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Management of Vitreoretinal Complications in Eyes With Permanent Keratoprosthesis
Subhransu Ray, MD, PhD;
Bilal F. Khan, MD;
Claes H. Dohlman, MD, PhD;
Donald J. D'Amico, MD
Arch Ophthalmol. 2002;120:559-566.
ABSTRACT
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Objectives To evaluate the spectrum and treatment of posterior segment complications
in eyes that had undergone successful keratoprosthesis (KPro) placement and
to determine whether transeyelid vitrectomy techniques could be effectively
used in eyes otherwise vulnerable to surface exposure.
Design In the last 10 years, 110 patients received a Dohlman-Doane KPro at
the Massachusetts Eye and Ear Infirmary, Boston. We evaluated 22 eyes in 18
patients that required subsequent vitreoretinal surgery to treat posterior
segment complications. One surgeon using modified vitreoretinal techniques,
as described below, performed all vitreoretinal procedures.
Results The posterior segment complications included 6 cases of retro-KPro membranes,
13 cases of retinal detachments, and 5 cases of isolated vitreous opacity.
All 6 retro-KPro membranes were effectively removed by vitrectomy without
significant complication and 3 of these patients enjoyed improvement of visual
acuity of at least 5 Snellen lines. Of 13 cases of retinal detachment, 6 patients
had some improvement in visual acuity, 5 showed no appreciable change, and
2 had some decline in the final visual acuity. In all 5 cases of isolated
vitreous opacity, the media was effectively cleared with pars plana vitrectomy.
Three patients enjoyed improvement of visual acuity of at least 3 Snellen
lines. Four cases of transeyelid vitrectomy were attempted and anatomical
success was achieved in all 4 and vision improved in 3 of these patients.
No special surgical complications were encountered in any of the 22 eyes as
a result of these modified surgical techniques.
Main Outcome Measures Best preoperative and postoperative visual acuity and anatomical success
were evaluated in relation to the preoperative posterior segment complication.
Conclusions Modified vitreoretinal surgical techniques can be effectively and safely
used to treat posterior segment complications in patients with KPro devices.
Retro-KPro membranes and other vitreous opacities were the most amenable to
treatment. Retinal complications posed a special challenge. However, all of
these cases highlight that modified vitrectomy techniques can be used in eyes
with permanent KPro devices. These techniques can be performed without additional
risk to the eye. Additionally, we demonstrated that transeyelid vitrectomy
techniques could be used effectively to manage complications in eyes with
severe ocular surface disease without undue exposure of vulnerable tissues.
INTRODUCTION
ATTEMPTS TO rehabilitate clinically phthisical eyes and corneas that
are refractory to standard keratoplasty have been challenging. Since the first
description of an artificial prosthesis in 1789,1
numerous materials and methods have been used to functionally recreate the
anatomy of the cornea. These efforts are summarized in previous publications.2-3 These devices suffered from early postoperative
failure because of implant extrusion and uncontrollable inflammation. However,
with advancements in material design, surgical techniques, and postoperative
management, new models of keratoprostheses (KPros) can provide long-term solutions
for both the phthisical eye and end-stage corneal disease.4-6
This progress has shifted the focus to late-developing sequelae involving
the posterior segment. Posterior segment abnormalities in association with
a KPro may be present prior to KPro placement (as a consequence of injury,
previous ocular disease, or complication of prior surgical intervention),
may develop intraoperatively during KPro placement, or may occur postoperatively.
Management of such challenging vitreoretinal issues requires modified microsurgical
techniques to preserve vision in these revitalized eyes. In this article we
summarize our experience with patients who underwent KPro surgery and who
have required surgical intervention for posterior segment complications.
PATIENTS AND METHODS
To date, 146 cases of KPro surgery were performed at the Massachusetts
Eye and Ear Infirmary, Boston, with 110 cases performed in the last 10 years
using modified Dohlman-Doane KPro designs. These cases included 13 patients
with Stevens-Johnson syndrome, 27 with ocular cicatricial pemphigoid, 28 cases
of alkali burns, and 42 other cases that include trauma, viral keratitis,
and various corneal dystrophies.
