Open Journal of Ophthalmology, 2013, 3, 54-60 Published Online August 2013 (
Is the Use of Empirically Designed Custom Soft Contact
Lenses a Good Option for Challenging Patients?
Frank Spors1*, Donald J. Egan1, Lance E. McNaughton1, Jie Shen1, Matthew J. Lampa2
1Western University of Health Sciences, College of Optometry, Pomona, USA; 2Pacific University, College of Optometry, Forest
Grove, USA.
Email: *
Received April 28th, 2013; revised May 29th, 2013; accepted June 15th, 2013
Copyright © 2013 Frank Spors et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Purpose: Reasons for the lack of success for contact lens patients range from poor fit, to discomfort or to a less than
optimum wearing schedule. This project was a preliminary investigation of customized soft toric contact lenses as an
alternative for unsuccessful contact lens patients or potential drop-outs. Methods: Fifteen healthy non-compromised,
previously unsuccessful contact lens wearing patients (13 women, 2 men) with ages from 21 to 33 years (25.1 ± 2.7
years) were the subjects for this study. They were empirically fitted with 15 astigmatic and 5 spherical customized Spe-
cialEyes soft contact lenses. Visual acuities, comfort, lens movement, and rotation were evaluated. Results: Patients
fitted with customized SpecialEyes soft contact lenses had statistically significant better visual acuities than with
Phoropter Manifest Refraction. The lenses used in this study centered well and moved no more than 1 mm upon each
blink. Lens rotation was less than 10 degrees for all toric lenses. Patients gave very positive vision and comfort ratings.
Conclusion: This preliminary study supports the application of a software program to empirically design and manufac-
ture SpecialEyes custom soft lenses based upon co rneal topographical parameters and subjective manifest refraction for
those patients who either have challenging corneal parameters, high sphero-cylindrical prescriptions, or are currently
dissatisfied with their contact lenses and are potential drop-outs.
Keywords: Soft Contact Lenses; Custom Contact Lenses; Toric Contact Lenses; Contact Lenses for Astigmatism;
Empirical Contact Lens Fitting
1. Introduction
The goal of soft contact lens application is to combine
excellent vision with overall lens comfort. In recent years
the introduction of improved materials has led to an in-
crease in the popularity of soft lenses, especially since
frequent replacement options reduce the risk of microbial
infections and the presence of lens deposits. As some-
what of a disadvantage however most frequent replace-
ment lenses are only available in a narrow range of pa-
rameters. Indeed most lenses are available in just one
diameter, one or two base curves, and in the case of as-
tigmatic designs limited cylinder power and range of axis
values exists. Although these limitations result in a sim-
plified approach to lens selection, it may not be the best
way of successfully prescribing contact lenses for pa-
tients who do not have average corneal shape values,
refractive data, or visual demands.
Up to 45% of the contact lens seeking population have
astigmatism of 0.75 D or greater [1]. However, toric soft
contact lenses remain generally underutilized as a co rrec-
tive strategy. A variety of soft toric contact lenses have
been widely available for some years, but many practi-
tioners are reluctant to incorporate them into their fitting
routines or recommend them to wearers. This is partly
due to a history of unpredictable lens orientation and
difficulty in achieving a stable fit [1]. According to the
International Survey of Contact Lens Prescribing, only
19% of prescribed daily wear soft contact lenses are toric
in design [2].
The reasons for discontinuing contact lenses have been
evaluated in a number of studies [3,4]. The most com-
monly cited reason in all of these studies is discomfort,
which accounts for between 43% and 72% of the drop-
outs. Poor vision is another important factor which is due
in part to product non-availability for high prescriptions,
and practitioner misjudgment. Prime reasons for practi-
*Corresponding a uthor.
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Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients? 55
tioner misjudgment are inappropriate lens fit and uncor-
rected astigmatism [5].
Lens reproducibility is regarded as another very im-
portant factor in the success of toric soft contact lenses,
and poor reproducibility of frequent replacement lenses
has been implicated in the underutilization of these len-
ses [6].
