Cost effectiveness of the type II Boston keratoprosthesis

Article (PDF Available)inEye (London, England) 25(3):342-9 · December 2010with37 Reads
DOI: 10.1038/eye.2010.197 · Source: PubMed
Despite demonstrated cost effectiveness, not all corneal disorders are amenable to type I Boston keratoprosthesis (KPro) implantation. This includes patients with autoimmune diseases, such as Stevens-Johnson syndrome/toxic epidermal necrolysis. Type II KPro is implanted through the eyelids in severe dry eye and cicatricial diseases, and its cost effectiveness was sought. In a retrospective chart review, 29 patients who underwent type II KPro surgery at the Massachusetts Eye and Ear Infirmary between the years 2000 and 2009 were identified. A total of 11 patients had 5-year follow-up data. Average cost effectiveness was determined by cost-utility analysis, comparing type II KPro surgery with no further intervention. Using the current parameters, the cost utility of KPro from third-party insurer (Medicare) perspective was 63,196 $/quality-adjusted life year . Efforts to refer those less likely to benefit from traditional corneal transplantation or type I KPro, for type II KPro surgery, may decrease both patient and societal costs.
Cost effectiveness of
the type II Boston
JD Ament, TP Stryjewski, S Pujari, S Siddique,
GN Papaliodis, J Chodosh and CH Dohlman
Purpose Despite demonstrated cost
effectiveness, not all corneal disorders are
amenable to type I Boston keratoprosthesis
(KPro) implantation. This includes patients
with autoimmune diseases, such as
Stevens–Johnson syndrome/toxic epidermal
necrolysis. Type II KPro is implanted through
the eyelids in severe dry eye and cicatricial
diseases, and its cost effectiveness was sought.
Patients and methods In a retrospective chart
review, 29 patients who underwent type II
KPro surgery at the Massachusetts Eye and Ear
Infirmary between the years 2000 and 2009
were identified. A total of 11 patients had
5-year follow-up data. Average cost
effectiveness was determined by cost-utility
analysis, comparing type II KPro surgery with
no further intervention.
Results Using the current parameters, the
cost utility of KPro from third-party insurer
(Medicare) perspective was 63 196 $/quality-
adjusted life year.
Conclusion Efforts to refer those less likely to
benefit from traditional corneal
transplantation or type I KPro, for type II KPro
surgery, may decrease both patient and
societal costs.
Eye (2011) 25, 342–349; doi:10.1038/eye.2010.197;
published online 24 December 2010
Keywords: decision analysis; cost utility; cost
effectiveness; keratoprosthesis; autoimmune
Type I Boston keratoprosthesis (KPro) has
recently been shown to be a highly cost-effective
medical intervention at 16 140 $/quality-
adjusted life years (QALYs).
However, not all
corneal diseases are amenable to or appropriate
for type I implantation. Patients with
autoimmune diseases, such as Stevens–Johnson
syndrome/toxic epidermal necrolysis and
mucous membrane pemphigoid have severe
ocular surface diseases where destruction of the
corneal epithelial stem cells located at the
corneal limbus results in conjunctival invasion,
corneal neovascularization, chronic
inflammation, and stromal scarring.
end-stage cases, the ocular surface becomes
completely dry and the fornices become
obliterated. Corneal transplantation and type I
KPro, in such cases, are almost inevitably
associated with a poor prognosis.
quality of life is appreciably affected, often
experiencing considerable, if not complete, loss
of vision and numerous comorbidities. Because
of the destructive nature of these conditions,
there have been few reports on the use
of KPro surgery for the treatment of
autoimmune diseases.
In contrast, several
manuscripts have described the modified
osteoodontokeratoprosthesis as efficacious in
this patient population.
For many, this
represents the gold standard for severe ocular
surface disease. Nevertheless, the morbidity
and postoperative complications associated
with this lengthy, two-stage procedure,
the possibility for a more simplistic and
pragmatic KPro cannot be ignored, especially as
recent modifications to the type II design and
postoperative management of patients have led
to improved clinical outcomes.
To determine cost effectiveness by way of
cost-utility analysis (CUA), the perceived value
of an intervention or health state is taken into
account. Utilities on a scale from 0 to 1 are
generated, most commonly by the time trade-off
and these are used to determine
overall benefit. Benefit is measured in terms of
To our knowledge, no CUA has been
performed on the use of the type II Boston KPro.