All of the implanted KPro devices are of the original or modifications
of the Dohlman-Doane design.7 Preoperative
criteria and surgical placement of the KPro were previously described.8-9 The structural dimensions of type I
and type II KPro devices are shown in Figure
1.
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Figure 1. A Dohlman-Doane keratoprosthesis
type I (right) device is used in patients with adequate tear film stability.
The front plate has a 7-mm diameter with a central 3.5-mm, optically clear
zone. The back plate is 7 mm in base diameter. A Dohlman-Doane keratoprosthesis
type II (left) device is used in a patient with severe ocular surface disease.
The front plate has a 7-mm diameter and 3.5-mm, optically clear zone along
with a 2-mm anterior nub that protrudes through eyelid tissues. The back plate
measures 8.5 mm in base diameter.
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To identify the most common posterior segment complications, we retrospectively
reviewed the medical records of all of the patients who underwent KPro surgery
in the last 10 years who required pars plana vitreoretinal surgery. We analyzed
all of the 22 eyes in the 18 patients who required vitreoretinal surgery.
These included 12 patients with type I KPro devices and 6 with type II KPro
devices. The pre-KPro diagnoses in these patients included 3 patients having
ocular cicatricial pemphigoid, 2 having Stevens-Johnson syndrome, 3 having
chronic uveitis, 4 having chemical burns, and 1 each having atopy, trauma,
Fuchs dystrophy, graft-vs-host disease, pseudophakic bullous keratopathy,
and idiopathic corneal neovascularization. The posterior segment complications
included 6 cases of retro-KPro membranes, 13 cases of retinal detachment,
and 5 cases of isolated vitreous opacity. The exact preoperative diagnoses
are listed in Table 1. One of
us (D.J.D.) performed all of the surgical procedures required in these patients.
Informed consent, as determined by institutional requirements and regulations,
was obtained from all patients prior to surgery.
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Cases With Media Opacities*
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PREOPERATIVE EVALUATION
Preoperative evaluation typically required ultrasound evaluation, although
in rare cases indirect ophthalmoscopy was sufficient to characterize the posterior
segment abnormality. Doppler ultrasound of the optic nerve head for verification
of integrity of the central retinal vessels was performed in patients with
questionable light perception or suggestive of irreversible retinal damage.
In the specific case of retro-KPro membranes, referral for pars plana vitrectomy
(PPV) was made after either failure of the Nd:YAG capsulotomy to achieve the
desired outcome or when it was determined that such laser treatment could
induce further complications, as in the case of thick fibrovascular membranes.
In cases of suspected endophthalmitis, initial treatment attempts were made
with intravenous antibiotics following vitreous tap and injection. If these
treatments failed to achieve vitreous clearing, they were referred for PPV
with culturing of a vitreous sample.
Cases with vitreous hemorrhage were referred to the vitreoretinal service
when an underlying retinal tear or detachment was suggested. Initial studies
included B-scan ultrasonography when direct visualization was impaired. In
most cases of retinal detachment, direct visualization of the retina identified
the detachment. However, B-scan ultrasonography was used to identify the extent
of the detachment, sites of possible tears, as well as points of vitreous
adhesions. In most cases of retinal pathology, direct intraoperative visualization
provided the most accurate and useful characterization.
SURGICAL TECHNIQUES
Because the anterior segment anatomy is frequently foreshortened in
eyes undergoing KPro surgery, often with profound fibrosis and contracture
in the area of the iris root and ciliary body, incisions for vitrectomy were
located as anteriorly as possible in these cases. To place the incisions just
beyond the KPro back plate, 9-mm marks spanning the KPro center were placed
as entry sites for 3-port or 2-port PPV. Entry sites were made through the
conjunctiva with a microvitreoretinal blade. Infusion was established using
a variety of techniques. Although conventional sutured cannulas were used,
it was more common to use a bent 21-gauge butterfly needle with the tubing
taped to the eyelid to maintain position. This later technique had the advantage
of maintaining a formed globe from the beginning of the surgery. Bottle height
was maximized to maintain the chamber and facilitate intraocular hemostasis.
