Download Scleral Lenses in the Management of Keratoconus

ARTICLE
Scleral Lenses in the Management of Keratoconus
Muriel M. Schornack, O.D., and Sanjay V. Patel, M.D.
Purpose: To describe the use of Jupiter scleral lenses (Medlens Innovations, Front Royal, VA; and Essilor Contact Lenses, Inc., Dallas, TX) in the
management of keratoconus.
Methods: We performed a single-center retrospective chart review of our
initial 32 patients with keratoconus evaluated for scleral lens wear. All
patients were referred for scleral lens evaluation after exhausting other
nonsurgical options for visual correction. Diagnostic lenses were used in
the initial fitting process. If adequate fit could not be achieved with
standard lenses, custom lenses were designed in consultation with the
manufacturers’ specialists. The following measures were evaluated for
each patient: ability to tolerate and handle lenses, visual acuity with scleral
lenses, number of lenses, and visits needed to complete the fitting process.
Results: Fifty-two eyes of 32 patients were evaluated for scleral lens
wear. Of these, 12 patients (20 eyes) decided not to pursue scleral lens wear
after initial evaluation. One patient (2 eyes) abandoned the fitting process
after cataract surgery. The remaining 19 patients (30 eyes) were fit
successfully. The average number of lenses ordered per eye was 1.5. The
fitting process required an average of 2.8 visits. Standard lenses were
prescribed for 23 eyes, and custom designs were needed for 7 eyes. Median
best-corrected visual acuity improved from 20/40 (mean, 20/76) before
scleral lens fitting to 20/20 (mean, 20/30) after fitting. Follow-up ranged
from 3 to 32 months.
Conclusions: Jupiter scleral lenses provide acceptable visual acuity and
comfort in patients with keratoconus. The availability of diagnostic lenses
facilitates the fitting process.
Key Words: Keratoconus—Scleral contact lenses—Visual acuity—Ectasia.
(Eye & Contact Lens 2010;1: 39⫺44)
K
eratoconus is a noninflammatory, ectatic corneal disorder
characterized by progressive thinning and distortion of the
apical cornea. The condition is bilateral but frequently asymmetric.1 Visual acuity in patients with keratoconus may be compromised because of either irregular astigmatism or corneal scarring.2
Kennedy et al. reported that the prevalence of keratoconus was 55
per 100,000 population; they also found that the probability of
survivorship without corneal transplantation for 20 years beyond
initial diagnosis was approximately 80%.3
From the Department of Ophthalmology, Mayo Clinic, Rochester, MN.
Supported by Research to Prevent Blindness Inc., New York, NY (an
unrestricted grant to the Department of Ophthalmology, and SVP as Olga
Keith Wiess Special Scholar), and Mayo Foundation, Rochester, MN.
The authors have no financial interest in the products or manufacturers
described.
Address correspondence and reprint requests to Muriel M. Schornack,
O.D., Department of Ophthalmology, Mayo Clinic, 200 First Street, SW,
Rochester, MN 55905; e-mail: [email protected]
Accepted October 23, 2009.