Selection of an initial soft contact lens base curve has
traditionally been based on central corneal curvature, as
measured by keratometry. The underlying assumption
behind this is that co rneas with steeper central radii have
greater sagittal height and, therefore, require a lens of
greater sagittal depth in the form of a steeper base curve
to optimally fit the cornea. However, previous studies
have shown that there is no strong correlation between
keratometry readings and the best-fitting soft con tact lens
[7]. Accordingly soft toric contact lens fitting, when
based on manifest refraction and keratometry alone, of-
ten presents unanticipated fitting and power errors upon
initial lens dispensing [8].
Following the standard procedure of keratometry, em-
pirical fitting success with soft toric contact lenses can be
anticipated in spherical corneas, central astigmatism, or
corneas with peripheral toricity matched with central
toricity. Considering that high and irregular peripheral
corneal toricity occurs in the majority of astigmatic pa-
tients, including empirical soft contact lens fitting based
upon more corneal topographical parameters, sagittal
height, and corneal diameter, may lead to increased fit-
ting success, better visual acuity, and fewer drop-outs
[8-10]. Incorporation of all of these parameters requires
customized soft contact lenses with varying base curves,
diameters, sagittal heights, and power values [11,12].
The purpose of this project was to evaluate Spe-
cialEyes customized soft toric contact lenses as an alter-
native for unsuccessful contact lens patients or potential
2. Methods
2.1. Subjects and Inclusion Criteria
Fifteen healthy, non-compromised, previously unsuc-
cessful contact lens wearing patients (13 women, 2 men)
with ages ranging from 21 - 33 years (25.1 ± 2.7 years)
were the subjects for this stud y. The reasons for previous
drop-outs were unsatisfactory visual acuity and/or re-
duced comfort with conventional and disposable soft
contact lenses. Refractive errors were not limited, but fell
within the range of 8.00 D to + 3.75 D sphere, and up to
3.75 D of spectacle cylinder. Expressed in rectangular
Fourier optics terms, the mean spherical equivalent was
M = 4.36 D (SD 2.66 D), and the astigmatic vector
components were J0 = 0.09 D (SD 0.74 D), and J45 =
0.04 D (SD 0.62 D). None of the participants suffered
from any eye disease or injury, nor were they taking any
medication or supplements. This research followed the
tenets of the Declaration of Helsinki, and informed con-
sent was obtained from all participants. All measure-
ments were conducted at the Health Education Center at
Western University of Health Sciences, College of Op-
2.2. Measurements and Fitting Modalities
Corneal topography data were obtained using the Med-
mont E 300 Corneal Topography System (Medmont
Pty Ltd, Nudawading, VIC, Australia). Data of interest
included tangential curvature, elevation topographical
maps, simulated keratometry values, and corneal diame-
ters, as depicted in Figure 1. In addition, the patients’
maximum plus manifest non-cycloplegic Phoropter-
refractions were measured to determine lens power val-
ues. Each patient’s best corrected high contrast visual
acuities were obtained using ETDRS letters provided by
the M&S Smart System (M&S Technologies, Inc., Niles,
IL, USA) and recorded in logarithmically-stepped Snel-
len foot notation. The examination room illumination
was 100 lu x.
Thirty eyes were fitted with custom hydrogel contact
lenses, empirically designed and manufactured by Spe-
cialEyes (Bradenton, FL, USA) based upon the submitted
topographical and refractive data.
All contact lenses were initially evaluated and subse-
quently followed -up to determine if this approach in lens
design represents a successful alternative to generic lens
designs which account for the standard office stock
available and dispensed by most eye care practitioners.
Corneal anatomical features and refraction data deter-
mined the lens parameters designed by SpecialEyes’ pro-
prietary software. From the available data the following
contact lens parameters were calculated:
Base curve
Sagittal height
2.3. Contact Lenses and Lens Material
All lenses were used as daily wear lenses. Each lens was
a customized lathe-cut design manufactured by Spe-
cialEyes from the p-GMA/HEMA hioxifilcon D material
with a water content of 54%, and a Dk value of 23 × 1011
(cm/sec)(mL02/mL/mm Hg). All lenses were designed
for a three month replacement modality. Table 1 lists the
range of contact lens parameters used in this study.
Twenty-five lenses were astigmatic, and five lenses
were spherical. All patients were fit with at least one as-
tigmatic lens. Eighteen eyes had with-the-rule astigma-
tism, three eyes had against-the-rule astigmatism, and
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Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients?
