I think it is a routine practice that we measure distance IPD and calculate it for near based on distance IPD. I never had issues with this.......Ideally near IPD should be measures but it rarely done in practice. If you are seeing a lot of patients with visual complaints after such procedures, you are calling for an important research question that can be investigated for more insights....

What do you need near IPD for? For centering reasons in spectacles it is agreed (and there is clinical evidence) that you can fit single vision near lenses with far IPD (except for some binocular disorders). For aspheric lenses you must do it this way, otherwise you will get a lot of aberrations. If visual complaints occur you should check far IPD for accuranteness and even more important vertical centering of the glasses. Multifocals need to be fitted with far IPD anyway.

i think IPD measurement by a meter rule or a pupillometer is better,most times autoret shows accurate measurements,after you can still evaluate with your trial frame,by setting the pointer to the actual figure you got in autoret. is expected that after retraction,the patient needs to walk with it .when the actual frame that fits the patients face is in place,most time IPD causes no problems. most importantly the centering of the lens during chipping and fitting of lens is paramount,because if one of the pair of lenses is not centered well,it definitely affects the second pair.

Yes, I encourage routine measurement of IPD because many times, I see a discrepancy with the Autorefractor measurements.

Yes, I encourage measurement of IPD with Pupillometer/PD ruler because there are discrepancies with the Autorefractor measurements especially when the patient doesn't rest the chin and/or head appropriately. And sometimes I find that Pupillometer readings are not also accurate especially for very high or very small measurements. I have found some papers which support this observation. So, I prefer to measure the IPD with a PD-ruler which is most accurate.

i don't encourage practitioners to depend solely on autoret in routine measurement of IPD, because it produces 50% inaccurate figures. mostly the figures gotten with autoret are lesser. i think is best after testing the eye with autoret,is good to confirm the IPD with meter rule or pupillometer before fitting the glasses. generally the way we confirm by doing subjective refraction after autorefraction, should also be the same way we confirm with meter rule or pupillometer.

Measurement of IPD is well agreed to be useful in proper centering of spectacle lenses in both single vision and multifocal lenses. Its also being used in diagnosis of certain syndromes as well. As for Hans-Juergen Grein's question on what do you need near PD for, we recently carried out a study that showed that inaccaracies exists in extimating NIPD of px from measurements obtained for FIPD. This is even moreso in high prescription lenses, multifocals, and in situations of binocular anomalies where prisms may be needed either in a grounded form or by decentration. Its been suggested by various studies that measurement of both FIPD and NIPD be taken in such pxs outlined above. In addition, the difference between FIPD and NIPD irrespective of what technique was used to obtain them also varies with the population. I guess we have to begin considreing both measurements.

Estimation of IPD with a PD rule is good enough as its inexpensive and can be recommended for a day-to-day practice. I agree with one of the above statements that an error in automated equipment might give us inaccurate results and might not be reliable all the time.

I am a stickler for getting accurate "monocular PD's" no matter where I am seeing patients {I have a locum tenens practice and have served many offices in Georgia USA the past 12 years}.I actually carry a pupillometer with me in case the office in which I am serving does not have one and specify the PD's myself as I write the spectacle Rx.

An autorefractor PD is "out of the question" , useless except for possible comparison as to total PD ; and that does not account for possible convergence possibilities during the testing. Nor does it account for anatomic variance of eye location .

Luxottica which owns Lenscrafters and other ophtlalmic chains has perhaps the best device that their opticians use as they get such measurements on a TV monitor ,sharing the images with the patient. I think that similar devices are being marketed to the mass ophthalmic market .

BILL SHARPTON,O.D.,F.A.A.O.

Lakemont, Georgia USA

I agree that IPD (inter pupillary distance) should be measure in each patient and it is mandatory for satisfactory performance of spectacles; as centration is important both in monfocal and multifocal spectacles. IPD is measured using Pupillometer /PD ruler. As a Ophthalmic surgeon, it is must to adjust IPD accurately for comfortable visualization while performing surgery and this is equally true to provide accurate IPD by measuring both for monofocal or multifocal spectacles.

I measure the near IPD by asking the patient to look at a light source held at 40 cm. I then add 4 mm to to get the far IPD. I never rely on the autoref because it usually gives inaccurate measurements. I close one eye when taking these measurements to avoid parallax

Accurate IPD measurement is mandatory and I would prefer pupillometer, but using a PD ruler is a more practical approach due to its universal availability.

IPD is really important and we use to do it very carefully because in multifocal lenses adaptation, one millimeter makes a huge difference. I have used the ruler by 10 ten years and it seems it works perfectly. We are used to add add 2 mm to the measure distance taken for near IPD.

We use a pupillometer or PD rule and do not rely on the value obtained from the auto refractor.

Ayman Alkawas adds 4mm to the NIPD to get FIPD; Andrea Perez adds 2 mm to NIPD to get FIPD. This is where the controversy stems deep. With very aspheric prescriptions, multifocals or even in terms of surgery or to aid diagnosis of certain anomalies, the difference from both of the suggested literary additions you have made is significant. Do you not think, we will be better of if we measures both FIPD and NIPD in every px, especially those listed above?

I encourage routine measurement of interpupillary distance (IPD) by a meter rule

I use PD rule for measurement of interpupillary distance (IPD) and it is more practical and accurate.

I like to check the autorefractometer result, by measuring the IPD for near also. In cases with strabismus, I think it is a must to measure the separate monocular distance

I prefer using a PD ruler. The use of multifocals require more precise measurement. However, both ends of the age (children and older adults) spectrum have unique needs and more precise measurement is important.

I have found in many bifocal lens the centers of the lens particularly for distant lens could not be detected and they burried in the near lens.