Corneal Opacity Management

ManagementCornea
Protocols
Management Protocols:
Corneal Opacity
Management
Kumari Reena Singh
MD
Kumari Reena Singh MD, Kavita Duraipandi MD, DNB, FICO
Dr. Rajendra Prasad Centre for Ophthalmic Sciences,
All India Institute of Medical Sciences, New Delhi
C
ornea is an optically clear and transparent structure.
Corneal disorders can results in deposition of additional
material (e.g., fluid, scar tissue, inflammatory debris,
metabolic) byproducts within one or multiple layers of the
cornea causing loss of corneal clarity. This loss in corneal
transparency is called as corneal opacity .Corneal diseases
represent the second leading cause of blindness in most
developing world countries. Nearly 80% of all corneal
blindness is avoidable.
Keratitis and trauma are the most frequent causes of corneal
blindness in developing countries. Important causes of
corneal opacity includes following:
Prevention and Early Detection
•
Neonatal corneal opacification caused by forceps
injury, herpes simplex keratitis, or bacterial keratitis
can be prevented.
•
Use of protective eyewear at work, in sports, and in
armed conflict can reduce trauma.
•
Early diagnosis and treatment of bacterial keratitis can
reduce scarring and opacification.
•
Appropriate treatment of the trichiasis, corneal
exposure, dry eye, neurotrophic cornea, and
autoimmune disease can reduce the incidence of
ulcerative keratitis associated with them.
Managements
Therapeutic strategy includes optical, medical, and surgical
alternatives.
Different aspects of managements
Rationale for treatment is only when corneal opacity is
associated with functional visual loss or discomfort. Less
commonly, cosmesis is an indication for treatment. Stromal
or endothelial dysfunction or disease may necessitate
intervention to stabilize the ocular surface to prevent further
complications. Few important things should be considered
before any planning for treatment, like;
1. Severety, site and depth of opacity:
Figure 1: Paracentral/peripheral (full
thickness or partial thickness) but involving
part of pupillary opening
a. Small central /paracentral/peripheral (full thickness
or partial thickness) but involving part of pupillary
opening (Figure 1).
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Corneal Opacity Management
Congenital
1.AxenfeldRieger
anomaly
2.Peter’s
anomaly
3.Sclerocornea
4.Dermoid
5.Leukoma
Nutritional
Vitamin A
deficiency
(xerophthalmia)
Metabolic
1.Mucopolysaccharidosis
2.Mucolipidoses
Lipidosis
3.Hypolipoproteinemias
4.Cystinosis
5.Fabry disease
Degenerations
1.Calcific
band
keratopathy
2.Crocodile
shagreen
Spheroidal
degeneration
3.Salzmann
nodular
degeneration
Pterygium
Dystrophies
Epithelial,
stromal and
endothelial
Inflammatory
and
immunologic
1.Infection
(bacterial,
fungal,
parasitic, and
viral)
2.Interstitial
keratitis
(nonsterile
and sterile)
3.Mooren’s
ulcer
4.Steven’s
Johnson
Syndrome
Neoplastic
1.Conjunctival/
corneal
intraepithelial
neoplasia
2.Melanosis/
melanoma
Trauma
1.Corneal
abrasion
predisposing
to microbial
keratitis
2.Penetrating
trauma
3.Chemical
injury
Doctor caused
(iatrogenic)
1.Pseudophakic
bullous
keratopathy
2.Inadvertent
exposure of the
cornea to topical
chlorhexidine
3.Drugs
(Tamoxifen,
Phenothiazines,
Antimalarials)
4.TASS(Toxic
anterior shock
syndrome)
Classifications
ICD 9 CM
ICD 10 CM
Minor corneal opacity
371.01
H17.81
Peripheral corneal opacity
371.02
H17.82
Central corneal opacity
371.03
H17.1
Adherent leukoma
371.04
H17.0
Phthisical cornea.
017.3, 371.05*
A18.59, H44.52
CM = Clinical Modification used in the United States; (–) = 1, right eye; 2, left eye; 3, bilateral * Code first underlying tuberculosis (017.3).
Refraction with corrective glasses or contact lenses
(both assessed with dialated and undialated pupil
to consider for optical iridectomy), with or without
cosmetic corneal tattooing /cosmetic contact
lenses.
b. Small, peripheral opacity not involving part
of pupillary opening (full thickness or partial
thickness).
These opacities may still compromise vision by
inducing distortions of the corneal curvature.