It is the intention of this study to objectively
assess the (1) comparative effectiveness (gain in
QALYs) and (2) average cost effectiveness
(compared with no further treatment or current
Received: 4 May 2010
Accepted in revised form:
8 November 2010
Published online:
24 December 2010
This work was presented as
a poster at the World
Cornea Congress Meeting
in Boston, April 2010.
Department of
Massachusetts Eye and Ear
Infirmary, Harvard Medical
School, Boston, MA, USA
Correspondence: JD Ament,
Department of
Massachusetts Eye and Ear
Infirmary, Harvard Medical
School, 243 Charles Street,
Boston, MA, 02114-4724,
Tel: þ 1 617 721 4673;
Fax: þ 1 617 573 4300.
E-mail: jaredament@
Eye (2011) 25, 342–349
& 2011 Macmillan Publishers Limited All rights reserved 0950-222X/11
visual state) of the type II Boston KPro procedure for the
treatment of severe corneal disease and blindness.
Patients and methods
Boston KPro type II
Type II Boston KPro was developed at the Massachusetts
Eye and Ear Infirmary.
As seen in Figures 1 and 2, it is a
collar button shaped polymethylmethacrylate device
consisting of two curved plates that is implanted through
the eyelids in severe dry eye and cicatricial diseases.
Type II Boston KPro is performed far less than type I, and
is reserved for near-hopeless cases with severe
destruction of the ocular surface.
In a retrospective cohort study chart review, 29 patients
who underwent type II KPro surgery at the Massachusetts
Eye and Ear Infirmary between the years 2000 and 2009
were identified. Patients had to have a minimum of 5 years
of visual acuity follow-up data recorded. Patients receiving
type II KPro were in the worst prognostic groups, such as
autoimmune diseases and chemical burns. A total of 11
patients had a minimum of 5 years of follow-up and were
included in the study.
Patient characteristics with underlying diagnoses
before KPro surgery are given in Table 1. A complete
ophthalmic exam was performed before KPro surgery.
Median preoperative best-corrected visual acuity (BCVA)
in the treated eye was logMAR 2.3
0.7 (Snellen
equivalent HM). Visual acuity values were normally
distributed per Shapiro–Wilk testing. We certify that all
the applicable institutional and governmental
regulations concerning the ethical use of human
volunteers were followed during this research.
Decision analysis
Average cost effectiveness was determined, comparing
type II KPro surgery with no further intervention (the
current visual state). Complications and additional
procedures were incorporated into an expected-value
Figure 1 The type II Boston keratoprosthesis. The front plate of
the keratoprosthesis is shown assembled ex vivo.
Figure 2 The clinical appearance of the type II Boston
keratoprosthesis. The front plate of the keratoprosthesis is
shown implanted through the eyelid of a patient with a history
of Steven–Johnson’s Syndrome.
Table 1 Characteristics of type II Boston KPro patients
included in this study
Characteristic Amount Qualifier
Patients n ¼ 11
Gender Male ¼ 6;
female ¼ 5
Age Mean ¼ 66 years Range ¼ 37–86 years
Diagnostic group
n ¼ 6 54.5%
Ocular cicatricial
n ¼ 4 36.4%
Chemical burns n ¼ 1 9.0%
Abbreviation: Kpro, keratoprosthesis.
Type II Boston keratoprosthesis
JD Ament et al
decision tree. A list of the most common postoperative
complications and treatments are given in Table 2.
To make cost-utility calculations, several model
assumptions were made.
In our sample, 5-year anatomical retention was 72.7%.
(1) The time frame chosen for the CUA was 5 years
because of presumed quiescence of disease at this
postoperative time; (2) a yearly KPro implant survival
probability of 93.5% was conservatively interpolated
from the data; (3) BCVA preoperatively and at 5 years
postoperatively was utilized to calculate incremental
utilities; (4) the average incremental utility of the 5-year
cohort represented that of the entire sample; (5) the mean
patient age was 66, and we postulated that this was
representative of this population.
