Exploring Different Approaches in a Complex Case

History

This patient is a 48-year-old female teacher who has bilateral keratoconus. She visited our clinic for the first time in January 2021. She reported that she first wore soft toric lenses and then had worn piggyback lenses for some time in the past, but she developed lens intolerance. The patient reported trying different frequent replacement soft lenses with no success. She also reported that she had previously developed a corneal ulcer and then gave up on contact lenses. She was wearing high-minus-power eyeglasses that provided reasonable visual acuity limited to central vision. She complained of poor vision. Her spectacle Rx was:

OD –5.00 –2.50 x 90 VA 20/25

OS –7.50 –3.75 x 80 VA 20/60

Corneal Biomicroscopy

The eye exam revealed healthy corneas with no scars and reasonable corneal thickness despite the high minus power; the thickness of the right eye was approximately 90% and of the left eye was 75% compared to a normal cornea. We also observed a tendency for mydriasis in dim light. The meibomian glands had slightly migrated to the tarsal conjunctiva. The patient was prescribed omega-3 supplements and was instructed to use a phenylephrine hydrochloride/polyvinyl alcohol drop and also to gently massage the meibomian glands.

We first updated her prescription to obtain the best possible visual acuity (VA) with eyeglasses:

OD –5.00 –3.50 x 125 VA 20/20^-3

OS –8.00 –4.50 x 65 VA 20/50

Although VA improved from the previous prescription, the visual field with this prescription was reduced, and the patient did not have adequate lateral vision. We decided to conduct a scleral (Figure 1 top, OD) and a specialty GP (Figure 1 bottom, OD) lens evaluation.

Contact Lens Evaluation

We conducted specialty corneal GP and scleral lens diagnostic fittings in January 2021, but the patient did not return to proceed with the fitting until July. The first evaluations from January showed a better visual outcome with the corneal GPs, but she preferred the initial comfort of the sclerals.

We proceeded with the scleral lens fitting, as she preferred. The initial evaluation revealed minor scleral toricity, with an elevated edge in some areas. With quadrant-guided modifications to the haptic landing zone, the resulting scleral lenses fit well (Figure 2).

The patient likes to go out on the weekends to have dinner or just chat. She was previously informed that reading glasses were necessary because of her age, but she asked whether another option was available. We determined that her right eye was the dominant eye, and we prescribed her left eye with a +1.50D under-correction to help improve near vision.

The resulting fit had good corneal and limbal alignment, with a gentle landing and an optimal sagittal height (sag). The scleral lens parameters were:

OD 42.00D (8.03mm) base curve (BC), –2.75D power, 17.5mm overall diameter (OAD), 13.6mm optic zone diameter (OZD), 5.224 sag, Dk 200

OS 42.75D (7.89mm) BC, –4.50D, OAD 17.5mm, OZD 13.6mm, 5.393 sag, Dk 200

The resulting visual acuity was:

OD AV 20/25 J3

OS AV 20/50^-2 J1

During the first follow-up visit, the patient complained that her distance vision was not good; she did not achieve a balanced neurosensory adaptation. We added the minus power needed to improve distance vision, which improved the visual acuity OS to 20/30^-1. However, it was not enough to satisfy the patient; although distance vision was acceptable, she could not read her smartphone. Now the journey began.

In an attempt to improve her distance vision, we changed her scleral lens OS to eliminate the attempted monovision. The resulting parameters were:

OD 42.00D (8.03mm), –2.75D, OAD 17.5mm, OZD 13.6mm, sag 5.224, Dk 200

OS 42.75D (7.89mm), –6.00D, OAD 17.5mm, OZD 13.6mm, sag 5.393, Dk 200

The resulting visual acuity was:

OD AV 20/25 J3

OS AV 20/40⁺² J4

None of these attempts satisfied the patient, so we decided to start over and review our options.