Zeigler and bent microvitreoretinal blades were alternatively used to incise
and free the retro-KPro membranes from the back plate, and the fragments were
removed with the vitrector. Once adequate visualization is achieved, the remainder
of the vitreous is removed as necessary. Patient 2 demonstrates a case of
simultaneous retro-KPro membrane and endophthalmitis (Figure 2).
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Figure 2. Case 2. Endophthalmitis and retro-keratoprosthesis
(KPro) membrane. A, Preoperative view of patient 2 demonstrating mild conjunctival
chemosis, retro-KPro membrane, and anterior vitreous debris. B, Intraoperative
view demonstrating secured infusion cannula inferiorly and bent microvitreoretinal
blade behind the KPro device stripping the retro-KPro membrane. C, Vitrector
in the anterior vitreous indicating some of the extensive vitreous veils that
were seen throughout the vitreous in this patient. D, Intraoperative view
showing numerous preretinal clumps of white blood cells and debris. After
a complete vitrectomy was performed, these were removed using a flute needle
and performing aspiration with the vitrector.
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Three-port vitrectomy was used in all cases of suspected retinal pathology
to allow for maximal visualization and flexibility in tissue manipulation.
A Charles irrigating contact lens was initially used for visualization of
the anterior vitreous. Further manipulations were performed using a contact
wide-field viewing system with a 130° wide-angle lens to maximize peripheral
visualization. When necessary, endolaser photocoagulation was performed with
a straight-probe. A 5000-centistoke silicone oil was used at the end of the
case for prolonged retinal tamponade in most cases, but long-acting gases
were also used. The eye was filled to the edge of the KPro back plate.
Many patients who a KPro device have severe ocular surface disease necessitating
the placement of a transeyelid type II KPro device. To avoid disturbing this
interface, a microvitreoretinal blade was used to simultaneously penetrate
full thickness through the eyelid, conjunctiva, and sclera into the vitreous
space. Infusion was established with a 21-gauge butterfly-needle technique.
The remainder of the techniques are similar to those described earlier for
the transconjunctival approach. The ports were closed with deep 10-0 nylon
skin sutures without the need for scleral sutures. Such a procedure was required
in case 3 in which a dense retro-KPro membrane limited visual acuity and was
refractory to Nd:YAG treatment. Figure 3
shows the surgical techniques used in the treatment of this patient.
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Figure 3. Case 3. Retro-keratoprosthesis
(KPro) membrane in a type II keratoprosthesis. A, Preoperative view demonstrating
a type II KPro device with a thick retro-KPro membrane. B, Calipers are set
on 9 mm to avoid hitting the KPro back plate. View shows microvitreoretinal
blade entering the vitreous space with one single passage through eyelid skin,
underlying ocular surface, and sclera. Skin hemostasis is achieved with a
20-gauge needle cautery to avoid inadvertent spillover into the vitreous space.
C, Two-port vitrectomy using butterfly-infusion needle superiorly and vitrector
inferiorly. The third instrument seen in the bottom-left corner is a 0.12-forceps
to stabilize the eye. After the leathery membrane was initially incised using
an microvitreoretinal blade, the fragments are gently removed with the cutting
action of a vitrector. Care is taken to avoid extensive traction on the membrane
as it may be firmly adherent to ciliary body or even peripheral retina. D,
After the membrane was removed a clear view of the anterior vitreous is possible.
The tip of the butterfly-infusion needle is visible. On postoperative day
1 the patient had 20/20 visual acuity.
