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4 Incidence/Comparison of PK Versus DSEK Versus DMEK: Outcomes for Rejection

4 Incidence/Comparison of PK Versus DSEK Versus DMEK: Outcomes for Rejection

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Graft Rejection in Endothelial Keratoplasty


Fig. 11.7 (a, b) A DMEK graft carrying only Descemet’s membrane and endothelium (Courtesy,

Dr. Soosan Jacob, Dr. Agarwal’s Eye Hospital, Chennai, India)

to replace only the posterior host corneal layers with a partial-thickness donor cornea [56]. Deep lamellar endothelial keratoplasty (DLEK) was a modification of this

technique [57]. Both techniques necessitated manual lamellar dissections, which

were technically challenging. Melles et al. [58], Price and Price [59], and Price and

Price [60] were among the first to report a further evolution in the procedure, from

lamellar dissection to stripping of Descemet’s membrane and endothelium.

Descemet’s stripping endothelial keratoplasty and Descemet’s stripping automated

endothelial keratoplasty (both referred in this chapter as DSEK). An even newer

procedure, Descemet’s membrane endothelial keratoplasty (DMEK), combines the

descemetorhexis stripping with an even thinner donor graft without stroma

(Fig. 11.7). The Pre-Descemet’s endothelial keratoplasty (PDEK) graft transplants

a pre-Descemet’s layer, Descemet’s membrane, and endothelium.

While much of the drive to transition from penetrating keratoplasty to the various

iterations of endothelial keratoplasty was for surgical safety, as well as faster and

improved visual rehabilitation, there has been great interest in possible differences

in rejection rates between the two groups. While the cornea enjoys immune privilege, it is not absolute.



While there has been research comparing PK versus DSEK/DLEK rejection rates,

there is not complete consensus in the published literature. Most of the studies that

have examined this clinical question involve different eyes from different patients.

One of the few studies that examine PK vs. DSEK in the same patient is from

Kosker et al., who published a retrospective analysis examining 30 eyes of 15

Fuchs’ patients at Wills Eye Institute who underwent PK in one eye and DSEK in

the other eye for corneal edema [62]. In the first postoperative year, two DSEK eyes

had graft rejection episodes as compared to four PK eyes. All the cases responded to

topical steroids. This study was unique in comparing the two surgeries in the same

patient, but was limited by its small sample size and retrospective review.


C. Shieh and A.N. Carlson

Overall, it seems that the majority of retrospective comparative studies have

noted lower DSEK/DLEK rejection rates, as compared to PK. In contrast, the data

from prospective studies and registries suggests that the PK and DSEK/DLEK

rejection rates are more equivalent. The ability to draw conclusions from these studies is limited, at times, by the lack of a standardized post-operative steroid regimen

for prophylaxis/rejection. As it is not possible to cover all of the published studies,

we will first discuss the two major meta-analysis that have been performed, then

subsequently describe some of the key studies in the literature.



In an overview of the literature, a 2011 Cochrane review [66] examined the data for

DSEK/ DLEK vs. PK and found that while the rates of endothelial rejection were

lower following DSEK/ DLEK, overall the evidence was limited, and was based on

one nonrandomized comparative case series from Allan et al [63] and several cohort

studies. Cohort studies of PK reported an incidence of graft rejection between 5.3

and 23.2 % (median 6.7%, mean 7.4%) with a median follow-up of 24 months (mean

25.5%) [66]. Three EK cohort studies reported an incidence of graft rejection of 1.2–4

%, with no significant difference in rejection rate as compared to PK, but the mean

follow-up duration in all EK studies (mean 6 months) was noticeably shorter than in

the PKP group (mean 16.6 months) [63, 66, 67, 68].

A 2009 meta-analysis by the American Academy of Ophthalmology of DSEK

safety and outcomes alone (not in comparison to PK), found that the literature reflects

a mean endothelial graft rejection rates of 10% (range of 0 to 45 %) and a mean primary

graft failure rate of 5% (range of 0–29 %) [71]. The endothelial rejection data was

gathered from 16 out of the available 34 studies. The follow-up ranged from 3 to 24

months. Most rejection episodes were successfully treated with topical or oral steroids.

The authors raise the possibility that these numbers may actually be an under-representation of rejection rates, given the relatively short and incomplete patient follow-up.