Considering Additional Options

We discussed this case with our medical staff. After many considerations about the scleral lens fitting, we concluded that the tendency to mydriasis was responsible for a higher-order aberration (HOA) (coma). During our discussion, I suggested the following strategy, just as an experiment.

Scleral Lenses and Off-Label Use of Brimonidine Tartrate 0.1% Brimonidine tartrate ophthalmic solution 0.1% is a relatively selective alpha-2 adrenergic receptor agonist (topical intraocular pressure-lowering agent).¹ One known side effect of this drug is that induces temporary miosis.²

I’ve heard that many corneal surgeons neutralize or minimize HOAs in post-laser refractive surgery by using brimonidine tartrate 0.1% off label to induce miosis. I researched the use of this drug and also talked with some ophthalmologists who perform laser surgery; prominent surgeons with whom I spoke indicated that there were no contraindications for long-term use and that it was safe. During my online search, I noticed that my idea was not original. There are two publications from 2013 and 2016 on the use of this drug with GP lens wear.^3,4 The difference was that we were testing it with scleral lens wear.

We discussed whether the drop could be instilled while the scleral lens was on the eye or whether it should be instilled before lens application. We decided to try it with the lens on eye, as this would be the natural situation if the patient would be using the drug only in the evening or in low-light conditions.

The idea was to determine whether off-label use of this medication to induce miosis would improve her visual acuity and quality. We measured the pupils of both eyes using a pupil ruler, both with the lights on and in dim illumination. The pupil sizes, with lights on, before the experiment were:

OD 6.5mm OS 5.5mm

We performed a controlled, in-office experiment with one drop of brimonidine tartrate 0.1% OD and OS, instilled while the scleral lens was on her eye (Figure 3), and sent the patient to the waiting room for 20 minutes. When we saw her again, she reported that she already noticed an improvement in her distance and near vision; this was a surprise, as we imagined that the effect would take a longer time. We measured the pupil size again; OD was 4.5mm, OS was 4.0mm or less (20 minutes after the drops).

We compared pupil size in both eyes with the light on again, as the drug was instilled in both eyes, and the findings were:

OD 4.5mm OS 4.0mm

We also reviewed her visual acuity. She had improved one line, reaching the following VA:

OD AV 20/20^-2 J1

OS AV 20/25^-3 J1

The patient was happy and motivated with the result, but we explained that it was only an experiment and required further investigation. This is an ongoing study that we are currently conducting. After one hour, her pupil sizes were:

OD 4.0mm OS 3.5mm

Some concerns that we had were whether we should prescribe the drug for only her worse eye or for both, whether it would compromise lateral vision, and also how long the effect would last.

GP Lenses A few weeks later, the patient returned for a specialty corneal GP lens fit. We diagnostically fit an aspheric double-base-curve GP in the following parameters:

OD BC 52D x 45D (6.49mm x 7.50mm), –10.50D, OAD 9.8mm, OZD 6.0mm, Dk 75, VA 20/20^-3 J2

OS BC 54D x 46D (6.25mm x 7.34mm), –18.25D, OAD 9.8mm, OZD 6.5mm, Dk 75, VA 20/30^-1 J2

Fitting keratoconus is always challenging, and sometimes it is necessary to customize the posterior lens profile to achieve the best possible result. Generally, we have not seen significant differences in visual acuity with scleral and GP fittings; in this case, it was clear that the visual acuity improved with both types of lenses.

The corneal GP lens fit well, but the patient reported contact lens awareness; this is natural because GPs require a period of corneal adaptation. The fact that she was already wearing scleral lenses had a negative impact in terms of initial comfort. Although we explained the adaptation schedule to her and she tried to comply, she occasionally wore her scleral lenses. This compromised the adaptation.

We were concerned that the patient might lose confidence with contact lens wear after these attempts, but we decided to explore more options. It was clear that scleral lenses would not improve her vision unless we prescribed the brimonidine tartrate 0.1%. We also noticed that GPs were able to offer her much better VA, most likely because they are closer to the eye and have a smaller optical zone, so they result in fewer HOAs.

