Astigmatism and cataract surgery

[mujieye]

Does cataract surgery itself lead to worsening astigmatism? How much astigmatism in D can meaningfully impact vision / refractive outcome after cataract surgery granted there are no macular or retinal issues and IOL placement looks fine?

[John C Hagan III, MD, FACS, FAAO]

I am referring to modern, small incision (about 4-5 mm), no-stitch surgery where the incision is place at the lateral 3 or 9 o'clock meridian on the cornea.    Such an incision may reduce  "against the rule' astigmatism  about 0.25-0.50 diopter or increase "with the rule astigmatism" by a like amount.    There is no formula to calculate visual acuity without glasses in an otherwise normal eye with regular corneal astigmatism.  

[mujieye]

Thanks Dr. Hagan. Is 0.75 D astigmatism significant enough to induce blurry vision after cataract surgery (distance vision) ?  Can post-op astigmatism improve over time?

[John C Hagan III, MD, FACS, FAAO]

A glasses RX has  3 components    sphere   cylinder and axis     So it is not possible to answer your question.   If the eye is healing normally and the distance RX is 0.0 + 0.75  X   ? axis   then vision at 20 ft (6 m) should be good (20/25 or better) however the near vision would be blurred and require reading RX.   On the other hand if the RX is -3.00 + 0.75 X ? axis then the distance vision will be very bad but vision at 18 inches without glasses would be good.   So the "spherical power' is very important in addition to the astigmatism.

[John C Hagan III, MD, FACS, FAAO]

As to your question.  Because the incision is small and no stitch usually used Astigmatism does not usually change much in the years after cataract surgery (generally less than 0.50 diopter).  

[mujieye]

I should have specified spherical value  is -0.5.

[John C Hagan III, MD, FACS, FAAO]

So a glasses RX of     -0.50 sphere plus/or/minus 0.75 at any axis in a normal eye, or a eye post op cataract/IOL that has no other problems and is healing well should have about 20/25+ uncorrected vision at distance (20 feet)

[mujieye]

Thanks Dr. Hagan. I am seeing 20/40  uncorrected but the rx does correct me to 20/20; unsure why I am not close to 20/25.   I am being told that I might need lasik in a few months.

[John C Hagan III, MD, FACS, FAAO]

How long ago was your surgery?

[mujieye]

Surgery was 2 weeks ago.  Since my other eye is blurry at distance, I am currently quite uncomfortable with my vision overall as even the 20/40 VA is not crisp. Do you think there is a chance my vision might improve with  time/healing?  If not, is Lasik an option for me with these numbers to be able to achieve close to plano vision and also correct astigmatism on the operated eye? I just don't want to keep doing additional procedures on my eye.

[John C Hagan III, MD, FACS, FAAO]

Assuming the eye looks good to our surgeons and the tests we post operative like macular OCT we tell people not to judge the success of their surgery till at least 4-6 weeks out.   Discuss with your surgeon.  You should be getting near the post (usually post op visit #3) where an end point refraction is done.    Your eye should be correctable to 20/20 with a glasses refraction that includes any residual astigmatism and plus/minus sphere.  The problem is if a refraction does NOT correct to 20/20 then the cause needs to be determined.

[mujieye]

I plan to discuss next steps at my next appointment.
While I am awaiting my apt, I am reading about PRK and LASIK and I am scared to undergo either of these procedures given risks of corneal ectasia. Is LRI a better option for me for astigmatism correction?

[John C Hagan III, MD, FACS, FAAO]

I think you are missing the point and jumping the gun.  You don't have a lot of astigmatism. The problem as you presented to me is NOT that you have 0.75 diopters of astigmatism it is that when your glasses correction is put in front of your eye you do not see 20/20 and have no explanation for this.