Utility assessment
utility assessment in the CUA. The mean (
preoperative utility value was 0.391 (
0.1.36), increasing to
0.568 (
0.224) at 5 years postoperatively. Decreases in
vision were accounted for by incorporating negative
utilities into the mean incremental utility calculation. The
mean incremental utility in our study population at 5 years
was 0.177. The total QALY gain (comparative effectiveness)
was also determined by multiplying the years of utility
gain by years of benefit duration and comparing it with the
preoperative utility (quality of life) state.
Identification of costs
The costs for the KPro type II device, surgical procedure,
hospitalization, and follow-up management were
obtained from the Massachusetts Eye and Ear
Infirmary CPT diagnosis and procedure codes. The CUA
was conducted based on the Medicare reimbursement
rates in 2009. Ophthalmologic visits were conducted
every 3 months for the first year, followed by every 6
months over the second year, and then annually.
Maintenance costs included medications and patient
travel. An overview of all costs is given in Table 3.
The expected-value decision tree is illustrated in
Figure 3. Future costs, such as follow-up visits and
possible complications requiring procedures, are
weighted based on normal clinical practice and rates
observed in our sample (refer to Table 2). Total costs were
calculated by the summation of initial costs with
appropriately discounted future costs. Discounted future
costs included inevitable costs and the average of
weighted probable/possible future costs.
There is a consensus that both utilities and costs should be
discounted in health care economics analyses. We decided
that the commonly used 3% discount rate was appropriate.
Calculation of QALYs
The QALYs for the 5-year period was calculated using
the following formula:
ð1 þ d
where t is the yearly transplant survival rate (0.935), u is
the average incremental utility (0.177), and d
is the
discounting rate for QALYs (3%).
Table 2 Postoperative complications and procedures over 5 years for type II Boston KPro recipients in this study
Complication/procedure No. of patients No. of treatments Percentage of total cohort
(based on treatment)
Retroprosthetic membranes 5 7 YAGs 63.6%
1 membranectomy 9.1%
Corneal leak 6 7 revisions 63.6%
Inflammation 6 7 kenalog injections 63.6%
High IOP 7 7 Ahmed valves 63.6%
Skin overgrowth 3 4 skin revisions 36.4%
Decrease in visual acuity 2 2 revisions 18.2%
Necrosis 1 2 revisions 18.2%
Systemic immunosuppressive therapy 3 2 systemic steroids 18.2%
1 alkylating agent 9.1%
1 antimetabolites 9.1%
Retinal detachment 3 1 PPV þ silicone oil 9.1%
Endophthalmitis (infectious) 1 1 IV vanc. 9.1%
1 intraocular vanc. 9.1%
1 amphotericin B 9.1%
Cellulitis 1 1 medical regimen 9.1%
Tarsorrhaphy 1 1 surgery 9.1%
KPro extrusion 3 1 replacement 9.1%
Abbreviations: IOP, intraocular pressure; Kpro, keratoprosthesis; PPV, pars plana vitrectomy; vanc, vancomycin; YAG, yttrium aluminium garnet.
Type II Boston keratoprosthesis
JD Ament et al
Calculation of cost
The equation for the total discounted cost associated with
KPro surgery is:
$11 932 þ
ð1 þ d
ð1 þ d
ð1 þ d
ð1 þ d
An initial cost that was incurred at or immediately
before or following the time of surgery was not
discounted. Costs paid for over the initial year alone
were discounted accordingly as were costs paid for
throughout the entire time period. In the equation,
x represents the year of follow-up and d
is the
discounted rate for costs (3%).
Sensitivity analysis
The model was assessed using a univariate sensitivity
analysis (Table 4.). The relevant parameters included
utility value, retention rate, discounting rate for QALYs,
and discounting rate for costs. Each parameter was
varied at fixed intervals individually.
Median preoperative BCVA in the treated eye was
logMAR 2.3
0.7 (Snellen equivalent HM). At 5 years
postoperatively, the median BCVA increased to logMAR
1.17 (Snellen equivalent of 20/400). A total
discounted incremental QALY gain of 0.668 was obtained
for type II KPro. This correlates with a conferred QALY
gain (or improvement in quality of life) of 8.7% for the
average patient. The total discounted cost associated
with this utility equaled $42 215. Using the current
parameters, the cost utility of KPro from third-party
insurer (Medicare) perspective was 63 196 $/QALY.