I suggested diagnostically fitting an intralimbal GP lens with a design similar to the corneal GP. Following the diagnostic fitting, the final parameters were:

OD BC 50D x 45D (6.75mm x 7.50mm), –8.50D, OAD 12.3mm, OZD 7.5mm, Dk 100, VA 20/20^-3 J2

OD BC 52.50D x 45D (6.43mm x 7.50mm), –15.25D, OAD 12.3mm, OZD 8.0mm, Dk 100, VA 20/30^-1 J2

Note that in changing from a corneal 9.6mm GP to an intralimbal GP design, we needed to flatten the base curve, because the larger overall and optical zone diameters increased the sag value of the intralimbal GP.

Figure 5 shows these lenses on eye. Note that the lens covers the entire cornea from limbus to limbus, which can make it difficult to perceive. The patient reported good initial comfort with the new lenses, and her visual acuity was similar to that with the previous corneal GPs. For intralimbal designs, it is OK for the lens to exhibit minimum or no movement if there is lacrimal exchange. We instilled fluorescein on the superior conjunctiva and waited several minutes before evaluating.

After a few minutes, the fluorescein made its way under the lenses. We instructed the patient to blink and to move her eyes naturally, as she felt comfortable wearing the lenses. We examined her corneas after 15 minutes. Figure 6 shows the fluorescein pattern using a cobalt blue light and yellow filter.

The peripheral cornea is much flatter compared to any other zone, so we designed a larger aspherical periphery to protect the limbus and to allow some tear exchange. The lenses exhibit minimum or no movement, but the fact that the fluorescein entered behind the lenses demonstrates that tear exchange is occurring, and the use of a higher-Dk material will also help to maintain corneal physiological health.

A few days after the patient started wearing the intralimbal GPs, she reported that she was satisfied with the result. At the time of this writing, she was scheduled for a follow-up visit in two weeks.

Conclusion

Any contact lens specialist should have resources to explore different options when the first choice does not meet a patient’s needs. These include an understanding of corneal and scleral GP designs and fitting characteristics as well as lab consultants to provide advice and assistance. Listening to and observing patients as well as paying attention to their daily activities and to what their visual needs and expectations are also helps with understanding which type of lens is the best choice.

If we rely on only certain type of lenses, our options will be limited, and it is possible that patients will give up the fitting. Conversely, when we explore different options after initial attempts fail, there is a greater chance of finding the best possible fit that resolves the case. When that is achieved, those patients tend to become patients for life.

References

1. WebMD. Brimonidine Drops - Uses, Side Effects, and More. Available at https://www.webmd.com/drugs/2/drug-13977-1958/brimonidine-ophthalmic-eye/brimonidine-0-025-solution-ophthalmic/details . Accessed Nov. 24, 2021.
2. Shemesh G, Moisseiev E, Lazar M, Kesler A. Effect of brimonidine tartrate 0.10% ophthalmic solution on pupil diameter. J Cataract Refract Surg. 2011 Mar;37:486-489.
3. Brujic M, Miller J. Shedding Light on Pupil Size Dynamics. Rev Cornea Contact Lens. 2013 Oct 15. Available at https://www.reviewofcontactlenses.com/article/shedding-light-on-pupil-size-dynamics-44390 . Accessed Nov. 24, 2021.
4. Brujic M, Miller J. Brimonidine Breakup. Rev Cornea Contact Lens. 2016 Jun 15. Available at https://www.reviewofcontactlenses.com/article/brimonidine-breakup . Accessed Nov. 24, 2021.

Mr. Bastos is the director and clinical instructor of specialty contact lenses at the Instituto de Olhos Dr. Saul Bastos (IOSB, and is the director and specialty lens consultant of Ultralentes, a small laboratory specializing in GP and scleral lens designs in Porto Alegre, RS, Brazil.