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Optimizing outcomes with laser vision correction to enhance presbyopic IOL results

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The growth of presbyopic IOLs has led to a solid contingent of happy patients. However, with the increased number of presbyopic IOL procedures, the number of patients who require either LASIK or surface ablation enhancements to optimize their visual results has also increased. To best meet patient expectations, ophthalmologists need to determine whether presbyopic IOL patients who are not satisfied with their vision are eligible for laser vision correction to address their visual complaints. If refractive surgery is planned, surgeons can optimize their results with pharmacologic control of pain and inflammation following refractive surgery.

Ophthalmologists performing laser vision correction on patients who have had previous presbyopic IOLs must think as refractive surgeons. —William B. Trattler, MD

Ophthalmologists performing laser vision correction on patients who have had previous presbyopic IOLs must think as refractive surgeons. Preoperative topography is one of the key eligibility tests, as it can help identify patients with conditions such as forme fruste keratoconus, frank keratoconus and pellucid marginal degeneration. It is important to look for even subtle cases of these diseases preoperatively. Patients who are identified with these conditions prior to presbyopic IOL implantation should be informed that they are not eligible for LASIK or incisional refractive surgery. However, in certain instances, patients with small degrees of forme fruste keratoconus can consider surface ablation, although patients must be informed that their visual results may not be as good as the results for patients without forme fruste keratoconus.¹ As well, a risk of progression of forme fruste keratoconus to keratoconus always exists.

Surface ablation

By using surface ablation, ophthalmologists can improve visual outcomes in presbyopic IOL patients with residual refractive errors. Our improved understanding of surface ablation has allowed us to minimize the risk of haze and patient discomfort, as well as provide for faster visual recovery. Multiple surface ablation techniques are available. With photorefractive keratectomy (PRK), ophthalmologists remove the epithelium with a brush, laser or diluted alcohol, or manually with a spatula or blade. Laser-assisted subepithelial keratomileusis is a technique in which diluted alcohol is applied to the surface of the cornea for 20 to 30 seconds, loosening the epithelium. After the epithelium is moved to the side, the excimer laser reshapes the cornea, and then the epithelium is replaced. Finally, an epikeratome, favored by some surgeons, is an automated device that removes the epithelium (Table). However, these devices bring some additional risk to surface ablation, as they can create stromal incursions that can negatively affect visual results.²

Source: Trattler WB

Many steps should be taken to ensure positive outcomes from surface ablation. Haze prevention is the first issue that must be addressed. Avoiding early

onset haze, which occurs if there are delays in epithelial healing, is important, and is related to maximizing the recovery of the epithelium. If the epithelium has delayed healing, then interventions are required to speed healing. Steps that can be used include stopping non-essential drops that contain preservatives, placement of punctal plugs and/or switching contact lenses. Patients should be instructed to stop the use of topical anesthetic drops.

When a patient with a clear cornea after surface ablation develops haze 3 to 12 months postoperatively, it is termed late-onset haze, which differs from early onset haze. Late-onset haze appears to be related to UV exposure and deeper, less smooth ablations. Late-onset haze can effectively be prevented in most cases by the use of intraoperative mitomycin C.

Pain control

Providing a smooth, comfortable postoperative course is critical following surface ablation, as presbyopic IOL patients may be surprised if they experience dramatically more pain than with their original cataract surgery. To help ensure a comfortable experience, many ophthalmologists performing surface ablation provide diluted or regular anesthetics for their patients. It is recommended that diluted anesthetics be mixed by a compounding pharmacy, because in many states, mixing of medications can only be legally performed by pharmacists. Anesthetics can be safe and help control pain if used properly. However, in cases where there are delays in epithelium healing, it is critical that the surgeon or the surgeon’s staff retrieve the anesthetics to avoid overuse or abuse.

Another important item for pain control is the use of a bandage contact lens. Bandage contact lenses provide comfort for patients who have undergone laser vision correction. The Acuvue Oasys (Vistakon, Jacksonville, Fla.) was recently approved by the U.S. Food and Drug Administration for use as a bandage contact lens.

Chilling the cornea is an additional technique that has proven helpful in the reduction of pain in patients undergoing surface ablation. Daniel S. Durrie, MD, described his method of using a frozen sponge soaked in balanced salt solution (BSS, Alcon Laboratories, Inc.) to cool the cornea before and after laser ablation. ³ Another method is to place a bottle of BSS in a freezer and place the semi-frozen solution on the cornea for 30 seconds immediately after ablation. Bruce Larson, MD, showed that this method reduced pain scores compared to no chilling of the cornea.⁴

Patients who have preoperative dry eye will take longer to heal and will experience more pain in the early postoperative period following surface ablation. —William B. Trattler, MD

Another cause of early postoperative pain is dry eye. Ophthalmologists must perform careful preoperative dry eye testing. Patients who have preoperative dry eye will take longer to heal and will experience more pain in the early postoperative period following surface ablation. Punctal plugs and cyclosporine are two options for use by surgeons to help maximize the health of the ocular surface in dry eye patients.