The univariate sensitivity analysis resulted in a range
of incremental cost-effectiveness ratios from 52 078 to
83 871 $/QALY.
As noted in the paper by Ament et al., describing the
cost effectiveness of type I Boston KPro, the commonly
cited guideline considers interventions costing below
20 000 $/QALY as highly cost effective and interventions
costing more than 100 000 $/QALY as not cost effective.
The UK National Institute for Health and Clinical
Excellence (NICE) uses 60 000 $/QALY to define
cost-effective treatments.
It is nevertheless recognized
that these benchmarks and the unit $/QALY, as a
measure of value in medicine, are inherently limited.
Indeed, insurance companies and national health boards
often rebuff reimbursement below these guidelines, fund
beyond them, or develop novel pricing arrangements
to expand access of otherwise less cost effective
Various cost-effective values
($/QALY) for several medical interventions are
illustrated in Table 5.
In this analysis, only patients with 5 years of follow-up
data were included. Although the 5-year sample was
small, it was determined that 2- to 3-year follow-up was
insufficient for this population. Based on anecdotal
evidence, severe complications remain a concern well
after the 2-year postoperative period in autoimmune
patients undergoing type II KPro surgery. This is unlike
type I KPro, in which visual gains can ostensibly be
maintained almost indefinitely. Despite this, it is
important to note that those patients considered eligible
Table 3 2010 Medicare reimbursement schedule associated
with Boston Kpro type II
Item or Service CPT code Cost (USD)
Evaluation 92 004 100
KPro surgery (surgeon fee) 65 770 1401
Facility fee þ cornea F 10 431
ECCE without IOL
66 984 896
Glaucoma shunt
66 180 1577
67 880 618
Follow-up visit 99 211 or 99 212 200 per year
Antibiotic medications
F 600/year
medications (mycophenolate
F 16400/year
Patient travel F 100/year
Procedures related to complications
YAG 67 031 333
Membranectomy 65 865 1223
Kenalog injection 67 500 147
Shunt revision
66 185 1837
Silicone oil
67 042 1417
67 036 1408
Iris repair 66 680 919
Strabismus surgery 67 331 1967
65 810/66 250/66 020 3000
Abbreviations: CPT, current procedural terminology; IOL, intra-ocular lens;
Kpro, keratoprosthesis; moxi, moxifloxacin; pf, prednisolone acetate 1%;
USD, United States Dollars; vanc, vancomycin.
Some procedures (ie, vitrectomy, silicone oil injection, cost of KPro, and
anesthesia) are bundled into KPro or facility fee, and additional
procedures at the time of surgery are reimbursed at 50%.
Vancomycin, prednisolone acetate 1%, moxifloxacinFthe standard
postoperative regimen.
Infectious endophthalmitis management in type II KPro patients usually
requires the operating room, tarsorrhaphy revision, paracentesis of the
eye for culture, injection of vancomycin 1 mg, ceftazidime 2.25 mg, and
amphotericin B 5 mcg.
Type II Boston keratoprosthesis
JD Ament et al
for type II KPro implantation typically experience severe,
debilitating sequellae of their underlying disease process,
and may perceive a limited and transient 2-year
improvement, irrespective of the complication rates and
risks, as significant, thereby possessing inherent utility.
Indeed, 16 patients had complete 2 years of follow-up
and, on average, improved from HM vision to 20/70. The
average incremental utility increase for this cohort was
exceedingly high at 0.278. This, when compared with a
0.177 average incremental utility increase in our 5-year
cohort, represents a 57% increase in average utility
change. Reassessing 2-year costs and conducting the
appropriate cost-utility calculations yield a cost-effective
value of 31 719 $/QALY for this 2-year sample. These
markedly disparate values illustrate that a dramatic
change occurs in type II KPro population after the 2-year
postoperative period. Although physiologic and
pathologic processes need to be further elucidated, it is
noteworthy that the cost-effective curve, as it relates to
visual acuity, appears to be non-linear. Worsening vision
and the associated substantial decrease in incremental
utility disproportionately affect the cost-effective
calculation as compared with only moderate increases in
costs. Furthermore, vision changes from HM to 20/400,
for example, are associated with a greater utility than,
say, improvement from 20/200 to 20/20.
