Eyeworld

EW NEWS & OPINION 27 "I would like to see more cells on the specular microscopy exam. I would remove and replace with ei- ther a traditional aspheric lens or if the bag looked really good and the patient desired a better range of vi- sion, a Crystalens AO. Also, I would like to know where the astigmatism on manifest came from? Tilted lens since it does not show up on the to- pography." Jeff Whitman, M.D. Others on the "panel" shared similar concerns but were not ready to do a lens exchange based on what was presented here. They felt I needed to "dig a bit deeper." "I am not surprised at all that this patient is not happy for the fol- lowing reasons. He is phakic in one eye with a mild cataract—always dangerous as one's natural lens is a tough compar- ison to a multifocal unless the cataract is relatively dense. He has too much residual refrac- tive error in the left eye in my opin- ion for this to be a successful result. His spherical equivalent is about –0.40, which is not great, and he has too much residual cylinder. I find that people really don't tolerate more than 0.5 D cylinder easily with these lenses. Also, the refraction and the to- pography are not in sync. He has 0.75 D of corneal astigmatism and 1.25 D of refractive cylinder. This does not make obvious sense to me. I could not tell from the slit lamp photo, but I would be con- cerned about some tilt in the IOL even if it grossly appears to be cen- tered in the rhexis. Do we know if there are any problems with the sta- bility of the bag peripherally? I would not yet be in favor of exchanging this lens. What else have you got?" Jeff Horn, M.D. "Some people just don't have good subjective vision with multifo- cal lenses, but you certainly need to rule out other causes of visual loss before attributing the problem to the lens. If his cornea is normal, the lens appears well centered, there is no significant posterior capsular opacity, and the macula is normal on OCT, you have ruled out the ma- jority of the common causes of poor vision after cataract surgery. Color vision testing, a visual field, and per- haps angiography would be the next steps in evaluating unexplained vi- sual loss. A mild optic neuropathy or prior vascular event could be missed in the pre-operative evaluation of a patient with a dense cataract. On the other hand, the patient's topog- raphy raises some concern. The topographic indices such as the shape factor indicate an essentially normal surface, but the map does not look completely normal. There are areas that could not be digitized by the topographer's software, and these areas are not lo- calized only to the superior portion, which may be covered by a slightly ptotic lid or lashes. I wonder whether the patient has some mild surface condition such as anterior basement membrane dystrophy. If all of your testing fails to disclose the cause of his visual complaint, go back and re-examine the patient!" Keith Baratz, M.D. In this case, re-examining the patient was a very good idea. On closer inspection of the cornea, it could be seen that the patient had a subtle intraepithelial abnormality. Specular reflection of the corneal surface revealed an "orange peel" quality to the epithelium, and look- ing at the epithelium closer under high magnification revealed multi- ple, miniscule, waxy or oily-looking intraepithelial inclusions or cysts that looked similar to cornea guttata on retroillumination (however, these were within the epithelium). This patient had Meesmann's corneal dystrophy. This is a rela- tively rare corneal dystrophy that presents with multiple intraepithe- lial cysts that may be rather subtle. In some cases these cysts can cause recurrent erosions (not the case here), but generally the effect on vi- sion is minimal if the ocular surface is not affected. Generally patients are asymptomatic unless the cysts are superficial and recurrent erosion develops; however, in this case the ocular surface was smooth as the cysts were relatively deep. SD-OCT of this patient's cornea revealed the cysts to be seen rather deep within the corneal epithelium. This patient had Meesmann's corneal dystrophy. This is a rela- tively rare corneal dystrophy that presents with multiple intraepithe- lial cysts that may be rather subtle. In some cases these cysts can cause recurrent erosions (not the case here), but generally the effect on vi- sion is minimal if the ocular surface is not affected. Generally patients are asymptomatic unless the cysts are superficial and recurrent erosion develops; however, in this case the ocular surface was smooth as the cysts were relatively deep. SD-OCT of this patient's cornea revealed the cysts to be seen rather deep within the corneal epithelium. Suggestions for treatment Now I had a better understanding of why this patient was unhappy with the multifocal lens in his left eye. The light scattering caused by the epithelial abnormality was being amplified by the diffractive optics of the multifocal implant, causing the patient to be dissatisfied with the quality of vision. Some of my colleagues re- sponded to this finding: "AH HA! Well now we have a reason for decreased contrast sensi- tivity that is synergistic with the de- creased contrast from the light splitting of a multifocal lens. This patient won't see his best with the multifocal, and I doubt any lamellar surgery or laser will leave the cornea sufficiently pristine to be best suited to multifocality. Exchange the lens for a monofocal (or a bit risky, a Crystalens)." Lisa Arbisser, M.D. "There seem to be two options in this case. 1. We could PTK/PRK the cornea to help the Meesman's symptoms and reduce the hyperopia and astig- matism and see what the patient thinks of the vision. 2. We could swap the IOL for the correct power monofocal (toric?) and see how the patient reacts to the vision. Later he could have PTK for the Meesman's, prn. Being the conservative wimp that I am, I would probably opt for September 2011 A multifocal mystery Figure 3 Source: Steven G. Safran, M.D. Figure 4 Source: Steven G. Safran, M.D. The other eye Source: Steven G. Safran, M.D. continued on page 28 Figure 5 Source: Steven G. Safran, M.D.

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