DOI: 10.1097/ICL.0b013e3181c786a6
Eye & Contact Lens • Volume 36, Number 1, January 2010
Management of patients with keratoconus consists primarily of
providing optical correction to maximize visual function. In very
mild or early disease, spectacle correction or standard hydrogel or
silicone hydrogel lenses may provide adequate vision. However,
disease progression results in increasing ectasia, which gives rise
to complex optical aberrations. Rigid gas-permeable contact lenses
mask these aberrations by allowing a tear lens to form between the
contact lens and the irregular corneal surface. Zadnik et al. found
that 65% of patients who enrolled in the Collaborative Longitudinal Evaluation of Keratoconus study were wearing rigid gaspermeable lenses in one or both eyes at the time of enrollment.4
Despite their optical benefit, corneal rigid gas-permeable lenses
may not be appropriate for all patients with keratoconus. In advanced
cases, surface irregularity may increase the likelihood of significant
lens decentration or even dislocation, and some patients cannot adapt
to the lens sensation induced by standard corneal lenses. Other
patients live or work in dry or dusty environments that are not
conducive to corneal rigid gas-permeable lens wear. Piggyback lens
systems or hybrid lenses may provide adequate comfort in some of
these patients, but they also increase the complexity and cost of lens
wear and storage. In addition to presenting fitting and adaptation
challenges, corneal rigid gas-permeable lenses may be associated with
an increased risk of corneal scarring in patients with keratoconus.5–7
The use of large-diameter “contact shells” in the management of
keratoconus was initially described by Kalt in 1888,8 at approximately the same time as Mueller9 and Fick10 were describing their
experiments with blown glass shells. Manufacturing challenges
and complete lack of oxygen permeability of these early lenses
limited their use. The development of computer-assisted manufacturing processes and the introduction of gas-permeable contact
lens materials have led to a resurgence of interest in large-diameter
lens designs, and several authors have described the use of scleral
rigid gas-permeable lenses for the management of keratoconus.11–16
At Mayo Clinic, we began using Jupiter (Medlens Innovations,
Front Royal, VA; and Essilor Contact Lens, Inc., Dallas, TX)
scleral lenses in June 2006. We fit lenses by using the 18.2-mmdiameter diagnostic lens series (manufactured by Medlens Innovations), which includes standard and keratoconus designs. This
study describes our initial experience with Jupiter scleral lenses in
the management of keratoconus and highlights the relative ease,
efficiency, and efficacy of fitting these large-diameter lenses.
MATERIALS AND METHODS
During the period of this study (June 2006 through November
2008), we evaluated 209 patients for possible scleral lens wear. Of
all patients evaluated for scleral lens wear, 32 (15%) had keratoconus. All the patients with keratoconus referred to us reported
some level of dissatisfaction with vision or comfort with their current
39
M.M. Schornack and S.V. Patel
Eye & Contact Lens • Volume 36, Number 1, January 2010
FIG. 1. Scleral lens in situ on an eye with keratoconus. The lens rests
on the sclera without conjunctival blanching and vaults the cornea
from limbus to limbus. Because the lens extends into the fornices,
minimal discomfort is generated from interaction with the eyelids.
mode of correction. These patients represent the first patients with
keratoconus evaluated in Mayo Clinic’s scleral lens practice.
Because appropriate sagittal depth is more important than alignment with the central cornea in scleral lens fitting, selection of the
initial diagnostic scleral lens differs from initial lens selection for
corneal lens fitting. As of yet, no specific fitting guidelines for scleral
lenses have been validated or published. The fitting guide provided by
Medlens Innovations for Jupiter lenses suggests that the base curve of
the initial diagnostic lens should be approximately 1 diopter steeper
than the steepest corneal curve. Consultants at Essilor suggest that the
reference sphere from the elevation map generated by a corneal
topographer may be the most appropriate starting point for diagnostic
scleral lens fitting. Before fitting scleral lenses, we obtained topographic images on all patients except one (2 eyes); simulated keratometry was recorded unless the corneal surface was too irregular to
provide meaningful videokeratoscopic data (11 eyes). Reference
sphere was also recorded for all eyes for which topographic images
were obtained. We based our initial diagnostic lens selection on the
reference sphere and external observation of the profile of the anterior
corneal surface. We used 18.2-mm-diameter diagnostic lenses for all
patients in this series.
Fitting goals for scleral lenses included scleral alignment with
little or no blanching of conjunctival vasculature, complete limbal
clearance, and complete corneal clearance (Figs. 1 and 2). If the
initial diagnostic lens did not completely clear the cornea, lenses
with successively greater sagittal depth were applied until corneal
clearance was realized. If the depth of the post-lens fluid reservoir
was excessive, successively shallower lenses were applied until a
more appropriate clearance was realized. Post-lens fluid reservoir
depth between 0.15 and 0.4 mm was considered acceptable. Depth
was estimated by comparing its thickness to corneal thickness.
Once a lens with appropriate sagittal depth was identified, a spherocylindrical overrefraction was performed. All lenses were ordered
either from Medlens Innovations or Essilor Contact Lens, Inc.
