BEYOND GPs AND SCLERALS: FITTING HYBRID LENSES

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A well-balanced approach to irregular corneas will enhance patient outcomes.

Hybrid lenses are now a mainstream option for patients with irregular corneas. In our practices, we provide a menu of options for these patients that assists in the decision-making process. The discussion goes something like this:

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SynergEyes’ UltraHealth hybrid
lens is a good solution for
numerous corneal irregularities.


Ms. Sanchez, now that we have established that you have keratoconus, we have some options for providing better vision. The standard of care for the last 40 years has been corneal gas permeable (GP) lenses. These lenses provide very good vision and are relatively inexpensive.

The newer options are hybrid and scleral lenses. Hybrid lenses have a GP center that is permanently bonded to a skirt of soft lens material. With hybrids, we get the same or better optical results as corneal GPs, because the lenses do not move from the top of the cornea to the bottom with every blink, and the skirt holds the optical portion of the lens centered on the eye. The skirt also prevents dust and debris from accumulating under the lens and causing the traditional immediate pain as with corneal GPs.

Scleral lenses are very large GP lenses that rest on the white part of the eye, the sclera. They are so large that they do not contact the cornea. Scleral lenses take the most number of visits to design properly and because of this, are the most expensive option.
Both hybrid lenses and scleral lenses are vaulting strategies, meaning the center of the lens does not hit the tip of the cone, and carry a lower risk for scarring on the tip of the cone.

We then make recommendations based on each specific case. In our practices, we tend to fit most mild-to-moderate keratoconus in hybrid lenses and reserve scleral lenses for severe to very severe cases. In a few patients with very low corneal hysteresis, a hybrid lens may fail due to the extraordinary amount of settling, and in those cases, we move them to sclerals. But, we will typically know this quickly, as we are dispensing lenses in much fewer visits than the typical scleral. We fit corneal GPs on patients who state that they cannot afford vaulting lenses or who prefer to stay in their current GP modality.

The following are two cases that we encountered and how we treated them with SynergEyes, Inc.’s UltraHealth’ hybrid lenses.

CORNEAL ECTASIA
A 25-year-old male was recently denied admittance into the military due to corneal ectasia found on his qualifying eye examination. He had worn soft contact lenses in the past but did not arrive wearing lenses. His chief complaints were blurry vision at distance specifically when driving and difficulty reading captions on the TV. Unaided visual acuities were 20/40- OU. Biomicroscopy, as well as the posterior segment, were within normal limits.

A mild case of keratoconus was confirmed with Placido-disk-based corneal topography and OCT pachymetry. We began diagnostic fitting with UltraHealth using sodium fluorescein (NaFl) and OCT, started with vaults of 250 and flat skirts OU. Actual vaults of each diagnostic lens were measured by OCT. Trial lens vaults were sequentially reduced until we achieved an OCT-measured vault of 101 OD and 106 OS. We observed no apical bearing, good centration, and movement on blink in both eyes after 20 minutes. After over-refraction was completed, final lenses were ordered as:

UH 100/-2.00/flat OD
UH 150/-5.00/flat OS

At the dispensing visit BCVA was 20/20 OU. The patient also reported excellent comfort and left with lenses.

ULTRAHEALTH LENSES
The UltraHealth hybrid lens is designed for numerous corneal irregularities, especially for keratoconus. The reverse geometry GP portion of the lens is designed to vault the apex of the cone or corneal irregularity. The silicone hydrogel skirt provides lens centration, stability, and comfort. The inner landing zone is the part of the gas permeable portion that helps to support the lens on the peripheral cornea. The soft cushion is the thickened part of the flexible silicone hydrogel skirt which facilitates the tear pump exchanging tears behind the lens during wear and bears the majority of the weight of the lens.

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The variable curve of SynergEyes’ UltraHealth FC lenses
is designed for oblate corneas.

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UltraHealth’s aspheric reverse geometry
vaults the apex of the cone or corneal irregularity.

BLURRED VISION
A 43-year-old female reported gradually progressive blurred vision at distance and trouble driving. She had a history of radial keratotomy. Her acuity with habitual soft toric contact lenses was 20/30-2 OD and 20/70 OS. Placido-disk-based corneal topography simulated k’s were 39.44/42.41 OD and 39.38/41.99 OS. Visual acuity with best spectacle correction of +0.50 -2.00 x 10 was 20/30 OD, and with +0.75 -2.75 x 30 was 20/25 OS. Slit lamp evaluation revealed corneal AK and RK incisions.

First diagnostic lens 205/-2.50/med yielded 20/30 OD, and 205/-2.50/flat yielded 20/25 OS OCT showed mild bearing OD and an acceptable fit OS. An increase in vault by 50 microns was indicated (255u) OD. The left lens was ordered as fit. Lenses ordered were:

UF 255/-3.50/med
UF 205/-2.50/flat

At the dispensing visit, sodium fluorescein (NaFl) evaluation and OCT showed good centration, no apical bearing and excellent movement on blink OU after 30 minutes. However, she complained of visual fluctuations and difficulty at near. Over-refraction showed +1.25DS OD and +1.00DS OS for 20/20 and comfortable vision OD, OS. The patient was taught insertion, removal, and care at this visit but current lenses were not dispensed. Final lenses ordered were UltraHealth Flat Curve (FC) 255/-2.25/med OD, and 205/-1.50/flat OS. She appeared satisfied with the results.

ULTRAHEALTH FC
While UltraHealth lenses can be used for vaulting any corneal ectasia, central corneal scars, and other irregularities, the UltraHealth FC Oblate Design was specifically designed for oblate corneas, including post-RK (radial keratotomy) and post-refractive surgery. UltraHealth FC utilizes the same design of the upper vaults of UltraHealth, but with a much flatter base curve. The initial 55 vault lens starts at 35.50 or 9.5mm. The variable lift curve of the GP rises to vault over the peripheral cornea, increasing sagittal depth, and then flattens out over the central portion of the cornea.

In our practices, UltraHealth FC has become the lens of choice for post-RK patients. With this lens design, we are able to vault to within 50u of the central cornea, which is nearly impossible to achieve with sclerals. Paralleling the cornea with this degree of precision yields excellent vision in the vast majority of patients. The soft skirt provides excellent centration and comfort. An acceptable lens can be achieved in two visits.

We often hear of practitioners jumping to scleral lenses for every irregular cornea they see. This is acceptable if you want to be known as a scleral lens fitter. But, when practitioners become experts at using all modalities of advanced lenses (corneal GP, hybrid, and scleral) we become true problem solvers for our patients and not one-trick ponies.

Jeffrey Sonsino is in private practice in Nashville, TN.  Georgina Reinoso is in private practice in Santo Domingo, Dominican Republic.

 

WHERE TO FIND IT:
SynergEyes, Inc. •877-SEE-2012 •synergeyes.com

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