Indications for penetrating keratoplasty in the Philippines
Ma. Dominga B. Padilla, MD Marie Antonette T. Eltanal-Pascual, MD
CORNEAL transplantation has become one of the most
successful procedures in organ transplantation in the past
six decades. Though this success is attributable to the
relative immune privilege naturally inherent to the cornea
and to advances in surgical techniques and instrumentation, it is also largely the establishment of reliable eye
banks around the world that resulted in increased
availability and better quality of donor corneal tissues.
In areas of the world with established eye banks where
penetrating keratoplasty (PKP) has become a routine
procedure, the indications for PKP and the changing
trends of those indications have been well studied.
the Philippines, however, this information is lacking.
Prior to the founding of the Eye Bank Foundation of
the Philippines and the subsequent opening of its eye
bank, the Santa Lucia International Eye Bank of Manila
(SLIEB), PKP had been performed sporadically using
eyeballs harvested from cadavers and stored in make-do
moist chambers and the corneal buttons occasionally
donated from abroad. Since its establishment, the SLEBIF
has become the major source of transplantable corneal
tissues for medical institutions and private clinics in the
Philippines, with PKP becoming a routine procedure. This
study determined the leading indications for PKP in the
Philippines using records of the SLIEBF and compared
these indications with those of other countries.
Each donor corneal button distributed to a surgeon or
medical institution by the SLIEBF was accompanied with
a request for the following information: (1) surgeon/institution performing the PKP; (2) general recipient information, such as age and sex, medical and ophthalmic
history; and (3) type of procedure performed (i.e. whether
combined with cataract extraction, etc). This postoperative
report became part of the SLIEBF database.
Postoperative reports returned to the SLIEB from
January 1, 1996 to December 31, 2004 were reviewed. The
indications for PKP were tabulated annually and cumulatively over a nine-year period. The same nomenclature
was used to facilitate comparison with other published
Categories of indications listed were the following:
pseudophakic bullous keratopathy (PBK), aphakic bullous
keratopathy (ABK), Fuch’s dystrophy, corneal dystrophies,
keratoconus, corneal scar, microbial keratitis, viral
infection, noninfectious keratitis, trauma, regraft, Steven
Johnson Syndrome, congenital defect, and glaucoma.
Corneal scar included those due to unspecified causes,
whether from previous inflammation or infection or old
ocular trauma. Regraft, whether due to graft rejection or
failure, was given priority over all other diagnoses regardless of the primary indication for PKP. Intraocular lens
implants (IOLs) included both anterior- (AC) and
posterior-chamber (PC) lenses. Microbial keratitis
included both active and old microbial cases. Viral
infection included herpes simplex keratitis and measlesassociated infections. Causes of trauma were chemical,
mechanical, or thermal injuries. Corneal dystrophies
included dystrophies other than Fuch’s dystrophy.
Miscellaneous causes were listed under “others”. Those
without any indication were listed under “unspecified”.
Demographic data of the recipient included age, sex,
and socioeconomic status (i.e. charity when the patient
was operated in a training institution with reduced fees
versus pay when the patient paid the regular processing
fees). For each indication for PKP, the differences in
gender and socioeconomic conditions were analyzed using
Chi-square test. A p value less than 0.05 was considered
SLIEBF processed a total of 6,225 corneal tissues from
January 1996 to December 2004. Of these, 1,265 could
not be used due to positive serologic testing, mostly for
active hepatitis B (971 or 76.8% of serologically unfit
tissues). A total of 4,074 corneal tissues were used for
optical PKP, of which 2,874 (70.5%) were distributed to
109 institutions and ophthalmologists in the Philippines
and 1,200 (29.5%) to 24 other countries. The remaining
corneas were set aside for tectonic use, research, or were
found unsuitable for surgery due to coexisting medical
Of the 2,874 corneas distributed locally, 2,131
postoperative reports were obtained (retrieval rate of
74.1%) and reviewed for inclusion into the study.
The age of the recipients requiring PKP ranged from
2 months to 96 years old, with a mean of 47. 2 years. A
bimodal distribution with peaks at age groups 35 to 45
and 65 to 75 years was seen (Figure 1). 59.5% of the
recipients were males and 53.8% belonged to the lower
The main indications for PKP were corneal scar, PBK,
microbial keratitis, regraft, and ABK (Table 1). These top
5 indications accounted for 76.6% of cases.
Yearly tabulation of the top 5 indications for PKP
showed PBK peaking from 1996 to 1998 and going down
thereafter. There was an increasing trend for regraft since
the middle of 2001, and a decreasing trend for corneal
scar (Figure 2).
As indications for PKP, corneal scar, microbial keratitis,
and trauma were 74%, 60%, and 33% respectively more
common in males than females (Table 2). PBK, Fuch’s
dystrophy, corneal stromal dystrophy, and glaucoma
causing bullous keratopathy were more frequent among
females. In particular, Fuch’s, stromal dystrophy, and
glaucoma as indications for PKP were 2 times more likely
to be seen in females (Table 2).
Corneal scar, microbial keratitis, and viral infection
were the more frequent indications among the lower
socioeconomic (charity) group, while PBK, ABK, regraft,
Fuch’s, glaucoma, and keratoconus were the more
common indications among the higher socioeconomic
group (Table 2). Among pay patients, the conditions cited
were almost 2 times more common, with the exception of
keratoconus which was 3.5 times.