Patients who decided to proceed with scleral lens fitting after
initial evaluation received individualized instruction in the care
and handling of their lenses. Each patient returned for evaluation
of vision and lens fit several hours after completing the training.
An additional follow-up visit was scheduled 2 to 4 weeks after
40
FIG. 2. Magnified view of scleral lens in situ. The scleral lens
completely clears the cornea, reducing ocular surface discomfort,
and the tear lens formed between the scleral lens and the cornea
neutralizes much of the irregular astigmatism in keratoconus (black
arrow indicates the anterior surface of the lens, white arrow indicates
the posterior surface of the lens, and line segment indicates the depth
of the post-lens fluid reservoir).
dispensing the lenses. Revised lenses were ordered as needed to
achieve optimal vision, comfort, and fit.
We assessed each patient’s ability to wear and handle the scleral
lenses comfortably, visual acuity with scleral lens correction and with
spectacle overrefraction compared with acuity with habitual correc-
FIG. 3. Distribution of monocular visual acuity with habitual refractive correction at the time of referral for scleral lens fitting (52 eyes of
32 patients with keratoconus), comparing patients who proceeded with
scleral lens fitting to those who chose not to pursue scleral lens wear.
Eye & Contact Lens • Volume 36, Number 1, 2010
Eye & Contact Lens • Volume 36, Number 1, January 2010
Scleral Lenses in the Management of Keratoconus
TABLE 1. Characteristics of Patients Who Did Not Complete the Scleral Lens Fitting Process
Patient
Age
Sex
1
28
F
2
63
F
3
71
F
Habitual
correction
Reason for scleral lens
evaluation
Eye
Spectacles
Contact lens intolerance
OS
Spectacles
Blurred vision
Corneal RGP
Contact lens intolerance
Entering visual
acuity
Simulated
keratometry
Reference
sphere
Outcome; reason for
outcome
20/60
52.12/47.62 @ 148
47.3
OD
20/40 ⫺ 2
Not available
40.3
OS
20/50 ⫹ 1
54.37/48.87 @ 122
48.6
OD
20/50 ⫺ 1
54.37/45.87 @ 086
50.8
OS
20/40 ⫺ 1
45.87/45.12 @ 034
45.2
Initial evaluation only;
good spectaclecorrected VA OD
(20/20)
Initial evaluation only;
no improvement in
visual acuity due to
lens opacity
Initial evaluation only;
handling concerns,
no improvement in
vision due to lens
opacity
Initial evaluation only;
good uncorrected
VA OD (20/20)
and handling
concerns
Initial evaluation only;
central corneal scar
limited visual
potential to 20/80,
proceeded to
transplant
Initial evaluation only;
lack of insurance
coverage
Initial evaluation only;
minimal visual
benefit
demonstrated
Initial evaluation only;
minimal visual
benefit
demonstrated
Initial evaluation only;
good comfort and
visual function with
current correction
Initial evaluation only;
good uncorrected
vision OS (20/20)
Initial evaluation only;
good spectaclecorrected vision,
handling concerns
Initial evaluation only;
minimal visual
benefit
demonstrated
Fit abandoned; had
cataract surgery
4
17
M
No correction
Contact lens intolerance
OS
20/50
49.12/45/12 @ 034
47.5
5
18
M
Spectacles
Blurred vision
OD
20/400
Not available
56.0
6
26
M
Corneal RGP
Contact lens intolerance
OD
20/30 ⫺ 1
46.75/44.75 @ 034
44.8
OS
20/30 ⫺ 1
55.12/48/87 @ 148
48.7
OD
20/25 ⫺ 1
48.12/44.87 @ 056
45.3
OS
20/20
47.37/44.87 @ 120
45.0
OD
20/20
43.75/41.00 @ 002
41.6
OS
20/20
43.50/40.50 @ 180
41.2
OD
20/50 ⫹ 1
48.25/46.00 @ 002
46.5
7
8
9
28
33
33
M
M
M
Spectacles
Spectacles
Piggyback
contact
lenses
Contact lens intolerance;
blurred vision
Contact lens intolerance;
blurred vision
10
37
M
No correction
Interest in scleral lenses
(vision and comfort
adequate in current
correction)
Interest in scleral lenses
11
42
M
Spectacles
Contact lens intolerance
12
13
49
66
M
F
Toric hydrogel
lenses
Spectacles
Contact lens intolerance;
fluctuating vision
Contact lens intolerance
OS
20/25 ⫺ 1
Not available
51.6
OD
2’/400
Not available
61.7
OD
20/25
48.00/46.12 @ 082
46.8
OS
20/20 ⫺ 1
47.87/46.62 @ 108
46.7
OD
20/30 ⫹ 1
45.37/39.75 @ 088
42.9
OS
20/20 ⫺ 1
44.37/36.87 @ 084
42.1
OD
OS
20/40
10/400
47.86/46.62 @ 068
62.37/57.87 @ 108
46.6
53.5
RGP indicates rigid gas permeable; VA, visual acuity.