Despite the limited sample, the original 5-year study
cohort demonstrated remarkable improvement in
Figure 3 Expected value decision tree for the type II Boston keratoprosthesisFpreoperative, perioperative, and postoperative
management. Decision tree is broken down into initial, inevitable, probable, and possible costs. Costs are reported on the basis
of the 2010 allowable reimbursement from Medicare. Probability of occurrence is displayed below the decision/cost item.
A single asterisk indicates costs that require appropriate discounting. Discounting can occur over some or all of the years being
assessed in this study, depending on need and utilization of the service. Furthermore, in some instances, the cost changes after the
initial year of use.
Table 4 Univariate sensitivity analysis of the cost-utility analysis for type II Boston Kpro
Variable adjustment
cost yield
Yearly Boston Kpro
survival probability
utility value
Discount rate for QALY Discount rate for costs
0.842 0.160 0.05 0.01
Current 0.935 0.177 0.03 0.03
1.000 0.194 0.01 0.05
Range ($/QALY) 52 078–83 871 57 587–69 824 59 714–66 595 60 001–66 741
Abbreviations: Kpro, keratoprosthesis; QALY, quality-adjusted life year.
Variables are changed by 10% from the current values.
Type II Boston keratoprosthesis
JD Ament et al
median visual acuity within 5 years from HM to 20/400
for a moderately cost-effective value of 63 196 $/QALY.
Though optimistic for suggesting possible expansion of
type II KPro for the management of patients with severe
autoimmune ophthalmic conditions, the complexities
of postoperative management should not be
underestimated. Consequently, the limitations of this
analysis require proper evaluation. Patients undergoing
type II KPro surgery must commit to a twice-daily
regimen of antibiotic eye drops for life, sometimes take
toxic and expensive systemic immunosuppressive drugs,
be willing to accept the cosmetic burden of the device,
and be prepared for life-long follow-up with an
experienced type II KPro surgeon. These requirements
may be burdensome for some patients and therefore
represent disutilities of the device not accounted for in
this retrospective analysis. It is possible that the 0.668
QALYs that we observed would decrease in light of these
disutilities and that the ultimate cost effectiveness of the
device would be diminished. The lack of a validated
testing mechanism to assess patient satisfaction and
preferences postoperatively limits this and other
cost-effective analyses.
Additional limitations of this analysis were its
restriction to one location and the lack of available cost-
utility literature to directly compare type II KPro with the
modified OOKPFthe latter being, arguably, the accepted
standard of care outside the USA for this patient
population. Nonetheless, the authors felt that astype II
KPro is performed so infrequently and without adequate
standardization outside of MEEI that including external
type II KPro data into this analysis would have injected
incalculable variation. With respect to the OOKP, only
one study noted the cost of rehabilitating end-stage
ocular surface disease with OOKP surgery (13 661
pounds or 21 786 USD).
A case report by Geerling et al.
did demonstrate an overall cost savings with the OOKP
of B7400 USD over 2 years. However, both of these only
examined costs and savings of the OOKP, and did not
include formal cost-utility analyses. Review of the
literature suggests that no such analysis exists, making
appropriate comparisons impossible at this time. Given
the lack of comparative data and a large multicentered
sample, external validity is limited, and it is difficult to
determine whether the cost effectiveness of type II KPro
will decrease or increase ,as it becomes more utilized in
the clinical setting.
Excluded from this cost analysis is a consideration of
the costs incurred before type II KPro implantation. Of
the 11 patients included in this analysis, 4 underwent
previous penetrating keratoplasty, 3 underwent type I
KPro implantation once, and 1 underwent type I KPro
implantation twice, all of which failed. Additionally,
seven patients had glaucoma valves in place at the
time of surgery. In contrast, expensive systemic
immunosuppressive therapies were assumed to be
continued for the entire 5 years and may represent an
overestimation of costs. Furthermore, a significant source
of additional cost for type II KPro lies in the high
probability of revision and/or replacement. This could
be greatly mitigated by improving device design and
biocompatibility, and exemplifies the need to revisit this
analysis in the future. Taking the risks, complications,
and morbidity associated with type II KPro into account,
efforts to refer patients who are less likely to benefit from
traditional corneal transplantation or type I KPro may be
helpful in decreasing both the ultimate personal and
societal cost of surgical intervention in these patients, as
evidenced by the multiple, failed procedures that occur
in this population.