Prospective studies

Cheng et al, published in 2009 on the rejection rates of femtosecond laser-assisted

endothelial keratoplasty (FLEK) versus penetrating keratoplasty (PK) in patients

with corneal endothelial disease [130]. This was a multicenter trial of 80 eyes of 80

patients, and was conducted at five ophthalmic centers in the Netherlands as part

of the Dutch Lamellar Corneal Transplantation Study. At 12 months, the authors

found that only one eye (2.8%) in the FLEK group, and one eye (2.5%) in the

PK group had an episode of rejection. The study’s strength is that it is one of the

only prospective randomized studies comparing EK to PK. As the study, however,

examined femtosecond-laser assisted EK rather than the standard microkeratomeassisted preparation of EK, the results may not directly correlate with standard EK.

Additionally, there was not a standardized steroid protocol for both groups in the


Graft Rejection in Endothelial Keratoplasty


trial, and whereas every patient in the PK group was still on topical steroids at the

end of the study, this was not true for the FLEK group (80.6% of the FLEK patients

were still on topical steroids).

Another prospective study by Bahar et al. in 2008 also examined 64 PK eyes and 64

DSEK/DLEK eyes at a single center [64]. This was a non-randomized study, and they

found that acute rejection was uncommon in all groups within 12 months of surgery:

(4.2 %) in the PK group, (4.4 %) in the DLEK group, (2.2 %) in the DSAEK group.


Multicenter, comparative studies

The Allan et al. multicenter comparative case series [63] mentioned in the Cochrane

review, examined two groups: 199 EK eyes (76% DLEK, 24% DSEK) as compared

to 708 PK eyes. In contrast to the PK eyes (which were drawn from the Swedish

Corneal Transplant Registry), the EK eyes were the sum total of a single-center

prospective cohort combined with a retrospective review of EK outcomes from 3

other centers. At an average follow-up of 24 months, the authors reported a significantly lower incidence of rejection episodes in EK (7.5%) as compared to PK

(13%), as well as fewer EK graft failure cases from rejection (6.7%) versus PK

(28.3%). The results were potentially confounded, though, by a few factors. First,

the two different groups had different steroid regimens: the EK patients had much a

much higher rate (80%) of continued use of topical steroid medication, as compared

to PK patients (almost all patients in the Swedish Corneal Transplant Registry had

topical steroids tapered off within 6 months of surgery). Additionally, patients with

any stromal neovascularization or inflammation were excluded from the EK group,

whereas it was not possible to exclude or isolate these patients in the PK group.

Many of the authors in the Allan et al paper [63] were involved in another 2010

paper by Price and associates [69], retrospectively comparing the 3-year post-operative outcomes of 173 EK eyes against the 410 PK eyes of the Cornea Donor Study

(CDS). The authors found similar results as Allan et al paper: while the EK and PK

graft success rate and endothelial cell loss rate were comparable, the DSEK patients

had a lower probability of a rejection episode (9%) compared to PK patients (20%),

and of the failures that were attributed to a rejection episode, there were more PK

failures (3.1%) versus DSEK (0.6%). Potential confounding variables were similar

to that of the Allan et al paper [63]. First, the EK and the PK groups had different

steroid regimens. Furthermore, similar to the Allan et al paper, the disease demographics between the two groups were not perfectly equivalent, such as a higher

percentage of Fuchs in the DSEK cohort (85%) vs. PK (64%) or a higher percentage

of bullous keratopathy in the PK cohort (32%) vs. DSEK (13%).



Interestingly, in contrast to the lower EK rejection rates of the other studies, a multicenter cohort study from the United Kingdom Transplant Registry (UKTR) of


C. Shieh and A.N. Carlson

3486 cornea transplants, reported no significant difference in 2 year rejection-free

survival between EK (DSEK/DLEK/possible DMEK) and PK in eyes with Fuchs

(93% PK vs. 94% EK) or Bullous Keratopathy (88% PK vs. 90% EK) [61]. The

authors noted that it was not possible to distinguish the type of EK, but noted that

few, if any DMEKs were performed in the period that was studied. Similar results

were found for those rejection episodes that led to graft failure in the 32 Fuchs eyes

(50% PK vs. 60% EK) and the 63 Bullous Keratopathy eyes (85% PKs vs. 76%

EKs). A limitation of this study is that post-operative steroid protocols were not

captured. Unlike some other studies on graft rejection, though, this study did not

exclude patients with signs of inflammation (injection, keratic precipiates, etc) at

the time of surgery. The authors reported that Fuchs patients with signs of inflammation at time of surgery were 3.5 times more likely to develop rejection as compared to those without signs of inflammation.

