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Boston Keratoprosthesis (KPro)

Synthetic cornea for end-stage corneal disease unsuitable for keratoplasty

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Göz Hastalıkları department. Book Appointment →

What is Boston Keratoprosthesis (KPro)?

The Boston keratoprosthesis (KPro) was developed by Dr. Claes Dohlman and is the most widely implanted synthetic cornea worldwide. The device consists of a clear polymethyl methacrylate (PMMA) front plate, a donor corneal carrier (allograft) with central trephination, and a titanium or PMMA back plate with holes for nutrition; the assembly is sutured to the host cornea like a keratoplasty.

Two designs exist: KPro Type 1 for patients with adequate tear production and lid function (most patients), and KPro Type 2 for severe end-stage ocular surface disease with cicatricial conditions and minimal tears, which requires permanent tarsorrhaphy with the device protruding through the lid. Type 1 has dramatically improved survival rates with vapor-deposited titanium back plates and rigid bandage contact lenses replacing prior PMMA designs.

Indications include multiple penetrating keratoplasty failures (gold standard indication), severe limbal stem cell deficiency without donor tissue, severe chemical or thermal burns, ocular cicatricial pemphigoid, Stevens-Johnson syndrome (Type 2), and aniridic keratopathy. Visual outcomes are excellent with 60-80% achieving 20/200 or better. Long-term complications include retroprosthetic membrane (most common), glaucoma (often progressive), endophthalmitis, sterile keratolysis, and device extrusion. Lifelong topical antibiotics, glaucoma surveillance, and bandage contact lens use are essential.

Symptoms

Severe vision loss from end-stage corneal disease
Multiple prior failed penetrating keratoplasties
Limbal stem cell deficiency unresponsive to autologous or allogeneic stem cell transplantation
Severe ocular surface disease (cicatricial pemphigoid, Stevens-Johnson syndrome, chemical burns)
Aniridic keratopathy
Severe corneal scarring
Bilateral corneal blindness
Failure of conventional medical and surgical therapy
Vascularized cornea precluding standard keratoplasty
Severe dry eye with corneal failure
Pediatric corneal blindness in selected cases
Posttraumatic corneal blindness
Inability to wear scleral lenses or other interventions
Patient willing and able to comply with intensive postoperative care
Light perception or hand motion vision threshold
Aphakia or pseudophakia (preferred status)

Risk Factors

Multiple failed penetrating keratoplasties (highest risk substrate)
Severe ocular surface disease
Stevens-Johnson syndrome and toxic epidermal necrolysis
Ocular cicatricial pemphigoid
Chemical and thermal burns
Aniridic keratopathy
Severe limbal stem cell deficiency
Mucous membrane pemphigoid
Atopic and vernal keratoconjunctivitis
Diabetes mellitus (impaired healing)
Smoking
Active inflammation
Severe glaucoma (relative contraindication)
Active uveitis
Inability to comply with intensive postoperative care
Limited social support for follow-up
Severe dry eye (especially for Type 1 candidates)
Mental illness affecting compliance
Pediatric age (challenging postoperative care)
Prior ocular trauma with extensive damage

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Multiple penetrating keratoplasty failures
  • Severe limbal stem cell deficiency unresponsive to stem cell transplant
  • Severe Stevens-Johnson syndrome with corneal blindness
  • Ocular cicatricial pemphigoid with corneal failure
  • Severe chemical or thermal burn with corneal blindness
  • Aniridic keratopathy
  • Bilateral corneal blindness
  • Vascularized scarred cornea
  • Inability to undergo or maintain conventional keratoplasty
  • Failed scleral lens or other surface management
  • Quality-of-life impairment from corneal blindness
  • Light perception or hand motion vision
  • Patient willing for intensive postoperative care

Treatment Methods

01
Comprehensive evaluation by cornea specialist with KPro experience
02
Preoperative assessment of retinal function (B-scan ultrasound, electroretinography, visual evoked potentials)
03
Glaucoma evaluation and optimization (essential due to high postoperative glaucoma rate)
04
Lid and tear assessment
05
Treatment of underlying systemic disease (immunosuppression for cicatricial pemphigoid)
06
Patient counseling on risks, benefits, and lifelong care requirements
07
Boston KPro Type 1 for adequate tear function (most patients)
08
Boston KPro Type 2 for severe ocular surface disease with minimal tears (with tarsorrhaphy)
09
Surgical technique with concurrent cataract extraction and intraocular lens placement (or aphakic implantation)
10
Glaucoma drainage device placement at time of KPro or staged
11
Trephination of donor cornea around KPro front plate
12
Suturing of carrier cornea to host with multiple sutures
13
Bandage contact lens placement immediately and worn lifelong
14
Topical antibiotic prophylaxis lifelong (vancomycin and a fourth-generation fluoroquinolone)
15
Topical corticosteroids long-term
16
Topical antiglaucoma medications as needed
17
Frequent postoperative visits (weekly initially, then monthly, then every 2-3 months lifelong)
18
Retroprosthetic membrane management with YAG laser membranotomy
19
Intensive glaucoma surveillance and treatment (Baerveldt or Ahmed valve, cyclophotocoagulation)
20
Endophthalmitis prophylaxis and rapid treatment if suspected
21
Sterile keratolysis monitoring (preventive corneal cross-linking adjacent to device, autologous serum, gas-permeable contact lens)
22
Device replacement for melt, extrusion, or persistent inflammation
23
Multidisciplinary care including cornea, glaucoma, retina, immunology
24
Long-term follow-up for life

Which Department to Visit?

You can visit our Göz Hastalıkları department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.