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RESULTS
Of the 110 cases of KPro placement in the last 10 years at the Massachusetts
Eye and Ear Infirmary, there were a total of 22 cases in 18 patients with
posterior segment complications. The most common posterior segment problems
encountered were retro-KPro membranes, endophthalmitis, retinal detachments,
epiretinal membranes, and vitreous hemorrhages. The most common posterior
segment complication requiring surgical intervention was retinal detachment,
which was found either in isolation or in combination with a vitreous opacity
in 13 cases. The retinal detachments were seen in association with other retinal
pathology including extensive cyclitic membanes, epiretinal membranes, proliferative
vitreoretinopathy, subretinal fibrosis, and other preretinal vitreous adhesions.
There were 6 cases of retro-KPro membrane, 3 of which were in isolation. Two
of the remaining 3 were seen in association with a retinal detachment, and
the last was in the setting of concurrent endophthalmitis. Additionally, there
were 5 cases of isolated vitreous opacity related to endophthalmitis in 4
cases and chronic uveitis in 1 case.
SURGICAL OUTCOMES
All 6 retro-KPro membranes were effectively removed by vitrectomy without
significant hemorrhage and with complete clearing of the visual axis. The
3 patients with isolated retro-KPro membrane (cases 1, 3, and 4) enjoyed improvement
of visual acuity of at least 5 lines of Snellen. The 1 patient associated
with endophthalmitis (case 2) saw an improvement from light perception to
20/200. The 2 remaining patients (cases 20 and 22) were in the setting of
a concurrent retinal detachment and saw minimal to no improvement in vision,
although the membrane was effectively cleared from the optical axis.
Of the 13 cases of retinal detachment, 6 patients had some improvement
in visual acuity (cases 9, 11, 15, 18, 19, and 20), 5 showed no appreciable
change (cases 10, 12, 14, 21, and 22), and 2 had some decline in final visual
acuity (cases 16 and 17). Anatomical success could not be achieved in 4 patients
despite aggressive surgical intervention. Of the 6 patients who showed some
visual improvement, 4 had some other vitreous opacity that was simultaneously
cleared at the time of detachment repair; 2 with vitreous hemorrhage (cases
11 and 15) and 1 each with uveitis (case 18) and retro-KPro membrane (case
20). Of the remaining 7 patients who saw either no improvement or a decline
in vision, 3 patients demonstrated extensive proliferative vitreoretinopathy
(cases 16, 17, and 21). In all but 4 patients (cases 14, 19, 20, and 21),
the retina was successfully anatomically reattached postoperatively. The 4
patients who were determined to be inoperable were secondary to proliferative
vitreoretinopathy and chronic scarring.
In all 5 cases of isolated vitreous opacity (cases 5 through 8 and 13),
the media was effectively cleared with a PPV approach. Three of these patients
enjoyed improvement of visual acuity of at least 3 Snellen lines (cases 5
through 7). One patient (case 8) had a chronic wound leak around the KPro
stem that progressed to device extrusion. One patient with chronic uveitis
(case 13) developed a retinal detachment postoperatively.
Four cases of transeyelid vitrectomy were performed (cases 3, 18, 19,
and 22). In all 4 cases anatomical success was achieved and vision improved
in 3 of these patients (cases 3, 18, and 19), with patient 3 enjoying dramatic
improvement from hand motions to 20/20 visual acuity after removal of a thick
fibrovascular retro-KPro membrane. No surgical complications were seen in
any of these patients that could be associated with the transeyelid approach.
In summary, in all 22 cases of vitreoretinal surgery performed for posterior
segment complications in KPro eyes, no special surgical complications were
induced by these modified techniques. No cases of uncontrolled vitreous hemorrhage,
retinal detachment, giant retinal tears, choroidal detachment, endophthalmitis,
or KPro device damage were noted in any of the aforementioned cases.