Uniquely, the Australian Corneal Graft Registry as an observational prospective

cohort study found that PKs enjoyed significantly better graft survival than endokeratoplasty (DSEK/DMEK) performed for Fuchs or bullous keratopathy

(p < .001). Notably, despite the higher PK survival rate reported, the data for the

failure attributed to irreversible rejection followed similar trends as that from other

studies: it was lower for DSEK/DMEK (12%), as compared to PK (30%). The

authors did find that experienced surgeons who had performed > 100 registered

endothelial keratoplasties, enjoyed significantly better graft survival than surgeons

who had performed fewer grafts (< 100 keratoplasties). Additionally, similar to the

United Kingdom Transplant Registry, the post-operative topical steroid regimen for

routine prophylaxis and for rejection was at the discretion of the ophthalmologist

and was not documented [131].


DSEK/DMEK After Failed PK

There are fewer studies investigating DSEK or DMEK as a second consecutive graft

following a prior failed PK. The largest study comes from the Australian Cornea

Graft Registry, where Keane et al. compared graft survival for 400 eyes, which had

either DSEK (65 PK-DSEK eyes) or repeat PK (335 PK-PK eyes) following a prior

(now failed) PK originally performed for keratoconus or bullous keratopathy. The

authors found that there were similar rates of graft failures due to irreversible immunological rejection between the PK-DSEK (7.7%) and PK-PK group (6.6%).

However, the authors found that the PK-PK group had significantly better graft

survival at a mean follow-up of 2 years, even when the indication for the second

graft was narrowed to those grafts that failed due to endothelial failure/rejection.

Surprisingly, in multivariate analysis, the occurrence of rejection in the first graft

did not influence survival of the second graft, nor was the diagnostic indication for

the first graft a risk factor for the second graft. Furthermore, oversizing or undersizing the EK graft in relation to the size of the prior failed PK had any impact on the


Graft Rejection in Endothelial Keratoplasty


Fig. 11.8 PDEK on failed penetrating keratoplasty graft: (a) Preop; (b) postoperative day 5 (C3F8

tamponade); (c) 3 weeks postop (BCVA 20/30); (d) 6 months postop (BCVA 20/30) (Courtesy, Dr.

Soosan Jacob, Dr. Agarwal’s Eye Hospital, Chennai, India)

survival. Lastly, in multivariate analysis, the authors found that the length of survival of the first PK (> 2 years) significantly influenced survival of the second graft

(PK or EK), despite the fact that EK was less likely to be performed for those eyes

which did not survive more than 2 years [132].

LV Prasad also evaluated the outcomes of repeat PK or DSEK under PK in 112

eyes that had a prior failed therapeutic keratoplasty for infectious keratitis. In a

retrospective study, they determined no statistically significant difference in rejection between the two groups at one year post-operatively [133]. Mitry et al, in a

retrospective multicenter study, examined the rejection rates DSEK after PK alone,

without comparing to a PK-PK group [70]. In contrast to the findings by Keane et

al, the authors discovered that any rejection episode prior to failure of the PK was a

significant predictor of post-DSEK rejection and failure. Out of 201 eyes with 6–22

month follow-up (mean 13-month follow-up), 16.7 % eyes had a post-DSEK rejection episode, and 7.3 % of these patients having a second rejection episode

(Fig. 11.8). Lastly, Gundlach et al. performed a retrospective analysis of 5 DMEKs

performed to treat graft failure after PK. While this group was not compared to

a PK-PK group, the small PK-DMEK group had no episode of rejections at 6

months [134].



C. Shieh and A.N. Carlson


In endothelial keratoplasty the donor endothelium is located in an immune-privileged location, as there are decreased numbers of donor dendritic cells as they are

located mainly in the superficial stroma. Dendritic cells are the most efficient of the

antigen-presenting cells, and are involved in host sensitization through the activation of T cells. Following this argument, others have proposed that in DMEK, the

absence of both donor epithelium and stroma, leads to diminished antigenic and

dendritic cell load with a corresponding lower risk of rejection [71].