Table 5 Cost utility of various medical interventions in the US,
adjusted to 2010 US dollars
Intervention (ophthalmology) Cost in
Initial cataract surgery
Second eye cataract surgery
Penetrating keratoplasty
12 194
Boston Kpro type I
16 140
Boston Kpro type II (submitted paper) 63 196
Photodynamic therapy for subfoveal choroidal neovascularization with
20/40 initial vision 104 158
20/200 initial vision 208 966
Intervention (other)
TKR (high-risk patients)
28 381
Antibiotic impregnated cement
compared with normal cement during hip
37 595
Coronary bypass surgery for occluded LAD
44 113
Chemoprophylaxis after occupational
exposure to HIV
49 036
Primary pediatric heart transplant
52 417
Renal transplantation (in Greece)
64 966
Incremental cost-utility ratio for TKR vs
unicompartmental knee arthroplasty
65 979
Total hip arthroplasty (best/worst case)
6353/110 484
Magnetic resonance imaging for equivocal
neurologic symptoms
134 742
Prophylactic hip fixation to prevent future
contralateral hip fracture
142 795
1 day of chemoprophylaxis before receiving
dental work for patients with prosthetic
696 692
Abbreviations: ARMD, age related macular degeneration; Kpro, kerato-
prosthesis; LAD, left anterior descending; QALY, quality-adjusted life
year; TKR, total knee replacement
Type II Boston keratoprosthesis
JD Ament et al
Conflict of interest
Dr Dohlman receives no personal profits from the sale of
the Boston Keratoprosthesis. Proceeds go to the
Massachusetts Eye and Ear Infirmary, and are used
to support research and development. The authors
are/were employees of the Massachusetts Eye and Ear
Infirmary, and receive no financial benefit from the
publication of this data. Dr Ament is a Clinical Research
Fellow who is paid directly from Dr Dohlman’s research
and development fund.
We thank Kathy Colby, MD, PhDFMassachusetts Eye
and Ear Infirmary and Ann BurkeFCost and Budget
Manager. Both contributed to cost data.
Author contributions
Design of the study (JA, TS, SP, SS, JC, and CD); conduct
of the study (JA, TS, SP, SS, JC, and CD); analysis and
interpretation (JA, GP, JC, and TS); writing the article
(JA and TS); critical revision (JA, TS, SP, SS, GP, JC, and
CD); final approval (JA, TS, SP, SS, GP, JC, and CD);
data collection (JA, TS, SP, SS, and GP); provision of
materials (SP, SS, GP, JC, and CD); statistical expertise
(JA and JC); and literature search (JA and TS).
The study was found to be exempted from review by the
Human Studies Committee under Paragraph no. 4 of the
Code of Federal Regulations 45 CFR 46.101(b). An IRB
approval was received to collect data from medical records
of patient. The project does not fall under HIPAA require-
ments because no protected health information is recorded
or linked by code to data. The manuscript, its design, and
implementation are in full adherence to the Declaration of
Helsinki and all federal or state laws in the USA.
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What was known before
K It was unclear whether type II Boston Kpro was a cost-
effective medical intervention. Type I had recently been
shown to be highly cost effective; however, the patient
population requiring type II is drastically different. These
patients have severe autoimmune corneal disease and are
exceedingly debilitated.
What this study adds
K This study does two things: (1) it confirms that
type II Boston Kpro is cost effective (based on the
o100 000 $/QALY convention and similar modalities);
and (2) provides a cost-utility model from which
adaptations, improvements, and refinements can be
computed. It provides a foundation for which clinicians
and insurers can speak about utility, value, and cost.