tion at the time of referral, the number of lenses ordered per eye, and
the number of visits necessary to complete the fitting process.
RESULTS
A total of 32 patients (52 eyes) were evaluated for scleral lens
wear during the course of the study. At the time of presentation, 16
patients were primarily wearing spectacle correction, 8 were wearing corneal rigid gas-permeable lenses, 1 was wearing hydrogel
toric lenses, 3 were wearing piggyback systems, and 4 were
wearing no correction. Mean patient age was 39 years (range,
17–71 years) and 12 patients were women. Monocular visual
acuity with habitual correction at the time of referral ranged from
20/20 to 20/400 (Fig. 3). Average follow-up was 22.5 months
(range, 5–34 months).
© 2010 Lippincott Williams & Wilkins
After initial consultation, 12 patients (20 eyes) chose not to proceed
with the fitting process. The most common reason was a lack of visual
benefit with scleral lenses compared with the habitual correction; 9 of
the 12 patients were able to resolve 20/20 or 20/25 binocularly with
their habitual correction. Patients 2, 3, and 5 (five eyes) had either lens
or corneal opacities that precluded improvement in visual acuity with
scleral lenses. One patient cited handling concerns as the determining factor in his decision not to pursue scleral lens wear. One
patient (two eyes) had cataract surgery during the fitting process
and found that her vision was adequate with spectacles after
surgery. Characteristics of patients who were not successfully fit
with scleral lenses are summarized in Table 1. Median entrance
visual acuity of eyes considered for scleral lens wear in patients
who chose not to pursue scleral lens fitting was 20/30. Median
binocular acuity in these patients was 20/20.
41
M.M. Schornack and S.V. Patel
Eye & Contact Lens • Volume 36, Number 1, January 2010
TABLE 2. Summary of Fitting Process and Scleral Lens Design
Patient
ID
Age Sex
1
34
F
Habitual
correction
Piggyback
contact
lenses
2
43
F
Corneal
RGP
3
44
F
Spectacles
4
44
F
Spectacles
5
46
F
Spectacles
6
47
F
Piggyback
contact
lenses
Spectacles
7
8
52
61
F
F
9
20
M
10
22
M
11
23
M
12
27
M
13
30
M
Reason for scleral
lens evaluation
Fluctuating vision, OD 48.12/46.25
dryness
@ 144
OS 56.12/53.62
@ 088
Blurred and
OD 49.37/44.50
fluctuating
@ 076
vision
Contact lens
OD Not available
intolerance;
OS 54.37/48.12
blurred vision
@ 146
Contact lens
OS Not available
intolerance;
blurred vision
Poor vision
OD Not available
Corneal
RGP
18
57
M
Spectacles
19
44
M
Corneal
RGP
2
Standard
Standard
20/80
20/25
45.7
54.00
2
3
Custom
20/400
44.3
65.92
1
3
4
Standard Unable to
testb
Standard
20/200
1
49.00
1
51.37
1
40.00
OS
49.8
Contact lens
intolerance
M
1
1
52.25
Spectacles
39
52.25
48.12
2
M
17
57.7
47.7
43.25
31
Spectacles
