Complex Intraocular Lens Cases

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Complex Intraocular Lens Cases


Arun C. Gulani, MD, MS and Tracy Schroeder Swartz, OD, MS, FAAO, Dipl ABO


Unhappy premium intraocular lens (IOL) patients may result from problems with surgical candidacy and dissatisfaction with surgical outcome. Dissatisfaction may occur even when the surgery was performed perfectly. Often, the surgeon did not meet patient expectations, the visual quality is less than acceptable, or the surgeon failed to address the patient’s complaints.


Detailed preoperative evaluations are required to ensure there are no contraindications for presbyopia surgery. It is best to identify contraindications prior to surgery, and explain why the patient is not a candidate for the desired lens, rather than addressing a complaint after implantation. Patients with problematic expectations or previous refractive surgery are particularly difficult to satisfy. When evaluating a patient with surgical complications, it may be beneficial to consider a systematic approach, described in Table 12-1. Complications may be related to anatomy, lens-based problems, and patient symptoms and expectations.


ANATOMICAL COMPLICATIONS


Anatomical complications include structural changes to anatomy, such as corneal, iris, or vitreoretinal tissue problems. Ocular inflammation should be corrected prior to surgery, because any ocular surgery can increase both anterior and posterior segment inflammation. Meibomian gland dysfunction, blepharitis, conjunctival chalasis, allergic conjunctivitis, keratoconjunctivitis sicca, vernal conjunctivitis, demodex infection, lagophthalmus, trichiasis, and any other anterior segment abnormalities should be addressed with the patient prior to the procedure. Should these issues increase after surgery, the patient will typically feel the intraocular surgery caused the problem.


Case 1


A 57-year-old male presented following femtosecond laser–assisted cataract surgery with a TECNIS multifocal implant (Johnson & Johnson Vision). He reported his vision had been steadily decreasing in the weeks after surgery, with increasing ocular discomfort. He reported that by the end of the day, his vision left him unable to drive home from work comfortably. Unaided vision was 20/30 OS, and improved to 20/25 with -1.25 +1.50 x 160. The endpoint was soft and varied with blinking. He was unable to discern small changes in refraction. Slit lamp exam revealed significant neovascularization of the lid margins, frothing, and minimal expression (3/15 LL OU) of the meibomian glands. The tear film was thickened, and osmolarity was measured to be 350 mOsm/L. After using a lipid-containing tear 4 times a day and 50 mg doxycycline orally daily for 30 days, the central astigmatism improved. Best correction of 20/20 was achieved with -0.75 +0.75 x 155. He reported he was more comfortable driving at night and declined night vision driving glasses (Figure 12-1).




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Figure 12-1. Central astigmatism reducing the reading effect of a TECNIS implant and reducing best-corrected vision to 20/25. Treatment improved both unaided and best-corrected vision.




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Figure 12-2. Epithelial basement membrane dystrophy may complicate IOL calculations due to an irregular corneal surface.




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Figure 12-3. Salzmann’s degeneration may cause visual significant irregular astigmatism.


Corneal structural issues are best identified and treated prior to referral for phacoemulsification. Examples include epithelial basement membrane dystrophy (Figure 12-2), keratitis, Salzmann’s degeneration (Figure 12-3), Fuchs’ dystrophy, and keratoconus. Since the IOL power is calculated based upon the keratometry measurements, the corneal irregularity should be addressed prior to IOL calculation. Irregular astigmatism makes corneal power measurement inaccurate and results in residual refractive error. This is most commonly a problem in patients with a history of refractive surgery or keratoconus but is also a problem in patients with corneal degenerations or dystrophies. Corneal topography should be performed to assess the regularity of the corneal surface and need for a toric IOL. If the topographer can compare refractive keratometry readings with simulated keratometry readings, this task is easy. If there is a 1.0-diopter (D) difference in the refractive and simulated keratometry values, the risk of residual refractive errors increases (Figure 12-4).



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Figure 12-4. Irregular astigmatism manifests as a difference in refractive keratometry values compared to simulated keratometry values. This patient suffered from residual refraction due to irregular astigmatism complicating IOL calculation. Note the irregular corneal cylinder.


