October 2011

 

NEWS & OPINION

 

Anterior segment grand rounds

A multifocal mystery


by Steven G. Safran, M.D.

 
 

Steven G. Safran, M.D.

Steven G. Safran, M.D.

This month, EyeWorld introduces a new column devoted to case-based learning, which we are calling "Anterior segment grand rounds." Steve Safran is a cornea fellowship-trained anterior segment surgeon practicing in Lawrenceville, N.J. Steve has a busy surgical referral practice, and I have always been impressed with his surgical insights and thoughtful analytical approach. For this reason, I have asked him to lead our grand rounds sessions in which he will ask other clinicians how they would handle a difficult case from his own practice. We invite EyeWorld readers to submit an interesting or perplexing case of their own to Steve, much as they might present that case to colleagues at their local grand rounds. Discussing interesting cases is a great way to share ideas and experiences, and we hope you'll enjoy learning from these practical case-based discussions.

David F. Chang, M.D., chief medical editor

If you have a case that you would like to send to Dr. Safran for consideration as a "case of the month" for the ASGR column please contact him at safran12@

comcast.net

 
Corneal topography

Eye topography

Figure 1 Source: Steven G. Safran, M.D.

Specular microscopy

Figure 2 Source: Steven G. Safran, M.D.

ocular surface Figure 3 Source: Steven G. Safran, M.D.

Figure 4 Source: Steven G. Safran, M.D.

eye The other eye Source: Steven G. Safran, M.D.

Figure 5 Source: Steven G. Safran, M.D.

Case presentation

A 51-year-old patient was referred in because he'd had cataract surgery 1 year earlier with a ReSTOR multifocal implant (D1 model, Alcon, Fort Worth, Texas) placed in his dominant left eye and he wasn't happy with it. He felt his vision was worse than in the other eye, which had a moderate nuclear sclerosis/cortical cataract, and that he had less than acceptable vision for both distance and near as well as glare at night. His surgeon had waited 1 year for "cortical adaptation," and after the patient noticed no real improvement, he was referred to me for evaluation and treatment. The referring surgeon was perplexed as to the patient's dissatisfaction with the vision in this eye even with his manifest refraction in place because all the tests done at his office were normal and the implant was perfectly centered.

When I examined the patient his vision was 20/30+1 in the phakic OD eye with a correction of 0.75-0.5X65. His pseudophakic OS (the eye with the multifocal implant) was 20/25-1 with a correction of +0.25-1.25X112. Subjectively, however, he felt the vision was not as good in the left eye (the multifocal psuedophakic eye) as the other eye with the moderate cataract. I refracted both eyes and put this refraction in the phoropter in front of him. I then placed 3 diopters base up in front of his right eye and 3 diopters base down in front of the left to create diplopia. The patient was unaware of which image, the upper one or the lower one, was from which eye; however, he consistently picked the image from the phakic right eye as the sharper and clearer one even though he could read a bit further down the chart with the left eye. I see many patients on referral for unhappy outcomes from cataract surgery, and often patients will say that they saw worse in the operated eye, perhaps because they are disappointed or even angry about their surgery. Using this prism-induced diplopia test I can mask patients so they don't know which image is from which eye and determine how the images from the two eyes compare. Often patients prefer the operated eye under these conditions, but in this case the patient's responses were consistent with his complaint. This patient was clearly having a problem with image clarity from his left eye relative to the right.

The patient's testing did not readily reveal the source of his problems. He had no RAPD, and VF testing was normal. OCT of the optic nerve and macula were unremarkable. Corneal topography, while not perfect, was not consistent with his complaints (Figure 1). Specular microscopy did not reveal the source of his problems (Figure 2). He had no ocular surface staining with lissamine green or fluorescein. His implant was well centered with a 360-degree rhexis overlap of the optic, no evidence of tilt, and although there were some very slight posterior capsule changes, I did not feel these were the source of his problems (Figure 3).

Roundtable discussion

I presented the information gathered to my panel of experts: Jeff Whitman, M.D., Dallas, Texas, Lisa Arbisser, M.D., Iowa and Illinois Quad Cities, Joe Sokol, M.D., Shelton, Conn., Brad Oren, M.D., Palm Beach, Fla., Brian Kim, M.D., Dalton, Ga., Keith Baratz, M.D., Rochester, Minn., Jim Lewis, M.D., Philadelphia, Penn., Jeff Horn, M.D., Nashville, Tenn., and Ed Hedaya, M.D., Lakewood, N.J., to get some thoughts on where to go from here. We had a "grand rounds" type of discussion via the internet, and some felt that 1 year was a long enough trial of this patient's neuroadaptation to consider this a "multifocal failure" and to justify consideration of an IOL exchange.