The leading indications for PKP in the developed world
are PBK, regraft, and keratoconus,
in contrast to developing countries like India, Taiwan, Israel, and China
where the most common indications are corneal scar and
microbial keratitis. The results of this study were very
similar to those of studies in the developing world, with
an overall rate of greater than 20% and 10% for corneal
scar and microbial keratitis respectively (Table 3).
Corneal scar and microbial keratitis together made up
40.5% of all indications for PKP in this study. From 1971
to 1991, the most common condition treated at the Cornea
and External Disease Section of the Department of
Ophthalmology, University of the Philippines-Philippine
General Hospital was microbial keratitis.
Most of the
infectious corneal ulcers ended up in significant scarring
of the cornea. Both conditions were also more common
among patients of lower socioeconomic status (Table 2),
similar to the results found in India.
This may reflect the
fact that poor patients have less resources for proper
medical treatment and limited access to immediate care,
especially in the rural areas. Conversely, microbial keratitis
and corneal scar were less common among wealthy
patients who were more likely to seek immediate care
before the condition worsened and caused significant
visual impairment. Approximately 50% of the infectious
keratitis in this study were fungal in etiology which was
associated with vegetable-matter injury,
commonly seen among poor farmers in the Philippines.
Figure 2 shows that the incidence of corneal scar peaked
during the years 1996 to 1998 with a gradual decrease
thereafter. The high numbers of PKP done for corneal
scar in the early years of the eye bank may be a reflection
of the backlog of these cases prior to the establishment of
the eye bank, and which decreased once corneas became
PBK was the second leading indication for PKP in this
study at 19.7%, with peaks from 1996 to 1997 reflecting a
backlog and stabilization thereafter (Figure 2). Other
studies also showed incidences greater than 10%,
except for the UK study where its relatively low percentage
of 7.6% was attributed to a more conservative approach
and slower acceptance of intraocular lenses
period of the study.
The age distribution in this study was bimodal, with
peaks at two age groups; the first at 35 to 45 years due to
corneal scars and microbial keratitis, and the second at
65 to 75 years due to PBK (Figure 1). This distribution fits
the age group (20 to 50 years) when microbial keratitis is
and the elderly group when PBK and
cataract are higher. This bimodal distribution was also seen
in other studies.
The rate of regraft (9.8%) in this series was considerably
lower than those reported in developed countries where
incidences approached 20% or more (Table 3). From 2001
onwards, however, there was a steady increase, a reflection
of the increasing number of PKPs performed over time
and the potential for graft failure,
a trend similar to those
of other studies.
10, 17, 18
Fuch’s dystrophy was more common among females in
this study, consistent with well-known epidemiological data
In developed countries, keratoconus is one of the
leading indications for PKP, unlike in developing countries
in Asia including the Philippines where the incidence is
much lower (Table 3). The reason for this difference is
not clear. Mamalis et al.
suggested that there may be a
higher incidence of keratoconus among Caucasians,
particularly those from Northern Europe or Scandinavia.
PBK, ABK, regraft, Fuch’s dystrophy, and keratoconus
as indications for PKP were more common among those
belonging to the higher socioeconomic status. This can
be attributed to the fact that poorer patients treated at
training institutions were more likely to delay surgery due
to financial constraints and likely to tolerate the blurry
vision longer. Wealthier patients have greater access to
expert care and were more likely to have the conditions
Trauma as a cause for PKP is much more common
among males, as reported in both foreign and local
15, 20, 21
Males have been shown to be at higher risk
for traumatic eye injury in occupational and recreational
and are associated with higher incidences of
microbial keratitis and corneal scar. Valenton found that
trauma was the predisposing factor in 75% of bacterial
and fungal keratitis and that manual laborers, farmers,
and construction workers were particularly vulnerable. In
our study, microbial keratitis and corneal scar were seen
more frequently among poorer patients while trauma was
not associated with socioeconomic status. Possible
explanations include the type of surgery done—most of
the poorer patients may have opted for cheaper surgical
treatments such as primary repair or tectonic grafts instead
Viral infections were also more common among the
charity patients undergoing PKP. Though timely medical
treatment with topical and oral antiviral medications may
provide cure, patients with fewer funds and less access to
expert care may have poorer control of the disease process
leading to significant corneal scarring.
The top 5 indications for PKP in this study have
relatively poorer prognosis due to the associated neovascularization and active inflammation commonly present
that are well-known risk factors for graft failure.
in contrast to keratoconus as a leading indication in
developed countries with better prognosis. Regraft as an
indication for PKP is, therefore, likely to increase.
In summary, corneal scar was the most frequent
indication for PKP in the Philippines from 1996 to 2004,
followed by PBK and microbial keratitis. Those belonging
to the lower socioeconomic sector were more likely to have
corneal scar, microbial and viral infection while wealthier
patients were more likely to have keratoconus, PBK, ABK,
and Fuch’s dystrophy. Regraft as an indication for PKP
has also increased since 2001.
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The authors gratefully acknowledge the statistical assistance of Dr. Marie Carmela
Lapitan of the Department of Urology, Philippine General Hospital.