Question of the Week

A 70-year-old man presents to your clinic for his 1-month post op appointment following cataract extraction of the right eye. He has no history of corneal or retinal pathologies, and this is his only ocular surgery. His preoperative BCVA was 20/40 with a refraction of -2.50 +0.50 at 90º in the right eye. The surgery was uncomplicated, and a 3-piece-IOL was implanted in the capsular bag (IOL schematic in Figure B) with a target of plano for distance vision. Post op day 1 uncorrected visual acuity was 20/70 with 2+ cornea edema. Today, at the post op month 1 visit, the cornea edema is completely resolved, and uncorrected visual acuity has improved to 20/40. You make the following finding at the slit lamp exam when performing a dilated exam (Figure A):

Based on the information that you have, make a prediction about this patient’s remaining refractive error in the right eye:

A. Myopic

B. Hyperopic

C. Plano; expect visual acuity to improve following YAG capsulotomy

D. Impossible to predict

Answer

The correct answer is A

The correct answer to this question is A. The main finding to recognize in figure A is that the lens was inadvertently implanted upside down in the capsular bag, which was not noticed at the time of surgery. You can recognize this error in a patient who is well dilated with the haptics visible at the slit lamp. Here, the haptics are in an “S” configuration, when they should be properly positioned in an “anti-S” configuration or with the leading haptic shaped like a “7” and the trailing haptic shaped like the capital letter “L”. Although inverting the lens may not always be a problem, in lenses that have vaulted haptics, such as in this 3-piece MA60AC lens, there is a 10º angulation of the haptics away from the optic plane. When implanted in the proper configuration, this means that the lens will be positioned posterior to the tips of the haptics (See figure B). However, if the lens is inserted upside down, the effective lens position will move anteriorly, resulting in a myopic shift. Therefore, choice A is the best answer because there are no other pathologies visible on the slit lamp to explain why the visual acuity is not 20/20. Given the anterior position of this lens, this patient may also be at risk of pupillary block or iris chafing. The decision to replace/reposition this lens or to leave it in place while correcting the remaining refractive error with glasses rests with the surgeon and the patient. Not all IOLs have a vaulted optic, so reversing the lens configuration may not be a significant problem in all patients. However, other lenses, in particular EDOF lenses, may have asymmetry in the refractive power between the anterior and posterior surfaces of the IOL.

Source:https://www.nature.com/articles/6702496, https://cataractcoach.com/2022/12/08/1676-this-iol-is-going-in-upside-down/