43 which is different then the C:D ratio = 0.65 from the OCT results page => that there is different formula for C:D ratio between HRT and OCT
I see the same difference in the C:D ratio formula for the other eye.
Then which are the normal values for HRT and OCT?
I see that for the HRT the normal maximum value for C:D ratio is 0.3. For OCT I just see that for my OD C:D ratio of 0.57 is marked with green and the OS C:D ratio of 0.65 is marked with yellow. So I suppose that anything above 0.59 is abnormal?!
4. Regarding the progression of my OS C:D ratio what is the value of having recorded pictures of the optical nerv when there is this chance of operator error?! I was trying to compare HRT against OCT to get a pattern. I've noticed that using the OCT C:D ratio formula the C:D values are bigger with 0.2 then this year HRT C:D values for both eyes. The getting the C:D ratio using the HRT formula on OCT measurements the C:D ratio obtained is with 0.03 smaller then the HRT C:D ratio for both eyes. This pattern somehow validates the HRT measures for this year because they are the same for both eyes. So, can I conclude that my OS C:D ratio has increased with 13% in 13 months?! This year HRT measurements seems to correspond with the OCT measurements but what about last year? What if there was a human error for my first left eye HRT measurement?
To conclude, I think that the C:D progress can only be assess when 2 or more different devices are used in the same period in different years to measure the optic nerve.
5. Another strange thing that happens to me is that my Goldman tonometry is much too low then puff tonometry having a corneal thickness of 570. All my Goldman readings are below 20 mm Hg and all my "puff" readings are above 25 mm Hg. I was using different Goldman devices and different puff devices in order to avoid devices issues or calibration issues. The same pattern was encountered.
6. The doctor said that because there is no visual field loss, because the RNFL thickness is within normal limits and the Goldman readings are normal, for the moment no treatment, come back in 1 year for HRT and OCT measurements. From 3 to 3 months perform Goldman readings and fundus exams. Get 1 day hospitalization for frequent monitoring the IOP and solving the Goldman vs "puff" big difference mistery. Any input regarding my diagnostic approach? Do you think that is safe to wait for 1 year regarding my previous year OS C:D ratio progression (if any?) ?
7. I am somehow worried that it might be another illness that is causing my C:D ratio progression in my left eye and that I've only escalate this to the ophthalmologists. On the other hand I think that the 3 ophthalmologists that have seen me would have redirect me to another specialist if the case.
Sorry for the size of the message but I am just trying to clarify some aspects that are quite hard to clarify with my doctores.
Thanks again for your valuable time,
AlexN
Dear Doctor Hagan,
I live in Romania, Bucharest and my insurance is covering this. My doctor informed me that the 24 hours - hour by hour check could not reflect what is really happening, but she said that whants to do so because maybe she could catch a fluctuation or something. She said that ussualy during hospitalization the IOP should be bigger due to lack of physical activity, being in bad and anxiety related to hospitalization. So 1 day IOP measurement she said that for some cases represents the worst case situation, for others no.
More then that, she also recomended me to measure the IOP every month. I've asked for self monitoring of IOP, if this can bring value to the diagnostic process and she said that the devices for the self measurement of IOP ar not yet there regarding how precise they are and how safe they are. She's approach is to measure IOP for month to month at different time of the day and also for year to year to perform an one day measurements.
Is there a more performant approach then the one that I'm following?
Thanks again for your answers,
Alex
Dear Doctor Hagan,
I live in Romania, Bucharest and my insurance is covering this. My doctor informed me that the 24 hours - hour by hour check could not reflect what is really happening, but she said that whants to do so because maybe she could catch a fluctuation or something. She said that ussualy during hospitalization the IOP should be bigger due to lack of physical activity, being in bad and anxiety related to hospitalization. So 1 day IOP measurement she said that for some cases represents the worst case situation, for others no.
More then that, she also recomended me to measure the IOP every month. I've asked for self monitoring of IOP, if this can bring value to the diagnostic process and she said that the devices for the self measurement of IOP ar not yet there regarding how precise they are and how safe they are. She's approach is to measure IOP for month to month at different time of the day and also for year to year to perform an one day measurements.
Is there a more performant approach then the one that I'm following?
Thanks again for your answers,
Alex
Where do you live. Being hospitalized for frequent IOP is something most insurance programs would not pay for in the USA (and I agree).
Recent studies indicate that even if your IOP was checked every hour for 24 hours that that may not reflect what happends the next day and the next day. Recent studies indicate that IOP in the eye is not like the tides at the ocean where they can be predicted accurately. Moreover just being in the hospital, inactive, in bed, or being woke up every hour for an IOP may not at all duplicate what your IOP is like at home sleeping undisturbed in your own bed and going about your daily routines.