Here are my colleagues' responses:

"In summary, this patient had 'perfect' surgery with a well-centered IOL, no macular disease, no ocular surface disease, no endothelial dysfunction, no HVF defects, no color defects, no RAPD, minimal PC changes, and was never happy with the VA. It seems this patient is one of those ReSTOR patients who could never and will never tolerate the multifocality. I would not YAG the PC since the patient's sxs occurred immediately after surgery and thus the PCO is unlikely the cause for the unhappy VA. I think the patient needs an IOL exchange, and I would choose a Crystalens (Bausch & Lomb, Rochester, N.Y.) if he wants some presby-correction.If he doesn't want presby-correction, I would choose a monofocal aspheric IOL due to the persistent glare and night time sxs."

Brian Kim, M.D.

"I would like to see more cells on the specular microscopy exam. I would remove and replace with either a traditional aspheric lens or if the bag looked really good and the patient desired a better range of vision, 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 topography."

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 following reasons. He is phakic in one eye with a mild cataractalways dangerous as one's natural lens is a tough comparison to a multifocal unless the cataract is relatively dense.

He has too much residual refractive error in the left eye in my opinion 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 topography 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 concerned about some tilt in the IOL even if it grossly appears to be centered in the rhexis. Do we know if there are any problems with the stability 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 multifocal 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 majority of the common causes of poor vision after cataract surgery. Color vision testing, a visual field, and perhaps angiography would be the next steps in evaluating unexplained visual 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 topography 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 localized 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 looking at the epithelium closer under high magnification revealed multiple, 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 relatively rare corneal dystrophy that presents with multiple intraepithelial cysts that may be rather subtle. In some cases these cysts can cause recurrent erosions (not the case here), but generally the effect on vision 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 responded to this finding:

"AH HA!Well now we have a reason for decreased contrast sensitivity that is synergistic with the decreased 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 astigmatism 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 the latter, as I don't think he will ever be happy with a MF considering the natural tendency of the Meesman's to recur."

Brad Oren, M.D.

Treatment

Given the finding of Meesmann's, I discussed the options with the patient. Although superficial keratectomy could eradicate the cysts temporarily, they do recur, and this is really a treatment more effective for the recurrent erosion symptoms associated with Meesmann's than to deal with any visual problems, which will most definitely recur over time. Given that this patient was from a 4-hour drive away, I did not feel it would be a productive experiment to try this. It has been reported that soft contact lens wear will reduce the number of cysts in Meesmann's (www.ncbi.nlm.nih.gov/pmc/articles/PMC1298733/pdf/taos00015-0195.pdf), and I offered this option to the patient, but he did not wish to try it. After discussing the various options the patient decided that he wished to move forward with an intraocular lens exchange with a standard monofocal aspheric implant. The option of the Crystalens was discussed but given that the previous surgery was done 1 year before, I did not feel I could guarantee a good accommodative outcome and we thus decided against it. Here is a link to the video of the surgery: www.youtube.com/watch?v=wujJw_YPfHE.

The patient experienced immediate resolution of his visual complaints after the surgery and is now happy with the quality of his vision. No treatment of the cornea was required.

"Any corneal findings that affect the path of light, such as Fuchs,' EBMD, hereditary disorders, DES, irregular astigmatism, large vitreous floaters, and so forth are a contraindication to multifocal IOLs due to their adverse effect on MTF (modulation transfer function). One has to wonder how the vacuoles formation in AcrySof [Alcon] material affects the MTF also. Despite what is espoused, it is very difficult to accept that this has no affect on MTF."

Ed Hedaya, M.D.

Take-home points

I feel this case illuminates several important points. The first is that although we've all become more aware of the importance of testing such as topography and OCT to help us better understand our premium IOL patient outcomes, we can't overlook the importance of a careful clinical examination to pick up the things that testing simply can't. In this case a careful slit lamp exam picked up the pathology that was missed on testing.

The second point is that the visual function of patients with diffractive multifocal implants is more "labile" or easily and significantly degraded by processes that would be relatively insignificant otherwise. These may include relatively mild astigmatism, posterior capsule haze, dry eye, and epithelial abnormalities that might be asymptomatic in a phakic patient or a patient with a monofocal implant. When we evaluate patients for a multifocal implant, it is wise to carefully evaluate them not just for existing pathology but also to consider what pathology they may face down the road as they get older in an actuarial analysis of risk benefit ratio of the lens for patients as they age.

Editors' note: Drs. Baratz and Kim have no financial interests related to this case. Dr. Whitman has financial interests with Alcon and Bausch & Lomb and does research for ReVision Optics (Lake Forest, Calif.).

Contact information

Safran: safran12@comcast.net

Related articles:

Multifocal, multifocal toric, and other lenses

Multifocal lenses for the pediatric set? by Michelle Dalton EyeWorld Contributing Editor

Clear lens extraction with multifocal IOL implantation

Multifocal or monofocal? by J.E. “Jay” McDonald II, M.D.

A multifocal mystery A multifocal mystery
Ophthalmology News - EyeWorld Magazine
283 110
216 162
,
2017-03-15T03:48:45Z
True, 10