Copyright © 2013 SciRes. OJOph
Figure 1. Corneal topographical maps: (a) Tangential curvature; (b) Elevation.
Table 1. Range of SpecialEyes contact lens parameters used in this study.
Parameter Range Mean SD
Base curve 7.70 mm - 9.00 mm 8.42 mm 0.40 mm
Diameter 13.80 mm - 15.20 mm 14.54 mm 0.39 mm
Sphere power 8.00 D - +3.75 D 3.69 D 2.51 D
Cylinder power 3.25 D - 0.50 D 1.47 D 0.81 D
Central thickness 99.43 µm - 284.66 µm 120.49 µm 38.91 µm
Sagittal height 3129.87 µm - 4470.68 µm 3784.10 µm 278.73 µm
four eyes had oblique astigmatism.
SpecialEyes employs a prism ballast stabilization de-
sign for back surface toric lenses, which is depicted in
Figure 2. In general, this design is associated with a
higher visual acuity when compared to alternative stabi-
lization mechanisms [13]. To assure optimum optical
quality each of the manufactured lenses was evaluated-
prior to delivery with a Nimo TR1504 contact lens power
mapper and wavefront analyzer (Lambda-X S.A., Niv-
elles, Belgium) via the Phase-Shifting Schlieren trans-
mission method. Sample images of these measurements
are displayed in Figu re 3.
2.4. Fitting Evaluation
Lenses were allowed to settle for fifteen minutes, fol-
lowed by evaluation of centration, movement, and in the
case of astigmatic lenses, lens rotation. Fitting was
evaluated with a Haag Streit BQ 900 slit lamp utilizing
the IM 900 digital imaging system and EyeCap Version
6.2.0 software (Haag Streit AG, K oeni z, Switzerland ).
In observance of Snyders Rule the maximum rotation
permitted for a successful fit was no more than ten de-
grees [14]. High contrast visual acuity was measured
under the initial conditions, and all patients rated vision
and comfort with their lenses on a scale from 1 (not sat-
isfied) to 5 (excellent).
Fitting success was determined as indicated by the fol-
lowing parameters:
Visual Acuity: with SpecialEyes contact lenses equal
to or better than Phoropter Ma nifest Refraction.
Subjective Vision Rating: at least 4 (very satisfied) for
the majorit y of l enses, and no value of 1 (not satis fied)
for any lens.
Subjective Comfort Rating: at least 4 (very satisfied)
for the majority of lenses, and no value of 1 (not sat-
isfied) for any lens.
Lens Rotation: less than 10 degrees for astigmatic
Lens Decentration: between 0.1 mm and 1.0 mm post-
blink movement, and in ter-blink stability.
2.5. Statistical Analysis
A Wilcoxon matched-pairs signed rank test was con-
ducted for thirty eyes with Prism6 (GraphPad Software
Inc., La Jolla, USA) after not passing the Kolmogorov-
Smirnov normality test with Dallal and Wilkinson ap-
Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients? 57
Figure 2. SpecialEyes toric soft contact lens, prism ballast stabilization example: (a) Front view showing markings, toric optic
zone, and prism distribution; (b) Cross-sec t io nal view illustrating prism distribution.
Figure 3. Nimo TR 1504 images of a SpecialEyes soft toric contact lens: (a) Phase-shifting Schlieren image; (b) Wavefront
analysis of the central 6 mm optical zone of the same lens, (Images courtesy SpecialEyes).
proximation to Lilliefors’ method (P < 0.0001) [15].
The mean visual acuity values achieved with the
Phoropter Manifest Refraction and with the SpecialEyes
lenses were compared. For statistical purposes, a P value
lower than 0.05 was considered statistically significant.
3. Results
The analysis of mean visual acuity displayed in Figure 4
and Table 2 illustrates that patients fit with customized
SpecialEyes soft contact lenses had a statistically signifi-
cant better visual acuities than with Phoropter Manifest
Refraction. All p atients evaluated the contact lenses with
regards to vision and comfort and ga ve rat ings of at least 4
(very satisfied) for the majority of lenses, whereas no one
reported a val ue o f 1 (not satisfied) for any lens, as shown
in Figure 5. Judgments of lens and axis rotation as well as
movem ent upon blink a re depicted i n Figure 6. The lenses
used in thi s s tudy cente red we ll and mo ved s m oothl y over
the patients’ corneas and conjunctivas. Figure 7 shows
two representative slit lamp biomicroscopy images.