A 2013 review by Maier et al. of the case series available in the literature noted

a <1-3% DMEK transplant rejection rate [72]. Later in 2014, the Melles group published on the largest group of DMEK eyes (500) and found only 7 rejection episodes

(< 1%) [55]. Also in 2014, the Price group examined pseudophakic patients who

had DMEK surgery alone (292 eyes) versus patients who had combined DMEK and

cataract surgery (200 eyes); there was no difference in rejection rate in either group

(0%) at the relatively short follow-up of 6 months [74].

DMEK rejection rates have also been compared to DSEK or PK. Initially in 2011,

the Price group performed a small comparative retrospective case series of 15 patients

who underwent DSEK in the first eye and DMEK in the fellow eye; there was no

statistically significant difference in rejection rates or endothelial cell loss at one year

[135]. Later, the Price group performed a larger study in which 141 prospectively followed DMEK patients were retrospectively compared to historical DSEK (598 eyes)

and PK groups (30 eyes) with similar patient population demographics using the same

steroid regimen and criteria to diagnose rejection in all three groups [65]. While the

different transplant groups had some dissimilarities in their indication for the EK (i.e.

bullous keratopathy made up 12% of the DSEK group versus 3% in the DMEK

group), the authors showed significantly decreased rates of rejection in DMEK (0.7

%), as compared to the historical control groups of DSEK (9 %) and PK (17 %) [65].

Lastly, Price and associates evaluated the outcomes of 55 secondary DMEK

recipients after failed primary DMEK, and also a paired fellow-eye analysis of a

subgroup of 29 patients who underwent secondary DMEK in 1 eye and successful

primary DMEK in the fellow eye. At a median follow-up of 18 months (range, 3-61

months), there were no rejection episodes in the repeat DMEK recipient eyes [136].


Risk Factors/Prevention

In organ transplantation, it is necessary to minimize antigenic difference between

host and donor. The cornea, however, has demonstrated surprising findings in studies on cornea allografts. The Collaborative Corneal Transplantation Studies (CCTS)

investigated the effect of donor–recipient histocompatibility matching and crossmatching on the survival of penetrating keratoplasty transplants in high-risk patients

[24]. In the CCTS, there was no benefit to histocompatibility matching, but the


Graft Rejection in Endothelial Keratoplasty


ABO-incompatible blood group had higher rates of failure from rejection as compared to the ABO-compatible group. This was in contrast to the Cornea Donor studies, which did not find a significant difference in rejection rates in groups that were

ABO incompatible or compatible [76]. Overall, in penetrating keratoplasty, tissue

matching in high-risk keratoplasty has been associated with a reduction of graft

rejection [42]. Several clinical studies indicate that HLA class I matching confers a

survival advantage in high-risk cases [77–80], although other authors did not support this observation [81–83]. The clinical data on the relevance of HLA-DR and

ABO blood group antigens in graft survival are even more ambiguous [79–87].

Corneal graft rejection most commonly occurs during the first year after surgery

[42]. Intraoperative and postoperative factors that have been proposed to decrease

risk of rejection are mostly applicable to PKs: intraoperative avoidance of decentration of recipient bed and good graft host apposition and postoperative timely

intervention with suture vascularization [52]. Eccentric grafts in PK are likely at

higher risk due to their proximity to the vascularized limbus (Figs. 11.9 and 11.10).

Similarly, the PK literature suggests that larger grafts are at increased risk of graft

rejection due to greater antigen load and the proximity of antigen-presenting cells

to the host limbal vasculature (Fig. 11.11) [88, 89]. The contradictory report of

smaller grafts presenting increased rejection risk may be due to a selection bias

toward surgeons preferentially using smaller grafts in high-risk eyes [24]. While

it has been hypothesized that endothelial grafts with larger diameters or eccentric

centration may increase the risk of rejection due to increased proximity to the host

uveal tissue and limbus, longer-term studies are needed to ascertain whether larger

endothelial donor size increases risk or rejection [64]. It has been proposed that the

sutures of PK patients, especially loose or broken sutures, provide an inflammatory

stimulus for neovascularization and therefore rejection [90]. It has been argued that

endothelial keratoplasty (DLEK, DSEK, DMEK), with its sutureless or early suture

Fig. 11.9 An eccentric

graft is closer to the

vascularized limbus and

therefore more susceptible

to rejection (Courtesy, Dr.

Soosan Jacob, Dr.

