A case of SEALs

Judy Kwan, Clinical Optometrist, BOptom (Hons), International Clinical Trials Centre - Institute for Eye Research Limited

Judy Kwan is a Clinical Optometrist at the International Clinical Trials Centre - Institute for Eye Research, based in Sydney, Australia. She is responsible for conducting clinical research trials in the area of contact lenses. She graduated with honors in Optometry at the University of New South Wales and is currently working towards a MOptom degree on a part-time basis.

A 32-year-old female Caucasian experienced contact lens wearer presented for a routine 6-month contact lens aftercare visit. She had been attending our clinic for the past 5 years on a regular follow up basis and had not experienced any adverse events or reported symptomatic problems. She had been wearing 8.6/14.0 Balafilcon A (Bausch & Lomb, Rochester, NY) lenses successfully for the past 4 years on a daily wear (DW) monthly replacement schedule for 12 hours a day with the use of OptiFree Replenish (Alcon, Fort Worth, Texas) disinfecting solution.

During this visit, she expressed interest in modifying her wearing modality to include some extended wear (EW). She was advised to continue wearing her Balafilcon A lenses on a monthly replacement schedule and change her modality to EW including fortnightly disinfection of lenses with the use of Optifree Replenish. She was requested to return for an aftercare visit towards the end of the first month of EW.

Figure 1. Superior temporal SEAL and associated limbal redness in the right eye under white light viewing conditions

At the 2-Week follow-up visit with no lens wear:
Bilateral SEALs had resolved. She was advised to return to DW of Balafilcon A lenses.

One month after resuming DW:
No further reoccurrence of SEALs. Future follow-up visits were recommended for every 6 months unless symptoms or problems occurred.

After 6 months of contact lens wear there were no reported symptoms or problems. The corneas exhibited mild dehydration staining in the superior and inferior quadrants with the absence of further complications or presentation of SEALs. This corneal staining, however, was of no clinical significance.

Alternative Treatment Plan:
SEALs are usually asymptomatic so regular follow up visits after resuming lens wear are required to look for possible future reoccurrence, for which there is a possible 8-33% chance [1, 2]. In most situations, patients may be refitted [3] with the same lens design and parameters, however, if SEALs were to re-develop a different lens material and design should be considered.

In this case study, the wearing modality was changed as SEALs had occurred during EW and the patient had successfully worn the same lens type on a DW basis for the previous 4 years. If SEALs reoccurred, a new lens type with a slightly lower modulus and/or better surface wettability would have been selected.  Should the fit not have been ideal, changing the lens design such as the base curve or lens type may have also been an option. Recent material modulus and design modifications and expansion of the base curve of Balafilcon A lenses have allowed a wider selection of lenses which give practitioners more options to manage this complication.

Discussion and Conclusion:
Since the introduction of first generation silicone hydrogels in 1999 [4], SEALs have reemerged as a typical  contact lens related adverse event.

Risk factors which pre-disposed this patient to develop SEALs may have been her relatively steep corneal curvatures [1], thicker contact lens periphery [5] from the higher prescription and her wear of a higher modulus [1] contact lens. Despite this she had minimal deposition [6] on her contact lenses, good wettability and optimal tightness [7] of the contact lenses upon fitting and during follow-up visits.

One  hypothesis that has been proposed [8] to explain the occurrence of SEALs is that inadequate lens flexure in the superior corneal region, when combined with eyelid forces, squeezes out the post-lens tear film. This increases the frictional interaction between  the  cornea and lens surface,  causing a lifting of epithelial cells that gives  the classic appearance of SEALs [8].

In the present case, overnight wear may be the reason for the reduction in the thickness of the post-lens tear film. Thus, reverting to the original lens wearing modality effectively eliminated this complication. If a change in wearing schedule had not been effective, the expanded silicone hydrogel range that has become available over the past decade would have made it possible to select another material as an alternative means of preventing the reoccurrence of SEALs.

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