JCH MD
Dear Doctor Hagan,
Thank you for your fast and detailed reply. I'm really appreciate your presious time for delivering this answer.
I'm less worried now. The next step is to get hostpitalized (as my current doctor sugested) one day for very frequent Goldman eye pressure measurements.Then I'll get the chance to ask her again about the reasoning behing left eye C:D ratio progression according to HRT.
Thank you very very much again,
Alex
General: the "puff" varies way too much from Goldman. Goldman is always more accurate but the puff should be within 1-2 mm of the goldman. The "puff" needs to be sent back to the factor for recalibration. The results are worthless!!
1. Provided you are seeing a competent ophthalmologist I think few people would diagnose glaucoma or put you on meds. (you omit whether there is a family history of glaucoma. I'm assuming there isn't)
2. yes just like the puff air tonometry readings are erroneous.
3. Yes
4. cup to disc ratios and cup volume are notoriously difficulty to accurately determine and even the same observer (optom or Eye MD) have given different numbers when tested on the same subject the same day when identity is covered (intra-oberver error and from one observer to another interobserver error). Your readings are not alarming.
5 optic nerves when measured ultra closely are never the same shape as the other just as ears, arms, legs and other paired organs are never the exact same size, shape and weight.
6. Relax a little. See a good ophthalmologist each year and have at least one special glaucoma test such as nerve fiber layer OCT or visual field. If you have no family history of glaucoma you are at little risk at your young age.
JCH MD
Dear dr. Hagan,
I'm under Glaucoma evaluation for 1.5 years now with still no diagnostic. I'm 29 years old caucasian male.
Those are the characteristics of my eyes:
- physiologic asymetric papils(discs) right disk = 1.57 mm2 , left disk = 2.01 mm2 (measured by HRT)
- Corneal thickness in both eyes = 570 > normal
- IOP measured with "PUFF" devices: allways > 21 mm Hg. Maximum value 31 and 29.
- IOP measured with Goldman allways <=20mm Hg. Average values 16-18 mm Hg.
- After repeting the HRT after 13 months there ware some changes:
- Left eye:
- Rim area decreased with 0.15 mm2 from 1.23 to 1.08 (13%)
- Cup area increased with 0.14 mm2 from 0.79 to 0.93 mm2
- Cup Volume increased with 0.16 mm3 from 0.13mm3 to 0.29 mm3
- Rim Volume increased with 0.01 mm3 from 0.22 to 0.23 mm3
- Cup/Disc Area Ratio increased with 0.07 from 0.39 to 0.46
- Mean RNFL thickness remain constant at 0.16 mm
- Visual Field = PSD= 1.22DB ; MD = -1.27 dB within normal limits
- Right Eye:
- Cup area increased with 0.02 mm2 from 0.56 to 0.58 mm2
- Rim area decreased by 0.02 mm2 from 1.01 to 0.99 mm2
- Cup Volume = constant = 0.14 mm3
- Rim Volume decreased by 0.01 mm3 from 0.25 to 0.24
- Cup/Disc Area ratio increased with 0.01 from 0.36 to 0.37
- Mean RNFL Thickness decreased with 0.01 from 0.26 to 0.25 mm
- Visual Field = PSD= 1.45DB ; MD = -1.57 dB within normal limits
My doctor concluded that for the moment everything is OK (main argument being the RNFL thickness being constant) and no treatment and come back in one year for reevaluation (HRT, visual field). In the meantime measure from 3 to 3 months the IOP using only Goldman, no puff. I will like a seccond opinion mainly beacuse my concerns regarding the C:D ratio in the left eye, asimetry between right and left, cupping progression in left eye.
QUESTIONS:
1. Please provide me with your views regarding my data from above.
2. Can errors occur in HRT measurement?
3. Is safe for me to wait 1 year without treatment for reevaluation?
4. Can there be other disease then glaucoma causing unilateral cupping (neurologic) ? In the pictures my optical nerve seems to be pink, is not swallen or pallor. I do not have headakes or disiness or nausea.
5. I am also concern about the small cupping in the right eye begause it has a smaller disc. Please provide input.
6. What do you advise?
Thanks,
Alex N.
thank you so much, now I'm going to sit back and enjoy
Thanks you so so much
1. Most optic nerves have cupping. As I told you before most nomral optic nerves have about 40% cupping or less. 50-60% is borderline and anthing more is very suggestive of glaucoma.
2. If I were you I would not worry since you have been adequately evaluated and told not to worry now just have regular checks (most common every 6 months)
3. the topic anesthetic will not affect you or the fetus.
JCH MD