20/40
2
15
M
Standard
42.12
Contact lens
intolerance
Work-related RGP
intolerance;
blurred vision
with spectacles
Work-related RGP
intolerance;
blurred vision
with spectacles
Contact lens
intolerance;
fluctuating
vision
Contact lens
intolerance;
fluctuating
vision
OD 61.87/51.12
@ 050
OS 52.00/46.37
@ 148
20/20
2
OD 45.00/41.87
43.4
@ 004
OS 45.50/43.50
43.6
@ 014
OD Not available Not
available
OS Not available Not
available
OS 66.5/48.12
54.8
@ 160
OD Not available
45.6
Corneal
RGP
20/70
1
Blurred vision
with spectacles
and RGPs
M
20/60
46.00
2
OD 50.62/44.37
@ 046
OS 54.37/48.87
@ 144
OD Not available
OS 44.87/41.00
@ 120
OD 46.87/44.87
@ 176
OS 47.25/47.25
@ 180
OD 53.00/45.37
@ 104
OS 62.12/50.12
@ 164
OD 49.25/42.87
@ 038
OS 48.75/45.25
@ 132
OD 54.50/49.25
@ 060
Standard
46.6
2
OS
20/40
2
50.50
49.25/48.25
@ 044
Not available
20/30
51.87
52.25
Contact lens
No
correction
intolerance
Spectacles
Contact lens
intolerance
Corneal
Contact lens
RGP
intolerance
Corneal
Recurrent apical
RGP
erosions;
contact lens
intolerance
Spectacles
Contact lens
intolerance
Standard
48.4
50.9
No
Contact lens
correction
intolerance;
blurred vision
Entrance
With scleral
(plus spectacle
overrefraction)
1
46.9
Not available
Lens
design
48.12
OS
3
Visual acuity
44.8
OD Not available
31
39
Reference
sphere
Contact lens
intolerance
14
16
Eye
Simulated
keratometry
Base
curve
of final No.
No.
lens
lenses visits
20/30 (20/20)
20/25 (20/20)
20/400a (20/20)
20/40 (Lea symbols)
20/40
Standard
20/25
Standard
20/50
20/40 (20/20)
Standard
20/30
20/25 (20/20)
Custom
20/200
20/70
Custom
20/60
20/25 ⫺ 2
3
Custom
20/400
20/60 ⫹ 2
2
3
Standard
20/50
20/25 ⫺ 1
46.00
1
2
Standard
20/50
20/20
55.7
50.50
1
3
Standard
20/30
20/30
44.9
45.12
1
3
Standard
20/25
20/20
47.8
48.12
1
Standard
20/50
20/20
48.2
43.2
46.87
46.87
2
2
3
Standard
Standard
20/40
20/20
20/20
20/20
45.3
46.87
1
2
Standard
20/20
20/20
47.0
48.12
1
Standard
20/20
20/20
50.8
48.12
2
Standard
20/50
20/20
56.1
61.00
3
Custom
20/150
20/70
46.2
49.87
1
Standard
20/20
20/20
46.6
49.12
1
Standard
20/20
20/25
48.2
49.00
1
2
Standard
20/30
57.7
49.00
2
3
Custom
20/50
20/40
49.2
43.50
2
Custom
20/40
20/30
3
3
4
3
20/25
20/25 (20/20)
a
Unilateral scleral lens fit, high myopia in the right eye, intentional undercorrection in the scleral lens reduced the risk of spectacle-induced
aniseikonia.
b
Down syndrome, unable to measure visual acuity with Snellen chart, Lea chart not available at initial examination.
RGP indicates rigid gas permeable.
42
Eye & Contact Lens • Volume 36, Number 1, 2010
Eye & Contact Lens • Volume 36, Number 1, January 2010
FIG. 4. Comparison of visual acuity with habitual correction at the
time of presentation to visual acuity with scleral lenses in patients
who were successfully fit.