COMMENT
The increase in long-term stability of KPro devices resulted in a shift
in the types of complications encountered. There have been 173 cumulative
postoperative years with vision of 20/200 or better starting from preoperative
visions of counting fingers or worse over the period 1990 through 2000. The
factors that have improved surgical outcome include glaucoma shunts, changes
in KPro design, prophylactic antibiotics, and immunomodulators. Traditional
complications such as corneal melt, implant extrusion, and glaucoma still
figure prominently. However, the most common causes for failure are encountered
in the posterior segment. Leading among these is uncontrollable uveitis as
well as other causes of posterior segment pathology such as retro-KPro membrane,
endophthalmitis, and retinal detachment. Management of these complications
requires modified vitreoretinal techniques.
RETRO-KPro MEMBRANES
Approximately 30% of eyes will eventually develop retro-KPro membranes.
Most are amenable to Nd:YAG laser treat ment. However, thick and fibrovascular
membranes are more safely managed by surgical excision. These membranes may
be extensive and can span pars plana to pars plana. Forceful manipulation
of such membranes may result in giant retinal tears and detachments. Attention
is directed at minimizing inflammation and hemorrhage, as these are effective
stimulants for membrane recurrence. To this end, a core vitrectomy may be
simultaneously performed.
Histopathological analysis of one such removed membrane (Figure 4) revealed dense, relatively avascular fibrous tissue with
numerous fibroblasts, some of which are pigmented. A dense acellular zone
of collagen, with an occasional foreign body giant cell surrounds this tissue.
This most likely represents corneal downgrowth around the stem of the KPro.
A similar pathology is often seen in failed cases of corneal grafts or cyclitic
membranes. The visual improvement seen postoperatively in patients initially
seen with isolated retro-KPro membranes highlights the relative efficacy and
safety of PPV in eyes with KPro devices with minimal risk to the eye.
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Figure 4. Pathological sample of a retro-keratoprosthesis
membrane demonstrating a dense acellular collagen layer (seen at the top of
the photograph) lying over a thicker relatively avascular fibrous layer with
numerous fibroblasts (hematoxylin-eosin, original magnification x200).
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ENDOPHTHALMITIS
As with any intraocular surgery, one of the most debilitating complications
is endophthalmitis.10 In KPro surgery the rate
of sterile endophthalmitis is higher than in other intraocular procedures.
This may be secondary to immune reaction to antigens released during tissue
melt and necrosis. The clinical picture of sterile and infectious endophthalmitis
can be varying and confounding, but in general, sterile endophthalmitis is
more insidious in onset and occurs in the absence of substantial ocular pain
or injection. Vitreous taps, as well as intravitreal and intravenous antibiotics
are administered in cases suggestive of endophthalmitis. The initial antibiotics
of choice are vancomycin hydrochloride and ceftazidime, though these are tailored
once the culture results become available. The most common organisms are endogenous
flora and include Streptococcus species, Staphylococcus species, Proprionibacterium acnes,
Candida species, Cryptococcus species, and Moraxella species. Surgical vitrectomy in infectious cases
can be performed for vitreous biopsy, debulking of organism load, and removal
of vitreous scaffolding on which the organisms may proliferate. Vitrectomy
in these cases may also theoretically reduce the risks of subsequent vitreoretinal
fibrosis and adhesions as well as their subsequent complications.
RETINAL DETACHMENTS
Treatment of retinal detachment in KPro-treated eyes is challenging
both in visualization as well as surgical access to involved retinal tissues.
Retinal detachments may be secondary to retinal breaks, but may also be due
to vitreoretinal adhesions and proliferative vitreoretinopathy that accompany
chronic inflammation. In such cases, removal of the instigating traction is
paramount to successful results. Another visually significant finding in chronic
inflammation is epiretinal membrane formation, as demonstrated in patient
17. While basic surgical principles are obeyed in KPro-treated eyes, the surgical
approaches must be modified to achieve good visual outcome. Scleral buckling
procedures are often of limited value owing to the compromised scleral and
anterior segment tissues seen in these disease states. One of the great limitations
lies in the lack of a suitable expansile substance to achieve adequate retinal
tamponade. Although we are able to achieve anatomical success in many of these
cases, and in many cases stabilize the vision, the prognosis for visual restoration
remains poor. Perhaps earlier intervention or prophylactic treatment in high-risk
cases may increase the success rate.
