Accomodation question

[UWStudent]

hi Everyone,
I have a question about accomodation.
Hope someone can help me. thanks


R: -2.00DS
L: -5.00/-500x180 Add: +2.00DS BE. WD: 50cm.

Question:
1) Which eye accommodate more, in distance or near?

2) Which visual direction where the eye accommodate most: Looking from Left to Right or Looking from top to bottom?

---

Members don't see this ad.

 

[20DOC20]

The accommodative demand at optical infinity is zero. The accommodative demand is 2 D for 50 cm WD. The demand is a constant in both cases.

I feel like question one is missing a variable and that it's a poorly written question.

For question one, I would say neither eye accommodates more in distance because each eye is myopic and the demand is zero. There is no negative accommodation. The refractive error in this case is irrelevant because the patient is myopic.

However, if the patient were hyperopic and UNcorrected, say, +2.00 OU and the accommodative demand is zero the patient's accommodation at distance to attain clarity is 2D. So if you gave the patient a correction of +2.00, the lens correction should theoretically bring distance accommodation back to zero.

If you overminused the patient in question one by 2D you'd have CORRECTED accommodation at infinity of 2D, essentially making them +2 and very angry at you.

For near, 2D is the demand. UNcorrected the right eye has 2 diopters of demand taken up by the refraction and the near rx is plano thru the add. Therefore there is no accommodation. The left eye spherical equivalent is -7.50D and again 2D are taken up by the ADD leaving -4.50D total power thru add. But, the focal point on that eye is closer than the demand and blur is caused by needing negative accommodation to focus, or bring object closer. Is neither a choice? If one eye were -1.00 and the other spe of -2.50 I'd day the -1.00 D eye had to accommodate more. But given that the answer requires negative accommodation, which is to be ignored, and the other none, I really don't no how to answer it.

You worry about negative accommodation in terms of relativity. Negative relative accommodation. Positive relative accommodation, with the constant in both cases being measured around a working distance.

Maybe I'm having a senior moment.

Question two I'd say you accommodate more vertically, top to bottom. Because of the ACA phenomenon and vergence you accommodate more easily in the downgaze position, just because of wiring.

EDITED on 8/7/13

 

[20DOC20]

Note: error fixed with edit. (was thinking in + cyl). Still thinking about question and it's inpertinent. There's not enough info to really answer it because there's no context. Is this a physiological optics class or a behavioral optometry class? A behavioral optometrist would say the eye with most cyl would accommodate more in either case, but a physiological optics teacher would say the numbers zero out.

 

[UWStudent]

Thanks for your response. Yes it is a really tough question I am struggling with myself. Any other users out there that can contribute to the discussion and answer the two questions.. Greatly appreciate all of your help. Cheers

 

[KHE]

hi Everyone,
I have a question about accomodation.
Hope someone can help me. thanks


R: -2.00DS
L: -5.00/-500x180 Add: +2.00DS BE. WD: 50cm.

Question:
1) Which eye accommodate more, in distance or near?

2) Which visual direction where the eye accommodate most: Looking from Left to Right or Looking from top to bottom?

This is a very poorly worded question that seems to be missing some information but I'll take a stab at it.

In the left eye, the power is -10.00 in the vertical meridian so the stimulus to accommodation would be the most in the vertical direction.

 

[Commando303]

hi Everyone,
I have a question about accomodation.
Hope someone can help me. thanks


R: -2.00DS
L: -5.00/-500x180 Add: +2.00DS BE. WD: 50cm.

Question:
1) Which eye accommodate more, in distance or near?

2) Which visual direction where the eye accommodate most: Looking from Left to Right or Looking from top to bottom?

As others have said, your question is very poorly worded, even from a grammar standpoint. Is this a verbatim reproduction from a classroom exam?

I imagine the problem wants to know about effectivity. If this is the case, I'm pretty sure the left eye will accommodate less, and it will accommodate least in the 90th meridian. (To be certain, the numbers can be run through the vergence equation: V = n / r.)