A final option for pain control is the use of topical nonsteroidal anti-inflammatory drugs, which have been shown in FDA studies to reduce pain postoperatively.⁵ However, it is important to know how to use the available drop formulations. Some NSAIDs can be placed directly on the cornea for 4 to 5 days, while others, such as nepafenac, may delay epithelial healing if they are placed directly on the cornea.⁶ Ophthalmologists who use nepafenac after surface ablation should administer the drops after the bandage contact lens is inserted and limit the dosage to two to three times per day for 2 to 3 days. The use of nepafenac for longer than 3 days has been shown to delay in epithelial healing and early corneal haze.⁷

Dry eye

Patients who undergo presbyopic IOL procedures are often older, with most patients in my practice ranging in the 50s to 80s. Compared to younger patients, these patients are at a higher risk of having pre-existing dry eye. It is important for ophthalmologists to identify dry eye syndrome preoperatively. A number of studies have shown that topical cyclosporine can help improve the results of LASIK.⁸ Studies also show that cyclosporine provided better visual results and better quality of vision for patients implanted with presbyopic IOLs.⁹

Conclusion

Surgeons who think like refractive surgeons can identify the key issues that are leading to the patient’s visual complaints. —William B. Trattler, MD

Presbyopic IOLs have had a considerable impact on ophthalmology practices. However, 5% to 20% of patients can be less than satisfied with their initial visual results. Surgeons who think like refractive surgeons can identify the key issues that are leading to the patient’s visual complaints. Also, they can help develop a treatment plan, which may include surface ablation or LASIK enhancements.

When considering laser vision corrections to improve the visual results of presbyopic IOLs, it is important that surgeons carefully evaluate topographies preoperatively and identify abnormal shapes. Surgeons who will be providing surface ablation must optimize the results, which includes using techniques for haze and pain control as well as identifying dry eye preoperatively. With the continued increase in presbyopic IOL usage, success in identifying and treating underwhelmed patients will lead to an improved pool of satisfied patients.

References

1. Hardten DR, Davis EA, Lindstrom RL. Using laser vision correction to retreat eyes after multifocal IOL implantation. Presented at: Annual Meeting of the American Society of Cataract and Refractive Surgery. April 7, 2008; Chicago, Ill.
2. Trattler WB. PRK vs. LASEK vs. Epi-LASIK: Is there a difference? Presented at: Hawaiian Eye; January 25, 2008; Waikoloa, Hawaii.
3. Lipner M. Smooth moves for surface ablation. EyeWorld. 2006;11:39.
4. Gutman C. Use of preoperative semi-frozen BSS drops helps reduce pain after epi-LASIK. Ophthalmology Times. 2006;31;22:58.
5. Solomon KD, Donnenfeld ED, Raizman M, et al; Ketorolac Reformulation Study Groups 1 and 2. Safety and efficacy of ketorolac tromethamine 0.4% ophthalmic solution in post-photorefractive keratectomy patients. J Cataract Refract Surg. 2004;30:1653-1660.
6. Trattler W, McDonald M. Double-masked comparison of ketorolac tromethamine 0.4% versus nepafenac sodium 0.1% for postoperative healing rates and pain control in eyes undergoing surface ablation. Cornea. 2007;26:665-669.
7. Trattler W, Stulting D, Abad J, et al. Delayed epithelial healing with nepafenac 0.1% ophthalmic suspension. Presented at: Joint Meeting of the American Academy of Ophthalmology and the Asia Pacific Academy of Ophthalmology; November 11-14, 2006; Las Vegas, Nev.
8. Ursea R, Lovaton M, Ehrenhaus M, et al. The role of Restasis in faster visual acuity recovery after refractive surgery. Paper presented at: Annual Meeting of the Association for Research in Vision and Ophthalmology; May 4, 2005; Fort Lauderdale, Fla. J Refract Surg. In press.
9. Salib GM, McDonald MB, Smolek M. Safety and efficacy of cyclosporine 0.05% drops versus unpreserved artificial tears in dry-eye patients having laser in situ keratomileusis. J Cataract Refract Surg. 2006;32:772-778.