Agarwal’s Eye Hospital,

Chennai, India)


C. Shieh and A.N. Carlson

Fig. 11.10 A

nonvascularized cornea,

lack of inflammation and

peripheral anterior

synechiae/synechiae to

graft as well as avoiding a

graft reaching up to the

limbus along with the

judicious use of

immunosuppression in the

postoperative period all

help to decrease risk of

rejection (Courtesy, Dr.

Soosan Jacob, Dr.

Agarwal’s Eye Hospital,

Chennai, India)

Fig. 11.11 Large graft

size and peripheral


predispose to rejection

(Courtesy, Dr. Soosan

Jacob, Dr. Agarwal’s Eye

Hospital, Chennai, India)

removal, presents decreased risk of rejection. Silk should not be used due to its

pro-inflammatory effect. Instead, common materials include nylon and polypropylene, with some surgeons even moving to corneal glue or sealants to close the main


The major modifiable risk factor in endothelial keratoplasty is the post-operative

steroid regimen regardless of the type of surgery, the literature indicates that shorter

steroids treatment is associated with increased episodes of rejection. Overall, the

survival rate of grafts has improved with the use of topical steroids and systemic

immunosuppression [63]. Various immunosuppressive regimens are used, but most

surgeons treat low-risk cases with topical steroids four times a day initially with

tapering over a period of 4–6 months [42]. With medium- to high-risk corneal transplants, a more intensive regimen of steroids every 1–2 h initially with a slower taper


Graft Rejection in Endothelial Keratoplasty


over 6 months. Some surgeons taper off the steroids totally while others maintain

once daily indefinite use. The Price group’s prospective DMEK study of 400 eyes

over two years demonstrated decreased rejection rates in patients who continued

daily fluorometholone 0.1 % after the first year (0%) compared to those who discontinued use (6%) [137].

While long-term steroid use is protective against graft rejection, steroids carry

their own increased risk of steroid-response intraocular pressure elevation, progression of glaucoma, as well as development of cataracts or infectious keratitis. The

Price group further investigated whether the strength of the topical steroid affected

the rejection rates in DMEK patients: they prospectively compared topical prednisolone acetate 1 % vs. fluorometholone 0.1 % (FML) administration for post-operative months 2 through 12 in 325 DMEK eyes [91]. While the FML group had a

slightly higher rejection rate (1.4%) as compared to the prednisolone group (0%),

there was no statistically significant difference between the rejection rates of the

two study groups. In contrast, the prednisolone group had a significantly higher

proportion of patients who exceeded the defined intraocular pressure (IOP) elevation threshold (22%) as compared to the FML group (6%), as well as initiation/

increase of glaucoma medications (17% vs 5%). The authors note that the similar

endothelial cell densities and cell loss in both groups indicate that there is not subclinical immune-mediated endothelial cell damage occurring in the FML group.

The Price group later published similar results when comparing loteprednol 0.5%

gel versus prednisolone acetate 1% in DMEK eyes using an equivalent protocol

when substituting loteprednol gel for FML [150]. Interestingly, in a different retrospective examination of 598 DSEK eyes over 2 years, the Price group found that

patients with a prior history of glaucoma or steroid-responsive ocular hypertension

had 1.8 times the relative risk for initial rejection episode, as these patients were

more likely to have their steroid strength or dosing reduced due to elevated IOP

[92]. The authors suggest that these patients therefore should be examined more

frequently for signs of rejection. Additionally, in a separate paper, the Price group

noted that medically-managed glaucoma patients had significantly improved 5-year

graft survival and decreased endothelial rejection rates leading to graft failure versus those with surgically managed glaucoma (prior glaucoma shunt or trabeculectomy) [138]. While to our knowledge, there has not been a similar study done in a

large DSEK series, and it is not possible to say whether these DMEK results are also

generalizable to DSEK, this is relevant as in a large DSEK series it was found that

on topical prednisolone acetate 1 %, 34 % of the eyes developed increased intraocular pressure (24 mmHg) in the first year after transplantation. In the same study,

African Americans were found to have a five times higher risk of rejection compared with that of whites [92]. It has been proposed that this may be due to an

increased rate of inflammation after intraocular surgery associated with skin pigmentation or with an increased innate healing response, which also seems to influence success with filtration surgery.

It has been shown in a retrospective case control study over 5 years, that a prior

rejection episode in a DSEK patient is a risk factor for additional rejection episodes

[138]. Mitry et al. also found that prior episodes of rejection were a significant risk


C. Shieh and A.N. Carlson

factor for subsequent DSAEK failure in PK patients who had a subsequent DSEK

after failed PK [70]. This was independent of age or a history of a glaucoma shunt.

