Download Clinical Analysis of Scleral Lenses on Regular Corneas

Clinical Analysis of Scleral Lenses on Regular Corneas
Stephanie Ramdass, OD, MS; Chad Rosen OD, FAAO; Craig Norman, FCLSA;
Robert Buckingham, OD, PhD, FAAO
Introduction
The use of scleral lenses is becoming a mainstay for
many practitioners when dealing with irregular corneas
(Figure 1). Refractive error management in patients
suffering from primary and secondary corneal ectasia
is often most successful when the entire irregularity is
vaulted over with the contact lens.
In ocular surface diseases such as severe dry eye and
Steven’s Johnsons Syndrome, the constant bath of
liquid against the compromised corneal surface can
provide significant relief of associated discomfort and
painful symptoms.
As this use continues to expand, we are also seeing a
trend of practitioners questioning whether or not scleral
lenses can/should be used on normal corneas.
In subjects with normal keratometric measurements
and corneal surfaces devoid of any observed
pathology (Figure 2), could scleral lens wear be
successfully implemented?
The purpose of this study was to assess the results of
vision, comfort, and fit on regular corneas in a clinical
setting among a cohort of young adults.
Figure 2
Figure 1
Methods
Thirty-Five (35) subjects who met the Ferris State
University’s Institutional Review Board approved study
protocol criteria were enrolled. A minimum of four office
visits were required (Figure 3). During the initial fitting visit,
a diagnostic fit of both the right and left eye was carried out
according to manufacturer recommended guidelines using
the Valley Contax Custom Stable design. Lenses were
ordered and dispensed to each subject with all instructions,
solutions, and tools provided (Figure 4).
Figure 3
If successful scleral lens wear remained after 1-week of
daily wear up to 10 hours a day, subjects were instructed to
continue with lens wear for an additional 3 weeks.
Satisfaction surveys were completed by each subject at
each follow-up visit.
At the 1-month follow-up, scleral
lenses were removed in office, and the cornea and
conjunctival tissues were stained using fluorescein and
lissamine green ocular stain, respectively.
Figure 4
Results
Seventy-seven (77) percent of subjects (age range 19
– 37 years old) achieved a logMAR visual acuity of 0.2
or better and successfully wore their scleral lenses for
up to 16 hours a day. Eight (8) subjects discontinued
for various reasons unrelated to adverse productrelated events.
Compression of fine conjunctival vessels observed
during the original fitting process (Figure 6) was a
good clinical indicator that a modification of diagnostic
parameters of the scleral landing zone was necessary
(Chart 3). Only mild compression was observed for the
majority of subjects at the end of the study period.
Clinically Present Toricity
On average, only one refit per eye was required before
contact lens parameters were finalized. In order to
obtain a successful fit, with respect to vision, fit, and
comfort, modifications were effectively incorporated as
recommended by consultation (Table 1).
Chart 1
Figure 5
Scleral Lens Centration
Figure 6
Figure 5
Chart 2
Table 1
Scleral Landing Zone
To optimize visual acuity, front toric powered scleral
lenses were available for order and remained stable on
eye to allow for clear vision throughout wear (Figure 5).
A clinically significant shift towards against-the-rule
final contact lens powers was observed (Chart 1).
Whether the known decentration of scleral lenses on
eye due to the scleral anatomy plays a role for this
observation remains under investigation by the
authors. (Chart 2).
Figure 7
While there was no corneal staining observed during
the one month follow-up visit, mild conjunctival tissue
staining was seen, greatest in the horizontal rather
than vertical meridian (Figure 7).
Chart 3
Discussion & Conclusion
The subject demographic for the study consisted of
young adults who had high visual demands at
distance, intermediate, and near. All of these subjects
were accustomed to excellent visual acuity.
This particular scleral lens design was easily
customizable to result in an over 77% success rate
with respect to vision, fit and comfort of the bilaterally
fit contact lenses. The majority of subjects were
satisfied overall with the use scleral lens use, most
Overall Subject Satisfaction Survey
Chart 4
citing extra time for care and handling the modality as
the main reason for any dissatisfaction (Chart 4).
From this 1 month study, the authors conclude that
while irregular corneas are the main platform for
scleral lens use, regular eyes can benefit from the
comfort and vision that these lenses provide as well.
Further investigation is warranted.
The authors would like to thank Valley Contax for providing an unrestricted
educational grant for the completion of this study.