4. Discussion
The results of this preliminary study support the ap plica-
tion of a software program to empirically design and
Copyright © 2013 SciRes. OJOph
Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients?
Figure 4. Visual acuities achieved with Phoropter Manifest Refraction and SpecialEyes lenses.
Table 2. Statistical analysis of differences in visual acuities achieved with Phoropter Manifest Refraction versus SpecialEyes
Wilcoxon matched-pairs signed rank test
Treatment modality Phoropter Manifest Rx SpecialEyes
Number of values 30 30
Mean 0.9623 1.045
Std. Deviation 0.1632 0.1255
Std. Error of M ea n 0.02980 0.02291
Lower 95% CI of mean 0.9014 0.9981
Upper 95% CI of mean 1.023 1.092
P value 0.0208
Significantly different ? (P < 0. 05) Yes
One- or two-tailed P value? Two-tailed
Sum of positive, negative ranks 88.50, 16.50
Sum of signed ranks (W) 72.00
Figure 5. Subjective r atings for SpecialEyes soft contact lenses: (a) Vision; (b) Comfort.
Copyright © 2013 SciRes. OJOph
Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients? 59
Figure 6. SpecialEyes lenses observed by biomicroscopy: (a) Rotation; (b) Movement.
Figure 7. Biomicroscopy images of SpecialEyes custom soft lenses: (a) Spherical lens; (b) Astigmatic lens.
manufacture SpecialEyes custom soft lenses based upon
corneal topographical parameters and subjective manifest
refraction data for those patients who either have chal-
lenging corneal parameters, high sphero-cylindrical pre-
scriptions, or are currently dissatisfied with their contact
lenses and are potential drop-outs. Customized lens pa-
rameters, a robust stabilization mechanism for astigmatic
lenses, a comfortable hydrophilic material, in vivo pa-
rameter stability, and high reproducibility are shown here
to be important elements for successful fitting soft con-
tact lenses in challenging patients.
Lenses made from the hioxifilcon material family, as
used in this study, are known to remain saturated and
dimensionally stable on the eye resulting in excellent
visual acuity, comfort, as well as alleviation of sympto ms
and ocular surface staining associated with contact lens
related dryne ss [16].
The patients in our study reported good comfort and
vision with customized SpecialEyes soft contact lenses.
With these lenses the patients achieved statistically sig-
nificant improvements in visual acuities when compared
with Phoropter Manifest Refraction, although this dif-
ference was not clinically significant, since the visual
acuity improved less than one line. Possible explanations
for the increase in visual acuity with lenses when com-
pared to the best corrected manifest phoropter refraction
may be larger retinal image sizes in myopic patients, and
the reduction of some corneal higher order aberrations,
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Is the Use of Empirically Designed Custom Soft Contact Lenses a Good Option for Challenging Patients?
e.g. coma, due to the thickness of the hioxifilcon D con-
tact lens material [13,17].
5. Conclusions
The results of this study suggest that empirically de-
signed custom fit soft contact lenses:
Fit most refractive parameter combinations and cor-
neal profiles;
Allow fast and easy correction of high astigmatic re-
fractive errors;
Provide good patient comfort;
Reduce chair-time;
Increase the first pair fit success rate.
The virtually unlimited range of parameters with these
lenses assures availability of the optimal lens for each
patient’s condition, and may have a positive impact on
patient compliance and loyalty. A rigorous cleaning and
disinfecting regimen in combination with planned lens
replacement is necessary to maintain optical quality as
well as hydrophilicity, and to decrease the accumulation
of long term deposits on the contact lens material. It ap-
pears that a 3-month replacement cycle is appropriate for
these lathe-cut manufactured custom soft lenses.
Additional research with a larger sample of normal as
well as compromised corneas, different lens types and
materials is planned for future studies.
6. Acknowledgements
We thank SpecialEyes, especially Ms. Lindsay McCorkle,
for empirically designing and providing the customized
contact lenses used in this study.
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