GENERAL PRINCIPLES
Despite the exact nature of the surgical procedure, several common obstacles
emerge in KPro-treated eyes. These include obtaining adequate surgical exposure,
visualization, and hemostasis. Though exposure and visualization are limited
in a closed eye system, we prefer this to the intraoperative complications
encountered in open-sky techniques. During PPV, a wide-angle lens system may
be used with the illumination of a light pipe to obtain more posterior and
peripheral views. Two-port vitrectomy is often adequate in simple cases of
vitreous washout, membrane peel, or obtaining a biopsy specimen. However,
in more complicated scenarios, standard 3-port vitrectomy is required. During
instrument manipulation, care must be taken to avoid damage to the back plate,
as iatrogenic opacities in the visual axis will limit visual prognosis. Finally,
as blood in the vitreous is an active stimulant, special care must be paid
to limiting hemorrhage, both intraocular as well as spillover from external
ports. Beginning the surgery with an intraocular penetration by a 21-gauge
needle for irrigation limits hemorrhage, permits additional instrument introductions,
and prevents the transient inadvertent collapses seen with sutured cannula
techniques. The maintenance of a closed, firm eye throughout the procedure
is perhaps the single most important aspect in achieving successful visual
outcomes in these eyes. We advocate a limited vitreous washout at procedure
completion if significant red blood cells are present. Postoperative management
includes topical antibiotics, 1% of atropine sulfate, and steroids which may
be administered periocularly.
Special interest is given to patient 3, who, to our knowledge, is the
first case of transeyelid PPV. To preserve the stability of type II KPro devices,
it was crucial to obtain surgical access without disrupting the protective
surface barriers. Vitrectomy in type II KPro devices poses a unique challenge
in all 3 categories of exposure, visualization, and hemostasis. Full-thickness
vitrectomy requires a modified infusion device, for which we used a 1.5-in,
21-gauge, butterfly-infusion needle that we inserted as the very first maneuver.
This was followed by transeyelid penetration with a microvitreoretinal blade
for additional instrument access across the eyelids. With experience, it became
relatively straightforward to reintroduce various instruments across these
transeyelid incisions into the eye. It is possible that the use of cannulated
vitrectomy incisions would be beneficial in these cases to facilitate navigating
the instruments across the eyelid and sclera.
CONCLUSIONS
The previous cases demonstrate that modified surgical techniques may
be successfully used to treat visually devastating complications in KPro-treated
eyes. Though general vitreoretinal surgical principles are obeyed, special
attention is paid to exposure, visualization, and hemostasis. Keratoprosthesis
surgery is itself an evolving field, and management of posterior segment complications
will similarly require continual modification. There are several limitations,
which still await technological and surgical advancements. The vision rescued
by heroic anterior segment surgery in end-stage ocular disease can be preserved
by continued diligence and innovation in the management of associated vitreoretinal
complications.
AUTHOR INFORMATION
Submitted for publication September 18, 2001; final revision received
December 10, 2001; accepted December 21, 2001.
This study was supported in part by the Vitreoretinal Research Fund,
Boston (Dr D'Amico).
Corresponding author and reprints: Donald J. D'Amico, MD, Massachusetts
Eye and Ear Infirmary, 243 Charles St, Boston, MA 02114 (e-mail: djdamico{at}meei.harvard.edu).
From the Retina (Drs Ray and D'Amico) and Cornea (Drs Khan and Dohlman)
Services, Massachusetts Eye and Ear Infirmary, and the Department of Ophthalmology,
Harvard Medical School, Boston. The authors have no commercial, proprietary,
or financial interest in the devices, products, or companies described in
this article.
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