Refraction over a rigid contact lens can be helpful
in assessing potential visual acuity and may in
itself improve visual acuity. Also corrective glasses
can be prescribed.
c. Larger size corneal opacity involving pupillary
opening ,no improvement in vision after dilation
•
If only nebular corneal opacity and visual
requirement is not much or any systemic
or local disorders not allowing for surgical
correction then refraction for fitting glasses
and contact lenses , otherwise laser assisted
54 l DOS Times - Vol. 20, No. 9 March, 2015
corrections PTK, lamellar surgical corrections
(manual, microkeratome, femtolaser assisted)
(Figure 2a,b,c).
•
If deeper corneal involvement then depending
on depth of involvement LK, DALK (manual,
microkeratome, femtolaser assisted) .Rotation
autograft is another option.
•
If full thickness corneal involvement/adherent
leukomatous opacity is there and eye bank
facility is present then pkp could be options
(Figure 3).
2. Associated other vision decreasing problems
Like cataract, astigmatism, posterior segment disorders etc.
should be evaluated first then appropriate treatment should
be planned.
3. End stage disorders without visual potentials
Like in phthisical cornea or end stage glaucoma patients
with opacity, should be treated for pain and discomfort also
for cosmesis like corneal tattooing, contact lenses, artificial
eyes etc.
Management Protocols
(a)
(b)
(c)
Figure 2(a),(b),(c): Larger size corneal opacity involving pupillary opening, no
improvement in vision after dilation
Vision impairment may be reduced or eliminated by
spectacle or contact lens correction. Contact lenses are
good option for treatment of corneal scaring1. Corneal
tattooing/cosmetic contact lens can be an option for
rehabilitation, especially in patients where there was no
option of functional improvement by other treatments2.
Surgical Treatment
Selection of the surgical procedure is determined by the
depth and location of the opacity. The proposed surgery
should have an acceptable risk/benefit ratio with the
potential to reduce the patient’s disability significantly.
Procedures that may improve vision include the following:
•
Optical iridectomy: where cornea overlying the
potential iridectomy site is clear and there is a high risk
of complications for PK, e.g., Peter’s anomaly.
•
Chemical treatment/EDTA chelation: used for removal
of calcific band keratopathy.
•
Limbal stem cell graft: may be useful to restore the
corneal epithelium. An amniotic membrane graft
may be considered as a supportive substrate for the
epithelium.
•
Lamellar procedure: (Involves selective removal and
replacement of diseased corneal layers)
Figure 3: Full thickness corneal involvement/adherent
leukomatous opacity
Treatment
Depending on the etiology of the opacity, severity, needs
and health status of patient, treatment may be optical,
medical, surgical, or a combination.
Optical and Medical Treatment
Treatment of conditions like epithelial corneal edema,
poor ocular surface, high IOP or intraocular inflammation,
helps to improve visual and overall function also alleviate
discomfort or pain (Figure 4a,b). Treatment may be
necessary for underlying systemic disorders such as
immunocompromised status or connective tissue disease.
1.
Lamellar keratectomy: may improve corneal
clarity and smoothness in cases of anterior stromal
scarring associated with normal endothelial
function.
a.
Mechanical superficial keratectomy: works
best for opacities overlying Bowman’s
layer and superficial degenerations such as
epithelial membrane dystrophy and Salzmann
nodular degeneration.
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Corneal Opacity Management
(a)
(b)
Figure 4(a),(b): Corneal edema, poor ocular surface and intraocular inflammation
2.
Lamellar keratoplasty: useful in anterior to midstromal opacities in which endothelial function is
normal.
a.
Superficial Anterior Lamellar Keratoplasty
(SALK): Particularly when treating deeper
lesions which can not be treated by PTK.
This procedure can be Automated or Hemiautomated (HALK, cutting host bed with
microkeratome) suture assisted or sutures less
with glue.
b. Anterior Lamellar Keratoplasty (ALK): Manual,
Automated (microkeratome assisted) donor
graft can be sutured into the recipient bed or
suture assisted with glue.
c. Sutureless Femtosecond Laser - Assisted
Anterior Lamellar Keratoplasty (FALK)
Depth of the recipient corneal pathology is measured using
anterior segment OCT (AS-OCT). A femtosecond laser is
used to create the lamellar cut in the recipient with donor
corneas. Donor cut is adjusted according to the depth of
the lesions with an additional 10-20% thickness adjusted to
compensate for donor tissue swelling. After putting donor
lenticule the incision is dried, and flap adhesion is checked.
A bandage soft contact lens is placed over the cornea.
d. Deep Anterior Lamellar Keratoplasty (DALK)
(Figure 5a,b).