The remaining 19 patients (30 eyes) were successfully fit with
Jupiter scleral lenses. Demographic characteristics, information on
habitual refractive correction at the time of referral, topographic
indices, and a summary of the fitting process for these patients are
summarized in Table 2. Acceptable scleral lens fit was achieved in
an average of 2.8 visits (range, 2– 4 visits). Fitting was completed
in 2 visits for 5 patients, in 3 visits for 12 patients, and in 4 visits
for 2 patients. On average, 1.5 lenses (range, 1–3) were ordered for
each eye during the fitting process. The first lens ordered was the
lens prescribed for 17 eyes (57%), the second lens ordered was the
lens prescribed for 12 eyes (40%), and the third lens ordered was
the lens prescribed for 1 eye. Standard lens designs were prescribed for 23 eyes (77%) whereas 7 eyes required custom designs
to optimize the scleral lens fit. Median monocular entrance visual
acuity of eyes of patients who were successfully fit with scleral
lenses was 20/40. Median binocular acuity at initial examination
was 20/25. After scleral lens fitting, visual acuity improved by an
average of 2.9 lines, and median visual acuity was 20/20 (Fig. 4).
DISCUSSION
Awareness of the potential benefits of large-diameter rigid
gas-permeable lenses for patients with a wide range of ocular
conditions has been steadily increasing during the past several
years. Management of corneal ectasia with scleral contact lenses
has been described in several studies.11,12,15,17,18 Pullum and Buckley17
reported a 60% overall success rate in a group of 530 patients fit
with scleral lenses for a variety of diagnoses, more than half of
which had keratoconus. Segal et al.18 fitted 48 patients (66 eyes),
of whom 75% had keratoconus, with an overall success rate of
90%. Visser et al.19 described the use of the ProCornea lens and
reported that 50% of patients fitted with that particular scleral
design had keratoconus. As noted earlier, 15% of patients referred
to us for scleral lens evaluation had keratoconus. We successfully
fitted 59% of all patients with keratoconus referred to us for scleral
lens evaluation. All but one of our patients who ultimately chose
not to pursue scleral lens wear decided to continue with their
habitual correction immediately after initial scleral lens evaluation;
the majority (9 of 12, 75%) of these patients were able to resolve
20/25 (Snellen) or better binocularly with their habitual correction.
We were able to provide acceptable vision and comfort with scleral
lenses in 95% (19 of 20) patients who chose to proceed with the fitting
process after initial evaluation.
Corneal rigid gas-permeable lenses have long been assumed to
provide the best possible visual acuity in patients with keratoco© 2010 Lippincott Williams & Wilkins
Scleral Lenses in the Management of Keratoconus
nus. In severe keratoconus, the irregularity of the anterior corneal
surface can make it difficult to achieve reasonable lens centration
and stability with corneal lenses. A retrospective study by Salam et
al.20 indicated that scleral contact lenses provide visual acuity that
was comparable with that attained with corneal lenses in patients
with moderate to severe keratoconus. Significant improvement in
visual acuity was reported with scleral lenses in patients with
keratoconus in the study by Visser et al.,21 and Segal et al.18
reported that 91% of patients with keratoconus achieved 20/40 or
better acuity with scleral lenses. Similarly, 87% of our patients
achieved 20/40 or better Snellen acuity with scleral lenses.
The perception that fitting large-diameter lenses is time consuming, costly, and complex may be limiting their widespread use at
present. Our experience suggests that fitting scleral lenses with the
use of standard diagnostic trial sets may be similar to, or even
easier than, fitting corneal or corneoscleral rigid lenses. Although
keratoconus can cause considerable corneal irregularity, our ability
to successfully fit scleral lenses with regular peripheral parameters
suggests that the contour of scleral tissue may be less affected by
the disease. Fitting scleral lenses avoids the challenges associated
with attempting to balance lenses on highly irregular tissue and to
instead align the lenses with relatively normal scleral tissue.
Advanced imaging technology can certainly be used to design
scleral lenses,22 but we were able to successfully fit Jupiter lenses
by standard diagnostic lenses. We habitually collect topographic
data on patients with keratoconus before any contact lens fitting;
therefore, we did obtain topography on patients in this study.