The study population of cornea graft recipients has also been examined for

demographic risk factors. African-American DSEK recipients have been found to

have significantly increased relative risk of experiencing a graft rejection episode as

compared with Caucasian patients [92], which corresponds to the CCTS findings

that African–American PK recipients have higher rates of immunological graft reaction. It has been proposed that this may be due to the correlation of increased skin

pigmentation with greater inflammation and healing after intraocular surgery, as

African-American race also seems to influence the success of glaucoma filtration

surgery [139]. Pediatric PK patients are especially vulnerable to rejection due to a

robust inflammatory response, with higher rates of irreversible graft rejection (45%

to 72%) [24, 140]. The heightened risk is weighed against the possibility of deprivation amblyopia in pediatric patients. Due to the technical challenges of pediatric

endothelial keratoplasty, the data is limited on rejection rates in this population. A

small case series of 19 pediatric eyes with varying conditions had lower rejection

rates (1 case of rejection, < 6% of eyes) than the published rejection rates in pediatric penetrating keratoplasty (22% to 43.4%) [140, 141]. Factors that do not significantly influence risk of DSEK rejection include: recipient age, recipient sex, and

whether the DSEK of the fellow eye was grafted within one year of the first eye [92].

Neither, also, does there appear to be a significant difference in DSEK rejection risk

between Fuchs patients versus bullous keratopathy patients [92]. There have been

case reports linking influenza vaccination with rejection in PK patients [100], and

while we do not advocate against vaccination administration, informed endothelial

keratoplasty patients may benefit from self-surveillance and augmenting the frequency of corticosteroid administration in the immediate period after vaccination.

Herpes Simplex Virus (HSV) keratitis also has been proposed as a minor cause

for failed endothelial keratoplasty. In a retrospective interventional case series, Yin

et al, examined failed DSEK grafts with immunohistochemical staining and qualitative real-time polymerase chain reaction (PCR) for HSV-1 DNA [104]. These tools

were also utilized on the donor corneoscleral rims in HSV-1 positive cases. HSV-1

DNA was isolated from 2 of 51 failed DSAEK grafts (4.0 %), and the corresponding

corneoscleral donor rims were negative for HSV-1, suggesting that recipient reactivation, rather than donor transmission, may play a role in HSV infection.



Corticosteroids are still the gold standard for treating graft rejection. The mechanism of corticosteroids is multifactorial. Not only do corticosteroids block prostaglandin synthesis by inhibiting phospholipase A2 and the lipo-oxygenase pathways,

they also decrease cytokine production and inhibit chemotaxis and phagocytosis of

cells [52]. Furthermore, they restore microvascular permeability and decrease cellular and fibrinous exudation [52] (Fig. 11.12).


Graft Rejection in Endothelial Keratoplasty


Fig. 11.12 Acute graft rejection in PDEK in a patient with ICE syndrome and anterior synechiae

who stopped topical steroids (a) and close-up view of cornea edema and haze (c). Rapid and complete recovery of corneal transparency and visual acuity to 20/20 was obtained with intensive steroid treatment (b) and close-up view of improved cornea clarity (d) (Courtesy, Dr. Soosan Jacob,

Dr. Agarwal’s Eye Hospital, Chennai, India)

There are a number of ways to administer steroids, whether topical or systemic.

For systemic administration, the physician needs to choose between oral steroids or

intravenous pulsed steroids.

Depending on the rejection severity, the patient should instill topical corticosteroids as frequently as every hour. The corticosteroid eye drops should not be tapered

until there is clinical improvement, and the patient should be followed closely.

Systemic oral or intravenous steroids may also be considered as an adjunct to topical steroid drops. Besides avoiding the potential side effects of osteoporosis and

diabetes with prolonged oral steroids, the mechanism of pulse therapy is thought to

stem from the inducement of lymphopenia and suppression of inflammation. While

there is not robust data on the benefits of systemic oral steroid administration with

hourly topical steroids versus hourly topical steroids alone, Hill et al. noted that in

those patients who presented within 8 days of the symptom onset of acute rejection, a single dose of intravenous methylprednisolone (500 mg) was associated with

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4 Incidence/Comparison of PK Versus DSEK Versus DMEK: Outcomes for Rejection

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