It removes and replaces total or near-total corneal stroma
while preserving host endothelium. The advantages
of DALK include reducing the risk of endothelial graft
56 l DOS Times - Vol. 20, No. 9 March, 2015
rejection, efficient visual rehabilitation relative to PK, and
also fewer complications including expulsive hemorrhage,
anterior synechia, postoperative endophthalmitis, and
glaucoma in comparison to PK. This procedure also
requires less rigid criteria for donor corneal tissue selection
that is often weighted toward donor endothelium in PK.
There are different methods of dissections of host cornea
like ; direct Open Dissection (Anwar in 1972), closed
Dissection (Melles Technique, 1999), dissection with
Hydrodelamination (Sugita and Kondo), dissection with Big
Bubble Technique, (Anwar’s 2002), Big Bubble technique
Combined with Femtosecond Laser Trephination. (SuwanApichon et al. 2006 and Price Jr. et al. 2009).
e. Posterior Lamellar Keratoplasty or Endothelial
Keratoplasty (EK)
Attempting to replace endothelial pathology, the first (PLK)
procedure was described by Barraquer in 1950. Melles
et al. offered sutureless PLK in 1998, using an air bubble
for graft fixation. In 2001, Terry and Ousley introduced
endothelial keratoplasty (EK) and deep lamellar endothelial
keratoplasty (DLEK). Later in 2005 Price Jr. and Price
performed Descemet stripping endothelial keratoplasty
(DSEK). A year later, Gorovoy added automation using
a microkeratome for Descemet stripping automated
endothelial keratoplasty (DSAEK). Subsequently, Descemet
membrane endothelial keratoplasty (DMEK) was described
by Melles et al. allowing transplantation of an isolated
endothelium-Descemet membrane layer (EDM) without
adherent corneal stroma. Later on Price et al. described
Descemet membrane automated endothelial keratoplasty
(DMAEK). Endothelial keratoplasty has lesser risk of
Management Protocols
(a)
(b)
Figure 5(a),(b): Deep Anterior Lamellar Keratoplasty (DALK)
endothelial graft rejection, early visual rehabilitation
relative to PK and also fewer complications. Two most
common early complications following DSAEK surgery
are graft dislocation (1 to 82%) and primary graft failure
(0-29%).
•
Rotation Autograft:
Rotational autograft can be an effective alternative to
standard penetrating keratoplasty for some patients
with corneal scars. Area of clear cornea is placed in the
geometric center of the cornea and the opacity is rotated
toward the limbus. The objective is to achieve the largest
possible optically clear zone. Mathematical variables
are set to maximize postoperative visual acuity and for
generalization of the geometric model3.
•
Penetrating keratoplasty:
Penetrating keratoplasty should be performed when
nonsurgical measures or less invasive procedures not
provide satisfactory visual outcome. Long term follow-up
care and patient cooperation are required to ensure success.
Patients remain at risk for allograft rejection throughout
life. There are various complications following Penetrating
keratoplasty including Intraoperative and Postoperative
complications.
•
Triple procedure:
It involves cataract surgery and intraocular lens implantation
along with lamellar, DSEAK and PKP procedure. Mostly
open sky cataract surgery done in PKP with cataract surgery
in case of PKP planned with closed chamber cataract
surgery to increase visibility, Lamellar corneal dissection
for visualization of the anterior chamber before triple
procedure can be done4.
•
Keratoprosthesis:
Used for severe corneal bilateral opacity where other
surgical options are not viable.
•
Conjunctival flap:
Surgical procedures to reduce the pain of corneal edema
(bullous and microcystic) in patients who are not candidates
for corneal transplantation.
So each case of corneal opacity should be evaluated
properly then managed. After visual rehabilitation,
postoperative care as well as treatment of complications
and recurrent disease is also important.
References
1. Grünauer Kloevekorn C , Habermann A, Wilhelm F et.al.; Contact
lens fitting as a possibility for visual rehabilitation in patients after
open globe injuries; [Article in German] Klin Monbl Augenheilkd.
2004;8):652-7.
2. S Pitz, R Jahn, L Frisch, A Duis, N Pfeiffer et. al.; Corneal tattooing: an
alternative treatment for disfiguring corneal scars optimal Size and
Location for Corneal Rotational Autografts A Simplified Mathematical
Model; British Journal of Ophthalmology, 2002;86:397-99
3. Natalie A. Afshari,Scott M. Duncan, Tasha Y et. al.; Optimal
Size and Location for Corneal Rotational Autografts A Simplified
Mathematical Mode. Arch Ophthalmol. 2006;3:410-13.
4. N Ardjomand, P Fellner, M Moray, C Wohlfart,et.al.; Lamellar
corneal dissection for visualization of the anterior chamber before
triple procedure; Eye 2007;21:1151–54.
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