Type II Boston keratoprosthesis
JD Ament et al
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Type II Boston keratoprosthesis
JD Ament et al
  • [Show abstract] [Hide abstract] ABSTRACT: Corneal transplantation or keratoplasty has developed rapidly in the past 10 years. Penetrating keratoplasty, a procedure consisting of full-thickness replacement of the cornea, has been the dominant procedure for more than half a century, and successfully caters to most causes of corneal blindness. The adoption by specialist surgeons of newer forms of lamellar transplantation surgery, which selectively replace only diseased layers of the cornea, has been a fundamental change in recent years. Deep anterior lamellar keratoplasty is replacing penetrating keratoplasty for disorders affecting the corneal stromal layers, while eliminating the risk of endothelial rejection. Endothelial keratoplasty, which selectively replaces the corneal endothelium in patients with endothelial disease, has resulted in more rapid and predictable visual outcomes. Other emerging therapies are ocular surface reconstruction and artificial cornea (keratoprosthesis) surgery, which have become more widely available because of rapid advances in these techniques. Collectively, these advances have resulted in improved outcomes, and have expanded the number of cases of corneal blindness, which can now be treated successfully. Femtosecond-laser-assisted surgery, bioengineered corneas, and medical treatment for endothelial disease are also likely to play a part in the future.
    Full-text · Article · May 2012
  • [Show abstract] [Hide abstract] ABSTRACT: To determine the long-term cost-effectiveness of osteo-odonto keratoprosthesis (OOKP) relative to no treatment among patients with end-stage corneal and ocular surface diseases in Singapore. Cost-effectiveness analysis based on data from a retrospective cohort study. From a health system perspective, we calculated the incremental cost-effectiveness ratio of OOKP treatment relative to no treatment over a 30-year horizon, based on data from a cohort of 23 patients who underwent OOKP surgery between 2004 and 2009 at Singapore National Eye Centre. Preoperative and postoperative vision-related quality-of-life values were estimated from patients' visual outcomes and were used to calculate the gain in quality-adjusted life years (QALYs) resulting from OOKP treatment. Unsubsidized costs for surgery, consultations, examinations, medications, follow-up visits, and treatments for complications were retrieved from patients' bills to estimate the total costs associated with OOKP treatment. Sensitivity analyses were conducted to test the robustness of the model. Over a 30-year period, OOKP treatment, compared with no treatment, improved QALYs by 3.991 among patients with end-stage corneal and ocular surface diseases at an additional cost of S$67 840 (US$55 150), resulting in an incremental cost-effectiveness ratio of S$17 000/QALY (US$13 820/QALY). Based on commonly cited cost-effectiveness benchmarks, the OOKP is a cost-effective treatment for patients with end-stage corneal and ocular surface diseases.
    Full-text · Article · Sep 2013
  • [Show abstract] [Hide abstract] ABSTRACT: Purpose: To report the visual outcomes of prosthetic replacement of the ocular surface ecosystem (PROSE) treatment in patients with ocular surface disease related to Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Design: Retrospective cohort study. Subjects: We included 86 patients (167 eyes) with history of SJS/TEN who underwent PROSE treatment from January 1, 2006, to January 1, 2011. Methods: Etiology, previous interventions, change in visual acuity, change in visual function, and duration of follow-up are reported. Paired t test and Friedman test with Dunn's post hoc test for multiple comparisons were used for statistical analysis. Main outcome measures: Visual acuity at last follow-up and visual function based on the National Eye Institute 25-item Visual Functioning Questionnaire (NEI VFQ-25) at 6 months. Results: We treated 35 males and 51 females with a history of SJS/TENS; median age was 36 years. The most common reported etiologies for SJS/TENS were antibiotics (n = 25), ibuprofen (n = 15), and lamotrigine (n = 11). The median visual acuity at the initial visit was 20/60 (range, 20/400-20/25; 0.48 logarithm of the minimum angle of resolution [logMAR]), and the visual acuity at completion of customization was 20/25 (range, 20/200-20/20; 0.096 logMAR; P < 0.001), with no decline in median acuity at the end of follow-up. Median duration of follow-up was 16 months. There was a significant improvement in the visual function of the patients based on the NEI VFQ-25 questionnaire (mean of 48 points at baseline vs. mean of 72 points at 6 months; P < 0.001). In addition, there was also an improvement in the self-reported general health of the patients (mean of 57 points at baseline vs. mean of 65 points at 6 months; P < 0.01). Conclusions: In a large cohort of patients with chronic ocular surface disease related to SJS/TEN, PROSE treatment offers sustained and significant large improvement in visual function and acuity.
    Article · Oct 2014
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