Pupil abnormalities, such as iris atrophy, large peripheral iridotomies, or Adie’s pupil, may cause problems with multifocal IOLs. Abnormalities in pupil shape after surgery may result in cases where miotic pupils were mechanically opened during phacoemulsification using iris hooks or a Malyugin ring (Microsurgical Technology). Increased pupil size may result in increased glare and halos.1


Case 2


A 58-year-old female presented for a second opinion. She had a history of radial keratotomy (RK) several years prior, followed by a TECNIS Symfony IOL (Johnson & Johnson Vision) implantation. She complained of poor vision, night glare, and halos. Unaided, she was 20/25 at distance and 20/60 at near. The pupil in the right eye was sluggish, distorted, and dilated. Both angle kappa and alpha were elevated (0.832 mm and 0.603 mm; Figure 12-5). Because the pupil was permanently dilated due to surgical trauma, topical miotics were attempted to determine if her symptoms would improve. Thankfully, she was pleased with the effect of 0.50% pilocarpine and was able to read 20/30 with pharmacological treatment.


Ocular alignment should be addressed preoperatively to ensure success using a premium lens. Clinical assessment of angle kappa and alpha should be performed prior to discussion of IOL options. Angle kappa is the difference between the visual axis and center of the pupil. This is particularly important in keratorefractive surgery for hyperopes or in presbyopic treatments (Figure 12-6).


Angle alpha is the angle between the visual axis and the center of the limbus. The center of the limbus is thought to represent the center of the lens capsule, and is used to predict where the IOL will be positioned after implantation. Current IOL technology employs haptics that center the IOL in the capsular bag. If the IOL within the bag is not aligned with the visual axis, the patient will not look through the center of the IOL. This will induce higher order aberrations and negatively affect visual function.2 Toric IOLs also require proper alignment but may be more forgiving then a multifocal IOL. Decentration of toric lenses may induce astigmatism or reduce the power of the cylinder resulting in residual refractive error.



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Figure 12-5. Pupil abnormalities, such as an irregular-shaped pupil following the use of iris hooks during cataract surgery can have deleterious effects on vision with a multifocal IOL.




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Figure 12-6. Angle kappa is the difference between the visual axis and center of the pupil. Angle alpha is the angle between the visual axis and the center of the limbus. The center of the limbus is thought to predict where the IOL will be positioned after implantation.


In addition to optical alignment, position of the IOL in the bag is related to the capsulorrhexis. A well-centered, properly sized capsulorrhexis is important for multifocal IOL function.3,4 Decentered capsulotomy may be problematic in multifocal IOL patients if the IOL fails to center in the bag.


Multifocal lenses have a lower threshold for YAG (yttrium-aluminum-garnet) capsulotomy, but must be handled with careful consideration since performing the YAG makes exchange extremely difficult. If the patient was initially happy, and then becomes unhappy with visual function due to posterior capsular haze, the YAG will most likely help. If the patient was never happy with the vision following implantation, YAG may be ill-advised. Capsular haze may alter the refractive error due to fibrosis or distort the vision (Figure 12-7). When performing a YAG, careful application to remove all strands beyond the optical zone and avoid hitting the IOL is recommended.


The posterior segment must also be evaluated in patients with visual complaints. Retinal abnormalities should be identified prior to multifocal implants since reduced macular function will impact the effectiveness of the IOL. Macular optical coherence tomography (OCT) scans are typically performed preoperatively for this reason (Figure 12-8). Three-dimensional, cube analysis is preferred to a macular scan using slices to ensure comprehensive evaluation. Early holes, asymmetric foveal depressions, epiretinal membranes, and slight retinal pigment epithelium disruptions or detachments may be an issue in a 20/20 eye with a multifocal lens.



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Figure 12-7. (A) A TECNIS Symfony lens 1 day status post-YAG procedure. The strands continue to reduce the vision subjectively. (B) Crystalens (Bausch + Lomb) with a poorly performed YAG. The procedure failed to improve the subjective vision. (C) Crystalens with an improperly performed YAG procedure. (D) Strands on a ReSTOR (Alcon Laboratories, Inc) IOL in a symptomatic patient.

Sep 1, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Complex Intraocular Lens Cases
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