However, we did not observe a close association between any
single topographic index and the base curve of the final scleral lens
prescribed. It is likely that we could have successfully fit Jupiter
scleral lenses with diagnostic lenses in the absence of any topographic data. Diagnostic lens fitting carries the added advantage of
allowing the patient to experience the sensation and vision that can
be expected with scleral lenses before committing to the complete
fitting process. The majority (77%) of the lenses that we prescribed
were standard designs, although we used consultative services
provided by the lens manufacturers to assist us in designing
custom lenses when necessary. Base curve radius and diameter can
be adjusted, as can radius of curvature and diameter of any of the
four peripheral curves, to create appropriate sagittal depth across
the entire cornea and limbus.
The wide variety of corneal lens options (rigid gas-permeable
lenses, hybrid lenses, custom hydrogels, and piggyback systems)
allow for adequate management of most cases of keratoconus, and
these options may certainly be explored before considering scleral
lenses. However, some patients with keratoconus do not achieve
adequate vision or comfort with corneal contact lenses. Furthermore, one patient in our series experienced recurrent apical erosions with corneal lenses. In situations such as this, scleral lenses
may be advantageous because they vault the cornea and allow the
entire corneal epithelium to be bathed with fluid. Scleral lenses can
be used to manage ocular surface diseases such as neurotrophic
keratitis12 or graft versus host disease.23 The stability of scleral
lenses along with their generous optical zone diameter (8.2– 8.6
mm) allow them to provide consistent vision; lens awareness is
minimized because the conjunctival tissue on which scleral lenses
rest is less sensitive compared with corneal tissue, and lid interaction is minimized because the lenses extend well into the
fornices. The Collaborative Longitudinal Evaluation of Keratoco43
M.M. Schornack and S.V. Patel
nus study found that contact lens wear was associated with an
increased risk of corneal scarring in patients with keratoconus
(odds ratio, 2.50).6 Because scleral lenses do not touch the cornea,
the risk of apical scarring could potentially be less with scleral
lenses than with traditional corneal lenses. This intriguing possibility has not been formally studied but may warrant further
investigation.
Corneal contact lens intolerance is one of the primary indications for keratoplasty in patients with keratoconus.24 The option of
fitting scleral lenses may defer the need for keratoplasty in patients
who are intolerant to traditional contact lens designs and who do
not have visually significant corneal scarring. Although penetrating keratoplasty has a 93% to 96% initial success rate,24 many
patients still require rigid contact lenses for their best vision, and
complications can occur including graft rejection and graft failure
in approximately 20% and 10% of eyes, respectively, over 15 years.25
Furthermore, ectasia can recur in 6% to 11% of eyes receiving a
penetrating keratoplasty for keratoconus,26,27 frequently requiring
repeat keratoplasty in this young group of patients.28 Scleral lenses
can provide good vision and comfort in many contact lens-intolerant
patients and may delay the need for primary or repeat surgical
intervention in this relatively young group of patients.
At present, there is considerable confusion regarding the terminology used to describe large-diameter lenses. We have suggested
that lenses be described based on their fitting characteristics rather
than their overall diameter. Lenses that do not extend beyond the
limbus are generally considered to be “corneal” lenses. Lenses that
extend past the limbus but rest on the cornea could be referred to
as “corneoscleral” lenses. Lenses that are supported entirely by the
sclera, completely clear the limbus, and measurably vault the cornea
could be defined as “scleral” lenses.23 By these definitions, the lenses
described in this study would be defined as scleral lenses.
CONCLUSIONS
Scleral lenses can provide good vision and comfort for patients
with keratoconus. Our early experience with the Jupiter lenses
suggests that a diagnostic fitting process is reasonably efficient.
The lenses may delay the need for keratoplasty in patients who
have exhausted other options for visual correction. Therefore, we
consider Jupiter scleral lenses an excellent option for patients with
keratoconus who achieve inadequate outcomes with spectacles or
corneal contact lenses.
ACKNOWLEDGMENTS
The authors thank Dr. Keith Baratz for his assistance in the
preparation of this manuscript.
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